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 if (MEMORY_ISOLATION && COMPACTION) || CMA
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_DISCARD_MEMBLOCK
51 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
52 select ARCH_HAS_DEBUG_VIRTUAL
53 select ARCH_HAS_DEVMEM_IS_ALLOWED
54 select ARCH_HAS_ELF_RANDOMIZE
55 select ARCH_HAS_FAST_MULTIPLIER
56 select ARCH_HAS_FILTER_PGPROT
57 select ARCH_HAS_FORTIFY_SOURCE
58 select ARCH_HAS_GCOV_PROFILE_ALL
59 select ARCH_HAS_KCOV if X86_64
60 select ARCH_HAS_MEMBARRIER_SYNC_CORE
61 select ARCH_HAS_PMEM_API if X86_64
62 select ARCH_HAS_PTE_SPECIAL
63 select ARCH_HAS_REFCOUNT
64 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
65 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
66 select ARCH_HAS_SET_MEMORY
67 select ARCH_HAS_SET_DIRECT_MAP
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
78 select ARCH_SUPPORTS_ACPI
79 select ARCH_SUPPORTS_ATOMIC_RMW
80 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
81 select ARCH_USE_BUILTIN_BSWAP
82 select ARCH_USE_QUEUED_RWLOCKS
83 select ARCH_USE_QUEUED_SPINLOCKS
84 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
85 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
86 select ARCH_WANTS_THP_SWAP if X86_64
87 select BUILDTIME_EXTABLE_SORT
89 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
90 select CLOCKSOURCE_WATCHDOG
91 select DCACHE_WORD_ACCESS
92 select EDAC_ATOMIC_SCRUB
94 select GENERIC_CLOCKEVENTS
95 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
96 select GENERIC_CLOCKEVENTS_MIN_ADJUST
97 select GENERIC_CMOS_UPDATE
98 select GENERIC_CPU_AUTOPROBE
99 select GENERIC_CPU_VULNERABILITIES
100 select GENERIC_EARLY_IOREMAP
101 select GENERIC_FIND_FIRST_BIT
103 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
104 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
105 select GENERIC_IRQ_MIGRATION if SMP
106 select GENERIC_IRQ_PROBE
107 select GENERIC_IRQ_RESERVATION_MODE
108 select GENERIC_IRQ_SHOW
109 select GENERIC_PENDING_IRQ if SMP
110 select GENERIC_SMP_IDLE_THREAD
111 select GENERIC_STRNCPY_FROM_USER
112 select GENERIC_STRNLEN_USER
113 select GENERIC_TIME_VSYSCALL
114 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
115 select HAVE_ACPI_APEI if ACPI
116 select HAVE_ACPI_APEI_NMI if ACPI
117 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
118 select HAVE_ARCH_AUDITSYSCALL
119 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
120 select HAVE_ARCH_JUMP_LABEL
121 select HAVE_ARCH_JUMP_LABEL_RELATIVE
122 select HAVE_ARCH_KASAN if X86_64
123 select HAVE_ARCH_KGDB
124 select HAVE_ARCH_MMAP_RND_BITS if MMU
125 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
126 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
127 select HAVE_ARCH_PREL32_RELOCATIONS
128 select HAVE_ARCH_SECCOMP_FILTER
129 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
130 select HAVE_ARCH_STACKLEAK
131 select HAVE_ARCH_TRACEHOOK
132 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
133 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
134 select HAVE_ARCH_VMAP_STACK if X86_64
135 select HAVE_ARCH_WITHIN_STACK_FRAMES
136 select HAVE_CMPXCHG_DOUBLE
137 select HAVE_CMPXCHG_LOCAL
138 select HAVE_CONTEXT_TRACKING if X86_64
139 select HAVE_COPY_THREAD_TLS
140 select HAVE_C_RECORDMCOUNT
141 select HAVE_DEBUG_KMEMLEAK
142 select HAVE_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_REGS_AND_STACK_ACCESS_API
187 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
188 select HAVE_FUNCTION_ARG_ACCESS_API
189 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
190 select HAVE_STACK_VALIDATION if X86_64
192 select HAVE_SYSCALL_TRACEPOINTS
193 select HAVE_UNSTABLE_SCHED_CLOCK
194 select HAVE_USER_RETURN_NOTIFIER
195 select HOTPLUG_SMT if SMP
196 select IRQ_FORCED_THREADING
197 select NEED_SG_DMA_LENGTH
198 select PCI_DOMAINS if PCI
199 select PCI_LOCKLESS_CONFIG if PCI
202 select RTC_MC146818_LIB
205 select SYSCTL_EXCEPTION_TRACE
206 select THREAD_INFO_IN_TASK
207 select USER_STACKTRACE_SUPPORT
209 select X86_FEATURE_NAMES if PROC_FS
211 config INSTRUCTION_DECODER
213 depends on KPROBES || PERF_EVENTS || UPROBES
217 default "elf32-i386" if X86_32
218 default "elf64-x86-64" if X86_64
220 config ARCH_DEFCONFIG
222 default "arch/x86/configs/i386_defconfig" if X86_32
223 default "arch/x86/configs/x86_64_defconfig" if X86_64
225 config LOCKDEP_SUPPORT
228 config STACKTRACE_SUPPORT
234 config ARCH_MMAP_RND_BITS_MIN
238 config ARCH_MMAP_RND_BITS_MAX
242 config ARCH_MMAP_RND_COMPAT_BITS_MIN
245 config ARCH_MMAP_RND_COMPAT_BITS_MAX
251 config GENERIC_ISA_DMA
253 depends on ISA_DMA_API
258 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
260 config GENERIC_BUG_RELATIVE_POINTERS
263 config GENERIC_HWEIGHT
266 config ARCH_MAY_HAVE_PC_FDC
268 depends on ISA_DMA_API
270 config GENERIC_CALIBRATE_DELAY
273 config ARCH_HAS_CPU_RELAX
276 config ARCH_HAS_CACHE_LINE_SIZE
279 config ARCH_HAS_FILTER_PGPROT
282 config HAVE_SETUP_PER_CPU_AREA
285 config NEED_PER_CPU_EMBED_FIRST_CHUNK
288 config NEED_PER_CPU_PAGE_FIRST_CHUNK
291 config ARCH_HIBERNATION_POSSIBLE
294 config ARCH_SUSPEND_POSSIBLE
297 config ARCH_WANT_HUGE_PMD_SHARE
300 config ARCH_WANT_GENERAL_HUGETLB
309 config ARCH_SUPPORTS_OPTIMIZED_INLINING
312 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
315 config KASAN_SHADOW_OFFSET
318 default 0xdffffc0000000000
320 config HAVE_INTEL_TXT
322 depends on INTEL_IOMMU && ACPI
326 depends on X86_32 && SMP
330 depends on X86_64 && SMP
332 config X86_32_LAZY_GS
334 depends on X86_32 && !STACKPROTECTOR
336 config ARCH_SUPPORTS_UPROBES
339 config FIX_EARLYCON_MEM
342 config DYNAMIC_PHYSICAL_MASK
345 config PGTABLE_LEVELS
347 default 5 if X86_5LEVEL
352 config CC_HAS_SANE_STACKPROTECTOR
354 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
355 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
357 We have to make sure stack protector is unconditionally disabled if
358 the compiler produces broken code.
360 menu "Processor type and features"
363 bool "DMA memory allocation support" if EXPERT
366 DMA memory allocation support allows devices with less than 32-bit
367 addressing to allocate within the first 16MB of address space.
368 Disable if no such devices will be used.
373 bool "Symmetric multi-processing support"
375 This enables support for systems with more than one CPU. If you have
376 a system with only one CPU, say N. If you have a system with more
379 If you say N here, the kernel will run on uni- and multiprocessor
380 machines, but will use only one CPU of a multiprocessor machine. If
381 you say Y here, the kernel will run on many, but not all,
382 uniprocessor machines. On a uniprocessor machine, the kernel
383 will run faster if you say N here.
385 Note that if you say Y here and choose architecture "586" or
386 "Pentium" under "Processor family", the kernel will not work on 486
387 architectures. Similarly, multiprocessor kernels for the "PPro"
388 architecture may not work on all Pentium based boards.
390 People using multiprocessor machines who say Y here should also say
391 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
392 Management" code will be disabled if you say Y here.
394 See also <file:Documentation/x86/i386/IO-APIC.txt>,
395 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
396 <http://www.tldp.org/docs.html#howto>.
398 If you don't know what to do here, say N.
400 config X86_FEATURE_NAMES
401 bool "Processor feature human-readable names" if EMBEDDED
404 This option compiles in a table of x86 feature bits and corresponding
405 names. This is required to support /proc/cpuinfo and a few kernel
406 messages. You can disable this to save space, at the expense of
407 making those few kernel messages show numeric feature bits instead.
412 bool "Support x2apic"
413 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
415 This enables x2apic support on CPUs that have this feature.
417 This allows 32-bit apic IDs (so it can support very large systems),
418 and accesses the local apic via MSRs not via mmio.
420 If you don't know what to do here, say N.
423 bool "Enable MPS table" if ACPI || SFI
425 depends on X86_LOCAL_APIC
427 For old smp systems that do not have proper acpi support. Newer systems
428 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
432 depends on X86_GOLDFISH
435 bool "Avoid speculative indirect branches in kernel"
437 select STACK_VALIDATION if HAVE_STACK_VALIDATION
439 Compile kernel with the retpoline compiler options to guard against
440 kernel-to-user data leaks by avoiding speculative indirect
441 branches. Requires a compiler with -mindirect-branch=thunk-extern
442 support for full protection. The kernel may run slower.
