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
18 select HAVE_GENERIC_DMA_COHERENT
19 select MODULES_USE_ELF_REL
25 # Options that are inherently 64-bit kernel only:
26 select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
27 select ARCH_SUPPORTS_INT128
28 select ARCH_USE_CMPXCHG_LOCKREF
29 select HAVE_ARCH_SOFT_DIRTY
30 select MODULES_USE_ELF_RELA
31 select NEED_DMA_MAP_STATE
33 select X86_DEV_DMA_OPS
34 select ARCH_HAS_SYSCALL_WRAPPER
39 # ( Note that options that are marked 'if X86_64' could in principle be
40 # ported to 32-bit as well. )
45 # Note: keep this list sorted alphabetically
47 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
48 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
50 select ARCH_CLOCKSOURCE_DATA
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
67 select ARCH_HAS_SET_MEMORY
68 select ARCH_HAS_SG_CHAIN
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
78 select ARCH_SUPPORTS_ATOMIC_RMW
79 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
80 select ARCH_USE_BUILTIN_BSWAP
81 select ARCH_USE_QUEUED_RWLOCKS
82 select ARCH_USE_QUEUED_SPINLOCKS
83 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
84 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
85 select ARCH_WANTS_THP_SWAP if X86_64
86 select BUILDTIME_EXTABLE_SORT
88 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
89 select CLOCKSOURCE_WATCHDOG
90 select DCACHE_WORD_ACCESS
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_KASAN if X86_64
122 select HAVE_ARCH_KGDB
123 select HAVE_ARCH_MMAP_RND_BITS if MMU
124 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
125 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
126 select HAVE_ARCH_SECCOMP_FILTER
127 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
128 select HAVE_ARCH_TRACEHOOK
129 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
130 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
131 select HAVE_ARCH_VMAP_STACK if X86_64
132 select HAVE_ARCH_WITHIN_STACK_FRAMES
133 select HAVE_CC_STACKPROTECTOR
134 select HAVE_CMPXCHG_DOUBLE
135 select HAVE_CMPXCHG_LOCAL
136 select HAVE_CONTEXT_TRACKING if X86_64
137 select HAVE_COPY_THREAD_TLS
138 select HAVE_C_RECORDMCOUNT
139 select HAVE_DEBUG_KMEMLEAK
140 select HAVE_DEBUG_STACKOVERFLOW
141 select HAVE_DMA_CONTIGUOUS
142 select HAVE_DYNAMIC_FTRACE
143 select HAVE_DYNAMIC_FTRACE_WITH_REGS
145 select HAVE_EFFICIENT_UNALIGNED_ACCESS
146 select HAVE_EXIT_THREAD
147 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
148 select HAVE_FTRACE_MCOUNT_RECORD
149 select HAVE_FUNCTION_GRAPH_TRACER
150 select HAVE_FUNCTION_TRACER
151 select HAVE_GCC_PLUGINS
152 select HAVE_HW_BREAKPOINT
154 select HAVE_IOREMAP_PROT
155 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
156 select HAVE_IRQ_TIME_ACCOUNTING
157 select HAVE_KERNEL_BZIP2
158 select HAVE_KERNEL_GZIP
159 select HAVE_KERNEL_LZ4
160 select HAVE_KERNEL_LZMA
161 select HAVE_KERNEL_LZO
162 select HAVE_KERNEL_XZ
164 select HAVE_KPROBES_ON_FTRACE
165 select HAVE_FUNCTION_ERROR_INJECTION
166 select HAVE_KRETPROBES
168 select HAVE_LIVEPATCH if X86_64
170 select HAVE_MEMBLOCK_NODE_MAP
171 select HAVE_MIXED_BREAKPOINTS_REGS
172 select HAVE_MOD_ARCH_SPECIFIC
175 select HAVE_OPTPROBES
176 select HAVE_PCSPKR_PLATFORM
177 select HAVE_PERF_EVENTS
178 select HAVE_PERF_EVENTS_NMI
179 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
180 select HAVE_PERF_REGS
181 select HAVE_PERF_USER_STACK_DUMP
182 select HAVE_RCU_TABLE_FREE
183 select HAVE_REGS_AND_STACK_ACCESS_API
184 select HAVE_RELIABLE_STACKTRACE if X86_64 && UNWINDER_FRAME_POINTER && STACK_VALIDATION
185 select HAVE_STACK_VALIDATION if X86_64
187 select HAVE_SYSCALL_TRACEPOINTS
188 select HAVE_UNSTABLE_SCHED_CLOCK
189 select HAVE_USER_RETURN_NOTIFIER
190 select IRQ_FORCED_THREADING
191 select NEED_SG_DMA_LENGTH
192 select PCI_LOCKLESS_CONFIG
195 select RTC_MC146818_LIB
198 select SYSCTL_EXCEPTION_TRACE
199 select THREAD_INFO_IN_TASK
200 select USER_STACKTRACE_SUPPORT
202 select X86_FEATURE_NAMES if PROC_FS
204 config INSTRUCTION_DECODER
206 depends on KPROBES || PERF_EVENTS || UPROBES
210 default "elf32-i386" if X86_32
211 default "elf64-x86-64" if X86_64
213 config ARCH_DEFCONFIG
215 default "arch/x86/configs/i386_defconfig" if X86_32
216 default "arch/x86/configs/x86_64_defconfig" if X86_64
218 config LOCKDEP_SUPPORT
221 config STACKTRACE_SUPPORT
227 config ARCH_MMAP_RND_BITS_MIN
231 config ARCH_MMAP_RND_BITS_MAX
235 config ARCH_MMAP_RND_COMPAT_BITS_MIN
238 config ARCH_MMAP_RND_COMPAT_BITS_MAX
244 config GENERIC_ISA_DMA
246 depends on ISA_DMA_API
251 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
253 config GENERIC_BUG_RELATIVE_POINTERS
256 config GENERIC_HWEIGHT
259 config ARCH_MAY_HAVE_PC_FDC
261 depends on ISA_DMA_API
263 config RWSEM_XCHGADD_ALGORITHM
266 config GENERIC_CALIBRATE_DELAY
269 config ARCH_HAS_CPU_RELAX
272 config ARCH_HAS_CACHE_LINE_SIZE
275 config ARCH_HAS_FILTER_PGPROT
278 config HAVE_SETUP_PER_CPU_AREA
281 config NEED_PER_CPU_EMBED_FIRST_CHUNK
284 config NEED_PER_CPU_PAGE_FIRST_CHUNK
287 config ARCH_HIBERNATION_POSSIBLE
290 config ARCH_SUSPEND_POSSIBLE
293 config ARCH_WANT_HUGE_PMD_SHARE
296 config ARCH_WANT_GENERAL_HUGETLB
305 config ARCH_SUPPORTS_OPTIMIZED_INLINING
308 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
311 config KASAN_SHADOW_OFFSET
314 default 0xdffffc0000000000
316 config HAVE_INTEL_TXT
318 depends on INTEL_IOMMU && ACPI
322 depends on X86_32 && SMP
326 depends on X86_64 && SMP
328 config X86_32_LAZY_GS
330 depends on X86_32 && CC_STACKPROTECTOR_NONE
332 config ARCH_SUPPORTS_UPROBES
335 config FIX_EARLYCON_MEM
338 config DYNAMIC_PHYSICAL_MASK
341 config PGTABLE_LEVELS
343 default 5 if X86_5LEVEL
348 source "init/Kconfig"
349 source "kernel/Kconfig.freezer"
351 menu "Processor type and features"
354 bool "DMA memory allocation support" if EXPERT
357 DMA memory allocation support allows devices with less than 32-bit
358 addressing to allocate within the first 16MB of address space.
359 Disable if no such devices will be used.
364 bool "Symmetric multi-processing support"
366 This enables support for systems with more than one CPU. If you have
367 a system with only one CPU, say N. If you have a system with more
370 If you say N here, the kernel will run on uni- and multiprocessor
371 machines, but will use only one CPU of a multiprocessor machine. If
372 you say Y here, the kernel will run on many, but not all,
373 uniprocessor machines. On a uniprocessor machine, the kernel
374 will run faster if you say N here.
376 Note that if you say Y here and choose architecture "586" or
377 "Pentium" under "Processor family", the kernel will not work on 486
378 architectures. Similarly, multiprocessor kernels for the "PPro"
379 architecture may not work on all Pentium based boards.
381 People using multiprocessor machines who say Y here should also say
382 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
383 Management" code will be disabled if you say Y here.
385 See also <file:Documentation/x86/i386/IO-APIC.txt>,
386 <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
387 <http://www.tldp.org/docs.html#howto>.
389 If you don't know what to do here, say N.
391 config X86_FEATURE_NAMES
392 bool "Processor feature human-readable names" if EMBEDDED
395 This option compiles in a table of x86 feature bits and corresponding
396 names. This is required to support /proc/cpuinfo and a few kernel
397 messages. You can disable this to save space, at the expense of
398 making those few kernel messages show numeric feature bits instead.
403 bool "Support x2apic"
404 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
406 This enables x2apic support on CPUs that have this feature.
408 This allows 32-bit apic IDs (so it can support very large systems),
409 and accesses the local apic via MSRs not via mmio.
411 If you don't know what to do here, say N.
414 bool "Enable MPS table" if ACPI || SFI
416 depends on X86_LOCAL_APIC
418 For old smp systems that do not have proper acpi support. Newer systems
419 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
423 depends on X86_GOLDFISH
426 bool "Avoid speculative indirect branches in kernel"
428 select STACK_VALIDATION if HAVE_STACK_VALIDATION
430 Compile kernel with the retpoline compiler options to guard against
431 kernel-to-user data leaks by avoiding speculative indirect
432 branches. Requires a compiler with -mindirect-branch=thunk-extern
433 support for full protection. The kernel may run slower.
435 Without compiler support, at least indirect branches in assembler
436 code are eliminated. Since this includes the syscall entry path,
437 it is not entirely pointless.
