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
17 select MODULES_USE_ELF_REL
23 # Options that are inherently 64-bit kernel only:
24 select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
25 select ARCH_SUPPORTS_INT128
26 select ARCH_USE_CMPXCHG_LOCKREF
27 select HAVE_ARCH_SOFT_DIRTY
28 select MODULES_USE_ELF_RELA
29 select NEED_DMA_MAP_STATE
31 select X86_DEV_DMA_OPS
32 select ARCH_HAS_SYSCALL_WRAPPER
37 # ( Note that options that are marked 'if X86_64' could in principle be
38 # ported to 32-bit as well. )
43 # Note: keep this list sorted alphabetically
45 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
46 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
47 select ARCH_32BIT_OFF_T if X86_32
48 select ARCH_CLOCKSOURCE_DATA
49 select ARCH_CLOCKSOURCE_INIT
50 select ARCH_DISCARD_MEMBLOCK
51 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
52 select ARCH_HAS_DEBUG_VIRTUAL
53 select ARCH_HAS_DEVMEM_IS_ALLOWED
54 select ARCH_HAS_ELF_RANDOMIZE
55 select ARCH_HAS_FAST_MULTIPLIER
56 select ARCH_HAS_FILTER_PGPROT
57 select ARCH_HAS_FORTIFY_SOURCE
58 select ARCH_HAS_GCOV_PROFILE_ALL
59 select ARCH_HAS_KCOV if X86_64
60 select ARCH_HAS_MEMBARRIER_SYNC_CORE
61 select ARCH_HAS_PMEM_API if X86_64
62 select ARCH_HAS_PTE_SPECIAL
63 select ARCH_HAS_REFCOUNT
64 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
65 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
66 select ARCH_HAS_SET_MEMORY
67 select ARCH_HAS_STRICT_KERNEL_RWX
68 select ARCH_HAS_STRICT_MODULE_RWX
69 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
70 select ARCH_HAS_UBSAN_SANITIZE_ALL
71 select ARCH_HAS_ZONE_DEVICE if X86_64
72 select ARCH_HAVE_NMI_SAFE_CMPXCHG
73 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
74 select ARCH_MIGHT_HAVE_PC_PARPORT
75 select ARCH_MIGHT_HAVE_PC_SERIO
76 select ARCH_SUPPORTS_ACPI
77 select ARCH_SUPPORTS_ATOMIC_RMW
78 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
79 select ARCH_USE_BUILTIN_BSWAP
80 select ARCH_USE_QUEUED_RWLOCKS
81 select ARCH_USE_QUEUED_SPINLOCKS
82 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
83 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
84 select ARCH_WANTS_THP_SWAP if X86_64
85 select BUILDTIME_EXTABLE_SORT
87 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
88 select CLOCKSOURCE_WATCHDOG
89 select DCACHE_WORD_ACCESS
90 select EDAC_ATOMIC_SCRUB
92 select GENERIC_CLOCKEVENTS
93 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
94 select GENERIC_CLOCKEVENTS_MIN_ADJUST
95 select GENERIC_CMOS_UPDATE
96 select GENERIC_CPU_AUTOPROBE
97 select GENERIC_CPU_VULNERABILITIES
98 select GENERIC_EARLY_IOREMAP
99 select GENERIC_FIND_FIRST_BIT
101 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
102 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
103 select GENERIC_IRQ_MIGRATION if SMP
104 select GENERIC_IRQ_PROBE
105 select GENERIC_IRQ_RESERVATION_MODE
106 select GENERIC_IRQ_SHOW
107 select GENERIC_PENDING_IRQ if SMP
108 select GENERIC_SMP_IDLE_THREAD
109 select GENERIC_STRNCPY_FROM_USER
110 select GENERIC_STRNLEN_USER
111 select GENERIC_TIME_VSYSCALL
112 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
113 select HAVE_ACPI_APEI if ACPI
114 select HAVE_ACPI_APEI_NMI if ACPI
115 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
116 select HAVE_ARCH_AUDITSYSCALL
117 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
118 select HAVE_ARCH_JUMP_LABEL
119 select HAVE_ARCH_JUMP_LABEL_RELATIVE
120 select HAVE_ARCH_KASAN if X86_64
121 select HAVE_ARCH_KGDB
122 select HAVE_ARCH_MMAP_RND_BITS if MMU
123 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
124 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
125 select HAVE_ARCH_PREL32_RELOCATIONS
126 select HAVE_ARCH_SECCOMP_FILTER
127 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
128 select HAVE_ARCH_STACKLEAK
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
147 select HAVE_EXIT_THREAD
148 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
149 select HAVE_FTRACE_MCOUNT_RECORD
150 select HAVE_FUNCTION_GRAPH_TRACER
151 select HAVE_FUNCTION_TRACER
152 select HAVE_GCC_PLUGINS
153 select HAVE_HW_BREAKPOINT
155 select HAVE_IOREMAP_PROT
156 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
157 select HAVE_IRQ_TIME_ACCOUNTING
158 select HAVE_KERNEL_BZIP2
159 select HAVE_KERNEL_GZIP
160 select HAVE_KERNEL_LZ4
161 select HAVE_KERNEL_LZMA
162 select HAVE_KERNEL_LZO
163 select HAVE_KERNEL_XZ
165 select HAVE_KPROBES_ON_FTRACE
166 select HAVE_FUNCTION_ERROR_INJECTION
167 select HAVE_KRETPROBES
169 select HAVE_LIVEPATCH if X86_64
170 select HAVE_MEMBLOCK_NODE_MAP
171 select HAVE_MIXED_BREAKPOINTS_REGS
172 select HAVE_MOD_ARCH_SPECIFIC
176 select HAVE_OPTPROBES
177 select HAVE_PCSPKR_PLATFORM
178 select HAVE_PERF_EVENTS
179 select HAVE_PERF_EVENTS_NMI
180 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
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_FUNCTION_ARG_ACCESS_API
189 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
190 select HAVE_STACK_VALIDATION if X86_64
192 select HAVE_SYSCALL_TRACEPOINTS
193 select HAVE_UNSTABLE_SCHED_CLOCK
194 select HAVE_USER_RETURN_NOTIFIER
195 select HOTPLUG_SMT if SMP
196 select IRQ_FORCED_THREADING
197 select NEED_SG_DMA_LENGTH
198 select PCI_DOMAINS if PCI
199 select PCI_LOCKLESS_CONFIG if PCI
202 select RTC_MC146818_LIB
205 select SYSCTL_EXCEPTION_TRACE
206 select THREAD_INFO_IN_TASK
207 select USER_STACKTRACE_SUPPORT
209 select X86_FEATURE_NAMES if PROC_FS
211 config INSTRUCTION_DECODER
213 depends on KPROBES || PERF_EVENTS || UPROBES
217 default "elf32-i386" if X86_32
218 default "elf64-x86-64" if X86_64
220 config ARCH_DEFCONFIG
222 default "arch/x86/configs/i386_defconfig" if X86_32
223 default "arch/x86/configs/x86_64_defconfig" if X86_64
225 config LOCKDEP_SUPPORT
228 config STACKTRACE_SUPPORT
234 config ARCH_MMAP_RND_BITS_MIN
238 config ARCH_MMAP_RND_BITS_MAX
242 config ARCH_MMAP_RND_COMPAT_BITS_MIN
245 config ARCH_MMAP_RND_COMPAT_BITS_MAX
251 config GENERIC_ISA_DMA
253 depends on ISA_DMA_API
258 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
260 config GENERIC_BUG_RELATIVE_POINTERS
263 config GENERIC_HWEIGHT
266 config ARCH_MAY_HAVE_PC_FDC
268 depends on ISA_DMA_API
270 config RWSEM_XCHGADD_ALGORITHM
273 config GENERIC_CALIBRATE_DELAY
276 config ARCH_HAS_CPU_RELAX
279 config ARCH_HAS_CACHE_LINE_SIZE
282 config ARCH_HAS_FILTER_PGPROT
285 config HAVE_SETUP_PER_CPU_AREA
288 config NEED_PER_CPU_EMBED_FIRST_CHUNK
291 config NEED_PER_CPU_PAGE_FIRST_CHUNK
294 config ARCH_HIBERNATION_POSSIBLE
297 config ARCH_SUSPEND_POSSIBLE
300 config ARCH_WANT_HUGE_PMD_SHARE
303 config ARCH_WANT_GENERAL_HUGETLB
312 config ARCH_SUPPORTS_OPTIMIZED_INLINING
315 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
318 config KASAN_SHADOW_OFFSET
321 default 0xdffffc0000000000
323 config HAVE_INTEL_TXT
325 depends on INTEL_IOMMU && ACPI
329 depends on X86_32 && SMP
333 depends on X86_64 && SMP
335 config X86_32_LAZY_GS
337 depends on X86_32 && !STACKPROTECTOR
339 config ARCH_SUPPORTS_UPROBES
342 config FIX_EARLYCON_MEM
345 config DYNAMIC_PHYSICAL_MASK
348 config PGTABLE_LEVELS
350 default 5 if X86_5LEVEL
355 config CC_HAS_SANE_STACKPROTECTOR
357 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
358 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
360 We have to make sure stack protector is unconditionally disabled if
361 the compiler produces broken code.
363 menu "Processor type and features"
366 bool "DMA memory allocation support" if EXPERT
369 DMA memory allocation support allows devices with less than 32-bit
370 addressing to allocate within the first 16MB of address space.
371 Disable if no such devices will be used.
376 bool "Symmetric multi-processing support"
378 This enables support for systems with more than one CPU. If you have
379 a system with only one CPU, say N. If you have a system with more
382 If you say N here, the kernel will run on uni- and multiprocessor
383 machines, but will use only one CPU of a multiprocessor machine. If
384 you say Y here, the kernel will run on many, but not all,
385 uniprocessor machines. On a uniprocessor machine, the kernel
386 will run faster if you say N here.
388 Note that if you say Y here and choose architecture "586" or
389 "Pentium" under "Processor family", the kernel will not work on 486
390 architectures. Similarly, multiprocessor kernels for the "PPro"
391 architecture may not work on all Pentium based boards.
393 People using multiprocessor machines who say Y here should also say
394 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
395 Management" code will be disabled if you say Y here.
397 See also <file:Documentation/x86/i386/IO-APIC.txt>,
398 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
399 <http://www.tldp.org/docs.html#howto>.
