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
20 select GENERIC_VDSO_32
25 # Options that are inherently 64-bit kernel only:
26 select ARCH_HAS_GIGANTIC_PAGE
27 select ARCH_SUPPORTS_INT128 if CC_HAS_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 ARCH_HAS_SYSCALL_WRAPPER
35 config FORCE_DYNAMIC_FTRACE
38 depends on FUNCTION_TRACER
41 We keep the static function tracing (!DYNAMIC_FTRACE) around
42 in order to test the non static function tracing in the
43 generic code, as other architectures still use it. But we
44 only need to keep it around for x86_64. No need to keep it
45 for x86_32. For x86_32, force DYNAMIC_FTRACE.
49 # ( Note that options that are marked 'if X86_64' could in principle be
50 # ported to 32-bit as well. )
55 # Note: keep this list sorted alphabetically
57 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
58 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
59 select ARCH_32BIT_OFF_T if X86_32
60 select ARCH_CLOCKSOURCE_DATA
61 select ARCH_CLOCKSOURCE_INIT
62 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
63 select ARCH_HAS_DEBUG_VIRTUAL
64 select ARCH_HAS_DEVMEM_IS_ALLOWED
65 select ARCH_HAS_ELF_RANDOMIZE
66 select ARCH_HAS_FAST_MULTIPLIER
67 select ARCH_HAS_FILTER_PGPROT
68 select ARCH_HAS_FORTIFY_SOURCE
69 select ARCH_HAS_GCOV_PROFILE_ALL
70 select ARCH_HAS_KCOV if X86_64
71 select ARCH_HAS_MEM_ENCRYPT
72 select ARCH_HAS_MEMBARRIER_SYNC_CORE
73 select ARCH_HAS_PMEM_API if X86_64
74 select ARCH_HAS_PTE_DEVMAP if X86_64
75 select ARCH_HAS_PTE_SPECIAL
76 select ARCH_HAS_REFCOUNT
77 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
78 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
79 select ARCH_HAS_SET_MEMORY
80 select ARCH_HAS_SET_DIRECT_MAP
81 select ARCH_HAS_STRICT_KERNEL_RWX
82 select ARCH_HAS_STRICT_MODULE_RWX
83 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
84 select ARCH_HAS_UBSAN_SANITIZE_ALL
85 select ARCH_HAVE_NMI_SAFE_CMPXCHG
86 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
87 select ARCH_MIGHT_HAVE_PC_PARPORT
88 select ARCH_MIGHT_HAVE_PC_SERIO
90 select ARCH_SUPPORTS_ACPI
91 select ARCH_SUPPORTS_ATOMIC_RMW
92 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
93 select ARCH_USE_BUILTIN_BSWAP
94 select ARCH_USE_QUEUED_RWLOCKS
95 select ARCH_USE_QUEUED_SPINLOCKS
96 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
97 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
98 select ARCH_WANT_HUGE_PMD_SHARE
99 select ARCH_WANTS_THP_SWAP if X86_64
100 select BUILDTIME_EXTABLE_SORT
102 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
103 select CLOCKSOURCE_WATCHDOG
104 select DCACHE_WORD_ACCESS
105 select EDAC_ATOMIC_SCRUB
107 select GENERIC_CLOCKEVENTS
108 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
109 select GENERIC_CLOCKEVENTS_MIN_ADJUST
110 select GENERIC_CMOS_UPDATE
111 select GENERIC_CPU_AUTOPROBE
112 select GENERIC_CPU_VULNERABILITIES
113 select GENERIC_EARLY_IOREMAP
114 select GENERIC_FIND_FIRST_BIT
116 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
117 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
118 select GENERIC_IRQ_MIGRATION if SMP
119 select GENERIC_IRQ_PROBE
120 select GENERIC_IRQ_RESERVATION_MODE
121 select GENERIC_IRQ_SHOW
122 select GENERIC_PENDING_IRQ if SMP
123 select GENERIC_SMP_IDLE_THREAD
124 select GENERIC_STRNCPY_FROM_USER
125 select GENERIC_STRNLEN_USER
126 select GENERIC_TIME_VSYSCALL
127 select GENERIC_GETTIMEOFDAY
128 select GUP_GET_PTE_LOW_HIGH if X86_PAE
129 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
130 select HAVE_ACPI_APEI if ACPI
131 select HAVE_ACPI_APEI_NMI if ACPI
132 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
133 select HAVE_ARCH_AUDITSYSCALL
134 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
135 select HAVE_ARCH_JUMP_LABEL
136 select HAVE_ARCH_JUMP_LABEL_RELATIVE
137 select HAVE_ARCH_KASAN if X86_64
138 select HAVE_ARCH_KGDB
139 select HAVE_ARCH_MMAP_RND_BITS if MMU
140 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
141 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
142 select HAVE_ARCH_PREL32_RELOCATIONS
143 select HAVE_ARCH_SECCOMP_FILTER
144 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
145 select HAVE_ARCH_STACKLEAK
146 select HAVE_ARCH_TRACEHOOK
147 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
148 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
149 select HAVE_ARCH_VMAP_STACK if X86_64
150 select HAVE_ARCH_WITHIN_STACK_FRAMES
151 select HAVE_ASM_MODVERSIONS
152 select HAVE_CMPXCHG_DOUBLE
153 select HAVE_CMPXCHG_LOCAL
154 select HAVE_CONTEXT_TRACKING if X86_64
155 select HAVE_COPY_THREAD_TLS
156 select HAVE_C_RECORDMCOUNT
157 select HAVE_DEBUG_KMEMLEAK
158 select HAVE_DMA_CONTIGUOUS
159 select HAVE_DYNAMIC_FTRACE
160 select HAVE_DYNAMIC_FTRACE_WITH_REGS
162 select HAVE_EFFICIENT_UNALIGNED_ACCESS
164 select HAVE_EXIT_THREAD
166 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
167 select HAVE_FTRACE_MCOUNT_RECORD
168 select HAVE_FUNCTION_GRAPH_TRACER
169 select HAVE_FUNCTION_TRACER
170 select HAVE_GCC_PLUGINS
171 select HAVE_HW_BREAKPOINT
173 select HAVE_IOREMAP_PROT
174 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
175 select HAVE_IRQ_TIME_ACCOUNTING
176 select HAVE_KERNEL_BZIP2
177 select HAVE_KERNEL_GZIP
178 select HAVE_KERNEL_LZ4
179 select HAVE_KERNEL_LZMA
180 select HAVE_KERNEL_LZO
181 select HAVE_KERNEL_XZ
183 select HAVE_KPROBES_ON_FTRACE
184 select HAVE_FUNCTION_ERROR_INJECTION
185 select HAVE_KRETPROBES
187 select HAVE_LIVEPATCH if X86_64
188 select HAVE_MEMBLOCK_NODE_MAP
189 select HAVE_MIXED_BREAKPOINTS_REGS
190 select HAVE_MOD_ARCH_SPECIFIC
194 select HAVE_OPTPROBES
195 select HAVE_PCSPKR_PLATFORM
196 select HAVE_PERF_EVENTS
197 select HAVE_PERF_EVENTS_NMI
198 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
200 select HAVE_PERF_REGS
201 select HAVE_PERF_USER_STACK_DUMP
202 select HAVE_RCU_TABLE_FREE if PARAVIRT
203 select HAVE_REGS_AND_STACK_ACCESS_API
204 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
205 select HAVE_FUNCTION_ARG_ACCESS_API
206 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
207 select HAVE_STACK_VALIDATION if X86_64
209 select HAVE_SYSCALL_TRACEPOINTS
210 select HAVE_UNSTABLE_SCHED_CLOCK
211 select HAVE_USER_RETURN_NOTIFIER
212 select HAVE_GENERIC_VDSO
213 select HOTPLUG_SMT if SMP
214 select IRQ_FORCED_THREADING
215 select NEED_SG_DMA_LENGTH
216 select PCI_DOMAINS if PCI
217 select PCI_LOCKLESS_CONFIG if PCI
220 select RTC_MC146818_LIB
223 select SYSCTL_EXCEPTION_TRACE
224 select THREAD_INFO_IN_TASK
225 select USER_STACKTRACE_SUPPORT
227 select X86_FEATURE_NAMES if PROC_FS
228 select PROC_PID_ARCH_STATUS if PROC_FS
230 config INSTRUCTION_DECODER
232 depends on KPROBES || PERF_EVENTS || UPROBES
236 default "elf32-i386" if X86_32
237 default "elf64-x86-64" if X86_64
239 config ARCH_DEFCONFIG
241 default "arch/x86/configs/i386_defconfig" if X86_32
242 default "arch/x86/configs/x86_64_defconfig" if X86_64
244 config LOCKDEP_SUPPORT
247 config STACKTRACE_SUPPORT
253 config ARCH_MMAP_RND_BITS_MIN
257 config ARCH_MMAP_RND_BITS_MAX
261 config ARCH_MMAP_RND_COMPAT_BITS_MIN
264 config ARCH_MMAP_RND_COMPAT_BITS_MAX
270 config GENERIC_ISA_DMA
272 depends on ISA_DMA_API
277 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
279 config GENERIC_BUG_RELATIVE_POINTERS
282 config ARCH_MAY_HAVE_PC_FDC
284 depends on ISA_DMA_API
286 config GENERIC_CALIBRATE_DELAY
289 config ARCH_HAS_CPU_RELAX
292 config ARCH_HAS_CACHE_LINE_SIZE
295 config ARCH_HAS_FILTER_PGPROT
298 config HAVE_SETUP_PER_CPU_AREA
301 config NEED_PER_CPU_EMBED_FIRST_CHUNK
304 config NEED_PER_CPU_PAGE_FIRST_CHUNK
307 config ARCH_HIBERNATION_POSSIBLE
310 config ARCH_SUSPEND_POSSIBLE
313 config ARCH_WANT_GENERAL_HUGETLB
322 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
325 config KASAN_SHADOW_OFFSET
328 default 0xdffffc0000000000
330 config HAVE_INTEL_TXT
332 depends on INTEL_IOMMU && ACPI
336 depends on X86_32 && SMP
340 depends on X86_64 && SMP
342 config X86_32_LAZY_GS
344 depends on X86_32 && !STACKPROTECTOR
346 config ARCH_SUPPORTS_UPROBES
349 config FIX_EARLYCON_MEM
352 config DYNAMIC_PHYSICAL_MASK
355 config PGTABLE_LEVELS
357 default 5 if X86_5LEVEL
362 config CC_HAS_SANE_STACKPROTECTOR
364 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
365 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
367 We have to make sure stack protector is unconditionally disabled if
368 the compiler produces broken code.
