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"
1466 select DYNAMIC_MEMORY_LAYOUT
1467 select SPARSEMEM_VMEMMAP
1470 5-level paging enables access to larger address space:
1471 upto 128 PiB of virtual address space and 4 PiB of
1472 physical address space.
1474 It will be supported by future Intel CPUs.
1476 A kernel with the option enabled can be booted on machines that
1477 support 4- or 5-level paging.
1479 See Documentation/x86/x86_64/5level-paging.rst for more
1484 config X86_DIRECT_GBPAGES
1488 Certain kernel features effectively disable kernel
1489 linear 1 GB mappings (even if the CPU otherwise
1490 supports them), so don't confuse the user by printing
1491 that we have them enabled.
1493 config X86_CPA_STATISTICS
1494 bool "Enable statistic for Change Page Attribute"
1497 Expose statistics about the Change Page Attribute mechanims, which
1498 helps to determine the effectiveness of preserving large and huge
1499 page mappings when mapping protections are changed.
1501 config AMD_MEM_ENCRYPT
1502 bool "AMD Secure Memory Encryption (SME) support"
1503 depends on X86_64 && CPU_SUP_AMD
1504 select DYNAMIC_PHYSICAL_MASK
1505 select ARCH_USE_MEMREMAP_PROT
1506 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1508 Say yes to enable support for the encryption of system memory.
1509 This requires an AMD processor that supports Secure Memory
1512 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1513 bool "Activate AMD Secure Memory Encryption (SME) by default"
1515 depends on AMD_MEM_ENCRYPT
1517 Say yes to have system memory encrypted by default if running on
1518 an AMD processor that supports Secure Memory Encryption (SME).
1520 If set to Y, then the encryption of system memory can be
1521 deactivated with the mem_encrypt=off command line option.
1523 If set to N, then the encryption of system memory can be
1524 activated with the mem_encrypt=on command line option.
1526 # Common NUMA Features
1528 bool "Numa Memory Allocation and Scheduler Support"
1530 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1531 default y if X86_BIGSMP
1533 Enable NUMA (Non Uniform Memory Access) support.
1535 The kernel will try to allocate memory used by a CPU on the
1536 local memory controller of the CPU and add some more
1537 NUMA awareness to the kernel.
1539 For 64-bit this is recommended if the system is Intel Core i7
1540 (or later), AMD Opteron, or EM64T NUMA.
1542 For 32-bit this is only needed if you boot a 32-bit
1543 kernel on a 64-bit NUMA platform.
1545 Otherwise, you should say N.
1549 prompt "Old style AMD Opteron NUMA detection"
1550 depends on X86_64 && NUMA && PCI
1552 Enable AMD NUMA node topology detection. You should say Y here if
1553 you have a multi processor AMD system. This uses an old method to
1554 read the NUMA configuration directly from the builtin Northbridge
1555 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1556 which also takes priority if both are compiled in.
1558 config X86_64_ACPI_NUMA
1560 prompt "ACPI NUMA detection"
1561 depends on X86_64 && NUMA && ACPI && PCI
1564 Enable ACPI SRAT based node topology detection.
1566 # Some NUMA nodes have memory ranges that span
1567 # other nodes. Even though a pfn is valid and
1568 # between a node's start and end pfns, it may not
1569 # reside on that node. See memmap_init_zone()
1571 config NODES_SPAN_OTHER_NODES
1573 depends on X86_64_ACPI_NUMA
1576 bool "NUMA emulation"
1579 Enable NUMA emulation. A flat machine will be split
1580 into virtual nodes when booted with "numa=fake=N", where N is the
1581 number of nodes. This is only useful for debugging.
1584 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1586 default "10" if MAXSMP
1587 default "6" if X86_64
1589 depends on NEED_MULTIPLE_NODES
1591 Specify the maximum number of NUMA Nodes available on the target
1592 system. Increases memory reserved to accommodate various tables.