401 If you don't know what to do here, say N.
403 config X86_FEATURE_NAMES
404 bool "Processor feature human-readable names" if EMBEDDED
407 This option compiles in a table of x86 feature bits and corresponding
408 names. This is required to support /proc/cpuinfo and a few kernel
409 messages. You can disable this to save space, at the expense of
410 making those few kernel messages show numeric feature bits instead.
415 bool "Support x2apic"
416 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
418 This enables x2apic support on CPUs that have this feature.
420 This allows 32-bit apic IDs (so it can support very large systems),
421 and accesses the local apic via MSRs not via mmio.
423 If you don't know what to do here, say N.
426 bool "Enable MPS table" if ACPI || SFI
428 depends on X86_LOCAL_APIC
430 For old smp systems that do not have proper acpi support. Newer systems
431 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
435 depends on X86_GOLDFISH
438 bool "Avoid speculative indirect branches in kernel"
440 select STACK_VALIDATION if HAVE_STACK_VALIDATION
442 Compile kernel with the retpoline compiler options to guard against
443 kernel-to-user data leaks by avoiding speculative indirect
444 branches. Requires a compiler with -mindirect-branch=thunk-extern
445 support for full protection. The kernel may run slower.
447 config X86_CPU_RESCTRL
448 bool "x86 CPU resource control support"
449 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
452 Enable x86 CPU resource control support.
454 Provide support for the allocation and monitoring of system resources
457 Intel calls this Intel Resource Director Technology
458 (Intel(R) RDT). More information about RDT can be found in the
459 Intel x86 Architecture Software Developer Manual.
461 AMD calls this AMD Platform Quality of Service (AMD QoS).
462 More information about AMD QoS can be found in the AMD64 Technology
463 Platform Quality of Service Extensions manual.
469 bool "Support for big SMP systems with more than 8 CPUs"
472 This option is needed for the systems that have more than 8 CPUs
474 config X86_EXTENDED_PLATFORM
475 bool "Support for extended (non-PC) x86 platforms"
478 If you disable this option then the kernel will only support
479 standard PC platforms. (which covers the vast majority of
482 If you enable this option then you'll be able to select support
483 for the following (non-PC) 32 bit x86 platforms:
484 Goldfish (Android emulator)
487 SGI 320/540 (Visual Workstation)
488 STA2X11-based (e.g. Northville)
489 Moorestown MID devices
491 If you have one of these systems, or if you want to build a
492 generic distribution kernel, say Y here - otherwise say N.
496 config X86_EXTENDED_PLATFORM
497 bool "Support for extended (non-PC) x86 platforms"
500 If you disable this option then the kernel will only support
501 standard PC platforms. (which covers the vast majority of
504 If you enable this option then you'll be able to select support
505 for the following (non-PC) 64 bit x86 platforms:
510 If you have one of these systems, or if you want to build a
511 generic distribution kernel, say Y here - otherwise say N.
513 # This is an alphabetically sorted list of 64 bit extended platforms
514 # Please maintain the alphabetic order if and when there are additions
516 bool "Numascale NumaChip"
518 depends on X86_EXTENDED_PLATFORM
521 depends on X86_X2APIC
522 depends on PCI_MMCONFIG
524 Adds support for Numascale NumaChip large-SMP systems. Needed to
525 enable more than ~168 cores.
526 If you don't have one of these, you should say N here.
530 select HYPERVISOR_GUEST
532 depends on X86_64 && PCI
533 depends on X86_EXTENDED_PLATFORM
536 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
537 supposed to run on these EM64T-based machines. Only choose this option
538 if you have one of these machines.
541 bool "SGI Ultraviolet"
543 depends on X86_EXTENDED_PLATFORM
546 depends on X86_X2APIC
549 This option is needed in order to support SGI Ultraviolet systems.
550 If you don't have one of these, you should say N here.
552 # Following is an alphabetically sorted list of 32 bit extended platforms
553 # Please maintain the alphabetic order if and when there are additions
556 bool "Goldfish (Virtual Platform)"
557 depends on X86_EXTENDED_PLATFORM
559 Enable support for the Goldfish virtual platform used primarily
560 for Android development. Unless you are building for the Android
561 Goldfish emulator say N here.
564 bool "CE4100 TV platform"
566 depends on PCI_GODIRECT
567 depends on X86_IO_APIC
569 depends on X86_EXTENDED_PLATFORM
570 select X86_REBOOTFIXUPS
572 select OF_EARLY_FLATTREE
574 Select for the Intel CE media processor (CE4100) SOC.
575 This option compiles in support for the CE4100 SOC for settop
576 boxes and media devices.
579 bool "Intel MID platform support"
580 depends on X86_EXTENDED_PLATFORM
581 depends on X86_PLATFORM_DEVICES
583 depends on X86_64 || (PCI_GOANY && X86_32)
584 depends on X86_IO_APIC
590 select MFD_INTEL_MSIC
592 Select to build a kernel capable of supporting Intel MID (Mobile
593 Internet Device) platform systems which do not have the PCI legacy
594 interfaces. If you are building for a PC class system say N here.
596 Intel MID platforms are based on an Intel processor and chipset which
597 consume less power than most of the x86 derivatives.
599 config X86_INTEL_QUARK
600 bool "Intel Quark platform support"
602 depends on X86_EXTENDED_PLATFORM
603 depends on X86_PLATFORM_DEVICES
607 depends on X86_IO_APIC
612 Select to include support for Quark X1000 SoC.
613 Say Y here if you have a Quark based system such as the Arduino
614 compatible Intel Galileo.
616 config X86_INTEL_LPSS
617 bool "Intel Low Power Subsystem Support"
618 depends on X86 && ACPI && PCI
623 Select to build support for Intel Low Power Subsystem such as
624 found on Intel Lynxpoint PCH. Selecting this option enables
625 things like clock tree (common clock framework) and pincontrol
626 which are needed by the LPSS peripheral drivers.
628 config X86_AMD_PLATFORM_DEVICE
629 bool "AMD ACPI2Platform devices support"
634 Select to interpret AMD specific ACPI device to platform device
635 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
636 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
637 implemented under PINCTRL subsystem.
640 tristate "Intel SoC IOSF Sideband support for SoC platforms"
643 This option enables sideband register access support for Intel SoC
644 platforms. On these platforms the IOSF sideband is used in lieu of
645 MSR's for some register accesses, mostly but not limited to thermal
646 and power. Drivers may query the availability of this device to
647 determine if they need the sideband in order to work on these
648 platforms. The sideband is available on the following SoC products.
649 This list is not meant to be exclusive.
654 You should say Y if you are running a kernel on one of these SoC's.
656 config IOSF_MBI_DEBUG
657 bool "Enable IOSF sideband access through debugfs"
658 depends on IOSF_MBI && DEBUG_FS
660 Select this option to expose the IOSF sideband access registers (MCR,
661 MDR, MCRX) through debugfs to write and read register information from
662 different units on the SoC. This is most useful for obtaining device
663 state information for debug and analysis. As this is a general access
664 mechanism, users of this option would have specific knowledge of the
665 device they want to access.
667 If you don't require the option or are in doubt, say N.
670 bool "RDC R-321x SoC"
672 depends on X86_EXTENDED_PLATFORM
674 select X86_REBOOTFIXUPS
676 This option is needed for RDC R-321x system-on-chip, also known
678 If you don't have one of these chips, you should say N here.
680 config X86_32_NON_STANDARD
681 bool "Support non-standard 32-bit SMP architectures"
682 depends on X86_32 && SMP
683 depends on X86_EXTENDED_PLATFORM
685 This option compiles in the bigsmp and STA2X11 default
686 subarchitectures. It is intended for a generic binary
687 kernel. If you select them all, kernel will probe it one by
688 one and will fallback to default.
690 # Alphabetically sorted list of Non standard 32 bit platforms
692 config X86_SUPPORTS_MEMORY_FAILURE
694 # MCE code calls memory_failure():
696 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
697 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
698 depends on X86_64 || !SPARSEMEM
699 select ARCH_SUPPORTS_MEMORY_FAILURE
702 bool "STA2X11 Companion Chip Support"
703 depends on X86_32_NON_STANDARD && PCI
704 select ARCH_HAS_PHYS_TO_DMA
705 select X86_DEV_DMA_OPS
711 This adds support for boards based on the STA2X11 IO-Hub,
712 a.k.a. "ConneXt". The chip is used in place of the standard
713 PC chipset, so all "standard" peripherals are missing. If this
714 option is selected the kernel will still be able to boot on
715 standard PC machines.
718 tristate "Eurobraille/Iris poweroff module"
721 The Iris machines from EuroBraille do not have APM or ACPI support
722 to shut themselves down properly. A special I/O sequence is
723 needed to do so, which is what this module does at
726 This is only for Iris machines from EuroBraille.
730 config SCHED_OMIT_FRAME_POINTER
732 prompt "Single-depth WCHAN output"
735 Calculate simpler /proc/<PID>/wchan values. If this option
736 is disabled then wchan values will recurse back to the
737 caller function. This provides more accurate wchan values,
738 at the expense of slightly more scheduling overhead.
740 If in doubt, say "Y".
742 menuconfig HYPERVISOR_GUEST
743 bool "Linux guest support"
745 Say Y here to enable options for running Linux under various hyper-
746 visors. This option enables basic hypervisor detection and platform
749 If you say N, all options in this submenu will be skipped and
750 disabled, and Linux guest support won't be built in.
755 bool "Enable paravirtualization code"
757 This changes the kernel so it can modify itself when it is run
758 under a hypervisor, potentially improving performance significantly
759 over full virtualization. However, when run without a hypervisor
760 the kernel is theoretically slower and slightly larger.
765 config PARAVIRT_DEBUG
766 bool "paravirt-ops debugging"
767 depends on PARAVIRT && DEBUG_KERNEL
769 Enable to debug paravirt_ops internals. Specifically, BUG if
770 a paravirt_op is missing when it is called.
772 config PARAVIRT_SPINLOCKS
773 bool "Paravirtualization layer for spinlocks"
774 depends on PARAVIRT && SMP
776 Paravirtualized spinlocks allow a pvops backend to replace the
777 spinlock implementation with something virtualization-friendly
778 (for example, block the virtual CPU rather than spinning).
