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
48 select ARCH_32BIT_OFF_T if X86_32
49 select ARCH_CLOCKSOURCE_DATA
50 select ARCH_CLOCKSOURCE_INIT
51 select ARCH_DISCARD_MEMBLOCK
52 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
53 select ARCH_HAS_DEBUG_VIRTUAL
54 select ARCH_HAS_DEVMEM_IS_ALLOWED
55 select ARCH_HAS_ELF_RANDOMIZE
56 select ARCH_HAS_FAST_MULTIPLIER
57 select ARCH_HAS_FILTER_PGPROT
58 select ARCH_HAS_FORTIFY_SOURCE
59 select ARCH_HAS_GCOV_PROFILE_ALL
60 select ARCH_HAS_KCOV if X86_64
61 select ARCH_HAS_MEMBARRIER_SYNC_CORE
62 select ARCH_HAS_PMEM_API if X86_64
63 select ARCH_HAS_PTE_SPECIAL
64 select ARCH_HAS_REFCOUNT
65 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
66 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
67 select ARCH_HAS_SET_MEMORY
68 select ARCH_HAS_SET_DIRECT_MAP
69 select ARCH_HAS_STRICT_KERNEL_RWX
70 select ARCH_HAS_STRICT_MODULE_RWX
71 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
72 select ARCH_HAS_UBSAN_SANITIZE_ALL
73 select ARCH_HAS_ZONE_DEVICE if X86_64
74 select ARCH_HAVE_NMI_SAFE_CMPXCHG
75 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
76 select ARCH_MIGHT_HAVE_PC_PARPORT
77 select ARCH_MIGHT_HAVE_PC_SERIO
79 select ARCH_SUPPORTS_ACPI
80 select ARCH_SUPPORTS_ATOMIC_RMW
81 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
82 select ARCH_USE_BUILTIN_BSWAP
83 select ARCH_USE_QUEUED_RWLOCKS
84 select ARCH_USE_QUEUED_SPINLOCKS
85 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
86 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
87 select ARCH_WANTS_THP_SWAP if X86_64
88 select BUILDTIME_EXTABLE_SORT
90 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
91 select CLOCKSOURCE_WATCHDOG
92 select DCACHE_WORD_ACCESS
93 select EDAC_ATOMIC_SCRUB
95 select GENERIC_CLOCKEVENTS
96 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
97 select GENERIC_CLOCKEVENTS_MIN_ADJUST
98 select GENERIC_CMOS_UPDATE
99 select GENERIC_CPU_AUTOPROBE
100 select GENERIC_CPU_VULNERABILITIES
101 select GENERIC_EARLY_IOREMAP
102 select GENERIC_FIND_FIRST_BIT
104 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
105 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
106 select GENERIC_IRQ_MIGRATION if SMP
107 select GENERIC_IRQ_PROBE
108 select GENERIC_IRQ_RESERVATION_MODE
109 select GENERIC_IRQ_SHOW
110 select GENERIC_PENDING_IRQ if SMP
111 select GENERIC_SMP_IDLE_THREAD
112 select GENERIC_STRNCPY_FROM_USER
113 select GENERIC_STRNLEN_USER
114 select GENERIC_TIME_VSYSCALL
115 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
116 select HAVE_ACPI_APEI if ACPI
117 select HAVE_ACPI_APEI_NMI if ACPI
118 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
119 select HAVE_ARCH_AUDITSYSCALL
120 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
121 select HAVE_ARCH_JUMP_LABEL
122 select HAVE_ARCH_JUMP_LABEL_RELATIVE
123 select HAVE_ARCH_KASAN if X86_64
124 select HAVE_ARCH_KGDB
125 select HAVE_ARCH_MMAP_RND_BITS if MMU
126 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
127 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
128 select HAVE_ARCH_PREL32_RELOCATIONS
129 select HAVE_ARCH_SECCOMP_FILTER
130 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
131 select HAVE_ARCH_STACKLEAK
132 select HAVE_ARCH_TRACEHOOK
133 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
134 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
135 select HAVE_ARCH_VMAP_STACK if X86_64
136 select HAVE_ARCH_WITHIN_STACK_FRAMES
137 select HAVE_CMPXCHG_DOUBLE
138 select HAVE_CMPXCHG_LOCAL
139 select HAVE_CONTEXT_TRACKING if X86_64
140 select HAVE_COPY_THREAD_TLS
141 select HAVE_C_RECORDMCOUNT
142 select HAVE_DEBUG_KMEMLEAK
143 select HAVE_DMA_CONTIGUOUS
144 select HAVE_DYNAMIC_FTRACE
145 select HAVE_DYNAMIC_FTRACE_WITH_REGS
147 select HAVE_EFFICIENT_UNALIGNED_ACCESS
149 select HAVE_EXIT_THREAD
150 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
151 select HAVE_FTRACE_MCOUNT_RECORD
152 select HAVE_FUNCTION_GRAPH_TRACER
153 select HAVE_FUNCTION_TRACER
154 select HAVE_GCC_PLUGINS
155 select HAVE_HW_BREAKPOINT
157 select HAVE_IOREMAP_PROT
158 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
159 select HAVE_IRQ_TIME_ACCOUNTING
160 select HAVE_KERNEL_BZIP2
161 select HAVE_KERNEL_GZIP
162 select HAVE_KERNEL_LZ4
163 select HAVE_KERNEL_LZMA
164 select HAVE_KERNEL_LZO
165 select HAVE_KERNEL_XZ
167 select HAVE_KPROBES_ON_FTRACE
168 select HAVE_FUNCTION_ERROR_INJECTION
169 select HAVE_KRETPROBES
171 select HAVE_LIVEPATCH if X86_64
172 select HAVE_MEMBLOCK_NODE_MAP
173 select HAVE_MIXED_BREAKPOINTS_REGS
174 select HAVE_MOD_ARCH_SPECIFIC
178 select HAVE_OPTPROBES
179 select HAVE_PCSPKR_PLATFORM
180 select HAVE_PERF_EVENTS
181 select HAVE_PERF_EVENTS_NMI
182 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
184 select HAVE_PERF_REGS
185 select HAVE_PERF_USER_STACK_DUMP
186 select HAVE_RCU_TABLE_FREE if PARAVIRT
187 select HAVE_REGS_AND_STACK_ACCESS_API
188 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
189 select HAVE_FUNCTION_ARG_ACCESS_API
190 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
191 select HAVE_STACK_VALIDATION if X86_64
193 select HAVE_SYSCALL_TRACEPOINTS
194 select HAVE_UNSTABLE_SCHED_CLOCK
195 select HAVE_USER_RETURN_NOTIFIER
196 select HOTPLUG_SMT if SMP
197 select IRQ_FORCED_THREADING
198 select NEED_SG_DMA_LENGTH
199 select PCI_DOMAINS if PCI
200 select PCI_LOCKLESS_CONFIG if PCI
203 select RTC_MC146818_LIB
206 select SYSCTL_EXCEPTION_TRACE
207 select THREAD_INFO_IN_TASK
208 select USER_STACKTRACE_SUPPORT
210 select X86_FEATURE_NAMES if PROC_FS
212 config INSTRUCTION_DECODER
214 depends on KPROBES || PERF_EVENTS || UPROBES
218 default "elf32-i386" if X86_32
219 default "elf64-x86-64" if X86_64
221 config ARCH_DEFCONFIG
223 default "arch/x86/configs/i386_defconfig" if X86_32
224 default "arch/x86/configs/x86_64_defconfig" if X86_64
226 config LOCKDEP_SUPPORT
229 config STACKTRACE_SUPPORT
235 config ARCH_MMAP_RND_BITS_MIN
239 config ARCH_MMAP_RND_BITS_MAX
243 config ARCH_MMAP_RND_COMPAT_BITS_MIN
246 config ARCH_MMAP_RND_COMPAT_BITS_MAX
252 config GENERIC_ISA_DMA
254 depends on ISA_DMA_API
259 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
261 config GENERIC_BUG_RELATIVE_POINTERS
264 config GENERIC_HWEIGHT
267 config ARCH_MAY_HAVE_PC_FDC
269 depends on ISA_DMA_API
271 config GENERIC_CALIBRATE_DELAY
274 config ARCH_HAS_CPU_RELAX
277 config ARCH_HAS_CACHE_LINE_SIZE
280 config ARCH_HAS_FILTER_PGPROT
283 config HAVE_SETUP_PER_CPU_AREA
286 config NEED_PER_CPU_EMBED_FIRST_CHUNK
289 config NEED_PER_CPU_PAGE_FIRST_CHUNK
292 config ARCH_HIBERNATION_POSSIBLE
295 config ARCH_SUSPEND_POSSIBLE
298 config ARCH_WANT_HUGE_PMD_SHARE
301 config ARCH_WANT_GENERAL_HUGETLB
310 config ARCH_SUPPORTS_OPTIMIZED_INLINING
313 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
316 config KASAN_SHADOW_OFFSET
319 default 0xdffffc0000000000
321 config HAVE_INTEL_TXT
323 depends on INTEL_IOMMU && ACPI
327 depends on X86_32 && SMP
331 depends on X86_64 && SMP
333 config X86_32_LAZY_GS
335 depends on X86_32 && !STACKPROTECTOR
337 config ARCH_SUPPORTS_UPROBES
340 config FIX_EARLYCON_MEM
343 config DYNAMIC_PHYSICAL_MASK
346 config PGTABLE_LEVELS
348 default 5 if X86_5LEVEL
353 config CC_HAS_SANE_STACKPROTECTOR
355 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
356 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
358 We have to make sure stack protector is unconditionally disabled if
359 the compiler produces broken code.
361 menu "Processor type and features"
364 bool "DMA memory allocation support" if EXPERT
367 DMA memory allocation support allows devices with less than 32-bit
368 addressing to allocate within the first 16MB of address space.
369 Disable if no such devices will be used.
374 bool "Symmetric multi-processing support"
376 This enables support for systems with more than one CPU. If you have
377 a system with only one CPU, say N. If you have a system with more
380 If you say N here, the kernel will run on uni- and multiprocessor
381 machines, but will use only one CPU of a multiprocessor machine. If
382 you say Y here, the kernel will run on many, but not all,
383 uniprocessor machines. On a uniprocessor machine, the kernel
384 will run faster if you say N here.