444 config X86_CPU_RESCTRL
445 bool "x86 CPU resource control support"
446 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
449 Enable x86 CPU resource control support.
451 Provide support for the allocation and monitoring of system resources
454 Intel calls this Intel Resource Director Technology
455 (Intel(R) RDT). More information about RDT can be found in the
456 Intel x86 Architecture Software Developer Manual.
458 AMD calls this AMD Platform Quality of Service (AMD QoS).
459 More information about AMD QoS can be found in the AMD64 Technology
460 Platform Quality of Service Extensions manual.
466 bool "Support for big SMP systems with more than 8 CPUs"
469 This option is needed for the systems that have more than 8 CPUs
471 config X86_EXTENDED_PLATFORM
472 bool "Support for extended (non-PC) x86 platforms"
475 If you disable this option then the kernel will only support
476 standard PC platforms. (which covers the vast majority of
479 If you enable this option then you'll be able to select support
480 for the following (non-PC) 32 bit x86 platforms:
481 Goldfish (Android emulator)
484 SGI 320/540 (Visual Workstation)
485 STA2X11-based (e.g. Northville)
486 Moorestown MID devices
488 If you have one of these systems, or if you want to build a
489 generic distribution kernel, say Y here - otherwise say N.
493 config X86_EXTENDED_PLATFORM
494 bool "Support for extended (non-PC) x86 platforms"
497 If you disable this option then the kernel will only support
498 standard PC platforms. (which covers the vast majority of
501 If you enable this option then you'll be able to select support
502 for the following (non-PC) 64 bit x86 platforms:
507 If you have one of these systems, or if you want to build a
508 generic distribution kernel, say Y here - otherwise say N.
510 # This is an alphabetically sorted list of 64 bit extended platforms
511 # Please maintain the alphabetic order if and when there are additions
513 bool "Numascale NumaChip"
515 depends on X86_EXTENDED_PLATFORM
518 depends on X86_X2APIC
519 depends on PCI_MMCONFIG
521 Adds support for Numascale NumaChip large-SMP systems. Needed to
522 enable more than ~168 cores.
523 If you don't have one of these, you should say N here.
527 select HYPERVISOR_GUEST
529 depends on X86_64 && PCI
530 depends on X86_EXTENDED_PLATFORM
533 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
534 supposed to run on these EM64T-based machines. Only choose this option
535 if you have one of these machines.
538 bool "SGI Ultraviolet"
540 depends on X86_EXTENDED_PLATFORM
543 depends on X86_X2APIC
546 This option is needed in order to support SGI Ultraviolet systems.
547 If you don't have one of these, you should say N here.
549 # Following is an alphabetically sorted list of 32 bit extended platforms
550 # Please maintain the alphabetic order if and when there are additions
553 bool "Goldfish (Virtual Platform)"
554 depends on X86_EXTENDED_PLATFORM
556 Enable support for the Goldfish virtual platform used primarily
557 for Android development. Unless you are building for the Android
558 Goldfish emulator say N here.
561 bool "CE4100 TV platform"
563 depends on PCI_GODIRECT
564 depends on X86_IO_APIC
566 depends on X86_EXTENDED_PLATFORM
567 select X86_REBOOTFIXUPS
569 select OF_EARLY_FLATTREE
571 Select for the Intel CE media processor (CE4100) SOC.
572 This option compiles in support for the CE4100 SOC for settop
573 boxes and media devices.
576 bool "Intel MID platform support"
577 depends on X86_EXTENDED_PLATFORM
578 depends on X86_PLATFORM_DEVICES
580 depends on X86_64 || (PCI_GOANY && X86_32)
581 depends on X86_IO_APIC
587 select MFD_INTEL_MSIC
589 Select to build a kernel capable of supporting Intel MID (Mobile
590 Internet Device) platform systems which do not have the PCI legacy
591 interfaces. If you are building for a PC class system say N here.
593 Intel MID platforms are based on an Intel processor and chipset which
594 consume less power than most of the x86 derivatives.
596 config X86_INTEL_QUARK
597 bool "Intel Quark platform support"
599 depends on X86_EXTENDED_PLATFORM
600 depends on X86_PLATFORM_DEVICES
604 depends on X86_IO_APIC
609 Select to include support for Quark X1000 SoC.
610 Say Y here if you have a Quark based system such as the Arduino
611 compatible Intel Galileo.
613 config X86_INTEL_LPSS
614 bool "Intel Low Power Subsystem Support"
615 depends on X86 && ACPI && PCI
620 Select to build support for Intel Low Power Subsystem such as
621 found on Intel Lynxpoint PCH. Selecting this option enables
622 things like clock tree (common clock framework) and pincontrol
623 which are needed by the LPSS peripheral drivers.
625 config X86_AMD_PLATFORM_DEVICE
626 bool "AMD ACPI2Platform devices support"
631 Select to interpret AMD specific ACPI device to platform device
632 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
633 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
634 implemented under PINCTRL subsystem.
637 tristate "Intel SoC IOSF Sideband support for SoC platforms"
640 This option enables sideband register access support for Intel SoC
641 platforms. On these platforms the IOSF sideband is used in lieu of
642 MSR's for some register accesses, mostly but not limited to thermal
643 and power. Drivers may query the availability of this device to
644 determine if they need the sideband in order to work on these
645 platforms. The sideband is available on the following SoC products.
646 This list is not meant to be exclusive.
651 You should say Y if you are running a kernel on one of these SoC's.
653 config IOSF_MBI_DEBUG
654 bool "Enable IOSF sideband access through debugfs"
655 depends on IOSF_MBI && DEBUG_FS
657 Select this option to expose the IOSF sideband access registers (MCR,
658 MDR, MCRX) through debugfs to write and read register information from
659 different units on the SoC. This is most useful for obtaining device
660 state information for debug and analysis. As this is a general access
661 mechanism, users of this option would have specific knowledge of the
662 device they want to access.
664 If you don't require the option or are in doubt, say N.
667 bool "RDC R-321x SoC"
669 depends on X86_EXTENDED_PLATFORM
671 select X86_REBOOTFIXUPS
673 This option is needed for RDC R-321x system-on-chip, also known
675 If you don't have one of these chips, you should say N here.
677 config X86_32_NON_STANDARD
678 bool "Support non-standard 32-bit SMP architectures"
679 depends on X86_32 && SMP
680 depends on X86_EXTENDED_PLATFORM
682 This option compiles in the bigsmp and STA2X11 default
683 subarchitectures. It is intended for a generic binary
684 kernel. If you select them all, kernel will probe it one by
685 one and will fallback to default.
687 # Alphabetically sorted list of Non standard 32 bit platforms
689 config X86_SUPPORTS_MEMORY_FAILURE
691 # MCE code calls memory_failure():
693 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
694 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
695 depends on X86_64 || !SPARSEMEM
696 select ARCH_SUPPORTS_MEMORY_FAILURE
699 bool "STA2X11 Companion Chip Support"
700 depends on X86_32_NON_STANDARD && PCI
701 select ARCH_HAS_PHYS_TO_DMA
706 This adds support for boards based on the STA2X11 IO-Hub,
707 a.k.a. "ConneXt". The chip is used in place of the standard
708 PC chipset, so all "standard" peripherals are missing. If this
709 option is selected the kernel will still be able to boot on
710 standard PC machines.
713 tristate "Eurobraille/Iris poweroff module"
716 The Iris machines from EuroBraille do not have APM or ACPI support
717 to shut themselves down properly. A special I/O sequence is
718 needed to do so, which is what this module does at
721 This is only for Iris machines from EuroBraille.
725 config SCHED_OMIT_FRAME_POINTER
727 prompt "Single-depth WCHAN output"
730 Calculate simpler /proc/<PID>/wchan values. If this option
731 is disabled then wchan values will recurse back to the
732 caller function. This provides more accurate wchan values,
733 at the expense of slightly more scheduling overhead.
735 If in doubt, say "Y".
737 menuconfig HYPERVISOR_GUEST
738 bool "Linux guest support"
740 Say Y here to enable options for running Linux under various hyper-
741 visors. This option enables basic hypervisor detection and platform
744 If you say N, all options in this submenu will be skipped and
745 disabled, and Linux guest support won't be built in.
750 bool "Enable paravirtualization code"
752 This changes the kernel so it can modify itself when it is run
753 under a hypervisor, potentially improving performance significantly
754 over full virtualization. However, when run without a hypervisor
755 the kernel is theoretically slower and slightly larger.
760 config PARAVIRT_DEBUG
761 bool "paravirt-ops debugging"
762 depends on PARAVIRT && DEBUG_KERNEL
764 Enable to debug paravirt_ops internals. Specifically, BUG if
765 a paravirt_op is missing when it is called.
767 config PARAVIRT_SPINLOCKS
768 bool "Paravirtualization layer for spinlocks"
769 depends on PARAVIRT && SMP
771 Paravirtualized spinlocks allow a pvops backend to replace the
772 spinlock implementation with something virtualization-friendly
773 (for example, block the virtual CPU rather than spinning).
775 It has a minimal impact on native kernels and gives a nice performance
776 benefit on paravirtualized KVM / Xen kernels.
778 If you are unsure how to answer this question, answer Y.
780 source "arch/x86/xen/Kconfig"
783 bool "KVM Guest support (including kvmclock)"
785 select PARAVIRT_CLOCK
788 This option enables various optimizations for running under the KVM
789 hypervisor. It includes a paravirtualized clock, so that instead
790 of relying on a PIT (or probably other) emulation by the
791 underlying device model, the host provides the guest with
792 timing infrastructure such as time of day, and system time
795 bool "Support for running PVH guests"
797 This option enables the PVH entry point for guest virtual machines
798 as specified in the x86/HVM direct boot ABI.
801 bool "Enable debug information for KVM Guests in debugfs"
802 depends on KVM_GUEST && DEBUG_FS
804 This option enables collection of various statistics for KVM guest.
805 Statistics are displayed in debugfs filesystem. Enabling this option
806 may incur significant overhead.
808 config PARAVIRT_TIME_ACCOUNTING
809 bool "Paravirtual steal time accounting"
812 Select this option to enable fine granularity task steal time
813 accounting. Time spent executing other tasks in parallel with
814 the current vCPU is discounted from the vCPU power. To account for
815 that, there can be a small performance impact.
