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 HAVE_DEBUG_STACKOVERFLOW
18 select MODULES_USE_ELF_REL
24 # Options that are inherently 64-bit kernel only:
25 select ARCH_HAS_GIGANTIC_PAGE
26 select ARCH_SUPPORTS_INT128
27 select ARCH_USE_CMPXCHG_LOCKREF
28 select HAVE_ARCH_SOFT_DIRTY
29 select MODULES_USE_ELF_RELA
30 select NEED_DMA_MAP_STATE
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_HAS_ACPI_TABLE_UPGRADE if ACPI
51 select ARCH_HAS_DEBUG_VIRTUAL
52 select ARCH_HAS_DEVMEM_IS_ALLOWED
53 select ARCH_HAS_ELF_RANDOMIZE
54 select ARCH_HAS_FAST_MULTIPLIER
55 select ARCH_HAS_FILTER_PGPROT
56 select ARCH_HAS_FORTIFY_SOURCE
57 select ARCH_HAS_GCOV_PROFILE_ALL
58 select ARCH_HAS_KCOV if X86_64
59 select ARCH_HAS_MEMBARRIER_SYNC_CORE
60 select ARCH_HAS_PMEM_API if X86_64
61 select ARCH_HAS_PTE_SPECIAL
62 select ARCH_HAS_REFCOUNT
63 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
64 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
65 select ARCH_HAS_SET_MEMORY
66 select ARCH_HAS_SET_DIRECT_MAP
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
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_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_REGS_AND_STACK_ACCESS_API
186 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
187 select HAVE_FUNCTION_ARG_ACCESS_API
188 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
189 select HAVE_STACK_VALIDATION if X86_64
191 select HAVE_SYSCALL_TRACEPOINTS
192 select HAVE_UNSTABLE_SCHED_CLOCK
193 select HAVE_USER_RETURN_NOTIFIER
194 select HOTPLUG_SMT if SMP
195 select IRQ_FORCED_THREADING
196 select NEED_SG_DMA_LENGTH
197 select PCI_DOMAINS if PCI
198 select PCI_LOCKLESS_CONFIG if PCI
201 select RTC_MC146818_LIB
204 select SYSCTL_EXCEPTION_TRACE
205 select THREAD_INFO_IN_TASK
206 select USER_STACKTRACE_SUPPORT
208 select X86_FEATURE_NAMES if PROC_FS
210 config INSTRUCTION_DECODER
212 depends on KPROBES || PERF_EVENTS || UPROBES
216 default "elf32-i386" if X86_32
217 default "elf64-x86-64" if X86_64
219 config ARCH_DEFCONFIG
221 default "arch/x86/configs/i386_defconfig" if X86_32
222 default "arch/x86/configs/x86_64_defconfig" if X86_64
224 config LOCKDEP_SUPPORT
227 config STACKTRACE_SUPPORT
233 config ARCH_MMAP_RND_BITS_MIN
237 config ARCH_MMAP_RND_BITS_MAX
241 config ARCH_MMAP_RND_COMPAT_BITS_MIN
244 config ARCH_MMAP_RND_COMPAT_BITS_MAX
250 config GENERIC_ISA_DMA
252 depends on ISA_DMA_API
257 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
259 config GENERIC_BUG_RELATIVE_POINTERS
262 config ARCH_MAY_HAVE_PC_FDC
264 depends on ISA_DMA_API
266 config GENERIC_CALIBRATE_DELAY
269 config ARCH_HAS_CPU_RELAX
272 config ARCH_HAS_CACHE_LINE_SIZE
275 config ARCH_HAS_FILTER_PGPROT
278 config HAVE_SETUP_PER_CPU_AREA
281 config NEED_PER_CPU_EMBED_FIRST_CHUNK
284 config NEED_PER_CPU_PAGE_FIRST_CHUNK
287 config ARCH_HIBERNATION_POSSIBLE
290 config ARCH_SUSPEND_POSSIBLE
293 config ARCH_WANT_HUGE_PMD_SHARE
296 config ARCH_WANT_GENERAL_HUGETLB
305 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
308 config KASAN_SHADOW_OFFSET
311 default 0xdffffc0000000000
313 config HAVE_INTEL_TXT
315 depends on INTEL_IOMMU && ACPI
319 depends on X86_32 && SMP
323 depends on X86_64 && SMP
325 config X86_32_LAZY_GS
327 depends on X86_32 && !STACKPROTECTOR
329 config ARCH_SUPPORTS_UPROBES
332 config FIX_EARLYCON_MEM
335 config DYNAMIC_PHYSICAL_MASK
338 config PGTABLE_LEVELS
340 default 5 if X86_5LEVEL
345 config CC_HAS_SANE_STACKPROTECTOR
347 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
348 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
350 We have to make sure stack protector is unconditionally disabled if
351 the compiler produces broken code.
353 menu "Processor type and features"
356 bool "DMA memory allocation support" if EXPERT
359 DMA memory allocation support allows devices with less than 32-bit
360 addressing to allocate within the first 16MB of address space.
361 Disable if no such devices will be used.
366 bool "Symmetric multi-processing support"
368 This enables support for systems with more than one CPU. If you have
369 a system with only one CPU, say N. If you have a system with more
372 If you say N here, the kernel will run on uni- and multiprocessor
373 machines, but will use only one CPU of a multiprocessor machine. If
374 you say Y here, the kernel will run on many, but not all,
375 uniprocessor machines. On a uniprocessor machine, the kernel
376 will run faster if you say N here.
378 Note that if you say Y here and choose architecture "586" or
379 "Pentium" under "Processor family", the kernel will not work on 486
380 architectures. Similarly, multiprocessor kernels for the "PPro"
381 architecture may not work on all Pentium based boards.
383 People using multiprocessor machines who say Y here should also say
384 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
385 Management" code will be disabled if you say Y here.
387 See also <file:Documentation/x86/i386/IO-APIC.txt>,
388 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
389 <http://www.tldp.org/docs.html#howto>.
391 If you don't know what to do here, say N.
393 config X86_FEATURE_NAMES
394 bool "Processor feature human-readable names" if EMBEDDED
397 This option compiles in a table of x86 feature bits and corresponding
398 names. This is required to support /proc/cpuinfo and a few kernel
399 messages. You can disable this to save space, at the expense of
400 making those few kernel messages show numeric feature bits instead.
405 bool "Support x2apic"
406 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
408 This enables x2apic support on CPUs that have this feature.
410 This allows 32-bit apic IDs (so it can support very large systems),
411 and accesses the local apic via MSRs not via mmio.
413 If you don't know what to do here, say N.
416 bool "Enable MPS table" if ACPI || SFI
418 depends on X86_LOCAL_APIC
420 For old smp systems that do not have proper acpi support. Newer systems
421 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
425 depends on X86_GOLDFISH
428 bool "Avoid speculative indirect branches in kernel"
430 select STACK_VALIDATION if HAVE_STACK_VALIDATION
432 Compile kernel with the retpoline compiler options to guard against
433 kernel-to-user data leaks by avoiding speculative indirect
434 branches. Requires a compiler with -mindirect-branch=thunk-extern
435 support for full protection. The kernel may run slower.
437 config X86_CPU_RESCTRL
438 bool "x86 CPU resource control support"
439 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
442 Enable x86 CPU resource control support.
444 Provide support for the allocation and monitoring of system resources
447 Intel calls this Intel Resource Director Technology
448 (Intel(R) RDT). More information about RDT can be found in the
449 Intel x86 Architecture Software Developer Manual.
451 AMD calls this AMD Platform Quality of Service (AMD QoS).
452 More information about AMD QoS can be found in the AMD64 Technology
453 Platform Quality of Service Extensions manual.
459 bool "Support for big SMP systems with more than 8 CPUs"
462 This option is needed for the systems that have more than 8 CPUs
464 config X86_EXTENDED_PLATFORM
465 bool "Support for extended (non-PC) x86 platforms"
468 If you disable this option then the kernel will only support
469 standard PC platforms. (which covers the vast majority of
472 If you enable this option then you'll be able to select support
473 for the following (non-PC) 32 bit x86 platforms:
474 Goldfish (Android emulator)
477 SGI 320/540 (Visual Workstation)
478 STA2X11-based (e.g. Northville)
479 Moorestown MID devices
481 If you have one of these systems, or if you want to build a
482 generic distribution kernel, say Y here - otherwise say N.
486 config X86_EXTENDED_PLATFORM
487 bool "Support for extended (non-PC) x86 platforms"
490 If you disable this option then the kernel will only support
491 standard PC platforms. (which covers the vast majority of
494 If you enable this option then you'll be able to select support
495 for the following (non-PC) 64 bit x86 platforms:
500 If you have one of these systems, or if you want to build a
501 generic distribution kernel, say Y here - otherwise say N.
503 # This is an alphabetically sorted list of 64 bit extended platforms
504 # Please maintain the alphabetic order if and when there are additions
506 bool "Numascale NumaChip"
508 depends on X86_EXTENDED_PLATFORM
511 depends on X86_X2APIC
512 depends on PCI_MMCONFIG
514 Adds support for Numascale NumaChip large-SMP systems. Needed to
515 enable more than ~168 cores.
516 If you don't have one of these, you should say N here.
520 select HYPERVISOR_GUEST
522 depends on X86_64 && PCI
523 depends on X86_EXTENDED_PLATFORM
526 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
527 supposed to run on these EM64T-based machines. Only choose this option
528 if you have one of these machines.