386 Note that if you say Y here and choose architecture "586" or
387 "Pentium" under "Processor family", the kernel will not work on 486
388 architectures. Similarly, multiprocessor kernels for the "PPro"
389 architecture may not work on all Pentium based boards.
391 People using multiprocessor machines who say Y here should also say
392 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
393 Management" code will be disabled if you say Y here.
395 See also <file:Documentation/x86/i386/IO-APIC.txt>,
396 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
397 <http://www.tldp.org/docs.html#howto>.
399 If you don't know what to do here, say N.
401 config X86_FEATURE_NAMES
402 bool "Processor feature human-readable names" if EMBEDDED
405 This option compiles in a table of x86 feature bits and corresponding
406 names. This is required to support /proc/cpuinfo and a few kernel
407 messages. You can disable this to save space, at the expense of
408 making those few kernel messages show numeric feature bits instead.
413 bool "Support x2apic"
414 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
416 This enables x2apic support on CPUs that have this feature.
418 This allows 32-bit apic IDs (so it can support very large systems),
419 and accesses the local apic via MSRs not via mmio.
421 If you don't know what to do here, say N.
424 bool "Enable MPS table" if ACPI || SFI
426 depends on X86_LOCAL_APIC
428 For old smp systems that do not have proper acpi support. Newer systems
429 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
433 depends on X86_GOLDFISH
436 bool "Avoid speculative indirect branches in kernel"
438 select STACK_VALIDATION if HAVE_STACK_VALIDATION
440 Compile kernel with the retpoline compiler options to guard against
441 kernel-to-user data leaks by avoiding speculative indirect
442 branches. Requires a compiler with -mindirect-branch=thunk-extern
443 support for full protection. The kernel may run slower.
445 config X86_CPU_RESCTRL
446 bool "x86 CPU resource control support"
447 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
450 Enable x86 CPU resource control support.
452 Provide support for the allocation and monitoring of system resources
455 Intel calls this Intel Resource Director Technology
456 (Intel(R) RDT). More information about RDT can be found in the
457 Intel x86 Architecture Software Developer Manual.
459 AMD calls this AMD Platform Quality of Service (AMD QoS).
460 More information about AMD QoS can be found in the AMD64 Technology
461 Platform Quality of Service Extensions manual.
467 bool "Support for big SMP systems with more than 8 CPUs"
470 This option is needed for the systems that have more than 8 CPUs
472 config X86_EXTENDED_PLATFORM
473 bool "Support for extended (non-PC) x86 platforms"
476 If you disable this option then the kernel will only support
477 standard PC platforms. (which covers the vast majority of
480 If you enable this option then you'll be able to select support
481 for the following (non-PC) 32 bit x86 platforms:
482 Goldfish (Android emulator)
485 SGI 320/540 (Visual Workstation)
486 STA2X11-based (e.g. Northville)
487 Moorestown MID devices
489 If you have one of these systems, or if you want to build a
490 generic distribution kernel, say Y here - otherwise say N.
494 config X86_EXTENDED_PLATFORM
495 bool "Support for extended (non-PC) x86 platforms"
498 If you disable this option then the kernel will only support
499 standard PC platforms. (which covers the vast majority of
502 If you enable this option then you'll be able to select support
503 for the following (non-PC) 64 bit x86 platforms:
508 If you have one of these systems, or if you want to build a
509 generic distribution kernel, say Y here - otherwise say N.
511 # This is an alphabetically sorted list of 64 bit extended platforms
512 # Please maintain the alphabetic order if and when there are additions
514 bool "Numascale NumaChip"
516 depends on X86_EXTENDED_PLATFORM
519 depends on X86_X2APIC
520 depends on PCI_MMCONFIG
522 Adds support for Numascale NumaChip large-SMP systems. Needed to
523 enable more than ~168 cores.
524 If you don't have one of these, you should say N here.
528 select HYPERVISOR_GUEST
530 depends on X86_64 && PCI
531 depends on X86_EXTENDED_PLATFORM
534 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
535 supposed to run on these EM64T-based machines. Only choose this option
536 if you have one of these machines.
539 bool "SGI Ultraviolet"
541 depends on X86_EXTENDED_PLATFORM
544 depends on X86_X2APIC
547 This option is needed in order to support SGI Ultraviolet systems.
548 If you don't have one of these, you should say N here.
550 # Following is an alphabetically sorted list of 32 bit extended platforms
551 # Please maintain the alphabetic order if and when there are additions
554 bool "Goldfish (Virtual Platform)"
555 depends on X86_EXTENDED_PLATFORM
557 Enable support for the Goldfish virtual platform used primarily
558 for Android development. Unless you are building for the Android
559 Goldfish emulator say N here.
562 bool "CE4100 TV platform"
564 depends on PCI_GODIRECT
565 depends on X86_IO_APIC
567 depends on X86_EXTENDED_PLATFORM
568 select X86_REBOOTFIXUPS
570 select OF_EARLY_FLATTREE
572 Select for the Intel CE media processor (CE4100) SOC.
573 This option compiles in support for the CE4100 SOC for settop
574 boxes and media devices.
577 bool "Intel MID platform support"
578 depends on X86_EXTENDED_PLATFORM
579 depends on X86_PLATFORM_DEVICES
581 depends on X86_64 || (PCI_GOANY && X86_32)
582 depends on X86_IO_APIC
588 select MFD_INTEL_MSIC
590 Select to build a kernel capable of supporting Intel MID (Mobile
591 Internet Device) platform systems which do not have the PCI legacy
592 interfaces. If you are building for a PC class system say N here.
594 Intel MID platforms are based on an Intel processor and chipset which
595 consume less power than most of the x86 derivatives.
597 config X86_INTEL_QUARK
598 bool "Intel Quark platform support"
600 depends on X86_EXTENDED_PLATFORM
601 depends on X86_PLATFORM_DEVICES
605 depends on X86_IO_APIC
610 Select to include support for Quark X1000 SoC.
611 Say Y here if you have a Quark based system such as the Arduino
612 compatible Intel Galileo.
614 config X86_INTEL_LPSS
615 bool "Intel Low Power Subsystem Support"
616 depends on X86 && ACPI && PCI
621 Select to build support for Intel Low Power Subsystem such as
622 found on Intel Lynxpoint PCH. Selecting this option enables
623 things like clock tree (common clock framework) and pincontrol
624 which are needed by the LPSS peripheral drivers.
626 config X86_AMD_PLATFORM_DEVICE
627 bool "AMD ACPI2Platform devices support"
632 Select to interpret AMD specific ACPI device to platform device
633 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
634 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
635 implemented under PINCTRL subsystem.
638 tristate "Intel SoC IOSF Sideband support for SoC platforms"
641 This option enables sideband register access support for Intel SoC
642 platforms. On these platforms the IOSF sideband is used in lieu of
643 MSR's for some register accesses, mostly but not limited to thermal
644 and power. Drivers may query the availability of this device to
645 determine if they need the sideband in order to work on these
646 platforms. The sideband is available on the following SoC products.
647 This list is not meant to be exclusive.
652 You should say Y if you are running a kernel on one of these SoC's.
654 config IOSF_MBI_DEBUG
655 bool "Enable IOSF sideband access through debugfs"
656 depends on IOSF_MBI && DEBUG_FS
658 Select this option to expose the IOSF sideband access registers (MCR,
659 MDR, MCRX) through debugfs to write and read register information from
660 different units on the SoC. This is most useful for obtaining device
661 state information for debug and analysis. As this is a general access
662 mechanism, users of this option would have specific knowledge of the
663 device they want to access.
665 If you don't require the option or are in doubt, say N.
668 bool "RDC R-321x SoC"
670 depends on X86_EXTENDED_PLATFORM
672 select X86_REBOOTFIXUPS
674 This option is needed for RDC R-321x system-on-chip, also known
676 If you don't have one of these chips, you should say N here.
678 config X86_32_NON_STANDARD
679 bool "Support non-standard 32-bit SMP architectures"
680 depends on X86_32 && SMP
681 depends on X86_EXTENDED_PLATFORM
683 This option compiles in the bigsmp and STA2X11 default
684 subarchitectures. It is intended for a generic binary
685 kernel. If you select them all, kernel will probe it one by
686 one and will fallback to default.
688 # Alphabetically sorted list of Non standard 32 bit platforms
690 config X86_SUPPORTS_MEMORY_FAILURE
692 # MCE code calls memory_failure():
694 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
695 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
696 depends on X86_64 || !SPARSEMEM
697 select ARCH_SUPPORTS_MEMORY_FAILURE
700 bool "STA2X11 Companion Chip Support"
701 depends on X86_32_NON_STANDARD && PCI
702 select ARCH_HAS_PHYS_TO_DMA
707 This adds support for boards based on the STA2X11 IO-Hub,
708 a.k.a. "ConneXt". The chip is used in place of the standard
709 PC chipset, so all "standard" peripherals are missing. If this
710 option is selected the kernel will still be able to boot on
711 standard PC machines.
714 tristate "Eurobraille/Iris poweroff module"
717 The Iris machines from EuroBraille do not have APM or ACPI support
718 to shut themselves down properly. A special I/O sequence is
719 needed to do so, which is what this module does at
722 This is only for Iris machines from EuroBraille.
726 config SCHED_OMIT_FRAME_POINTER
728 prompt "Single-depth WCHAN output"
731 Calculate simpler /proc/<PID>/wchan values. If this option
732 is disabled then wchan values will recurse back to the
733 caller function. This provides more accurate wchan values,
734 at the expense of slightly more scheduling overhead.
736 If in doubt, say "Y".
738 menuconfig HYPERVISOR_GUEST
739 bool "Linux guest support"
741 Say Y here to enable options for running Linux under various hyper-
742 visors. This option enables basic hypervisor detection and platform
745 If you say N, all options in this submenu will be skipped and
746 disabled, and Linux guest support won't be built in.
751 bool "Enable paravirtualization code"
753 This changes the kernel so it can modify itself when it is run
754 under a hypervisor, potentially improving performance significantly
755 over full virtualization. However, when run without a hypervisor
756 the kernel is theoretically slower and slightly larger.
761 config PARAVIRT_DEBUG
762 bool "paravirt-ops debugging"
763 depends on PARAVIRT && DEBUG_KERNEL
765 Enable to debug paravirt_ops internals. Specifically, BUG if
766 a paravirt_op is missing when it is called.