440 bool "Intel Resource Director Technology support"
442 depends on X86 && CPU_SUP_INTEL
445 Select to enable resource allocation and monitoring which are
446 sub-features of Intel Resource Director Technology(RDT). More
447 information about RDT can be found in the Intel x86
448 Architecture Software Developer Manual.
454 bool "Support for big SMP systems with more than 8 CPUs"
457 This option is needed for the systems that have more than 8 CPUs
459 config X86_EXTENDED_PLATFORM
460 bool "Support for extended (non-PC) x86 platforms"
463 If you disable this option then the kernel will only support
464 standard PC platforms. (which covers the vast majority of
467 If you enable this option then you'll be able to select support
468 for the following (non-PC) 32 bit x86 platforms:
469 Goldfish (Android emulator)
472 SGI 320/540 (Visual Workstation)
473 STA2X11-based (e.g. Northville)
474 Moorestown MID devices
476 If you have one of these systems, or if you want to build a
477 generic distribution kernel, say Y here - otherwise say N.
481 config X86_EXTENDED_PLATFORM
482 bool "Support for extended (non-PC) x86 platforms"
485 If you disable this option then the kernel will only support
486 standard PC platforms. (which covers the vast majority of
489 If you enable this option then you'll be able to select support
490 for the following (non-PC) 64 bit x86 platforms:
495 If you have one of these systems, or if you want to build a
496 generic distribution kernel, say Y here - otherwise say N.
498 # This is an alphabetically sorted list of 64 bit extended platforms
499 # Please maintain the alphabetic order if and when there are additions
501 bool "Numascale NumaChip"
503 depends on X86_EXTENDED_PLATFORM
506 depends on X86_X2APIC
507 depends on PCI_MMCONFIG
509 Adds support for Numascale NumaChip large-SMP systems. Needed to
510 enable more than ~168 cores.
511 If you don't have one of these, you should say N here.
515 select HYPERVISOR_GUEST
517 depends on X86_64 && PCI
518 depends on X86_EXTENDED_PLATFORM
521 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
522 supposed to run on these EM64T-based machines. Only choose this option
523 if you have one of these machines.
526 bool "SGI Ultraviolet"
528 depends on X86_EXTENDED_PLATFORM
531 depends on X86_X2APIC
534 This option is needed in order to support SGI Ultraviolet systems.
535 If you don't have one of these, you should say N here.
537 # Following is an alphabetically sorted list of 32 bit extended platforms
538 # Please maintain the alphabetic order if and when there are additions
541 bool "Goldfish (Virtual Platform)"
542 depends on X86_EXTENDED_PLATFORM
544 Enable support for the Goldfish virtual platform used primarily
545 for Android development. Unless you are building for the Android
546 Goldfish emulator say N here.
549 bool "CE4100 TV platform"
551 depends on PCI_GODIRECT
552 depends on X86_IO_APIC
554 depends on X86_EXTENDED_PLATFORM
555 select X86_REBOOTFIXUPS
557 select OF_EARLY_FLATTREE
559 Select for the Intel CE media processor (CE4100) SOC.
560 This option compiles in support for the CE4100 SOC for settop
561 boxes and media devices.
564 bool "Intel MID platform support"
565 depends on X86_EXTENDED_PLATFORM
566 depends on X86_PLATFORM_DEVICES
568 depends on X86_64 || (PCI_GOANY && X86_32)
569 depends on X86_IO_APIC
575 select MFD_INTEL_MSIC
577 Select to build a kernel capable of supporting Intel MID (Mobile
578 Internet Device) platform systems which do not have the PCI legacy
579 interfaces. If you are building for a PC class system say N here.
581 Intel MID platforms are based on an Intel processor and chipset which
582 consume less power than most of the x86 derivatives.
584 config X86_INTEL_QUARK
585 bool "Intel Quark platform support"
587 depends on X86_EXTENDED_PLATFORM
588 depends on X86_PLATFORM_DEVICES
592 depends on X86_IO_APIC
597 Select to include support for Quark X1000 SoC.
598 Say Y here if you have a Quark based system such as the Arduino
599 compatible Intel Galileo.
601 config X86_INTEL_LPSS
602 bool "Intel Low Power Subsystem Support"
603 depends on X86 && ACPI
608 Select to build support for Intel Low Power Subsystem such as
609 found on Intel Lynxpoint PCH. Selecting this option enables
610 things like clock tree (common clock framework) and pincontrol
611 which are needed by the LPSS peripheral drivers.
613 config X86_AMD_PLATFORM_DEVICE
614 bool "AMD ACPI2Platform devices support"
619 Select to interpret AMD specific ACPI device to platform device
620 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
621 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
622 implemented under PINCTRL subsystem.
625 tristate "Intel SoC IOSF Sideband support for SoC platforms"
628 This option enables sideband register access support for Intel SoC
629 platforms. On these platforms the IOSF sideband is used in lieu of
630 MSR's for some register accesses, mostly but not limited to thermal
631 and power. Drivers may query the availability of this device to
632 determine if they need the sideband in order to work on these
633 platforms. The sideband is available on the following SoC products.
634 This list is not meant to be exclusive.
639 You should say Y if you are running a kernel on one of these SoC's.
641 config IOSF_MBI_DEBUG
642 bool "Enable IOSF sideband access through debugfs"
643 depends on IOSF_MBI && DEBUG_FS
645 Select this option to expose the IOSF sideband access registers (MCR,
646 MDR, MCRX) through debugfs to write and read register information from
647 different units on the SoC. This is most useful for obtaining device
648 state information for debug and analysis. As this is a general access
649 mechanism, users of this option would have specific knowledge of the
650 device they want to access.
652 If you don't require the option or are in doubt, say N.
655 bool "RDC R-321x SoC"
657 depends on X86_EXTENDED_PLATFORM
659 select X86_REBOOTFIXUPS
661 This option is needed for RDC R-321x system-on-chip, also known
663 If you don't have one of these chips, you should say N here.
665 config X86_32_NON_STANDARD
666 bool "Support non-standard 32-bit SMP architectures"
667 depends on X86_32 && SMP
668 depends on X86_EXTENDED_PLATFORM
670 This option compiles in the bigsmp and STA2X11 default
671 subarchitectures. It is intended for a generic binary
672 kernel. If you select them all, kernel will probe it one by
673 one and will fallback to default.
675 # Alphabetically sorted list of Non standard 32 bit platforms
677 config X86_SUPPORTS_MEMORY_FAILURE
679 # MCE code calls memory_failure():
681 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
682 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
683 depends on X86_64 || !SPARSEMEM
684 select ARCH_SUPPORTS_MEMORY_FAILURE
687 bool "STA2X11 Companion Chip Support"
688 depends on X86_32_NON_STANDARD && PCI
689 select ARCH_HAS_PHYS_TO_DMA
690 select X86_DEV_DMA_OPS
697 This adds support for boards based on the STA2X11 IO-Hub,
698 a.k.a. "ConneXt". The chip is used in place of the standard
699 PC chipset, so all "standard" peripherals are missing. If this
700 option is selected the kernel will still be able to boot on
701 standard PC machines.
704 tristate "Eurobraille/Iris poweroff module"
707 The Iris machines from EuroBraille do not have APM or ACPI support
708 to shut themselves down properly. A special I/O sequence is
709 needed to do so, which is what this module does at
712 This is only for Iris machines from EuroBraille.
716 config SCHED_OMIT_FRAME_POINTER
718 prompt "Single-depth WCHAN output"
721 Calculate simpler /proc/<PID>/wchan values. If this option
722 is disabled then wchan values will recurse back to the
723 caller function. This provides more accurate wchan values,
724 at the expense of slightly more scheduling overhead.
726 If in doubt, say "Y".
728 menuconfig HYPERVISOR_GUEST
729 bool "Linux guest support"
731 Say Y here to enable options for running Linux under various hyper-
732 visors. This option enables basic hypervisor detection and platform
735 If you say N, all options in this submenu will be skipped and
736 disabled, and Linux guest support won't be built in.
741 bool "Enable paravirtualization code"
743 This changes the kernel so it can modify itself when it is run
744 under a hypervisor, potentially improving performance significantly
745 over full virtualization. However, when run without a hypervisor
746 the kernel is theoretically slower and slightly larger.
748 config PARAVIRT_DEBUG
749 bool "paravirt-ops debugging"
750 depends on PARAVIRT && DEBUG_KERNEL
752 Enable to debug paravirt_ops internals. Specifically, BUG if
753 a paravirt_op is missing when it is called.
755 config PARAVIRT_SPINLOCKS
756 bool "Paravirtualization layer for spinlocks"
757 depends on PARAVIRT && SMP
759 Paravirtualized spinlocks allow a pvops backend to replace the
760 spinlock implementation with something virtualization-friendly
761 (for example, block the virtual CPU rather than spinning).
763 It has a minimal impact on native kernels and gives a nice performance
764 benefit on paravirtualized KVM / Xen kernels.
766 If you are unsure how to answer this question, answer Y.
768 config QUEUED_LOCK_STAT
769 bool "Paravirt queued spinlock statistics"
770 depends on PARAVIRT_SPINLOCKS && DEBUG_FS
772 Enable the collection of statistical data on the slowpath
773 behavior of paravirtualized queued spinlocks and report
776 source "arch/x86/xen/Kconfig"
779 bool "KVM Guest support (including kvmclock)"
781 select PARAVIRT_CLOCK
784 This option enables various optimizations for running under the KVM
785 hypervisor. It includes a paravirtualized clock, so that instead
786 of relying on a PIT (or probably other) emulation by the
787 underlying device model, the host provides the guest with
788 timing infrastructure such as time of day, and system time
791 bool "Enable debug information for KVM Guests in debugfs"
792 depends on KVM_GUEST && DEBUG_FS
795 This option enables collection of various statistics for KVM guest.
796 Statistics are displayed in debugfs filesystem. Enabling this option
797 may incur significant overhead.
799 config PARAVIRT_TIME_ACCOUNTING
800 bool "Paravirtual steal time accounting"
804 Select this option to enable fine granularity task steal time
805 accounting. Time spent executing other tasks in parallel with
806 the current vCPU is discounted from the vCPU power. To account for
807 that, there can be a small performance impact.