531 bool "SGI Ultraviolet"
533 depends on X86_EXTENDED_PLATFORM
536 depends on X86_X2APIC
539 This option is needed in order to support SGI Ultraviolet systems.
540 If you don't have one of these, you should say N here.
542 # Following is an alphabetically sorted list of 32 bit extended platforms
543 # Please maintain the alphabetic order if and when there are additions
546 bool "Goldfish (Virtual Platform)"
547 depends on X86_EXTENDED_PLATFORM
549 Enable support for the Goldfish virtual platform used primarily
550 for Android development. Unless you are building for the Android
551 Goldfish emulator say N here.
554 bool "CE4100 TV platform"
556 depends on PCI_GODIRECT
557 depends on X86_IO_APIC
559 depends on X86_EXTENDED_PLATFORM
560 select X86_REBOOTFIXUPS
562 select OF_EARLY_FLATTREE
564 Select for the Intel CE media processor (CE4100) SOC.
565 This option compiles in support for the CE4100 SOC for settop
566 boxes and media devices.
569 bool "Intel MID platform support"
570 depends on X86_EXTENDED_PLATFORM
571 depends on X86_PLATFORM_DEVICES
573 depends on X86_64 || (PCI_GOANY && X86_32)
574 depends on X86_IO_APIC
580 select MFD_INTEL_MSIC
582 Select to build a kernel capable of supporting Intel MID (Mobile
583 Internet Device) platform systems which do not have the PCI legacy
584 interfaces. If you are building for a PC class system say N here.
586 Intel MID platforms are based on an Intel processor and chipset which
587 consume less power than most of the x86 derivatives.
589 config X86_INTEL_QUARK
590 bool "Intel Quark platform support"
592 depends on X86_EXTENDED_PLATFORM
593 depends on X86_PLATFORM_DEVICES
597 depends on X86_IO_APIC
602 Select to include support for Quark X1000 SoC.
603 Say Y here if you have a Quark based system such as the Arduino
604 compatible Intel Galileo.
606 config X86_INTEL_LPSS
607 bool "Intel Low Power Subsystem Support"
608 depends on X86 && ACPI && PCI
613 Select to build support for Intel Low Power Subsystem such as
614 found on Intel Lynxpoint PCH. Selecting this option enables
615 things like clock tree (common clock framework) and pincontrol
616 which are needed by the LPSS peripheral drivers.
618 config X86_AMD_PLATFORM_DEVICE
619 bool "AMD ACPI2Platform devices support"
624 Select to interpret AMD specific ACPI device to platform device
625 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
626 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
627 implemented under PINCTRL subsystem.
630 tristate "Intel SoC IOSF Sideband support for SoC platforms"
633 This option enables sideband register access support for Intel SoC
634 platforms. On these platforms the IOSF sideband is used in lieu of
635 MSR's for some register accesses, mostly but not limited to thermal
636 and power. Drivers may query the availability of this device to
637 determine if they need the sideband in order to work on these
638 platforms. The sideband is available on the following SoC products.
639 This list is not meant to be exclusive.
644 You should say Y if you are running a kernel on one of these SoC's.
646 config IOSF_MBI_DEBUG
647 bool "Enable IOSF sideband access through debugfs"
648 depends on IOSF_MBI && DEBUG_FS
650 Select this option to expose the IOSF sideband access registers (MCR,
651 MDR, MCRX) through debugfs to write and read register information from
652 different units on the SoC. This is most useful for obtaining device
653 state information for debug and analysis. As this is a general access
654 mechanism, users of this option would have specific knowledge of the
655 device they want to access.
657 If you don't require the option or are in doubt, say N.
660 bool "RDC R-321x SoC"
662 depends on X86_EXTENDED_PLATFORM
664 select X86_REBOOTFIXUPS
666 This option is needed for RDC R-321x system-on-chip, also known
668 If you don't have one of these chips, you should say N here.
670 config X86_32_NON_STANDARD
671 bool "Support non-standard 32-bit SMP architectures"
672 depends on X86_32 && SMP
673 depends on X86_EXTENDED_PLATFORM
675 This option compiles in the bigsmp and STA2X11 default
676 subarchitectures. It is intended for a generic binary
677 kernel. If you select them all, kernel will probe it one by
678 one and will fallback to default.
680 # Alphabetically sorted list of Non standard 32 bit platforms
682 config X86_SUPPORTS_MEMORY_FAILURE
684 # MCE code calls memory_failure():
686 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
687 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
688 depends on X86_64 || !SPARSEMEM
689 select ARCH_SUPPORTS_MEMORY_FAILURE
692 bool "STA2X11 Companion Chip Support"
693 depends on X86_32_NON_STANDARD && PCI
694 select ARCH_HAS_PHYS_TO_DMA
699 This adds support for boards based on the STA2X11 IO-Hub,
700 a.k.a. "ConneXt". The chip is used in place of the standard
701 PC chipset, so all "standard" peripherals are missing. If this
702 option is selected the kernel will still be able to boot on
703 standard PC machines.
706 tristate "Eurobraille/Iris poweroff module"
709 The Iris machines from EuroBraille do not have APM or ACPI support
710 to shut themselves down properly. A special I/O sequence is
711 needed to do so, which is what this module does at
714 This is only for Iris machines from EuroBraille.
718 config SCHED_OMIT_FRAME_POINTER
720 prompt "Single-depth WCHAN output"
723 Calculate simpler /proc/<PID>/wchan values. If this option
724 is disabled then wchan values will recurse back to the
725 caller function. This provides more accurate wchan values,
726 at the expense of slightly more scheduling overhead.
728 If in doubt, say "Y".
730 menuconfig HYPERVISOR_GUEST
731 bool "Linux guest support"
733 Say Y here to enable options for running Linux under various hyper-
734 visors. This option enables basic hypervisor detection and platform
737 If you say N, all options in this submenu will be skipped and
738 disabled, and Linux guest support won't be built in.
743 bool "Enable paravirtualization code"
745 This changes the kernel so it can modify itself when it is run
746 under a hypervisor, potentially improving performance significantly
747 over full virtualization. However, when run without a hypervisor
748 the kernel is theoretically slower and slightly larger.
753 config PARAVIRT_DEBUG
754 bool "paravirt-ops debugging"
755 depends on PARAVIRT && DEBUG_KERNEL
757 Enable to debug paravirt_ops internals. Specifically, BUG if
758 a paravirt_op is missing when it is called.
760 config PARAVIRT_SPINLOCKS
761 bool "Paravirtualization layer for spinlocks"
762 depends on PARAVIRT && SMP
764 Paravirtualized spinlocks allow a pvops backend to replace the
765 spinlock implementation with something virtualization-friendly
766 (for example, block the virtual CPU rather than spinning).
768 It has a minimal impact on native kernels and gives a nice performance
769 benefit on paravirtualized KVM / Xen kernels.
771 If you are unsure how to answer this question, answer Y.
773 source "arch/x86/xen/Kconfig"
776 bool "KVM Guest support (including kvmclock)"
778 select PARAVIRT_CLOCK
781 This option enables various optimizations for running under the KVM
782 hypervisor. It includes a paravirtualized clock, so that instead
783 of relying on a PIT (or probably other) emulation by the
784 underlying device model, the host provides the guest with
785 timing infrastructure such as time of day, and system time
788 bool "Support for running PVH guests"
790 This option enables the PVH entry point for guest virtual machines
791 as specified in the x86/HVM direct boot ABI.
794 bool "Enable debug information for KVM Guests in debugfs"
795 depends on KVM_GUEST && DEBUG_FS
797 This option enables collection of various statistics for KVM guest.
798 Statistics are displayed in debugfs filesystem. Enabling this option
799 may incur significant overhead.
801 config PARAVIRT_TIME_ACCOUNTING
802 bool "Paravirtual steal time accounting"
805 Select this option to enable fine granularity task steal time
806 accounting. Time spent executing other tasks in parallel with
807 the current vCPU is discounted from the vCPU power. To account for
808 that, there can be a small performance impact.
810 If in doubt, say N here.
812 config PARAVIRT_CLOCK
815 config JAILHOUSE_GUEST
816 bool "Jailhouse non-root cell support"
817 depends on X86_64 && PCI
820 This option allows to run Linux as guest in a Jailhouse non-root
821 cell. You can leave this option disabled if you only want to start
822 Jailhouse and run Linux afterwards in the root cell.
824 endif #HYPERVISOR_GUEST
826 source "arch/x86/Kconfig.cpu"
830 prompt "HPET Timer Support" if X86_32
832 Use the IA-PC HPET (High Precision Event Timer) to manage
833 time in preference to the PIT and RTC, if a HPET is
835 HPET is the next generation timer replacing legacy 8254s.
836 The HPET provides a stable time base on SMP
837 systems, unlike the TSC, but it is more expensive to access,
838 as it is off-chip. The interface used is documented
839 in the HPET spec, revision 1.
841 You can safely choose Y here. However, HPET will only be
842 activated if the platform and the BIOS support this feature.
843 Otherwise the 8254 will be used for timing services.
845 Choose N to continue using the legacy 8254 timer.
847 config HPET_EMULATE_RTC
849 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
852 def_bool y if X86_INTEL_MID
853 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
855 depends on X86_INTEL_MID && SFI
857 APB timer is the replacement for 8254, HPET on X86 MID platforms.
858 The APBT provides a stable time base on SMP
859 systems, unlike the TSC, but it is more expensive to access,
860 as it is off-chip. APB timers are always running regardless of CPU
861 C states, they are used as per CPU clockevent device when possible.
863 # Mark as expert because too many people got it wrong.
864 # The code disables itself when not needed.
867 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
868 bool "Enable DMI scanning" if EXPERT
870 Enabled scanning of DMI to identify machine quirks. Say Y
871 here unless you have verified that your setup is not
872 affected by entries in the DMI blacklist. Required by PNP
876 bool "Old AMD GART IOMMU support"
879 depends on X86_64 && PCI && AMD_NB
881 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
882 GART based hardware IOMMUs.
884 The GART supports full DMA access for devices with 32-bit access
885 limitations, on systems with more than 3 GB. This is usually needed
886 for USB, sound, many IDE/SATA chipsets and some other devices.