768 config PARAVIRT_SPINLOCKS
769 bool "Paravirtualization layer for spinlocks"
770 depends on PARAVIRT && SMP
772 Paravirtualized spinlocks allow a pvops backend to replace the
773 spinlock implementation with something virtualization-friendly
774 (for example, block the virtual CPU rather than spinning).
776 It has a minimal impact on native kernels and gives a nice performance
777 benefit on paravirtualized KVM / Xen kernels.
779 If you are unsure how to answer this question, answer Y.
781 source "arch/x86/xen/Kconfig"
784 bool "KVM Guest support (including kvmclock)"
786 select PARAVIRT_CLOCK
789 This option enables various optimizations for running under the KVM
790 hypervisor. It includes a paravirtualized clock, so that instead
791 of relying on a PIT (or probably other) emulation by the
792 underlying device model, the host provides the guest with
793 timing infrastructure such as time of day, and system time
796 bool "Support for running PVH guests"
798 This option enables the PVH entry point for guest virtual machines
799 as specified in the x86/HVM direct boot ABI.
802 bool "Enable debug information for KVM Guests in debugfs"
803 depends on KVM_GUEST && DEBUG_FS
805 This option enables collection of various statistics for KVM guest.
806 Statistics are displayed in debugfs filesystem. Enabling this option
807 may incur significant overhead.
809 config PARAVIRT_TIME_ACCOUNTING
810 bool "Paravirtual steal time accounting"
813 Select this option to enable fine granularity task steal time
814 accounting. Time spent executing other tasks in parallel with
815 the current vCPU is discounted from the vCPU power. To account for
816 that, there can be a small performance impact.
818 If in doubt, say N here.
820 config PARAVIRT_CLOCK
823 config JAILHOUSE_GUEST
824 bool "Jailhouse non-root cell support"
825 depends on X86_64 && PCI
828 This option allows to run Linux as guest in a Jailhouse non-root
829 cell. You can leave this option disabled if you only want to start
830 Jailhouse and run Linux afterwards in the root cell.
832 endif #HYPERVISOR_GUEST
834 source "arch/x86/Kconfig.cpu"
838 prompt "HPET Timer Support" if X86_32
840 Use the IA-PC HPET (High Precision Event Timer) to manage
841 time in preference to the PIT and RTC, if a HPET is
843 HPET is the next generation timer replacing legacy 8254s.
844 The HPET provides a stable time base on SMP
845 systems, unlike the TSC, but it is more expensive to access,
846 as it is off-chip. The interface used is documented
847 in the HPET spec, revision 1.
849 You can safely choose Y here. However, HPET will only be
850 activated if the platform and the BIOS support this feature.
851 Otherwise the 8254 will be used for timing services.
853 Choose N to continue using the legacy 8254 timer.
855 config HPET_EMULATE_RTC
857 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
860 def_bool y if X86_INTEL_MID
861 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
863 depends on X86_INTEL_MID && SFI
865 APB timer is the replacement for 8254, HPET on X86 MID platforms.
866 The APBT provides a stable time base on SMP
867 systems, unlike the TSC, but it is more expensive to access,
868 as it is off-chip. APB timers are always running regardless of CPU
869 C states, they are used as per CPU clockevent device when possible.
871 # Mark as expert because too many people got it wrong.
872 # The code disables itself when not needed.
875 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
876 bool "Enable DMI scanning" if EXPERT
878 Enabled scanning of DMI to identify machine quirks. Say Y
879 here unless you have verified that your setup is not
880 affected by entries in the DMI blacklist. Required by PNP
884 bool "Old AMD GART IOMMU support"
887 depends on X86_64 && PCI && AMD_NB
889 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
890 GART based hardware IOMMUs.
892 The GART supports full DMA access for devices with 32-bit access
893 limitations, on systems with more than 3 GB. This is usually needed
894 for USB, sound, many IDE/SATA chipsets and some other devices.
896 Newer systems typically have a modern AMD IOMMU, supported via
897 the CONFIG_AMD_IOMMU=y config option.
899 In normal configurations this driver is only active when needed:
900 there's more than 3 GB of memory and the system contains a
901 32-bit limited device.
906 bool "IBM Calgary IOMMU support"
909 depends on X86_64 && PCI
911 Support for hardware IOMMUs in IBM's xSeries x366 and x460
912 systems. Needed to run systems with more than 3GB of memory
913 properly with 32-bit PCI devices that do not support DAC
914 (Double Address Cycle). Calgary also supports bus level
915 isolation, where all DMAs pass through the IOMMU. This
916 prevents them from going anywhere except their intended
917 destination. This catches hard-to-find kernel bugs and
918 mis-behaving drivers and devices that do not use the DMA-API
919 properly to set up their DMA buffers. The IOMMU can be
920 turned off at boot time with the iommu=off parameter.
921 Normally the kernel will make the right choice by itself.
924 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
926 prompt "Should Calgary be enabled by default?"
927 depends on CALGARY_IOMMU
929 Should Calgary be enabled by default? if you choose 'y', Calgary
930 will be used (if it exists). If you choose 'n', Calgary will not be
931 used even if it exists. If you choose 'n' and would like to use
932 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
936 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
937 depends on X86_64 && SMP && DEBUG_KERNEL
938 select CPUMASK_OFFSTACK
940 Enable maximum number of CPUS and NUMA Nodes for this architecture.
944 # The maximum number of CPUs supported:
946 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
947 # and which can be configured interactively in the
948 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
950 # The ranges are different on 32-bit and 64-bit kernels, depending on
951 # hardware capabilities and scalability features of the kernel.
953 # ( If MAXSMP is enabled we just use the highest possible value and disable
954 # interactive configuration. )
957 config NR_CPUS_RANGE_BEGIN
959 default NR_CPUS_RANGE_END if MAXSMP
963 config NR_CPUS_RANGE_END
966 default 64 if SMP && X86_BIGSMP
967 default 8 if SMP && !X86_BIGSMP
970 config NR_CPUS_RANGE_END
973 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
974 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
977 config NR_CPUS_DEFAULT
980 default 32 if X86_BIGSMP
984 config NR_CPUS_DEFAULT
987 default 8192 if MAXSMP
992 int "Maximum number of CPUs" if SMP && !MAXSMP
993 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
994 default NR_CPUS_DEFAULT
996 This allows you to specify the maximum number of CPUs which this
997 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
998 supported value is 8192, otherwise the maximum value is 512. The
999 minimum value which makes sense is 2.
1001 This is purely to save memory: each supported CPU adds about 8KB
1002 to the kernel image.
1009 prompt "Multi-core scheduler support"
1012 Multi-core scheduler support improves the CPU scheduler's decision
1013 making when dealing with multi-core CPU chips at a cost of slightly
1014 increased overhead in some places. If unsure say N here.
1016 config SCHED_MC_PRIO
1017 bool "CPU core priorities scheduler support"
1018 depends on SCHED_MC && CPU_SUP_INTEL
1019 select X86_INTEL_PSTATE
1023 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1024 core ordering determined at manufacturing time, which allows
1025 certain cores to reach higher turbo frequencies (when running
1026 single threaded workloads) than others.
1028 Enabling this kernel feature teaches the scheduler about
1029 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1030 scheduler's CPU selection logic accordingly, so that higher
1031 overall system performance can be achieved.
1033 This feature will have no effect on CPUs without this feature.
1035 If unsure say Y here.
1039 depends on !SMP && X86_LOCAL_APIC
1042 bool "Local APIC support on uniprocessors" if !PCI_MSI
1044 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1046 A local APIC (Advanced Programmable Interrupt Controller) is an
1047 integrated interrupt controller in the CPU. If you have a single-CPU
1048 system which has a processor with a local APIC, you can say Y here to
1049 enable and use it. If you say Y here even though your machine doesn't
1050 have a local APIC, then the kernel will still run with no slowdown at
1051 all. The local APIC supports CPU-generated self-interrupts (timer,
1052 performance counters), and the NMI watchdog which detects hard
1055 config X86_UP_IOAPIC
1056 bool "IO-APIC support on uniprocessors"
1057 depends on X86_UP_APIC
1059 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1060 SMP-capable replacement for PC-style interrupt controllers. Most
1061 SMP systems and many recent uniprocessor systems have one.
1063 If you have a single-CPU system with an IO-APIC, you can say Y here
1064 to use it. If you say Y here even though your machine doesn't have
1065 an IO-APIC, then the kernel will still run with no slowdown at all.
1067 config X86_LOCAL_APIC
1069 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1070 select IRQ_DOMAIN_HIERARCHY
1071 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1075 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1077 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1078 bool "Reroute for broken boot IRQs"
1079 depends on X86_IO_APIC
1081 This option enables a workaround that fixes a source of
1082 spurious interrupts. This is recommended when threaded
1083 interrupt handling is used on systems where the generation of
1084 superfluous "boot interrupts" cannot be disabled.
1086 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1087 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1088 kernel does during interrupt handling). On chipsets where this
1089 boot IRQ generation cannot be disabled, this workaround keeps
1090 the original IRQ line masked so that only the equivalent "boot
1091 IRQ" is delivered to the CPUs. The workaround also tells the
1092 kernel to set up the IRQ handler on the boot IRQ line. In this
1093 way only one interrupt is delivered to the kernel. Otherwise
1094 the spurious second interrupt may cause the kernel to bring
1095 down (vital) interrupt lines.
1097 Only affects "broken" chipsets. Interrupt sharing may be
1098 increased on these systems.
1101 bool "Machine Check / overheating reporting"
1102 select GENERIC_ALLOCATOR
1105 Machine Check support allows the processor to notify the
1106 kernel if it detects a problem (e.g. overheating, data corruption).
1107 The action the kernel takes depends on the severity of the problem,
1108 ranging from warning messages to halting the machine.
1110 config X86_MCELOG_LEGACY
1111 bool "Support for deprecated /dev/mcelog character device"
1114 Enable support for /dev/mcelog which is needed by the old mcelog
1115 userspace logging daemon. Consider switching to the new generation
1118 config X86_MCE_INTEL
1120 prompt "Intel MCE features"
1121 depends on X86_MCE && X86_LOCAL_APIC
1123 Additional support for intel specific MCE features such as
1124 the thermal monitor.
