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
48 select ARCH_32BIT_OFF_T if X86_32
49 select ARCH_CLOCKSOURCE_DATA
50 select ARCH_CLOCKSOURCE_INIT
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_STRICT_KERNEL_RWX
69 select ARCH_HAS_STRICT_MODULE_RWX
70 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
71 select ARCH_HAS_UBSAN_SANITIZE_ALL
72 select ARCH_HAS_ZONE_DEVICE if X86_64
73 select ARCH_HAVE_NMI_SAFE_CMPXCHG
74 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
75 select ARCH_MIGHT_HAVE_PC_PARPORT
76 select ARCH_MIGHT_HAVE_PC_SERIO
77 select ARCH_SUPPORTS_ACPI
78 select ARCH_SUPPORTS_ATOMIC_RMW
79 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
80 select ARCH_USE_BUILTIN_BSWAP
81 select ARCH_USE_QUEUED_RWLOCKS
82 select ARCH_USE_QUEUED_SPINLOCKS
83 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
84 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
85 select ARCH_WANTS_THP_SWAP if X86_64
86 select BUILDTIME_EXTABLE_SORT
88 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
89 select CLOCKSOURCE_WATCHDOG
90 select DCACHE_WORD_ACCESS
91 select EDAC_ATOMIC_SCRUB
93 select GENERIC_CLOCKEVENTS
94 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
95 select GENERIC_CLOCKEVENTS_MIN_ADJUST
96 select GENERIC_CMOS_UPDATE
97 select GENERIC_CPU_AUTOPROBE
98 select GENERIC_CPU_VULNERABILITIES
99 select GENERIC_EARLY_IOREMAP
100 select GENERIC_FIND_FIRST_BIT
102 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
103 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
104 select GENERIC_IRQ_MIGRATION if SMP
105 select GENERIC_IRQ_PROBE
106 select GENERIC_IRQ_RESERVATION_MODE
107 select GENERIC_IRQ_SHOW
108 select GENERIC_PENDING_IRQ if SMP
109 select GENERIC_SMP_IDLE_THREAD
110 select GENERIC_STRNCPY_FROM_USER
111 select GENERIC_STRNLEN_USER
112 select GENERIC_TIME_VSYSCALL
113 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
114 select HAVE_ACPI_APEI if ACPI
115 select HAVE_ACPI_APEI_NMI if ACPI
116 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
117 select HAVE_ARCH_AUDITSYSCALL
118 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
119 select HAVE_ARCH_JUMP_LABEL
120 select HAVE_ARCH_JUMP_LABEL_RELATIVE
121 select HAVE_ARCH_KASAN if X86_64
122 select HAVE_ARCH_KGDB
123 select HAVE_ARCH_MMAP_RND_BITS if MMU
124 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
125 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
126 select HAVE_ARCH_PREL32_RELOCATIONS
127 select HAVE_ARCH_SECCOMP_FILTER
128 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
129 select HAVE_ARCH_STACKLEAK
130 select HAVE_ARCH_TRACEHOOK
131 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
132 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
133 select HAVE_ARCH_VMAP_STACK if X86_64
134 select HAVE_ARCH_WITHIN_STACK_FRAMES
135 select HAVE_CMPXCHG_DOUBLE
136 select HAVE_CMPXCHG_LOCAL
137 select HAVE_CONTEXT_TRACKING if X86_64
138 select HAVE_COPY_THREAD_TLS
139 select HAVE_C_RECORDMCOUNT
140 select HAVE_DEBUG_KMEMLEAK
141 select HAVE_DEBUG_STACKOVERFLOW
142 select HAVE_DMA_CONTIGUOUS
143 select HAVE_DYNAMIC_FTRACE
144 select HAVE_DYNAMIC_FTRACE_WITH_REGS
146 select HAVE_EFFICIENT_UNALIGNED_ACCESS
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
171 select HAVE_MEMBLOCK_NODE_MAP
172 select HAVE_MIXED_BREAKPOINTS_REGS
173 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
183 select HAVE_PERF_REGS
184 select HAVE_PERF_USER_STACK_DUMP
185 select HAVE_RCU_TABLE_FREE if PARAVIRT
186 select HAVE_RCU_TABLE_INVALIDATE if HAVE_RCU_TABLE_FREE
187 select HAVE_REGS_AND_STACK_ACCESS_API
188 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
189 select HAVE_FUNCTION_ARG_ACCESS_API
190 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
191 select HAVE_STACK_VALIDATION if X86_64
193 select HAVE_SYSCALL_TRACEPOINTS
194 select HAVE_UNSTABLE_SCHED_CLOCK
195 select HAVE_USER_RETURN_NOTIFIER
196 select HOTPLUG_SMT if SMP
197 select IRQ_FORCED_THREADING
198 select NEED_SG_DMA_LENGTH
199 select PCI_DOMAINS if PCI
200 select PCI_LOCKLESS_CONFIG if PCI
203 select RTC_MC146818_LIB
206 select SYSCTL_EXCEPTION_TRACE
207 select THREAD_INFO_IN_TASK
208 select USER_STACKTRACE_SUPPORT
210 select X86_FEATURE_NAMES if PROC_FS
212 config INSTRUCTION_DECODER
214 depends on KPROBES || PERF_EVENTS || UPROBES
218 default "elf32-i386" if X86_32
219 default "elf64-x86-64" if X86_64
221 config ARCH_DEFCONFIG
223 default "arch/x86/configs/i386_defconfig" if X86_32
224 default "arch/x86/configs/x86_64_defconfig" if X86_64
226 config LOCKDEP_SUPPORT
229 config STACKTRACE_SUPPORT
235 config ARCH_MMAP_RND_BITS_MIN
239 config ARCH_MMAP_RND_BITS_MAX
243 config ARCH_MMAP_RND_COMPAT_BITS_MIN
246 config ARCH_MMAP_RND_COMPAT_BITS_MAX
252 config GENERIC_ISA_DMA
254 depends on ISA_DMA_API
259 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
261 config GENERIC_BUG_RELATIVE_POINTERS
264 config GENERIC_HWEIGHT
267 config ARCH_MAY_HAVE_PC_FDC
269 depends on ISA_DMA_API
271 config RWSEM_XCHGADD_ALGORITHM
274 config GENERIC_CALIBRATE_DELAY
277 config ARCH_HAS_CPU_RELAX
280 config ARCH_HAS_CACHE_LINE_SIZE
283 config ARCH_HAS_FILTER_PGPROT
286 config HAVE_SETUP_PER_CPU_AREA
289 config NEED_PER_CPU_EMBED_FIRST_CHUNK
292 config NEED_PER_CPU_PAGE_FIRST_CHUNK
295 config ARCH_HIBERNATION_POSSIBLE
298 config ARCH_SUSPEND_POSSIBLE
301 config ARCH_WANT_HUGE_PMD_SHARE
304 config ARCH_WANT_GENERAL_HUGETLB
313 config ARCH_SUPPORTS_OPTIMIZED_INLINING
316 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
319 config KASAN_SHADOW_OFFSET
322 default 0xdffffc0000000000
324 config HAVE_INTEL_TXT
326 depends on INTEL_IOMMU && ACPI
330 depends on X86_32 && SMP
334 depends on X86_64 && SMP
336 config X86_32_LAZY_GS
338 depends on X86_32 && !STACKPROTECTOR
340 config ARCH_SUPPORTS_UPROBES
343 config FIX_EARLYCON_MEM
346 config DYNAMIC_PHYSICAL_MASK
349 config PGTABLE_LEVELS
351 default 5 if X86_5LEVEL
356 config CC_HAS_SANE_STACKPROTECTOR
358 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
359 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
361 We have to make sure stack protector is unconditionally disabled if
362 the compiler produces broken code.
364 menu "Processor type and features"
367 bool "DMA memory allocation support" if EXPERT
370 DMA memory allocation support allows devices with less than 32-bit
371 addressing to allocate within the first 16MB of address space.
372 Disable if no such devices will be used.
377 bool "Symmetric multi-processing support"
379 This enables support for systems with more than one CPU. If you have
380 a system with only one CPU, say N. If you have a system with more
383 If you say N here, the kernel will run on uni- and multiprocessor
384 machines, but will use only one CPU of a multiprocessor machine. If
385 you say Y here, the kernel will run on many, but not all,
386 uniprocessor machines. On a uniprocessor machine, the kernel
387 will run faster if you say N here.
389 Note that if you say Y here and choose architecture "586" or
390 "Pentium" under "Processor family", the kernel will not work on 486
391 architectures. Similarly, multiprocessor kernels for the "PPro"
392 architecture may not work on all Pentium based boards.
394 People using multiprocessor machines who say Y here should also say
395 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
396 Management" code will be disabled if you say Y here.
398 See also <file:Documentation/x86/i386/IO-APIC.txt>,
399 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
400 <http://www.tldp.org/docs.html#howto>.
402 If you don't know what to do here, say N.
404 config X86_FEATURE_NAMES
405 bool "Processor feature human-readable names" if EMBEDDED
408 This option compiles in a table of x86 feature bits and corresponding
409 names. This is required to support /proc/cpuinfo and a few kernel
410 messages. You can disable this to save space, at the expense of
411 making those few kernel messages show numeric feature bits instead.
416 bool "Support x2apic"
417 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
419 This enables x2apic support on CPUs that have this feature.
421 This allows 32-bit apic IDs (so it can support very large systems),
422 and accesses the local apic via MSRs not via mmio.
424 If you don't know what to do here, say N.
427 bool "Enable MPS table" if ACPI || SFI
429 depends on X86_LOCAL_APIC
431 For old smp systems that do not have proper acpi support. Newer systems
432 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
436 depends on X86_GOLDFISH
439 bool "Avoid speculative indirect branches in kernel"
441 select STACK_VALIDATION if HAVE_STACK_VALIDATION
443 Compile kernel with the retpoline compiler options to guard against
444 kernel-to-user data leaks by avoiding speculative indirect
445 branches. Requires a compiler with -mindirect-branch=thunk-extern
446 support for full protection. The kernel may run slower.