888 Newer systems typically have a modern AMD IOMMU, supported via
889 the CONFIG_AMD_IOMMU=y config option.
891 In normal configurations this driver is only active when needed:
892 there's more than 3 GB of memory and the system contains a
893 32-bit limited device.
898 bool "IBM Calgary IOMMU support"
901 depends on X86_64 && PCI
903 Support for hardware IOMMUs in IBM's xSeries x366 and x460
904 systems. Needed to run systems with more than 3GB of memory
905 properly with 32-bit PCI devices that do not support DAC
906 (Double Address Cycle). Calgary also supports bus level
907 isolation, where all DMAs pass through the IOMMU. This
908 prevents them from going anywhere except their intended
909 destination. This catches hard-to-find kernel bugs and
910 mis-behaving drivers and devices that do not use the DMA-API
911 properly to set up their DMA buffers. The IOMMU can be
912 turned off at boot time with the iommu=off parameter.
913 Normally the kernel will make the right choice by itself.
916 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
918 prompt "Should Calgary be enabled by default?"
919 depends on CALGARY_IOMMU
921 Should Calgary be enabled by default? if you choose 'y', Calgary
922 will be used (if it exists). If you choose 'n', Calgary will not be
923 used even if it exists. If you choose 'n' and would like to use
924 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
928 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
929 depends on X86_64 && SMP && DEBUG_KERNEL
930 select CPUMASK_OFFSTACK
932 Enable maximum number of CPUS and NUMA Nodes for this architecture.
936 # The maximum number of CPUs supported:
938 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
939 # and which can be configured interactively in the
940 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
942 # The ranges are different on 32-bit and 64-bit kernels, depending on
943 # hardware capabilities and scalability features of the kernel.
945 # ( If MAXSMP is enabled we just use the highest possible value and disable
946 # interactive configuration. )
949 config NR_CPUS_RANGE_BEGIN
951 default NR_CPUS_RANGE_END if MAXSMP
955 config NR_CPUS_RANGE_END
958 default 64 if SMP && X86_BIGSMP
959 default 8 if SMP && !X86_BIGSMP
962 config NR_CPUS_RANGE_END
965 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
966 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
969 config NR_CPUS_DEFAULT
972 default 32 if X86_BIGSMP
976 config NR_CPUS_DEFAULT
979 default 8192 if MAXSMP
984 int "Maximum number of CPUs" if SMP && !MAXSMP
985 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
986 default NR_CPUS_DEFAULT
988 This allows you to specify the maximum number of CPUs which this
989 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
990 supported value is 8192, otherwise the maximum value is 512. The
991 minimum value which makes sense is 2.
993 This is purely to save memory: each supported CPU adds about 8KB
1001 prompt "Multi-core scheduler support"
1004 Multi-core scheduler support improves the CPU scheduler's decision
1005 making when dealing with multi-core CPU chips at a cost of slightly
1006 increased overhead in some places. If unsure say N here.
1008 config SCHED_MC_PRIO
1009 bool "CPU core priorities scheduler support"
1010 depends on SCHED_MC && CPU_SUP_INTEL
1011 select X86_INTEL_PSTATE
1015 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1016 core ordering determined at manufacturing time, which allows
1017 certain cores to reach higher turbo frequencies (when running
1018 single threaded workloads) than others.
1020 Enabling this kernel feature teaches the scheduler about
1021 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1022 scheduler's CPU selection logic accordingly, so that higher
1023 overall system performance can be achieved.
1025 This feature will have no effect on CPUs without this feature.
1027 If unsure say Y here.
1031 depends on !SMP && X86_LOCAL_APIC
1034 bool "Local APIC support on uniprocessors" if !PCI_MSI
1036 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1038 A local APIC (Advanced Programmable Interrupt Controller) is an
1039 integrated interrupt controller in the CPU. If you have a single-CPU
1040 system which has a processor with a local APIC, you can say Y here to
1041 enable and use it. If you say Y here even though your machine doesn't
1042 have a local APIC, then the kernel will still run with no slowdown at
1043 all. The local APIC supports CPU-generated self-interrupts (timer,
1044 performance counters), and the NMI watchdog which detects hard
1047 config X86_UP_IOAPIC
1048 bool "IO-APIC support on uniprocessors"
1049 depends on X86_UP_APIC
1051 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1052 SMP-capable replacement for PC-style interrupt controllers. Most
1053 SMP systems and many recent uniprocessor systems have one.
1055 If you have a single-CPU system with an IO-APIC, you can say Y here
1056 to use it. If you say Y here even though your machine doesn't have
1057 an IO-APIC, then the kernel will still run with no slowdown at all.
1059 config X86_LOCAL_APIC
1061 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1062 select IRQ_DOMAIN_HIERARCHY
1063 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1067 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1069 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1070 bool "Reroute for broken boot IRQs"
1071 depends on X86_IO_APIC
1073 This option enables a workaround that fixes a source of
1074 spurious interrupts. This is recommended when threaded
1075 interrupt handling is used on systems where the generation of
1076 superfluous "boot interrupts" cannot be disabled.
1078 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1079 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1080 kernel does during interrupt handling). On chipsets where this
1081 boot IRQ generation cannot be disabled, this workaround keeps
1082 the original IRQ line masked so that only the equivalent "boot
1083 IRQ" is delivered to the CPUs. The workaround also tells the
1084 kernel to set up the IRQ handler on the boot IRQ line. In this
1085 way only one interrupt is delivered to the kernel. Otherwise
1086 the spurious second interrupt may cause the kernel to bring
1087 down (vital) interrupt lines.
1089 Only affects "broken" chipsets. Interrupt sharing may be
1090 increased on these systems.
1093 bool "Machine Check / overheating reporting"
1094 select GENERIC_ALLOCATOR
1097 Machine Check support allows the processor to notify the
1098 kernel if it detects a problem (e.g. overheating, data corruption).
1099 The action the kernel takes depends on the severity of the problem,
1100 ranging from warning messages to halting the machine.
1102 config X86_MCELOG_LEGACY
1103 bool "Support for deprecated /dev/mcelog character device"
1106 Enable support for /dev/mcelog which is needed by the old mcelog
1107 userspace logging daemon. Consider switching to the new generation
1110 config X86_MCE_INTEL
1112 prompt "Intel MCE features"
1113 depends on X86_MCE && X86_LOCAL_APIC
1115 Additional support for intel specific MCE features such as
1116 the thermal monitor.
1120 prompt "AMD MCE features"
1121 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1123 Additional support for AMD specific MCE features such as
1124 the DRAM Error Threshold.
1126 config X86_ANCIENT_MCE
1127 bool "Support for old Pentium 5 / WinChip machine checks"
1128 depends on X86_32 && X86_MCE
1130 Include support for machine check handling on old Pentium 5 or WinChip
1131 systems. These typically need to be enabled explicitly on the command
1134 config X86_MCE_THRESHOLD
1135 depends on X86_MCE_AMD || X86_MCE_INTEL
1138 config X86_MCE_INJECT
1139 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1140 tristate "Machine check injector support"
1142 Provide support for injecting machine checks for testing purposes.
1143 If you don't know what a machine check is and you don't do kernel
1144 QA it is safe to say n.
1146 config X86_THERMAL_VECTOR
1148 depends on X86_MCE_INTEL
1150 source "arch/x86/events/Kconfig"
1152 config X86_LEGACY_VM86
1153 bool "Legacy VM86 support"
1156 This option allows user programs to put the CPU into V8086
1157 mode, which is an 80286-era approximation of 16-bit real mode.
1159 Some very old versions of X and/or vbetool require this option
1160 for user mode setting. Similarly, DOSEMU will use it if
1161 available to accelerate real mode DOS programs. However, any
1162 recent version of DOSEMU, X, or vbetool should be fully
1163 functional even without kernel VM86 support, as they will all
1164 fall back to software emulation. Nevertheless, if you are using
1165 a 16-bit DOS program where 16-bit performance matters, vm86
1166 mode might be faster than emulation and you might want to
1169 Note that any app that works on a 64-bit kernel is unlikely to
1170 need this option, as 64-bit kernels don't, and can't, support
1171 V8086 mode. This option is also unrelated to 16-bit protected
1172 mode and is not needed to run most 16-bit programs under Wine.
1174 Enabling this option increases the complexity of the kernel
1175 and slows down exception handling a tiny bit.
1177 If unsure, say N here.
1181 default X86_LEGACY_VM86
1184 bool "Enable support for 16-bit segments" if EXPERT
1186 depends on MODIFY_LDT_SYSCALL
1188 This option is required by programs like Wine to run 16-bit
1189 protected mode legacy code on x86 processors. Disabling
1190 this option saves about 300 bytes on i386, or around 6K text
1191 plus 16K runtime memory on x86-64,
1195 depends on X86_16BIT && X86_32
1199 depends on X86_16BIT && X86_64
1201 config X86_VSYSCALL_EMULATION
1202 bool "Enable vsyscall emulation" if EXPERT
1206 This enables emulation of the legacy vsyscall page. Disabling
1207 it is roughly equivalent to booting with vsyscall=none, except
1208 that it will also disable the helpful warning if a program
1209 tries to use a vsyscall. With this option set to N, offending
1210 programs will just segfault, citing addresses of the form
1213 This option is required by many programs built before 2013, and
1214 care should be used even with newer programs if set to N.
1216 Disabling this option saves about 7K of kernel size and
1217 possibly 4K of additional runtime pagetable memory.