817 If in doubt, say N here.
819 config PARAVIRT_CLOCK
822 config JAILHOUSE_GUEST
823 bool "Jailhouse non-root cell support"
824 depends on X86_64 && PCI
827 This option allows to run Linux as guest in a Jailhouse non-root
828 cell. You can leave this option disabled if you only want to start
829 Jailhouse and run Linux afterwards in the root cell.
831 endif #HYPERVISOR_GUEST
833 source "arch/x86/Kconfig.cpu"
837 prompt "HPET Timer Support" if X86_32
839 Use the IA-PC HPET (High Precision Event Timer) to manage
840 time in preference to the PIT and RTC, if a HPET is
842 HPET is the next generation timer replacing legacy 8254s.
843 The HPET provides a stable time base on SMP
844 systems, unlike the TSC, but it is more expensive to access,
845 as it is off-chip. The interface used is documented
846 in the HPET spec, revision 1.
848 You can safely choose Y here. However, HPET will only be
849 activated if the platform and the BIOS support this feature.
850 Otherwise the 8254 will be used for timing services.
852 Choose N to continue using the legacy 8254 timer.
854 config HPET_EMULATE_RTC
856 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
859 def_bool y if X86_INTEL_MID
860 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
862 depends on X86_INTEL_MID && SFI
864 APB timer is the replacement for 8254, HPET on X86 MID platforms.
865 The APBT provides a stable time base on SMP
866 systems, unlike the TSC, but it is more expensive to access,
867 as it is off-chip. APB timers are always running regardless of CPU
868 C states, they are used as per CPU clockevent device when possible.
870 # Mark as expert because too many people got it wrong.
871 # The code disables itself when not needed.
874 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
875 bool "Enable DMI scanning" if EXPERT
877 Enabled scanning of DMI to identify machine quirks. Say Y
878 here unless you have verified that your setup is not
879 affected by entries in the DMI blacklist. Required by PNP
883 bool "Old AMD GART IOMMU support"
886 depends on X86_64 && PCI && AMD_NB
888 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
889 GART based hardware IOMMUs.
891 The GART supports full DMA access for devices with 32-bit access
892 limitations, on systems with more than 3 GB. This is usually needed
893 for USB, sound, many IDE/SATA chipsets and some other devices.
895 Newer systems typically have a modern AMD IOMMU, supported via
896 the CONFIG_AMD_IOMMU=y config option.
898 In normal configurations this driver is only active when needed:
899 there's more than 3 GB of memory and the system contains a
900 32-bit limited device.
905 bool "IBM Calgary IOMMU support"
908 depends on X86_64 && PCI
910 Support for hardware IOMMUs in IBM's xSeries x366 and x460
911 systems. Needed to run systems with more than 3GB of memory
912 properly with 32-bit PCI devices that do not support DAC
913 (Double Address Cycle). Calgary also supports bus level
914 isolation, where all DMAs pass through the IOMMU. This
915 prevents them from going anywhere except their intended
916 destination. This catches hard-to-find kernel bugs and
917 mis-behaving drivers and devices that do not use the DMA-API
918 properly to set up their DMA buffers. The IOMMU can be
919 turned off at boot time with the iommu=off parameter.
920 Normally the kernel will make the right choice by itself.
923 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
925 prompt "Should Calgary be enabled by default?"
926 depends on CALGARY_IOMMU
928 Should Calgary be enabled by default? if you choose 'y', Calgary
929 will be used (if it exists). If you choose 'n', Calgary will not be
930 used even if it exists. If you choose 'n' and would like to use
931 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
935 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
936 depends on X86_64 && SMP && DEBUG_KERNEL
937 select CPUMASK_OFFSTACK
939 Enable maximum number of CPUS and NUMA Nodes for this architecture.
943 # The maximum number of CPUs supported:
945 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
946 # and which can be configured interactively in the
947 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
949 # The ranges are different on 32-bit and 64-bit kernels, depending on
950 # hardware capabilities and scalability features of the kernel.
952 # ( If MAXSMP is enabled we just use the highest possible value and disable
953 # interactive configuration. )
956 config NR_CPUS_RANGE_BEGIN
958 default NR_CPUS_RANGE_END if MAXSMP
962 config NR_CPUS_RANGE_END
965 default 64 if SMP && X86_BIGSMP
966 default 8 if SMP && !X86_BIGSMP
969 config NR_CPUS_RANGE_END
972 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
973 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
976 config NR_CPUS_DEFAULT
979 default 32 if X86_BIGSMP
983 config NR_CPUS_DEFAULT
986 default 8192 if MAXSMP
991 int "Maximum number of CPUs" if SMP && !MAXSMP
992 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
993 default NR_CPUS_DEFAULT
995 This allows you to specify the maximum number of CPUs which this
996 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
997 supported value is 8192, otherwise the maximum value is 512. The
998 minimum value which makes sense is 2.
1000 This is purely to save memory: each supported CPU adds about 8KB
1001 to the kernel image.
1008 prompt "Multi-core scheduler support"
1011 Multi-core scheduler support improves the CPU scheduler's decision
1012 making when dealing with multi-core CPU chips at a cost of slightly
1013 increased overhead in some places. If unsure say N here.
1015 config SCHED_MC_PRIO
1016 bool "CPU core priorities scheduler support"
1017 depends on SCHED_MC && CPU_SUP_INTEL
1018 select X86_INTEL_PSTATE
1022 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1023 core ordering determined at manufacturing time, which allows
1024 certain cores to reach higher turbo frequencies (when running
1025 single threaded workloads) than others.
1027 Enabling this kernel feature teaches the scheduler about
1028 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1029 scheduler's CPU selection logic accordingly, so that higher
1030 overall system performance can be achieved.
1032 This feature will have no effect on CPUs without this feature.
1034 If unsure say Y here.
1038 depends on !SMP && X86_LOCAL_APIC
1041 bool "Local APIC support on uniprocessors" if !PCI_MSI
1043 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1045 A local APIC (Advanced Programmable Interrupt Controller) is an
1046 integrated interrupt controller in the CPU. If you have a single-CPU
1047 system which has a processor with a local APIC, you can say Y here to
1048 enable and use it. If you say Y here even though your machine doesn't
1049 have a local APIC, then the kernel will still run with no slowdown at
1050 all. The local APIC supports CPU-generated self-interrupts (timer,
1051 performance counters), and the NMI watchdog which detects hard
1054 config X86_UP_IOAPIC
1055 bool "IO-APIC support on uniprocessors"
1056 depends on X86_UP_APIC
1058 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1059 SMP-capable replacement for PC-style interrupt controllers. Most
1060 SMP systems and many recent uniprocessor systems have one.
1062 If you have a single-CPU system with an IO-APIC, you can say Y here
1063 to use it. If you say Y here even though your machine doesn't have
1064 an IO-APIC, then the kernel will still run with no slowdown at all.
1066 config X86_LOCAL_APIC
1068 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1069 select IRQ_DOMAIN_HIERARCHY
1070 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1074 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1076 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1077 bool "Reroute for broken boot IRQs"
1078 depends on X86_IO_APIC
1080 This option enables a workaround that fixes a source of
1081 spurious interrupts. This is recommended when threaded
1082 interrupt handling is used on systems where the generation of
1083 superfluous "boot interrupts" cannot be disabled.
1085 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1086 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1087 kernel does during interrupt handling). On chipsets where this
1088 boot IRQ generation cannot be disabled, this workaround keeps
1089 the original IRQ line masked so that only the equivalent "boot
1090 IRQ" is delivered to the CPUs. The workaround also tells the
1091 kernel to set up the IRQ handler on the boot IRQ line. In this
1092 way only one interrupt is delivered to the kernel. Otherwise
1093 the spurious second interrupt may cause the kernel to bring
1094 down (vital) interrupt lines.
1096 Only affects "broken" chipsets. Interrupt sharing may be
1097 increased on these systems.
1100 bool "Machine Check / overheating reporting"
1101 select GENERIC_ALLOCATOR
1104 Machine Check support allows the processor to notify the
1105 kernel if it detects a problem (e.g. overheating, data corruption).
1106 The action the kernel takes depends on the severity of the problem,
1107 ranging from warning messages to halting the machine.
1109 config X86_MCELOG_LEGACY
1110 bool "Support for deprecated /dev/mcelog character device"
1113 Enable support for /dev/mcelog which is needed by the old mcelog
1114 userspace logging daemon. Consider switching to the new generation
1117 config X86_MCE_INTEL
1119 prompt "Intel MCE features"
1120 depends on X86_MCE && X86_LOCAL_APIC
1122 Additional support for intel specific MCE features such as
1123 the thermal monitor.
1127 prompt "AMD MCE features"
1128 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1130 Additional support for AMD specific MCE features such as
1131 the DRAM Error Threshold.
1133 config X86_ANCIENT_MCE
1134 bool "Support for old Pentium 5 / WinChip machine checks"
1135 depends on X86_32 && X86_MCE
1137 Include support for machine check handling on old Pentium 5 or WinChip
1138 systems. These typically need to be enabled explicitly on the command
1141 config X86_MCE_THRESHOLD
1142 depends on X86_MCE_AMD || X86_MCE_INTEL
1145 config X86_MCE_INJECT
1146 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1147 tristate "Machine check injector support"
1149 Provide support for injecting machine checks for testing purposes.
1150 If you don't know what a machine check is and you don't do kernel
1151 QA it is safe to say n.
1153 config X86_THERMAL_VECTOR
1155 depends on X86_MCE_INTEL
1157 source "arch/x86/events/Kconfig"
1159 config X86_LEGACY_VM86
1160 bool "Legacy VM86 support"
1163 This option allows user programs to put the CPU into V8086
1164 mode, which is an 80286-era approximation of 16-bit real mode.
1166 Some very old versions of X and/or vbetool require this option
1167 for user mode setting. Similarly, DOSEMU will use it if
1168 available to accelerate real mode DOS programs. However, any
1169 recent version of DOSEMU, X, or vbetool should be fully
1170 functional even without kernel VM86 support, as they will all
1171 fall back to software emulation. Nevertheless, if you are using
1172 a 16-bit DOS program where 16-bit performance matters, vm86
1173 mode might be faster than emulation and you might want to
1176 Note that any app that works on a 64-bit kernel is unlikely to
1177 need this option, as 64-bit kernels don't, and can't, support
1178 V8086 mode. This option is also unrelated to 16-bit protected
1179 mode and is not needed to run most 16-bit programs under Wine.