780 It has a minimal impact on native kernels and gives a nice performance
781 benefit on paravirtualized KVM / Xen kernels.
783 If you are unsure how to answer this question, answer Y.
785 config QUEUED_LOCK_STAT
786 bool "Paravirt queued spinlock statistics"
787 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
789 Enable the collection of statistical data on the slowpath
790 behavior of paravirtualized queued spinlocks and report
793 source "arch/x86/xen/Kconfig"
796 bool "KVM Guest support (including kvmclock)"
798 select PARAVIRT_CLOCK
801 This option enables various optimizations for running under the KVM
802 hypervisor. It includes a paravirtualized clock, so that instead
803 of relying on a PIT (or probably other) emulation by the
804 underlying device model, the host provides the guest with
805 timing infrastructure such as time of day, and system time
808 bool "Support for running PVH guests"
810 This option enables the PVH entry point for guest virtual machines
811 as specified in the x86/HVM direct boot ABI.
814 bool "Enable debug information for KVM Guests in debugfs"
815 depends on KVM_GUEST && DEBUG_FS
817 This option enables collection of various statistics for KVM guest.
818 Statistics are displayed in debugfs filesystem. Enabling this option
819 may incur significant overhead.
821 config PARAVIRT_TIME_ACCOUNTING
822 bool "Paravirtual steal time accounting"
825 Select this option to enable fine granularity task steal time
826 accounting. Time spent executing other tasks in parallel with
827 the current vCPU is discounted from the vCPU power. To account for
828 that, there can be a small performance impact.
830 If in doubt, say N here.
832 config PARAVIRT_CLOCK
835 config JAILHOUSE_GUEST
836 bool "Jailhouse non-root cell support"
837 depends on X86_64 && PCI
840 This option allows to run Linux as guest in a Jailhouse non-root
841 cell. You can leave this option disabled if you only want to start
842 Jailhouse and run Linux afterwards in the root cell.
844 endif #HYPERVISOR_GUEST
846 source "arch/x86/Kconfig.cpu"
850 prompt "HPET Timer Support" if X86_32
852 Use the IA-PC HPET (High Precision Event Timer) to manage
853 time in preference to the PIT and RTC, if a HPET is
855 HPET is the next generation timer replacing legacy 8254s.
856 The HPET provides a stable time base on SMP
857 systems, unlike the TSC, but it is more expensive to access,
858 as it is off-chip. The interface used is documented
859 in the HPET spec, revision 1.
861 You can safely choose Y here. However, HPET will only be
862 activated if the platform and the BIOS support this feature.
863 Otherwise the 8254 will be used for timing services.
865 Choose N to continue using the legacy 8254 timer.
867 config HPET_EMULATE_RTC
869 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
872 def_bool y if X86_INTEL_MID
873 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
875 depends on X86_INTEL_MID && SFI
877 APB timer is the replacement for 8254, HPET on X86 MID platforms.
878 The APBT provides a stable time base on SMP
879 systems, unlike the TSC, but it is more expensive to access,
880 as it is off-chip. APB timers are always running regardless of CPU
881 C states, they are used as per CPU clockevent device when possible.
883 # Mark as expert because too many people got it wrong.
884 # The code disables itself when not needed.
887 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
888 bool "Enable DMI scanning" if EXPERT
890 Enabled scanning of DMI to identify machine quirks. Say Y
891 here unless you have verified that your setup is not
892 affected by entries in the DMI blacklist. Required by PNP
896 bool "Old AMD GART IOMMU support"
899 depends on X86_64 && PCI && AMD_NB
901 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
902 GART based hardware IOMMUs.
904 The GART supports full DMA access for devices with 32-bit access
905 limitations, on systems with more than 3 GB. This is usually needed
906 for USB, sound, many IDE/SATA chipsets and some other devices.
908 Newer systems typically have a modern AMD IOMMU, supported via
909 the CONFIG_AMD_IOMMU=y config option.
911 In normal configurations this driver is only active when needed:
912 there's more than 3 GB of memory and the system contains a
913 32-bit limited device.
918 bool "IBM Calgary IOMMU support"
921 depends on X86_64 && PCI
923 Support for hardware IOMMUs in IBM's xSeries x366 and x460
924 systems. Needed to run systems with more than 3GB of memory
925 properly with 32-bit PCI devices that do not support DAC
926 (Double Address Cycle). Calgary also supports bus level
927 isolation, where all DMAs pass through the IOMMU. This
928 prevents them from going anywhere except their intended
929 destination. This catches hard-to-find kernel bugs and
930 mis-behaving drivers and devices that do not use the DMA-API
931 properly to set up their DMA buffers. The IOMMU can be
932 turned off at boot time with the iommu=off parameter.
933 Normally the kernel will make the right choice by itself.
936 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
938 prompt "Should Calgary be enabled by default?"
939 depends on CALGARY_IOMMU
941 Should Calgary be enabled by default? if you choose 'y', Calgary
942 will be used (if it exists). If you choose 'n', Calgary will not be
943 used even if it exists. If you choose 'n' and would like to use
944 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
948 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
949 depends on X86_64 && SMP && DEBUG_KERNEL
950 select CPUMASK_OFFSTACK
952 Enable maximum number of CPUS and NUMA Nodes for this architecture.
956 # The maximum number of CPUs supported:
958 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
959 # and which can be configured interactively in the
960 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
962 # The ranges are different on 32-bit and 64-bit kernels, depending on
963 # hardware capabilities and scalability features of the kernel.
965 # ( If MAXSMP is enabled we just use the highest possible value and disable
966 # interactive configuration. )
969 config NR_CPUS_RANGE_BEGIN
971 default NR_CPUS_RANGE_END if MAXSMP
975 config NR_CPUS_RANGE_END
978 default 64 if SMP && X86_BIGSMP
979 default 8 if SMP && !X86_BIGSMP
982 config NR_CPUS_RANGE_END
985 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
986 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
989 config NR_CPUS_DEFAULT
992 default 32 if X86_BIGSMP
996 config NR_CPUS_DEFAULT
999 default 8192 if MAXSMP
1004 int "Maximum number of CPUs" if SMP && !MAXSMP
1005 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1006 default NR_CPUS_DEFAULT
1008 This allows you to specify the maximum number of CPUs which this
1009 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1010 supported value is 8192, otherwise the maximum value is 512. The
1011 minimum value which makes sense is 2.
1013 This is purely to save memory: each supported CPU adds about 8KB
1014 to the kernel image.
1021 prompt "Multi-core scheduler support"
1024 Multi-core scheduler support improves the CPU scheduler's decision
1025 making when dealing with multi-core CPU chips at a cost of slightly
1026 increased overhead in some places. If unsure say N here.
1028 config SCHED_MC_PRIO
1029 bool "CPU core priorities scheduler support"
1030 depends on SCHED_MC && CPU_SUP_INTEL
1031 select X86_INTEL_PSTATE
1035 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1036 core ordering determined at manufacturing time, which allows
1037 certain cores to reach higher turbo frequencies (when running
1038 single threaded workloads) than others.
1040 Enabling this kernel feature teaches the scheduler about
1041 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1042 scheduler's CPU selection logic accordingly, so that higher
1043 overall system performance can be achieved.
1045 This feature will have no effect on CPUs without this feature.
1047 If unsure say Y here.
1051 depends on !SMP && X86_LOCAL_APIC
1054 bool "Local APIC support on uniprocessors" if !PCI_MSI
1056 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1058 A local APIC (Advanced Programmable Interrupt Controller) is an
1059 integrated interrupt controller in the CPU. If you have a single-CPU
1060 system which has a processor with a local APIC, you can say Y here to
1061 enable and use it. If you say Y here even though your machine doesn't
1062 have a local APIC, then the kernel will still run with no slowdown at
1063 all. The local APIC supports CPU-generated self-interrupts (timer,
1064 performance counters), and the NMI watchdog which detects hard
1067 config X86_UP_IOAPIC
1068 bool "IO-APIC support on uniprocessors"
1069 depends on X86_UP_APIC
1071 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1072 SMP-capable replacement for PC-style interrupt controllers. Most
1073 SMP systems and many recent uniprocessor systems have one.
1075 If you have a single-CPU system with an IO-APIC, you can say Y here
1076 to use it. If you say Y here even though your machine doesn't have
1077 an IO-APIC, then the kernel will still run with no slowdown at all.
1079 config X86_LOCAL_APIC
1081 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1082 select IRQ_DOMAIN_HIERARCHY
1083 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1087 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1089 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1090 bool "Reroute for broken boot IRQs"
1091 depends on X86_IO_APIC
1093 This option enables a workaround that fixes a source of
1094 spurious interrupts. This is recommended when threaded
1095 interrupt handling is used on systems where the generation of
1096 superfluous "boot interrupts" cannot be disabled.
1098 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1099 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1100 kernel does during interrupt handling). On chipsets where this
1101 boot IRQ generation cannot be disabled, this workaround keeps
1102 the original IRQ line masked so that only the equivalent "boot
1103 IRQ" is delivered to the CPUs. The workaround also tells the
1104 kernel to set up the IRQ handler on the boot IRQ line. In this
1105 way only one interrupt is delivered to the kernel. Otherwise
1106 the spurious second interrupt may cause the kernel to bring
1107 down (vital) interrupt lines.
1109 Only affects "broken" chipsets. Interrupt sharing may be
1110 increased on these systems.
1113 bool "Machine Check / overheating reporting"
1114 select GENERIC_ALLOCATOR
1117 Machine Check support allows the processor to notify the
1118 kernel if it detects a problem (e.g. overheating, data corruption).
1119 The action the kernel takes depends on the severity of the problem,
1120 ranging from warning messages to halting the machine.
1122 config X86_MCELOG_LEGACY
1123 bool "Support for deprecated /dev/mcelog character device"
1126 Enable support for /dev/mcelog which is needed by the old mcelog
1127 userspace logging daemon. Consider switching to the new generation
1130 config X86_MCE_INTEL
1132 prompt "Intel MCE features"
1133 depends on X86_MCE && X86_LOCAL_APIC
1135 Additional support for intel specific MCE features such as
1136 the thermal monitor.