448 config X86_CPU_RESCTRL
449 bool "x86 CPU resource control support"
450 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
453 Enable x86 CPU resource control support.
455 Provide support for the allocation and monitoring of system resources
458 Intel calls this Intel Resource Director Technology
459 (Intel(R) RDT). More information about RDT can be found in the
460 Intel x86 Architecture Software Developer Manual.
462 AMD calls this AMD Platform Quality of Service (AMD QoS).
463 More information about AMD QoS can be found in the AMD64 Technology
464 Platform Quality of Service Extensions manual.
470 bool "Support for big SMP systems with more than 8 CPUs"
473 This option is needed for the systems that have more than 8 CPUs
475 config X86_EXTENDED_PLATFORM
476 bool "Support for extended (non-PC) x86 platforms"
479 If you disable this option then the kernel will only support
480 standard PC platforms. (which covers the vast majority of
483 If you enable this option then you'll be able to select support
484 for the following (non-PC) 32 bit x86 platforms:
485 Goldfish (Android emulator)
488 SGI 320/540 (Visual Workstation)
489 STA2X11-based (e.g. Northville)
490 Moorestown MID devices
492 If you have one of these systems, or if you want to build a
493 generic distribution kernel, say Y here - otherwise say N.
497 config X86_EXTENDED_PLATFORM
498 bool "Support for extended (non-PC) x86 platforms"
501 If you disable this option then the kernel will only support
502 standard PC platforms. (which covers the vast majority of
505 If you enable this option then you'll be able to select support
506 for the following (non-PC) 64 bit x86 platforms:
511 If you have one of these systems, or if you want to build a
512 generic distribution kernel, say Y here - otherwise say N.
514 # This is an alphabetically sorted list of 64 bit extended platforms
515 # Please maintain the alphabetic order if and when there are additions
517 bool "Numascale NumaChip"
519 depends on X86_EXTENDED_PLATFORM
522 depends on X86_X2APIC
523 depends on PCI_MMCONFIG
525 Adds support for Numascale NumaChip large-SMP systems. Needed to
526 enable more than ~168 cores.
527 If you don't have one of these, you should say N here.
531 select HYPERVISOR_GUEST
533 depends on X86_64 && PCI
534 depends on X86_EXTENDED_PLATFORM
537 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
538 supposed to run on these EM64T-based machines. Only choose this option
539 if you have one of these machines.
542 bool "SGI Ultraviolet"
544 depends on X86_EXTENDED_PLATFORM
547 depends on X86_X2APIC
550 This option is needed in order to support SGI Ultraviolet systems.
551 If you don't have one of these, you should say N here.
553 # Following is an alphabetically sorted list of 32 bit extended platforms
554 # Please maintain the alphabetic order if and when there are additions
557 bool "Goldfish (Virtual Platform)"
558 depends on X86_EXTENDED_PLATFORM
560 Enable support for the Goldfish virtual platform used primarily
561 for Android development. Unless you are building for the Android
562 Goldfish emulator say N here.
565 bool "CE4100 TV platform"
567 depends on PCI_GODIRECT
568 depends on X86_IO_APIC
570 depends on X86_EXTENDED_PLATFORM
571 select X86_REBOOTFIXUPS
573 select OF_EARLY_FLATTREE
575 Select for the Intel CE media processor (CE4100) SOC.
576 This option compiles in support for the CE4100 SOC for settop
577 boxes and media devices.
580 bool "Intel MID platform support"
581 depends on X86_EXTENDED_PLATFORM
582 depends on X86_PLATFORM_DEVICES
584 depends on X86_64 || (PCI_GOANY && X86_32)
585 depends on X86_IO_APIC
591 select MFD_INTEL_MSIC
593 Select to build a kernel capable of supporting Intel MID (Mobile
594 Internet Device) platform systems which do not have the PCI legacy
595 interfaces. If you are building for a PC class system say N here.
597 Intel MID platforms are based on an Intel processor and chipset which
598 consume less power than most of the x86 derivatives.
600 config X86_INTEL_QUARK
601 bool "Intel Quark platform support"
603 depends on X86_EXTENDED_PLATFORM
604 depends on X86_PLATFORM_DEVICES
608 depends on X86_IO_APIC
613 Select to include support for Quark X1000 SoC.
614 Say Y here if you have a Quark based system such as the Arduino
615 compatible Intel Galileo.
617 config X86_INTEL_LPSS
618 bool "Intel Low Power Subsystem Support"
619 depends on X86 && ACPI && PCI
624 Select to build support for Intel Low Power Subsystem such as
625 found on Intel Lynxpoint PCH. Selecting this option enables
626 things like clock tree (common clock framework) and pincontrol
627 which are needed by the LPSS peripheral drivers.
629 config X86_AMD_PLATFORM_DEVICE
630 bool "AMD ACPI2Platform devices support"
635 Select to interpret AMD specific ACPI device to platform device
636 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
637 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
638 implemented under PINCTRL subsystem.
641 tristate "Intel SoC IOSF Sideband support for SoC platforms"
644 This option enables sideband register access support for Intel SoC
645 platforms. On these platforms the IOSF sideband is used in lieu of
646 MSR's for some register accesses, mostly but not limited to thermal
647 and power. Drivers may query the availability of this device to
648 determine if they need the sideband in order to work on these
649 platforms. The sideband is available on the following SoC products.
650 This list is not meant to be exclusive.
655 You should say Y if you are running a kernel on one of these SoC's.
657 config IOSF_MBI_DEBUG
658 bool "Enable IOSF sideband access through debugfs"
659 depends on IOSF_MBI && DEBUG_FS
661 Select this option to expose the IOSF sideband access registers (MCR,
662 MDR, MCRX) through debugfs to write and read register information from
663 different units on the SoC. This is most useful for obtaining device
664 state information for debug and analysis. As this is a general access
665 mechanism, users of this option would have specific knowledge of the
666 device they want to access.
668 If you don't require the option or are in doubt, say N.
671 bool "RDC R-321x SoC"
673 depends on X86_EXTENDED_PLATFORM
675 select X86_REBOOTFIXUPS
677 This option is needed for RDC R-321x system-on-chip, also known
679 If you don't have one of these chips, you should say N here.
681 config X86_32_NON_STANDARD
682 bool "Support non-standard 32-bit SMP architectures"
683 depends on X86_32 && SMP
684 depends on X86_EXTENDED_PLATFORM
686 This option compiles in the bigsmp and STA2X11 default
687 subarchitectures. It is intended for a generic binary
688 kernel. If you select them all, kernel will probe it one by
689 one and will fallback to default.
691 # Alphabetically sorted list of Non standard 32 bit platforms
693 config X86_SUPPORTS_MEMORY_FAILURE
695 # MCE code calls memory_failure():
697 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
698 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
699 depends on X86_64 || !SPARSEMEM
700 select ARCH_SUPPORTS_MEMORY_FAILURE
703 bool "STA2X11 Companion Chip Support"
704 depends on X86_32_NON_STANDARD && PCI
705 select ARCH_HAS_PHYS_TO_DMA
706 select X86_DEV_DMA_OPS
712 This adds support for boards based on the STA2X11 IO-Hub,
713 a.k.a. "ConneXt". The chip is used in place of the standard
714 PC chipset, so all "standard" peripherals are missing. If this
715 option is selected the kernel will still be able to boot on
716 standard PC machines.
719 tristate "Eurobraille/Iris poweroff module"
722 The Iris machines from EuroBraille do not have APM or ACPI support
723 to shut themselves down properly. A special I/O sequence is
724 needed to do so, which is what this module does at
727 This is only for Iris machines from EuroBraille.
731 config SCHED_OMIT_FRAME_POINTER
733 prompt "Single-depth WCHAN output"
736 Calculate simpler /proc/<PID>/wchan values. If this option
737 is disabled then wchan values will recurse back to the
738 caller function. This provides more accurate wchan values,
739 at the expense of slightly more scheduling overhead.
741 If in doubt, say "Y".
743 menuconfig HYPERVISOR_GUEST
744 bool "Linux guest support"
746 Say Y here to enable options for running Linux under various hyper-
747 visors. This option enables basic hypervisor detection and platform
750 If you say N, all options in this submenu will be skipped and
751 disabled, and Linux guest support won't be built in.
756 bool "Enable paravirtualization code"
758 This changes the kernel so it can modify itself when it is run
759 under a hypervisor, potentially improving performance significantly
760 over full virtualization. However, when run without a hypervisor
761 the kernel is theoretically slower and slightly larger.
766 config PARAVIRT_DEBUG
767 bool "paravirt-ops debugging"
768 depends on PARAVIRT && DEBUG_KERNEL
770 Enable to debug paravirt_ops internals. Specifically, BUG if
771 a paravirt_op is missing when it is called.
773 config PARAVIRT_SPINLOCKS
774 bool "Paravirtualization layer for spinlocks"
775 depends on PARAVIRT && SMP
777 Paravirtualized spinlocks allow a pvops backend to replace the
778 spinlock implementation with something virtualization-friendly
779 (for example, block the virtual CPU rather than spinning).
781 It has a minimal impact on native kernels and gives a nice performance
782 benefit on paravirtualized KVM / Xen kernels.
784 If you are unsure how to answer this question, answer Y.
786 config QUEUED_LOCK_STAT
787 bool "Paravirt queued spinlock statistics"
788 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
790 Enable the collection of statistical data on the slowpath
791 behavior of paravirtualized queued spinlocks and report
794 source "arch/x86/xen/Kconfig"
797 bool "KVM Guest support (including kvmclock)"
799 select PARAVIRT_CLOCK
802 This option enables various optimizations for running under the KVM
803 hypervisor. It includes a paravirtualized clock, so that instead
804 of relying on a PIT (or probably other) emulation by the
805 underlying device model, the host provides the guest with
806 timing infrastructure such as time of day, and system time
809 bool "Support for running PVH guests"
811 This option enables the PVH entry point for guest virtual machines
812 as specified in the x86/HVM direct boot ABI.
815 bool "Enable debug information for KVM Guests in debugfs"
816 depends on KVM_GUEST && DEBUG_FS
818 This option enables collection of various statistics for KVM guest.
819 Statistics are displayed in debugfs filesystem. Enabling this option
820 may incur significant overhead.