1181 Enabling this option increases the complexity of the kernel
1182 and slows down exception handling a tiny bit.
1184 If unsure, say N here.
1188 default X86_LEGACY_VM86
1191 bool "Enable support for 16-bit segments" if EXPERT
1193 depends on MODIFY_LDT_SYSCALL
1195 This option is required by programs like Wine to run 16-bit
1196 protected mode legacy code on x86 processors. Disabling
1197 this option saves about 300 bytes on i386, or around 6K text
1198 plus 16K runtime memory on x86-64,
1202 depends on X86_16BIT && X86_32
1206 depends on X86_16BIT && X86_64
1208 config X86_VSYSCALL_EMULATION
1209 bool "Enable vsyscall emulation" if EXPERT
1213 This enables emulation of the legacy vsyscall page. Disabling
1214 it is roughly equivalent to booting with vsyscall=none, except
1215 that it will also disable the helpful warning if a program
1216 tries to use a vsyscall. With this option set to N, offending
1217 programs will just segfault, citing addresses of the form
1220 This option is required by many programs built before 2013, and
1221 care should be used even with newer programs if set to N.
1223 Disabling this option saves about 7K of kernel size and
1224 possibly 4K of additional runtime pagetable memory.
1227 tristate "Toshiba Laptop support"
1230 This adds a driver to safely access the System Management Mode of
1231 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1232 not work on models with a Phoenix BIOS. The System Management Mode
1233 is used to set the BIOS and power saving options on Toshiba portables.
1235 For information on utilities to make use of this driver see the
1236 Toshiba Linux utilities web site at:
1237 <http://www.buzzard.org.uk/toshiba/>.
1239 Say Y if you intend to run this kernel on a Toshiba portable.
1243 tristate "Dell i8k legacy laptop support"
1245 select SENSORS_DELL_SMM
1247 This option enables legacy /proc/i8k userspace interface in hwmon
1248 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1249 temperature and allows controlling fan speeds of Dell laptops via
1250 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1251 it reports also power and hotkey status. For fan speed control is
1252 needed userspace package i8kutils.
1254 Say Y if you intend to run this kernel on old Dell laptops or want to
1255 use userspace package i8kutils.
1258 config X86_REBOOTFIXUPS
1259 bool "Enable X86 board specific fixups for reboot"
1262 This enables chipset and/or board specific fixups to be done
1263 in order to get reboot to work correctly. This is only needed on
1264 some combinations of hardware and BIOS. The symptom, for which
1265 this config is intended, is when reboot ends with a stalled/hung
1268 Currently, the only fixup is for the Geode machines using
1269 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1271 Say Y if you want to enable the fixup. Currently, it's safe to
1272 enable this option even if you don't need it.
1276 bool "CPU microcode loading support"
1278 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1281 If you say Y here, you will be able to update the microcode on
1282 Intel and AMD processors. The Intel support is for the IA32 family,
1283 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1284 AMD support is for families 0x10 and later. You will obviously need
1285 the actual microcode binary data itself which is not shipped with
1288 The preferred method to load microcode from a detached initrd is described
1289 in Documentation/x86/microcode.txt. For that you need to enable
1290 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1291 initrd for microcode blobs.
1293 In addition, you can build the microcode into the kernel. For that you
1294 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1297 config MICROCODE_INTEL
1298 bool "Intel microcode loading support"
1299 depends on MICROCODE
1303 This options enables microcode patch loading support for Intel
1306 For the current Intel microcode data package go to
1307 <https://downloadcenter.intel.com> and search for
1308 'Linux Processor Microcode Data File'.
1310 config MICROCODE_AMD
1311 bool "AMD microcode loading support"
1312 depends on MICROCODE
1315 If you select this option, microcode patch loading support for AMD
1316 processors will be enabled.
1318 config MICROCODE_OLD_INTERFACE
1319 bool "Ancient loading interface (DEPRECATED)"
1321 depends on MICROCODE
1323 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1324 which was used by userspace tools like iucode_tool and microcode.ctl.
1325 It is inadequate because it runs too late to be able to properly
1326 load microcode on a machine and it needs special tools. Instead, you
1327 should've switched to the early loading method with the initrd or
1328 builtin microcode by now: Documentation/x86/microcode.txt
1331 tristate "/dev/cpu/*/msr - Model-specific register support"
1333 This device gives privileged processes access to the x86
1334 Model-Specific Registers (MSRs). It is a character device with
1335 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1336 MSR accesses are directed to a specific CPU on multi-processor
1340 tristate "/dev/cpu/*/cpuid - CPU information support"
1342 This device gives processes access to the x86 CPUID instruction to
1343 be executed on a specific processor. It is a character device
1344 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1348 prompt "High Memory Support"
1355 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1356 However, the address space of 32-bit x86 processors is only 4
1357 Gigabytes large. That means that, if you have a large amount of
1358 physical memory, not all of it can be "permanently mapped" by the
1359 kernel. The physical memory that's not permanently mapped is called
1362 If you are compiling a kernel which will never run on a machine with
1363 more than 1 Gigabyte total physical RAM, answer "off" here (default
1364 choice and suitable for most users). This will result in a "3GB/1GB"
1365 split: 3GB are mapped so that each process sees a 3GB virtual memory
1366 space and the remaining part of the 4GB virtual memory space is used
1367 by the kernel to permanently map as much physical memory as
1370 If the machine has between 1 and 4 Gigabytes physical RAM, then
1373 If more than 4 Gigabytes is used then answer "64GB" here. This
1374 selection turns Intel PAE (Physical Address Extension) mode on.
1375 PAE implements 3-level paging on IA32 processors. PAE is fully
1376 supported by Linux, PAE mode is implemented on all recent Intel
1377 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1378 then the kernel will not boot on CPUs that don't support PAE!
1380 The actual amount of total physical memory will either be
1381 auto detected or can be forced by using a kernel command line option
1382 such as "mem=256M". (Try "man bootparam" or see the documentation of
1383 your boot loader (lilo or loadlin) about how to pass options to the
1384 kernel at boot time.)
1386 If unsure, say "off".
1391 Select this if you have a 32-bit processor and between 1 and 4
1392 gigabytes of physical RAM.
1396 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1399 Select this if you have a 32-bit processor and more than 4
1400 gigabytes of physical RAM.
1405 prompt "Memory split" if EXPERT
1409 Select the desired split between kernel and user memory.
1411 If the address range available to the kernel is less than the
1412 physical memory installed, the remaining memory will be available
1413 as "high memory". Accessing high memory is a little more costly
1414 than low memory, as it needs to be mapped into the kernel first.
1415 Note that increasing the kernel address space limits the range
1416 available to user programs, making the address space there
1417 tighter. Selecting anything other than the default 3G/1G split
1418 will also likely make your kernel incompatible with binary-only
1421 If you are not absolutely sure what you are doing, leave this
1425 bool "3G/1G user/kernel split"
1426 config VMSPLIT_3G_OPT
1428 bool "3G/1G user/kernel split (for full 1G low memory)"
1430 bool "2G/2G user/kernel split"
1431 config VMSPLIT_2G_OPT
1433 bool "2G/2G user/kernel split (for full 2G low memory)"
1435 bool "1G/3G user/kernel split"
1440 default 0xB0000000 if VMSPLIT_3G_OPT
1441 default 0x80000000 if VMSPLIT_2G
1442 default 0x78000000 if VMSPLIT_2G_OPT
1443 default 0x40000000 if VMSPLIT_1G
1449 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1452 bool "PAE (Physical Address Extension) Support"
1453 depends on X86_32 && !HIGHMEM4G
1454 select PHYS_ADDR_T_64BIT
1457 PAE is required for NX support, and furthermore enables
1458 larger swapspace support for non-overcommit purposes. It
1459 has the cost of more pagetable lookup overhead, and also
1460 consumes more pagetable space per process.
1463 bool "Enable 5-level page tables support"
1464 select DYNAMIC_MEMORY_LAYOUT
1465 select SPARSEMEM_VMEMMAP
1468 5-level paging enables access to larger address space:
1469 upto 128 PiB of virtual address space and 4 PiB of
1470 physical address space.
1472 It will be supported by future Intel CPUs.
1474 A kernel with the option enabled can be booted on machines that
1475 support 4- or 5-level paging.
1477 See Documentation/x86/x86_64/5level-paging.txt for more
1482 config X86_DIRECT_GBPAGES
1484 depends on X86_64 && !DEBUG_PAGEALLOC
1486 Certain kernel features effectively disable kernel
1487 linear 1 GB mappings (even if the CPU otherwise
1488 supports them), so don't confuse the user by printing
1489 that we have them enabled.
1491 config X86_CPA_STATISTICS
1492 bool "Enable statistic for Change Page Attribute"
1495 Expose statistics about the Change Page Attribute mechanims, which
1496 helps to determine the effectiveness of preserving large and huge
1497 page mappings when mapping protections are changed.
1499 config ARCH_HAS_MEM_ENCRYPT
1502 config AMD_MEM_ENCRYPT
1503 bool "AMD Secure Memory Encryption (SME) support"
1504 depends on X86_64 && CPU_SUP_AMD
1505 select DYNAMIC_PHYSICAL_MASK
1506 select ARCH_USE_MEMREMAP_PROT
1508 Say yes to enable support for the encryption of system memory.
1509 This requires an AMD processor that supports Secure Memory
1512 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1513 bool "Activate AMD Secure Memory Encryption (SME) by default"
1515 depends on AMD_MEM_ENCRYPT
1517 Say yes to have system memory encrypted by default if running on
1518 an AMD processor that supports Secure Memory Encryption (SME).
1520 If set to Y, then the encryption of system memory can be
1521 deactivated with the mem_encrypt=off command line option.