1220 tristate "Toshiba Laptop support"
1223 This adds a driver to safely access the System Management Mode of
1224 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1225 not work on models with a Phoenix BIOS. The System Management Mode
1226 is used to set the BIOS and power saving options on Toshiba portables.
1228 For information on utilities to make use of this driver see the
1229 Toshiba Linux utilities web site at:
1230 <http://www.buzzard.org.uk/toshiba/>.
1232 Say Y if you intend to run this kernel on a Toshiba portable.
1236 tristate "Dell i8k legacy laptop support"
1238 select SENSORS_DELL_SMM
1240 This option enables legacy /proc/i8k userspace interface in hwmon
1241 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1242 temperature and allows controlling fan speeds of Dell laptops via
1243 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1244 it reports also power and hotkey status. For fan speed control is
1245 needed userspace package i8kutils.
1247 Say Y if you intend to run this kernel on old Dell laptops or want to
1248 use userspace package i8kutils.
1251 config X86_REBOOTFIXUPS
1252 bool "Enable X86 board specific fixups for reboot"
1255 This enables chipset and/or board specific fixups to be done
1256 in order to get reboot to work correctly. This is only needed on
1257 some combinations of hardware and BIOS. The symptom, for which
1258 this config is intended, is when reboot ends with a stalled/hung
1261 Currently, the only fixup is for the Geode machines using
1262 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1264 Say Y if you want to enable the fixup. Currently, it's safe to
1265 enable this option even if you don't need it.
1269 bool "CPU microcode loading support"
1271 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1274 If you say Y here, you will be able to update the microcode on
1275 Intel and AMD processors. The Intel support is for the IA32 family,
1276 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1277 AMD support is for families 0x10 and later. You will obviously need
1278 the actual microcode binary data itself which is not shipped with
1281 The preferred method to load microcode from a detached initrd is described
1282 in Documentation/x86/microcode.txt. For that you need to enable
1283 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1284 initrd for microcode blobs.
1286 In addition, you can build the microcode into the kernel. For that you
1287 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1290 config MICROCODE_INTEL
1291 bool "Intel microcode loading support"
1292 depends on MICROCODE
1296 This options enables microcode patch loading support for Intel
1299 For the current Intel microcode data package go to
1300 <https://downloadcenter.intel.com> and search for
1301 'Linux Processor Microcode Data File'.
1303 config MICROCODE_AMD
1304 bool "AMD microcode loading support"
1305 depends on MICROCODE
1308 If you select this option, microcode patch loading support for AMD
1309 processors will be enabled.
1311 config MICROCODE_OLD_INTERFACE
1312 bool "Ancient loading interface (DEPRECATED)"
1314 depends on MICROCODE
1316 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1317 which was used by userspace tools like iucode_tool and microcode.ctl.
1318 It is inadequate because it runs too late to be able to properly
1319 load microcode on a machine and it needs special tools. Instead, you
1320 should've switched to the early loading method with the initrd or
1321 builtin microcode by now: Documentation/x86/microcode.txt
1324 tristate "/dev/cpu/*/msr - Model-specific register support"
1326 This device gives privileged processes access to the x86
1327 Model-Specific Registers (MSRs). It is a character device with
1328 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1329 MSR accesses are directed to a specific CPU on multi-processor
1333 tristate "/dev/cpu/*/cpuid - CPU information support"
1335 This device gives processes access to the x86 CPUID instruction to
1336 be executed on a specific processor. It is a character device
1337 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1341 prompt "High Memory Support"
1348 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1349 However, the address space of 32-bit x86 processors is only 4
1350 Gigabytes large. That means that, if you have a large amount of
1351 physical memory, not all of it can be "permanently mapped" by the
1352 kernel. The physical memory that's not permanently mapped is called
1355 If you are compiling a kernel which will never run on a machine with
1356 more than 1 Gigabyte total physical RAM, answer "off" here (default
1357 choice and suitable for most users). This will result in a "3GB/1GB"
1358 split: 3GB are mapped so that each process sees a 3GB virtual memory
1359 space and the remaining part of the 4GB virtual memory space is used
1360 by the kernel to permanently map as much physical memory as
1363 If the machine has between 1 and 4 Gigabytes physical RAM, then
1366 If more than 4 Gigabytes is used then answer "64GB" here. This
1367 selection turns Intel PAE (Physical Address Extension) mode on.
1368 PAE implements 3-level paging on IA32 processors. PAE is fully
1369 supported by Linux, PAE mode is implemented on all recent Intel
1370 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1371 then the kernel will not boot on CPUs that don't support PAE!
1373 The actual amount of total physical memory will either be
1374 auto detected or can be forced by using a kernel command line option
1375 such as "mem=256M". (Try "man bootparam" or see the documentation of
1376 your boot loader (lilo or loadlin) about how to pass options to the
1377 kernel at boot time.)
1379 If unsure, say "off".
1384 Select this if you have a 32-bit processor and between 1 and 4
1385 gigabytes of physical RAM.
1389 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1392 Select this if you have a 32-bit processor and more than 4
1393 gigabytes of physical RAM.
1398 prompt "Memory split" if EXPERT
1402 Select the desired split between kernel and user memory.
1404 If the address range available to the kernel is less than the
1405 physical memory installed, the remaining memory will be available
1406 as "high memory". Accessing high memory is a little more costly
1407 than low memory, as it needs to be mapped into the kernel first.
1408 Note that increasing the kernel address space limits the range
1409 available to user programs, making the address space there
1410 tighter. Selecting anything other than the default 3G/1G split
1411 will also likely make your kernel incompatible with binary-only
1414 If you are not absolutely sure what you are doing, leave this
1418 bool "3G/1G user/kernel split"
1419 config VMSPLIT_3G_OPT
1421 bool "3G/1G user/kernel split (for full 1G low memory)"
1423 bool "2G/2G user/kernel split"
1424 config VMSPLIT_2G_OPT
1426 bool "2G/2G user/kernel split (for full 2G low memory)"
1428 bool "1G/3G user/kernel split"
1433 default 0xB0000000 if VMSPLIT_3G_OPT
1434 default 0x80000000 if VMSPLIT_2G
1435 default 0x78000000 if VMSPLIT_2G_OPT
1436 default 0x40000000 if VMSPLIT_1G
1442 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1445 bool "PAE (Physical Address Extension) Support"
1446 depends on X86_32 && !HIGHMEM4G
1447 select PHYS_ADDR_T_64BIT
1450 PAE is required for NX support, and furthermore enables
1451 larger swapspace support for non-overcommit purposes. It
1452 has the cost of more pagetable lookup overhead, and also
1453 consumes more pagetable space per process.
1456 bool "Enable 5-level page tables support"
1457 select DYNAMIC_MEMORY_LAYOUT
1458 select SPARSEMEM_VMEMMAP
1461 5-level paging enables access to larger address space:
1462 upto 128 PiB of virtual address space and 4 PiB of
1463 physical address space.
1465 It will be supported by future Intel CPUs.
1467 A kernel with the option enabled can be booted on machines that
1468 support 4- or 5-level paging.
1470 See Documentation/x86/x86_64/5level-paging.txt for more
1475 config X86_DIRECT_GBPAGES
1477 depends on X86_64 && !DEBUG_PAGEALLOC
1479 Certain kernel features effectively disable kernel
1480 linear 1 GB mappings (even if the CPU otherwise
1481 supports them), so don't confuse the user by printing
1482 that we have them enabled.
1484 config X86_CPA_STATISTICS
1485 bool "Enable statistic for Change Page Attribute"
1488 Expose statistics about the Change Page Attribute mechanims, which
1489 helps to determine the effectiveness of preserving large and huge
1490 page mappings when mapping protections are changed.
1492 config ARCH_HAS_MEM_ENCRYPT
1495 config AMD_MEM_ENCRYPT
1496 bool "AMD Secure Memory Encryption (SME) support"
1497 depends on X86_64 && CPU_SUP_AMD
1498 select DYNAMIC_PHYSICAL_MASK
1499 select ARCH_USE_MEMREMAP_PROT
1501 Say yes to enable support for the encryption of system memory.
1502 This requires an AMD processor that supports Secure Memory
1505 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1506 bool "Activate AMD Secure Memory Encryption (SME) by default"
1508 depends on AMD_MEM_ENCRYPT
1510 Say yes to have system memory encrypted by default if running on
1511 an AMD processor that supports Secure Memory Encryption (SME).
1513 If set to Y, then the encryption of system memory can be
1514 deactivated with the mem_encrypt=off command line option.
1516 If set to N, then the encryption of system memory can be
1517 activated with the mem_encrypt=on command line option.
1519 # Common NUMA Features
1521 bool "Numa Memory Allocation and Scheduler Support"
1523 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1524 default y if X86_BIGSMP
1526 Enable NUMA (Non Uniform Memory Access) support.
1528 The kernel will try to allocate memory used by a CPU on the
1529 local memory controller of the CPU and add some more
1530 NUMA awareness to the kernel.
1532 For 64-bit this is recommended if the system is Intel Core i7
1533 (or later), AMD Opteron, or EM64T NUMA.
1535 For 32-bit this is only needed if you boot a 32-bit
1536 kernel on a 64-bit NUMA platform.
1538 Otherwise, you should say N.
1542 prompt "Old style AMD Opteron NUMA detection"
1543 depends on X86_64 && NUMA && PCI
1545 Enable AMD NUMA node topology detection. You should say Y here if
1546 you have a multi processor AMD system. This uses an old method to
1547 read the NUMA configuration directly from the builtin Northbridge
1548 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1549 which also takes priority if both are compiled in.