822 config PARAVIRT_TIME_ACCOUNTING
823 bool "Paravirtual steal time accounting"
826 Select this option to enable fine granularity task steal time
827 accounting. Time spent executing other tasks in parallel with
828 the current vCPU is discounted from the vCPU power. To account for
829 that, there can be a small performance impact.
831 If in doubt, say N here.
833 config PARAVIRT_CLOCK
836 config JAILHOUSE_GUEST
837 bool "Jailhouse non-root cell support"
838 depends on X86_64 && PCI
841 This option allows to run Linux as guest in a Jailhouse non-root
842 cell. You can leave this option disabled if you only want to start
843 Jailhouse and run Linux afterwards in the root cell.
845 endif #HYPERVISOR_GUEST
847 source "arch/x86/Kconfig.cpu"
851 prompt "HPET Timer Support" if X86_32
853 Use the IA-PC HPET (High Precision Event Timer) to manage
854 time in preference to the PIT and RTC, if a HPET is
856 HPET is the next generation timer replacing legacy 8254s.
857 The HPET provides a stable time base on SMP
858 systems, unlike the TSC, but it is more expensive to access,
859 as it is off-chip. The interface used is documented
860 in the HPET spec, revision 1.
862 You can safely choose Y here. However, HPET will only be
863 activated if the platform and the BIOS support this feature.
864 Otherwise the 8254 will be used for timing services.
866 Choose N to continue using the legacy 8254 timer.
868 config HPET_EMULATE_RTC
870 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
873 def_bool y if X86_INTEL_MID
874 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
876 depends on X86_INTEL_MID && SFI
878 APB timer is the replacement for 8254, HPET on X86 MID platforms.
879 The APBT provides a stable time base on SMP
880 systems, unlike the TSC, but it is more expensive to access,
881 as it is off-chip. APB timers are always running regardless of CPU
882 C states, they are used as per CPU clockevent device when possible.
884 # Mark as expert because too many people got it wrong.
885 # The code disables itself when not needed.
888 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
889 bool "Enable DMI scanning" if EXPERT
891 Enabled scanning of DMI to identify machine quirks. Say Y
892 here unless you have verified that your setup is not
893 affected by entries in the DMI blacklist. Required by PNP
897 bool "Old AMD GART IOMMU support"
900 depends on X86_64 && PCI && AMD_NB
902 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
903 GART based hardware IOMMUs.
905 The GART supports full DMA access for devices with 32-bit access
906 limitations, on systems with more than 3 GB. This is usually needed
907 for USB, sound, many IDE/SATA chipsets and some other devices.
909 Newer systems typically have a modern AMD IOMMU, supported via
910 the CONFIG_AMD_IOMMU=y config option.
912 In normal configurations this driver is only active when needed:
913 there's more than 3 GB of memory and the system contains a
914 32-bit limited device.
919 bool "IBM Calgary IOMMU support"
922 depends on X86_64 && PCI
924 Support for hardware IOMMUs in IBM's xSeries x366 and x460
925 systems. Needed to run systems with more than 3GB of memory
926 properly with 32-bit PCI devices that do not support DAC
927 (Double Address Cycle). Calgary also supports bus level
928 isolation, where all DMAs pass through the IOMMU. This
929 prevents them from going anywhere except their intended
930 destination. This catches hard-to-find kernel bugs and
931 mis-behaving drivers and devices that do not use the DMA-API
932 properly to set up their DMA buffers. The IOMMU can be
933 turned off at boot time with the iommu=off parameter.
934 Normally the kernel will make the right choice by itself.
937 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
939 prompt "Should Calgary be enabled by default?"
940 depends on CALGARY_IOMMU
942 Should Calgary be enabled by default? if you choose 'y', Calgary
943 will be used (if it exists). If you choose 'n', Calgary will not be
944 used even if it exists. If you choose 'n' and would like to use
945 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
949 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
950 depends on X86_64 && SMP && DEBUG_KERNEL
951 select CPUMASK_OFFSTACK
953 Enable maximum number of CPUS and NUMA Nodes for this architecture.
957 # The maximum number of CPUs supported:
959 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
960 # and which can be configured interactively in the
961 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
963 # The ranges are different on 32-bit and 64-bit kernels, depending on
964 # hardware capabilities and scalability features of the kernel.
966 # ( If MAXSMP is enabled we just use the highest possible value and disable
967 # interactive configuration. )
970 config NR_CPUS_RANGE_BEGIN
972 default NR_CPUS_RANGE_END if MAXSMP
976 config NR_CPUS_RANGE_END
979 default 64 if SMP && X86_BIGSMP
980 default 8 if SMP && !X86_BIGSMP
983 config NR_CPUS_RANGE_END
986 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
987 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
990 config NR_CPUS_DEFAULT
993 default 32 if X86_BIGSMP
997 config NR_CPUS_DEFAULT
1000 default 8192 if MAXSMP
1005 int "Maximum number of CPUs" if SMP && !MAXSMP
1006 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1007 default NR_CPUS_DEFAULT
1009 This allows you to specify the maximum number of CPUs which this
1010 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1011 supported value is 8192, otherwise the maximum value is 512. The
1012 minimum value which makes sense is 2.
1014 This is purely to save memory: each supported CPU adds about 8KB
1015 to the kernel image.
1022 prompt "Multi-core scheduler support"
1025 Multi-core scheduler support improves the CPU scheduler's decision
1026 making when dealing with multi-core CPU chips at a cost of slightly
1027 increased overhead in some places. If unsure say N here.
1029 config SCHED_MC_PRIO
1030 bool "CPU core priorities scheduler support"
1031 depends on SCHED_MC && CPU_SUP_INTEL
1032 select X86_INTEL_PSTATE
1036 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1037 core ordering determined at manufacturing time, which allows
1038 certain cores to reach higher turbo frequencies (when running
1039 single threaded workloads) than others.
1041 Enabling this kernel feature teaches the scheduler about
1042 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1043 scheduler's CPU selection logic accordingly, so that higher
1044 overall system performance can be achieved.
1046 This feature will have no effect on CPUs without this feature.
1048 If unsure say Y here.
1052 depends on !SMP && X86_LOCAL_APIC
1055 bool "Local APIC support on uniprocessors" if !PCI_MSI
1057 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1059 A local APIC (Advanced Programmable Interrupt Controller) is an
1060 integrated interrupt controller in the CPU. If you have a single-CPU
1061 system which has a processor with a local APIC, you can say Y here to
1062 enable and use it. If you say Y here even though your machine doesn't
1063 have a local APIC, then the kernel will still run with no slowdown at
1064 all. The local APIC supports CPU-generated self-interrupts (timer,
1065 performance counters), and the NMI watchdog which detects hard
1068 config X86_UP_IOAPIC
1069 bool "IO-APIC support on uniprocessors"
1070 depends on X86_UP_APIC
1072 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1073 SMP-capable replacement for PC-style interrupt controllers. Most
1074 SMP systems and many recent uniprocessor systems have one.
1076 If you have a single-CPU system with an IO-APIC, you can say Y here
1077 to use it. If you say Y here even though your machine doesn't have
1078 an IO-APIC, then the kernel will still run with no slowdown at all.
1080 config X86_LOCAL_APIC
1082 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1083 select IRQ_DOMAIN_HIERARCHY
1084 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1088 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1090 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1091 bool "Reroute for broken boot IRQs"
1092 depends on X86_IO_APIC
1094 This option enables a workaround that fixes a source of
1095 spurious interrupts. This is recommended when threaded
1096 interrupt handling is used on systems where the generation of
1097 superfluous "boot interrupts" cannot be disabled.
1099 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1100 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1101 kernel does during interrupt handling). On chipsets where this
1102 boot IRQ generation cannot be disabled, this workaround keeps
1103 the original IRQ line masked so that only the equivalent "boot
1104 IRQ" is delivered to the CPUs. The workaround also tells the
1105 kernel to set up the IRQ handler on the boot IRQ line. In this
1106 way only one interrupt is delivered to the kernel. Otherwise
1107 the spurious second interrupt may cause the kernel to bring
1108 down (vital) interrupt lines.
1110 Only affects "broken" chipsets. Interrupt sharing may be
1111 increased on these systems.
1114 bool "Machine Check / overheating reporting"
1115 select GENERIC_ALLOCATOR
1118 Machine Check support allows the processor to notify the
1119 kernel if it detects a problem (e.g. overheating, data corruption).
1120 The action the kernel takes depends on the severity of the problem,
1121 ranging from warning messages to halting the machine.
1123 config X86_MCELOG_LEGACY
1124 bool "Support for deprecated /dev/mcelog character device"
1127 Enable support for /dev/mcelog which is needed by the old mcelog
1128 userspace logging daemon. Consider switching to the new generation
1131 config X86_MCE_INTEL
1133 prompt "Intel MCE features"
1134 depends on X86_MCE && X86_LOCAL_APIC
1136 Additional support for intel specific MCE features such as
1137 the thermal monitor.
1141 prompt "AMD MCE features"
1142 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1144 Additional support for AMD specific MCE features such as
1145 the DRAM Error Threshold.
1147 config X86_ANCIENT_MCE
1148 bool "Support for old Pentium 5 / WinChip machine checks"
1149 depends on X86_32 && X86_MCE
1151 Include support for machine check handling on old Pentium 5 or WinChip
1152 systems. These typically need to be enabled explicitly on the command
1155 config X86_MCE_THRESHOLD
1156 depends on X86_MCE_AMD || X86_MCE_INTEL
1159 config X86_MCE_INJECT
1160 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1161 tristate "Machine check injector support"
1163 Provide support for injecting machine checks for testing purposes.
1164 If you don't know what a machine check is and you don't do kernel
1165 QA it is safe to say n.
1167 config X86_THERMAL_VECTOR
1169 depends on X86_MCE_INTEL
1171 source "arch/x86/events/Kconfig"
1173 config X86_LEGACY_VM86
1174 bool "Legacy VM86 support"
1177 This option allows user programs to put the CPU into V8086
1178 mode, which is an 80286-era approximation of 16-bit real mode.