1140 prompt "AMD MCE features"
1141 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1143 Additional support for AMD specific MCE features such as
1144 the DRAM Error Threshold.
1146 config X86_ANCIENT_MCE
1147 bool "Support for old Pentium 5 / WinChip machine checks"
1148 depends on X86_32 && X86_MCE
1150 Include support for machine check handling on old Pentium 5 or WinChip
1151 systems. These typically need to be enabled explicitly on the command
1154 config X86_MCE_THRESHOLD
1155 depends on X86_MCE_AMD || X86_MCE_INTEL
1158 config X86_MCE_INJECT
1159 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1160 tristate "Machine check injector support"
1162 Provide support for injecting machine checks for testing purposes.
1163 If you don't know what a machine check is and you don't do kernel
1164 QA it is safe to say n.
1166 config X86_THERMAL_VECTOR
1168 depends on X86_MCE_INTEL
1170 source "arch/x86/events/Kconfig"
1172 config X86_LEGACY_VM86
1173 bool "Legacy VM86 support"
1176 This option allows user programs to put the CPU into V8086
1177 mode, which is an 80286-era approximation of 16-bit real mode.
1179 Some very old versions of X and/or vbetool require this option
1180 for user mode setting. Similarly, DOSEMU will use it if
1181 available to accelerate real mode DOS programs. However, any
1182 recent version of DOSEMU, X, or vbetool should be fully
1183 functional even without kernel VM86 support, as they will all
1184 fall back to software emulation. Nevertheless, if you are using
1185 a 16-bit DOS program where 16-bit performance matters, vm86
1186 mode might be faster than emulation and you might want to
1189 Note that any app that works on a 64-bit kernel is unlikely to
1190 need this option, as 64-bit kernels don't, and can't, support
1191 V8086 mode. This option is also unrelated to 16-bit protected
1192 mode and is not needed to run most 16-bit programs under Wine.
1194 Enabling this option increases the complexity of the kernel
1195 and slows down exception handling a tiny bit.
1197 If unsure, say N here.
1201 default X86_LEGACY_VM86
1204 bool "Enable support for 16-bit segments" if EXPERT
1206 depends on MODIFY_LDT_SYSCALL
1208 This option is required by programs like Wine to run 16-bit
1209 protected mode legacy code on x86 processors. Disabling
1210 this option saves about 300 bytes on i386, or around 6K text
1211 plus 16K runtime memory on x86-64,
1215 depends on X86_16BIT && X86_32
1219 depends on X86_16BIT && X86_64
1221 config X86_VSYSCALL_EMULATION
1222 bool "Enable vsyscall emulation" if EXPERT
1226 This enables emulation of the legacy vsyscall page. Disabling
1227 it is roughly equivalent to booting with vsyscall=none, except
1228 that it will also disable the helpful warning if a program
1229 tries to use a vsyscall. With this option set to N, offending
1230 programs will just segfault, citing addresses of the form
1233 This option is required by many programs built before 2013, and
1234 care should be used even with newer programs if set to N.
1236 Disabling this option saves about 7K of kernel size and
1237 possibly 4K of additional runtime pagetable memory.
1240 tristate "Toshiba Laptop support"
1243 This adds a driver to safely access the System Management Mode of
1244 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1245 not work on models with a Phoenix BIOS. The System Management Mode
1246 is used to set the BIOS and power saving options on Toshiba portables.
1248 For information on utilities to make use of this driver see the
1249 Toshiba Linux utilities web site at:
1250 <http://www.buzzard.org.uk/toshiba/>.
1252 Say Y if you intend to run this kernel on a Toshiba portable.
1256 tristate "Dell i8k legacy laptop support"
1258 select SENSORS_DELL_SMM
1260 This option enables legacy /proc/i8k userspace interface in hwmon
1261 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1262 temperature and allows controlling fan speeds of Dell laptops via
1263 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1264 it reports also power and hotkey status. For fan speed control is
1265 needed userspace package i8kutils.
1267 Say Y if you intend to run this kernel on old Dell laptops or want to
1268 use userspace package i8kutils.
1271 config X86_REBOOTFIXUPS
1272 bool "Enable X86 board specific fixups for reboot"
1275 This enables chipset and/or board specific fixups to be done
1276 in order to get reboot to work correctly. This is only needed on
1277 some combinations of hardware and BIOS. The symptom, for which
1278 this config is intended, is when reboot ends with a stalled/hung
1281 Currently, the only fixup is for the Geode machines using
1282 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1284 Say Y if you want to enable the fixup. Currently, it's safe to
1285 enable this option even if you don't need it.
1289 bool "CPU microcode loading support"
1291 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1294 If you say Y here, you will be able to update the microcode on
1295 Intel and AMD processors. The Intel support is for the IA32 family,
1296 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1297 AMD support is for families 0x10 and later. You will obviously need
1298 the actual microcode binary data itself which is not shipped with
1301 The preferred method to load microcode from a detached initrd is described
1302 in Documentation/x86/microcode.txt. For that you need to enable
1303 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1304 initrd for microcode blobs.
1306 In addition, you can build the microcode into the kernel. For that you
1307 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1310 config MICROCODE_INTEL
1311 bool "Intel microcode loading support"
1312 depends on MICROCODE
1316 This options enables microcode patch loading support for Intel
1319 For the current Intel microcode data package go to
1320 <https://downloadcenter.intel.com> and search for
1321 'Linux Processor Microcode Data File'.
1323 config MICROCODE_AMD
1324 bool "AMD microcode loading support"
1325 depends on MICROCODE
1328 If you select this option, microcode patch loading support for AMD
1329 processors will be enabled.
1331 config MICROCODE_OLD_INTERFACE
1333 depends on MICROCODE
1336 tristate "/dev/cpu/*/msr - Model-specific register support"
1338 This device gives privileged processes access to the x86
1339 Model-Specific Registers (MSRs). It is a character device with
1340 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1341 MSR accesses are directed to a specific CPU on multi-processor
1345 tristate "/dev/cpu/*/cpuid - CPU information support"
1347 This device gives processes access to the x86 CPUID instruction to
1348 be executed on a specific processor. It is a character device
1349 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1353 prompt "High Memory Support"
1360 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1361 However, the address space of 32-bit x86 processors is only 4
1362 Gigabytes large. That means that, if you have a large amount of
1363 physical memory, not all of it can be "permanently mapped" by the
1364 kernel. The physical memory that's not permanently mapped is called
1367 If you are compiling a kernel which will never run on a machine with
1368 more than 1 Gigabyte total physical RAM, answer "off" here (default
1369 choice and suitable for most users). This will result in a "3GB/1GB"
1370 split: 3GB are mapped so that each process sees a 3GB virtual memory
1371 space and the remaining part of the 4GB virtual memory space is used
1372 by the kernel to permanently map as much physical memory as
1375 If the machine has between 1 and 4 Gigabytes physical RAM, then
1378 If more than 4 Gigabytes is used then answer "64GB" here. This
1379 selection turns Intel PAE (Physical Address Extension) mode on.
1380 PAE implements 3-level paging on IA32 processors. PAE is fully
1381 supported by Linux, PAE mode is implemented on all recent Intel
1382 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1383 then the kernel will not boot on CPUs that don't support PAE!
1385 The actual amount of total physical memory will either be
1386 auto detected or can be forced by using a kernel command line option
1387 such as "mem=256M". (Try "man bootparam" or see the documentation of
1388 your boot loader (lilo or loadlin) about how to pass options to the
1389 kernel at boot time.)
1391 If unsure, say "off".
1396 Select this if you have a 32-bit processor and between 1 and 4
1397 gigabytes of physical RAM.
1401 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1404 Select this if you have a 32-bit processor and more than 4
1405 gigabytes of physical RAM.
1410 prompt "Memory split" if EXPERT
1414 Select the desired split between kernel and user memory.
1416 If the address range available to the kernel is less than the
1417 physical memory installed, the remaining memory will be available
1418 as "high memory". Accessing high memory is a little more costly
1419 than low memory, as it needs to be mapped into the kernel first.
1420 Note that increasing the kernel address space limits the range
1421 available to user programs, making the address space there
1422 tighter. Selecting anything other than the default 3G/1G split
1423 will also likely make your kernel incompatible with binary-only
1426 If you are not absolutely sure what you are doing, leave this
1430 bool "3G/1G user/kernel split"
1431 config VMSPLIT_3G_OPT
1433 bool "3G/1G user/kernel split (for full 1G low memory)"
1435 bool "2G/2G user/kernel split"
1436 config VMSPLIT_2G_OPT
1438 bool "2G/2G user/kernel split (for full 2G low memory)"
1440 bool "1G/3G user/kernel split"
1445 default 0xB0000000 if VMSPLIT_3G_OPT
1446 default 0x80000000 if VMSPLIT_2G
1447 default 0x78000000 if VMSPLIT_2G_OPT
1448 default 0x40000000 if VMSPLIT_1G
1454 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1457 bool "PAE (Physical Address Extension) Support"
1458 depends on X86_32 && !HIGHMEM4G
1459 select PHYS_ADDR_T_64BIT
1462 PAE is required for NX support, and furthermore enables
1463 larger swapspace support for non-overcommit purposes. It
1464 has the cost of more pagetable lookup overhead, and also
1465 consumes more pagetable space per process.
1468 bool "Enable 5-level page tables support"
1469 select DYNAMIC_MEMORY_LAYOUT
1470 select SPARSEMEM_VMEMMAP
1473 5-level paging enables access to larger address space:
1474 upto 128 PiB of virtual address space and 4 PiB of
1475 physical address space.
1477 It will be supported by future Intel CPUs.
1479 A kernel with the option enabled can be booted on machines that
1480 support 4- or 5-level paging.
1482 See Documentation/x86/x86_64/5level-paging.txt for more
1487 config X86_DIRECT_GBPAGES
1489 depends on X86_64 && !DEBUG_PAGEALLOC
1491 Certain kernel features effectively disable kernel
1492 linear 1 GB mappings (even if the CPU otherwise
1493 supports them), so don't confuse the user by printing
1494 that we have them enabled.
1496 config X86_CPA_STATISTICS
1497 bool "Enable statistic for Change Page Attribute"
1500 Expose statistics about the Change Page Attribute mechanims, which
1501 helps to determine the effectivness of preserving large and huge
1502 page mappings when mapping protections are changed.