1551 config X86_64_ACPI_NUMA
1553 prompt "ACPI NUMA detection"
1554 depends on X86_64 && NUMA && ACPI && PCI
1557 Enable ACPI SRAT based node topology detection.
1559 # Some NUMA nodes have memory ranges that span
1560 # other nodes. Even though a pfn is valid and
1561 # between a node's start and end pfns, it may not
1562 # reside on that node. See memmap_init_zone()
1564 config NODES_SPAN_OTHER_NODES
1566 depends on X86_64_ACPI_NUMA
1569 bool "NUMA emulation"
1572 Enable NUMA emulation. A flat machine will be split
1573 into virtual nodes when booted with "numa=fake=N", where N is the
1574 number of nodes. This is only useful for debugging.
1577 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1579 default "10" if MAXSMP
1580 default "6" if X86_64
1582 depends on NEED_MULTIPLE_NODES
1584 Specify the maximum number of NUMA Nodes available on the target
1585 system. Increases memory reserved to accommodate various tables.
1587 config ARCH_HAVE_MEMORY_PRESENT
1589 depends on X86_32 && DISCONTIGMEM
1591 config ARCH_FLATMEM_ENABLE
1593 depends on X86_32 && !NUMA
1595 config ARCH_DISCONTIGMEM_ENABLE
1597 depends on NUMA && X86_32
1600 config ARCH_SPARSEMEM_ENABLE
1602 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1603 select SPARSEMEM_STATIC if X86_32
1604 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1606 config ARCH_SPARSEMEM_DEFAULT
1607 def_bool X86_64 || (NUMA && X86_32)
1609 config ARCH_SELECT_MEMORY_MODEL
1611 depends on ARCH_SPARSEMEM_ENABLE
1613 config ARCH_MEMORY_PROBE
1614 bool "Enable sysfs memory/probe interface"
1615 depends on X86_64 && MEMORY_HOTPLUG
1617 This option enables a sysfs memory/probe interface for testing.
1618 See Documentation/memory-hotplug.txt for more information.
1619 If you are unsure how to answer this question, answer N.
1621 config ARCH_PROC_KCORE_TEXT
1623 depends on X86_64 && PROC_KCORE
1625 config ILLEGAL_POINTER_VALUE
1628 default 0xdead000000000000 if X86_64
1630 config X86_PMEM_LEGACY_DEVICE
1633 config X86_PMEM_LEGACY
1634 tristate "Support non-standard NVDIMMs and ADR protected memory"
1635 depends on PHYS_ADDR_T_64BIT
1637 select X86_PMEM_LEGACY_DEVICE
1640 Treat memory marked using the non-standard e820 type of 12 as used
1641 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1642 The kernel will offer these regions to the 'pmem' driver so
1643 they can be used for persistent storage.
1648 bool "Allocate 3rd-level pagetables from highmem"
1651 The VM uses one page table entry for each page of physical memory.
1652 For systems with a lot of RAM, this can be wasteful of precious
1653 low memory. Setting this option will put user-space page table
1654 entries in high memory.
1656 config X86_CHECK_BIOS_CORRUPTION
1657 bool "Check for low memory corruption"
1659 Periodically check for memory corruption in low memory, which
1660 is suspected to be caused by BIOS. Even when enabled in the
1661 configuration, it is disabled at runtime. Enable it by
1662 setting "memory_corruption_check=1" on the kernel command
1663 line. By default it scans the low 64k of memory every 60
1664 seconds; see the memory_corruption_check_size and
1665 memory_corruption_check_period parameters in
1666 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1668 When enabled with the default parameters, this option has
1669 almost no overhead, as it reserves a relatively small amount
1670 of memory and scans it infrequently. It both detects corruption
1671 and prevents it from affecting the running system.
1673 It is, however, intended as a diagnostic tool; if repeatable
1674 BIOS-originated corruption always affects the same memory,
1675 you can use memmap= to prevent the kernel from using that
1678 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1679 bool "Set the default setting of memory_corruption_check"
1680 depends on X86_CHECK_BIOS_CORRUPTION
1683 Set whether the default state of memory_corruption_check is
1686 config X86_RESERVE_LOW
1687 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1691 Specify the amount of low memory to reserve for the BIOS.
1693 The first page contains BIOS data structures that the kernel
1694 must not use, so that page must always be reserved.
1696 By default we reserve the first 64K of physical RAM, as a
1697 number of BIOSes are known to corrupt that memory range
1698 during events such as suspend/resume or monitor cable
1699 insertion, so it must not be used by the kernel.
1701 You can set this to 4 if you are absolutely sure that you
1702 trust the BIOS to get all its memory reservations and usages
1703 right. If you know your BIOS have problems beyond the
1704 default 64K area, you can set this to 640 to avoid using the
1705 entire low memory range.
1707 If you have doubts about the BIOS (e.g. suspend/resume does
1708 not work or there's kernel crashes after certain hardware
1709 hotplug events) then you might want to enable
1710 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1711 typical corruption patterns.
1713 Leave this to the default value of 64 if you are unsure.
1715 config MATH_EMULATION
1717 depends on MODIFY_LDT_SYSCALL
1718 prompt "Math emulation" if X86_32
1720 Linux can emulate a math coprocessor (used for floating point
1721 operations) if you don't have one. 486DX and Pentium processors have
1722 a math coprocessor built in, 486SX and 386 do not, unless you added
1723 a 487DX or 387, respectively. (The messages during boot time can
1724 give you some hints here ["man dmesg"].) Everyone needs either a
1725 coprocessor or this emulation.
1727 If you don't have a math coprocessor, you need to say Y here; if you
1728 say Y here even though you have a coprocessor, the coprocessor will
1729 be used nevertheless. (This behavior can be changed with the kernel
1730 command line option "no387", which comes handy if your coprocessor
1731 is broken. Try "man bootparam" or see the documentation of your boot
1732 loader (lilo or loadlin) about how to pass options to the kernel at
1733 boot time.) This means that it is a good idea to say Y here if you
1734 intend to use this kernel on different machines.
1736 More information about the internals of the Linux math coprocessor
1737 emulation can be found in <file:arch/x86/math-emu/README>.
1739 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1740 kernel, it won't hurt.
1744 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1746 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1747 the Memory Type Range Registers (MTRRs) may be used to control
1748 processor access to memory ranges. This is most useful if you have
1749 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1750 allows bus write transfers to be combined into a larger transfer
1751 before bursting over the PCI/AGP bus. This can increase performance
1752 of image write operations 2.5 times or more. Saying Y here creates a
1753 /proc/mtrr file which may be used to manipulate your processor's
1754 MTRRs. Typically the X server should use this.
1756 This code has a reasonably generic interface so that similar
1757 control registers on other processors can be easily supported
1760 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1761 Registers (ARRs) which provide a similar functionality to MTRRs. For
1762 these, the ARRs are used to emulate the MTRRs.
1763 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1764 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1765 write-combining. All of these processors are supported by this code
1766 and it makes sense to say Y here if you have one of them.
1768 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1769 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1770 can lead to all sorts of problems, so it's good to say Y here.
1772 You can safely say Y even if your machine doesn't have MTRRs, you'll
1773 just add about 9 KB to your kernel.
1775 See <file:Documentation/x86/mtrr.txt> for more information.
1777 config MTRR_SANITIZER
1779 prompt "MTRR cleanup support"
1782 Convert MTRR layout from continuous to discrete, so X drivers can
1783 add writeback entries.
1785 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1786 The largest mtrr entry size for a continuous block can be set with
1791 config MTRR_SANITIZER_ENABLE_DEFAULT
1792 int "MTRR cleanup enable value (0-1)"
1795 depends on MTRR_SANITIZER
1797 Enable mtrr cleanup default value
1799 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1800 int "MTRR cleanup spare reg num (0-7)"
1803 depends on MTRR_SANITIZER
1805 mtrr cleanup spare entries default, it can be changed via
1806 mtrr_spare_reg_nr=N on the kernel command line.
1810 prompt "x86 PAT support" if EXPERT
1813 Use PAT attributes to setup page level cache control.
1815 PATs are the modern equivalents of MTRRs and are much more
1816 flexible than MTRRs.
1818 Say N here if you see bootup problems (boot crash, boot hang,
1819 spontaneous reboots) or a non-working video driver.
1823 config ARCH_USES_PG_UNCACHED
1829 prompt "x86 architectural random number generator" if EXPERT
1831 Enable the x86 architectural RDRAND instruction
1832 (Intel Bull Mountain technology) to generate random numbers.
1833 If supported, this is a high bandwidth, cryptographically
1834 secure hardware random number generator.
1838 prompt "Supervisor Mode Access Prevention" if EXPERT
1840 Supervisor Mode Access Prevention (SMAP) is a security
1841 feature in newer Intel processors. There is a small
1842 performance cost if this enabled and turned on; there is
1843 also a small increase in the kernel size if this is enabled.
1847 config X86_INTEL_UMIP
1849 depends on CPU_SUP_INTEL
1850 prompt "Intel User Mode Instruction Prevention" if EXPERT
1852 The User Mode Instruction Prevention (UMIP) is a security
1853 feature in newer Intel processors. If enabled, a general
1854 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1855 or STR instructions are executed in user mode. These instructions
1856 unnecessarily expose information about the hardware state.
1858 The vast majority of applications do not use these instructions.
1859 For the very few that do, software emulation is provided in
1860 specific cases in protected and virtual-8086 modes. Emulated
1863 config X86_INTEL_MPX
1864 prompt "Intel MPX (Memory Protection Extensions)"
1866 # Note: only available in 64-bit mode due to VMA flags shortage
1867 depends on CPU_SUP_INTEL && X86_64
1868 select ARCH_USES_HIGH_VMA_FLAGS
1870 MPX provides hardware features that can be used in
1871 conjunction with compiler-instrumented code to check
1872 memory references. It is designed to detect buffer
1873 overflow or underflow bugs.