1180 Some very old versions of X and/or vbetool require this option
1181 for user mode setting. Similarly, DOSEMU will use it if
1182 available to accelerate real mode DOS programs. However, any
1183 recent version of DOSEMU, X, or vbetool should be fully
1184 functional even without kernel VM86 support, as they will all
1185 fall back to software emulation. Nevertheless, if you are using
1186 a 16-bit DOS program where 16-bit performance matters, vm86
1187 mode might be faster than emulation and you might want to
1190 Note that any app that works on a 64-bit kernel is unlikely to
1191 need this option, as 64-bit kernels don't, and can't, support
1192 V8086 mode. This option is also unrelated to 16-bit protected
1193 mode and is not needed to run most 16-bit programs under Wine.
1195 Enabling this option increases the complexity of the kernel
1196 and slows down exception handling a tiny bit.
1198 If unsure, say N here.
1202 default X86_LEGACY_VM86
1205 bool "Enable support for 16-bit segments" if EXPERT
1207 depends on MODIFY_LDT_SYSCALL
1209 This option is required by programs like Wine to run 16-bit
1210 protected mode legacy code on x86 processors. Disabling
1211 this option saves about 300 bytes on i386, or around 6K text
1212 plus 16K runtime memory on x86-64,
1216 depends on X86_16BIT && X86_32
1220 depends on X86_16BIT && X86_64
1222 config X86_VSYSCALL_EMULATION
1223 bool "Enable vsyscall emulation" if EXPERT
1227 This enables emulation of the legacy vsyscall page. Disabling
1228 it is roughly equivalent to booting with vsyscall=none, except
1229 that it will also disable the helpful warning if a program
1230 tries to use a vsyscall. With this option set to N, offending
1231 programs will just segfault, citing addresses of the form
1234 This option is required by many programs built before 2013, and
1235 care should be used even with newer programs if set to N.
1237 Disabling this option saves about 7K of kernel size and
1238 possibly 4K of additional runtime pagetable memory.
1241 tristate "Toshiba Laptop support"
1244 This adds a driver to safely access the System Management Mode of
1245 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1246 not work on models with a Phoenix BIOS. The System Management Mode
1247 is used to set the BIOS and power saving options on Toshiba portables.
1249 For information on utilities to make use of this driver see the
1250 Toshiba Linux utilities web site at:
1251 <http://www.buzzard.org.uk/toshiba/>.
1253 Say Y if you intend to run this kernel on a Toshiba portable.
1257 tristate "Dell i8k legacy laptop support"
1259 select SENSORS_DELL_SMM
1261 This option enables legacy /proc/i8k userspace interface in hwmon
1262 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1263 temperature and allows controlling fan speeds of Dell laptops via
1264 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1265 it reports also power and hotkey status. For fan speed control is
1266 needed userspace package i8kutils.
1268 Say Y if you intend to run this kernel on old Dell laptops or want to
1269 use userspace package i8kutils.
1272 config X86_REBOOTFIXUPS
1273 bool "Enable X86 board specific fixups for reboot"
1276 This enables chipset and/or board specific fixups to be done
1277 in order to get reboot to work correctly. This is only needed on
1278 some combinations of hardware and BIOS. The symptom, for which
1279 this config is intended, is when reboot ends with a stalled/hung
1282 Currently, the only fixup is for the Geode machines using
1283 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1285 Say Y if you want to enable the fixup. Currently, it's safe to
1286 enable this option even if you don't need it.
1290 bool "CPU microcode loading support"
1292 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1295 If you say Y here, you will be able to update the microcode on
1296 Intel and AMD processors. The Intel support is for the IA32 family,
1297 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1298 AMD support is for families 0x10 and later. You will obviously need
1299 the actual microcode binary data itself which is not shipped with
1302 The preferred method to load microcode from a detached initrd is described
1303 in Documentation/x86/microcode.txt. For that you need to enable
1304 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1305 initrd for microcode blobs.
1307 In addition, you can build the microcode into the kernel. For that you
1308 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1311 config MICROCODE_INTEL
1312 bool "Intel microcode loading support"
1313 depends on MICROCODE
1317 This options enables microcode patch loading support for Intel
1320 For the current Intel microcode data package go to
1321 <https://downloadcenter.intel.com> and search for
1322 'Linux Processor Microcode Data File'.
1324 config MICROCODE_AMD
1325 bool "AMD microcode loading support"
1326 depends on MICROCODE
1329 If you select this option, microcode patch loading support for AMD
1330 processors will be enabled.
1332 config MICROCODE_OLD_INTERFACE
1334 depends on MICROCODE
1337 tristate "/dev/cpu/*/msr - Model-specific register support"
1339 This device gives privileged processes access to the x86
1340 Model-Specific Registers (MSRs). It is a character device with
1341 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1342 MSR accesses are directed to a specific CPU on multi-processor
1346 tristate "/dev/cpu/*/cpuid - CPU information support"
1348 This device gives processes access to the x86 CPUID instruction to
1349 be executed on a specific processor. It is a character device
1350 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1354 prompt "High Memory Support"
1361 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1362 However, the address space of 32-bit x86 processors is only 4
1363 Gigabytes large. That means that, if you have a large amount of
1364 physical memory, not all of it can be "permanently mapped" by the
1365 kernel. The physical memory that's not permanently mapped is called
1368 If you are compiling a kernel which will never run on a machine with
1369 more than 1 Gigabyte total physical RAM, answer "off" here (default
1370 choice and suitable for most users). This will result in a "3GB/1GB"
1371 split: 3GB are mapped so that each process sees a 3GB virtual memory
1372 space and the remaining part of the 4GB virtual memory space is used
1373 by the kernel to permanently map as much physical memory as
1376 If the machine has between 1 and 4 Gigabytes physical RAM, then
1379 If more than 4 Gigabytes is used then answer "64GB" here. This
1380 selection turns Intel PAE (Physical Address Extension) mode on.
1381 PAE implements 3-level paging on IA32 processors. PAE is fully
1382 supported by Linux, PAE mode is implemented on all recent Intel
1383 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1384 then the kernel will not boot on CPUs that don't support PAE!
1386 The actual amount of total physical memory will either be
1387 auto detected or can be forced by using a kernel command line option
1388 such as "mem=256M". (Try "man bootparam" or see the documentation of
1389 your boot loader (lilo or loadlin) about how to pass options to the
1390 kernel at boot time.)
1392 If unsure, say "off".
1397 Select this if you have a 32-bit processor and between 1 and 4
1398 gigabytes of physical RAM.
1402 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1405 Select this if you have a 32-bit processor and more than 4
1406 gigabytes of physical RAM.
1411 prompt "Memory split" if EXPERT
1415 Select the desired split between kernel and user memory.
1417 If the address range available to the kernel is less than the
1418 physical memory installed, the remaining memory will be available
1419 as "high memory". Accessing high memory is a little more costly
1420 than low memory, as it needs to be mapped into the kernel first.
1421 Note that increasing the kernel address space limits the range
1422 available to user programs, making the address space there
1423 tighter. Selecting anything other than the default 3G/1G split
1424 will also likely make your kernel incompatible with binary-only
1427 If you are not absolutely sure what you are doing, leave this
1431 bool "3G/1G user/kernel split"
1432 config VMSPLIT_3G_OPT
1434 bool "3G/1G user/kernel split (for full 1G low memory)"
1436 bool "2G/2G user/kernel split"
1437 config VMSPLIT_2G_OPT
1439 bool "2G/2G user/kernel split (for full 2G low memory)"
1441 bool "1G/3G user/kernel split"
1446 default 0xB0000000 if VMSPLIT_3G_OPT
1447 default 0x80000000 if VMSPLIT_2G
1448 default 0x78000000 if VMSPLIT_2G_OPT
1449 default 0x40000000 if VMSPLIT_1G
1455 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1458 bool "PAE (Physical Address Extension) Support"
1459 depends on X86_32 && !HIGHMEM4G
1460 select PHYS_ADDR_T_64BIT
1463 PAE is required for NX support, and furthermore enables
1464 larger swapspace support for non-overcommit purposes. It
1465 has the cost of more pagetable lookup overhead, and also
1466 consumes more pagetable space per process.
1469 bool "Enable 5-level page tables support"
1470 select DYNAMIC_MEMORY_LAYOUT
1471 select SPARSEMEM_VMEMMAP
1474 5-level paging enables access to larger address space:
1475 upto 128 PiB of virtual address space and 4 PiB of
1476 physical address space.
1478 It will be supported by future Intel CPUs.
1480 A kernel with the option enabled can be booted on machines that
1481 support 4- or 5-level paging.
1483 See Documentation/x86/x86_64/5level-paging.txt for more
1488 config X86_DIRECT_GBPAGES
1490 depends on X86_64 && !DEBUG_PAGEALLOC
1492 Certain kernel features effectively disable kernel
1493 linear 1 GB mappings (even if the CPU otherwise
1494 supports them), so don't confuse the user by printing
1495 that we have them enabled.
1497 config X86_CPA_STATISTICS
1498 bool "Enable statistic for Change Page Attribute"
1501 Expose statistics about the Change Page Attribute mechanims, which
1502 helps to determine the effectivness of preserving large and huge
1503 page mappings when mapping protections are changed.
1505 config ARCH_HAS_MEM_ENCRYPT
1508 config AMD_MEM_ENCRYPT
1509 bool "AMD Secure Memory Encryption (SME) support"
1510 depends on X86_64 && CPU_SUP_AMD
1511 select DYNAMIC_PHYSICAL_MASK
1512 select ARCH_USE_MEMREMAP_PROT
1514 Say yes to enable support for the encryption of system memory.
1515 This requires an AMD processor that supports Secure Memory
1518 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1519 bool "Activate AMD Secure Memory Encryption (SME) by default"
1521 depends on AMD_MEM_ENCRYPT
1523 Say yes to have system memory encrypted by default if running on
1524 an AMD processor that supports Secure Memory Encryption (SME).
1526 If set to Y, then the encryption of system memory can be
1527 deactivated with the mem_encrypt=off command line option.