1128 prompt "AMD MCE features"
1129 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1131 Additional support for AMD specific MCE features such as
1132 the DRAM Error Threshold.
1134 config X86_ANCIENT_MCE
1135 bool "Support for old Pentium 5 / WinChip machine checks"
1136 depends on X86_32 && X86_MCE
1138 Include support for machine check handling on old Pentium 5 or WinChip
1139 systems. These typically need to be enabled explicitly on the command
1142 config X86_MCE_THRESHOLD
1143 depends on X86_MCE_AMD || X86_MCE_INTEL
1146 config X86_MCE_INJECT
1147 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1148 tristate "Machine check injector support"
1150 Provide support for injecting machine checks for testing purposes.
1151 If you don't know what a machine check is and you don't do kernel
1152 QA it is safe to say n.
1154 config X86_THERMAL_VECTOR
1156 depends on X86_MCE_INTEL
1158 source "arch/x86/events/Kconfig"
1160 config X86_LEGACY_VM86
1161 bool "Legacy VM86 support"
1164 This option allows user programs to put the CPU into V8086
1165 mode, which is an 80286-era approximation of 16-bit real mode.
1167 Some very old versions of X and/or vbetool require this option
1168 for user mode setting. Similarly, DOSEMU will use it if
1169 available to accelerate real mode DOS programs. However, any
1170 recent version of DOSEMU, X, or vbetool should be fully
1171 functional even without kernel VM86 support, as they will all
1172 fall back to software emulation. Nevertheless, if you are using
1173 a 16-bit DOS program where 16-bit performance matters, vm86
1174 mode might be faster than emulation and you might want to
1177 Note that any app that works on a 64-bit kernel is unlikely to
1178 need this option, as 64-bit kernels don't, and can't, support
1179 V8086 mode. This option is also unrelated to 16-bit protected
1180 mode and is not needed to run most 16-bit programs under Wine.
1182 Enabling this option increases the complexity of the kernel
1183 and slows down exception handling a tiny bit.
1185 If unsure, say N here.
1189 default X86_LEGACY_VM86
1192 bool "Enable support for 16-bit segments" if EXPERT
1194 depends on MODIFY_LDT_SYSCALL
1196 This option is required by programs like Wine to run 16-bit
1197 protected mode legacy code on x86 processors. Disabling
1198 this option saves about 300 bytes on i386, or around 6K text
1199 plus 16K runtime memory on x86-64,
1203 depends on X86_16BIT && X86_32
1207 depends on X86_16BIT && X86_64
1209 config X86_VSYSCALL_EMULATION
1210 bool "Enable vsyscall emulation" if EXPERT
1214 This enables emulation of the legacy vsyscall page. Disabling
1215 it is roughly equivalent to booting with vsyscall=none, except
1216 that it will also disable the helpful warning if a program
1217 tries to use a vsyscall. With this option set to N, offending
1218 programs will just segfault, citing addresses of the form
1221 This option is required by many programs built before 2013, and
1222 care should be used even with newer programs if set to N.
1224 Disabling this option saves about 7K of kernel size and
1225 possibly 4K of additional runtime pagetable memory.
1228 tristate "Toshiba Laptop support"
1231 This adds a driver to safely access the System Management Mode of
1232 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1233 not work on models with a Phoenix BIOS. The System Management Mode
1234 is used to set the BIOS and power saving options on Toshiba portables.
1236 For information on utilities to make use of this driver see the
1237 Toshiba Linux utilities web site at:
1238 <http://www.buzzard.org.uk/toshiba/>.
1240 Say Y if you intend to run this kernel on a Toshiba portable.
1244 tristate "Dell i8k legacy laptop support"
1246 select SENSORS_DELL_SMM
1248 This option enables legacy /proc/i8k userspace interface in hwmon
1249 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1250 temperature and allows controlling fan speeds of Dell laptops via
1251 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1252 it reports also power and hotkey status. For fan speed control is
1253 needed userspace package i8kutils.
1255 Say Y if you intend to run this kernel on old Dell laptops or want to
1256 use userspace package i8kutils.
1259 config X86_REBOOTFIXUPS
1260 bool "Enable X86 board specific fixups for reboot"
1263 This enables chipset and/or board specific fixups to be done
1264 in order to get reboot to work correctly. This is only needed on
1265 some combinations of hardware and BIOS. The symptom, for which
1266 this config is intended, is when reboot ends with a stalled/hung
1269 Currently, the only fixup is for the Geode machines using
1270 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1272 Say Y if you want to enable the fixup. Currently, it's safe to
1273 enable this option even if you don't need it.
1277 bool "CPU microcode loading support"
1279 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1282 If you say Y here, you will be able to update the microcode on
1283 Intel and AMD processors. The Intel support is for the IA32 family,
1284 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1285 AMD support is for families 0x10 and later. You will obviously need
1286 the actual microcode binary data itself which is not shipped with
1289 The preferred method to load microcode from a detached initrd is described
1290 in Documentation/x86/microcode.txt. For that you need to enable
1291 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1292 initrd for microcode blobs.
1294 In addition, you can build the microcode into the kernel. For that you
1295 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1298 config MICROCODE_INTEL
1299 bool "Intel microcode loading support"
1300 depends on MICROCODE
1304 This options enables microcode patch loading support for Intel
1307 For the current Intel microcode data package go to
1308 <https://downloadcenter.intel.com> and search for
1309 'Linux Processor Microcode Data File'.
1311 config MICROCODE_AMD
1312 bool "AMD microcode loading support"
1313 depends on MICROCODE
1316 If you select this option, microcode patch loading support for AMD
1317 processors will be enabled.
1319 config MICROCODE_OLD_INTERFACE
1320 bool "Ancient loading interface (DEPRECATED)"
1322 depends on MICROCODE
1324 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1325 which was used by userspace tools like iucode_tool and microcode.ctl.
1326 It is inadequate because it runs too late to be able to properly
1327 load microcode on a machine and it needs special tools. Instead, you
1328 should've switched to the early loading method with the initrd or
1329 builtin microcode by now: Documentation/x86/microcode.txt
1332 tristate "/dev/cpu/*/msr - Model-specific register support"
1334 This device gives privileged processes access to the x86
1335 Model-Specific Registers (MSRs). It is a character device with
1336 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1337 MSR accesses are directed to a specific CPU on multi-processor
1341 tristate "/dev/cpu/*/cpuid - CPU information support"
1343 This device gives processes access to the x86 CPUID instruction to
1344 be executed on a specific processor. It is a character device
1345 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1349 prompt "High Memory Support"
1356 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1357 However, the address space of 32-bit x86 processors is only 4
1358 Gigabytes large. That means that, if you have a large amount of
1359 physical memory, not all of it can be "permanently mapped" by the
1360 kernel. The physical memory that's not permanently mapped is called
1363 If you are compiling a kernel which will never run on a machine with
1364 more than 1 Gigabyte total physical RAM, answer "off" here (default
1365 choice and suitable for most users). This will result in a "3GB/1GB"
1366 split: 3GB are mapped so that each process sees a 3GB virtual memory
1367 space and the remaining part of the 4GB virtual memory space is used
1368 by the kernel to permanently map as much physical memory as
1371 If the machine has between 1 and 4 Gigabytes physical RAM, then
1374 If more than 4 Gigabytes is used then answer "64GB" here. This
1375 selection turns Intel PAE (Physical Address Extension) mode on.
1376 PAE implements 3-level paging on IA32 processors. PAE is fully
1377 supported by Linux, PAE mode is implemented on all recent Intel
1378 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1379 then the kernel will not boot on CPUs that don't support PAE!
1381 The actual amount of total physical memory will either be
1382 auto detected or can be forced by using a kernel command line option
1383 such as "mem=256M". (Try "man bootparam" or see the documentation of
1384 your boot loader (lilo or loadlin) about how to pass options to the
1385 kernel at boot time.)
1387 If unsure, say "off".
1392 Select this if you have a 32-bit processor and between 1 and 4
1393 gigabytes of physical RAM.
1397 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1400 Select this if you have a 32-bit processor and more than 4
1401 gigabytes of physical RAM.
1406 prompt "Memory split" if EXPERT
1410 Select the desired split between kernel and user memory.
1412 If the address range available to the kernel is less than the
1413 physical memory installed, the remaining memory will be available
1414 as "high memory". Accessing high memory is a little more costly
1415 than low memory, as it needs to be mapped into the kernel first.
1416 Note that increasing the kernel address space limits the range
1417 available to user programs, making the address space there
1418 tighter. Selecting anything other than the default 3G/1G split
1419 will also likely make your kernel incompatible with binary-only
1422 If you are not absolutely sure what you are doing, leave this
1426 bool "3G/1G user/kernel split"
1427 config VMSPLIT_3G_OPT
1429 bool "3G/1G user/kernel split (for full 1G low memory)"
1431 bool "2G/2G user/kernel split"
1432 config VMSPLIT_2G_OPT
1434 bool "2G/2G user/kernel split (for full 2G low memory)"
1436 bool "1G/3G user/kernel split"
1441 default 0xB0000000 if VMSPLIT_3G_OPT
1442 default 0x80000000 if VMSPLIT_2G
1443 default 0x78000000 if VMSPLIT_2G_OPT
1444 default 0x40000000 if VMSPLIT_1G
1450 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1453 bool "PAE (Physical Address Extension) Support"
1454 depends on X86_32 && !HIGHMEM4G
1455 select PHYS_ADDR_T_64BIT
1458 PAE is required for NX support, and furthermore enables
1459 larger swapspace support for non-overcommit purposes. It
1460 has the cost of more pagetable lookup overhead, and also
1461 consumes more pagetable space per process.
1464 bool "Enable 5-level page tables support"
1465 select DYNAMIC_MEMORY_LAYOUT
1466 select SPARSEMEM_VMEMMAP
1469 5-level paging enables access to larger address space:
1470 upto 128 PiB of virtual address space and 4 PiB of
1471 physical address space.
1473 It will be supported by future Intel CPUs.
1475 A kernel with the option enabled can be booted on machines that
1476 support 4- or 5-level paging.
1478 See Documentation/x86/x86_64/5level-paging.txt for more
1483 config X86_DIRECT_GBPAGES
1485 depends on X86_64 && !DEBUG_PAGEALLOC
1487 Certain kernel features effectively disable kernel
1488 linear 1 GB mappings (even if the CPU otherwise
1489 supports them), so don't confuse the user by printing
1490 that we have them enabled.