1594 config ARCH_HAVE_MEMORY_PRESENT
1596 depends on X86_32 && DISCONTIGMEM
1598 config ARCH_FLATMEM_ENABLE
1600 depends on X86_32 && !NUMA
1602 config ARCH_DISCONTIGMEM_ENABLE
1604 depends on NUMA && X86_32
1607 config ARCH_SPARSEMEM_ENABLE
1609 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1610 select SPARSEMEM_STATIC if X86_32
1611 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1613 config ARCH_SPARSEMEM_DEFAULT
1614 def_bool X86_64 || (NUMA && X86_32)
1616 config ARCH_SELECT_MEMORY_MODEL
1618 depends on ARCH_SPARSEMEM_ENABLE
1620 config ARCH_MEMORY_PROBE
1621 bool "Enable sysfs memory/probe interface"
1622 depends on X86_64 && MEMORY_HOTPLUG
1624 This option enables a sysfs memory/probe interface for testing.
1625 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1626 If you are unsure how to answer this question, answer N.
1628 config ARCH_PROC_KCORE_TEXT
1630 depends on X86_64 && PROC_KCORE
1632 config ILLEGAL_POINTER_VALUE
1635 default 0xdead000000000000 if X86_64
1637 config X86_PMEM_LEGACY_DEVICE
1640 config X86_PMEM_LEGACY
1641 tristate "Support non-standard NVDIMMs and ADR protected memory"
1642 depends on PHYS_ADDR_T_64BIT
1644 select X86_PMEM_LEGACY_DEVICE
1647 Treat memory marked using the non-standard e820 type of 12 as used
1648 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1649 The kernel will offer these regions to the 'pmem' driver so
1650 they can be used for persistent storage.
1655 bool "Allocate 3rd-level pagetables from highmem"
1658 The VM uses one page table entry for each page of physical memory.
1659 For systems with a lot of RAM, this can be wasteful of precious
1660 low memory. Setting this option will put user-space page table
1661 entries in high memory.
1663 config X86_CHECK_BIOS_CORRUPTION
1664 bool "Check for low memory corruption"
1666 Periodically check for memory corruption in low memory, which
1667 is suspected to be caused by BIOS. Even when enabled in the
1668 configuration, it is disabled at runtime. Enable it by
1669 setting "memory_corruption_check=1" on the kernel command
1670 line. By default it scans the low 64k of memory every 60
1671 seconds; see the memory_corruption_check_size and
1672 memory_corruption_check_period parameters in
1673 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1675 When enabled with the default parameters, this option has
1676 almost no overhead, as it reserves a relatively small amount
1677 of memory and scans it infrequently. It both detects corruption
1678 and prevents it from affecting the running system.
1680 It is, however, intended as a diagnostic tool; if repeatable
1681 BIOS-originated corruption always affects the same memory,
1682 you can use memmap= to prevent the kernel from using that
1685 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1686 bool "Set the default setting of memory_corruption_check"
1687 depends on X86_CHECK_BIOS_CORRUPTION
1690 Set whether the default state of memory_corruption_check is
1693 config X86_RESERVE_LOW
1694 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1698 Specify the amount of low memory to reserve for the BIOS.
1700 The first page contains BIOS data structures that the kernel
1701 must not use, so that page must always be reserved.
1703 By default we reserve the first 64K of physical RAM, as a
1704 number of BIOSes are known to corrupt that memory range
1705 during events such as suspend/resume or monitor cable
1706 insertion, so it must not be used by the kernel.
1708 You can set this to 4 if you are absolutely sure that you
1709 trust the BIOS to get all its memory reservations and usages
1710 right. If you know your BIOS have problems beyond the
1711 default 64K area, you can set this to 640 to avoid using the
1712 entire low memory range.
1714 If you have doubts about the BIOS (e.g. suspend/resume does
1715 not work or there's kernel crashes after certain hardware
1716 hotplug events) then you might want to enable
1717 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1718 typical corruption patterns.
1720 Leave this to the default value of 64 if you are unsure.
1722 config MATH_EMULATION
1724 depends on MODIFY_LDT_SYSCALL
1725 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1727 Linux can emulate a math coprocessor (used for floating point
1728 operations) if you don't have one. 486DX and Pentium processors have
1729 a math coprocessor built in, 486SX and 386 do not, unless you added
1730 a 487DX or 387, respectively. (The messages during boot time can
1731 give you some hints here ["man dmesg"].) Everyone needs either a
1732 coprocessor or this emulation.