1523 If set to N, then the encryption of system memory can be
1524 activated with the mem_encrypt=on command line option.
1526 # Common NUMA Features
1528 bool "Numa Memory Allocation and Scheduler Support"
1530 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1531 default y if X86_BIGSMP
1533 Enable NUMA (Non Uniform Memory Access) support.
1535 The kernel will try to allocate memory used by a CPU on the
1536 local memory controller of the CPU and add some more
1537 NUMA awareness to the kernel.
1539 For 64-bit this is recommended if the system is Intel Core i7
1540 (or later), AMD Opteron, or EM64T NUMA.
1542 For 32-bit this is only needed if you boot a 32-bit
1543 kernel on a 64-bit NUMA platform.
1545 Otherwise, you should say N.
1549 prompt "Old style AMD Opteron NUMA detection"
1550 depends on X86_64 && NUMA && PCI
1552 Enable AMD NUMA node topology detection. You should say Y here if
1553 you have a multi processor AMD system. This uses an old method to
1554 read the NUMA configuration directly from the builtin Northbridge
1555 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1556 which also takes priority if both are compiled in.
1558 config X86_64_ACPI_NUMA
1560 prompt "ACPI NUMA detection"
1561 depends on X86_64 && NUMA && ACPI && PCI
1564 Enable ACPI SRAT based node topology detection.
1566 # Some NUMA nodes have memory ranges that span
1567 # other nodes. Even though a pfn is valid and
1568 # between a node's start and end pfns, it may not
1569 # reside on that node. See memmap_init_zone()
1571 config NODES_SPAN_OTHER_NODES
1573 depends on X86_64_ACPI_NUMA
1576 bool "NUMA emulation"
1579 Enable NUMA emulation. A flat machine will be split
1580 into virtual nodes when booted with "numa=fake=N", where N is the
1581 number of nodes. This is only useful for debugging.
1584 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1586 default "10" if MAXSMP
1587 default "6" if X86_64
1589 depends on NEED_MULTIPLE_NODES
1591 Specify the maximum number of NUMA Nodes available on the target
1592 system. Increases memory reserved to accommodate various tables.
1594 config ARCH_HAVE_MEMORY_PRESENT
1596 depends on X86_32 && DISCONTIGMEM
1598 config ARCH_FLATMEM_ENABLE
1600 depends on X86_32 && !NUMA
1602 config ARCH_DISCONTIGMEM_ENABLE
1604 depends on NUMA && X86_32
1607 config ARCH_SPARSEMEM_ENABLE
1609 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1610 select SPARSEMEM_STATIC if X86_32
1611 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1613 config ARCH_SPARSEMEM_DEFAULT
1614 def_bool X86_64 || (NUMA && X86_32)
1616 config ARCH_SELECT_MEMORY_MODEL
1618 depends on ARCH_SPARSEMEM_ENABLE
1620 config ARCH_MEMORY_PROBE
1621 bool "Enable sysfs memory/probe interface"
1622 depends on X86_64 && MEMORY_HOTPLUG
1624 This option enables a sysfs memory/probe interface for testing.
1625 See Documentation/memory-hotplug.txt for more information.
1626 If you are unsure how to answer this question, answer N.
1628 config ARCH_PROC_KCORE_TEXT
1630 depends on X86_64 && PROC_KCORE
1632 config ILLEGAL_POINTER_VALUE
1635 default 0xdead000000000000 if X86_64
1637 config X86_PMEM_LEGACY_DEVICE
1640 config X86_PMEM_LEGACY
1641 tristate "Support non-standard NVDIMMs and ADR protected memory"
1642 depends on PHYS_ADDR_T_64BIT
1644 select X86_PMEM_LEGACY_DEVICE
1647 Treat memory marked using the non-standard e820 type of 12 as used
1648 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1649 The kernel will offer these regions to the 'pmem' driver so
1650 they can be used for persistent storage.
1655 bool "Allocate 3rd-level pagetables from highmem"
1658 The VM uses one page table entry for each page of physical memory.
1659 For systems with a lot of RAM, this can be wasteful of precious
1660 low memory. Setting this option will put user-space page table
1661 entries in high memory.
1663 config X86_CHECK_BIOS_CORRUPTION
1664 bool "Check for low memory corruption"
1666 Periodically check for memory corruption in low memory, which
1667 is suspected to be caused by BIOS. Even when enabled in the
1668 configuration, it is disabled at runtime. Enable it by
1669 setting "memory_corruption_check=1" on the kernel command
1670 line. By default it scans the low 64k of memory every 60
1671 seconds; see the memory_corruption_check_size and
1672 memory_corruption_check_period parameters in
1673 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1675 When enabled with the default parameters, this option has
1676 almost no overhead, as it reserves a relatively small amount
1677 of memory and scans it infrequently. It both detects corruption
1678 and prevents it from affecting the running system.
1680 It is, however, intended as a diagnostic tool; if repeatable
1681 BIOS-originated corruption always affects the same memory,
1682 you can use memmap= to prevent the kernel from using that
1685 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1686 bool "Set the default setting of memory_corruption_check"
1687 depends on X86_CHECK_BIOS_CORRUPTION
1690 Set whether the default state of memory_corruption_check is
1693 config X86_RESERVE_LOW
1694 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1698 Specify the amount of low memory to reserve for the BIOS.
1700 The first page contains BIOS data structures that the kernel
1701 must not use, so that page must always be reserved.
1703 By default we reserve the first 64K of physical RAM, as a
1704 number of BIOSes are known to corrupt that memory range
1705 during events such as suspend/resume or monitor cable
1706 insertion, so it must not be used by the kernel.
1708 You can set this to 4 if you are absolutely sure that you
1709 trust the BIOS to get all its memory reservations and usages
1710 right. If you know your BIOS have problems beyond the
1711 default 64K area, you can set this to 640 to avoid using the
1712 entire low memory range.
1714 If you have doubts about the BIOS (e.g. suspend/resume does
1715 not work or there's kernel crashes after certain hardware
1716 hotplug events) then you might want to enable
1717 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1718 typical corruption patterns.
1720 Leave this to the default value of 64 if you are unsure.
1722 config MATH_EMULATION
1724 depends on MODIFY_LDT_SYSCALL
1725 prompt "Math emulation" if X86_32
1727 Linux can emulate a math coprocessor (used for floating point
1728 operations) if you don't have one. 486DX and Pentium processors have
1729 a math coprocessor built in, 486SX and 386 do not, unless you added
1730 a 487DX or 387, respectively. (The messages during boot time can
1731 give you some hints here ["man dmesg"].) Everyone needs either a
1732 coprocessor or this emulation.
1734 If you don't have a math coprocessor, you need to say Y here; if you
1735 say Y here even though you have a coprocessor, the coprocessor will
1736 be used nevertheless. (This behavior can be changed with the kernel
1737 command line option "no387", which comes handy if your coprocessor
1738 is broken. Try "man bootparam" or see the documentation of your boot
1739 loader (lilo or loadlin) about how to pass options to the kernel at
1740 boot time.) This means that it is a good idea to say Y here if you
1741 intend to use this kernel on different machines.
1743 More information about the internals of the Linux math coprocessor
1744 emulation can be found in <file:arch/x86/math-emu/README>.
1746 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1747 kernel, it won't hurt.
1751 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1753 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1754 the Memory Type Range Registers (MTRRs) may be used to control
1755 processor access to memory ranges. This is most useful if you have
1756 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1757 allows bus write transfers to be combined into a larger transfer
1758 before bursting over the PCI/AGP bus. This can increase performance
1759 of image write operations 2.5 times or more. Saying Y here creates a
1760 /proc/mtrr file which may be used to manipulate your processor's
1761 MTRRs. Typically the X server should use this.
1763 This code has a reasonably generic interface so that similar
1764 control registers on other processors can be easily supported
1767 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1768 Registers (ARRs) which provide a similar functionality to MTRRs. For
1769 these, the ARRs are used to emulate the MTRRs.
1770 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1771 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1772 write-combining. All of these processors are supported by this code
1773 and it makes sense to say Y here if you have one of them.
1775 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1776 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1777 can lead to all sorts of problems, so it's good to say Y here.
1779 You can safely say Y even if your machine doesn't have MTRRs, you'll
1780 just add about 9 KB to your kernel.
1782 See <file:Documentation/x86/mtrr.txt> for more information.
1784 config MTRR_SANITIZER
1786 prompt "MTRR cleanup support"
1789 Convert MTRR layout from continuous to discrete, so X drivers can
1790 add writeback entries.
1792 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1793 The largest mtrr entry size for a continuous block can be set with
1798 config MTRR_SANITIZER_ENABLE_DEFAULT
1799 int "MTRR cleanup enable value (0-1)"
1802 depends on MTRR_SANITIZER
1804 Enable mtrr cleanup default value
1806 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1807 int "MTRR cleanup spare reg num (0-7)"
1810 depends on MTRR_SANITIZER
1812 mtrr cleanup spare entries default, it can be changed via
1813 mtrr_spare_reg_nr=N on the kernel command line.
1817 prompt "x86 PAT support" if EXPERT
1820 Use PAT attributes to setup page level cache control.
1822 PATs are the modern equivalents of MTRRs and are much more
1823 flexible than MTRRs.
1825 Say N here if you see bootup problems (boot crash, boot hang,
1826 spontaneous reboots) or a non-working video driver.
1830 config ARCH_USES_PG_UNCACHED
1836 prompt "x86 architectural random number generator" if EXPERT
1838 Enable the x86 architectural RDRAND instruction
1839 (Intel Bull Mountain technology) to generate random numbers.
1840 If supported, this is a high bandwidth, cryptographically
1841 secure hardware random number generator.
1845 prompt "Supervisor Mode Access Prevention" if EXPERT
1847 Supervisor Mode Access Prevention (SMAP) is a security
1848 feature in newer Intel processors. There is a small
1849 performance cost if this enabled and turned on; there is
1850 also a small increase in the kernel size if this is enabled.