1504 config ARCH_HAS_MEM_ENCRYPT
1507 config AMD_MEM_ENCRYPT
1508 bool "AMD Secure Memory Encryption (SME) support"
1509 depends on X86_64 && CPU_SUP_AMD
1510 select DYNAMIC_PHYSICAL_MASK
1511 select ARCH_USE_MEMREMAP_PROT
1513 Say yes to enable support for the encryption of system memory.
1514 This requires an AMD processor that supports Secure Memory
1517 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1518 bool "Activate AMD Secure Memory Encryption (SME) by default"
1520 depends on AMD_MEM_ENCRYPT
1522 Say yes to have system memory encrypted by default if running on
1523 an AMD processor that supports Secure Memory Encryption (SME).
1525 If set to Y, then the encryption of system memory can be
1526 deactivated with the mem_encrypt=off command line option.
1528 If set to N, then the encryption of system memory can be
1529 activated with the mem_encrypt=on command line option.
1531 # Common NUMA Features
1533 bool "Numa Memory Allocation and Scheduler Support"
1535 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1536 default y if X86_BIGSMP
1538 Enable NUMA (Non Uniform Memory Access) support.
1540 The kernel will try to allocate memory used by a CPU on the
1541 local memory controller of the CPU and add some more
1542 NUMA awareness to the kernel.
1544 For 64-bit this is recommended if the system is Intel Core i7
1545 (or later), AMD Opteron, or EM64T NUMA.
1547 For 32-bit this is only needed if you boot a 32-bit
1548 kernel on a 64-bit NUMA platform.
1550 Otherwise, you should say N.
1554 prompt "Old style AMD Opteron NUMA detection"
1555 depends on X86_64 && NUMA && PCI
1557 Enable AMD NUMA node topology detection. You should say Y here if
1558 you have a multi processor AMD system. This uses an old method to
1559 read the NUMA configuration directly from the builtin Northbridge
1560 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1561 which also takes priority if both are compiled in.
1563 config X86_64_ACPI_NUMA
1565 prompt "ACPI NUMA detection"
1566 depends on X86_64 && NUMA && ACPI && PCI
1569 Enable ACPI SRAT based node topology detection.
1571 # Some NUMA nodes have memory ranges that span
1572 # other nodes. Even though a pfn is valid and
1573 # between a node's start and end pfns, it may not
1574 # reside on that node. See memmap_init_zone()
1576 config NODES_SPAN_OTHER_NODES
1578 depends on X86_64_ACPI_NUMA
1581 bool "NUMA emulation"
1584 Enable NUMA emulation. A flat machine will be split
1585 into virtual nodes when booted with "numa=fake=N", where N is the
1586 number of nodes. This is only useful for debugging.
1589 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1591 default "10" if MAXSMP
1592 default "6" if X86_64
1594 depends on NEED_MULTIPLE_NODES
1596 Specify the maximum number of NUMA Nodes available on the target
1597 system. Increases memory reserved to accommodate various tables.
1599 config ARCH_HAVE_MEMORY_PRESENT
1601 depends on X86_32 && DISCONTIGMEM
1603 config ARCH_FLATMEM_ENABLE
1605 depends on X86_32 && !NUMA
1607 config ARCH_DISCONTIGMEM_ENABLE
1609 depends on NUMA && X86_32
1611 config ARCH_DISCONTIGMEM_DEFAULT
1613 depends on NUMA && X86_32
1615 config ARCH_SPARSEMEM_ENABLE
1617 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1618 select SPARSEMEM_STATIC if X86_32
1619 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1621 config ARCH_SPARSEMEM_DEFAULT
1625 config ARCH_SELECT_MEMORY_MODEL
1627 depends on ARCH_SPARSEMEM_ENABLE
1629 config ARCH_MEMORY_PROBE
1630 bool "Enable sysfs memory/probe interface"
1631 depends on X86_64 && MEMORY_HOTPLUG
1633 This option enables a sysfs memory/probe interface for testing.
1634 See Documentation/memory-hotplug.txt for more information.
1635 If you are unsure how to answer this question, answer N.
1637 config ARCH_PROC_KCORE_TEXT
1639 depends on X86_64 && PROC_KCORE
1641 config ILLEGAL_POINTER_VALUE
1644 default 0xdead000000000000 if X86_64
1646 config X86_PMEM_LEGACY_DEVICE
1649 config X86_PMEM_LEGACY
1650 tristate "Support non-standard NVDIMMs and ADR protected memory"
1651 depends on PHYS_ADDR_T_64BIT
1653 select X86_PMEM_LEGACY_DEVICE
1656 Treat memory marked using the non-standard e820 type of 12 as used
1657 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1658 The kernel will offer these regions to the 'pmem' driver so
1659 they can be used for persistent storage.
1664 bool "Allocate 3rd-level pagetables from highmem"
1667 The VM uses one page table entry for each page of physical memory.
1668 For systems with a lot of RAM, this can be wasteful of precious
1669 low memory. Setting this option will put user-space page table
1670 entries in high memory.
1672 config X86_CHECK_BIOS_CORRUPTION
1673 bool "Check for low memory corruption"
1675 Periodically check for memory corruption in low memory, which
1676 is suspected to be caused by BIOS. Even when enabled in the
1677 configuration, it is disabled at runtime. Enable it by
1678 setting "memory_corruption_check=1" on the kernel command
1679 line. By default it scans the low 64k of memory every 60
1680 seconds; see the memory_corruption_check_size and
1681 memory_corruption_check_period parameters in
1682 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1684 When enabled with the default parameters, this option has
1685 almost no overhead, as it reserves a relatively small amount
1686 of memory and scans it infrequently. It both detects corruption
1687 and prevents it from affecting the running system.
1689 It is, however, intended as a diagnostic tool; if repeatable
1690 BIOS-originated corruption always affects the same memory,
1691 you can use memmap= to prevent the kernel from using that
1694 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1695 bool "Set the default setting of memory_corruption_check"
1696 depends on X86_CHECK_BIOS_CORRUPTION
1699 Set whether the default state of memory_corruption_check is
1702 config X86_RESERVE_LOW
1703 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1707 Specify the amount of low memory to reserve for the BIOS.
1709 The first page contains BIOS data structures that the kernel
1710 must not use, so that page must always be reserved.
1712 By default we reserve the first 64K of physical RAM, as a
1713 number of BIOSes are known to corrupt that memory range
1714 during events such as suspend/resume or monitor cable
1715 insertion, so it must not be used by the kernel.
1717 You can set this to 4 if you are absolutely sure that you
1718 trust the BIOS to get all its memory reservations and usages
1719 right. If you know your BIOS have problems beyond the
1720 default 64K area, you can set this to 640 to avoid using the
1721 entire low memory range.
1723 If you have doubts about the BIOS (e.g. suspend/resume does
1724 not work or there's kernel crashes after certain hardware
1725 hotplug events) then you might want to enable
1726 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1727 typical corruption patterns.
1729 Leave this to the default value of 64 if you are unsure.
1731 config MATH_EMULATION
1733 depends on MODIFY_LDT_SYSCALL
1734 prompt "Math emulation" if X86_32
1736 Linux can emulate a math coprocessor (used for floating point
1737 operations) if you don't have one. 486DX and Pentium processors have
1738 a math coprocessor built in, 486SX and 386 do not, unless you added
1739 a 487DX or 387, respectively. (The messages during boot time can
1740 give you some hints here ["man dmesg"].) Everyone needs either a
1741 coprocessor or this emulation.
1743 If you don't have a math coprocessor, you need to say Y here; if you
1744 say Y here even though you have a coprocessor, the coprocessor will
1745 be used nevertheless. (This behavior can be changed with the kernel
1746 command line option "no387", which comes handy if your coprocessor
1747 is broken. Try "man bootparam" or see the documentation of your boot
1748 loader (lilo or loadlin) about how to pass options to the kernel at
1749 boot time.) This means that it is a good idea to say Y here if you
1750 intend to use this kernel on different machines.
1752 More information about the internals of the Linux math coprocessor
1753 emulation can be found in <file:arch/x86/math-emu/README>.
1755 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1756 kernel, it won't hurt.
1760 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1762 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1763 the Memory Type Range Registers (MTRRs) may be used to control
1764 processor access to memory ranges. This is most useful if you have
1765 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1766 allows bus write transfers to be combined into a larger transfer
1767 before bursting over the PCI/AGP bus. This can increase performance
1768 of image write operations 2.5 times or more. Saying Y here creates a
1769 /proc/mtrr file which may be used to manipulate your processor's
1770 MTRRs. Typically the X server should use this.
1772 This code has a reasonably generic interface so that similar
1773 control registers on other processors can be easily supported
1776 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1777 Registers (ARRs) which provide a similar functionality to MTRRs. For
1778 these, the ARRs are used to emulate the MTRRs.
1779 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1780 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1781 write-combining. All of these processors are supported by this code
1782 and it makes sense to say Y here if you have one of them.
1784 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1785 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1786 can lead to all sorts of problems, so it's good to say Y here.
1788 You can safely say Y even if your machine doesn't have MTRRs, you'll
1789 just add about 9 KB to your kernel.
1791 See <file:Documentation/x86/mtrr.txt> for more information.
1793 config MTRR_SANITIZER
1795 prompt "MTRR cleanup support"
1798 Convert MTRR layout from continuous to discrete, so X drivers can
1799 add writeback entries.
1801 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1802 The largest mtrr entry size for a continuous block can be set with
1807 config MTRR_SANITIZER_ENABLE_DEFAULT
1808 int "MTRR cleanup enable value (0-1)"
1811 depends on MTRR_SANITIZER
1813 Enable mtrr cleanup default value
1815 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1816 int "MTRR cleanup spare reg num (0-7)"
1819 depends on MTRR_SANITIZER
1821 mtrr cleanup spare entries default, it can be changed via
1822 mtrr_spare_reg_nr=N on the kernel command line.
1826 prompt "x86 PAT support" if EXPERT
1829 Use PAT attributes to setup page level cache control.
1831 PATs are the modern equivalents of MTRRs and are much more
1832 flexible than MTRRs.
1834 Say N here if you see bootup problems (boot crash, boot hang,
1835 spontaneous reboots) or a non-working video driver.