1492 config X86_CPA_STATISTICS
1493 bool "Enable statistic for Change Page Attribute"
1496 Expose statistics about the Change Page Attribute mechanims, which
1497 helps to determine the effectiveness of preserving large and huge
1498 page mappings when mapping protections are changed.
1500 config ARCH_HAS_MEM_ENCRYPT
1503 config AMD_MEM_ENCRYPT
1504 bool "AMD Secure Memory Encryption (SME) support"
1505 depends on X86_64 && CPU_SUP_AMD
1506 select DYNAMIC_PHYSICAL_MASK
1507 select ARCH_USE_MEMREMAP_PROT
1509 Say yes to enable support for the encryption of system memory.
1510 This requires an AMD processor that supports Secure Memory
1513 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1514 bool "Activate AMD Secure Memory Encryption (SME) by default"
1516 depends on AMD_MEM_ENCRYPT
1518 Say yes to have system memory encrypted by default if running on
1519 an AMD processor that supports Secure Memory Encryption (SME).
1521 If set to Y, then the encryption of system memory can be
1522 deactivated with the mem_encrypt=off command line option.
1524 If set to N, then the encryption of system memory can be
1525 activated with the mem_encrypt=on command line option.
1527 # Common NUMA Features
1529 bool "Numa Memory Allocation and Scheduler Support"
1531 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1532 default y if X86_BIGSMP
1534 Enable NUMA (Non Uniform Memory Access) support.
1536 The kernel will try to allocate memory used by a CPU on the
1537 local memory controller of the CPU and add some more
1538 NUMA awareness to the kernel.
1540 For 64-bit this is recommended if the system is Intel Core i7
1541 (or later), AMD Opteron, or EM64T NUMA.
1543 For 32-bit this is only needed if you boot a 32-bit
1544 kernel on a 64-bit NUMA platform.
1546 Otherwise, you should say N.
1550 prompt "Old style AMD Opteron NUMA detection"
1551 depends on X86_64 && NUMA && PCI
1553 Enable AMD NUMA node topology detection. You should say Y here if
1554 you have a multi processor AMD system. This uses an old method to
1555 read the NUMA configuration directly from the builtin Northbridge
1556 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1557 which also takes priority if both are compiled in.
1559 config X86_64_ACPI_NUMA
1561 prompt "ACPI NUMA detection"
1562 depends on X86_64 && NUMA && ACPI && PCI
1565 Enable ACPI SRAT based node topology detection.
1567 # Some NUMA nodes have memory ranges that span
1568 # other nodes. Even though a pfn is valid and
1569 # between a node's start and end pfns, it may not
1570 # reside on that node. See memmap_init_zone()
1572 config NODES_SPAN_OTHER_NODES
1574 depends on X86_64_ACPI_NUMA
1577 bool "NUMA emulation"
1580 Enable NUMA emulation. A flat machine will be split
1581 into virtual nodes when booted with "numa=fake=N", where N is the
1582 number of nodes. This is only useful for debugging.
1585 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1587 default "10" if MAXSMP
1588 default "6" if X86_64
1590 depends on NEED_MULTIPLE_NODES
1592 Specify the maximum number of NUMA Nodes available on the target
1593 system. Increases memory reserved to accommodate various tables.
1595 config ARCH_HAVE_MEMORY_PRESENT
1597 depends on X86_32 && DISCONTIGMEM
1599 config ARCH_FLATMEM_ENABLE
1601 depends on X86_32 && !NUMA
1603 config ARCH_DISCONTIGMEM_ENABLE
1605 depends on NUMA && X86_32
1608 config ARCH_SPARSEMEM_ENABLE
1610 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1611 select SPARSEMEM_STATIC if X86_32
1612 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1614 config ARCH_SPARSEMEM_DEFAULT
1615 def_bool X86_64 || (NUMA && X86_32)
1617 config ARCH_SELECT_MEMORY_MODEL
1619 depends on ARCH_SPARSEMEM_ENABLE
1621 config ARCH_MEMORY_PROBE
1622 bool "Enable sysfs memory/probe interface"
1623 depends on X86_64 && MEMORY_HOTPLUG
1625 This option enables a sysfs memory/probe interface for testing.
1626 See Documentation/memory-hotplug.txt for more information.
1627 If you are unsure how to answer this question, answer N.
1629 config ARCH_PROC_KCORE_TEXT
1631 depends on X86_64 && PROC_KCORE
1633 config ILLEGAL_POINTER_VALUE
1636 default 0xdead000000000000 if X86_64
1638 config X86_PMEM_LEGACY_DEVICE
1641 config X86_PMEM_LEGACY
1642 tristate "Support non-standard NVDIMMs and ADR protected memory"
1643 depends on PHYS_ADDR_T_64BIT
1645 select X86_PMEM_LEGACY_DEVICE
1648 Treat memory marked using the non-standard e820 type of 12 as used
1649 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1650 The kernel will offer these regions to the 'pmem' driver so
1651 they can be used for persistent storage.
1656 bool "Allocate 3rd-level pagetables from highmem"
1659 The VM uses one page table entry for each page of physical memory.
1660 For systems with a lot of RAM, this can be wasteful of precious
1661 low memory. Setting this option will put user-space page table
1662 entries in high memory.
1664 config X86_CHECK_BIOS_CORRUPTION
1665 bool "Check for low memory corruption"
1667 Periodically check for memory corruption in low memory, which
1668 is suspected to be caused by BIOS. Even when enabled in the
1669 configuration, it is disabled at runtime. Enable it by
1670 setting "memory_corruption_check=1" on the kernel command
1671 line. By default it scans the low 64k of memory every 60
1672 seconds; see the memory_corruption_check_size and
1673 memory_corruption_check_period parameters in
1674 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1676 When enabled with the default parameters, this option has
1677 almost no overhead, as it reserves a relatively small amount
1678 of memory and scans it infrequently. It both detects corruption
1679 and prevents it from affecting the running system.
1681 It is, however, intended as a diagnostic tool; if repeatable
1682 BIOS-originated corruption always affects the same memory,
1683 you can use memmap= to prevent the kernel from using that
1686 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1687 bool "Set the default setting of memory_corruption_check"
1688 depends on X86_CHECK_BIOS_CORRUPTION
1691 Set whether the default state of memory_corruption_check is
1694 config X86_RESERVE_LOW
1695 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1699 Specify the amount of low memory to reserve for the BIOS.
1701 The first page contains BIOS data structures that the kernel
1702 must not use, so that page must always be reserved.
1704 By default we reserve the first 64K of physical RAM, as a
1705 number of BIOSes are known to corrupt that memory range
1706 during events such as suspend/resume or monitor cable
1707 insertion, so it must not be used by the kernel.
1709 You can set this to 4 if you are absolutely sure that you
1710 trust the BIOS to get all its memory reservations and usages
1711 right. If you know your BIOS have problems beyond the
1712 default 64K area, you can set this to 640 to avoid using the
1713 entire low memory range.
1715 If you have doubts about the BIOS (e.g. suspend/resume does
1716 not work or there's kernel crashes after certain hardware
1717 hotplug events) then you might want to enable
1718 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1719 typical corruption patterns.
1721 Leave this to the default value of 64 if you are unsure.
1723 config MATH_EMULATION
1725 depends on MODIFY_LDT_SYSCALL
1726 prompt "Math emulation" if X86_32
1728 Linux can emulate a math coprocessor (used for floating point
1729 operations) if you don't have one. 486DX and Pentium processors have
1730 a math coprocessor built in, 486SX and 386 do not, unless you added
1731 a 487DX or 387, respectively. (The messages during boot time can
1732 give you some hints here ["man dmesg"].) Everyone needs either a
1733 coprocessor or this emulation.
1735 If you don't have a math coprocessor, you need to say Y here; if you
1736 say Y here even though you have a coprocessor, the coprocessor will
1737 be used nevertheless. (This behavior can be changed with the kernel
1738 command line option "no387", which comes handy if your coprocessor
1739 is broken. Try "man bootparam" or see the documentation of your boot
1740 loader (lilo or loadlin) about how to pass options to the kernel at
1741 boot time.) This means that it is a good idea to say Y here if you
1742 intend to use this kernel on different machines.
1744 More information about the internals of the Linux math coprocessor
1745 emulation can be found in <file:arch/x86/math-emu/README>.
1747 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1748 kernel, it won't hurt.
1752 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1754 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1755 the Memory Type Range Registers (MTRRs) may be used to control
1756 processor access to memory ranges. This is most useful if you have
1757 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1758 allows bus write transfers to be combined into a larger transfer
1759 before bursting over the PCI/AGP bus. This can increase performance
1760 of image write operations 2.5 times or more. Saying Y here creates a
1761 /proc/mtrr file which may be used to manipulate your processor's
1762 MTRRs. Typically the X server should use this.
1764 This code has a reasonably generic interface so that similar
1765 control registers on other processors can be easily supported
1768 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1769 Registers (ARRs) which provide a similar functionality to MTRRs. For
1770 these, the ARRs are used to emulate the MTRRs.
1771 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1772 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1773 write-combining. All of these processors are supported by this code
1774 and it makes sense to say Y here if you have one of them.
1776 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1777 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1778 can lead to all sorts of problems, so it's good to say Y here.
1780 You can safely say Y even if your machine doesn't have MTRRs, you'll
1781 just add about 9 KB to your kernel.
1783 See <file:Documentation/x86/mtrr.txt> for more information.
1785 config MTRR_SANITIZER
1787 prompt "MTRR cleanup support"
1790 Convert MTRR layout from continuous to discrete, so X drivers can
1791 add writeback entries.
1793 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1794 The largest mtrr entry size for a continuous block can be set with
1799 config MTRR_SANITIZER_ENABLE_DEFAULT
1800 int "MTRR cleanup enable value (0-1)"
1803 depends on MTRR_SANITIZER
1805 Enable mtrr cleanup default value
1807 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1808 int "MTRR cleanup spare reg num (0-7)"
1811 depends on MTRR_SANITIZER
1813 mtrr cleanup spare entries default, it can be changed via
1814 mtrr_spare_reg_nr=N on the kernel command line.