370 menu "Processor type and features"
373 bool "DMA memory allocation support" if EXPERT
376 DMA memory allocation support allows devices with less than 32-bit
377 addressing to allocate within the first 16MB of address space.
378 Disable if no such devices will be used.
383 bool "Symmetric multi-processing support"
385 This enables support for systems with more than one CPU. If you have
386 a system with only one CPU, say N. If you have a system with more
389 If you say N here, the kernel will run on uni- and multiprocessor
390 machines, but will use only one CPU of a multiprocessor machine. If
391 you say Y here, the kernel will run on many, but not all,
392 uniprocessor machines. On a uniprocessor machine, the kernel
393 will run faster if you say N here.
395 Note that if you say Y here and choose architecture "586" or
396 "Pentium" under "Processor family", the kernel will not work on 486
397 architectures. Similarly, multiprocessor kernels for the "PPro"
398 architecture may not work on all Pentium based boards.
400 People using multiprocessor machines who say Y here should also say
401 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
402 Management" code will be disabled if you say Y here.
404 See also <file:Documentation/x86/i386/IO-APIC.rst>,
405 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
406 <http://www.tldp.org/docs.html#howto>.
408 If you don't know what to do here, say N.
410 config X86_FEATURE_NAMES
411 bool "Processor feature human-readable names" if EMBEDDED
414 This option compiles in a table of x86 feature bits and corresponding
415 names. This is required to support /proc/cpuinfo and a few kernel
416 messages. You can disable this to save space, at the expense of
417 making those few kernel messages show numeric feature bits instead.
422 bool "Support x2apic"
423 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
425 This enables x2apic support on CPUs that have this feature.
427 This allows 32-bit apic IDs (so it can support very large systems),
428 and accesses the local apic via MSRs not via mmio.
430 If you don't know what to do here, say N.
433 bool "Enable MPS table" if ACPI || SFI
435 depends on X86_LOCAL_APIC
437 For old smp systems that do not have proper acpi support. Newer systems
438 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
442 depends on X86_GOLDFISH
445 bool "Avoid speculative indirect branches in kernel"
447 select STACK_VALIDATION if HAVE_STACK_VALIDATION
449 Compile kernel with the retpoline compiler options to guard against
450 kernel-to-user data leaks by avoiding speculative indirect
451 branches. Requires a compiler with -mindirect-branch=thunk-extern
452 support for full protection. The kernel may run slower.
454 config X86_CPU_RESCTRL
455 bool "x86 CPU resource control support"
456 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
459 Enable x86 CPU resource control support.
461 Provide support for the allocation and monitoring of system resources
464 Intel calls this Intel Resource Director Technology
465 (Intel(R) RDT). More information about RDT can be found in the
466 Intel x86 Architecture Software Developer Manual.
468 AMD calls this AMD Platform Quality of Service (AMD QoS).
469 More information about AMD QoS can be found in the AMD64 Technology
470 Platform Quality of Service Extensions manual.
476 bool "Support for big SMP systems with more than 8 CPUs"
479 This option is needed for the systems that have more than 8 CPUs
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) 32 bit x86 platforms:
491 Goldfish (Android emulator)
494 SGI 320/540 (Visual Workstation)
495 STA2X11-based (e.g. Northville)
496 Moorestown MID devices
498 If you have one of these systems, or if you want to build a
499 generic distribution kernel, say Y here - otherwise say N.
503 config X86_EXTENDED_PLATFORM
504 bool "Support for extended (non-PC) x86 platforms"
507 If you disable this option then the kernel will only support
508 standard PC platforms. (which covers the vast majority of
511 If you enable this option then you'll be able to select support
512 for the following (non-PC) 64 bit x86 platforms:
517 If you have one of these systems, or if you want to build a
518 generic distribution kernel, say Y here - otherwise say N.
520 # This is an alphabetically sorted list of 64 bit extended platforms
521 # Please maintain the alphabetic order if and when there are additions
523 bool "Numascale NumaChip"
525 depends on X86_EXTENDED_PLATFORM
528 depends on X86_X2APIC
529 depends on PCI_MMCONFIG
531 Adds support for Numascale NumaChip large-SMP systems. Needed to
532 enable more than ~168 cores.
533 If you don't have one of these, you should say N here.
537 select HYPERVISOR_GUEST
539 depends on X86_64 && PCI
540 depends on X86_EXTENDED_PLATFORM
543 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
544 supposed to run on these EM64T-based machines. Only choose this option
545 if you have one of these machines.
548 bool "SGI Ultraviolet"
550 depends on X86_EXTENDED_PLATFORM
553 depends on X86_X2APIC
556 This option is needed in order to support SGI Ultraviolet systems.
557 If you don't have one of these, you should say N here.
559 # Following is an alphabetically sorted list of 32 bit extended platforms
560 # Please maintain the alphabetic order if and when there are additions
563 bool "Goldfish (Virtual Platform)"
564 depends on X86_EXTENDED_PLATFORM
566 Enable support for the Goldfish virtual platform used primarily
567 for Android development. Unless you are building for the Android
568 Goldfish emulator say N here.
571 bool "CE4100 TV platform"
573 depends on PCI_GODIRECT
574 depends on X86_IO_APIC
576 depends on X86_EXTENDED_PLATFORM
577 select X86_REBOOTFIXUPS
579 select OF_EARLY_FLATTREE
581 Select for the Intel CE media processor (CE4100) SOC.
582 This option compiles in support for the CE4100 SOC for settop
583 boxes and media devices.
586 bool "Intel MID platform support"
587 depends on X86_EXTENDED_PLATFORM
588 depends on X86_PLATFORM_DEVICES
590 depends on X86_64 || (PCI_GOANY && X86_32)
591 depends on X86_IO_APIC
597 select MFD_INTEL_MSIC
599 Select to build a kernel capable of supporting Intel MID (Mobile
600 Internet Device) platform systems which do not have the PCI legacy
601 interfaces. If you are building for a PC class system say N here.
603 Intel MID platforms are based on an Intel processor and chipset which
604 consume less power than most of the x86 derivatives.
606 config X86_INTEL_QUARK
607 bool "Intel Quark platform support"
609 depends on X86_EXTENDED_PLATFORM
610 depends on X86_PLATFORM_DEVICES
614 depends on X86_IO_APIC
619 Select to include support for Quark X1000 SoC.
620 Say Y here if you have a Quark based system such as the Arduino
621 compatible Intel Galileo.
623 config X86_INTEL_LPSS
624 bool "Intel Low Power Subsystem Support"
625 depends on X86 && ACPI && PCI
630 Select to build support for Intel Low Power Subsystem such as
631 found on Intel Lynxpoint PCH. Selecting this option enables
632 things like clock tree (common clock framework) and pincontrol
633 which are needed by the LPSS peripheral drivers.