1839 config ARCH_USES_PG_UNCACHED
1845 prompt "x86 architectural random number generator" if EXPERT
1847 Enable the x86 architectural RDRAND instruction
1848 (Intel Bull Mountain technology) to generate random numbers.
1849 If supported, this is a high bandwidth, cryptographically
1850 secure hardware random number generator.
1854 prompt "Supervisor Mode Access Prevention" if EXPERT
1856 Supervisor Mode Access Prevention (SMAP) is a security
1857 feature in newer Intel processors. There is a small
1858 performance cost if this enabled and turned on; there is
1859 also a small increase in the kernel size if this is enabled.
1863 config X86_INTEL_UMIP
1865 depends on CPU_SUP_INTEL
1866 prompt "Intel User Mode Instruction Prevention" if EXPERT
1868 The User Mode Instruction Prevention (UMIP) is a security
1869 feature in newer Intel processors. If enabled, a general
1870 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1871 or STR instructions are executed in user mode. These instructions
1872 unnecessarily expose information about the hardware state.
1874 The vast majority of applications do not use these instructions.
1875 For the very few that do, software emulation is provided in
1876 specific cases in protected and virtual-8086 modes. Emulated
1879 config X86_INTEL_MPX
1880 prompt "Intel MPX (Memory Protection Extensions)"
1882 # Note: only available in 64-bit mode due to VMA flags shortage
1883 depends on CPU_SUP_INTEL && X86_64
1884 select ARCH_USES_HIGH_VMA_FLAGS
1886 MPX provides hardware features that can be used in
1887 conjunction with compiler-instrumented code to check
1888 memory references. It is designed to detect buffer
1889 overflow or underflow bugs.
1891 This option enables running applications which are
1892 instrumented or otherwise use MPX. It does not use MPX
1893 itself inside the kernel or to protect the kernel
1894 against bad memory references.
1896 Enabling this option will make the kernel larger:
1897 ~8k of kernel text and 36 bytes of data on a 64-bit
1898 defconfig. It adds a long to the 'mm_struct' which
1899 will increase the kernel memory overhead of each
1900 process and adds some branches to paths used during
1901 exec() and munmap().
1903 For details, see Documentation/x86/intel_mpx.txt
1907 config X86_INTEL_MEMORY_PROTECTION_KEYS
1908 prompt "Intel Memory Protection Keys"
1910 # Note: only available in 64-bit mode
1911 depends on CPU_SUP_INTEL && X86_64
1912 select ARCH_USES_HIGH_VMA_FLAGS
1913 select ARCH_HAS_PKEYS
1915 Memory Protection Keys provides a mechanism for enforcing
1916 page-based protections, but without requiring modification of the
1917 page tables when an application changes protection domains.
1919 For details, see Documentation/x86/protection-keys.txt
1924 bool "EFI runtime service support"
1927 select EFI_RUNTIME_WRAPPERS
1929 This enables the kernel to use EFI runtime services that are
1930 available (such as the EFI variable services).
1932 This option is only useful on systems that have EFI firmware.
1933 In addition, you should use the latest ELILO loader available
1934 at <http://elilo.sourceforge.net> in order to take advantage
1935 of EFI runtime services. However, even with this option, the
1936 resultant kernel should continue to boot on existing non-EFI
1940 bool "EFI stub support"
1941 depends on EFI && !X86_USE_3DNOW
1944 This kernel feature allows a bzImage to be loaded directly
1945 by EFI firmware without the use of a bootloader.
1947 See Documentation/efi-stub.txt for more information.
1950 bool "EFI mixed-mode support"
1951 depends on EFI_STUB && X86_64
1953 Enabling this feature allows a 64-bit kernel to be booted
1954 on a 32-bit firmware, provided that your CPU supports 64-bit
1957 Note that it is not possible to boot a mixed-mode enabled
1958 kernel via the EFI boot stub - a bootloader that supports
1959 the EFI handover protocol must be used.
1965 prompt "Enable seccomp to safely compute untrusted bytecode"
1967 This kernel feature is useful for number crunching applications
1968 that may need to compute untrusted bytecode during their
1969 execution. By using pipes or other transports made available to
1970 the process as file descriptors supporting the read/write
1971 syscalls, it's possible to isolate those applications in
1972 their own address space using seccomp. Once seccomp is
1973 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1974 and the task is only allowed to execute a few safe syscalls
1975 defined by each seccomp mode.
1977 If unsure, say Y. Only embedded should say N here.
1979 source "kernel/Kconfig.hz"
1982 bool "kexec system call"
1985 kexec is a system call that implements the ability to shutdown your
1986 current kernel, and to start another kernel. It is like a reboot
1987 but it is independent of the system firmware. And like a reboot
1988 you can start any kernel with it, not just Linux.
1990 The name comes from the similarity to the exec system call.
1992 It is an ongoing process to be certain the hardware in a machine
1993 is properly shutdown, so do not be surprised if this code does not
1994 initially work for you. As of this writing the exact hardware
1995 interface is strongly in flux, so no good recommendation can be
1999 bool "kexec file based system call"
2004 depends on CRYPTO_SHA256=y
2006 This is new version of kexec system call. This system call is
2007 file based and takes file descriptors as system call argument
2008 for kernel and initramfs as opposed to list of segments as
2009 accepted by previous system call.
2011 config ARCH_HAS_KEXEC_PURGATORY
2014 config KEXEC_VERIFY_SIG
2015 bool "Verify kernel signature during kexec_file_load() syscall"
2016 depends on KEXEC_FILE
2018 This option makes kernel signature verification mandatory for
2019 the kexec_file_load() syscall.
2021 In addition to that option, you need to enable signature
2022 verification for the corresponding kernel image type being
2023 loaded in order for this to work.
2025 config KEXEC_BZIMAGE_VERIFY_SIG
2026 bool "Enable bzImage signature verification support"
2027 depends on KEXEC_VERIFY_SIG
2028 depends on SIGNED_PE_FILE_VERIFICATION
2029 select SYSTEM_TRUSTED_KEYRING
2031 Enable bzImage signature verification support.
2034 bool "kernel crash dumps"
2035 depends on X86_64 || (X86_32 && HIGHMEM)
2037 Generate crash dump after being started by kexec.
2038 This should be normally only set in special crash dump kernels
2039 which are loaded in the main kernel with kexec-tools into
2040 a specially reserved region and then later executed after
2041 a crash by kdump/kexec. The crash dump kernel must be compiled
2042 to a memory address not used by the main kernel or BIOS using
2043 PHYSICAL_START, or it must be built as a relocatable image
2044 (CONFIG_RELOCATABLE=y).
2045 For more details see Documentation/kdump/kdump.txt
2049 depends on KEXEC && HIBERNATION
2051 Jump between original kernel and kexeced kernel and invoke
2052 code in physical address mode via KEXEC
2054 config PHYSICAL_START
2055 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2058 This gives the physical address where the kernel is loaded.
2060 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2061 bzImage will decompress itself to above physical address and
2062 run from there. Otherwise, bzImage will run from the address where
2063 it has been loaded by the boot loader and will ignore above physical
2066 In normal kdump cases one does not have to set/change this option
2067 as now bzImage can be compiled as a completely relocatable image
2068 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2069 address. This option is mainly useful for the folks who don't want
2070 to use a bzImage for capturing the crash dump and want to use a
2071 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2072 to be specifically compiled to run from a specific memory area
2073 (normally a reserved region) and this option comes handy.
2075 So if you are using bzImage for capturing the crash dump,
2076 leave the value here unchanged to 0x1000000 and set
2077 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2078 for capturing the crash dump change this value to start of
2079 the reserved region. In other words, it can be set based on
2080 the "X" value as specified in the "crashkernel=YM@XM"
2081 command line boot parameter passed to the panic-ed
2082 kernel. Please take a look at Documentation/kdump/kdump.txt
2083 for more details about crash dumps.
2085 Usage of bzImage for capturing the crash dump is recommended as
2086 one does not have to build two kernels. Same kernel can be used
2087 as production kernel and capture kernel. Above option should have
2088 gone away after relocatable bzImage support is introduced. But it
2089 is present because there are users out there who continue to use
2090 vmlinux for dump capture. This option should go away down the
2093 Don't change this unless you know what you are doing.
2096 bool "Build a relocatable kernel"
2099 This builds a kernel image that retains relocation information
2100 so it can be loaded someplace besides the default 1MB.
2101 The relocations tend to make the kernel binary about 10% larger,
2102 but are discarded at runtime.
2104 One use is for the kexec on panic case where the recovery kernel
2105 must live at a different physical address than the primary
2108 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2109 it has been loaded at and the compile time physical address
2110 (CONFIG_PHYSICAL_START) is used as the minimum location.
2112 config RANDOMIZE_BASE
2113 bool "Randomize the address of the kernel image (KASLR)"
2114 depends on RELOCATABLE
2117 In support of Kernel Address Space Layout Randomization (KASLR),
2118 this randomizes the physical address at which the kernel image
2119 is decompressed and the virtual address where the kernel
2120 image is mapped, as a security feature that deters exploit
2121 attempts relying on knowledge of the location of kernel
2124 On 64-bit, the kernel physical and virtual addresses are
2125 randomized separately. The physical address will be anywhere
2126 between 16MB and the top of physical memory (up to 64TB). The
2127 virtual address will be randomized from 16MB up to 1GB (9 bits
2128 of entropy). Note that this also reduces the memory space
2129 available to kernel modules from 1.5GB to 1GB.
2131 On 32-bit, the kernel physical and virtual addresses are
2132 randomized together. They will be randomized from 16MB up to
2133 512MB (8 bits of entropy).
2135 Entropy is generated using the RDRAND instruction if it is
2136 supported. If RDTSC is supported, its value is mixed into
2137 the entropy pool as well. If neither RDRAND nor RDTSC are
2138 supported, then entropy is read from the i8254 timer. The
2139 usable entropy is limited by the kernel being built using
2140 2GB addressing, and that PHYSICAL_ALIGN must be at a
2141 minimum of 2MB. As a result, only 10 bits of entropy are
2142 theoretically possible, but the implementations are further
2143 limited due to memory layouts.