1818 prompt "x86 PAT support" if EXPERT
1821 Use PAT attributes to setup page level cache control.
1823 PATs are the modern equivalents of MTRRs and are much more
1824 flexible than MTRRs.
1826 Say N here if you see bootup problems (boot crash, boot hang,
1827 spontaneous reboots) or a non-working video driver.
1831 config ARCH_USES_PG_UNCACHED
1837 prompt "x86 architectural random number generator" if EXPERT
1839 Enable the x86 architectural RDRAND instruction
1840 (Intel Bull Mountain technology) to generate random numbers.
1841 If supported, this is a high bandwidth, cryptographically
1842 secure hardware random number generator.
1846 prompt "Supervisor Mode Access Prevention" if EXPERT
1848 Supervisor Mode Access Prevention (SMAP) is a security
1849 feature in newer Intel processors. There is a small
1850 performance cost if this enabled and turned on; there is
1851 also a small increase in the kernel size if this is enabled.
1855 config X86_INTEL_UMIP
1857 depends on CPU_SUP_INTEL
1858 prompt "Intel User Mode Instruction Prevention" if EXPERT
1860 The User Mode Instruction Prevention (UMIP) is a security
1861 feature in newer Intel processors. If enabled, a general
1862 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1863 or STR instructions are executed in user mode. These instructions
1864 unnecessarily expose information about the hardware state.
1866 The vast majority of applications do not use these instructions.
1867 For the very few that do, software emulation is provided in
1868 specific cases in protected and virtual-8086 modes. Emulated
1871 config X86_INTEL_MPX
1872 prompt "Intel MPX (Memory Protection Extensions)"
1874 # Note: only available in 64-bit mode due to VMA flags shortage
1875 depends on CPU_SUP_INTEL && X86_64
1876 select ARCH_USES_HIGH_VMA_FLAGS
1878 MPX provides hardware features that can be used in
1879 conjunction with compiler-instrumented code to check
1880 memory references. It is designed to detect buffer
1881 overflow or underflow bugs.
1883 This option enables running applications which are
1884 instrumented or otherwise use MPX. It does not use MPX
1885 itself inside the kernel or to protect the kernel
1886 against bad memory references.
1888 Enabling this option will make the kernel larger:
1889 ~8k of kernel text and 36 bytes of data on a 64-bit
1890 defconfig. It adds a long to the 'mm_struct' which
1891 will increase the kernel memory overhead of each
1892 process and adds some branches to paths used during
1893 exec() and munmap().
1895 For details, see Documentation/x86/intel_mpx.txt
1899 config X86_INTEL_MEMORY_PROTECTION_KEYS
1900 prompt "Intel Memory Protection Keys"
1902 # Note: only available in 64-bit mode
1903 depends on CPU_SUP_INTEL && X86_64
1904 select ARCH_USES_HIGH_VMA_FLAGS
1905 select ARCH_HAS_PKEYS
1907 Memory Protection Keys provides a mechanism for enforcing
1908 page-based protections, but without requiring modification of the
1909 page tables when an application changes protection domains.
1911 For details, see Documentation/x86/protection-keys.txt
1916 bool "EFI runtime service support"
1919 select EFI_RUNTIME_WRAPPERS
1921 This enables the kernel to use EFI runtime services that are
1922 available (such as the EFI variable services).
1924 This option is only useful on systems that have EFI firmware.
1925 In addition, you should use the latest ELILO loader available
1926 at <http://elilo.sourceforge.net> in order to take advantage
1927 of EFI runtime services. However, even with this option, the
1928 resultant kernel should continue to boot on existing non-EFI
1932 bool "EFI stub support"
1933 depends on EFI && !X86_USE_3DNOW
1936 This kernel feature allows a bzImage to be loaded directly
1937 by EFI firmware without the use of a bootloader.
1939 See Documentation/efi-stub.txt for more information.
1942 bool "EFI mixed-mode support"
1943 depends on EFI_STUB && X86_64
1945 Enabling this feature allows a 64-bit kernel to be booted
1946 on a 32-bit firmware, provided that your CPU supports 64-bit
1949 Note that it is not possible to boot a mixed-mode enabled
1950 kernel via the EFI boot stub - a bootloader that supports
1951 the EFI handover protocol must be used.
1957 prompt "Enable seccomp to safely compute untrusted bytecode"
1959 This kernel feature is useful for number crunching applications
1960 that may need to compute untrusted bytecode during their
1961 execution. By using pipes or other transports made available to
1962 the process as file descriptors supporting the read/write
1963 syscalls, it's possible to isolate those applications in
1964 their own address space using seccomp. Once seccomp is
1965 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1966 and the task is only allowed to execute a few safe syscalls
1967 defined by each seccomp mode.
1969 If unsure, say Y. Only embedded should say N here.
1971 source "kernel/Kconfig.hz"
1974 bool "kexec system call"
1977 kexec is a system call that implements the ability to shutdown your
1978 current kernel, and to start another kernel. It is like a reboot
1979 but it is independent of the system firmware. And like a reboot
1980 you can start any kernel with it, not just Linux.
1982 The name comes from the similarity to the exec system call.
1984 It is an ongoing process to be certain the hardware in a machine
1985 is properly shutdown, so do not be surprised if this code does not
1986 initially work for you. As of this writing the exact hardware
1987 interface is strongly in flux, so no good recommendation can be
1991 bool "kexec file based system call"
1996 depends on CRYPTO_SHA256=y
1998 This is new version of kexec system call. This system call is
1999 file based and takes file descriptors as system call argument
2000 for kernel and initramfs as opposed to list of segments as
2001 accepted by previous system call.
2003 config ARCH_HAS_KEXEC_PURGATORY
2006 config KEXEC_VERIFY_SIG
2007 bool "Verify kernel signature during kexec_file_load() syscall"
2008 depends on KEXEC_FILE
2010 This option makes kernel signature verification mandatory for
2011 the kexec_file_load() syscall.
2013 In addition to that option, you need to enable signature
2014 verification for the corresponding kernel image type being
2015 loaded in order for this to work.
2017 config KEXEC_BZIMAGE_VERIFY_SIG
2018 bool "Enable bzImage signature verification support"
2019 depends on KEXEC_VERIFY_SIG
2020 depends on SIGNED_PE_FILE_VERIFICATION
2021 select SYSTEM_TRUSTED_KEYRING
2023 Enable bzImage signature verification support.
2026 bool "kernel crash dumps"
2027 depends on X86_64 || (X86_32 && HIGHMEM)
2029 Generate crash dump after being started by kexec.
2030 This should be normally only set in special crash dump kernels
2031 which are loaded in the main kernel with kexec-tools into
2032 a specially reserved region and then later executed after
2033 a crash by kdump/kexec. The crash dump kernel must be compiled
2034 to a memory address not used by the main kernel or BIOS using
2035 PHYSICAL_START, or it must be built as a relocatable image
2036 (CONFIG_RELOCATABLE=y).
2037 For more details see Documentation/kdump/kdump.txt
2041 depends on KEXEC && HIBERNATION
2043 Jump between original kernel and kexeced kernel and invoke
2044 code in physical address mode via KEXEC
2046 config PHYSICAL_START
2047 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2050 This gives the physical address where the kernel is loaded.
2052 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2053 bzImage will decompress itself to above physical address and
2054 run from there. Otherwise, bzImage will run from the address where
2055 it has been loaded by the boot loader and will ignore above physical
2058 In normal kdump cases one does not have to set/change this option
2059 as now bzImage can be compiled as a completely relocatable image
2060 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2061 address. This option is mainly useful for the folks who don't want
2062 to use a bzImage for capturing the crash dump and want to use a
2063 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2064 to be specifically compiled to run from a specific memory area
2065 (normally a reserved region) and this option comes handy.
2067 So if you are using bzImage for capturing the crash dump,
2068 leave the value here unchanged to 0x1000000 and set
2069 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2070 for capturing the crash dump change this value to start of
2071 the reserved region. In other words, it can be set based on
2072 the "X" value as specified in the "crashkernel=YM@XM"
2073 command line boot parameter passed to the panic-ed
2074 kernel. Please take a look at Documentation/kdump/kdump.txt
2075 for more details about crash dumps.
2077 Usage of bzImage for capturing the crash dump is recommended as
2078 one does not have to build two kernels. Same kernel can be used
2079 as production kernel and capture kernel. Above option should have
2080 gone away after relocatable bzImage support is introduced. But it
2081 is present because there are users out there who continue to use
2082 vmlinux for dump capture. This option should go away down the
2085 Don't change this unless you know what you are doing.
2088 bool "Build a relocatable kernel"
2091 This builds a kernel image that retains relocation information
2092 so it can be loaded someplace besides the default 1MB.
2093 The relocations tend to make the kernel binary about 10% larger,
2094 but are discarded at runtime.
2096 One use is for the kexec on panic case where the recovery kernel
2097 must live at a different physical address than the primary
2100 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2101 it has been loaded at and the compile time physical address
2102 (CONFIG_PHYSICAL_START) is used as the minimum location.
2104 config RANDOMIZE_BASE
2105 bool "Randomize the address of the kernel image (KASLR)"
2106 depends on RELOCATABLE
2109 In support of Kernel Address Space Layout Randomization (KASLR),
2110 this randomizes the physical address at which the kernel image
2111 is decompressed and the virtual address where the kernel
2112 image is mapped, as a security feature that deters exploit
2113 attempts relying on knowledge of the location of kernel
2116 On 64-bit, the kernel physical and virtual addresses are
2117 randomized separately. The physical address will be anywhere
2118 between 16MB and the top of physical memory (up to 64TB). The
2119 virtual address will be randomized from 16MB up to 1GB (9 bits
2120 of entropy). Note that this also reduces the memory space
2121 available to kernel modules from 1.5GB to 1GB.
2123 On 32-bit, the kernel physical and virtual addresses are
2124 randomized together. They will be randomized from 16MB up to
2125 512MB (8 bits of entropy).
2127 Entropy is generated using the RDRAND instruction if it is
2128 supported. If RDTSC is supported, its value is mixed into
2129 the entropy pool as well. If neither RDRAND nor RDTSC are
2130 supported, then entropy is read from the i8254 timer. The
2131 usable entropy is limited by the kernel being built using
2132 2GB addressing, and that PHYSICAL_ALIGN must be at a
2133 minimum of 2MB. As a result, only 10 bits of entropy are
2134 theoretically possible, but the implementations are further
2135 limited due to memory layouts.