1854 config X86_INTEL_UMIP
1856 depends on CPU_SUP_INTEL
1857 prompt "Intel User Mode Instruction Prevention" if EXPERT
1859 The User Mode Instruction Prevention (UMIP) is a security
1860 feature in newer Intel processors. If enabled, a general
1861 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1862 or STR instructions are executed in user mode. These instructions
1863 unnecessarily expose information about the hardware state.
1865 The vast majority of applications do not use these instructions.
1866 For the very few that do, software emulation is provided in
1867 specific cases in protected and virtual-8086 modes. Emulated
1870 config X86_INTEL_MPX
1871 prompt "Intel MPX (Memory Protection Extensions)"
1873 # Note: only available in 64-bit mode due to VMA flags shortage
1874 depends on CPU_SUP_INTEL && X86_64
1875 select ARCH_USES_HIGH_VMA_FLAGS
1877 MPX provides hardware features that can be used in
1878 conjunction with compiler-instrumented code to check
1879 memory references. It is designed to detect buffer
1880 overflow or underflow bugs.
1882 This option enables running applications which are
1883 instrumented or otherwise use MPX. It does not use MPX
1884 itself inside the kernel or to protect the kernel
1885 against bad memory references.
1887 Enabling this option will make the kernel larger:
1888 ~8k of kernel text and 36 bytes of data on a 64-bit
1889 defconfig. It adds a long to the 'mm_struct' which
1890 will increase the kernel memory overhead of each
1891 process and adds some branches to paths used during
1892 exec() and munmap().
1894 For details, see Documentation/x86/intel_mpx.txt
1898 config X86_INTEL_MEMORY_PROTECTION_KEYS
1899 prompt "Intel Memory Protection Keys"
1901 # Note: only available in 64-bit mode
1902 depends on CPU_SUP_INTEL && X86_64
1903 select ARCH_USES_HIGH_VMA_FLAGS
1904 select ARCH_HAS_PKEYS
1906 Memory Protection Keys provides a mechanism for enforcing
1907 page-based protections, but without requiring modification of the
1908 page tables when an application changes protection domains.
1910 For details, see Documentation/x86/protection-keys.txt
1915 bool "EFI runtime service support"
1918 select EFI_RUNTIME_WRAPPERS
1920 This enables the kernel to use EFI runtime services that are
1921 available (such as the EFI variable services).
1923 This option is only useful on systems that have EFI firmware.
1924 In addition, you should use the latest ELILO loader available
1925 at <http://elilo.sourceforge.net> in order to take advantage
1926 of EFI runtime services. However, even with this option, the
1927 resultant kernel should continue to boot on existing non-EFI
1931 bool "EFI stub support"
1932 depends on EFI && !X86_USE_3DNOW
1935 This kernel feature allows a bzImage to be loaded directly
1936 by EFI firmware without the use of a bootloader.
1938 See Documentation/efi-stub.txt for more information.
1941 bool "EFI mixed-mode support"
1942 depends on EFI_STUB && X86_64
1944 Enabling this feature allows a 64-bit kernel to be booted
1945 on a 32-bit firmware, provided that your CPU supports 64-bit
1948 Note that it is not possible to boot a mixed-mode enabled
1949 kernel via the EFI boot stub - a bootloader that supports
1950 the EFI handover protocol must be used.
1956 prompt "Enable seccomp to safely compute untrusted bytecode"
1958 This kernel feature is useful for number crunching applications
1959 that may need to compute untrusted bytecode during their
1960 execution. By using pipes or other transports made available to
1961 the process as file descriptors supporting the read/write
1962 syscalls, it's possible to isolate those applications in
1963 their own address space using seccomp. Once seccomp is
1964 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1965 and the task is only allowed to execute a few safe syscalls
1966 defined by each seccomp mode.
1968 If unsure, say Y. Only embedded should say N here.
1970 source "kernel/Kconfig.hz"
1973 bool "kexec system call"
1976 kexec is a system call that implements the ability to shutdown your
1977 current kernel, and to start another kernel. It is like a reboot
1978 but it is independent of the system firmware. And like a reboot
1979 you can start any kernel with it, not just Linux.
1981 The name comes from the similarity to the exec system call.
1983 It is an ongoing process to be certain the hardware in a machine
1984 is properly shutdown, so do not be surprised if this code does not
1985 initially work for you. As of this writing the exact hardware
1986 interface is strongly in flux, so no good recommendation can be
1990 bool "kexec file based system call"
1995 depends on CRYPTO_SHA256=y
1997 This is new version of kexec system call. This system call is
1998 file based and takes file descriptors as system call argument
1999 for kernel and initramfs as opposed to list of segments as
2000 accepted by previous system call.
2002 config ARCH_HAS_KEXEC_PURGATORY
2005 config KEXEC_VERIFY_SIG
2006 bool "Verify kernel signature during kexec_file_load() syscall"
2007 depends on KEXEC_FILE
2009 This option makes kernel signature verification mandatory for
2010 the kexec_file_load() syscall.
2012 In addition to that option, you need to enable signature
2013 verification for the corresponding kernel image type being
2014 loaded in order for this to work.
2016 config KEXEC_BZIMAGE_VERIFY_SIG
2017 bool "Enable bzImage signature verification support"
2018 depends on KEXEC_VERIFY_SIG
2019 depends on SIGNED_PE_FILE_VERIFICATION
2020 select SYSTEM_TRUSTED_KEYRING
2022 Enable bzImage signature verification support.
2025 bool "kernel crash dumps"
2026 depends on X86_64 || (X86_32 && HIGHMEM)
2028 Generate crash dump after being started by kexec.
2029 This should be normally only set in special crash dump kernels
2030 which are loaded in the main kernel with kexec-tools into
2031 a specially reserved region and then later executed after
2032 a crash by kdump/kexec. The crash dump kernel must be compiled
2033 to a memory address not used by the main kernel or BIOS using
2034 PHYSICAL_START, or it must be built as a relocatable image
2035 (CONFIG_RELOCATABLE=y).
2036 For more details see Documentation/kdump/kdump.txt
2040 depends on KEXEC && HIBERNATION
2042 Jump between original kernel and kexeced kernel and invoke
2043 code in physical address mode via KEXEC
2045 config PHYSICAL_START
2046 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2049 This gives the physical address where the kernel is loaded.
2051 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2052 bzImage will decompress itself to above physical address and
2053 run from there. Otherwise, bzImage will run from the address where
2054 it has been loaded by the boot loader and will ignore above physical
2057 In normal kdump cases one does not have to set/change this option
2058 as now bzImage can be compiled as a completely relocatable image
2059 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2060 address. This option is mainly useful for the folks who don't want
2061 to use a bzImage for capturing the crash dump and want to use a
2062 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2063 to be specifically compiled to run from a specific memory area
2064 (normally a reserved region) and this option comes handy.
2066 So if you are using bzImage for capturing the crash dump,
2067 leave the value here unchanged to 0x1000000 and set
2068 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2069 for capturing the crash dump change this value to start of
2070 the reserved region. In other words, it can be set based on
2071 the "X" value as specified in the "crashkernel=YM@XM"
2072 command line boot parameter passed to the panic-ed
2073 kernel. Please take a look at Documentation/kdump/kdump.txt
2074 for more details about crash dumps.
2076 Usage of bzImage for capturing the crash dump is recommended as
2077 one does not have to build two kernels. Same kernel can be used
2078 as production kernel and capture kernel. Above option should have
2079 gone away after relocatable bzImage support is introduced. But it
2080 is present because there are users out there who continue to use
2081 vmlinux for dump capture. This option should go away down the
2084 Don't change this unless you know what you are doing.
2087 bool "Build a relocatable kernel"
2090 This builds a kernel image that retains relocation information
2091 so it can be loaded someplace besides the default 1MB.
2092 The relocations tend to make the kernel binary about 10% larger,
2093 but are discarded at runtime.
2095 One use is for the kexec on panic case where the recovery kernel
2096 must live at a different physical address than the primary
2099 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2100 it has been loaded at and the compile time physical address
2101 (CONFIG_PHYSICAL_START) is used as the minimum location.
2103 config RANDOMIZE_BASE
2104 bool "Randomize the address of the kernel image (KASLR)"
2105 depends on RELOCATABLE
2108 In support of Kernel Address Space Layout Randomization (KASLR),
2109 this randomizes the physical address at which the kernel image
2110 is decompressed and the virtual address where the kernel
2111 image is mapped, as a security feature that deters exploit
2112 attempts relying on knowledge of the location of kernel
2115 On 64-bit, the kernel physical and virtual addresses are
2116 randomized separately. The physical address will be anywhere
2117 between 16MB and the top of physical memory (up to 64TB). The
2118 virtual address will be randomized from 16MB up to 1GB (9 bits
2119 of entropy). Note that this also reduces the memory space
2120 available to kernel modules from 1.5GB to 1GB.
2122 On 32-bit, the kernel physical and virtual addresses are
2123 randomized together. They will be randomized from 16MB up to
2124 512MB (8 bits of entropy).
2126 Entropy is generated using the RDRAND instruction if it is
2127 supported. If RDTSC is supported, its value is mixed into
2128 the entropy pool as well. If neither RDRAND nor RDTSC are
2129 supported, then entropy is read from the i8254 timer. The
2130 usable entropy is limited by the kernel being built using
2131 2GB addressing, and that PHYSICAL_ALIGN must be at a
2132 minimum of 2MB. As a result, only 10 bits of entropy are
2133 theoretically possible, but the implementations are further
2134 limited due to memory layouts.
2138 # Relocation on x86 needs some additional build support
2139 config X86_NEED_RELOCS
2141 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2143 config PHYSICAL_ALIGN
2144 hex "Alignment value to which kernel should be aligned"
2146 range 0x2000 0x1000000 if X86_32
2147 range 0x200000 0x1000000 if X86_64
2149 This value puts the alignment restrictions on physical address
2150 where kernel is loaded and run from. Kernel is compiled for an
2151 address which meets above alignment restriction.
2153 If bootloader loads the kernel at a non-aligned address and
2154 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2155 address aligned to above value and run from there.