809 If in doubt, say N here.
811 config PARAVIRT_CLOCK
814 config JAILHOUSE_GUEST
815 bool "Jailhouse non-root cell support"
816 depends on X86_64 && PCI
819 This option allows to run Linux as guest in a Jailhouse non-root
820 cell. You can leave this option disabled if you only want to start
821 Jailhouse and run Linux afterwards in the root cell.
823 endif #HYPERVISOR_GUEST
828 source "arch/x86/Kconfig.cpu"
832 prompt "HPET Timer Support" if X86_32
834 Use the IA-PC HPET (High Precision Event Timer) to manage
835 time in preference to the PIT and RTC, if a HPET is
837 HPET is the next generation timer replacing legacy 8254s.
838 The HPET provides a stable time base on SMP
839 systems, unlike the TSC, but it is more expensive to access,
840 as it is off-chip. The interface used is documented
841 in the HPET spec, revision 1.
843 You can safely choose Y here. However, HPET will only be
844 activated if the platform and the BIOS support this feature.
845 Otherwise the 8254 will be used for timing services.
847 Choose N to continue using the legacy 8254 timer.
849 config HPET_EMULATE_RTC
851 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
854 def_bool y if X86_INTEL_MID
855 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
857 depends on X86_INTEL_MID && SFI
859 APB timer is the replacement for 8254, HPET on X86 MID platforms.
860 The APBT provides a stable time base on SMP
861 systems, unlike the TSC, but it is more expensive to access,
862 as it is off-chip. APB timers are always running regardless of CPU
863 C states, they are used as per CPU clockevent device when possible.
865 # Mark as expert because too many people got it wrong.
866 # The code disables itself when not needed.
869 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
870 bool "Enable DMI scanning" if EXPERT
872 Enabled scanning of DMI to identify machine quirks. Say Y
873 here unless you have verified that your setup is not
874 affected by entries in the DMI blacklist. Required by PNP
878 bool "Old AMD GART IOMMU support"
881 depends on X86_64 && PCI && AMD_NB
883 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
884 GART based hardware IOMMUs.
886 The GART supports full DMA access for devices with 32-bit access
887 limitations, on systems with more than 3 GB. This is usually needed
888 for USB, sound, many IDE/SATA chipsets and some other devices.
890 Newer systems typically have a modern AMD IOMMU, supported via
891 the CONFIG_AMD_IOMMU=y config option.
893 In normal configurations this driver is only active when needed:
894 there's more than 3 GB of memory and the system contains a
895 32-bit limited device.
900 bool "IBM Calgary IOMMU support"
903 depends on X86_64 && PCI
905 Support for hardware IOMMUs in IBM's xSeries x366 and x460
906 systems. Needed to run systems with more than 3GB of memory
907 properly with 32-bit PCI devices that do not support DAC
908 (Double Address Cycle). Calgary also supports bus level
909 isolation, where all DMAs pass through the IOMMU. This
910 prevents them from going anywhere except their intended
911 destination. This catches hard-to-find kernel bugs and
912 mis-behaving drivers and devices that do not use the DMA-API
913 properly to set up their DMA buffers. The IOMMU can be
914 turned off at boot time with the iommu=off parameter.
915 Normally the kernel will make the right choice by itself.
918 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
920 prompt "Should Calgary be enabled by default?"
921 depends on CALGARY_IOMMU
923 Should Calgary be enabled by default? if you choose 'y', Calgary
924 will be used (if it exists). If you choose 'n', Calgary will not be
925 used even if it exists. If you choose 'n' and would like to use
926 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
930 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
931 depends on X86_64 && SMP && DEBUG_KERNEL
932 select CPUMASK_OFFSTACK
934 Enable maximum number of CPUS and NUMA Nodes for this architecture.
938 # The maximum number of CPUs supported:
940 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
941 # and which can be configured interactively in the
942 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
944 # The ranges are different on 32-bit and 64-bit kernels, depending on
945 # hardware capabilities and scalability features of the kernel.
947 # ( If MAXSMP is enabled we just use the highest possible value and disable
948 # interactive configuration. )
951 config NR_CPUS_RANGE_BEGIN
953 default NR_CPUS_RANGE_END if MAXSMP
957 config NR_CPUS_RANGE_END
960 default 64 if SMP && X86_BIGSMP
961 default 8 if SMP && !X86_BIGSMP
964 config NR_CPUS_RANGE_END
967 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK)
968 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
971 config NR_CPUS_DEFAULT
974 default 32 if X86_BIGSMP
978 config NR_CPUS_DEFAULT
981 default 8192 if MAXSMP
986 int "Maximum number of CPUs" if SMP && !MAXSMP
987 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
988 default NR_CPUS_DEFAULT
990 This allows you to specify the maximum number of CPUs which this
991 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
992 supported value is 8192, otherwise the maximum value is 512. The
993 minimum value which makes sense is 2.
995 This is purely to save memory: each supported CPU adds about 8KB
999 bool "SMT (Hyperthreading) scheduler support"
1002 SMT scheduler support improves the CPU scheduler's decision making
1003 when dealing with Intel Pentium 4 chips with HyperThreading at a
1004 cost of slightly increased overhead in some places. If unsure say
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.
1037 source "kernel/Kconfig.preempt"
1041 depends on !SMP && X86_LOCAL_APIC
1044 bool "Local APIC support on uniprocessors" if !PCI_MSI
1046 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1048 A local APIC (Advanced Programmable Interrupt Controller) is an
1049 integrated interrupt controller in the CPU. If you have a single-CPU
1050 system which has a processor with a local APIC, you can say Y here to
1051 enable and use it. If you say Y here even though your machine doesn't
1052 have a local APIC, then the kernel will still run with no slowdown at
1053 all. The local APIC supports CPU-generated self-interrupts (timer,
1054 performance counters), and the NMI watchdog which detects hard
1057 config X86_UP_IOAPIC
1058 bool "IO-APIC support on uniprocessors"
1059 depends on X86_UP_APIC
1061 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1062 SMP-capable replacement for PC-style interrupt controllers. Most
1063 SMP systems and many recent uniprocessor systems have one.
1065 If you have a single-CPU system with an IO-APIC, you can say Y here
1066 to use it. If you say Y here even though your machine doesn't have
1067 an IO-APIC, then the kernel will still run with no slowdown at all.
1069 config X86_LOCAL_APIC
1071 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1072 select IRQ_DOMAIN_HIERARCHY
1073 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1077 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1079 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1080 bool "Reroute for broken boot IRQs"
1081 depends on X86_IO_APIC
1083 This option enables a workaround that fixes a source of
1084 spurious interrupts. This is recommended when threaded
1085 interrupt handling is used on systems where the generation of
1086 superfluous "boot interrupts" cannot be disabled.
1088 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1089 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1090 kernel does during interrupt handling). On chipsets where this
1091 boot IRQ generation cannot be disabled, this workaround keeps
1092 the original IRQ line masked so that only the equivalent "boot
1093 IRQ" is delivered to the CPUs. The workaround also tells the
1094 kernel to set up the IRQ handler on the boot IRQ line. In this
1095 way only one interrupt is delivered to the kernel. Otherwise
1096 the spurious second interrupt may cause the kernel to bring
1097 down (vital) interrupt lines.
1099 Only affects "broken" chipsets. Interrupt sharing may be
1100 increased on these systems.
1103 bool "Machine Check / overheating reporting"
1104 select GENERIC_ALLOCATOR
1107 Machine Check support allows the processor to notify the
1108 kernel if it detects a problem (e.g. overheating, data corruption).
1109 The action the kernel takes depends on the severity of the problem,
1110 ranging from warning messages to halting the machine.
1112 config X86_MCELOG_LEGACY
1113 bool "Support for deprecated /dev/mcelog character device"
1116 Enable support for /dev/mcelog which is needed by the old mcelog
1117 userspace logging daemon. Consider switching to the new generation
1120 config X86_MCE_INTEL
1122 prompt "Intel MCE features"
1123 depends on X86_MCE && X86_LOCAL_APIC
1125 Additional support for intel specific MCE features such as
1126 the thermal monitor.
1130 prompt "AMD MCE features"
1131 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1133 Additional support for AMD specific MCE features such as
1134 the DRAM Error Threshold.
1136 config X86_ANCIENT_MCE
1137 bool "Support for old Pentium 5 / WinChip machine checks"
1138 depends on X86_32 && X86_MCE
1140 Include support for machine check handling on old Pentium 5 or WinChip
1141 systems. These typically need to be enabled explicitly on the command
1144 config X86_MCE_THRESHOLD
1145 depends on X86_MCE_AMD || X86_MCE_INTEL
1148 config X86_MCE_INJECT
1149 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1150 tristate "Machine check injector support"
1152 Provide support for injecting machine checks for testing purposes.
1153 If you don't know what a machine check is and you don't do kernel
1154 QA it is safe to say n.
1156 config X86_THERMAL_VECTOR
1158 depends on X86_MCE_INTEL
1160 source "arch/x86/events/Kconfig"
1162 config X86_LEGACY_VM86
1163 bool "Legacy VM86 support"
1167 This option allows user programs to put the CPU into V8086
1168 mode, which is an 80286-era approximation of 16-bit real mode.
1170 Some very old versions of X and/or vbetool require this option
1171 for user mode setting. Similarly, DOSEMU will use it if
1172 available to accelerate real mode DOS programs. However, any
1173 recent version of DOSEMU, X, or vbetool should be fully
1174 functional even without kernel VM86 support, as they will all
1175 fall back to software emulation. Nevertheless, if you are using
1176 a 16-bit DOS program where 16-bit performance matters, vm86
1177 mode might be faster than emulation and you might want to
1180 Note that any app that works on a 64-bit kernel is unlikely to
1181 need this option, as 64-bit kernels don't, and can't, support
1182 V8086 mode. This option is also unrelated to 16-bit protected
1183 mode and is not needed to run most 16-bit programs under Wine.
1185 Enabling this option increases the complexity of the kernel
1186 and slows down exception handling a tiny bit.