635 config X86_AMD_PLATFORM_DEVICE
636 bool "AMD ACPI2Platform devices support"
641 Select to interpret AMD specific ACPI device to platform device
642 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
643 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
644 implemented under PINCTRL subsystem.
647 tristate "Intel SoC IOSF Sideband support for SoC platforms"
650 This option enables sideband register access support for Intel SoC
651 platforms. On these platforms the IOSF sideband is used in lieu of
652 MSR's for some register accesses, mostly but not limited to thermal
653 and power. Drivers may query the availability of this device to
654 determine if they need the sideband in order to work on these
655 platforms. The sideband is available on the following SoC products.
656 This list is not meant to be exclusive.
661 You should say Y if you are running a kernel on one of these SoC's.
663 config IOSF_MBI_DEBUG
664 bool "Enable IOSF sideband access through debugfs"
665 depends on IOSF_MBI && DEBUG_FS
667 Select this option to expose the IOSF sideband access registers (MCR,
668 MDR, MCRX) through debugfs to write and read register information from
669 different units on the SoC. This is most useful for obtaining device
670 state information for debug and analysis. As this is a general access
671 mechanism, users of this option would have specific knowledge of the
672 device they want to access.
674 If you don't require the option or are in doubt, say N.
677 bool "RDC R-321x SoC"
679 depends on X86_EXTENDED_PLATFORM
681 select X86_REBOOTFIXUPS
683 This option is needed for RDC R-321x system-on-chip, also known
685 If you don't have one of these chips, you should say N here.
687 config X86_32_NON_STANDARD
688 bool "Support non-standard 32-bit SMP architectures"
689 depends on X86_32 && SMP
690 depends on X86_EXTENDED_PLATFORM
692 This option compiles in the bigsmp and STA2X11 default
693 subarchitectures. It is intended for a generic binary
694 kernel. If you select them all, kernel will probe it one by
695 one and will fallback to default.
697 # Alphabetically sorted list of Non standard 32 bit platforms
699 config X86_SUPPORTS_MEMORY_FAILURE
701 # MCE code calls memory_failure():
703 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
704 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
705 depends on X86_64 || !SPARSEMEM
706 select ARCH_SUPPORTS_MEMORY_FAILURE
709 bool "STA2X11 Companion Chip Support"
710 depends on X86_32_NON_STANDARD && PCI
711 select ARCH_HAS_PHYS_TO_DMA
716 This adds support for boards based on the STA2X11 IO-Hub,
717 a.k.a. "ConneXt". The chip is used in place of the standard
718 PC chipset, so all "standard" peripherals are missing. If this
719 option is selected the kernel will still be able to boot on
720 standard PC machines.
723 tristate "Eurobraille/Iris poweroff module"
726 The Iris machines from EuroBraille do not have APM or ACPI support
727 to shut themselves down properly. A special I/O sequence is
728 needed to do so, which is what this module does at
731 This is only for Iris machines from EuroBraille.
735 config SCHED_OMIT_FRAME_POINTER
737 prompt "Single-depth WCHAN output"
740 Calculate simpler /proc/<PID>/wchan values. If this option
741 is disabled then wchan values will recurse back to the
742 caller function. This provides more accurate wchan values,
743 at the expense of slightly more scheduling overhead.
745 If in doubt, say "Y".
747 menuconfig HYPERVISOR_GUEST
748 bool "Linux guest support"
750 Say Y here to enable options for running Linux under various hyper-
751 visors. This option enables basic hypervisor detection and platform
754 If you say N, all options in this submenu will be skipped and
755 disabled, and Linux guest support won't be built in.
760 bool "Enable paravirtualization code"
762 This changes the kernel so it can modify itself when it is run
763 under a hypervisor, potentially improving performance significantly
764 over full virtualization. However, when run without a hypervisor
765 the kernel is theoretically slower and slightly larger.
770 config PARAVIRT_DEBUG
771 bool "paravirt-ops debugging"
772 depends on PARAVIRT && DEBUG_KERNEL
774 Enable to debug paravirt_ops internals. Specifically, BUG if
775 a paravirt_op is missing when it is called.
777 config PARAVIRT_SPINLOCKS
778 bool "Paravirtualization layer for spinlocks"
779 depends on PARAVIRT && SMP
781 Paravirtualized spinlocks allow a pvops backend to replace the
782 spinlock implementation with something virtualization-friendly
783 (for example, block the virtual CPU rather than spinning).
785 It has a minimal impact on native kernels and gives a nice performance
786 benefit on paravirtualized KVM / Xen kernels.
788 If you are unsure how to answer this question, answer Y.
790 config X86_HV_CALLBACK_VECTOR
793 source "arch/x86/xen/Kconfig"
796 bool "KVM Guest support (including kvmclock)"
798 select PARAVIRT_CLOCK
799 select ARCH_CPUIDLE_HALTPOLL
802 This option enables various optimizations for running under the KVM
803 hypervisor. It includes a paravirtualized clock, so that instead
804 of relying on a PIT (or probably other) emulation by the
805 underlying device model, the host provides the guest with
806 timing infrastructure such as time of day, and system time
808 config ARCH_CPUIDLE_HALTPOLL
810 prompt "Disable host haltpoll when loading haltpoll driver"
812 If virtualized under KVM, disable host haltpoll.
815 bool "Support for running PVH guests"
817 This option enables the PVH entry point for guest virtual machines
818 as specified in the x86/HVM direct boot ABI.
821 bool "Enable debug information for KVM Guests in debugfs"
822 depends on KVM_GUEST && DEBUG_FS
824 This option enables collection of various statistics for KVM guest.
825 Statistics are displayed in debugfs filesystem. Enabling this option
826 may incur significant overhead.
828 config PARAVIRT_TIME_ACCOUNTING
829 bool "Paravirtual steal time accounting"
832 Select this option to enable fine granularity task steal time
833 accounting. Time spent executing other tasks in parallel with
834 the current vCPU is discounted from the vCPU power. To account for
835 that, there can be a small performance impact.
837 If in doubt, say N here.
839 config PARAVIRT_CLOCK
842 config JAILHOUSE_GUEST
843 bool "Jailhouse non-root cell support"
844 depends on X86_64 && PCI
847 This option allows to run Linux as guest in a Jailhouse non-root
848 cell. You can leave this option disabled if you only want to start
849 Jailhouse and run Linux afterwards in the root cell.
852 bool "ACRN Guest support"
854 select X86_HV_CALLBACK_VECTOR
856 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
857 a flexible, lightweight reference open-source hypervisor, built with
858 real-time and safety-criticality in mind. It is built for embedded
859 IOT with small footprint and real-time features. More details can be
860 found in https://projectacrn.org/.
862 endif #HYPERVISOR_GUEST
864 source "arch/x86/Kconfig.cpu"
868 prompt "HPET Timer Support" if X86_32
870 Use the IA-PC HPET (High Precision Event Timer) to manage
871 time in preference to the PIT and RTC, if a HPET is
873 HPET is the next generation timer replacing legacy 8254s.
874 The HPET provides a stable time base on SMP
875 systems, unlike the TSC, but it is more expensive to access,
876 as it is off-chip. The interface used is documented
877 in the HPET spec, revision 1.
879 You can safely choose Y here. However, HPET will only be
880 activated if the platform and the BIOS support this feature.
881 Otherwise the 8254 will be used for timing services.
883 Choose N to continue using the legacy 8254 timer.
885 config HPET_EMULATE_RTC
887 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
890 def_bool y if X86_INTEL_MID
891 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
893 depends on X86_INTEL_MID && SFI
895 APB timer is the replacement for 8254, HPET on X86 MID platforms.
896 The APBT provides a stable time base on SMP
897 systems, unlike the TSC, but it is more expensive to access,
898 as it is off-chip. APB timers are always running regardless of CPU
899 C states, they are used as per CPU clockevent device when possible.
901 # Mark as expert because too many people got it wrong.
902 # The code disables itself when not needed.
905 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
906 bool "Enable DMI scanning" if EXPERT
908 Enabled scanning of DMI to identify machine quirks. Say Y
909 here unless you have verified that your setup is not
910 affected by entries in the DMI blacklist. Required by PNP
914 bool "Old AMD GART IOMMU support"
917 depends on X86_64 && PCI && AMD_NB
919 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
920 GART based hardware IOMMUs.
922 The GART supports full DMA access for devices with 32-bit access
923 limitations, on systems with more than 3 GB. This is usually needed
924 for USB, sound, many IDE/SATA chipsets and some other devices.
926 Newer systems typically have a modern AMD IOMMU, supported via
927 the CONFIG_AMD_IOMMU=y config option.