2157 If bootloader loads the kernel at a non-aligned address and
2158 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2159 load address and decompress itself to the address it has been
2160 compiled for and run from there. The address for which kernel is
2161 compiled already meets above alignment restrictions. Hence the
2162 end result is that kernel runs from a physical address meeting
2163 above alignment restrictions.
2165 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2166 this value must be a multiple of 0x200000.
2168 Don't change this unless you know what you are doing.
2170 config DYNAMIC_MEMORY_LAYOUT
2173 This option makes base addresses of vmalloc and vmemmap as well as
2174 __PAGE_OFFSET movable during boot.
2176 config RANDOMIZE_MEMORY
2177 bool "Randomize the kernel memory sections"
2179 depends on RANDOMIZE_BASE
2180 select DYNAMIC_MEMORY_LAYOUT
2181 default RANDOMIZE_BASE
2183 Randomizes the base virtual address of kernel memory sections
2184 (physical memory mapping, vmalloc & vmemmap). This security feature
2185 makes exploits relying on predictable memory locations less reliable.
2187 The order of allocations remains unchanged. Entropy is generated in
2188 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2189 configuration have in average 30,000 different possible virtual
2190 addresses for each memory section.
2194 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2195 hex "Physical memory mapping padding" if EXPERT
2196 depends on RANDOMIZE_MEMORY
2197 default "0xa" if MEMORY_HOTPLUG
2199 range 0x1 0x40 if MEMORY_HOTPLUG
2202 Define the padding in terabytes added to the existing physical
2203 memory size during kernel memory randomization. It is useful
2204 for memory hotplug support but reduces the entropy available for
2205 address randomization.
2207 If unsure, leave at the default value.
2213 config BOOTPARAM_HOTPLUG_CPU0
2214 bool "Set default setting of cpu0_hotpluggable"
2215 depends on HOTPLUG_CPU
2217 Set whether default state of cpu0_hotpluggable is on or off.
2219 Say Y here to enable CPU0 hotplug by default. If this switch
2220 is turned on, there is no need to give cpu0_hotplug kernel
2221 parameter and the CPU0 hotplug feature is enabled by default.
2223 Please note: there are two known CPU0 dependencies if you want
2224 to enable the CPU0 hotplug feature either by this switch or by
2225 cpu0_hotplug kernel parameter.
2227 First, resume from hibernate or suspend always starts from CPU0.
2228 So hibernate and suspend are prevented if CPU0 is offline.
2230 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2231 offline if any interrupt can not migrate out of CPU0. There may
2232 be other CPU0 dependencies.
2234 Please make sure the dependencies are under your control before
2235 you enable this feature.
2237 Say N if you don't want to enable CPU0 hotplug feature by default.
2238 You still can enable the CPU0 hotplug feature at boot by kernel
2239 parameter cpu0_hotplug.
2241 config DEBUG_HOTPLUG_CPU0
2243 prompt "Debug CPU0 hotplug"
2244 depends on HOTPLUG_CPU
2246 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2247 soon as possible and boots up userspace with CPU0 offlined. User
2248 can online CPU0 back after boot time.
2250 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2251 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2252 compilation or giving cpu0_hotplug kernel parameter at boot.
2258 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2259 depends on COMPAT_32
2261 Certain buggy versions of glibc will crash if they are
2262 presented with a 32-bit vDSO that is not mapped at the address
2263 indicated in its segment table.
2265 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2266 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2267 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2268 the only released version with the bug, but OpenSUSE 9
2269 contains a buggy "glibc 2.3.2".
2271 The symptom of the bug is that everything crashes on startup, saying:
2272 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2274 Saying Y here changes the default value of the vdso32 boot
2275 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2276 This works around the glibc bug but hurts performance.
2278 If unsure, say N: if you are compiling your own kernel, you
2279 are unlikely to be using a buggy version of glibc.
2282 prompt "vsyscall table for legacy applications"
2284 default LEGACY_VSYSCALL_EMULATE
2286 Legacy user code that does not know how to find the vDSO expects
2287 to be able to issue three syscalls by calling fixed addresses in
2288 kernel space. Since this location is not randomized with ASLR,
2289 it can be used to assist security vulnerability exploitation.
2291 This setting can be changed at boot time via the kernel command
2292 line parameter vsyscall=[emulate|none].
2294 On a system with recent enough glibc (2.14 or newer) and no
2295 static binaries, you can say None without a performance penalty
2296 to improve security.
2298 If unsure, select "Emulate".
2300 config LEGACY_VSYSCALL_EMULATE
2303 The kernel traps and emulates calls into the fixed
2304 vsyscall address mapping. This makes the mapping
2305 non-executable, but it still contains known contents,
2306 which could be used in certain rare security vulnerability
2307 exploits. This configuration is recommended when userspace
2308 still uses the vsyscall area.
2310 config LEGACY_VSYSCALL_NONE
2313 There will be no vsyscall mapping at all. This will
2314 eliminate any risk of ASLR bypass due to the vsyscall
2315 fixed address mapping. Attempts to use the vsyscalls
2316 will be reported to dmesg, so that either old or
2317 malicious userspace programs can be identified.
2322 bool "Built-in kernel command line"
2324 Allow for specifying boot arguments to the kernel at
2325 build time. On some systems (e.g. embedded ones), it is
2326 necessary or convenient to provide some or all of the
2327 kernel boot arguments with the kernel itself (that is,
2328 to not rely on the boot loader to provide them.)
2330 To compile command line arguments into the kernel,
2331 set this option to 'Y', then fill in the
2332 boot arguments in CONFIG_CMDLINE.
2334 Systems with fully functional boot loaders (i.e. non-embedded)
2335 should leave this option set to 'N'.
2338 string "Built-in kernel command string"
2339 depends on CMDLINE_BOOL
2342 Enter arguments here that should be compiled into the kernel
2343 image and used at boot time. If the boot loader provides a
2344 command line at boot time, it is appended to this string to
2345 form the full kernel command line, when the system boots.
2347 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2348 change this behavior.
2350 In most cases, the command line (whether built-in or provided
2351 by the boot loader) should specify the device for the root
2354 config CMDLINE_OVERRIDE
2355 bool "Built-in command line overrides boot loader arguments"
2356 depends on CMDLINE_BOOL
2358 Set this option to 'Y' to have the kernel ignore the boot loader
2359 command line, and use ONLY the built-in command line.
2361 This is used to work around broken boot loaders. This should
2362 be set to 'N' under normal conditions.
2364 config MODIFY_LDT_SYSCALL
2365 bool "Enable the LDT (local descriptor table)" if EXPERT
2368 Linux can allow user programs to install a per-process x86
2369 Local Descriptor Table (LDT) using the modify_ldt(2) system
2370 call. This is required to run 16-bit or segmented code such as
2371 DOSEMU or some Wine programs. It is also used by some very old
2372 threading libraries.
2374 Enabling this feature adds a small amount of overhead to
2375 context switches and increases the low-level kernel attack
2376 surface. Disabling it removes the modify_ldt(2) system call.
2378 Saying 'N' here may make sense for embedded or server kernels.
2380 source "kernel/livepatch/Kconfig"
2384 config ARCH_HAS_ADD_PAGES
2386 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2388 config ARCH_ENABLE_MEMORY_HOTPLUG
2390 depends on X86_64 || (X86_32 && HIGHMEM)
2392 config ARCH_ENABLE_MEMORY_HOTREMOVE
2394 depends on MEMORY_HOTPLUG
2396 config USE_PERCPU_NUMA_NODE_ID
2400 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2402 depends on X86_64 || X86_PAE
2404 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2406 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2408 config ARCH_ENABLE_THP_MIGRATION
2410 depends on X86_64 && TRANSPARENT_HUGEPAGE
2412 menu "Power management and ACPI options"
2414 config ARCH_HIBERNATION_HEADER
2416 depends on HIBERNATION
2418 source "kernel/power/Kconfig"
2420 source "drivers/acpi/Kconfig"
2422 source "drivers/sfi/Kconfig"
2429 tristate "APM (Advanced Power Management) BIOS support"
2430 depends on X86_32 && PM_SLEEP
2432 APM is a BIOS specification for saving power using several different
2433 techniques. This is mostly useful for battery powered laptops with
2434 APM compliant BIOSes. If you say Y here, the system time will be
2435 reset after a RESUME operation, the /proc/apm device will provide
2436 battery status information, and user-space programs will receive
2437 notification of APM "events" (e.g. battery status change).
2439 If you select "Y" here, you can disable actual use of the APM
2440 BIOS by passing the "apm=off" option to the kernel at boot time.
2442 Note that the APM support is almost completely disabled for
2443 machines with more than one CPU.
2445 In order to use APM, you will need supporting software. For location
2446 and more information, read <file:Documentation/power/apm-acpi.txt>
2447 and the Battery Powered Linux mini-HOWTO, available from
2448 <http://www.tldp.org/docs.html#howto>.
2450 This driver does not spin down disk drives (see the hdparm(8)
2451 manpage ("man 8 hdparm") for that), and it doesn't turn off
2452 VESA-compliant "green" monitors.
2454 This driver does not support the TI 4000M TravelMate and the ACER
2455 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2456 desktop machines also don't have compliant BIOSes, and this driver
2457 may cause those machines to panic during the boot phase.
2459 Generally, if you don't have a battery in your machine, there isn't
2460 much point in using this driver and you should say N. If you get
2461 random kernel OOPSes or reboots that don't seem to be related to
2462 anything, try disabling/enabling this option (or disabling/enabling
2465 Some other things you should try when experiencing seemingly random,
2468 1) make sure that you have enough swap space and that it is
2470 2) pass the "no-hlt" option to the kernel
2471 3) switch on floating point emulation in the kernel and pass
2472 the "no387" option to the kernel
2473 4) pass the "floppy=nodma" option to the kernel
2474 5) pass the "mem=4M" option to the kernel (thereby disabling
2475 all but the first 4 MB of RAM)
2476 6) make sure that the CPU is not over clocked.