1188 If unsure, say N here.
1192 default X86_LEGACY_VM86
1195 bool "Enable support for 16-bit segments" if EXPERT
1197 depends on MODIFY_LDT_SYSCALL
1199 This option is required by programs like Wine to run 16-bit
1200 protected mode legacy code on x86 processors. Disabling
1201 this option saves about 300 bytes on i386, or around 6K text
1202 plus 16K runtime memory on x86-64,
1206 depends on X86_16BIT && X86_32
1210 depends on X86_16BIT && X86_64
1212 config X86_VSYSCALL_EMULATION
1213 bool "Enable vsyscall emulation" if EXPERT
1217 This enables emulation of the legacy vsyscall page. Disabling
1218 it is roughly equivalent to booting with vsyscall=none, except
1219 that it will also disable the helpful warning if a program
1220 tries to use a vsyscall. With this option set to N, offending
1221 programs will just segfault, citing addresses of the form
1224 This option is required by many programs built before 2013, and
1225 care should be used even with newer programs if set to N.
1227 Disabling this option saves about 7K of kernel size and
1228 possibly 4K of additional runtime pagetable memory.
1231 tristate "Toshiba Laptop support"
1234 This adds a driver to safely access the System Management Mode of
1235 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1236 not work on models with a Phoenix BIOS. The System Management Mode
1237 is used to set the BIOS and power saving options on Toshiba portables.
1239 For information on utilities to make use of this driver see the
1240 Toshiba Linux utilities web site at:
1241 <http://www.buzzard.org.uk/toshiba/>.
1243 Say Y if you intend to run this kernel on a Toshiba portable.
1247 tristate "Dell i8k legacy laptop support"
1249 select SENSORS_DELL_SMM
1251 This option enables legacy /proc/i8k userspace interface in hwmon
1252 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1253 temperature and allows controlling fan speeds of Dell laptops via
1254 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1255 it reports also power and hotkey status. For fan speed control is
1256 needed userspace package i8kutils.
1258 Say Y if you intend to run this kernel on old Dell laptops or want to
1259 use userspace package i8kutils.
1262 config X86_REBOOTFIXUPS
1263 bool "Enable X86 board specific fixups for reboot"
1266 This enables chipset and/or board specific fixups to be done
1267 in order to get reboot to work correctly. This is only needed on
1268 some combinations of hardware and BIOS. The symptom, for which
1269 this config is intended, is when reboot ends with a stalled/hung
1272 Currently, the only fixup is for the Geode machines using
1273 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1275 Say Y if you want to enable the fixup. Currently, it's safe to
1276 enable this option even if you don't need it.
1280 bool "CPU microcode loading support"
1282 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1285 If you say Y here, you will be able to update the microcode on
1286 Intel and AMD processors. The Intel support is for the IA32 family,
1287 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1288 AMD support is for families 0x10 and later. You will obviously need
1289 the actual microcode binary data itself which is not shipped with
1292 The preferred method to load microcode from a detached initrd is described
1293 in Documentation/x86/microcode.txt. For that you need to enable
1294 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1295 initrd for microcode blobs.
1297 In addition, you can build the microcode into the kernel. For that you
1298 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1301 config MICROCODE_INTEL
1302 bool "Intel microcode loading support"
1303 depends on MICROCODE
1307 This options enables microcode patch loading support for Intel
1310 For the current Intel microcode data package go to
1311 <https://downloadcenter.intel.com> and search for
1312 'Linux Processor Microcode Data File'.
1314 config MICROCODE_AMD
1315 bool "AMD microcode loading support"
1316 depends on MICROCODE
1319 If you select this option, microcode patch loading support for AMD
1320 processors will be enabled.
1322 config MICROCODE_OLD_INTERFACE
1324 depends on MICROCODE
1327 tristate "/dev/cpu/*/msr - Model-specific register support"
1329 This device gives privileged processes access to the x86
1330 Model-Specific Registers (MSRs). It is a character device with
1331 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1332 MSR accesses are directed to a specific CPU on multi-processor
1336 tristate "/dev/cpu/*/cpuid - CPU information support"
1338 This device gives processes access to the x86 CPUID instruction to
1339 be executed on a specific processor. It is a character device
1340 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1344 prompt "High Memory Support"
1351 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1352 However, the address space of 32-bit x86 processors is only 4
1353 Gigabytes large. That means that, if you have a large amount of
1354 physical memory, not all of it can be "permanently mapped" by the
1355 kernel. The physical memory that's not permanently mapped is called
1358 If you are compiling a kernel which will never run on a machine with
1359 more than 1 Gigabyte total physical RAM, answer "off" here (default
1360 choice and suitable for most users). This will result in a "3GB/1GB"
1361 split: 3GB are mapped so that each process sees a 3GB virtual memory
1362 space and the remaining part of the 4GB virtual memory space is used
1363 by the kernel to permanently map as much physical memory as
1366 If the machine has between 1 and 4 Gigabytes physical RAM, then
1369 If more than 4 Gigabytes is used then answer "64GB" here. This
1370 selection turns Intel PAE (Physical Address Extension) mode on.
1371 PAE implements 3-level paging on IA32 processors. PAE is fully
1372 supported by Linux, PAE mode is implemented on all recent Intel
1373 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1374 then the kernel will not boot on CPUs that don't support PAE!
1376 The actual amount of total physical memory will either be
1377 auto detected or can be forced by using a kernel command line option
1378 such as "mem=256M". (Try "man bootparam" or see the documentation of
1379 your boot loader (lilo or loadlin) about how to pass options to the
1380 kernel at boot time.)
1382 If unsure, say "off".
1387 Select this if you have a 32-bit processor and between 1 and 4
1388 gigabytes of physical RAM.
1392 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1395 Select this if you have a 32-bit processor and more than 4
1396 gigabytes of physical RAM.
1401 prompt "Memory split" if EXPERT
1405 Select the desired split between kernel and user memory.
1407 If the address range available to the kernel is less than the
1408 physical memory installed, the remaining memory will be available
1409 as "high memory". Accessing high memory is a little more costly
1410 than low memory, as it needs to be mapped into the kernel first.
1411 Note that increasing the kernel address space limits the range
1412 available to user programs, making the address space there
1413 tighter. Selecting anything other than the default 3G/1G split
1414 will also likely make your kernel incompatible with binary-only
1417 If you are not absolutely sure what you are doing, leave this
1421 bool "3G/1G user/kernel split"
1422 config VMSPLIT_3G_OPT
1424 bool "3G/1G user/kernel split (for full 1G low memory)"
1426 bool "2G/2G user/kernel split"
1427 config VMSPLIT_2G_OPT
1429 bool "2G/2G user/kernel split (for full 2G low memory)"
1431 bool "1G/3G user/kernel split"
1436 default 0xB0000000 if VMSPLIT_3G_OPT
1437 default 0x80000000 if VMSPLIT_2G
1438 default 0x78000000 if VMSPLIT_2G_OPT
1439 default 0x40000000 if VMSPLIT_1G
1445 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1448 bool "PAE (Physical Address Extension) Support"
1449 depends on X86_32 && !HIGHMEM4G
1450 select PHYS_ADDR_T_64BIT
1453 PAE is required for NX support, and furthermore enables
1454 larger swapspace support for non-overcommit purposes. It
1455 has the cost of more pagetable lookup overhead, and also
1456 consumes more pagetable space per process.
1459 bool "Enable 5-level page tables support"
1460 select DYNAMIC_MEMORY_LAYOUT
1461 select SPARSEMEM_VMEMMAP
1464 5-level paging enables access to larger address space:
1465 upto 128 PiB of virtual address space and 4 PiB of
1466 physical address space.
1468 It will be supported by future Intel CPUs.
1470 A kernel with the option enabled can be booted on machines that
1471 support 4- or 5-level paging.
1473 See Documentation/x86/x86_64/5level-paging.txt for more
1478 config X86_DIRECT_GBPAGES
1480 depends on X86_64 && !DEBUG_PAGEALLOC
1482 Certain kernel features effectively disable kernel
1483 linear 1 GB mappings (even if the CPU otherwise
1484 supports them), so don't confuse the user by printing
1485 that we have them enabled.
1487 config ARCH_HAS_MEM_ENCRYPT
1490 config AMD_MEM_ENCRYPT
1491 bool "AMD Secure Memory Encryption (SME) support"
1492 depends on X86_64 && CPU_SUP_AMD
1493 select DYNAMIC_PHYSICAL_MASK
1495 Say yes to enable support for the encryption of system memory.
1496 This requires an AMD processor that supports Secure Memory
1499 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1500 bool "Activate AMD Secure Memory Encryption (SME) by default"
1502 depends on AMD_MEM_ENCRYPT
1504 Say yes to have system memory encrypted by default if running on
1505 an AMD processor that supports Secure Memory Encryption (SME).
1507 If set to Y, then the encryption of system memory can be
1508 deactivated with the mem_encrypt=off command line option.
1510 If set to N, then the encryption of system memory can be
1511 activated with the mem_encrypt=on command line option.
1513 config ARCH_USE_MEMREMAP_PROT
1515 depends on AMD_MEM_ENCRYPT
1517 # Common NUMA Features
1519 bool "Numa Memory Allocation and Scheduler Support"
1521 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1522 default y if X86_BIGSMP
1524 Enable NUMA (Non Uniform Memory Access) support.
1526 The kernel will try to allocate memory used by a CPU on the
1527 local memory controller of the CPU and add some more
1528 NUMA awareness to the kernel.
1530 For 64-bit this is recommended if the system is Intel Core i7
1531 (or later), AMD Opteron, or EM64T NUMA.
1533 For 32-bit this is only needed if you boot a 32-bit
1534 kernel on a 64-bit NUMA platform.
1536 Otherwise, you should say N.
1540 prompt "Old style AMD Opteron NUMA detection"
1541 depends on X86_64 && NUMA && PCI
1543 Enable AMD NUMA node topology detection. You should say Y here if
1544 you have a multi processor AMD system. This uses an old method to
1545 read the NUMA configuration directly from the builtin Northbridge
1546 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1547 which also takes priority if both are compiled in.