1875 This option enables running applications which are
1876 instrumented or otherwise use MPX. It does not use MPX
1877 itself inside the kernel or to protect the kernel
1878 against bad memory references.
1880 Enabling this option will make the kernel larger:
1881 ~8k of kernel text and 36 bytes of data on a 64-bit
1882 defconfig. It adds a long to the 'mm_struct' which
1883 will increase the kernel memory overhead of each
1884 process and adds some branches to paths used during
1885 exec() and munmap().
1887 For details, see Documentation/x86/intel_mpx.txt
1891 config X86_INTEL_MEMORY_PROTECTION_KEYS
1892 prompt "Intel Memory Protection Keys"
1894 # Note: only available in 64-bit mode
1895 depends on CPU_SUP_INTEL && X86_64
1896 select ARCH_USES_HIGH_VMA_FLAGS
1897 select ARCH_HAS_PKEYS
1899 Memory Protection Keys provides a mechanism for enforcing
1900 page-based protections, but without requiring modification of the
1901 page tables when an application changes protection domains.
1903 For details, see Documentation/x86/protection-keys.txt
1908 bool "EFI runtime service support"
1911 select EFI_RUNTIME_WRAPPERS
1913 This enables the kernel to use EFI runtime services that are
1914 available (such as the EFI variable services).
1916 This option is only useful on systems that have EFI firmware.
1917 In addition, you should use the latest ELILO loader available
1918 at <http://elilo.sourceforge.net> in order to take advantage
1919 of EFI runtime services. However, even with this option, the
1920 resultant kernel should continue to boot on existing non-EFI
1924 bool "EFI stub support"
1925 depends on EFI && !X86_USE_3DNOW
1928 This kernel feature allows a bzImage to be loaded directly
1929 by EFI firmware without the use of a bootloader.
1931 See Documentation/efi-stub.txt for more information.
1934 bool "EFI mixed-mode support"
1935 depends on EFI_STUB && X86_64
1937 Enabling this feature allows a 64-bit kernel to be booted
1938 on a 32-bit firmware, provided that your CPU supports 64-bit
1941 Note that it is not possible to boot a mixed-mode enabled
1942 kernel via the EFI boot stub - a bootloader that supports
1943 the EFI handover protocol must be used.
1949 prompt "Enable seccomp to safely compute untrusted bytecode"
1951 This kernel feature is useful for number crunching applications
1952 that may need to compute untrusted bytecode during their
1953 execution. By using pipes or other transports made available to
1954 the process as file descriptors supporting the read/write
1955 syscalls, it's possible to isolate those applications in
1956 their own address space using seccomp. Once seccomp is
1957 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1958 and the task is only allowed to execute a few safe syscalls
1959 defined by each seccomp mode.
1961 If unsure, say Y. Only embedded should say N here.
1963 source "kernel/Kconfig.hz"
1966 bool "kexec system call"
1969 kexec is a system call that implements the ability to shutdown your
1970 current kernel, and to start another kernel. It is like a reboot
1971 but it is independent of the system firmware. And like a reboot
1972 you can start any kernel with it, not just Linux.
1974 The name comes from the similarity to the exec system call.
1976 It is an ongoing process to be certain the hardware in a machine
1977 is properly shutdown, so do not be surprised if this code does not
1978 initially work for you. As of this writing the exact hardware
1979 interface is strongly in flux, so no good recommendation can be
1983 bool "kexec file based system call"
1988 depends on CRYPTO_SHA256=y
1990 This is new version of kexec system call. This system call is
1991 file based and takes file descriptors as system call argument
1992 for kernel and initramfs as opposed to list of segments as
1993 accepted by previous system call.
1995 config ARCH_HAS_KEXEC_PURGATORY
1998 config KEXEC_VERIFY_SIG
1999 bool "Verify kernel signature during kexec_file_load() syscall"
2000 depends on KEXEC_FILE
2002 This option makes kernel signature verification mandatory for
2003 the kexec_file_load() syscall.
2005 In addition to that option, you need to enable signature
2006 verification for the corresponding kernel image type being
2007 loaded in order for this to work.
2009 config KEXEC_BZIMAGE_VERIFY_SIG
2010 bool "Enable bzImage signature verification support"
2011 depends on KEXEC_VERIFY_SIG
2012 depends on SIGNED_PE_FILE_VERIFICATION
2013 select SYSTEM_TRUSTED_KEYRING
2015 Enable bzImage signature verification support.
2018 bool "kernel crash dumps"
2019 depends on X86_64 || (X86_32 && HIGHMEM)
2021 Generate crash dump after being started by kexec.
2022 This should be normally only set in special crash dump kernels
2023 which are loaded in the main kernel with kexec-tools into
2024 a specially reserved region and then later executed after
2025 a crash by kdump/kexec. The crash dump kernel must be compiled
2026 to a memory address not used by the main kernel or BIOS using
2027 PHYSICAL_START, or it must be built as a relocatable image
2028 (CONFIG_RELOCATABLE=y).
2029 For more details see Documentation/kdump/kdump.txt
2033 depends on KEXEC && HIBERNATION
2035 Jump between original kernel and kexeced kernel and invoke
2036 code in physical address mode via KEXEC
2038 config PHYSICAL_START
2039 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2042 This gives the physical address where the kernel is loaded.
2044 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2045 bzImage will decompress itself to above physical address and
2046 run from there. Otherwise, bzImage will run from the address where
2047 it has been loaded by the boot loader and will ignore above physical
2050 In normal kdump cases one does not have to set/change this option
2051 as now bzImage can be compiled as a completely relocatable image
2052 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2053 address. This option is mainly useful for the folks who don't want
2054 to use a bzImage for capturing the crash dump and want to use a
2055 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2056 to be specifically compiled to run from a specific memory area
2057 (normally a reserved region) and this option comes handy.
2059 So if you are using bzImage for capturing the crash dump,
2060 leave the value here unchanged to 0x1000000 and set
2061 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2062 for capturing the crash dump change this value to start of
2063 the reserved region. In other words, it can be set based on
2064 the "X" value as specified in the "crashkernel=YM@XM"
2065 command line boot parameter passed to the panic-ed
2066 kernel. Please take a look at Documentation/kdump/kdump.txt
2067 for more details about crash dumps.
2069 Usage of bzImage for capturing the crash dump is recommended as
2070 one does not have to build two kernels. Same kernel can be used
2071 as production kernel and capture kernel. Above option should have
2072 gone away after relocatable bzImage support is introduced. But it
2073 is present because there are users out there who continue to use
2074 vmlinux for dump capture. This option should go away down the
2077 Don't change this unless you know what you are doing.
2080 bool "Build a relocatable kernel"
2083 This builds a kernel image that retains relocation information
2084 so it can be loaded someplace besides the default 1MB.
2085 The relocations tend to make the kernel binary about 10% larger,
2086 but are discarded at runtime.
2088 One use is for the kexec on panic case where the recovery kernel
2089 must live at a different physical address than the primary
2092 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2093 it has been loaded at and the compile time physical address
2094 (CONFIG_PHYSICAL_START) is used as the minimum location.
2096 config RANDOMIZE_BASE
2097 bool "Randomize the address of the kernel image (KASLR)"
2098 depends on RELOCATABLE
2101 In support of Kernel Address Space Layout Randomization (KASLR),
2102 this randomizes the physical address at which the kernel image
2103 is decompressed and the virtual address where the kernel
2104 image is mapped, as a security feature that deters exploit
2105 attempts relying on knowledge of the location of kernel
2108 On 64-bit, the kernel physical and virtual addresses are
2109 randomized separately. The physical address will be anywhere
2110 between 16MB and the top of physical memory (up to 64TB). The
2111 virtual address will be randomized from 16MB up to 1GB (9 bits
2112 of entropy). Note that this also reduces the memory space
2113 available to kernel modules from 1.5GB to 1GB.
2115 On 32-bit, the kernel physical and virtual addresses are
2116 randomized together. They will be randomized from 16MB up to
2117 512MB (8 bits of entropy).
2119 Entropy is generated using the RDRAND instruction if it is
2120 supported. If RDTSC is supported, its value is mixed into
2121 the entropy pool as well. If neither RDRAND nor RDTSC are
2122 supported, then entropy is read from the i8254 timer. The
2123 usable entropy is limited by the kernel being built using
2124 2GB addressing, and that PHYSICAL_ALIGN must be at a
2125 minimum of 2MB. As a result, only 10 bits of entropy are
2126 theoretically possible, but the implementations are further
2127 limited due to memory layouts.
2131 # Relocation on x86 needs some additional build support
2132 config X86_NEED_RELOCS
2134 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2136 config PHYSICAL_ALIGN
2137 hex "Alignment value to which kernel should be aligned"
2139 range 0x2000 0x1000000 if X86_32
2140 range 0x200000 0x1000000 if X86_64
2142 This value puts the alignment restrictions on physical address
2143 where kernel is loaded and run from. Kernel is compiled for an
2144 address which meets above alignment restriction.
2146 If bootloader loads the kernel at a non-aligned address and
2147 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2148 address aligned to above value and run from there.
2150 If bootloader loads the kernel at a non-aligned address and
2151 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2152 load address and decompress itself to the address it has been
2153 compiled for and run from there. The address for which kernel is
2154 compiled already meets above alignment restrictions. Hence the
2155 end result is that kernel runs from a physical address meeting
2156 above alignment restrictions.
2158 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2159 this value must be a multiple of 0x200000.
2161 Don't change this unless you know what you are doing.
2163 config DYNAMIC_MEMORY_LAYOUT
2166 This option makes base addresses of vmalloc and vmemmap as well as
2167 __PAGE_OFFSET movable during boot.