1529 If set to N, then the encryption of system memory can be
1530 activated with the mem_encrypt=on command line option.
1532 # Common NUMA Features
1534 bool "Numa Memory Allocation and Scheduler Support"
1536 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1537 default y if X86_BIGSMP
1539 Enable NUMA (Non Uniform Memory Access) support.
1541 The kernel will try to allocate memory used by a CPU on the
1542 local memory controller of the CPU and add some more
1543 NUMA awareness to the kernel.
1545 For 64-bit this is recommended if the system is Intel Core i7
1546 (or later), AMD Opteron, or EM64T NUMA.
1548 For 32-bit this is only needed if you boot a 32-bit
1549 kernel on a 64-bit NUMA platform.
1551 Otherwise, you should say N.
1555 prompt "Old style AMD Opteron NUMA detection"
1556 depends on X86_64 && NUMA && PCI
1558 Enable AMD NUMA node topology detection. You should say Y here if
1559 you have a multi processor AMD system. This uses an old method to
1560 read the NUMA configuration directly from the builtin Northbridge
1561 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1562 which also takes priority if both are compiled in.
1564 config X86_64_ACPI_NUMA
1566 prompt "ACPI NUMA detection"
1567 depends on X86_64 && NUMA && ACPI && PCI
1570 Enable ACPI SRAT based node topology detection.
1572 # Some NUMA nodes have memory ranges that span
1573 # other nodes. Even though a pfn is valid and
1574 # between a node's start and end pfns, it may not
1575 # reside on that node. See memmap_init_zone()
1577 config NODES_SPAN_OTHER_NODES
1579 depends on X86_64_ACPI_NUMA
1582 bool "NUMA emulation"
1585 Enable NUMA emulation. A flat machine will be split
1586 into virtual nodes when booted with "numa=fake=N", where N is the
1587 number of nodes. This is only useful for debugging.
1590 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1592 default "10" if MAXSMP
1593 default "6" if X86_64
1595 depends on NEED_MULTIPLE_NODES
1597 Specify the maximum number of NUMA Nodes available on the target
1598 system. Increases memory reserved to accommodate various tables.
1600 config ARCH_HAVE_MEMORY_PRESENT
1602 depends on X86_32 && DISCONTIGMEM
1604 config ARCH_FLATMEM_ENABLE
1606 depends on X86_32 && !NUMA
1608 config ARCH_DISCONTIGMEM_ENABLE
1610 depends on NUMA && X86_32
1612 config ARCH_DISCONTIGMEM_DEFAULT
1614 depends on NUMA && X86_32
1616 config ARCH_SPARSEMEM_ENABLE
1618 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1619 select SPARSEMEM_STATIC if X86_32
1620 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1622 config ARCH_SPARSEMEM_DEFAULT
1626 config ARCH_SELECT_MEMORY_MODEL
1628 depends on ARCH_SPARSEMEM_ENABLE
1630 config ARCH_MEMORY_PROBE
1631 bool "Enable sysfs memory/probe interface"
1632 depends on X86_64 && MEMORY_HOTPLUG
1634 This option enables a sysfs memory/probe interface for testing.
1635 See Documentation/memory-hotplug.txt for more information.
1636 If you are unsure how to answer this question, answer N.
1638 config ARCH_PROC_KCORE_TEXT
1640 depends on X86_64 && PROC_KCORE
1642 config ILLEGAL_POINTER_VALUE
1645 default 0xdead000000000000 if X86_64
1647 config X86_PMEM_LEGACY_DEVICE
1650 config X86_PMEM_LEGACY
1651 tristate "Support non-standard NVDIMMs and ADR protected memory"
1652 depends on PHYS_ADDR_T_64BIT
1654 select X86_PMEM_LEGACY_DEVICE
1657 Treat memory marked using the non-standard e820 type of 12 as used
1658 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1659 The kernel will offer these regions to the 'pmem' driver so
1660 they can be used for persistent storage.
1665 bool "Allocate 3rd-level pagetables from highmem"
1668 The VM uses one page table entry for each page of physical memory.
1669 For systems with a lot of RAM, this can be wasteful of precious
1670 low memory. Setting this option will put user-space page table
1671 entries in high memory.
1673 config X86_CHECK_BIOS_CORRUPTION
1674 bool "Check for low memory corruption"
1676 Periodically check for memory corruption in low memory, which
1677 is suspected to be caused by BIOS. Even when enabled in the
1678 configuration, it is disabled at runtime. Enable it by
1679 setting "memory_corruption_check=1" on the kernel command
1680 line. By default it scans the low 64k of memory every 60
1681 seconds; see the memory_corruption_check_size and
1682 memory_corruption_check_period parameters in
1683 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1685 When enabled with the default parameters, this option has
1686 almost no overhead, as it reserves a relatively small amount
1687 of memory and scans it infrequently. It both detects corruption
1688 and prevents it from affecting the running system.
1690 It is, however, intended as a diagnostic tool; if repeatable
1691 BIOS-originated corruption always affects the same memory,
1692 you can use memmap= to prevent the kernel from using that
1695 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1696 bool "Set the default setting of memory_corruption_check"
1697 depends on X86_CHECK_BIOS_CORRUPTION
1700 Set whether the default state of memory_corruption_check is
1703 config X86_RESERVE_LOW
1704 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1708 Specify the amount of low memory to reserve for the BIOS.
1710 The first page contains BIOS data structures that the kernel
1711 must not use, so that page must always be reserved.
1713 By default we reserve the first 64K of physical RAM, as a
1714 number of BIOSes are known to corrupt that memory range
1715 during events such as suspend/resume or monitor cable
1716 insertion, so it must not be used by the kernel.
1718 You can set this to 4 if you are absolutely sure that you
1719 trust the BIOS to get all its memory reservations and usages
1720 right. If you know your BIOS have problems beyond the
1721 default 64K area, you can set this to 640 to avoid using the
1722 entire low memory range.
1724 If you have doubts about the BIOS (e.g. suspend/resume does
1725 not work or there's kernel crashes after certain hardware
1726 hotplug events) then you might want to enable
1727 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1728 typical corruption patterns.
1730 Leave this to the default value of 64 if you are unsure.
1732 config MATH_EMULATION
1734 depends on MODIFY_LDT_SYSCALL
1735 prompt "Math emulation" if X86_32
1737 Linux can emulate a math coprocessor (used for floating point
1738 operations) if you don't have one. 486DX and Pentium processors have
1739 a math coprocessor built in, 486SX and 386 do not, unless you added
1740 a 487DX or 387, respectively. (The messages during boot time can
1741 give you some hints here ["man dmesg"].) Everyone needs either a
1742 coprocessor or this emulation.
1744 If you don't have a math coprocessor, you need to say Y here; if you
1745 say Y here even though you have a coprocessor, the coprocessor will
1746 be used nevertheless. (This behavior can be changed with the kernel
1747 command line option "no387", which comes handy if your coprocessor
1748 is broken. Try "man bootparam" or see the documentation of your boot
1749 loader (lilo or loadlin) about how to pass options to the kernel at
1750 boot time.) This means that it is a good idea to say Y here if you
1751 intend to use this kernel on different machines.
1753 More information about the internals of the Linux math coprocessor
1754 emulation can be found in <file:arch/x86/math-emu/README>.
1756 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1757 kernel, it won't hurt.
1761 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1763 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1764 the Memory Type Range Registers (MTRRs) may be used to control
1765 processor access to memory ranges. This is most useful if you have
1766 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1767 allows bus write transfers to be combined into a larger transfer
1768 before bursting over the PCI/AGP bus. This can increase performance
1769 of image write operations 2.5 times or more. Saying Y here creates a
1770 /proc/mtrr file which may be used to manipulate your processor's
1771 MTRRs. Typically the X server should use this.
1773 This code has a reasonably generic interface so that similar
1774 control registers on other processors can be easily supported
1777 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1778 Registers (ARRs) which provide a similar functionality to MTRRs. For
1779 these, the ARRs are used to emulate the MTRRs.
1780 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1781 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1782 write-combining. All of these processors are supported by this code
1783 and it makes sense to say Y here if you have one of them.
1785 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1786 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1787 can lead to all sorts of problems, so it's good to say Y here.
1789 You can safely say Y even if your machine doesn't have MTRRs, you'll
1790 just add about 9 KB to your kernel.
1792 See <file:Documentation/x86/mtrr.txt> for more information.
1794 config MTRR_SANITIZER
1796 prompt "MTRR cleanup support"
1799 Convert MTRR layout from continuous to discrete, so X drivers can
1800 add writeback entries.
1802 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1803 The largest mtrr entry size for a continuous block can be set with
1808 config MTRR_SANITIZER_ENABLE_DEFAULT
1809 int "MTRR cleanup enable value (0-1)"
1812 depends on MTRR_SANITIZER
1814 Enable mtrr cleanup default value
1816 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1817 int "MTRR cleanup spare reg num (0-7)"
1820 depends on MTRR_SANITIZER
1822 mtrr cleanup spare entries default, it can be changed via
1823 mtrr_spare_reg_nr=N on the kernel command line.
1827 prompt "x86 PAT support" if EXPERT
1830 Use PAT attributes to setup page level cache control.
1832 PATs are the modern equivalents of MTRRs and are much more
1833 flexible than MTRRs.
1835 Say N here if you see bootup problems (boot crash, boot hang,
1836 spontaneous reboots) or a non-working video driver.
1840 config ARCH_USES_PG_UNCACHED
1846 prompt "x86 architectural random number generator" if EXPERT
1848 Enable the x86 architectural RDRAND instruction
1849 (Intel Bull Mountain technology) to generate random numbers.
1850 If supported, this is a high bandwidth, cryptographically
1851 secure hardware random number generator.
1855 prompt "Supervisor Mode Access Prevention" if EXPERT
1857 Supervisor Mode Access Prevention (SMAP) is a security
1858 feature in newer Intel processors. There is a small
1859 performance cost if this enabled and turned on; there is
1860 also a small increase in the kernel size if this is enabled.