929 In normal configurations this driver is only active when needed:
930 there's more than 3 GB of memory and the system contains a
931 32-bit limited device.
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 && CPUMASK_OFFSTACK
974 default 512 if SMP && !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.rst. 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.rst
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.rst for more
1483 config X86_DIRECT_GBPAGES
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 AMD_MEM_ENCRYPT
1501 bool "AMD Secure Memory Encryption (SME) support"
1502 depends on X86_64 && CPU_SUP_AMD
1503 select DYNAMIC_PHYSICAL_MASK
1504 select ARCH_USE_MEMREMAP_PROT
1505 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1507 Say yes to enable support for the encryption of system memory.
1508 This requires an AMD processor that supports Secure Memory
1511 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1512 bool "Activate AMD Secure Memory Encryption (SME) by default"
1514 depends on AMD_MEM_ENCRYPT
1516 Say yes to have system memory encrypted by default if running on
1517 an AMD processor that supports Secure Memory Encryption (SME).
1519 If set to Y, then the encryption of system memory can be
1520 deactivated with the mem_encrypt=off command line option.
1522 If set to N, then the encryption of system memory can be
1523 activated with the mem_encrypt=on command line option.
1525 # Common NUMA Features
1527 bool "Numa Memory Allocation and Scheduler Support"
1529 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1530 default y if X86_BIGSMP
1532 Enable NUMA (Non Uniform Memory Access) support.
1534 The kernel will try to allocate memory used by a CPU on the
1535 local memory controller of the CPU and add some more
1536 NUMA awareness to the kernel.
1538 For 64-bit this is recommended if the system is Intel Core i7
1539 (or later), AMD Opteron, or EM64T NUMA.
1541 For 32-bit this is only needed if you boot a 32-bit
1542 kernel on a 64-bit NUMA platform.
1544 Otherwise, you should say N.
1548 prompt "Old style AMD Opteron NUMA detection"
1549 depends on X86_64 && NUMA && PCI
1551 Enable AMD NUMA node topology detection. You should say Y here if
1552 you have a multi processor AMD system. This uses an old method to
1553 read the NUMA configuration directly from the builtin Northbridge
1554 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1555 which also takes priority if both are compiled in.
1557 config X86_64_ACPI_NUMA
1559 prompt "ACPI NUMA detection"
1560 depends on X86_64 && NUMA && ACPI && PCI
1563 Enable ACPI SRAT based node topology detection.
1565 # Some NUMA nodes have memory ranges that span
1566 # other nodes. Even though a pfn is valid and
1567 # between a node's start and end pfns, it may not
1568 # reside on that node. See memmap_init_zone()
1570 config NODES_SPAN_OTHER_NODES
1572 depends on X86_64_ACPI_NUMA
1575 bool "NUMA emulation"
1578 Enable NUMA emulation. A flat machine will be split
1579 into virtual nodes when booted with "numa=fake=N", where N is the
1580 number of nodes. This is only useful for debugging.
1583 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1585 default "10" if MAXSMP
1586 default "6" if X86_64
1588 depends on NEED_MULTIPLE_NODES
1590 Specify the maximum number of NUMA Nodes available on the target
1591 system. Increases memory reserved to accommodate various tables.
1593 config ARCH_HAVE_MEMORY_PRESENT
1595 depends on X86_32 && DISCONTIGMEM
1597 config ARCH_FLATMEM_ENABLE
1599 depends on X86_32 && !NUMA
1601 config ARCH_DISCONTIGMEM_ENABLE
1603 depends on NUMA && X86_32
1606 config ARCH_SPARSEMEM_ENABLE
1608 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1609 select SPARSEMEM_STATIC if X86_32
1610 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1612 config ARCH_SPARSEMEM_DEFAULT
1613 def_bool X86_64 || (NUMA && X86_32)
1615 config ARCH_SELECT_MEMORY_MODEL
1617 depends on ARCH_SPARSEMEM_ENABLE
1619 config ARCH_MEMORY_PROBE
1620 bool "Enable sysfs memory/probe interface"
1621 depends on X86_64 && MEMORY_HOTPLUG
1623 This option enables a sysfs memory/probe interface for testing.
1624 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1625 If you are unsure how to answer this question, answer N.
1627 config ARCH_PROC_KCORE_TEXT
1629 depends on X86_64 && PROC_KCORE
1631 config ILLEGAL_POINTER_VALUE
1634 default 0xdead000000000000 if X86_64
1636 config X86_PMEM_LEGACY_DEVICE
1639 config X86_PMEM_LEGACY
1640 tristate "Support non-standard NVDIMMs and ADR protected memory"
1641 depends on PHYS_ADDR_T_64BIT
1643 select X86_PMEM_LEGACY_DEVICE
1646 Treat memory marked using the non-standard e820 type of 12 as used
1647 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1648 The kernel will offer these regions to the 'pmem' driver so
1649 they can be used for persistent storage.
1654 bool "Allocate 3rd-level pagetables from highmem"
1657 The VM uses one page table entry for each page of physical memory.
1658 For systems with a lot of RAM, this can be wasteful of precious
1659 low memory. Setting this option will put user-space page table
1660 entries in high memory.
1662 config X86_CHECK_BIOS_CORRUPTION
1663 bool "Check for low memory corruption"
1665 Periodically check for memory corruption in low memory, which
1666 is suspected to be caused by BIOS. Even when enabled in the
1667 configuration, it is disabled at runtime. Enable it by
1668 setting "memory_corruption_check=1" on the kernel command
1669 line. By default it scans the low 64k of memory every 60
1670 seconds; see the memory_corruption_check_size and
1671 memory_corruption_check_period parameters in
1672 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1674 When enabled with the default parameters, this option has
1675 almost no overhead, as it reserves a relatively small amount
1676 of memory and scans it infrequently. It both detects corruption
1677 and prevents it from affecting the running system.
1679 It is, however, intended as a diagnostic tool; if repeatable
1680 BIOS-originated corruption always affects the same memory,
1681 you can use memmap= to prevent the kernel from using that
1684 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1685 bool "Set the default setting of memory_corruption_check"
1686 depends on X86_CHECK_BIOS_CORRUPTION
1689 Set whether the default state of memory_corruption_check is
1692 config X86_RESERVE_LOW
1693 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1697 Specify the amount of low memory to reserve for the BIOS.
1699 The first page contains BIOS data structures that the kernel
1700 must not use, so that page must always be reserved.
1702 By default we reserve the first 64K of physical RAM, as a
1703 number of BIOSes are known to corrupt that memory range
1704 during events such as suspend/resume or monitor cable
1705 insertion, so it must not be used by the kernel.
1707 You can set this to 4 if you are absolutely sure that you
1708 trust the BIOS to get all its memory reservations and usages
1709 right. If you know your BIOS have problems beyond the
1710 default 64K area, you can set this to 640 to avoid using the
1711 entire low memory range.
1713 If you have doubts about the BIOS (e.g. suspend/resume does
1714 not work or there's kernel crashes after certain hardware
1715 hotplug events) then you might want to enable
1716 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1717 typical corruption patterns.
1719 Leave this to the default value of 64 if you are unsure.
1721 config MATH_EMULATION
1723 depends on MODIFY_LDT_SYSCALL
1724 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1726 Linux can emulate a math coprocessor (used for floating point
1727 operations) if you don't have one. 486DX and Pentium processors have
1728 a math coprocessor built in, 486SX and 386 do not, unless you added
1729 a 487DX or 387, respectively. (The messages during boot time can
1730 give you some hints here ["man dmesg"].) Everyone needs either a
1731 coprocessor or this emulation.
1733 If you don't have a math coprocessor, you need to say Y here; if you
1734 say Y here even though you have a coprocessor, the coprocessor will
1735 be used nevertheless. (This behavior can be changed with the kernel
1736 command line option "no387", which comes handy if your coprocessor
1737 is broken. Try "man bootparam" or see the documentation of your boot
1738 loader (lilo or loadlin) about how to pass options to the kernel at
1739 boot time.) This means that it is a good idea to say Y here if you
1740 intend to use this kernel on different machines.
1742 More information about the internals of the Linux math coprocessor
1743 emulation can be found in <file:arch/x86/math-emu/README>.
1745 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1746 kernel, it won't hurt.
1750 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1752 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1753 the Memory Type Range Registers (MTRRs) may be used to control
1754 processor access to memory ranges. This is most useful if you have
1755 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1756 allows bus write transfers to be combined into a larger transfer
1757 before bursting over the PCI/AGP bus. This can increase performance
1758 of image write operations 2.5 times or more. Saying Y here creates a
1759 /proc/mtrr file which may be used to manipulate your processor's
1760 MTRRs. Typically the X server should use this.
1762 This code has a reasonably generic interface so that similar
1763 control registers on other processors can be easily supported
1766 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1767 Registers (ARRs) which provide a similar functionality to MTRRs. For
1768 these, the ARRs are used to emulate the MTRRs.