1734 If you don't have a math coprocessor, you need to say Y here; if you
1735 say Y here even though you have a coprocessor, the coprocessor will
1736 be used nevertheless. (This behavior can be changed with the kernel
1737 command line option "no387", which comes handy if your coprocessor
1738 is broken. Try "man bootparam" or see the documentation of your boot
1739 loader (lilo or loadlin) about how to pass options to the kernel at
1740 boot time.) This means that it is a good idea to say Y here if you
1741 intend to use this kernel on different machines.
1743 More information about the internals of the Linux math coprocessor
1744 emulation can be found in <file:arch/x86/math-emu/README>.
1746 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1747 kernel, it won't hurt.
1751 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1753 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1754 the Memory Type Range Registers (MTRRs) may be used to control
1755 processor access to memory ranges. This is most useful if you have
1756 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1757 allows bus write transfers to be combined into a larger transfer
1758 before bursting over the PCI/AGP bus. This can increase performance
1759 of image write operations 2.5 times or more. Saying Y here creates a
1760 /proc/mtrr file which may be used to manipulate your processor's
1761 MTRRs. Typically the X server should use this.
1763 This code has a reasonably generic interface so that similar
1764 control registers on other processors can be easily supported
1767 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1768 Registers (ARRs) which provide a similar functionality to MTRRs. For
1769 these, the ARRs are used to emulate the MTRRs.
1770 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1771 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1772 write-combining. All of these processors are supported by this code
1773 and it makes sense to say Y here if you have one of them.
1775 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1776 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1777 can lead to all sorts of problems, so it's good to say Y here.
1779 You can safely say Y even if your machine doesn't have MTRRs, you'll
1780 just add about 9 KB to your kernel.
1782 See <file:Documentation/x86/mtrr.rst> for more information.
1784 config MTRR_SANITIZER
1786 prompt "MTRR cleanup support"
1789 Convert MTRR layout from continuous to discrete, so X drivers can
1790 add writeback entries.
1792 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1793 The largest mtrr entry size for a continuous block can be set with
1798 config MTRR_SANITIZER_ENABLE_DEFAULT
1799 int "MTRR cleanup enable value (0-1)"
1802 depends on MTRR_SANITIZER
1804 Enable mtrr cleanup default value
1806 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1807 int "MTRR cleanup spare reg num (0-7)"
1810 depends on MTRR_SANITIZER
1812 mtrr cleanup spare entries default, it can be changed via
1813 mtrr_spare_reg_nr=N on the kernel command line.
1817 prompt "x86 PAT support" if EXPERT
1820 Use PAT attributes to setup page level cache control.
1822 PATs are the modern equivalents of MTRRs and are much more
1823 flexible than MTRRs.
1825 Say N here if you see bootup problems (boot crash, boot hang,
1826 spontaneous reboots) or a non-working video driver.
1830 config ARCH_USES_PG_UNCACHED
1836 prompt "x86 architectural random number generator" if EXPERT
1838 Enable the x86 architectural RDRAND instruction
1839 (Intel Bull Mountain technology) to generate random numbers.
1840 If supported, this is a high bandwidth, cryptographically
1841 secure hardware random number generator.
1845 prompt "Supervisor Mode Access Prevention" if EXPERT
1847 Supervisor Mode Access Prevention (SMAP) is a security
1848 feature in newer Intel processors. There is a small
1849 performance cost if this enabled and turned on; there is
1850 also a small increase in the kernel size if this is enabled.
1856 depends on CPU_SUP_INTEL || CPU_SUP_AMD
1857 prompt "User Mode Instruction Prevention" if EXPERT
1859 User Mode Instruction Prevention (UMIP) is a security feature in
1860 some x86 processors. If enabled, a general protection fault is
1861 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1862 executed in user mode. These instructions unnecessarily expose
1863 information about the hardware state.