1864 config X86_INTEL_UMIP
1866 depends on CPU_SUP_INTEL
1867 prompt "Intel User Mode Instruction Prevention" if EXPERT
1869 The User Mode Instruction Prevention (UMIP) is a security
1870 feature in newer Intel processors. If enabled, a general
1871 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1872 or STR instructions are executed in user mode. These instructions
1873 unnecessarily expose information about the hardware state.
1875 The vast majority of applications do not use these instructions.
1876 For the very few that do, software emulation is provided in
1877 specific cases in protected and virtual-8086 modes. Emulated
1880 config X86_INTEL_MPX
1881 prompt "Intel MPX (Memory Protection Extensions)"
1883 # Note: only available in 64-bit mode due to VMA flags shortage
1884 depends on CPU_SUP_INTEL && X86_64
1885 select ARCH_USES_HIGH_VMA_FLAGS
1887 MPX provides hardware features that can be used in
1888 conjunction with compiler-instrumented code to check
1889 memory references. It is designed to detect buffer
1890 overflow or underflow bugs.
1892 This option enables running applications which are
1893 instrumented or otherwise use MPX. It does not use MPX
1894 itself inside the kernel or to protect the kernel
1895 against bad memory references.
1897 Enabling this option will make the kernel larger:
1898 ~8k of kernel text and 36 bytes of data on a 64-bit
1899 defconfig. It adds a long to the 'mm_struct' which
1900 will increase the kernel memory overhead of each
1901 process and adds some branches to paths used during
1902 exec() and munmap().
1904 For details, see Documentation/x86/intel_mpx.txt
1908 config X86_INTEL_MEMORY_PROTECTION_KEYS
1909 prompt "Intel Memory Protection Keys"
1911 # Note: only available in 64-bit mode
1912 depends on CPU_SUP_INTEL && X86_64
1913 select ARCH_USES_HIGH_VMA_FLAGS
1914 select ARCH_HAS_PKEYS
1916 Memory Protection Keys provides a mechanism for enforcing
1917 page-based protections, but without requiring modification of the
1918 page tables when an application changes protection domains.
1920 For details, see Documentation/x86/protection-keys.txt
1925 bool "EFI runtime service support"
1928 select EFI_RUNTIME_WRAPPERS
1930 This enables the kernel to use EFI runtime services that are
1931 available (such as the EFI variable services).
1933 This option is only useful on systems that have EFI firmware.
1934 In addition, you should use the latest ELILO loader available
1935 at <http://elilo.sourceforge.net> in order to take advantage
1936 of EFI runtime services. However, even with this option, the
1937 resultant kernel should continue to boot on existing non-EFI
1941 bool "EFI stub support"
1942 depends on EFI && !X86_USE_3DNOW
1945 This kernel feature allows a bzImage to be loaded directly
1946 by EFI firmware without the use of a bootloader.
1948 See Documentation/efi-stub.txt for more information.
1951 bool "EFI mixed-mode support"
1952 depends on EFI_STUB && X86_64
1954 Enabling this feature allows a 64-bit kernel to be booted
1955 on a 32-bit firmware, provided that your CPU supports 64-bit
1958 Note that it is not possible to boot a mixed-mode enabled
1959 kernel via the EFI boot stub - a bootloader that supports
1960 the EFI handover protocol must be used.
1966 prompt "Enable seccomp to safely compute untrusted bytecode"
1968 This kernel feature is useful for number crunching applications
1969 that may need to compute untrusted bytecode during their
1970 execution. By using pipes or other transports made available to
1971 the process as file descriptors supporting the read/write
1972 syscalls, it's possible to isolate those applications in
1973 their own address space using seccomp. Once seccomp is
1974 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1975 and the task is only allowed to execute a few safe syscalls
1976 defined by each seccomp mode.
1978 If unsure, say Y. Only embedded should say N here.
1980 source "kernel/Kconfig.hz"
1983 bool "kexec system call"
1986 kexec is a system call that implements the ability to shutdown your
1987 current kernel, and to start another kernel. It is like a reboot
1988 but it is independent of the system firmware. And like a reboot
1989 you can start any kernel with it, not just Linux.
1991 The name comes from the similarity to the exec system call.
1993 It is an ongoing process to be certain the hardware in a machine
1994 is properly shutdown, so do not be surprised if this code does not
1995 initially work for you. As of this writing the exact hardware
1996 interface is strongly in flux, so no good recommendation can be
2000 bool "kexec file based system call"
2005 depends on CRYPTO_SHA256=y
2007 This is new version of kexec system call. This system call is
2008 file based and takes file descriptors as system call argument
2009 for kernel and initramfs as opposed to list of segments as
2010 accepted by previous system call.
2012 config ARCH_HAS_KEXEC_PURGATORY
2015 config KEXEC_VERIFY_SIG
2016 bool "Verify kernel signature during kexec_file_load() syscall"
2017 depends on KEXEC_FILE
2019 This option makes kernel signature verification mandatory for
2020 the kexec_file_load() syscall.
2022 In addition to that option, you need to enable signature
2023 verification for the corresponding kernel image type being
2024 loaded in order for this to work.
2026 config KEXEC_BZIMAGE_VERIFY_SIG
2027 bool "Enable bzImage signature verification support"
2028 depends on KEXEC_VERIFY_SIG
2029 depends on SIGNED_PE_FILE_VERIFICATION
2030 select SYSTEM_TRUSTED_KEYRING
2032 Enable bzImage signature verification support.
2035 bool "kernel crash dumps"
2036 depends on X86_64 || (X86_32 && HIGHMEM)
2038 Generate crash dump after being started by kexec.
2039 This should be normally only set in special crash dump kernels
2040 which are loaded in the main kernel with kexec-tools into
2041 a specially reserved region and then later executed after
2042 a crash by kdump/kexec. The crash dump kernel must be compiled
2043 to a memory address not used by the main kernel or BIOS using
2044 PHYSICAL_START, or it must be built as a relocatable image
2045 (CONFIG_RELOCATABLE=y).
2046 For more details see Documentation/kdump/kdump.txt
2050 depends on KEXEC && HIBERNATION
2052 Jump between original kernel and kexeced kernel and invoke
2053 code in physical address mode via KEXEC
2055 config PHYSICAL_START
2056 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2059 This gives the physical address where the kernel is loaded.
2061 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2062 bzImage will decompress itself to above physical address and
2063 run from there. Otherwise, bzImage will run from the address where
2064 it has been loaded by the boot loader and will ignore above physical
2067 In normal kdump cases one does not have to set/change this option
2068 as now bzImage can be compiled as a completely relocatable image
2069 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2070 address. This option is mainly useful for the folks who don't want
2071 to use a bzImage for capturing the crash dump and want to use a
2072 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2073 to be specifically compiled to run from a specific memory area
2074 (normally a reserved region) and this option comes handy.
2076 So if you are using bzImage for capturing the crash dump,
2077 leave the value here unchanged to 0x1000000 and set
2078 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2079 for capturing the crash dump change this value to start of
2080 the reserved region. In other words, it can be set based on
2081 the "X" value as specified in the "crashkernel=YM@XM"
2082 command line boot parameter passed to the panic-ed
2083 kernel. Please take a look at Documentation/kdump/kdump.txt
2084 for more details about crash dumps.
2086 Usage of bzImage for capturing the crash dump is recommended as
2087 one does not have to build two kernels. Same kernel can be used
2088 as production kernel and capture kernel. Above option should have
2089 gone away after relocatable bzImage support is introduced. But it
2090 is present because there are users out there who continue to use
2091 vmlinux for dump capture. This option should go away down the
2094 Don't change this unless you know what you are doing.
2097 bool "Build a relocatable kernel"
2100 This builds a kernel image that retains relocation information
2101 so it can be loaded someplace besides the default 1MB.
2102 The relocations tend to make the kernel binary about 10% larger,
2103 but are discarded at runtime.
2105 One use is for the kexec on panic case where the recovery kernel
2106 must live at a different physical address than the primary
2109 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2110 it has been loaded at and the compile time physical address
2111 (CONFIG_PHYSICAL_START) is used as the minimum location.
2113 config RANDOMIZE_BASE
2114 bool "Randomize the address of the kernel image (KASLR)"
2115 depends on RELOCATABLE
2118 In support of Kernel Address Space Layout Randomization (KASLR),
2119 this randomizes the physical address at which the kernel image
2120 is decompressed and the virtual address where the kernel
2121 image is mapped, as a security feature that deters exploit
2122 attempts relying on knowledge of the location of kernel
2125 On 64-bit, the kernel physical and virtual addresses are
2126 randomized separately. The physical address will be anywhere
2127 between 16MB and the top of physical memory (up to 64TB). The
2128 virtual address will be randomized from 16MB up to 1GB (9 bits
2129 of entropy). Note that this also reduces the memory space
2130 available to kernel modules from 1.5GB to 1GB.
2132 On 32-bit, the kernel physical and virtual addresses are
2133 randomized together. They will be randomized from 16MB up to
2134 512MB (8 bits of entropy).
2136 Entropy is generated using the RDRAND instruction if it is
2137 supported. If RDTSC is supported, its value is mixed into
2138 the entropy pool as well. If neither RDRAND nor RDTSC are
2139 supported, then entropy is read from the i8254 timer. The
2140 usable entropy is limited by the kernel being built using
2141 2GB addressing, and that PHYSICAL_ALIGN must be at a
2142 minimum of 2MB. As a result, only 10 bits of entropy are
2143 theoretically possible, but the implementations are further
2144 limited due to memory layouts.
2148 # Relocation on x86 needs some additional build support
2149 config X86_NEED_RELOCS
2151 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2153 config PHYSICAL_ALIGN
2154 hex "Alignment value to which kernel should be aligned"
2156 range 0x2000 0x1000000 if X86_32
2157 range 0x200000 0x1000000 if X86_64
2159 This value puts the alignment restrictions on physical address
2160 where kernel is loaded and run from. Kernel is compiled for an
2161 address which meets above alignment restriction.
2163 If bootloader loads the kernel at a non-aligned address and
2164 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2165 address aligned to above value and run from there.