1769 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1770 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1771 write-combining. All of these processors are supported by this code
1772 and it makes sense to say Y here if you have one of them.
1774 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1775 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1776 can lead to all sorts of problems, so it's good to say Y here.
1778 You can safely say Y even if your machine doesn't have MTRRs, you'll
1779 just add about 9 KB to your kernel.
1781 See <file:Documentation/x86/mtrr.rst> for more information.
1783 config MTRR_SANITIZER
1785 prompt "MTRR cleanup support"
1788 Convert MTRR layout from continuous to discrete, so X drivers can
1789 add writeback entries.
1791 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1792 The largest mtrr entry size for a continuous block can be set with
1797 config MTRR_SANITIZER_ENABLE_DEFAULT
1798 int "MTRR cleanup enable value (0-1)"
1801 depends on MTRR_SANITIZER
1803 Enable mtrr cleanup default value
1805 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1806 int "MTRR cleanup spare reg num (0-7)"
1809 depends on MTRR_SANITIZER
1811 mtrr cleanup spare entries default, it can be changed via
1812 mtrr_spare_reg_nr=N on the kernel command line.
1816 prompt "x86 PAT support" if EXPERT
1819 Use PAT attributes to setup page level cache control.
1821 PATs are the modern equivalents of MTRRs and are much more
1822 flexible than MTRRs.
1824 Say N here if you see bootup problems (boot crash, boot hang,
1825 spontaneous reboots) or a non-working video driver.
1829 config ARCH_USES_PG_UNCACHED
1835 prompt "x86 architectural random number generator" if EXPERT
1837 Enable the x86 architectural RDRAND instruction
1838 (Intel Bull Mountain technology) to generate random numbers.
1839 If supported, this is a high bandwidth, cryptographically
1840 secure hardware random number generator.
1844 prompt "Supervisor Mode Access Prevention" if EXPERT
1846 Supervisor Mode Access Prevention (SMAP) is a security
1847 feature in newer Intel processors. There is a small
1848 performance cost if this enabled and turned on; there is
1849 also a small increase in the kernel size if this is enabled.
1855 depends on CPU_SUP_INTEL || CPU_SUP_AMD
1856 prompt "User Mode Instruction Prevention" if EXPERT
1858 User Mode Instruction Prevention (UMIP) is a security feature in
1859 some x86 processors. If enabled, a general protection fault is
1860 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1861 executed in user mode. These instructions unnecessarily expose
1862 information about the hardware state.
1864 The vast majority of applications do not use these instructions.
1865 For the very few that do, software emulation is provided in
1866 specific cases in protected and virtual-8086 modes. Emulated
1869 config X86_INTEL_MPX
1870 prompt "Intel MPX (Memory Protection Extensions)"
1872 # Note: only available in 64-bit mode due to VMA flags shortage
1873 depends on CPU_SUP_INTEL && X86_64
1874 select ARCH_USES_HIGH_VMA_FLAGS
1876 MPX provides hardware features that can be used in
1877 conjunction with compiler-instrumented code to check
1878 memory references. It is designed to detect buffer
1879 overflow or underflow bugs.
1881 This option enables running applications which are
1882 instrumented or otherwise use MPX. It does not use MPX
1883 itself inside the kernel or to protect the kernel
1884 against bad memory references.
1886 Enabling this option will make the kernel larger:
1887 ~8k of kernel text and 36 bytes of data on a 64-bit
1888 defconfig. It adds a long to the 'mm_struct' which
1889 will increase the kernel memory overhead of each
1890 process and adds some branches to paths used during
1891 exec() and munmap().
1893 For details, see Documentation/x86/intel_mpx.rst
1897 config X86_INTEL_MEMORY_PROTECTION_KEYS
1898 prompt "Intel Memory Protection Keys"
1900 # Note: only available in 64-bit mode
1901 depends on CPU_SUP_INTEL && X86_64
1902 select ARCH_USES_HIGH_VMA_FLAGS
1903 select ARCH_HAS_PKEYS
1905 Memory Protection Keys provides a mechanism for enforcing
1906 page-based protections, but without requiring modification of the
1907 page tables when an application changes protection domains.
1909 For details, see Documentation/core-api/protection-keys.rst
1914 prompt "TSX enable mode"
1915 depends on CPU_SUP_INTEL
1916 default X86_INTEL_TSX_MODE_OFF
1918 Intel's TSX (Transactional Synchronization Extensions) feature
1919 allows to optimize locking protocols through lock elision which
1920 can lead to a noticeable performance boost.
1922 On the other hand it has been shown that TSX can be exploited
1923 to form side channel attacks (e.g. TAA) and chances are there
1924 will be more of those attacks discovered in the future.
1926 Therefore TSX is not enabled by default (aka tsx=off). An admin
1927 might override this decision by tsx=on the command line parameter.
1928 Even with TSX enabled, the kernel will attempt to enable the best
1929 possible TAA mitigation setting depending on the microcode available
1930 for the particular machine.
1932 This option allows to set the default tsx mode between tsx=on, =off
1933 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1936 Say off if not sure, auto if TSX is in use but it should be used on safe
1937 platforms or on if TSX is in use and the security aspect of tsx is not
1940 config X86_INTEL_TSX_MODE_OFF
1943 TSX is disabled if possible - equals to tsx=off command line parameter.
1945 config X86_INTEL_TSX_MODE_ON
1948 TSX is always enabled on TSX capable HW - equals the tsx=on command
1951 config X86_INTEL_TSX_MODE_AUTO
1954 TSX is enabled on TSX capable HW that is believed to be safe against
1955 side channel attacks- equals the tsx=auto command line parameter.
1959 bool "EFI runtime service support"
1962 select EFI_RUNTIME_WRAPPERS
1964 This enables the kernel to use EFI runtime services that are
1965 available (such as the EFI variable services).
1967 This option is only useful on systems that have EFI firmware.
1968 In addition, you should use the latest ELILO loader available
1969 at <http://elilo.sourceforge.net> in order to take advantage
1970 of EFI runtime services. However, even with this option, the
1971 resultant kernel should continue to boot on existing non-EFI
1975 bool "EFI stub support"
1976 depends on EFI && !X86_USE_3DNOW
1979 This kernel feature allows a bzImage to be loaded directly
1980 by EFI firmware without the use of a bootloader.
1982 See Documentation/admin-guide/efi-stub.rst for more information.
1985 bool "EFI mixed-mode support"
1986 depends on EFI_STUB && X86_64
1988 Enabling this feature allows a 64-bit kernel to be booted
1989 on a 32-bit firmware, provided that your CPU supports 64-bit
1992 Note that it is not possible to boot a mixed-mode enabled
1993 kernel via the EFI boot stub - a bootloader that supports
1994 the EFI handover protocol must be used.
2000 prompt "Enable seccomp to safely compute untrusted bytecode"
2002 This kernel feature is useful for number crunching applications
2003 that may need to compute untrusted bytecode during their
2004 execution. By using pipes or other transports made available to
2005 the process as file descriptors supporting the read/write
2006 syscalls, it's possible to isolate those applications in
2007 their own address space using seccomp. Once seccomp is
2008 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
2009 and the task is only allowed to execute a few safe syscalls
2010 defined by each seccomp mode.
2012 If unsure, say Y. Only embedded should say N here.
2014 source "kernel/Kconfig.hz"
2017 bool "kexec system call"
2020 kexec is a system call that implements the ability to shutdown your
2021 current kernel, and to start another kernel. It is like a reboot
2022 but it is independent of the system firmware. And like a reboot
2023 you can start any kernel with it, not just Linux.
2025 The name comes from the similarity to the exec system call.
2027 It is an ongoing process to be certain the hardware in a machine
2028 is properly shutdown, so do not be surprised if this code does not
2029 initially work for you. As of this writing the exact hardware
2030 interface is strongly in flux, so no good recommendation can be
2034 bool "kexec file based system call"
2039 depends on CRYPTO_SHA256=y
2041 This is new version of kexec system call. This system call is
2042 file based and takes file descriptors as system call argument
2043 for kernel and initramfs as opposed to list of segments as
2044 accepted by previous system call.
2046 config ARCH_HAS_KEXEC_PURGATORY
2050 bool "Verify kernel signature during kexec_file_load() syscall"
2051 depends on KEXEC_FILE
2054 This option makes the kexec_file_load() syscall check for a valid
2055 signature of the kernel image. The image can still be loaded without
2056 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2057 there's a signature that we can check, then it must be valid.