2169 config RANDOMIZE_MEMORY
2170 bool "Randomize the kernel memory sections"
2172 depends on RANDOMIZE_BASE
2173 select DYNAMIC_MEMORY_LAYOUT
2174 default RANDOMIZE_BASE
2176 Randomizes the base virtual address of kernel memory sections
2177 (physical memory mapping, vmalloc & vmemmap). This security feature
2178 makes exploits relying on predictable memory locations less reliable.
2180 The order of allocations remains unchanged. Entropy is generated in
2181 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2182 configuration have in average 30,000 different possible virtual
2183 addresses for each memory section.
2187 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2188 hex "Physical memory mapping padding" if EXPERT
2189 depends on RANDOMIZE_MEMORY
2190 default "0xa" if MEMORY_HOTPLUG
2192 range 0x1 0x40 if MEMORY_HOTPLUG
2195 Define the padding in terabytes added to the existing physical
2196 memory size during kernel memory randomization. It is useful
2197 for memory hotplug support but reduces the entropy available for
2198 address randomization.
2200 If unsure, leave at the default value.
2206 config BOOTPARAM_HOTPLUG_CPU0
2207 bool "Set default setting of cpu0_hotpluggable"
2208 depends on HOTPLUG_CPU
2210 Set whether default state of cpu0_hotpluggable is on or off.
2212 Say Y here to enable CPU0 hotplug by default. If this switch
2213 is turned on, there is no need to give cpu0_hotplug kernel
2214 parameter and the CPU0 hotplug feature is enabled by default.
2216 Please note: there are two known CPU0 dependencies if you want
2217 to enable the CPU0 hotplug feature either by this switch or by
2218 cpu0_hotplug kernel parameter.
2220 First, resume from hibernate or suspend always starts from CPU0.
2221 So hibernate and suspend are prevented if CPU0 is offline.
2223 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2224 offline if any interrupt can not migrate out of CPU0. There may
2225 be other CPU0 dependencies.
2227 Please make sure the dependencies are under your control before
2228 you enable this feature.
2230 Say N if you don't want to enable CPU0 hotplug feature by default.
2231 You still can enable the CPU0 hotplug feature at boot by kernel
2232 parameter cpu0_hotplug.
2234 config DEBUG_HOTPLUG_CPU0
2236 prompt "Debug CPU0 hotplug"
2237 depends on HOTPLUG_CPU
2239 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2240 soon as possible and boots up userspace with CPU0 offlined. User
2241 can online CPU0 back after boot time.
2243 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2244 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2245 compilation or giving cpu0_hotplug kernel parameter at boot.
2251 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2252 depends on COMPAT_32
2254 Certain buggy versions of glibc will crash if they are
2255 presented with a 32-bit vDSO that is not mapped at the address
2256 indicated in its segment table.
2258 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2259 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2260 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2261 the only released version with the bug, but OpenSUSE 9
2262 contains a buggy "glibc 2.3.2".
2264 The symptom of the bug is that everything crashes on startup, saying:
2265 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2267 Saying Y here changes the default value of the vdso32 boot
2268 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2269 This works around the glibc bug but hurts performance.
2271 If unsure, say N: if you are compiling your own kernel, you
2272 are unlikely to be using a buggy version of glibc.
2275 prompt "vsyscall table for legacy applications"
2277 default LEGACY_VSYSCALL_EMULATE
2279 Legacy user code that does not know how to find the vDSO expects
2280 to be able to issue three syscalls by calling fixed addresses in
2281 kernel space. Since this location is not randomized with ASLR,
2282 it can be used to assist security vulnerability exploitation.
2284 This setting can be changed at boot time via the kernel command
2285 line parameter vsyscall=[emulate|none].
2287 On a system with recent enough glibc (2.14 or newer) and no
2288 static binaries, you can say None without a performance penalty
2289 to improve security.
2291 If unsure, select "Emulate".
2293 config LEGACY_VSYSCALL_EMULATE
2296 The kernel traps and emulates calls into the fixed
2297 vsyscall address mapping. This makes the mapping
2298 non-executable, but it still contains known contents,
2299 which could be used in certain rare security vulnerability
2300 exploits. This configuration is recommended when userspace
2301 still uses the vsyscall area.
2303 config LEGACY_VSYSCALL_NONE
2306 There will be no vsyscall mapping at all. This will
2307 eliminate any risk of ASLR bypass due to the vsyscall
2308 fixed address mapping. Attempts to use the vsyscalls
2309 will be reported to dmesg, so that either old or
2310 malicious userspace programs can be identified.
2315 bool "Built-in kernel command line"
2317 Allow for specifying boot arguments to the kernel at
2318 build time. On some systems (e.g. embedded ones), it is
2319 necessary or convenient to provide some or all of the
2320 kernel boot arguments with the kernel itself (that is,
2321 to not rely on the boot loader to provide them.)
2323 To compile command line arguments into the kernel,
2324 set this option to 'Y', then fill in the
2325 boot arguments in CONFIG_CMDLINE.
2327 Systems with fully functional boot loaders (i.e. non-embedded)
2328 should leave this option set to 'N'.
2331 string "Built-in kernel command string"
2332 depends on CMDLINE_BOOL
2335 Enter arguments here that should be compiled into the kernel
2336 image and used at boot time. If the boot loader provides a
2337 command line at boot time, it is appended to this string to
2338 form the full kernel command line, when the system boots.
2340 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2341 change this behavior.
2343 In most cases, the command line (whether built-in or provided
2344 by the boot loader) should specify the device for the root
2347 config CMDLINE_OVERRIDE
2348 bool "Built-in command line overrides boot loader arguments"
2349 depends on CMDLINE_BOOL
2351 Set this option to 'Y' to have the kernel ignore the boot loader
2352 command line, and use ONLY the built-in command line.
2354 This is used to work around broken boot loaders. This should
2355 be set to 'N' under normal conditions.
2357 config MODIFY_LDT_SYSCALL
2358 bool "Enable the LDT (local descriptor table)" if EXPERT
2361 Linux can allow user programs to install a per-process x86
2362 Local Descriptor Table (LDT) using the modify_ldt(2) system
2363 call. This is required to run 16-bit or segmented code such as
2364 DOSEMU or some Wine programs. It is also used by some very old
2365 threading libraries.
2367 Enabling this feature adds a small amount of overhead to
2368 context switches and increases the low-level kernel attack
2369 surface. Disabling it removes the modify_ldt(2) system call.
2371 Saying 'N' here may make sense for embedded or server kernels.
2373 source "kernel/livepatch/Kconfig"
2377 config ARCH_HAS_ADD_PAGES
2379 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2381 config ARCH_ENABLE_MEMORY_HOTPLUG
2383 depends on X86_64 || (X86_32 && HIGHMEM)
2385 config ARCH_ENABLE_MEMORY_HOTREMOVE
2387 depends on MEMORY_HOTPLUG
2389 config USE_PERCPU_NUMA_NODE_ID
2393 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2395 depends on X86_64 || X86_PAE
2397 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2399 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2401 config ARCH_ENABLE_THP_MIGRATION
2403 depends on X86_64 && TRANSPARENT_HUGEPAGE
2405 menu "Power management and ACPI options"
2407 config ARCH_HIBERNATION_HEADER
2409 depends on HIBERNATION
2411 source "kernel/power/Kconfig"
2413 source "drivers/acpi/Kconfig"
2415 source "drivers/sfi/Kconfig"
2422 tristate "APM (Advanced Power Management) BIOS support"
2423 depends on X86_32 && PM_SLEEP
2425 APM is a BIOS specification for saving power using several different
2426 techniques. This is mostly useful for battery powered laptops with
2427 APM compliant BIOSes. If you say Y here, the system time will be
2428 reset after a RESUME operation, the /proc/apm device will provide
2429 battery status information, and user-space programs will receive
2430 notification of APM "events" (e.g. battery status change).
2432 If you select "Y" here, you can disable actual use of the APM
2433 BIOS by passing the "apm=off" option to the kernel at boot time.
2435 Note that the APM support is almost completely disabled for
2436 machines with more than one CPU.
2438 In order to use APM, you will need supporting software. For location
2439 and more information, read <file:Documentation/power/apm-acpi.txt>
2440 and the Battery Powered Linux mini-HOWTO, available from
2441 <http://www.tldp.org/docs.html#howto>.
2443 This driver does not spin down disk drives (see the hdparm(8)
2444 manpage ("man 8 hdparm") for that), and it doesn't turn off
2445 VESA-compliant "green" monitors.
2447 This driver does not support the TI 4000M TravelMate and the ACER
2448 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2449 desktop machines also don't have compliant BIOSes, and this driver
2450 may cause those machines to panic during the boot phase.
2452 Generally, if you don't have a battery in your machine, there isn't
2453 much point in using this driver and you should say N. If you get
2454 random kernel OOPSes or reboots that don't seem to be related to
2455 anything, try disabling/enabling this option (or disabling/enabling
2458 Some other things you should try when experiencing seemingly random,
2461 1) make sure that you have enough swap space and that it is
2463 2) pass the "no-hlt" option to the kernel
2464 3) switch on floating point emulation in the kernel and pass
2465 the "no387" option to the kernel
2466 4) pass the "floppy=nodma" option to the kernel
2467 5) pass the "mem=4M" option to the kernel (thereby disabling
2468 all but the first 4 MB of RAM)
2469 6) make sure that the CPU is not over clocked.
2470 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2471 8) disable the cache from your BIOS settings
2472 9) install a fan for the video card or exchange video RAM
2473 10) install a better fan for the CPU
2474 11) exchange RAM chips
2475 12) exchange the motherboard.
2477 To compile this driver as a module, choose M here: the
2478 module will be called apm.