1865 The vast majority of applications do not use these instructions.
1866 For the very few that do, software emulation is provided in
1867 specific cases in protected and virtual-8086 modes. Emulated
1870 config X86_INTEL_MPX
1871 prompt "Intel MPX (Memory Protection Extensions)"
1873 # Note: only available in 64-bit mode due to VMA flags shortage
1874 depends on CPU_SUP_INTEL && X86_64
1875 select ARCH_USES_HIGH_VMA_FLAGS
1877 MPX provides hardware features that can be used in
1878 conjunction with compiler-instrumented code to check
1879 memory references. It is designed to detect buffer
1880 overflow or underflow bugs.
1882 This option enables running applications which are
1883 instrumented or otherwise use MPX. It does not use MPX
1884 itself inside the kernel or to protect the kernel
1885 against bad memory references.
1887 Enabling this option will make the kernel larger:
1888 ~8k of kernel text and 36 bytes of data on a 64-bit
1889 defconfig. It adds a long to the 'mm_struct' which
1890 will increase the kernel memory overhead of each
1891 process and adds some branches to paths used during
1892 exec() and munmap().
1894 For details, see Documentation/x86/intel_mpx.rst
1898 config X86_INTEL_MEMORY_PROTECTION_KEYS
1899 prompt "Intel Memory Protection Keys"
1901 # Note: only available in 64-bit mode
1902 depends on CPU_SUP_INTEL && X86_64
1903 select ARCH_USES_HIGH_VMA_FLAGS
1904 select ARCH_HAS_PKEYS
1906 Memory Protection Keys provides a mechanism for enforcing
1907 page-based protections, but without requiring modification of the
1908 page tables when an application changes protection domains.
1910 For details, see Documentation/core-api/protection-keys.rst
1915 prompt "TSX enable mode"
1916 depends on CPU_SUP_INTEL
1917 default X86_INTEL_TSX_MODE_OFF
1919 Intel's TSX (Transactional Synchronization Extensions) feature
1920 allows to optimize locking protocols through lock elision which
1921 can lead to a noticeable performance boost.
1923 On the other hand it has been shown that TSX can be exploited
1924 to form side channel attacks (e.g. TAA) and chances are there
1925 will be more of those attacks discovered in the future.
1927 Therefore TSX is not enabled by default (aka tsx=off). An admin
1928 might override this decision by tsx=on the command line parameter.
1929 Even with TSX enabled, the kernel will attempt to enable the best
1930 possible TAA mitigation setting depending on the microcode available
1931 for the particular machine.
1933 This option allows to set the default tsx mode between tsx=on, =off
1934 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1937 Say off if not sure, auto if TSX is in use but it should be used on safe
1938 platforms or on if TSX is in use and the security aspect of tsx is not
1941 config X86_INTEL_TSX_MODE_OFF
1944 TSX is disabled if possible - equals to tsx=off command line parameter.
1946 config X86_INTEL_TSX_MODE_ON
1949 TSX is always enabled on TSX capable HW - equals the tsx=on command
1952 config X86_INTEL_TSX_MODE_AUTO
1955 TSX is enabled on TSX capable HW that is believed to be safe against
1956 side channel attacks- equals the tsx=auto command line parameter.
1960 bool "EFI runtime service support"
1963 select EFI_RUNTIME_WRAPPERS
1965 This enables the kernel to use EFI runtime services that are
1966 available (such as the EFI variable services).
1968 This option is only useful on systems that have EFI firmware.
1969 In addition, you should use the latest ELILO loader available
1970 at <http://elilo.sourceforge.net> in order to take advantage
1971 of EFI runtime services. However, even with this option, the
1972 resultant kernel should continue to boot on existing non-EFI
1976 bool "EFI stub support"
1977 depends on EFI && !X86_USE_3DNOW
1980 This kernel feature allows a bzImage to be loaded directly
1981 by EFI firmware without the use of a bootloader.
1983 See Documentation/admin-guide/efi-stub.rst for more information.
1986 bool "EFI mixed-mode support"
1987 depends on EFI_STUB && X86_64
1989 Enabling this feature allows a 64-bit kernel to be booted
1990 on a 32-bit firmware, provided that your CPU supports 64-bit
1993 Note that it is not possible to boot a mixed-mode enabled
1994 kernel via the EFI boot stub - a bootloader that supports
1995 the EFI handover protocol must be used.