1549 config X86_64_ACPI_NUMA
1551 prompt "ACPI NUMA detection"
1552 depends on X86_64 && NUMA && ACPI && PCI
1555 Enable ACPI SRAT based node topology detection.
1557 # Some NUMA nodes have memory ranges that span
1558 # other nodes. Even though a pfn is valid and
1559 # between a node's start and end pfns, it may not
1560 # reside on that node. See memmap_init_zone()
1562 config NODES_SPAN_OTHER_NODES
1564 depends on X86_64_ACPI_NUMA
1567 bool "NUMA emulation"
1570 Enable NUMA emulation. A flat machine will be split
1571 into virtual nodes when booted with "numa=fake=N", where N is the
1572 number of nodes. This is only useful for debugging.
1575 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1577 default "10" if MAXSMP
1578 default "6" if X86_64
1580 depends on NEED_MULTIPLE_NODES
1582 Specify the maximum number of NUMA Nodes available on the target
1583 system. Increases memory reserved to accommodate various tables.
1585 config ARCH_HAVE_MEMORY_PRESENT
1587 depends on X86_32 && DISCONTIGMEM
1589 config ARCH_FLATMEM_ENABLE
1591 depends on X86_32 && !NUMA
1593 config ARCH_DISCONTIGMEM_ENABLE
1595 depends on NUMA && X86_32
1597 config ARCH_DISCONTIGMEM_DEFAULT
1599 depends on NUMA && X86_32
1601 config ARCH_SPARSEMEM_ENABLE
1603 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1604 select SPARSEMEM_STATIC if X86_32
1605 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1607 config ARCH_SPARSEMEM_DEFAULT
1611 config ARCH_SELECT_MEMORY_MODEL
1613 depends on ARCH_SPARSEMEM_ENABLE
1615 config ARCH_MEMORY_PROBE
1616 bool "Enable sysfs memory/probe interface"
1617 depends on X86_64 && MEMORY_HOTPLUG
1619 This option enables a sysfs memory/probe interface for testing.
1620 See Documentation/memory-hotplug.txt for more information.
1621 If you are unsure how to answer this question, answer N.
1623 config ARCH_PROC_KCORE_TEXT
1625 depends on X86_64 && PROC_KCORE
1627 config ILLEGAL_POINTER_VALUE
1630 default 0xdead000000000000 if X86_64
1634 config X86_PMEM_LEGACY_DEVICE
1637 config X86_PMEM_LEGACY
1638 tristate "Support non-standard NVDIMMs and ADR protected memory"
1639 depends on PHYS_ADDR_T_64BIT
1641 select X86_PMEM_LEGACY_DEVICE
1644 Treat memory marked using the non-standard e820 type of 12 as used
1645 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1646 The kernel will offer these regions to the 'pmem' driver so
1647 they can be used for persistent storage.
1652 bool "Allocate 3rd-level pagetables from highmem"
1655 The VM uses one page table entry for each page of physical memory.
1656 For systems with a lot of RAM, this can be wasteful of precious
1657 low memory. Setting this option will put user-space page table
1658 entries in high memory.
1660 config X86_CHECK_BIOS_CORRUPTION
1661 bool "Check for low memory corruption"
1663 Periodically check for memory corruption in low memory, which
1664 is suspected to be caused by BIOS. Even when enabled in the
1665 configuration, it is disabled at runtime. Enable it by
1666 setting "memory_corruption_check=1" on the kernel command
1667 line. By default it scans the low 64k of memory every 60
1668 seconds; see the memory_corruption_check_size and
1669 memory_corruption_check_period parameters in
1670 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1672 When enabled with the default parameters, this option has
1673 almost no overhead, as it reserves a relatively small amount
1674 of memory and scans it infrequently. It both detects corruption
1675 and prevents it from affecting the running system.
1677 It is, however, intended as a diagnostic tool; if repeatable
1678 BIOS-originated corruption always affects the same memory,
1679 you can use memmap= to prevent the kernel from using that
1682 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1683 bool "Set the default setting of memory_corruption_check"
1684 depends on X86_CHECK_BIOS_CORRUPTION
1687 Set whether the default state of memory_corruption_check is
1690 config X86_RESERVE_LOW
1691 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1695 Specify the amount of low memory to reserve for the BIOS.
1697 The first page contains BIOS data structures that the kernel
1698 must not use, so that page must always be reserved.
1700 By default we reserve the first 64K of physical RAM, as a
1701 number of BIOSes are known to corrupt that memory range
1702 during events such as suspend/resume or monitor cable
1703 insertion, so it must not be used by the kernel.
1705 You can set this to 4 if you are absolutely sure that you
1706 trust the BIOS to get all its memory reservations and usages
1707 right. If you know your BIOS have problems beyond the
1708 default 64K area, you can set this to 640 to avoid using the
1709 entire low memory range.
1711 If you have doubts about the BIOS (e.g. suspend/resume does
1712 not work or there's kernel crashes after certain hardware
1713 hotplug events) then you might want to enable
1714 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1715 typical corruption patterns.
1717 Leave this to the default value of 64 if you are unsure.
1719 config MATH_EMULATION
1721 depends on MODIFY_LDT_SYSCALL
1722 prompt "Math emulation" if X86_32
1724 Linux can emulate a math coprocessor (used for floating point
1725 operations) if you don't have one. 486DX and Pentium processors have
1726 a math coprocessor built in, 486SX and 386 do not, unless you added
1727 a 487DX or 387, respectively. (The messages during boot time can
1728 give you some hints here ["man dmesg"].) Everyone needs either a
1729 coprocessor or this emulation.
1731 If you don't have a math coprocessor, you need to say Y here; if you
1732 say Y here even though you have a coprocessor, the coprocessor will
1733 be used nevertheless. (This behavior can be changed with the kernel
1734 command line option "no387", which comes handy if your coprocessor
1735 is broken. Try "man bootparam" or see the documentation of your boot
1736 loader (lilo or loadlin) about how to pass options to the kernel at
1737 boot time.) This means that it is a good idea to say Y here if you
1738 intend to use this kernel on different machines.
1740 More information about the internals of the Linux math coprocessor
1741 emulation can be found in <file:arch/x86/math-emu/README>.
1743 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1744 kernel, it won't hurt.
1748 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1750 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1751 the Memory Type Range Registers (MTRRs) may be used to control
1752 processor access to memory ranges. This is most useful if you have
1753 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1754 allows bus write transfers to be combined into a larger transfer
1755 before bursting over the PCI/AGP bus. This can increase performance
1756 of image write operations 2.5 times or more. Saying Y here creates a
1757 /proc/mtrr file which may be used to manipulate your processor's
1758 MTRRs. Typically the X server should use this.
1760 This code has a reasonably generic interface so that similar
1761 control registers on other processors can be easily supported
1764 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1765 Registers (ARRs) which provide a similar functionality to MTRRs. For
1766 these, the ARRs are used to emulate the MTRRs.
1767 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1768 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1769 write-combining. All of these processors are supported by this code
1770 and it makes sense to say Y here if you have one of them.
1772 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1773 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1774 can lead to all sorts of problems, so it's good to say Y here.
1776 You can safely say Y even if your machine doesn't have MTRRs, you'll
1777 just add about 9 KB to your kernel.
1779 See <file:Documentation/x86/mtrr.txt> for more information.
1781 config MTRR_SANITIZER
1783 prompt "MTRR cleanup support"
1786 Convert MTRR layout from continuous to discrete, so X drivers can
1787 add writeback entries.
1789 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1790 The largest mtrr entry size for a continuous block can be set with
1795 config MTRR_SANITIZER_ENABLE_DEFAULT
1796 int "MTRR cleanup enable value (0-1)"
1799 depends on MTRR_SANITIZER
1801 Enable mtrr cleanup default value
1803 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1804 int "MTRR cleanup spare reg num (0-7)"
1807 depends on MTRR_SANITIZER
1809 mtrr cleanup spare entries default, it can be changed via
1810 mtrr_spare_reg_nr=N on the kernel command line.
1814 prompt "x86 PAT support" if EXPERT
1817 Use PAT attributes to setup page level cache control.
1819 PATs are the modern equivalents of MTRRs and are much more
1820 flexible than MTRRs.
1822 Say N here if you see bootup problems (boot crash, boot hang,
1823 spontaneous reboots) or a non-working video driver.
1827 config ARCH_USES_PG_UNCACHED
1833 prompt "x86 architectural random number generator" if EXPERT
1835 Enable the x86 architectural RDRAND instruction
1836 (Intel Bull Mountain technology) to generate random numbers.
1837 If supported, this is a high bandwidth, cryptographically
1838 secure hardware random number generator.
1842 prompt "Supervisor Mode Access Prevention" if EXPERT
1844 Supervisor Mode Access Prevention (SMAP) is a security
1845 feature in newer Intel processors. There is a small
1846 performance cost if this enabled and turned on; there is
1847 also a small increase in the kernel size if this is enabled.
1851 config X86_INTEL_UMIP
1853 depends on CPU_SUP_INTEL
1854 prompt "Intel User Mode Instruction Prevention" if EXPERT
1856 The User Mode Instruction Prevention (UMIP) is a security
1857 feature in newer Intel processors. If enabled, a general
1858 protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1859 or STR instructions are executed in user mode. These instructions
1860 unnecessarily expose information about the hardware state.
1862 The vast majority of applications do not use these instructions.
1863 For the very few that do, software emulation is provided in
1864 specific cases in protected and virtual-8086 modes. Emulated
1867 config X86_INTEL_MPX
1868 prompt "Intel MPX (Memory Protection Extensions)"
1870 # Note: only available in 64-bit mode due to VMA flags shortage
1871 depends on CPU_SUP_INTEL && X86_64
1872 select ARCH_USES_HIGH_VMA_FLAGS
1874 MPX provides hardware features that can be used in
1875 conjunction with compiler-instrumented code to check
1876 memory references. It is designed to detect buffer
1877 overflow or underflow bugs.
1879 This option enables running applications which are
1880 instrumented or otherwise use MPX. It does not use MPX
1881 itself inside the kernel or to protect the kernel
1882 against bad memory references.
1884 Enabling this option will make the kernel larger:
1885 ~8k of kernel text and 36 bytes of data on a 64-bit
1886 defconfig. It adds a long to the 'mm_struct' which
1887 will increase the kernel memory overhead of each
1888 process and adds some branches to paths used during
1889 exec() and munmap().