2139 # Relocation on x86 needs some additional build support
2140 config X86_NEED_RELOCS
2142 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2144 config PHYSICAL_ALIGN
2145 hex "Alignment value to which kernel should be aligned"
2147 range 0x2000 0x1000000 if X86_32
2148 range 0x200000 0x1000000 if X86_64
2150 This value puts the alignment restrictions on physical address
2151 where kernel is loaded and run from. Kernel is compiled for an
2152 address which meets above alignment restriction.
2154 If bootloader loads the kernel at a non-aligned address and
2155 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2156 address aligned to above value and run from there.
2158 If bootloader loads the kernel at a non-aligned address and
2159 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2160 load address and decompress itself to the address it has been
2161 compiled for and run from there. The address for which kernel is
2162 compiled already meets above alignment restrictions. Hence the
2163 end result is that kernel runs from a physical address meeting
2164 above alignment restrictions.
2166 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2167 this value must be a multiple of 0x200000.
2169 Don't change this unless you know what you are doing.
2171 config DYNAMIC_MEMORY_LAYOUT
2174 This option makes base addresses of vmalloc and vmemmap as well as
2175 __PAGE_OFFSET movable during boot.
2177 config RANDOMIZE_MEMORY
2178 bool "Randomize the kernel memory sections"
2180 depends on RANDOMIZE_BASE
2181 select DYNAMIC_MEMORY_LAYOUT
2182 default RANDOMIZE_BASE
2184 Randomizes the base virtual address of kernel memory sections
2185 (physical memory mapping, vmalloc & vmemmap). This security feature
2186 makes exploits relying on predictable memory locations less reliable.
2188 The order of allocations remains unchanged. Entropy is generated in
2189 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2190 configuration have in average 30,000 different possible virtual
2191 addresses for each memory section.
2195 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2196 hex "Physical memory mapping padding" if EXPERT
2197 depends on RANDOMIZE_MEMORY
2198 default "0xa" if MEMORY_HOTPLUG
2200 range 0x1 0x40 if MEMORY_HOTPLUG
2203 Define the padding in terabytes added to the existing physical
2204 memory size during kernel memory randomization. It is useful
2205 for memory hotplug support but reduces the entropy available for
2206 address randomization.
2208 If unsure, leave at the default value.
2214 config BOOTPARAM_HOTPLUG_CPU0
2215 bool "Set default setting of cpu0_hotpluggable"
2216 depends on HOTPLUG_CPU
2218 Set whether default state of cpu0_hotpluggable is on or off.
2220 Say Y here to enable CPU0 hotplug by default. If this switch
2221 is turned on, there is no need to give cpu0_hotplug kernel
2222 parameter and the CPU0 hotplug feature is enabled by default.
2224 Please note: there are two known CPU0 dependencies if you want
2225 to enable the CPU0 hotplug feature either by this switch or by
2226 cpu0_hotplug kernel parameter.
2228 First, resume from hibernate or suspend always starts from CPU0.
2229 So hibernate and suspend are prevented if CPU0 is offline.
2231 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2232 offline if any interrupt can not migrate out of CPU0. There may
2233 be other CPU0 dependencies.
2235 Please make sure the dependencies are under your control before
2236 you enable this feature.
2238 Say N if you don't want to enable CPU0 hotplug feature by default.
2239 You still can enable the CPU0 hotplug feature at boot by kernel
2240 parameter cpu0_hotplug.
2242 config DEBUG_HOTPLUG_CPU0
2244 prompt "Debug CPU0 hotplug"
2245 depends on HOTPLUG_CPU
2247 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2248 soon as possible and boots up userspace with CPU0 offlined. User
2249 can online CPU0 back after boot time.
2251 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2252 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2253 compilation or giving cpu0_hotplug kernel parameter at boot.
2259 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2260 depends on COMPAT_32
2262 Certain buggy versions of glibc will crash if they are
2263 presented with a 32-bit vDSO that is not mapped at the address
2264 indicated in its segment table.
2266 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2267 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2268 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2269 the only released version with the bug, but OpenSUSE 9
2270 contains a buggy "glibc 2.3.2".
2272 The symptom of the bug is that everything crashes on startup, saying:
2273 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2275 Saying Y here changes the default value of the vdso32 boot
2276 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2277 This works around the glibc bug but hurts performance.
2279 If unsure, say N: if you are compiling your own kernel, you
2280 are unlikely to be using a buggy version of glibc.
2283 prompt "vsyscall table for legacy applications"
2285 default LEGACY_VSYSCALL_EMULATE
2287 Legacy user code that does not know how to find the vDSO expects
2288 to be able to issue three syscalls by calling fixed addresses in
2289 kernel space. Since this location is not randomized with ASLR,
2290 it can be used to assist security vulnerability exploitation.
2292 This setting can be changed at boot time via the kernel command
2293 line parameter vsyscall=[emulate|none].
2295 On a system with recent enough glibc (2.14 or newer) and no
2296 static binaries, you can say None without a performance penalty
2297 to improve security.
2299 If unsure, select "Emulate".
2301 config LEGACY_VSYSCALL_EMULATE
2304 The kernel traps and emulates calls into the fixed
2305 vsyscall address mapping. This makes the mapping
2306 non-executable, but it still contains known contents,
2307 which could be used in certain rare security vulnerability
2308 exploits. This configuration is recommended when userspace
2309 still uses the vsyscall area.
2311 config LEGACY_VSYSCALL_NONE
2314 There will be no vsyscall mapping at all. This will
2315 eliminate any risk of ASLR bypass due to the vsyscall
2316 fixed address mapping. Attempts to use the vsyscalls
2317 will be reported to dmesg, so that either old or
2318 malicious userspace programs can be identified.
2323 bool "Built-in kernel command line"
2325 Allow for specifying boot arguments to the kernel at
2326 build time. On some systems (e.g. embedded ones), it is
2327 necessary or convenient to provide some or all of the
2328 kernel boot arguments with the kernel itself (that is,
2329 to not rely on the boot loader to provide them.)
2331 To compile command line arguments into the kernel,
2332 set this option to 'Y', then fill in the
2333 boot arguments in CONFIG_CMDLINE.
2335 Systems with fully functional boot loaders (i.e. non-embedded)
2336 should leave this option set to 'N'.
2339 string "Built-in kernel command string"
2340 depends on CMDLINE_BOOL
2343 Enter arguments here that should be compiled into the kernel
2344 image and used at boot time. If the boot loader provides a
2345 command line at boot time, it is appended to this string to
2346 form the full kernel command line, when the system boots.
2348 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2349 change this behavior.
2351 In most cases, the command line (whether built-in or provided
2352 by the boot loader) should specify the device for the root
2355 config CMDLINE_OVERRIDE
2356 bool "Built-in command line overrides boot loader arguments"
2357 depends on CMDLINE_BOOL
2359 Set this option to 'Y' to have the kernel ignore the boot loader
2360 command line, and use ONLY the built-in command line.
2362 This is used to work around broken boot loaders. This should
2363 be set to 'N' under normal conditions.
2365 config MODIFY_LDT_SYSCALL
2366 bool "Enable the LDT (local descriptor table)" if EXPERT
2369 Linux can allow user programs to install a per-process x86
2370 Local Descriptor Table (LDT) using the modify_ldt(2) system
2371 call. This is required to run 16-bit or segmented code such as
2372 DOSEMU or some Wine programs. It is also used by some very old
2373 threading libraries.
2375 Enabling this feature adds a small amount of overhead to
2376 context switches and increases the low-level kernel attack
2377 surface. Disabling it removes the modify_ldt(2) system call.
2379 Saying 'N' here may make sense for embedded or server kernels.
2381 source "kernel/livepatch/Kconfig"
2385 config ARCH_HAS_ADD_PAGES
2387 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2389 config ARCH_ENABLE_MEMORY_HOTPLUG
2391 depends on X86_64 || (X86_32 && HIGHMEM)
2393 config ARCH_ENABLE_MEMORY_HOTREMOVE
2395 depends on MEMORY_HOTPLUG
2397 config USE_PERCPU_NUMA_NODE_ID
2401 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2403 depends on X86_64 || X86_PAE
2405 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2407 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2409 config ARCH_ENABLE_THP_MIGRATION
2411 depends on X86_64 && TRANSPARENT_HUGEPAGE
2413 menu "Power management and ACPI options"
2415 config ARCH_HIBERNATION_HEADER
2417 depends on HIBERNATION
2419 source "kernel/power/Kconfig"
2421 source "drivers/acpi/Kconfig"
2423 source "drivers/sfi/Kconfig"
2430 tristate "APM (Advanced Power Management) BIOS support"
2431 depends on X86_32 && PM_SLEEP
2433 APM is a BIOS specification for saving power using several different
2434 techniques. This is mostly useful for battery powered laptops with
2435 APM compliant BIOSes. If you say Y here, the system time will be
2436 reset after a RESUME operation, the /proc/apm device will provide
2437 battery status information, and user-space programs will receive
2438 notification of APM "events" (e.g. battery status change).
2440 If you select "Y" here, you can disable actual use of the APM
2441 BIOS by passing the "apm=off" option to the kernel at boot time.
2443 Note that the APM support is almost completely disabled for
2444 machines with more than one CPU.
2446 In order to use APM, you will need supporting software. For location
2447 and more information, read <file:Documentation/power/apm-acpi.txt>
2448 and the Battery Powered Linux mini-HOWTO, available from
2449 <http://www.tldp.org/docs.html#howto>.
2451 This driver does not spin down disk drives (see the hdparm(8)
2452 manpage ("man 8 hdparm") for that), and it doesn't turn off
2453 VESA-compliant "green" monitors.
2455 This driver does not support the TI 4000M TravelMate and the ACER
2456 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2457 desktop machines also don't have compliant BIOSes, and this driver
2458 may cause those machines to panic during the boot phase.
2460 Generally, if you don't have a battery in your machine, there isn't
2461 much point in using this driver and you should say N. If you get
2462 random kernel OOPSes or reboots that don't seem to be related to
2463 anything, try disabling/enabling this option (or disabling/enabling
2466 Some other things you should try when experiencing seemingly random,
2469 1) make sure that you have enough swap space and that it is
2471 2) pass the "no-hlt" option to the kernel
2472 3) switch on floating point emulation in the kernel and pass
2473 the "no387" option to the kernel
2474 4) pass the "floppy=nodma" option to the kernel
2475 5) pass the "mem=4M" option to the kernel (thereby disabling
2476 all but the first 4 MB of RAM)
2477 6) make sure that the CPU is not over clocked.