2059 In addition to this option, you need to enable signature
2060 verification for the corresponding kernel image type being
2061 loaded in order for this to work.
2063 config KEXEC_SIG_FORCE
2064 bool "Require a valid signature in kexec_file_load() syscall"
2065 depends on KEXEC_SIG
2067 This option makes kernel signature verification mandatory for
2068 the kexec_file_load() syscall.
2070 config KEXEC_BZIMAGE_VERIFY_SIG
2071 bool "Enable bzImage signature verification support"
2072 depends on KEXEC_SIG
2073 depends on SIGNED_PE_FILE_VERIFICATION
2074 select SYSTEM_TRUSTED_KEYRING
2076 Enable bzImage signature verification support.
2079 bool "kernel crash dumps"
2080 depends on X86_64 || (X86_32 && HIGHMEM)
2082 Generate crash dump after being started by kexec.
2083 This should be normally only set in special crash dump kernels
2084 which are loaded in the main kernel with kexec-tools into
2085 a specially reserved region and then later executed after
2086 a crash by kdump/kexec. The crash dump kernel must be compiled
2087 to a memory address not used by the main kernel or BIOS using
2088 PHYSICAL_START, or it must be built as a relocatable image
2089 (CONFIG_RELOCATABLE=y).
2090 For more details see Documentation/admin-guide/kdump/kdump.rst
2094 depends on KEXEC && HIBERNATION
2096 Jump between original kernel and kexeced kernel and invoke
2097 code in physical address mode via KEXEC
2099 config PHYSICAL_START
2100 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2103 This gives the physical address where the kernel is loaded.
2105 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2106 bzImage will decompress itself to above physical address and
2107 run from there. Otherwise, bzImage will run from the address where
2108 it has been loaded by the boot loader and will ignore above physical
2111 In normal kdump cases one does not have to set/change this option
2112 as now bzImage can be compiled as a completely relocatable image
2113 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2114 address. This option is mainly useful for the folks who don't want
2115 to use a bzImage for capturing the crash dump and want to use a
2116 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2117 to be specifically compiled to run from a specific memory area
2118 (normally a reserved region) and this option comes handy.
2120 So if you are using bzImage for capturing the crash dump,
2121 leave the value here unchanged to 0x1000000 and set
2122 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2123 for capturing the crash dump change this value to start of
2124 the reserved region. In other words, it can be set based on
2125 the "X" value as specified in the "crashkernel=YM@XM"
2126 command line boot parameter passed to the panic-ed
2127 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2128 for more details about crash dumps.
2130 Usage of bzImage for capturing the crash dump is recommended as
2131 one does not have to build two kernels. Same kernel can be used
2132 as production kernel and capture kernel. Above option should have
2133 gone away after relocatable bzImage support is introduced. But it
2134 is present because there are users out there who continue to use
2135 vmlinux for dump capture. This option should go away down the
2138 Don't change this unless you know what you are doing.
2141 bool "Build a relocatable kernel"
2144 This builds a kernel image that retains relocation information
2145 so it can be loaded someplace besides the default 1MB.
2146 The relocations tend to make the kernel binary about 10% larger,
2147 but are discarded at runtime.
2149 One use is for the kexec on panic case where the recovery kernel
2150 must live at a different physical address than the primary
2153 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2154 it has been loaded at and the compile time physical address
2155 (CONFIG_PHYSICAL_START) is used as the minimum location.
2157 config RANDOMIZE_BASE
2158 bool "Randomize the address of the kernel image (KASLR)"
2159 depends on RELOCATABLE
2162 In support of Kernel Address Space Layout Randomization (KASLR),
2163 this randomizes the physical address at which the kernel image
2164 is decompressed and the virtual address where the kernel
2165 image is mapped, as a security feature that deters exploit
2166 attempts relying on knowledge of the location of kernel
2169 On 64-bit, the kernel physical and virtual addresses are
2170 randomized separately. The physical address will be anywhere
2171 between 16MB and the top of physical memory (up to 64TB). The
2172 virtual address will be randomized from 16MB up to 1GB (9 bits
2173 of entropy). Note that this also reduces the memory space
2174 available to kernel modules from 1.5GB to 1GB.
2176 On 32-bit, the kernel physical and virtual addresses are
2177 randomized together. They will be randomized from 16MB up to
2178 512MB (8 bits of entropy).
2180 Entropy is generated using the RDRAND instruction if it is
2181 supported. If RDTSC is supported, its value is mixed into
2182 the entropy pool as well. If neither RDRAND nor RDTSC are
2183 supported, then entropy is read from the i8254 timer. The
2184 usable entropy is limited by the kernel being built using
2185 2GB addressing, and that PHYSICAL_ALIGN must be at a
2186 minimum of 2MB. As a result, only 10 bits of entropy are
2187 theoretically possible, but the implementations are further
2188 limited due to memory layouts.
2192 # Relocation on x86 needs some additional build support
2193 config X86_NEED_RELOCS
2195 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2197 config PHYSICAL_ALIGN
2198 hex "Alignment value to which kernel should be aligned"
2200 range 0x2000 0x1000000 if X86_32
2201 range 0x200000 0x1000000 if X86_64
2203 This value puts the alignment restrictions on physical address
2204 where kernel is loaded and run from. Kernel is compiled for an
2205 address which meets above alignment restriction.
2207 If bootloader loads the kernel at a non-aligned address and
2208 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2209 address aligned to above value and run from there.
2211 If bootloader loads the kernel at a non-aligned address and
2212 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2213 load address and decompress itself to the address it has been
2214 compiled for and run from there. The address for which kernel is
2215 compiled already meets above alignment restrictions. Hence the
2216 end result is that kernel runs from a physical address meeting
2217 above alignment restrictions.
2219 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2220 this value must be a multiple of 0x200000.
2222 Don't change this unless you know what you are doing.
2224 config DYNAMIC_MEMORY_LAYOUT
2227 This option makes base addresses of vmalloc and vmemmap as well as
2228 __PAGE_OFFSET movable during boot.
2230 config RANDOMIZE_MEMORY
2231 bool "Randomize the kernel memory sections"
2233 depends on RANDOMIZE_BASE
2234 select DYNAMIC_MEMORY_LAYOUT
2235 default RANDOMIZE_BASE
2237 Randomizes the base virtual address of kernel memory sections
2238 (physical memory mapping, vmalloc & vmemmap). This security feature
2239 makes exploits relying on predictable memory locations less reliable.
2241 The order of allocations remains unchanged. Entropy is generated in
2242 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2243 configuration have in average 30,000 different possible virtual
2244 addresses for each memory section.
2248 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2249 hex "Physical memory mapping padding" if EXPERT
2250 depends on RANDOMIZE_MEMORY
2251 default "0xa" if MEMORY_HOTPLUG
2253 range 0x1 0x40 if MEMORY_HOTPLUG
2256 Define the padding in terabytes added to the existing physical
2257 memory size during kernel memory randomization. It is useful
2258 for memory hotplug support but reduces the entropy available for
2259 address randomization.
2261 If unsure, leave at the default value.
2267 config BOOTPARAM_HOTPLUG_CPU0
2268 bool "Set default setting of cpu0_hotpluggable"
2269 depends on HOTPLUG_CPU
2271 Set whether default state of cpu0_hotpluggable is on or off.
2273 Say Y here to enable CPU0 hotplug by default. If this switch
2274 is turned on, there is no need to give cpu0_hotplug kernel
2275 parameter and the CPU0 hotplug feature is enabled by default.
2277 Please note: there are two known CPU0 dependencies if you want
2278 to enable the CPU0 hotplug feature either by this switch or by
2279 cpu0_hotplug kernel parameter.
2281 First, resume from hibernate or suspend always starts from CPU0.
2282 So hibernate and suspend are prevented if CPU0 is offline.
2284 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2285 offline if any interrupt can not migrate out of CPU0. There may
2286 be other CPU0 dependencies.
2288 Please make sure the dependencies are under your control before
2289 you enable this feature.
2291 Say N if you don't want to enable CPU0 hotplug feature by default.
2292 You still can enable the CPU0 hotplug feature at boot by kernel
2293 parameter cpu0_hotplug.
2295 config DEBUG_HOTPLUG_CPU0
2297 prompt "Debug CPU0 hotplug"
2298 depends on HOTPLUG_CPU
2300 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2301 soon as possible and boots up userspace with CPU0 offlined. User
2302 can online CPU0 back after boot time.
2304 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2305 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2306 compilation or giving cpu0_hotplug kernel parameter at boot.
2312 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2313 depends on COMPAT_32
2315 Certain buggy versions of glibc will crash if they are
2316 presented with a 32-bit vDSO that is not mapped at the address
2317 indicated in its segment table.