2167 If bootloader loads the kernel at a non-aligned address and
2168 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2169 load address and decompress itself to the address it has been
2170 compiled for and run from there. The address for which kernel is
2171 compiled already meets above alignment restrictions. Hence the
2172 end result is that kernel runs from a physical address meeting
2173 above alignment restrictions.
2175 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2176 this value must be a multiple of 0x200000.
2178 Don't change this unless you know what you are doing.
2180 config DYNAMIC_MEMORY_LAYOUT
2183 This option makes base addresses of vmalloc and vmemmap as well as
2184 __PAGE_OFFSET movable during boot.
2186 config RANDOMIZE_MEMORY
2187 bool "Randomize the kernel memory sections"
2189 depends on RANDOMIZE_BASE
2190 select DYNAMIC_MEMORY_LAYOUT
2191 default RANDOMIZE_BASE
2193 Randomizes the base virtual address of kernel memory sections
2194 (physical memory mapping, vmalloc & vmemmap). This security feature
2195 makes exploits relying on predictable memory locations less reliable.
2197 The order of allocations remains unchanged. Entropy is generated in
2198 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2199 configuration have in average 30,000 different possible virtual
2200 addresses for each memory section.
2204 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2205 hex "Physical memory mapping padding" if EXPERT
2206 depends on RANDOMIZE_MEMORY
2207 default "0xa" if MEMORY_HOTPLUG
2209 range 0x1 0x40 if MEMORY_HOTPLUG
2212 Define the padding in terabytes added to the existing physical
2213 memory size during kernel memory randomization. It is useful
2214 for memory hotplug support but reduces the entropy available for
2215 address randomization.
2217 If unsure, leave at the default value.
2220 bool "Support for hot-pluggable CPUs"
2223 Say Y here to allow turning CPUs off and on. CPUs can be
2224 controlled through /sys/devices/system/cpu.
2225 ( Note: power management support will enable this option
2226 automatically on SMP systems. )
2227 Say N if you want to disable CPU hotplug.
2229 config BOOTPARAM_HOTPLUG_CPU0
2230 bool "Set default setting of cpu0_hotpluggable"
2231 depends on HOTPLUG_CPU
2233 Set whether default state of cpu0_hotpluggable is on or off.
2235 Say Y here to enable CPU0 hotplug by default. If this switch
2236 is turned on, there is no need to give cpu0_hotplug kernel
2237 parameter and the CPU0 hotplug feature is enabled by default.
2239 Please note: there are two known CPU0 dependencies if you want
2240 to enable the CPU0 hotplug feature either by this switch or by
2241 cpu0_hotplug kernel parameter.
2243 First, resume from hibernate or suspend always starts from CPU0.
2244 So hibernate and suspend are prevented if CPU0 is offline.
2246 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2247 offline if any interrupt can not migrate out of CPU0. There may
2248 be other CPU0 dependencies.
2250 Please make sure the dependencies are under your control before
2251 you enable this feature.
2253 Say N if you don't want to enable CPU0 hotplug feature by default.
2254 You still can enable the CPU0 hotplug feature at boot by kernel
2255 parameter cpu0_hotplug.
2257 config DEBUG_HOTPLUG_CPU0
2259 prompt "Debug CPU0 hotplug"
2260 depends on HOTPLUG_CPU
2262 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2263 soon as possible and boots up userspace with CPU0 offlined. User
2264 can online CPU0 back after boot time.
2266 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2267 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2268 compilation or giving cpu0_hotplug kernel parameter at boot.
2274 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2275 depends on COMPAT_32
2277 Certain buggy versions of glibc will crash if they are
2278 presented with a 32-bit vDSO that is not mapped at the address
2279 indicated in its segment table.
2281 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2282 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2283 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2284 the only released version with the bug, but OpenSUSE 9
2285 contains a buggy "glibc 2.3.2".
2287 The symptom of the bug is that everything crashes on startup, saying:
2288 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2290 Saying Y here changes the default value of the vdso32 boot
2291 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2292 This works around the glibc bug but hurts performance.
2294 If unsure, say N: if you are compiling your own kernel, you
2295 are unlikely to be using a buggy version of glibc.
2298 prompt "vsyscall table for legacy applications"
2300 default LEGACY_VSYSCALL_EMULATE
2302 Legacy user code that does not know how to find the vDSO expects
2303 to be able to issue three syscalls by calling fixed addresses in
2304 kernel space. Since this location is not randomized with ASLR,
2305 it can be used to assist security vulnerability exploitation.
2307 This setting can be changed at boot time via the kernel command
2308 line parameter vsyscall=[emulate|none].
2310 On a system with recent enough glibc (2.14 or newer) and no
2311 static binaries, you can say None without a performance penalty
2312 to improve security.
2314 If unsure, select "Emulate".
2316 config LEGACY_VSYSCALL_EMULATE
2319 The kernel traps and emulates calls into the fixed
2320 vsyscall address mapping. This makes the mapping
2321 non-executable, but it still contains known contents,
2322 which could be used in certain rare security vulnerability
2323 exploits. This configuration is recommended when userspace
2324 still uses the vsyscall area.
2326 config LEGACY_VSYSCALL_NONE
2329 There will be no vsyscall mapping at all. This will
2330 eliminate any risk of ASLR bypass due to the vsyscall
2331 fixed address mapping. Attempts to use the vsyscalls
2332 will be reported to dmesg, so that either old or
2333 malicious userspace programs can be identified.
2338 bool "Built-in kernel command line"
2340 Allow for specifying boot arguments to the kernel at
2341 build time. On some systems (e.g. embedded ones), it is
2342 necessary or convenient to provide some or all of the
2343 kernel boot arguments with the kernel itself (that is,
2344 to not rely on the boot loader to provide them.)
2346 To compile command line arguments into the kernel,
2347 set this option to 'Y', then fill in the
2348 boot arguments in CONFIG_CMDLINE.
2350 Systems with fully functional boot loaders (i.e. non-embedded)
2351 should leave this option set to 'N'.
2354 string "Built-in kernel command string"
2355 depends on CMDLINE_BOOL
2358 Enter arguments here that should be compiled into the kernel
2359 image and used at boot time. If the boot loader provides a
2360 command line at boot time, it is appended to this string to
2361 form the full kernel command line, when the system boots.
2363 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2364 change this behavior.
2366 In most cases, the command line (whether built-in or provided
2367 by the boot loader) should specify the device for the root
2370 config CMDLINE_OVERRIDE
2371 bool "Built-in command line overrides boot loader arguments"
2372 depends on CMDLINE_BOOL
2374 Set this option to 'Y' to have the kernel ignore the boot loader
2375 command line, and use ONLY the built-in command line.
2377 This is used to work around broken boot loaders. This should
2378 be set to 'N' under normal conditions.
2380 config MODIFY_LDT_SYSCALL
2381 bool "Enable the LDT (local descriptor table)" if EXPERT
2384 Linux can allow user programs to install a per-process x86
2385 Local Descriptor Table (LDT) using the modify_ldt(2) system
2386 call. This is required to run 16-bit or segmented code such as
2387 DOSEMU or some Wine programs. It is also used by some very old
2388 threading libraries.
2390 Enabling this feature adds a small amount of overhead to
2391 context switches and increases the low-level kernel attack
2392 surface. Disabling it removes the modify_ldt(2) system call.
2394 Saying 'N' here may make sense for embedded or server kernels.
2396 source "kernel/livepatch/Kconfig"
2400 config ARCH_HAS_ADD_PAGES
2402 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2404 config ARCH_ENABLE_MEMORY_HOTPLUG
2406 depends on X86_64 || (X86_32 && HIGHMEM)
2408 config ARCH_ENABLE_MEMORY_HOTREMOVE
2410 depends on MEMORY_HOTPLUG
2412 config USE_PERCPU_NUMA_NODE_ID
2416 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2418 depends on X86_64 || X86_PAE
2420 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2422 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2424 config ARCH_ENABLE_THP_MIGRATION
2426 depends on X86_64 && TRANSPARENT_HUGEPAGE
2428 menu "Power management and ACPI options"
2430 config ARCH_HIBERNATION_HEADER
2432 depends on HIBERNATION
2434 source "kernel/power/Kconfig"
2436 source "drivers/acpi/Kconfig"
2438 source "drivers/sfi/Kconfig"
2445 tristate "APM (Advanced Power Management) BIOS support"
2446 depends on X86_32 && PM_SLEEP
2448 APM is a BIOS specification for saving power using several different
2449 techniques. This is mostly useful for battery powered laptops with
2450 APM compliant BIOSes. If you say Y here, the system time will be
2451 reset after a RESUME operation, the /proc/apm device will provide
2452 battery status information, and user-space programs will receive
2453 notification of APM "events" (e.g. battery status change).
2455 If you select "Y" here, you can disable actual use of the APM
2456 BIOS by passing the "apm=off" option to the kernel at boot time.
2458 Note that the APM support is almost completely disabled for
2459 machines with more than one CPU.
2461 In order to use APM, you will need supporting software. For location
2462 and more information, read <file:Documentation/power/apm-acpi.txt>
2463 and the Battery Powered Linux mini-HOWTO, available from
2464 <http://www.tldp.org/docs.html#howto>.
2466 This driver does not spin down disk drives (see the hdparm(8)
2467 manpage ("man 8 hdparm") for that), and it doesn't turn off
2468 VESA-compliant "green" monitors.
2470 This driver does not support the TI 4000M TravelMate and the ACER
2471 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2472 desktop machines also don't have compliant BIOSes, and this driver
2473 may cause those machines to panic during the boot phase.
2475 Generally, if you don't have a battery in your machine, there isn't
2476 much point in using this driver and you should say N. If you get
2477 random kernel OOPSes or reboots that don't seem to be related to
2478 anything, try disabling/enabling this option (or disabling/enabling
2481 Some other things you should try when experiencing seemingly random,
2484 1) make sure that you have enough swap space and that it is
2486 2) pass the "no-hlt" option to the kernel
2487 3) switch on floating point emulation in the kernel and pass
2488 the "no387" option to the kernel
2489 4) pass the "floppy=nodma" option to the kernel
2490 5) pass the "mem=4M" option to the kernel (thereby disabling
2491 all but the first 4 MB of RAM)
2492 6) make sure that the CPU is not over clocked.