1891 For details, see Documentation/x86/intel_mpx.txt
1895 config X86_INTEL_MEMORY_PROTECTION_KEYS
1896 prompt "Intel Memory Protection Keys"
1898 # Note: only available in 64-bit mode
1899 depends on CPU_SUP_INTEL && X86_64
1900 select ARCH_USES_HIGH_VMA_FLAGS
1901 select ARCH_HAS_PKEYS
1903 Memory Protection Keys provides a mechanism for enforcing
1904 page-based protections, but without requiring modification of the
1905 page tables when an application changes protection domains.
1907 For details, see Documentation/x86/protection-keys.txt
1912 bool "EFI runtime service support"
1915 select EFI_RUNTIME_WRAPPERS
1917 This enables the kernel to use EFI runtime services that are
1918 available (such as the EFI variable services).
1920 This option is only useful on systems that have EFI firmware.
1921 In addition, you should use the latest ELILO loader available
1922 at <http://elilo.sourceforge.net> in order to take advantage
1923 of EFI runtime services. However, even with this option, the
1924 resultant kernel should continue to boot on existing non-EFI
1928 bool "EFI stub support"
1929 depends on EFI && !X86_USE_3DNOW
1932 This kernel feature allows a bzImage to be loaded directly
1933 by EFI firmware without the use of a bootloader.
1935 See Documentation/efi-stub.txt for more information.
1938 bool "EFI mixed-mode support"
1939 depends on EFI_STUB && X86_64
1941 Enabling this feature allows a 64-bit kernel to be booted
1942 on a 32-bit firmware, provided that your CPU supports 64-bit
1945 Note that it is not possible to boot a mixed-mode enabled
1946 kernel via the EFI boot stub - a bootloader that supports
1947 the EFI handover protocol must be used.
1953 prompt "Enable seccomp to safely compute untrusted bytecode"
1955 This kernel feature is useful for number crunching applications
1956 that may need to compute untrusted bytecode during their
1957 execution. By using pipes or other transports made available to
1958 the process as file descriptors supporting the read/write
1959 syscalls, it's possible to isolate those applications in
1960 their own address space using seccomp. Once seccomp is
1961 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1962 and the task is only allowed to execute a few safe syscalls
1963 defined by each seccomp mode.
1965 If unsure, say Y. Only embedded should say N here.
1967 source kernel/Kconfig.hz
1970 bool "kexec system call"
1973 kexec is a system call that implements the ability to shutdown your
1974 current kernel, and to start another kernel. It is like a reboot
1975 but it is independent of the system firmware. And like a reboot
1976 you can start any kernel with it, not just Linux.
1978 The name comes from the similarity to the exec system call.
1980 It is an ongoing process to be certain the hardware in a machine
1981 is properly shutdown, so do not be surprised if this code does not
1982 initially work for you. As of this writing the exact hardware
1983 interface is strongly in flux, so no good recommendation can be
1987 bool "kexec file based system call"
1992 depends on CRYPTO_SHA256=y
1994 This is new version of kexec system call. This system call is
1995 file based and takes file descriptors as system call argument
1996 for kernel and initramfs as opposed to list of segments as
1997 accepted by previous system call.
1999 config ARCH_HAS_KEXEC_PURGATORY
2002 config KEXEC_VERIFY_SIG
2003 bool "Verify kernel signature during kexec_file_load() syscall"
2004 depends on KEXEC_FILE
2006 This option makes kernel signature verification mandatory for
2007 the kexec_file_load() syscall.
2009 In addition to that option, you need to enable signature
2010 verification for the corresponding kernel image type being
2011 loaded in order for this to work.
2013 config KEXEC_BZIMAGE_VERIFY_SIG
2014 bool "Enable bzImage signature verification support"
2015 depends on KEXEC_VERIFY_SIG
2016 depends on SIGNED_PE_FILE_VERIFICATION
2017 select SYSTEM_TRUSTED_KEYRING
2019 Enable bzImage signature verification support.
2022 bool "kernel crash dumps"
2023 depends on X86_64 || (X86_32 && HIGHMEM)
2025 Generate crash dump after being started by kexec.
2026 This should be normally only set in special crash dump kernels
2027 which are loaded in the main kernel with kexec-tools into
2028 a specially reserved region and then later executed after
2029 a crash by kdump/kexec. The crash dump kernel must be compiled
2030 to a memory address not used by the main kernel or BIOS using
2031 PHYSICAL_START, or it must be built as a relocatable image
2032 (CONFIG_RELOCATABLE=y).
2033 For more details see Documentation/kdump/kdump.txt
2037 depends on KEXEC && HIBERNATION
2039 Jump between original kernel and kexeced kernel and invoke
2040 code in physical address mode via KEXEC
2042 config PHYSICAL_START
2043 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2046 This gives the physical address where the kernel is loaded.
2048 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2049 bzImage will decompress itself to above physical address and
2050 run from there. Otherwise, bzImage will run from the address where
2051 it has been loaded by the boot loader and will ignore above physical
2054 In normal kdump cases one does not have to set/change this option
2055 as now bzImage can be compiled as a completely relocatable image
2056 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2057 address. This option is mainly useful for the folks who don't want
2058 to use a bzImage for capturing the crash dump and want to use a
2059 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2060 to be specifically compiled to run from a specific memory area
2061 (normally a reserved region) and this option comes handy.
2063 So if you are using bzImage for capturing the crash dump,
2064 leave the value here unchanged to 0x1000000 and set
2065 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2066 for capturing the crash dump change this value to start of
2067 the reserved region. In other words, it can be set based on
2068 the "X" value as specified in the "crashkernel=YM@XM"
2069 command line boot parameter passed to the panic-ed
2070 kernel. Please take a look at Documentation/kdump/kdump.txt
2071 for more details about crash dumps.
2073 Usage of bzImage for capturing the crash dump is recommended as
2074 one does not have to build two kernels. Same kernel can be used
2075 as production kernel and capture kernel. Above option should have
2076 gone away after relocatable bzImage support is introduced. But it
2077 is present because there are users out there who continue to use
2078 vmlinux for dump capture. This option should go away down the
2081 Don't change this unless you know what you are doing.
2084 bool "Build a relocatable kernel"
2087 This builds a kernel image that retains relocation information
2088 so it can be loaded someplace besides the default 1MB.
2089 The relocations tend to make the kernel binary about 10% larger,
2090 but are discarded at runtime.
2092 One use is for the kexec on panic case where the recovery kernel
2093 must live at a different physical address than the primary
2096 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2097 it has been loaded at and the compile time physical address
2098 (CONFIG_PHYSICAL_START) is used as the minimum location.
2100 config RANDOMIZE_BASE
2101 bool "Randomize the address of the kernel image (KASLR)"
2102 depends on RELOCATABLE
2105 In support of Kernel Address Space Layout Randomization (KASLR),
2106 this randomizes the physical address at which the kernel image
2107 is decompressed and the virtual address where the kernel
2108 image is mapped, as a security feature that deters exploit
2109 attempts relying on knowledge of the location of kernel
2112 On 64-bit, the kernel physical and virtual addresses are
2113 randomized separately. The physical address will be anywhere
2114 between 16MB and the top of physical memory (up to 64TB). The
2115 virtual address will be randomized from 16MB up to 1GB (9 bits
2116 of entropy). Note that this also reduces the memory space
2117 available to kernel modules from 1.5GB to 1GB.
2119 On 32-bit, the kernel physical and virtual addresses are
2120 randomized together. They will be randomized from 16MB up to
2121 512MB (8 bits of entropy).
2123 Entropy is generated using the RDRAND instruction if it is
2124 supported. If RDTSC is supported, its value is mixed into
2125 the entropy pool as well. If neither RDRAND nor RDTSC are
2126 supported, then entropy is read from the i8254 timer. The
2127 usable entropy is limited by the kernel being built using
2128 2GB addressing, and that PHYSICAL_ALIGN must be at a
2129 minimum of 2MB. As a result, only 10 bits of entropy are
2130 theoretically possible, but the implementations are further
2131 limited due to memory layouts.
2135 # Relocation on x86 needs some additional build support
2136 config X86_NEED_RELOCS
2138 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2140 config PHYSICAL_ALIGN
2141 hex "Alignment value to which kernel should be aligned"
2143 range 0x2000 0x1000000 if X86_32
2144 range 0x200000 0x1000000 if X86_64
2146 This value puts the alignment restrictions on physical address
2147 where kernel is loaded and run from. Kernel is compiled for an
2148 address which meets above alignment restriction.
2150 If bootloader loads the kernel at a non-aligned address and
2151 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2152 address aligned to above value and run from there.
2154 If bootloader loads the kernel at a non-aligned address and
2155 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2156 load address and decompress itself to the address it has been
2157 compiled for and run from there. The address for which kernel is
2158 compiled already meets above alignment restrictions. Hence the
2159 end result is that kernel runs from a physical address meeting
2160 above alignment restrictions.
2162 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2163 this value must be a multiple of 0x200000.
2165 Don't change this unless you know what you are doing.
2167 config DYNAMIC_MEMORY_LAYOUT
2170 This option makes base addresses of vmalloc and vmemmap as well as
2171 __PAGE_OFFSET movable during boot.
2173 config RANDOMIZE_MEMORY
2174 bool "Randomize the kernel memory sections"
2176 depends on RANDOMIZE_BASE
2177 select DYNAMIC_MEMORY_LAYOUT
2178 default RANDOMIZE_BASE
2180 Randomizes the base virtual address of kernel memory sections
2181 (physical memory mapping, vmalloc & vmemmap). This security feature
2182 makes exploits relying on predictable memory locations less reliable.
2184 The order of allocations remains unchanged. Entropy is generated in
2185 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2186 configuration have in average 30,000 different possible virtual
2187 addresses for each memory section.
2191 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2192 hex "Physical memory mapping padding" if EXPERT
2193 depends on RANDOMIZE_MEMORY
2194 default "0xa" if MEMORY_HOTPLUG
2196 range 0x1 0x40 if MEMORY_HOTPLUG
2199 Define the padding in terabytes added to the existing physical
2200 memory size during kernel memory randomization. It is useful
2201 for memory hotplug support but reduces the entropy available for
2202 address randomization.