2001 prompt "Enable seccomp to safely compute untrusted bytecode"
2003 This kernel feature is useful for number crunching applications
2004 that may need to compute untrusted bytecode during their
2005 execution. By using pipes or other transports made available to
2006 the process as file descriptors supporting the read/write
2007 syscalls, it's possible to isolate those applications in
2008 their own address space using seccomp. Once seccomp is
2009 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
2010 and the task is only allowed to execute a few safe syscalls
2011 defined by each seccomp mode.
2013 If unsure, say Y. Only embedded should say N here.
2015 source "kernel/Kconfig.hz"
2018 bool "kexec system call"
2021 kexec is a system call that implements the ability to shutdown your
2022 current kernel, and to start another kernel. It is like a reboot
2023 but it is independent of the system firmware. And like a reboot
2024 you can start any kernel with it, not just Linux.
2026 The name comes from the similarity to the exec system call.
2028 It is an ongoing process to be certain the hardware in a machine
2029 is properly shutdown, so do not be surprised if this code does not
2030 initially work for you. As of this writing the exact hardware
2031 interface is strongly in flux, so no good recommendation can be
2035 bool "kexec file based system call"
2040 depends on CRYPTO_SHA256=y
2042 This is new version of kexec system call. This system call is
2043 file based and takes file descriptors as system call argument
2044 for kernel and initramfs as opposed to list of segments as
2045 accepted by previous system call.
2047 config ARCH_HAS_KEXEC_PURGATORY
2051 bool "Verify kernel signature during kexec_file_load() syscall"
2052 depends on KEXEC_FILE
2055 This option makes the kexec_file_load() syscall check for a valid
2056 signature of the kernel image. The image can still be loaded without
2057 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2058 there's a signature that we can check, then it must be valid.
2060 In addition to this option, you need to enable signature
2061 verification for the corresponding kernel image type being
2062 loaded in order for this to work.
2064 config KEXEC_SIG_FORCE
2065 bool "Require a valid signature in kexec_file_load() syscall"
2066 depends on KEXEC_SIG
2068 This option makes kernel signature verification mandatory for
2069 the kexec_file_load() syscall.
2071 config KEXEC_BZIMAGE_VERIFY_SIG
2072 bool "Enable bzImage signature verification support"
2073 depends on KEXEC_SIG
2074 depends on SIGNED_PE_FILE_VERIFICATION
2075 select SYSTEM_TRUSTED_KEYRING
2077 Enable bzImage signature verification support.
2080 bool "kernel crash dumps"
2081 depends on X86_64 || (X86_32 && HIGHMEM)
2083 Generate crash dump after being started by kexec.
2084 This should be normally only set in special crash dump kernels
2085 which are loaded in the main kernel with kexec-tools into
2086 a specially reserved region and then later executed after
2087 a crash by kdump/kexec. The crash dump kernel must be compiled
2088 to a memory address not used by the main kernel or BIOS using
2089 PHYSICAL_START, or it must be built as a relocatable image
2090 (CONFIG_RELOCATABLE=y).
2091 For more details see Documentation/admin-guide/kdump/kdump.rst
2095 depends on KEXEC && HIBERNATION
2097 Jump between original kernel and kexeced kernel and invoke
2098 code in physical address mode via KEXEC
2100 config PHYSICAL_START
2101 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2104 This gives the physical address where the kernel is loaded.
2106 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2107 bzImage will decompress itself to above physical address and
2108 run from there. Otherwise, bzImage will run from the address where
2109 it has been loaded by the boot loader and will ignore above physical
2112 In normal kdump cases one does not have to set/change this option
2113 as now bzImage can be compiled as a completely relocatable image
2114 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2115 address. This option is mainly useful for the folks who don't want
2116 to use a bzImage for capturing the crash dump and want to use a
2117 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2118 to be specifically compiled to run from a specific memory area
2119 (normally a reserved region) and this option comes handy.