2493 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2494 8) disable the cache from your BIOS settings
2495 9) install a fan for the video card or exchange video RAM
2496 10) install a better fan for the CPU
2497 11) exchange RAM chips
2498 12) exchange the motherboard.
2500 To compile this driver as a module, choose M here: the
2501 module will be called apm.
2505 config APM_IGNORE_USER_SUSPEND
2506 bool "Ignore USER SUSPEND"
2508 This option will ignore USER SUSPEND requests. On machines with a
2509 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2510 series notebooks, it is necessary to say Y because of a BIOS bug.
2512 config APM_DO_ENABLE
2513 bool "Enable PM at boot time"
2515 Enable APM features at boot time. From page 36 of the APM BIOS
2516 specification: "When disabled, the APM BIOS does not automatically
2517 power manage devices, enter the Standby State, enter the Suspend
2518 State, or take power saving steps in response to CPU Idle calls."
2519 This driver will make CPU Idle calls when Linux is idle (unless this
2520 feature is turned off -- see "Do CPU IDLE calls", below). This
2521 should always save battery power, but more complicated APM features
2522 will be dependent on your BIOS implementation. You may need to turn
2523 this option off if your computer hangs at boot time when using APM
2524 support, or if it beeps continuously instead of suspending. Turn
2525 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2526 T400CDT. This is off by default since most machines do fine without
2531 bool "Make CPU Idle calls when idle"
2533 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2534 On some machines, this can activate improved power savings, such as
2535 a slowed CPU clock rate, when the machine is idle. These idle calls
2536 are made after the idle loop has run for some length of time (e.g.,
2537 333 mS). On some machines, this will cause a hang at boot time or
2538 whenever the CPU becomes idle. (On machines with more than one CPU,
2539 this option does nothing.)
2541 config APM_DISPLAY_BLANK
2542 bool "Enable console blanking using APM"
2544 Enable console blanking using the APM. Some laptops can use this to
2545 turn off the LCD backlight when the screen blanker of the Linux
2546 virtual console blanks the screen. Note that this is only used by
2547 the virtual console screen blanker, and won't turn off the backlight
2548 when using the X Window system. This also doesn't have anything to
2549 do with your VESA-compliant power-saving monitor. Further, this
2550 option doesn't work for all laptops -- it might not turn off your
2551 backlight at all, or it might print a lot of errors to the console,
2552 especially if you are using gpm.
2554 config APM_ALLOW_INTS
2555 bool "Allow interrupts during APM BIOS calls"
2557 Normally we disable external interrupts while we are making calls to
2558 the APM BIOS as a measure to lessen the effects of a badly behaving
2559 BIOS implementation. The BIOS should reenable interrupts if it
2560 needs to. Unfortunately, some BIOSes do not -- especially those in
2561 many of the newer IBM Thinkpads. If you experience hangs when you
2562 suspend, try setting this to Y. Otherwise, say N.
2566 source "drivers/cpufreq/Kconfig"
2568 source "drivers/cpuidle/Kconfig"
2570 source "drivers/idle/Kconfig"
2575 menu "Bus options (PCI etc.)"
2578 prompt "PCI access mode"
2579 depends on X86_32 && PCI
2582 On PCI systems, the BIOS can be used to detect the PCI devices and
2583 determine their configuration. However, some old PCI motherboards
2584 have BIOS bugs and may crash if this is done. Also, some embedded
2585 PCI-based systems don't have any BIOS at all. Linux can also try to
2586 detect the PCI hardware directly without using the BIOS.
2588 With this option, you can specify how Linux should detect the
2589 PCI devices. If you choose "BIOS", the BIOS will be used,
2590 if you choose "Direct", the BIOS won't be used, and if you
2591 choose "MMConfig", then PCI Express MMCONFIG will be used.
2592 If you choose "Any", the kernel will try MMCONFIG, then the
2593 direct access method and falls back to the BIOS if that doesn't
2594 work. If unsure, go with the default, which is "Any".
2599 config PCI_GOMMCONFIG
2616 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2618 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2621 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2624 bool "Support mmconfig PCI config space access" if X86_64
2626 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2627 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2631 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2635 depends on PCI && XEN
2638 config MMCONF_FAM10H
2640 depends on X86_64 && PCI_MMCONFIG && ACPI
2642 config PCI_CNB20LE_QUIRK
2643 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2646 Read the PCI windows out of the CNB20LE host bridge. This allows
2647 PCI hotplug to work on systems with the CNB20LE chipset which do
2650 There's no public spec for this chipset, and this functionality
2651 is known to be incomplete.
2653 You should say N unless you know you need this.
2656 bool "ISA bus support on modern systems" if EXPERT
2658 Expose ISA bus device drivers and options available for selection and
2659 configuration. Enable this option if your target machine has an ISA
2660 bus. ISA is an older system, displaced by PCI and newer bus
2661 architectures -- if your target machine is modern, it probably does
2662 not have an ISA bus.
2666 # x86_64 have no ISA slots, but can have ISA-style DMA.
2668 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2671 Enables ISA-style DMA support for devices requiring such controllers.
2679 Find out whether you have ISA slots on your motherboard. ISA is the
2680 name of a bus system, i.e. the way the CPU talks to the other stuff
2681 inside your box. Other bus systems are PCI, EISA, MicroChannel
2682 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2683 newer boards don't support it. If you have ISA, say Y, otherwise N.
2686 tristate "NatSemi SCx200 support"
2688 This provides basic support for National Semiconductor's
2689 (now AMD's) Geode processors. The driver probes for the
2690 PCI-IDs of several on-chip devices, so its a good dependency
2691 for other scx200_* drivers.
2693 If compiled as a module, the driver is named scx200.
2695 config SCx200HR_TIMER
2696 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2700 This driver provides a clocksource built upon the on-chip
2701 27MHz high-resolution timer. Its also a workaround for
2702 NSC Geode SC-1100's buggy TSC, which loses time when the
2703 processor goes idle (as is done by the scheduler). The
2704 other workaround is idle=poll boot option.
2707 bool "One Laptop Per Child support"
2714 Add support for detecting the unique features of the OLPC
2718 bool "OLPC XO-1 Power Management"
2719 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2721 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2724 bool "OLPC XO-1 Real Time Clock"
2725 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2727 Add support for the XO-1 real time clock, which can be used as a
2728 programmable wakeup source.
2731 bool "OLPC XO-1 SCI extras"
2732 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2736 Add support for SCI-based features of the OLPC XO-1 laptop:
2737 - EC-driven system wakeups
2741 - AC adapter status updates
2742 - Battery status updates
2744 config OLPC_XO15_SCI
2745 bool "OLPC XO-1.5 SCI extras"
2746 depends on OLPC && ACPI
2749 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2750 - EC-driven system wakeups
2751 - AC adapter status updates
2752 - Battery status updates
2755 bool "PCEngines ALIX System Support (LED setup)"
2758 This option enables system support for the PCEngines ALIX.
2759 At present this just sets up LEDs for GPIO control on
2760 ALIX2/3/6 boards. However, other system specific setup should
2763 Note: You must still enable the drivers for GPIO and LED support
2764 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2766 Note: You have to set alix.force=1 for boards with Award BIOS.
2769 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2772 This option enables system support for the Soekris Engineering net5501.
2775 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2779 This option enables system support for the Traverse Technologies GEOS.
2782 bool "Technologic Systems TS-5500 platform support"
2784 select CHECK_SIGNATURE
2788 This option enables system support for the Technologic Systems TS-5500.
2794 depends on CPU_SUP_AMD && PCI
2797 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2799 Firmwares often provide initial graphics framebuffers so the BIOS,
2800 bootloader or kernel can show basic video-output during boot for
2801 user-guidance and debugging. Historically, x86 used the VESA BIOS
2802 Extensions and EFI-framebuffers for this, which are mostly limited
2804 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2805 framebuffers so the new generic system-framebuffer drivers can be
2806 used on x86. If the framebuffer is not compatible with the generic
2807 modes, it is advertised as fallback platform framebuffer so legacy
2808 drivers like efifb, vesafb and uvesafb can pick it up.
2809 If this option is not selected, all system framebuffers are always
2810 marked as fallback platform framebuffers as usual.
2812 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2813 not be able to pick up generic system framebuffers if this option
2814 is selected. You are highly encouraged to enable simplefb as
2815 replacement if you select this option. simplefb can correctly deal
2816 with generic system framebuffers. But you should still keep vesafb
2817 and others enabled as fallback if a system framebuffer is
2818 incompatible with simplefb.
2825 menu "Binary Emulations"
2827 config IA32_EMULATION
2828 bool "IA32 Emulation"
2830 select ARCH_WANT_OLD_COMPAT_IPC
2832 select COMPAT_BINFMT_ELF
2833 select COMPAT_OLD_SIGACTION
2835 Include code to run legacy 32-bit programs under a
2836 64-bit kernel. You should likely turn this on, unless you're
2837 100% sure that you don't have any 32-bit programs left.
2840 tristate "IA32 a.out support"
2841 depends on IA32_EMULATION
2844 Support old a.out binaries in the 32bit emulation.
2847 bool "x32 ABI for 64-bit mode"
2850 Include code to run binaries for the x32 native 32-bit ABI
2851 for 64-bit processors. An x32 process gets access to the
2852 full 64-bit register file and wide data path while leaving
2853 pointers at 32 bits for smaller memory footprint.
2855 You will need a recent binutils (2.22 or later) with
2856 elf32_x86_64 support enabled to compile a kernel with this
2861 depends on IA32_EMULATION || X86_32
2863 select OLD_SIGSUSPEND3
2867 depends on IA32_EMULATION || X86_X32
2870 config COMPAT_FOR_U64_ALIGNMENT
2873 config SYSVIPC_COMPAT
2881 config HAVE_ATOMIC_IOMAP
2885 config X86_DEV_DMA_OPS
2887 depends on X86_64 || STA2X11
2889 config X86_DMA_REMAP
2893 config HAVE_GENERIC_GUP
2896 source "drivers/firmware/Kconfig"
2898 source "arch/x86/kvm/Kconfig"