2204 If unsure, leave at the default value.
2207 bool "Support for hot-pluggable CPUs"
2210 Say Y here to allow turning CPUs off and on. CPUs can be
2211 controlled through /sys/devices/system/cpu.
2212 ( Note: power management support will enable this option
2213 automatically on SMP systems. )
2214 Say N if you want to disable CPU hotplug.
2216 config BOOTPARAM_HOTPLUG_CPU0
2217 bool "Set default setting of cpu0_hotpluggable"
2219 depends on HOTPLUG_CPU
2221 Set whether default state of cpu0_hotpluggable is on or off.
2223 Say Y here to enable CPU0 hotplug by default. If this switch
2224 is turned on, there is no need to give cpu0_hotplug kernel
2225 parameter and the CPU0 hotplug feature is enabled by default.
2227 Please note: there are two known CPU0 dependencies if you want
2228 to enable the CPU0 hotplug feature either by this switch or by
2229 cpu0_hotplug kernel parameter.
2231 First, resume from hibernate or suspend always starts from CPU0.
2232 So hibernate and suspend are prevented if CPU0 is offline.
2234 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2235 offline if any interrupt can not migrate out of CPU0. There may
2236 be other CPU0 dependencies.
2238 Please make sure the dependencies are under your control before
2239 you enable this feature.
2241 Say N if you don't want to enable CPU0 hotplug feature by default.
2242 You still can enable the CPU0 hotplug feature at boot by kernel
2243 parameter cpu0_hotplug.
2245 config DEBUG_HOTPLUG_CPU0
2247 prompt "Debug CPU0 hotplug"
2248 depends on HOTPLUG_CPU
2250 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2251 soon as possible and boots up userspace with CPU0 offlined. User
2252 can online CPU0 back after boot time.
2254 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2255 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2256 compilation or giving cpu0_hotplug kernel parameter at boot.
2262 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2263 depends on COMPAT_32
2265 Certain buggy versions of glibc will crash if they are
2266 presented with a 32-bit vDSO that is not mapped at the address
2267 indicated in its segment table.
2269 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2270 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2271 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2272 the only released version with the bug, but OpenSUSE 9
2273 contains a buggy "glibc 2.3.2".
2275 The symptom of the bug is that everything crashes on startup, saying:
2276 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2278 Saying Y here changes the default value of the vdso32 boot
2279 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2280 This works around the glibc bug but hurts performance.
2282 If unsure, say N: if you are compiling your own kernel, you
2283 are unlikely to be using a buggy version of glibc.
2286 prompt "vsyscall table for legacy applications"
2288 default LEGACY_VSYSCALL_EMULATE
2290 Legacy user code that does not know how to find the vDSO expects
2291 to be able to issue three syscalls by calling fixed addresses in
2292 kernel space. Since this location is not randomized with ASLR,
2293 it can be used to assist security vulnerability exploitation.
2295 This setting can be changed at boot time via the kernel command
2296 line parameter vsyscall=[emulate|none].
2298 On a system with recent enough glibc (2.14 or newer) and no
2299 static binaries, you can say None without a performance penalty
2300 to improve security.
2302 If unsure, select "Emulate".
2304 config LEGACY_VSYSCALL_EMULATE
2307 The kernel traps and emulates calls into the fixed
2308 vsyscall address mapping. This makes the mapping
2309 non-executable, but it still contains known contents,
2310 which could be used in certain rare security vulnerability
2311 exploits. This configuration is recommended when userspace
2312 still uses the vsyscall area.
2314 config LEGACY_VSYSCALL_NONE
2317 There will be no vsyscall mapping at all. This will
2318 eliminate any risk of ASLR bypass due to the vsyscall
2319 fixed address mapping. Attempts to use the vsyscalls
2320 will be reported to dmesg, so that either old or
2321 malicious userspace programs can be identified.
2326 bool "Built-in kernel command line"
2328 Allow for specifying boot arguments to the kernel at
2329 build time. On some systems (e.g. embedded ones), it is
2330 necessary or convenient to provide some or all of the
2331 kernel boot arguments with the kernel itself (that is,
2332 to not rely on the boot loader to provide them.)
2334 To compile command line arguments into the kernel,
2335 set this option to 'Y', then fill in the
2336 boot arguments in CONFIG_CMDLINE.
2338 Systems with fully functional boot loaders (i.e. non-embedded)
2339 should leave this option set to 'N'.
2342 string "Built-in kernel command string"
2343 depends on CMDLINE_BOOL
2346 Enter arguments here that should be compiled into the kernel
2347 image and used at boot time. If the boot loader provides a
2348 command line at boot time, it is appended to this string to
2349 form the full kernel command line, when the system boots.
2351 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2352 change this behavior.
2354 In most cases, the command line (whether built-in or provided
2355 by the boot loader) should specify the device for the root
2358 config CMDLINE_OVERRIDE
2359 bool "Built-in command line overrides boot loader arguments"
2360 depends on CMDLINE_BOOL
2362 Set this option to 'Y' to have the kernel ignore the boot loader
2363 command line, and use ONLY the built-in command line.
2365 This is used to work around broken boot loaders. This should
2366 be set to 'N' under normal conditions.
2368 config MODIFY_LDT_SYSCALL
2369 bool "Enable the LDT (local descriptor table)" if EXPERT
2372 Linux can allow user programs to install a per-process x86
2373 Local Descriptor Table (LDT) using the modify_ldt(2) system
2374 call. This is required to run 16-bit or segmented code such as
2375 DOSEMU or some Wine programs. It is also used by some very old
2376 threading libraries.
2378 Enabling this feature adds a small amount of overhead to
2379 context switches and increases the low-level kernel attack
2380 surface. Disabling it removes the modify_ldt(2) system call.
2382 Saying 'N' here may make sense for embedded or server kernels.
2384 source "kernel/livepatch/Kconfig"
2388 config ARCH_HAS_ADD_PAGES
2390 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2392 config ARCH_ENABLE_MEMORY_HOTPLUG
2394 depends on X86_64 || (X86_32 && HIGHMEM)
2396 config ARCH_ENABLE_MEMORY_HOTREMOVE
2398 depends on MEMORY_HOTPLUG
2400 config USE_PERCPU_NUMA_NODE_ID
2404 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2406 depends on X86_64 || X86_PAE
2408 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2410 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2412 config ARCH_ENABLE_THP_MIGRATION
2414 depends on X86_64 && TRANSPARENT_HUGEPAGE
2416 menu "Power management and ACPI options"
2418 config ARCH_HIBERNATION_HEADER
2420 depends on X86_64 && HIBERNATION
2422 source "kernel/power/Kconfig"
2424 source "drivers/acpi/Kconfig"
2426 source "drivers/sfi/Kconfig"
2433 tristate "APM (Advanced Power Management) BIOS support"
2434 depends on X86_32 && PM_SLEEP
2436 APM is a BIOS specification for saving power using several different
2437 techniques. This is mostly useful for battery powered laptops with
2438 APM compliant BIOSes. If you say Y here, the system time will be
2439 reset after a RESUME operation, the /proc/apm device will provide
2440 battery status information, and user-space programs will receive
2441 notification of APM "events" (e.g. battery status change).
2443 If you select "Y" here, you can disable actual use of the APM
2444 BIOS by passing the "apm=off" option to the kernel at boot time.
2446 Note that the APM support is almost completely disabled for
2447 machines with more than one CPU.
2449 In order to use APM, you will need supporting software. For location
2450 and more information, read <file:Documentation/power/apm-acpi.txt>
2451 and the Battery Powered Linux mini-HOWTO, available from
2452 <http://www.tldp.org/docs.html#howto>.
2454 This driver does not spin down disk drives (see the hdparm(8)
2455 manpage ("man 8 hdparm") for that), and it doesn't turn off
2456 VESA-compliant "green" monitors.
2458 This driver does not support the TI 4000M TravelMate and the ACER
2459 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2460 desktop machines also don't have compliant BIOSes, and this driver
2461 may cause those machines to panic during the boot phase.
2463 Generally, if you don't have a battery in your machine, there isn't
2464 much point in using this driver and you should say N. If you get
2465 random kernel OOPSes or reboots that don't seem to be related to
2466 anything, try disabling/enabling this option (or disabling/enabling
2469 Some other things you should try when experiencing seemingly random,
2472 1) make sure that you have enough swap space and that it is
2474 2) pass the "no-hlt" option to the kernel
2475 3) switch on floating point emulation in the kernel and pass
2476 the "no387" option to the kernel
2477 4) pass the "floppy=nodma" option to the kernel
2478 5) pass the "mem=4M" option to the kernel (thereby disabling
2479 all but the first 4 MB of RAM)
2480 6) make sure that the CPU is not over clocked.
2481 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2482 8) disable the cache from your BIOS settings
2483 9) install a fan for the video card or exchange video RAM
2484 10) install a better fan for the CPU
2485 11) exchange RAM chips
2486 12) exchange the motherboard.
2488 To compile this driver as a module, choose M here: the
2489 module will be called apm.
2493 config APM_IGNORE_USER_SUSPEND
2494 bool "Ignore USER SUSPEND"
2496 This option will ignore USER SUSPEND requests. On machines with a
2497 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2498 series notebooks, it is necessary to say Y because of a BIOS bug.
2500 config APM_DO_ENABLE
2501 bool "Enable PM at boot time"
2503 Enable APM features at boot time. From page 36 of the APM BIOS
2504 specification: "When disabled, the APM BIOS does not automatically
2505 power manage devices, enter the Standby State, enter the Suspend
2506 State, or take power saving steps in response to CPU Idle calls."
2507 This driver will make CPU Idle calls when Linux is idle (unless this
2508 feature is turned off -- see "Do CPU IDLE calls", below). This
2509 should always save battery power, but more complicated APM features
2510 will be dependent on your BIOS implementation. You may need to turn
2511 this option off if your computer hangs at boot time when using APM
2512 support, or if it beeps continuously instead of suspending. Turn
2513 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2514 T400CDT. This is off by default since most machines do fine without
2519 bool "Make CPU Idle calls when idle"
2521 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2522 On some machines, this can activate improved power savings, such as
2523 a slowed CPU clock rate, when the machine is idle. These idle calls
2524 are made after the idle loop has run for some length of time (e.g.,
2525 333 mS). On some machines, this will cause a hang at boot time or
2526 whenever the CPU becomes idle. (On machines with more than one CPU,
2527 this option does nothing.)