2478 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2479 8) disable the cache from your BIOS settings
2480 9) install a fan for the video card or exchange video RAM
2481 10) install a better fan for the CPU
2482 11) exchange RAM chips
2483 12) exchange the motherboard.
2485 To compile this driver as a module, choose M here: the
2486 module will be called apm.
2490 config APM_IGNORE_USER_SUSPEND
2491 bool "Ignore USER SUSPEND"
2493 This option will ignore USER SUSPEND requests. On machines with a
2494 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2495 series notebooks, it is necessary to say Y because of a BIOS bug.
2497 config APM_DO_ENABLE
2498 bool "Enable PM at boot time"
2500 Enable APM features at boot time. From page 36 of the APM BIOS
2501 specification: "When disabled, the APM BIOS does not automatically
2502 power manage devices, enter the Standby State, enter the Suspend
2503 State, or take power saving steps in response to CPU Idle calls."
2504 This driver will make CPU Idle calls when Linux is idle (unless this
2505 feature is turned off -- see "Do CPU IDLE calls", below). This
2506 should always save battery power, but more complicated APM features
2507 will be dependent on your BIOS implementation. You may need to turn
2508 this option off if your computer hangs at boot time when using APM
2509 support, or if it beeps continuously instead of suspending. Turn
2510 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2511 T400CDT. This is off by default since most machines do fine without
2516 bool "Make CPU Idle calls when idle"
2518 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2519 On some machines, this can activate improved power savings, such as
2520 a slowed CPU clock rate, when the machine is idle. These idle calls
2521 are made after the idle loop has run for some length of time (e.g.,
2522 333 mS). On some machines, this will cause a hang at boot time or
2523 whenever the CPU becomes idle. (On machines with more than one CPU,
2524 this option does nothing.)
2526 config APM_DISPLAY_BLANK
2527 bool "Enable console blanking using APM"
2529 Enable console blanking using the APM. Some laptops can use this to
2530 turn off the LCD backlight when the screen blanker of the Linux
2531 virtual console blanks the screen. Note that this is only used by
2532 the virtual console screen blanker, and won't turn off the backlight
2533 when using the X Window system. This also doesn't have anything to
2534 do with your VESA-compliant power-saving monitor. Further, this
2535 option doesn't work for all laptops -- it might not turn off your
2536 backlight at all, or it might print a lot of errors to the console,
2537 especially if you are using gpm.
2539 config APM_ALLOW_INTS
2540 bool "Allow interrupts during APM BIOS calls"
2542 Normally we disable external interrupts while we are making calls to
2543 the APM BIOS as a measure to lessen the effects of a badly behaving
2544 BIOS implementation. The BIOS should reenable interrupts if it
2545 needs to. Unfortunately, some BIOSes do not -- especially those in
2546 many of the newer IBM Thinkpads. If you experience hangs when you
2547 suspend, try setting this to Y. Otherwise, say N.
2551 source "drivers/cpufreq/Kconfig"
2553 source "drivers/cpuidle/Kconfig"
2555 source "drivers/idle/Kconfig"
2560 menu "Bus options (PCI etc.)"
2563 prompt "PCI access mode"
2564 depends on X86_32 && PCI
2567 On PCI systems, the BIOS can be used to detect the PCI devices and
2568 determine their configuration. However, some old PCI motherboards
2569 have BIOS bugs and may crash if this is done. Also, some embedded
2570 PCI-based systems don't have any BIOS at all. Linux can also try to
2571 detect the PCI hardware directly without using the BIOS.
2573 With this option, you can specify how Linux should detect the
2574 PCI devices. If you choose "BIOS", the BIOS will be used,
2575 if you choose "Direct", the BIOS won't be used, and if you
2576 choose "MMConfig", then PCI Express MMCONFIG will be used.
2577 If you choose "Any", the kernel will try MMCONFIG, then the
2578 direct access method and falls back to the BIOS if that doesn't
2579 work. If unsure, go with the default, which is "Any".
2584 config PCI_GOMMCONFIG
2601 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2603 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2606 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2609 bool "Support mmconfig PCI config space access" if X86_64
2611 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2612 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2616 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2620 depends on PCI && XEN
2623 config MMCONF_FAM10H
2625 depends on X86_64 && PCI_MMCONFIG && ACPI
2627 config PCI_CNB20LE_QUIRK
2628 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2631 Read the PCI windows out of the CNB20LE host bridge. This allows
2632 PCI hotplug to work on systems with the CNB20LE chipset which do
2635 There's no public spec for this chipset, and this functionality
2636 is known to be incomplete.
2638 You should say N unless you know you need this.
2641 bool "ISA bus support on modern systems" if EXPERT
2643 Expose ISA bus device drivers and options available for selection and
2644 configuration. Enable this option if your target machine has an ISA
2645 bus. ISA is an older system, displaced by PCI and newer bus
2646 architectures -- if your target machine is modern, it probably does
2647 not have an ISA bus.
2651 # x86_64 have no ISA slots, but can have ISA-style DMA.
2653 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2656 Enables ISA-style DMA support for devices requiring such controllers.
2664 Find out whether you have ISA slots on your motherboard. ISA is the
2665 name of a bus system, i.e. the way the CPU talks to the other stuff
2666 inside your box. Other bus systems are PCI, EISA, MicroChannel
2667 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2668 newer boards don't support it. If you have ISA, say Y, otherwise N.
2671 tristate "NatSemi SCx200 support"
2673 This provides basic support for National Semiconductor's
2674 (now AMD's) Geode processors. The driver probes for the
2675 PCI-IDs of several on-chip devices, so its a good dependency
2676 for other scx200_* drivers.
2678 If compiled as a module, the driver is named scx200.
2680 config SCx200HR_TIMER
2681 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2685 This driver provides a clocksource built upon the on-chip
2686 27MHz high-resolution timer. Its also a workaround for
2687 NSC Geode SC-1100's buggy TSC, which loses time when the
2688 processor goes idle (as is done by the scheduler). The
2689 other workaround is idle=poll boot option.
2692 bool "One Laptop Per Child support"
2699 Add support for detecting the unique features of the OLPC
2703 bool "OLPC XO-1 Power Management"
2704 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2706 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2709 bool "OLPC XO-1 Real Time Clock"
2710 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2712 Add support for the XO-1 real time clock, which can be used as a
2713 programmable wakeup source.
2716 bool "OLPC XO-1 SCI extras"
2717 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2721 Add support for SCI-based features of the OLPC XO-1 laptop:
2722 - EC-driven system wakeups
2726 - AC adapter status updates
2727 - Battery status updates
2729 config OLPC_XO15_SCI
2730 bool "OLPC XO-1.5 SCI extras"
2731 depends on OLPC && ACPI
2734 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2735 - EC-driven system wakeups
2736 - AC adapter status updates
2737 - Battery status updates
2740 bool "PCEngines ALIX System Support (LED setup)"
2743 This option enables system support for the PCEngines ALIX.
2744 At present this just sets up LEDs for GPIO control on
2745 ALIX2/3/6 boards. However, other system specific setup should
2748 Note: You must still enable the drivers for GPIO and LED support
2749 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2751 Note: You have to set alix.force=1 for boards with Award BIOS.
2754 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2757 This option enables system support for the Soekris Engineering net5501.
2760 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2764 This option enables system support for the Traverse Technologies GEOS.
2767 bool "Technologic Systems TS-5500 platform support"
2769 select CHECK_SIGNATURE
2773 This option enables system support for the Technologic Systems TS-5500.
2779 depends on CPU_SUP_AMD && PCI
2782 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2784 Firmwares often provide initial graphics framebuffers so the BIOS,
2785 bootloader or kernel can show basic video-output during boot for
2786 user-guidance and debugging. Historically, x86 used the VESA BIOS
2787 Extensions and EFI-framebuffers for this, which are mostly limited
2789 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2790 framebuffers so the new generic system-framebuffer drivers can be
2791 used on x86. If the framebuffer is not compatible with the generic
2792 modes, it is advertised as fallback platform framebuffer so legacy
2793 drivers like efifb, vesafb and uvesafb can pick it up.
2794 If this option is not selected, all system framebuffers are always
2795 marked as fallback platform framebuffers as usual.
2797 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2798 not be able to pick up generic system framebuffers if this option
2799 is selected. You are highly encouraged to enable simplefb as
2800 replacement if you select this option. simplefb can correctly deal
2801 with generic system framebuffers. But you should still keep vesafb
2802 and others enabled as fallback if a system framebuffer is
2803 incompatible with simplefb.
2810 menu "Binary Emulations"
2812 config IA32_EMULATION
2813 bool "IA32 Emulation"
2815 select ARCH_WANT_OLD_COMPAT_IPC
2817 select COMPAT_BINFMT_ELF
2818 select COMPAT_OLD_SIGACTION
2820 Include code to run legacy 32-bit programs under a
2821 64-bit kernel. You should likely turn this on, unless you're
2822 100% sure that you don't have any 32-bit programs left.
2825 tristate "IA32 a.out support"
2826 depends on IA32_EMULATION
2829 Support old a.out binaries in the 32bit emulation.
2832 bool "x32 ABI for 64-bit mode"
2835 Include code to run binaries for the x32 native 32-bit ABI
2836 for 64-bit processors. An x32 process gets access to the
2837 full 64-bit register file and wide data path while leaving
2838 pointers at 32 bits for smaller memory footprint.
2840 You will need a recent binutils (2.22 or later) with
2841 elf32_x86_64 support enabled to compile a kernel with this
2846 depends on IA32_EMULATION || X86_32
2848 select OLD_SIGSUSPEND3
2852 depends on IA32_EMULATION || X86_X32
2855 config COMPAT_FOR_U64_ALIGNMENT
2858 config SYSVIPC_COMPAT
2866 config HAVE_ATOMIC_IOMAP
2870 config X86_DEV_DMA_OPS
2873 config HAVE_GENERIC_GUP
2876 source "drivers/firmware/Kconfig"
2878 source "arch/x86/kvm/Kconfig"