2482 config APM_IGNORE_USER_SUSPEND
2483 bool "Ignore USER SUSPEND"
2485 This option will ignore USER SUSPEND requests. On machines with a
2486 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2487 series notebooks, it is necessary to say Y because of a BIOS bug.
2489 config APM_DO_ENABLE
2490 bool "Enable PM at boot time"
2492 Enable APM features at boot time. From page 36 of the APM BIOS
2493 specification: "When disabled, the APM BIOS does not automatically
2494 power manage devices, enter the Standby State, enter the Suspend
2495 State, or take power saving steps in response to CPU Idle calls."
2496 This driver will make CPU Idle calls when Linux is idle (unless this
2497 feature is turned off -- see "Do CPU IDLE calls", below). This
2498 should always save battery power, but more complicated APM features
2499 will be dependent on your BIOS implementation. You may need to turn
2500 this option off if your computer hangs at boot time when using APM
2501 support, or if it beeps continuously instead of suspending. Turn
2502 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2503 T400CDT. This is off by default since most machines do fine without
2508 bool "Make CPU Idle calls when idle"
2510 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2511 On some machines, this can activate improved power savings, such as
2512 a slowed CPU clock rate, when the machine is idle. These idle calls
2513 are made after the idle loop has run for some length of time (e.g.,
2514 333 mS). On some machines, this will cause a hang at boot time or
2515 whenever the CPU becomes idle. (On machines with more than one CPU,
2516 this option does nothing.)
2518 config APM_DISPLAY_BLANK
2519 bool "Enable console blanking using APM"
2521 Enable console blanking using the APM. Some laptops can use this to
2522 turn off the LCD backlight when the screen blanker of the Linux
2523 virtual console blanks the screen. Note that this is only used by
2524 the virtual console screen blanker, and won't turn off the backlight
2525 when using the X Window system. This also doesn't have anything to
2526 do with your VESA-compliant power-saving monitor. Further, this
2527 option doesn't work for all laptops -- it might not turn off your
2528 backlight at all, or it might print a lot of errors to the console,
2529 especially if you are using gpm.
2531 config APM_ALLOW_INTS
2532 bool "Allow interrupts during APM BIOS calls"
2534 Normally we disable external interrupts while we are making calls to
2535 the APM BIOS as a measure to lessen the effects of a badly behaving
2536 BIOS implementation. The BIOS should reenable interrupts if it
2537 needs to. Unfortunately, some BIOSes do not -- especially those in
2538 many of the newer IBM Thinkpads. If you experience hangs when you
2539 suspend, try setting this to Y. Otherwise, say N.
2543 source "drivers/cpufreq/Kconfig"
2545 source "drivers/cpuidle/Kconfig"
2547 source "drivers/idle/Kconfig"
2552 menu "Bus options (PCI etc.)"
2555 prompt "PCI access mode"
2556 depends on X86_32 && PCI
2559 On PCI systems, the BIOS can be used to detect the PCI devices and
2560 determine their configuration. However, some old PCI motherboards
2561 have BIOS bugs and may crash if this is done. Also, some embedded
2562 PCI-based systems don't have any BIOS at all. Linux can also try to
2563 detect the PCI hardware directly without using the BIOS.
2565 With this option, you can specify how Linux should detect the
2566 PCI devices. If you choose "BIOS", the BIOS will be used,
2567 if you choose "Direct", the BIOS won't be used, and if you
2568 choose "MMConfig", then PCI Express MMCONFIG will be used.
2569 If you choose "Any", the kernel will try MMCONFIG, then the
2570 direct access method and falls back to the BIOS if that doesn't
2571 work. If unsure, go with the default, which is "Any".
2576 config PCI_GOMMCONFIG
2593 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2595 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2598 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2601 bool "Support mmconfig PCI config space access" if X86_64
2603 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2604 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2608 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2612 depends on PCI && XEN
2615 config MMCONF_FAM10H
2617 depends on X86_64 && PCI_MMCONFIG && ACPI
2619 config PCI_CNB20LE_QUIRK
2620 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2623 Read the PCI windows out of the CNB20LE host bridge. This allows
2624 PCI hotplug to work on systems with the CNB20LE chipset which do
2627 There's no public spec for this chipset, and this functionality
2628 is known to be incomplete.
2630 You should say N unless you know you need this.
2633 bool "ISA bus support on modern systems" if EXPERT
2635 Expose ISA bus device drivers and options available for selection and
2636 configuration. Enable this option if your target machine has an ISA
2637 bus. ISA is an older system, displaced by PCI and newer bus
2638 architectures -- if your target machine is modern, it probably does
2639 not have an ISA bus.
2643 # x86_64 have no ISA slots, but can have ISA-style DMA.
2645 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2648 Enables ISA-style DMA support for devices requiring such controllers.
2656 Find out whether you have ISA slots on your motherboard. ISA is the
2657 name of a bus system, i.e. the way the CPU talks to the other stuff
2658 inside your box. Other bus systems are PCI, EISA, MicroChannel
2659 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2660 newer boards don't support it. If you have ISA, say Y, otherwise N.
2663 tristate "NatSemi SCx200 support"
2665 This provides basic support for National Semiconductor's
2666 (now AMD's) Geode processors. The driver probes for the
2667 PCI-IDs of several on-chip devices, so its a good dependency
2668 for other scx200_* drivers.
2670 If compiled as a module, the driver is named scx200.
2672 config SCx200HR_TIMER
2673 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2677 This driver provides a clocksource built upon the on-chip
2678 27MHz high-resolution timer. Its also a workaround for
2679 NSC Geode SC-1100's buggy TSC, which loses time when the
2680 processor goes idle (as is done by the scheduler). The
2681 other workaround is idle=poll boot option.
2684 bool "One Laptop Per Child support"
2691 Add support for detecting the unique features of the OLPC
2695 bool "OLPC XO-1 Power Management"
2696 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2698 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2701 bool "OLPC XO-1 Real Time Clock"
2702 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2704 Add support for the XO-1 real time clock, which can be used as a
2705 programmable wakeup source.
2708 bool "OLPC XO-1 SCI extras"
2709 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2713 Add support for SCI-based features of the OLPC XO-1 laptop:
2714 - EC-driven system wakeups
2718 - AC adapter status updates
2719 - Battery status updates
2721 config OLPC_XO15_SCI
2722 bool "OLPC XO-1.5 SCI extras"
2723 depends on OLPC && ACPI
2726 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2727 - EC-driven system wakeups
2728 - AC adapter status updates
2729 - Battery status updates
2732 bool "PCEngines ALIX System Support (LED setup)"
2735 This option enables system support for the PCEngines ALIX.
2736 At present this just sets up LEDs for GPIO control on
2737 ALIX2/3/6 boards. However, other system specific setup should
2740 Note: You must still enable the drivers for GPIO and LED support
2741 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2743 Note: You have to set alix.force=1 for boards with Award BIOS.
2746 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2749 This option enables system support for the Soekris Engineering net5501.
2752 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2756 This option enables system support for the Traverse Technologies GEOS.
2759 bool "Technologic Systems TS-5500 platform support"
2761 select CHECK_SIGNATURE
2765 This option enables system support for the Technologic Systems TS-5500.
2771 depends on CPU_SUP_AMD && PCI
2774 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2776 Firmwares often provide initial graphics framebuffers so the BIOS,
2777 bootloader or kernel can show basic video-output during boot for
2778 user-guidance and debugging. Historically, x86 used the VESA BIOS
2779 Extensions and EFI-framebuffers for this, which are mostly limited
2781 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2782 framebuffers so the new generic system-framebuffer drivers can be
2783 used on x86. If the framebuffer is not compatible with the generic
2784 modes, it is advertised as fallback platform framebuffer so legacy
2785 drivers like efifb, vesafb and uvesafb can pick it up.
2786 If this option is not selected, all system framebuffers are always
2787 marked as fallback platform framebuffers as usual.
2789 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2790 not be able to pick up generic system framebuffers if this option
2791 is selected. You are highly encouraged to enable simplefb as
2792 replacement if you select this option. simplefb can correctly deal
2793 with generic system framebuffers. But you should still keep vesafb
2794 and others enabled as fallback if a system framebuffer is
2795 incompatible with simplefb.
2802 menu "Binary Emulations"
2804 config IA32_EMULATION
2805 bool "IA32 Emulation"
2807 select ARCH_WANT_OLD_COMPAT_IPC
2809 select COMPAT_BINFMT_ELF
2810 select COMPAT_OLD_SIGACTION
2812 Include code to run legacy 32-bit programs under a
2813 64-bit kernel. You should likely turn this on, unless you're
2814 100% sure that you don't have any 32-bit programs left.
2817 tristate "IA32 a.out support"
2818 depends on IA32_EMULATION
2821 Support old a.out binaries in the 32bit emulation.
2824 bool "x32 ABI for 64-bit mode"
2827 Include code to run binaries for the x32 native 32-bit ABI
2828 for 64-bit processors. An x32 process gets access to the
2829 full 64-bit register file and wide data path while leaving
2830 pointers at 32 bits for smaller memory footprint.
2832 You will need a recent binutils (2.22 or later) with
2833 elf32_x86_64 support enabled to compile a kernel with this
2838 depends on IA32_EMULATION || X86_32
2840 select OLD_SIGSUSPEND3
2844 depends on IA32_EMULATION || X86_X32
2847 config COMPAT_FOR_U64_ALIGNMENT
2850 config SYSVIPC_COMPAT
2858 config HAVE_ATOMIC_IOMAP
2862 config X86_DEV_DMA_OPS
2865 config HAVE_GENERIC_GUP
2868 source "drivers/firmware/Kconfig"
2870 source "arch/x86/kvm/Kconfig"