2529 config APM_DISPLAY_BLANK
2530 bool "Enable console blanking using APM"
2532 Enable console blanking using the APM. Some laptops can use this to
2533 turn off the LCD backlight when the screen blanker of the Linux
2534 virtual console blanks the screen. Note that this is only used by
2535 the virtual console screen blanker, and won't turn off the backlight
2536 when using the X Window system. This also doesn't have anything to
2537 do with your VESA-compliant power-saving monitor. Further, this
2538 option doesn't work for all laptops -- it might not turn off your
2539 backlight at all, or it might print a lot of errors to the console,
2540 especially if you are using gpm.
2542 config APM_ALLOW_INTS
2543 bool "Allow interrupts during APM BIOS calls"
2545 Normally we disable external interrupts while we are making calls to
2546 the APM BIOS as a measure to lessen the effects of a badly behaving
2547 BIOS implementation. The BIOS should reenable interrupts if it
2548 needs to. Unfortunately, some BIOSes do not -- especially those in
2549 many of the newer IBM Thinkpads. If you experience hangs when you
2550 suspend, try setting this to Y. Otherwise, say N.
2554 source "drivers/cpufreq/Kconfig"
2556 source "drivers/cpuidle/Kconfig"
2558 source "drivers/idle/Kconfig"
2563 menu "Bus options (PCI etc.)"
2569 Find out whether you have a PCI motherboard. PCI is the name of a
2570 bus system, i.e. the way the CPU talks to the other stuff inside
2571 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2572 VESA. If you have PCI, say Y, otherwise N.
2575 prompt "PCI access mode"
2576 depends on X86_32 && PCI
2579 On PCI systems, the BIOS can be used to detect the PCI devices and
2580 determine their configuration. However, some old PCI motherboards
2581 have BIOS bugs and may crash if this is done. Also, some embedded
2582 PCI-based systems don't have any BIOS at all. Linux can also try to
2583 detect the PCI hardware directly without using the BIOS.
2585 With this option, you can specify how Linux should detect the
2586 PCI devices. If you choose "BIOS", the BIOS will be used,
2587 if you choose "Direct", the BIOS won't be used, and if you
2588 choose "MMConfig", then PCI Express MMCONFIG will be used.
2589 If you choose "Any", the kernel will try MMCONFIG, then the
2590 direct access method and falls back to the BIOS if that doesn't
2591 work. If unsure, go with the default, which is "Any".
2596 config PCI_GOMMCONFIG
2613 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2615 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2618 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2621 bool "Support mmconfig PCI config space access" if X86_64
2623 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2624 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2628 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2632 depends on PCI && XEN
2639 config MMCONF_FAM10H
2641 depends on X86_64 && PCI_MMCONFIG && ACPI
2643 config PCI_CNB20LE_QUIRK
2644 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2647 Read the PCI windows out of the CNB20LE host bridge. This allows
2648 PCI hotplug to work on systems with the CNB20LE chipset which do
2651 There's no public spec for this chipset, and this functionality
2652 is known to be incomplete.
2654 You should say N unless you know you need this.
2656 source "drivers/pci/Kconfig"
2659 bool "ISA bus support on modern systems" if EXPERT
2661 Expose ISA bus device drivers and options available for selection and
2662 configuration. Enable this option if your target machine has an ISA
2663 bus. ISA is an older system, displaced by PCI and newer bus
2664 architectures -- if your target machine is modern, it probably does
2665 not have an ISA bus.
2669 # x86_64 have no ISA slots, but can have ISA-style DMA.
2671 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2674 Enables ISA-style DMA support for devices requiring such controllers.
2682 Find out whether you have ISA slots on your motherboard. ISA is the
2683 name of a bus system, i.e. the way the CPU talks to the other stuff
2684 inside your box. Other bus systems are PCI, EISA, MicroChannel
2685 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2686 newer boards don't support it. If you have ISA, say Y, otherwise N.
2692 The Extended Industry Standard Architecture (EISA) bus was
2693 developed as an open alternative to the IBM MicroChannel bus.
2695 The EISA bus provided some of the features of the IBM MicroChannel
2696 bus while maintaining backward compatibility with cards made for
2697 the older ISA bus. The EISA bus saw limited use between 1988 and
2698 1995 when it was made obsolete by the PCI bus.
2700 Say Y here if you are building a kernel for an EISA-based machine.
2704 source "drivers/eisa/Kconfig"
2707 tristate "NatSemi SCx200 support"
2709 This provides basic support for National Semiconductor's
2710 (now AMD's) Geode processors. The driver probes for the
2711 PCI-IDs of several on-chip devices, so its a good dependency
2712 for other scx200_* drivers.
2714 If compiled as a module, the driver is named scx200.
2716 config SCx200HR_TIMER
2717 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2721 This driver provides a clocksource built upon the on-chip
2722 27MHz high-resolution timer. Its also a workaround for
2723 NSC Geode SC-1100's buggy TSC, which loses time when the
2724 processor goes idle (as is done by the scheduler). The
2725 other workaround is idle=poll boot option.
2728 bool "One Laptop Per Child support"
2735 Add support for detecting the unique features of the OLPC
2739 bool "OLPC XO-1 Power Management"
2740 depends on OLPC && MFD_CS5535 && PM_SLEEP
2743 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2746 bool "OLPC XO-1 Real Time Clock"
2747 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2749 Add support for the XO-1 real time clock, which can be used as a
2750 programmable wakeup source.
2753 bool "OLPC XO-1 SCI extras"
2754 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2758 Add support for SCI-based features of the OLPC XO-1 laptop:
2759 - EC-driven system wakeups
2763 - AC adapter status updates
2764 - Battery status updates
2766 config OLPC_XO15_SCI
2767 bool "OLPC XO-1.5 SCI extras"
2768 depends on OLPC && ACPI
2771 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2772 - EC-driven system wakeups
2773 - AC adapter status updates
2774 - Battery status updates
2777 bool "PCEngines ALIX System Support (LED setup)"
2780 This option enables system support for the PCEngines ALIX.
2781 At present this just sets up LEDs for GPIO control on
2782 ALIX2/3/6 boards. However, other system specific setup should
2785 Note: You must still enable the drivers for GPIO and LED support
2786 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2788 Note: You have to set alix.force=1 for boards with Award BIOS.
2791 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2794 This option enables system support for the Soekris Engineering net5501.
2797 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2801 This option enables system support for the Traverse Technologies GEOS.
2804 bool "Technologic Systems TS-5500 platform support"
2806 select CHECK_SIGNATURE
2810 This option enables system support for the Technologic Systems TS-5500.
2816 depends on CPU_SUP_AMD && PCI
2818 source "drivers/pcmcia/Kconfig"
2821 tristate "RapidIO support"
2825 If enabled this option will include drivers and the core
2826 infrastructure code to support RapidIO interconnect devices.
2828 source "drivers/rapidio/Kconfig"
2831 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2833 Firmwares often provide initial graphics framebuffers so the BIOS,
2834 bootloader or kernel can show basic video-output during boot for
2835 user-guidance and debugging. Historically, x86 used the VESA BIOS
2836 Extensions and EFI-framebuffers for this, which are mostly limited
2838 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2839 framebuffers so the new generic system-framebuffer drivers can be
2840 used on x86. If the framebuffer is not compatible with the generic
2841 modes, it is adverticed as fallback platform framebuffer so legacy
2842 drivers like efifb, vesafb and uvesafb can pick it up.
2843 If this option is not selected, all system framebuffers are always
2844 marked as fallback platform framebuffers as usual.
2846 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2847 not be able to pick up generic system framebuffers if this option
2848 is selected. You are highly encouraged to enable simplefb as
2849 replacement if you select this option. simplefb can correctly deal
2850 with generic system framebuffers. But you should still keep vesafb
2851 and others enabled as fallback if a system framebuffer is
2852 incompatible with simplefb.
2859 menu "Executable file formats / Emulations"
2861 source "fs/Kconfig.binfmt"
2863 config IA32_EMULATION
2864 bool "IA32 Emulation"
2866 select ARCH_WANT_OLD_COMPAT_IPC
2868 select COMPAT_BINFMT_ELF
2869 select COMPAT_OLD_SIGACTION
2871 Include code to run legacy 32-bit programs under a
2872 64-bit kernel. You should likely turn this on, unless you're
2873 100% sure that you don't have any 32-bit programs left.
2876 tristate "IA32 a.out support"
2877 depends on IA32_EMULATION
2879 Support old a.out binaries in the 32bit emulation.
2882 bool "x32 ABI for 64-bit mode"
2885 Include code to run binaries for the x32 native 32-bit ABI
2886 for 64-bit processors. An x32 process gets access to the
2887 full 64-bit register file and wide data path while leaving
2888 pointers at 32 bits for smaller memory footprint.
2890 You will need a recent binutils (2.22 or later) with
2891 elf32_x86_64 support enabled to compile a kernel with this
2896 depends on IA32_EMULATION || X86_32
2898 select OLD_SIGSUSPEND3
2902 depends on IA32_EMULATION || X86_X32
2905 config COMPAT_FOR_U64_ALIGNMENT
2908 config SYSVIPC_COMPAT
2916 config HAVE_ATOMIC_IOMAP
2920 config X86_DEV_DMA_OPS
2922 depends on X86_64 || STA2X11
2924 config X86_DMA_REMAP
2928 config HAVE_GENERIC_GUP
2931 source "net/Kconfig"
2933 source "drivers/Kconfig"
2935 source "drivers/firmware/Kconfig"
2939 source "arch/x86/Kconfig.debug"
2941 source "security/Kconfig"
2943 source "crypto/Kconfig"
2945 source "arch/x86/kvm/Kconfig"
2947 source "lib/Kconfig"