2477 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2478 8) disable the cache from your BIOS settings
2479 9) install a fan for the video card or exchange video RAM
2480 10) install a better fan for the CPU
2481 11) exchange RAM chips
2482 12) exchange the motherboard.
2484 To compile this driver as a module, choose M here: the
2485 module will be called apm.
2489 config APM_IGNORE_USER_SUSPEND
2490 bool "Ignore USER SUSPEND"
2492 This option will ignore USER SUSPEND requests. On machines with a
2493 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2494 series notebooks, it is necessary to say Y because of a BIOS bug.
2496 config APM_DO_ENABLE
2497 bool "Enable PM at boot time"
2499 Enable APM features at boot time. From page 36 of the APM BIOS
2500 specification: "When disabled, the APM BIOS does not automatically
2501 power manage devices, enter the Standby State, enter the Suspend
2502 State, or take power saving steps in response to CPU Idle calls."
2503 This driver will make CPU Idle calls when Linux is idle (unless this
2504 feature is turned off -- see "Do CPU IDLE calls", below). This
2505 should always save battery power, but more complicated APM features
2506 will be dependent on your BIOS implementation. You may need to turn
2507 this option off if your computer hangs at boot time when using APM
2508 support, or if it beeps continuously instead of suspending. Turn
2509 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2510 T400CDT. This is off by default since most machines do fine without
2515 bool "Make CPU Idle calls when idle"
2517 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2518 On some machines, this can activate improved power savings, such as
2519 a slowed CPU clock rate, when the machine is idle. These idle calls
2520 are made after the idle loop has run for some length of time (e.g.,
2521 333 mS). On some machines, this will cause a hang at boot time or
2522 whenever the CPU becomes idle. (On machines with more than one CPU,
2523 this option does nothing.)
2525 config APM_DISPLAY_BLANK
2526 bool "Enable console blanking using APM"
2528 Enable console blanking using the APM. Some laptops can use this to
2529 turn off the LCD backlight when the screen blanker of the Linux
2530 virtual console blanks the screen. Note that this is only used by
2531 the virtual console screen blanker, and won't turn off the backlight
2532 when using the X Window system. This also doesn't have anything to
2533 do with your VESA-compliant power-saving monitor. Further, this
2534 option doesn't work for all laptops -- it might not turn off your
2535 backlight at all, or it might print a lot of errors to the console,
2536 especially if you are using gpm.
2538 config APM_ALLOW_INTS
2539 bool "Allow interrupts during APM BIOS calls"
2541 Normally we disable external interrupts while we are making calls to
2542 the APM BIOS as a measure to lessen the effects of a badly behaving
2543 BIOS implementation. The BIOS should reenable interrupts if it
2544 needs to. Unfortunately, some BIOSes do not -- especially those in
2545 many of the newer IBM Thinkpads. If you experience hangs when you
2546 suspend, try setting this to Y. Otherwise, say N.
2550 source "drivers/cpufreq/Kconfig"
2552 source "drivers/cpuidle/Kconfig"
2554 source "drivers/idle/Kconfig"
2559 menu "Bus options (PCI etc.)"
2562 prompt "PCI access mode"
2563 depends on X86_32 && PCI
2566 On PCI systems, the BIOS can be used to detect the PCI devices and
2567 determine their configuration. However, some old PCI motherboards
2568 have BIOS bugs and may crash if this is done. Also, some embedded
2569 PCI-based systems don't have any BIOS at all. Linux can also try to
2570 detect the PCI hardware directly without using the BIOS.
2572 With this option, you can specify how Linux should detect the
2573 PCI devices. If you choose "BIOS", the BIOS will be used,
2574 if you choose "Direct", the BIOS won't be used, and if you
2575 choose "MMConfig", then PCI Express MMCONFIG will be used.
2576 If you choose "Any", the kernel will try MMCONFIG, then the
2577 direct access method and falls back to the BIOS if that doesn't
2578 work. If unsure, go with the default, which is "Any".
2583 config PCI_GOMMCONFIG
2600 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2602 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2605 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2608 bool "Support mmconfig PCI config space access" if X86_64
2610 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2611 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2615 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2619 depends on PCI && XEN
2622 config MMCONF_FAM10H
2624 depends on X86_64 && PCI_MMCONFIG && ACPI
2626 config PCI_CNB20LE_QUIRK
2627 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2630 Read the PCI windows out of the CNB20LE host bridge. This allows
2631 PCI hotplug to work on systems with the CNB20LE chipset which do
2634 There's no public spec for this chipset, and this functionality
2635 is known to be incomplete.
2637 You should say N unless you know you need this.
2640 bool "ISA bus support on modern systems" if EXPERT
2642 Expose ISA bus device drivers and options available for selection and
2643 configuration. Enable this option if your target machine has an ISA
2644 bus. ISA is an older system, displaced by PCI and newer bus
2645 architectures -- if your target machine is modern, it probably does
2646 not have an ISA bus.
2650 # x86_64 have no ISA slots, but can have ISA-style DMA.
2652 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2655 Enables ISA-style DMA support for devices requiring such controllers.
2663 Find out whether you have ISA slots on your motherboard. ISA is the
2664 name of a bus system, i.e. the way the CPU talks to the other stuff
2665 inside your box. Other bus systems are PCI, EISA, MicroChannel
2666 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2667 newer boards don't support it. If you have ISA, say Y, otherwise N.
2670 tristate "NatSemi SCx200 support"
2672 This provides basic support for National Semiconductor's
2673 (now AMD's) Geode processors. The driver probes for the
2674 PCI-IDs of several on-chip devices, so its a good dependency
2675 for other scx200_* drivers.
2677 If compiled as a module, the driver is named scx200.
2679 config SCx200HR_TIMER
2680 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2684 This driver provides a clocksource built upon the on-chip
2685 27MHz high-resolution timer. Its also a workaround for
2686 NSC Geode SC-1100's buggy TSC, which loses time when the
2687 processor goes idle (as is done by the scheduler). The
2688 other workaround is idle=poll boot option.
2691 bool "One Laptop Per Child support"
2698 Add support for detecting the unique features of the OLPC
2702 bool "OLPC XO-1 Power Management"
2703 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2705 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2708 bool "OLPC XO-1 Real Time Clock"
2709 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2711 Add support for the XO-1 real time clock, which can be used as a
2712 programmable wakeup source.
2715 bool "OLPC XO-1 SCI extras"
2716 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2720 Add support for SCI-based features of the OLPC XO-1 laptop:
2721 - EC-driven system wakeups
2725 - AC adapter status updates
2726 - Battery status updates
2728 config OLPC_XO15_SCI
2729 bool "OLPC XO-1.5 SCI extras"
2730 depends on OLPC && ACPI
2733 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2734 - EC-driven system wakeups
2735 - AC adapter status updates
2736 - Battery status updates
2739 bool "PCEngines ALIX System Support (LED setup)"
2742 This option enables system support for the PCEngines ALIX.
2743 At present this just sets up LEDs for GPIO control on
2744 ALIX2/3/6 boards. However, other system specific setup should
2747 Note: You must still enable the drivers for GPIO and LED support
2748 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2750 Note: You have to set alix.force=1 for boards with Award BIOS.
2753 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2756 This option enables system support for the Soekris Engineering net5501.
2759 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2763 This option enables system support for the Traverse Technologies GEOS.
2766 bool "Technologic Systems TS-5500 platform support"
2768 select CHECK_SIGNATURE
2772 This option enables system support for the Technologic Systems TS-5500.
2778 depends on CPU_SUP_AMD && PCI
2781 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2783 Firmwares often provide initial graphics framebuffers so the BIOS,
2784 bootloader or kernel can show basic video-output during boot for
2785 user-guidance and debugging. Historically, x86 used the VESA BIOS
2786 Extensions and EFI-framebuffers for this, which are mostly limited
2788 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2789 framebuffers so the new generic system-framebuffer drivers can be
2790 used on x86. If the framebuffer is not compatible with the generic
2791 modes, it is advertised as fallback platform framebuffer so legacy
2792 drivers like efifb, vesafb and uvesafb can pick it up.
2793 If this option is not selected, all system framebuffers are always
2794 marked as fallback platform framebuffers as usual.
2796 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2797 not be able to pick up generic system framebuffers if this option
2798 is selected. You are highly encouraged to enable simplefb as
2799 replacement if you select this option. simplefb can correctly deal
2800 with generic system framebuffers. But you should still keep vesafb
2801 and others enabled as fallback if a system framebuffer is
2802 incompatible with simplefb.
2809 menu "Binary Emulations"
2811 config IA32_EMULATION
2812 bool "IA32 Emulation"
2814 select ARCH_WANT_OLD_COMPAT_IPC
2816 select COMPAT_BINFMT_ELF
2817 select COMPAT_OLD_SIGACTION
2819 Include code to run legacy 32-bit programs under a
2820 64-bit kernel. You should likely turn this on, unless you're
2821 100% sure that you don't have any 32-bit programs left.
2824 tristate "IA32 a.out support"
2825 depends on IA32_EMULATION
2828 Support old a.out binaries in the 32bit emulation.
2831 bool "x32 ABI for 64-bit mode"
2834 Include code to run binaries for the x32 native 32-bit ABI
2835 for 64-bit processors. An x32 process gets access to the
2836 full 64-bit register file and wide data path while leaving
2837 pointers at 32 bits for smaller memory footprint.
2839 You will need a recent binutils (2.22 or later) with
2840 elf32_x86_64 support enabled to compile a kernel with this
2845 depends on IA32_EMULATION || X86_32
2847 select OLD_SIGSUSPEND3
2851 depends on IA32_EMULATION || X86_X32
2854 config COMPAT_FOR_U64_ALIGNMENT
2857 config SYSVIPC_COMPAT
2865 config HAVE_ATOMIC_IOMAP
2869 config X86_DEV_DMA_OPS
2872 config HAVE_GENERIC_GUP
2875 source "drivers/firmware/Kconfig"
2877 source "arch/x86/kvm/Kconfig"