2319 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2320 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2321 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2322 the only released version with the bug, but OpenSUSE 9
2323 contains a buggy "glibc 2.3.2".
2325 The symptom of the bug is that everything crashes on startup, saying:
2326 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2328 Saying Y here changes the default value of the vdso32 boot
2329 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2330 This works around the glibc bug but hurts performance.
2332 If unsure, say N: if you are compiling your own kernel, you
2333 are unlikely to be using a buggy version of glibc.
2336 prompt "vsyscall table for legacy applications"
2338 default LEGACY_VSYSCALL_XONLY
2340 Legacy user code that does not know how to find the vDSO expects
2341 to be able to issue three syscalls by calling fixed addresses in
2342 kernel space. Since this location is not randomized with ASLR,
2343 it can be used to assist security vulnerability exploitation.
2345 This setting can be changed at boot time via the kernel command
2346 line parameter vsyscall=[emulate|xonly|none].
2348 On a system with recent enough glibc (2.14 or newer) and no
2349 static binaries, you can say None without a performance penalty
2350 to improve security.
2352 If unsure, select "Emulate execution only".
2354 config LEGACY_VSYSCALL_EMULATE
2355 bool "Full emulation"
2357 The kernel traps and emulates calls into the fixed vsyscall
2358 address mapping. This makes the mapping non-executable, but
2359 it still contains readable known contents, which could be
2360 used in certain rare security vulnerability exploits. This
2361 configuration is recommended when using legacy userspace
2362 that still uses vsyscalls along with legacy binary
2363 instrumentation tools that require code to be readable.
2365 An example of this type of legacy userspace is running
2366 Pin on an old binary that still uses vsyscalls.
2368 config LEGACY_VSYSCALL_XONLY
2369 bool "Emulate execution only"
2371 The kernel traps and emulates calls into the fixed vsyscall
2372 address mapping and does not allow reads. This
2373 configuration is recommended when userspace might use the
2374 legacy vsyscall area but support for legacy binary
2375 instrumentation of legacy code is not needed. It mitigates
2376 certain uses of the vsyscall area as an ASLR-bypassing
2379 config LEGACY_VSYSCALL_NONE
2382 There will be no vsyscall mapping at all. This will
2383 eliminate any risk of ASLR bypass due to the vsyscall
2384 fixed address mapping. Attempts to use the vsyscalls
2385 will be reported to dmesg, so that either old or
2386 malicious userspace programs can be identified.
2391 bool "Built-in kernel command line"
2393 Allow for specifying boot arguments to the kernel at
2394 build time. On some systems (e.g. embedded ones), it is
2395 necessary or convenient to provide some or all of the
2396 kernel boot arguments with the kernel itself (that is,
2397 to not rely on the boot loader to provide them.)
2399 To compile command line arguments into the kernel,
2400 set this option to 'Y', then fill in the
2401 boot arguments in CONFIG_CMDLINE.
2403 Systems with fully functional boot loaders (i.e. non-embedded)
2404 should leave this option set to 'N'.
2407 string "Built-in kernel command string"
2408 depends on CMDLINE_BOOL
2411 Enter arguments here that should be compiled into the kernel
2412 image and used at boot time. If the boot loader provides a
2413 command line at boot time, it is appended to this string to
2414 form the full kernel command line, when the system boots.
2416 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2417 change this behavior.
2419 In most cases, the command line (whether built-in or provided
2420 by the boot loader) should specify the device for the root
2423 config CMDLINE_OVERRIDE
2424 bool "Built-in command line overrides boot loader arguments"
2425 depends on CMDLINE_BOOL
2427 Set this option to 'Y' to have the kernel ignore the boot loader
2428 command line, and use ONLY the built-in command line.
2430 This is used to work around broken boot loaders. This should
2431 be set to 'N' under normal conditions.
2433 config MODIFY_LDT_SYSCALL
2434 bool "Enable the LDT (local descriptor table)" if EXPERT
2437 Linux can allow user programs to install a per-process x86
2438 Local Descriptor Table (LDT) using the modify_ldt(2) system
2439 call. This is required to run 16-bit or segmented code such as
2440 DOSEMU or some Wine programs. It is also used by some very old
2441 threading libraries.
2443 Enabling this feature adds a small amount of overhead to
2444 context switches and increases the low-level kernel attack
2445 surface. Disabling it removes the modify_ldt(2) system call.
2447 Saying 'N' here may make sense for embedded or server kernels.
2449 source "kernel/livepatch/Kconfig"
2453 config ARCH_HAS_ADD_PAGES
2455 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2457 config ARCH_ENABLE_MEMORY_HOTPLUG
2459 depends on X86_64 || (X86_32 && HIGHMEM)
2461 config ARCH_ENABLE_MEMORY_HOTREMOVE
2463 depends on MEMORY_HOTPLUG
2465 config USE_PERCPU_NUMA_NODE_ID
2469 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2471 depends on X86_64 || X86_PAE
2473 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2475 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2477 config ARCH_ENABLE_THP_MIGRATION
2479 depends on X86_64 && TRANSPARENT_HUGEPAGE
2481 menu "Power management and ACPI options"
2483 config ARCH_HIBERNATION_HEADER
2485 depends on HIBERNATION
2487 source "kernel/power/Kconfig"
2489 source "drivers/acpi/Kconfig"
2491 source "drivers/sfi/Kconfig"
2498 tristate "APM (Advanced Power Management) BIOS support"
2499 depends on X86_32 && PM_SLEEP
2501 APM is a BIOS specification for saving power using several different
2502 techniques. This is mostly useful for battery powered laptops with
2503 APM compliant BIOSes. If you say Y here, the system time will be
2504 reset after a RESUME operation, the /proc/apm device will provide
2505 battery status information, and user-space programs will receive
2506 notification of APM "events" (e.g. battery status change).
2508 If you select "Y" here, you can disable actual use of the APM
2509 BIOS by passing the "apm=off" option to the kernel at boot time.
2511 Note that the APM support is almost completely disabled for
2512 machines with more than one CPU.
2514 In order to use APM, you will need supporting software. For location
2515 and more information, read <file:Documentation/power/apm-acpi.rst>
2516 and the Battery Powered Linux mini-HOWTO, available from
2517 <http://www.tldp.org/docs.html#howto>.
2519 This driver does not spin down disk drives (see the hdparm(8)
2520 manpage ("man 8 hdparm") for that), and it doesn't turn off
2521 VESA-compliant "green" monitors.
2523 This driver does not support the TI 4000M TravelMate and the ACER
2524 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2525 desktop machines also don't have compliant BIOSes, and this driver
2526 may cause those machines to panic during the boot phase.
2528 Generally, if you don't have a battery in your machine, there isn't
2529 much point in using this driver and you should say N. If you get
2530 random kernel OOPSes or reboots that don't seem to be related to
2531 anything, try disabling/enabling this option (or disabling/enabling
2534 Some other things you should try when experiencing seemingly random,
2537 1) make sure that you have enough swap space and that it is
2539 2) pass the "no-hlt" option to the kernel
2540 3) switch on floating point emulation in the kernel and pass
2541 the "no387" option to the kernel
2542 4) pass the "floppy=nodma" option to the kernel
2543 5) pass the "mem=4M" option to the kernel (thereby disabling
2544 all but the first 4 MB of RAM)
2545 6) make sure that the CPU is not over clocked.
2546 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2547 8) disable the cache from your BIOS settings
2548 9) install a fan for the video card or exchange video RAM
2549 10) install a better fan for the CPU
2550 11) exchange RAM chips
2551 12) exchange the motherboard.
2553 To compile this driver as a module, choose M here: the
2554 module will be called apm.
2558 config APM_IGNORE_USER_SUSPEND
2559 bool "Ignore USER SUSPEND"
2561 This option will ignore USER SUSPEND requests. On machines with a
2562 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2563 series notebooks, it is necessary to say Y because of a BIOS bug.
2565 config APM_DO_ENABLE
2566 bool "Enable PM at boot time"
2568 Enable APM features at boot time. From page 36 of the APM BIOS
2569 specification: "When disabled, the APM BIOS does not automatically
2570 power manage devices, enter the Standby State, enter the Suspend
2571 State, or take power saving steps in response to CPU Idle calls."
2572 This driver will make CPU Idle calls when Linux is idle (unless this
2573 feature is turned off -- see "Do CPU IDLE calls", below). This
2574 should always save battery power, but more complicated APM features
2575 will be dependent on your BIOS implementation. You may need to turn
2576 this option off if your computer hangs at boot time when using APM
2577 support, or if it beeps continuously instead of suspending. Turn
2578 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2579 T400CDT. This is off by default since most machines do fine without
2584 bool "Make CPU Idle calls when idle"
2586 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2587 On some machines, this can activate improved power savings, such as
2588 a slowed CPU clock rate, when the machine is idle. These idle calls
2589 are made after the idle loop has run for some length of time (e.g.,
2590 333 mS). On some machines, this will cause a hang at boot time or
2591 whenever the CPU becomes idle. (On machines with more than one CPU,
2592 this option does nothing.)