2147 # Relocation on x86 needs some additional build support
2148 config X86_NEED_RELOCS
2150 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2152 config PHYSICAL_ALIGN
2153 hex "Alignment value to which kernel should be aligned"
2155 range 0x2000 0x1000000 if X86_32
2156 range 0x200000 0x1000000 if X86_64
2158 This value puts the alignment restrictions on physical address
2159 where kernel is loaded and run from. Kernel is compiled for an
2160 address which meets above alignment restriction.
2162 If bootloader loads the kernel at a non-aligned address and
2163 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2164 address aligned to above value and run from there.
2166 If bootloader loads the kernel at a non-aligned address and
2167 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2168 load address and decompress itself to the address it has been
2169 compiled for and run from there. The address for which kernel is
2170 compiled already meets above alignment restrictions. Hence the
2171 end result is that kernel runs from a physical address meeting
2172 above alignment restrictions.
2174 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2175 this value must be a multiple of 0x200000.
2177 Don't change this unless you know what you are doing.
2179 config DYNAMIC_MEMORY_LAYOUT
2182 This option makes base addresses of vmalloc and vmemmap as well as
2183 __PAGE_OFFSET movable during boot.
2185 config RANDOMIZE_MEMORY
2186 bool "Randomize the kernel memory sections"
2188 depends on RANDOMIZE_BASE
2189 select DYNAMIC_MEMORY_LAYOUT
2190 default RANDOMIZE_BASE
2192 Randomizes the base virtual address of kernel memory sections
2193 (physical memory mapping, vmalloc & vmemmap). This security feature
2194 makes exploits relying on predictable memory locations less reliable.
2196 The order of allocations remains unchanged. Entropy is generated in
2197 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2198 configuration have in average 30,000 different possible virtual
2199 addresses for each memory section.
2203 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2204 hex "Physical memory mapping padding" if EXPERT
2205 depends on RANDOMIZE_MEMORY
2206 default "0xa" if MEMORY_HOTPLUG
2208 range 0x1 0x40 if MEMORY_HOTPLUG
2211 Define the padding in terabytes added to the existing physical
2212 memory size during kernel memory randomization. It is useful
2213 for memory hotplug support but reduces the entropy available for
2214 address randomization.
2216 If unsure, leave at the default value.
2222 config BOOTPARAM_HOTPLUG_CPU0
2223 bool "Set default setting of cpu0_hotpluggable"
2224 depends on HOTPLUG_CPU
2226 Set whether default state of cpu0_hotpluggable is on or off.
2228 Say Y here to enable CPU0 hotplug by default. If this switch
2229 is turned on, there is no need to give cpu0_hotplug kernel
2230 parameter and the CPU0 hotplug feature is enabled by default.
2232 Please note: there are two known CPU0 dependencies if you want
2233 to enable the CPU0 hotplug feature either by this switch or by
2234 cpu0_hotplug kernel parameter.
2236 First, resume from hibernate or suspend always starts from CPU0.
2237 So hibernate and suspend are prevented if CPU0 is offline.
2239 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2240 offline if any interrupt can not migrate out of CPU0. There may
2241 be other CPU0 dependencies.
2243 Please make sure the dependencies are under your control before
2244 you enable this feature.
2246 Say N if you don't want to enable CPU0 hotplug feature by default.
2247 You still can enable the CPU0 hotplug feature at boot by kernel
2248 parameter cpu0_hotplug.
2250 config DEBUG_HOTPLUG_CPU0
2252 prompt "Debug CPU0 hotplug"
2253 depends on HOTPLUG_CPU
2255 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2256 soon as possible and boots up userspace with CPU0 offlined. User
2257 can online CPU0 back after boot time.
2259 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2260 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2261 compilation or giving cpu0_hotplug kernel parameter at boot.
2267 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2268 depends on COMPAT_32
2270 Certain buggy versions of glibc will crash if they are
2271 presented with a 32-bit vDSO that is not mapped at the address
2272 indicated in its segment table.
2274 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2275 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2276 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2277 the only released version with the bug, but OpenSUSE 9
2278 contains a buggy "glibc 2.3.2".
2280 The symptom of the bug is that everything crashes on startup, saying:
2281 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2283 Saying Y here changes the default value of the vdso32 boot
2284 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2285 This works around the glibc bug but hurts performance.
2287 If unsure, say N: if you are compiling your own kernel, you
2288 are unlikely to be using a buggy version of glibc.
2291 prompt "vsyscall table for legacy applications"
2293 default LEGACY_VSYSCALL_EMULATE
2295 Legacy user code that does not know how to find the vDSO expects
2296 to be able to issue three syscalls by calling fixed addresses in
2297 kernel space. Since this location is not randomized with ASLR,
2298 it can be used to assist security vulnerability exploitation.
2300 This setting can be changed at boot time via the kernel command
2301 line parameter vsyscall=[emulate|none].
2303 On a system with recent enough glibc (2.14 or newer) and no
2304 static binaries, you can say None without a performance penalty
2305 to improve security.
2307 If unsure, select "Emulate".
2309 config LEGACY_VSYSCALL_EMULATE
2312 The kernel traps and emulates calls into the fixed
2313 vsyscall address mapping. This makes the mapping
2314 non-executable, but it still contains known contents,
2315 which could be used in certain rare security vulnerability
2316 exploits. This configuration is recommended when userspace
2317 still uses the vsyscall area.
2319 config LEGACY_VSYSCALL_NONE
2322 There will be no vsyscall mapping at all. This will
2323 eliminate any risk of ASLR bypass due to the vsyscall
2324 fixed address mapping. Attempts to use the vsyscalls
2325 will be reported to dmesg, so that either old or
2326 malicious userspace programs can be identified.
2331 bool "Built-in kernel command line"
2333 Allow for specifying boot arguments to the kernel at
2334 build time. On some systems (e.g. embedded ones), it is
2335 necessary or convenient to provide some or all of the
2336 kernel boot arguments with the kernel itself (that is,
2337 to not rely on the boot loader to provide them.)
2339 To compile command line arguments into the kernel,
2340 set this option to 'Y', then fill in the
2341 boot arguments in CONFIG_CMDLINE.
2343 Systems with fully functional boot loaders (i.e. non-embedded)
2344 should leave this option set to 'N'.
2347 string "Built-in kernel command string"
2348 depends on CMDLINE_BOOL
2351 Enter arguments here that should be compiled into the kernel
2352 image and used at boot time. If the boot loader provides a
2353 command line at boot time, it is appended to this string to
2354 form the full kernel command line, when the system boots.
2356 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2357 change this behavior.
2359 In most cases, the command line (whether built-in or provided
2360 by the boot loader) should specify the device for the root
2363 config CMDLINE_OVERRIDE
2364 bool "Built-in command line overrides boot loader arguments"
2365 depends on CMDLINE_BOOL
2367 Set this option to 'Y' to have the kernel ignore the boot loader
2368 command line, and use ONLY the built-in command line.
2370 This is used to work around broken boot loaders. This should
2371 be set to 'N' under normal conditions.
2373 config MODIFY_LDT_SYSCALL
2374 bool "Enable the LDT (local descriptor table)" if EXPERT
2377 Linux can allow user programs to install a per-process x86
2378 Local Descriptor Table (LDT) using the modify_ldt(2) system
2379 call. This is required to run 16-bit or segmented code such as
2380 DOSEMU or some Wine programs. It is also used by some very old
2381 threading libraries.
2383 Enabling this feature adds a small amount of overhead to
2384 context switches and increases the low-level kernel attack
2385 surface. Disabling it removes the modify_ldt(2) system call.
2387 Saying 'N' here may make sense for embedded or server kernels.
2389 source "kernel/livepatch/Kconfig"
2393 config ARCH_HAS_ADD_PAGES
2395 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2397 config ARCH_ENABLE_MEMORY_HOTPLUG
2399 depends on X86_64 || (X86_32 && HIGHMEM)
2401 config ARCH_ENABLE_MEMORY_HOTREMOVE
2403 depends on MEMORY_HOTPLUG
2405 config USE_PERCPU_NUMA_NODE_ID
2409 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2411 depends on X86_64 || X86_PAE
2413 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2415 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2417 config ARCH_ENABLE_THP_MIGRATION
2419 depends on X86_64 && TRANSPARENT_HUGEPAGE
2421 menu "Power management and ACPI options"
2423 config ARCH_HIBERNATION_HEADER
2425 depends on HIBERNATION
2427 source "kernel/power/Kconfig"
2429 source "drivers/acpi/Kconfig"
2431 source "drivers/sfi/Kconfig"
2438 tristate "APM (Advanced Power Management) BIOS support"
2439 depends on X86_32 && PM_SLEEP
2441 APM is a BIOS specification for saving power using several different
2442 techniques. This is mostly useful for battery powered laptops with
2443 APM compliant BIOSes. If you say Y here, the system time will be
2444 reset after a RESUME operation, the /proc/apm device will provide
2445 battery status information, and user-space programs will receive
2446 notification of APM "events" (e.g. battery status change).
2448 If you select "Y" here, you can disable actual use of the APM
2449 BIOS by passing the "apm=off" option to the kernel at boot time.
2451 Note that the APM support is almost completely disabled for
2452 machines with more than one CPU.
2454 In order to use APM, you will need supporting software. For location
2455 and more information, read <file:Documentation/power/apm-acpi.txt>
2456 and the Battery Powered Linux mini-HOWTO, available from
2457 <http://www.tldp.org/docs.html#howto>.
2459 This driver does not spin down disk drives (see the hdparm(8)
2460 manpage ("man 8 hdparm") for that), and it doesn't turn off
2461 VESA-compliant "green" monitors.
2463 This driver does not support the TI 4000M TravelMate and the ACER
2464 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2465 desktop machines also don't have compliant BIOSes, and this driver
2466 may cause those machines to panic during the boot phase.
2468 Generally, if you don't have a battery in your machine, there isn't
2469 much point in using this driver and you should say N. If you get
2470 random kernel OOPSes or reboots that don't seem to be related to
2471 anything, try disabling/enabling this option (or disabling/enabling
2474 Some other things you should try when experiencing seemingly random,
2477 1) make sure that you have enough swap space and that it is
2479 2) pass the "no-hlt" option to the kernel
2480 3) switch on floating point emulation in the kernel and pass
2481 the "no387" option to the kernel
2482 4) pass the "floppy=nodma" option to the kernel
2483 5) pass the "mem=4M" option to the kernel (thereby disabling
2484 all but the first 4 MB of RAM)
2485 6) make sure that the CPU is not over clocked.