2594 config APM_DISPLAY_BLANK
2595 bool "Enable console blanking using APM"
2597 Enable console blanking using the APM. Some laptops can use this to
2598 turn off the LCD backlight when the screen blanker of the Linux
2599 virtual console blanks the screen. Note that this is only used by
2600 the virtual console screen blanker, and won't turn off the backlight
2601 when using the X Window system. This also doesn't have anything to
2602 do with your VESA-compliant power-saving monitor. Further, this
2603 option doesn't work for all laptops -- it might not turn off your
2604 backlight at all, or it might print a lot of errors to the console,
2605 especially if you are using gpm.
2607 config APM_ALLOW_INTS
2608 bool "Allow interrupts during APM BIOS calls"
2610 Normally we disable external interrupts while we are making calls to
2611 the APM BIOS as a measure to lessen the effects of a badly behaving
2612 BIOS implementation. The BIOS should reenable interrupts if it
2613 needs to. Unfortunately, some BIOSes do not -- especially those in
2614 many of the newer IBM Thinkpads. If you experience hangs when you
2615 suspend, try setting this to Y. Otherwise, say N.
2619 source "drivers/cpufreq/Kconfig"
2621 source "drivers/cpuidle/Kconfig"
2623 source "drivers/idle/Kconfig"
2628 menu "Bus options (PCI etc.)"
2631 prompt "PCI access mode"
2632 depends on X86_32 && PCI
2635 On PCI systems, the BIOS can be used to detect the PCI devices and
2636 determine their configuration. However, some old PCI motherboards
2637 have BIOS bugs and may crash if this is done. Also, some embedded
2638 PCI-based systems don't have any BIOS at all. Linux can also try to
2639 detect the PCI hardware directly without using the BIOS.
2641 With this option, you can specify how Linux should detect the
2642 PCI devices. If you choose "BIOS", the BIOS will be used,
2643 if you choose "Direct", the BIOS won't be used, and if you
2644 choose "MMConfig", then PCI Express MMCONFIG will be used.
2645 If you choose "Any", the kernel will try MMCONFIG, then the
2646 direct access method and falls back to the BIOS if that doesn't
2647 work. If unsure, go with the default, which is "Any".
2652 config PCI_GOMMCONFIG
2669 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2671 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2674 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2677 bool "Support mmconfig PCI config space access" if X86_64
2679 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2680 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2684 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2688 depends on PCI && XEN
2691 config MMCONF_FAM10H
2693 depends on X86_64 && PCI_MMCONFIG && ACPI
2695 config PCI_CNB20LE_QUIRK
2696 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2699 Read the PCI windows out of the CNB20LE host bridge. This allows
2700 PCI hotplug to work on systems with the CNB20LE chipset which do
2703 There's no public spec for this chipset, and this functionality
2704 is known to be incomplete.
2706 You should say N unless you know you need this.
2709 bool "ISA bus support on modern systems" if EXPERT
2711 Expose ISA bus device drivers and options available for selection and
2712 configuration. Enable this option if your target machine has an ISA
2713 bus. ISA is an older system, displaced by PCI and newer bus
2714 architectures -- if your target machine is modern, it probably does
2715 not have an ISA bus.
2719 # x86_64 have no ISA slots, but can have ISA-style DMA.
2721 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2724 Enables ISA-style DMA support for devices requiring such controllers.
2732 Find out whether you have ISA slots on your motherboard. ISA is the
2733 name of a bus system, i.e. the way the CPU talks to the other stuff
2734 inside your box. Other bus systems are PCI, EISA, MicroChannel
2735 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2736 newer boards don't support it. If you have ISA, say Y, otherwise N.
2739 tristate "NatSemi SCx200 support"
2741 This provides basic support for National Semiconductor's
2742 (now AMD's) Geode processors. The driver probes for the
2743 PCI-IDs of several on-chip devices, so its a good dependency
2744 for other scx200_* drivers.
2746 If compiled as a module, the driver is named scx200.
2748 config SCx200HR_TIMER
2749 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2753 This driver provides a clocksource built upon the on-chip
2754 27MHz high-resolution timer. Its also a workaround for
2755 NSC Geode SC-1100's buggy TSC, which loses time when the
2756 processor goes idle (as is done by the scheduler). The
2757 other workaround is idle=poll boot option.
2760 bool "One Laptop Per Child support"
2768 Add support for detecting the unique features of the OLPC
2772 bool "OLPC XO-1 Power Management"
2773 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2775 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2778 bool "OLPC XO-1 Real Time Clock"
2779 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2781 Add support for the XO-1 real time clock, which can be used as a
2782 programmable wakeup source.
2785 bool "OLPC XO-1 SCI extras"
2786 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2790 Add support for SCI-based features of the OLPC XO-1 laptop:
2791 - EC-driven system wakeups
2795 - AC adapter status updates
2796 - Battery status updates
2798 config OLPC_XO15_SCI
2799 bool "OLPC XO-1.5 SCI extras"
2800 depends on OLPC && ACPI
2803 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2804 - EC-driven system wakeups
2805 - AC adapter status updates
2806 - Battery status updates
2809 bool "PCEngines ALIX System Support (LED setup)"
2812 This option enables system support for the PCEngines ALIX.
2813 At present this just sets up LEDs for GPIO control on
2814 ALIX2/3/6 boards. However, other system specific setup should
2817 Note: You must still enable the drivers for GPIO and LED support
2818 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2820 Note: You have to set alix.force=1 for boards with Award BIOS.
2823 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2826 This option enables system support for the Soekris Engineering net5501.
2829 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2833 This option enables system support for the Traverse Technologies GEOS.
2836 bool "Technologic Systems TS-5500 platform support"
2838 select CHECK_SIGNATURE
2842 This option enables system support for the Technologic Systems TS-5500.
2848 depends on CPU_SUP_AMD && PCI
2851 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2853 Firmwares often provide initial graphics framebuffers so the BIOS,
2854 bootloader or kernel can show basic video-output during boot for
2855 user-guidance and debugging. Historically, x86 used the VESA BIOS
2856 Extensions and EFI-framebuffers for this, which are mostly limited
2858 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2859 framebuffers so the new generic system-framebuffer drivers can be
2860 used on x86. If the framebuffer is not compatible with the generic
2861 modes, it is advertised as fallback platform framebuffer so legacy
2862 drivers like efifb, vesafb and uvesafb can pick it up.
2863 If this option is not selected, all system framebuffers are always
2864 marked as fallback platform framebuffers as usual.
2866 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2867 not be able to pick up generic system framebuffers if this option
2868 is selected. You are highly encouraged to enable simplefb as
2869 replacement if you select this option. simplefb can correctly deal
2870 with generic system framebuffers. But you should still keep vesafb
2871 and others enabled as fallback if a system framebuffer is
2872 incompatible with simplefb.
2879 menu "Binary Emulations"
2881 config IA32_EMULATION
2882 bool "IA32 Emulation"
2884 select ARCH_WANT_OLD_COMPAT_IPC
2886 select COMPAT_BINFMT_ELF
2887 select COMPAT_OLD_SIGACTION
2889 Include code to run legacy 32-bit programs under a
2890 64-bit kernel. You should likely turn this on, unless you're
2891 100% sure that you don't have any 32-bit programs left.
2894 tristate "IA32 a.out support"
2895 depends on IA32_EMULATION
2898 Support old a.out binaries in the 32bit emulation.
2901 bool "x32 ABI for 64-bit mode"
2904 Include code to run binaries for the x32 native 32-bit ABI
2905 for 64-bit processors. An x32 process gets access to the
2906 full 64-bit register file and wide data path while leaving
2907 pointers at 32 bits for smaller memory footprint.
2909 You will need a recent binutils (2.22 or later) with
2910 elf32_x86_64 support enabled to compile a kernel with this
2915 depends on IA32_EMULATION || X86_32
2917 select OLD_SIGSUSPEND3
2921 depends on IA32_EMULATION || X86_X32
2924 config COMPAT_FOR_U64_ALIGNMENT
2927 config SYSVIPC_COMPAT
2935 config HAVE_ATOMIC_IOMAP
2939 config X86_DEV_DMA_OPS
2942 source "drivers/firmware/Kconfig"
2944 source "arch/x86/kvm/Kconfig"