2486 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2487 8) disable the cache from your BIOS settings
2488 9) install a fan for the video card or exchange video RAM
2489 10) install a better fan for the CPU
2490 11) exchange RAM chips
2491 12) exchange the motherboard.
2493 To compile this driver as a module, choose M here: the
2494 module will be called apm.
2498 config APM_IGNORE_USER_SUSPEND
2499 bool "Ignore USER SUSPEND"
2501 This option will ignore USER SUSPEND requests. On machines with a
2502 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2503 series notebooks, it is necessary to say Y because of a BIOS bug.
2505 config APM_DO_ENABLE
2506 bool "Enable PM at boot time"
2508 Enable APM features at boot time. From page 36 of the APM BIOS
2509 specification: "When disabled, the APM BIOS does not automatically
2510 power manage devices, enter the Standby State, enter the Suspend
2511 State, or take power saving steps in response to CPU Idle calls."
2512 This driver will make CPU Idle calls when Linux is idle (unless this
2513 feature is turned off -- see "Do CPU IDLE calls", below). This
2514 should always save battery power, but more complicated APM features
2515 will be dependent on your BIOS implementation. You may need to turn
2516 this option off if your computer hangs at boot time when using APM
2517 support, or if it beeps continuously instead of suspending. Turn
2518 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2519 T400CDT. This is off by default since most machines do fine without
2524 bool "Make CPU Idle calls when idle"
2526 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2527 On some machines, this can activate improved power savings, such as
2528 a slowed CPU clock rate, when the machine is idle. These idle calls
2529 are made after the idle loop has run for some length of time (e.g.,
2530 333 mS). On some machines, this will cause a hang at boot time or
2531 whenever the CPU becomes idle. (On machines with more than one CPU,
2532 this option does nothing.)
2534 config APM_DISPLAY_BLANK
2535 bool "Enable console blanking using APM"
2537 Enable console blanking using the APM. Some laptops can use this to
2538 turn off the LCD backlight when the screen blanker of the Linux
2539 virtual console blanks the screen. Note that this is only used by
2540 the virtual console screen blanker, and won't turn off the backlight
2541 when using the X Window system. This also doesn't have anything to
2542 do with your VESA-compliant power-saving monitor. Further, this
2543 option doesn't work for all laptops -- it might not turn off your
2544 backlight at all, or it might print a lot of errors to the console,
2545 especially if you are using gpm.
2547 config APM_ALLOW_INTS
2548 bool "Allow interrupts during APM BIOS calls"
2550 Normally we disable external interrupts while we are making calls to
2551 the APM BIOS as a measure to lessen the effects of a badly behaving
2552 BIOS implementation. The BIOS should reenable interrupts if it
2553 needs to. Unfortunately, some BIOSes do not -- especially those in
2554 many of the newer IBM Thinkpads. If you experience hangs when you
2555 suspend, try setting this to Y. Otherwise, say N.
2559 source "drivers/cpufreq/Kconfig"
2561 source "drivers/cpuidle/Kconfig"
2563 source "drivers/idle/Kconfig"
2568 menu "Bus options (PCI etc.)"
2571 prompt "PCI access mode"
2572 depends on X86_32 && PCI
2575 On PCI systems, the BIOS can be used to detect the PCI devices and
2576 determine their configuration. However, some old PCI motherboards
2577 have BIOS bugs and may crash if this is done. Also, some embedded
2578 PCI-based systems don't have any BIOS at all. Linux can also try to
2579 detect the PCI hardware directly without using the BIOS.
2581 With this option, you can specify how Linux should detect the
2582 PCI devices. If you choose "BIOS", the BIOS will be used,
2583 if you choose "Direct", the BIOS won't be used, and if you
2584 choose "MMConfig", then PCI Express MMCONFIG will be used.
2585 If you choose "Any", the kernel will try MMCONFIG, then the
2586 direct access method and falls back to the BIOS if that doesn't
2587 work. If unsure, go with the default, which is "Any".
2592 config PCI_GOMMCONFIG
2609 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2611 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2614 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2617 bool "Support mmconfig PCI config space access" if X86_64
2619 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2620 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2624 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2628 depends on PCI && XEN
2631 config MMCONF_FAM10H
2633 depends on X86_64 && PCI_MMCONFIG && ACPI
2635 config PCI_CNB20LE_QUIRK
2636 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2639 Read the PCI windows out of the CNB20LE host bridge. This allows
2640 PCI hotplug to work on systems with the CNB20LE chipset which do
2643 There's no public spec for this chipset, and this functionality
2644 is known to be incomplete.
2646 You should say N unless you know you need this.
2649 bool "ISA bus support on modern systems" if EXPERT
2651 Expose ISA bus device drivers and options available for selection and
2652 configuration. Enable this option if your target machine has an ISA
2653 bus. ISA is an older system, displaced by PCI and newer bus
2654 architectures -- if your target machine is modern, it probably does
2655 not have an ISA bus.
2659 # x86_64 have no ISA slots, but can have ISA-style DMA.
2661 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2664 Enables ISA-style DMA support for devices requiring such controllers.
2672 Find out whether you have ISA slots on your motherboard. ISA is the
2673 name of a bus system, i.e. the way the CPU talks to the other stuff
2674 inside your box. Other bus systems are PCI, EISA, MicroChannel
2675 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2676 newer boards don't support it. If you have ISA, say Y, otherwise N.
2679 tristate "NatSemi SCx200 support"
2681 This provides basic support for National Semiconductor's
2682 (now AMD's) Geode processors. The driver probes for the
2683 PCI-IDs of several on-chip devices, so its a good dependency
2684 for other scx200_* drivers.
2686 If compiled as a module, the driver is named scx200.
2688 config SCx200HR_TIMER
2689 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2693 This driver provides a clocksource built upon the on-chip
2694 27MHz high-resolution timer. Its also a workaround for
2695 NSC Geode SC-1100's buggy TSC, which loses time when the
2696 processor goes idle (as is done by the scheduler). The
2697 other workaround is idle=poll boot option.
2700 bool "One Laptop Per Child support"
2707 Add support for detecting the unique features of the OLPC
2711 bool "OLPC XO-1 Power Management"
2712 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2714 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2717 bool "OLPC XO-1 Real Time Clock"
2718 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2720 Add support for the XO-1 real time clock, which can be used as a
2721 programmable wakeup source.
2724 bool "OLPC XO-1 SCI extras"
2725 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2729 Add support for SCI-based features of the OLPC XO-1 laptop:
2730 - EC-driven system wakeups
2734 - AC adapter status updates
2735 - Battery status updates
2737 config OLPC_XO15_SCI
2738 bool "OLPC XO-1.5 SCI extras"
2739 depends on OLPC && ACPI
2742 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2743 - EC-driven system wakeups
2744 - AC adapter status updates
2745 - Battery status updates
2748 bool "PCEngines ALIX System Support (LED setup)"
2751 This option enables system support for the PCEngines ALIX.
2752 At present this just sets up LEDs for GPIO control on
2753 ALIX2/3/6 boards. However, other system specific setup should
2756 Note: You must still enable the drivers for GPIO and LED support
2757 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2759 Note: You have to set alix.force=1 for boards with Award BIOS.
2762 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2765 This option enables system support for the Soekris Engineering net5501.
2768 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2772 This option enables system support for the Traverse Technologies GEOS.
2775 bool "Technologic Systems TS-5500 platform support"
2777 select CHECK_SIGNATURE
2781 This option enables system support for the Technologic Systems TS-5500.
2787 depends on CPU_SUP_AMD && PCI
2790 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2792 Firmwares often provide initial graphics framebuffers so the BIOS,
2793 bootloader or kernel can show basic video-output during boot for
2794 user-guidance and debugging. Historically, x86 used the VESA BIOS
2795 Extensions and EFI-framebuffers for this, which are mostly limited
2797 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2798 framebuffers so the new generic system-framebuffer drivers can be
2799 used on x86. If the framebuffer is not compatible with the generic
2800 modes, it is advertised as fallback platform framebuffer so legacy
2801 drivers like efifb, vesafb and uvesafb can pick it up.
2802 If this option is not selected, all system framebuffers are always
2803 marked as fallback platform framebuffers as usual.
2805 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2806 not be able to pick up generic system framebuffers if this option
2807 is selected. You are highly encouraged to enable simplefb as
2808 replacement if you select this option. simplefb can correctly deal
2809 with generic system framebuffers. But you should still keep vesafb
2810 and others enabled as fallback if a system framebuffer is
2811 incompatible with simplefb.
2818 menu "Binary Emulations"
2820 config IA32_EMULATION
2821 bool "IA32 Emulation"
2823 select ARCH_WANT_OLD_COMPAT_IPC
2825 select COMPAT_BINFMT_ELF
2826 select COMPAT_OLD_SIGACTION
2828 Include code to run legacy 32-bit programs under a
2829 64-bit kernel. You should likely turn this on, unless you're
2830 100% sure that you don't have any 32-bit programs left.
2833 tristate "IA32 a.out support"
2834 depends on IA32_EMULATION
2837 Support old a.out binaries in the 32bit emulation.
2840 bool "x32 ABI for 64-bit mode"
2843 Include code to run binaries for the x32 native 32-bit ABI
2844 for 64-bit processors. An x32 process gets access to the
2845 full 64-bit register file and wide data path while leaving
2846 pointers at 32 bits for smaller memory footprint.
2848 You will need a recent binutils (2.22 or later) with
2849 elf32_x86_64 support enabled to compile a kernel with this
2854 depends on IA32_EMULATION || X86_32
2856 select OLD_SIGSUSPEND3
2860 depends on IA32_EMULATION || X86_X32
2863 config COMPAT_FOR_U64_ALIGNMENT
2866 config SYSVIPC_COMPAT
2874 config HAVE_ATOMIC_IOMAP
2878 config X86_DEV_DMA_OPS
2880 depends on X86_64 || STA2X11
2882 config X86_DMA_REMAP
2886 config HAVE_GENERIC_GUP
2889 source "drivers/firmware/Kconfig"
2891 source "arch/x86/kvm/Kconfig"