2121 So if you are using bzImage for capturing the crash dump,
2122 leave the value here unchanged to 0x1000000 and set
2123 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2124 for capturing the crash dump change this value to start of
2125 the reserved region. In other words, it can be set based on
2126 the "X" value as specified in the "crashkernel=YM@XM"
2127 command line boot parameter passed to the panic-ed
2128 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2129 for more details about crash dumps.
2131 Usage of bzImage for capturing the crash dump is recommended as
2132 one does not have to build two kernels. Same kernel can be used
2133 as production kernel and capture kernel. Above option should have
2134 gone away after relocatable bzImage support is introduced. But it
2135 is present because there are users out there who continue to use
2136 vmlinux for dump capture. This option should go away down the
2139 Don't change this unless you know what you are doing.
2142 bool "Build a relocatable kernel"
2145 This builds a kernel image that retains relocation information
2146 so it can be loaded someplace besides the default 1MB.
2147 The relocations tend to make the kernel binary about 10% larger,
2148 but are discarded at runtime.
2150 One use is for the kexec on panic case where the recovery kernel
2151 must live at a different physical address than the primary
2154 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2155 it has been loaded at and the compile time physical address
2156 (CONFIG_PHYSICAL_START) is used as the minimum location.
2158 config RANDOMIZE_BASE
2159 bool "Randomize the address of the kernel image (KASLR)"
2160 depends on RELOCATABLE
2163 In support of Kernel Address Space Layout Randomization (KASLR),
2164 this randomizes the physical address at which the kernel image
2165 is decompressed and the virtual address where the kernel
2166 image is mapped, as a security feature that deters exploit
2167 attempts relying on knowledge of the location of kernel
2170 On 64-bit, the kernel physical and virtual addresses are
2171 randomized separately. The physical address will be anywhere
2172 between 16MB and the top of physical memory (up to 64TB). The
2173 virtual address will be randomized from 16MB up to 1GB (9 bits
2174 of entropy). Note that this also reduces the memory space
2175 available to kernel modules from 1.5GB to 1GB.
2177 On 32-bit, the kernel physical and virtual addresses are
2178 randomized together. They will be randomized from 16MB up to
2179 512MB (8 bits of entropy).
2181 Entropy is generated using the RDRAND instruction if it is
2182 supported. If RDTSC is supported, its value is mixed into
2183 the entropy pool as well. If neither RDRAND nor RDTSC are
2184 supported, then entropy is read from the i8254 timer. The
2185 usable entropy is limited by the kernel being built using
2186 2GB addressing, and that PHYSICAL_ALIGN must be at a
2187 minimum of 2MB. As a result, only 10 bits of entropy are
2188 theoretically possible, but the implementations are further
2189 limited due to memory layouts.
2193 # Relocation on x86 needs some additional build support
2194 config X86_NEED_RELOCS
2196 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2198 config PHYSICAL_ALIGN
2199 hex "Alignment value to which kernel should be aligned"
2201 range 0x2000 0x1000000 if X86_32
2202 range 0x200000 0x1000000 if X86_64
2204 This value puts the alignment restrictions on physical address
2205 where kernel is loaded and run from. Kernel is compiled for an
2206 address which meets above alignment restriction.
2208 If bootloader loads the kernel at a non-aligned address and
2209 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2210 address aligned to above value and run from there.
2212 If bootloader loads the kernel at a non-aligned address and
2213 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2214 load address and decompress itself to the address it has been
2215 compiled for and run from there. The address for which kernel is
2216 compiled already meets above alignment restrictions. Hence the
2217 end result is that kernel runs from a physical address meeting
2218 above alignment restrictions.
2220 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2221 this value must be a multiple of 0x200000.
2223 Don't change this unless you know what you are doing.
2225 config DYNAMIC_MEMORY_LAYOUT
2228 This option makes base addresses of vmalloc and vmemmap as well as
2229 __PAGE_OFFSET movable during boot.
2231 config RANDOMIZE_MEMORY
2232 bool "Randomize the kernel memory sections"
2234 depends on RANDOMIZE_BASE
2235 select DYNAMIC_MEMORY_LAYOUT
2236 default RANDOMIZE_BASE
2238 Randomizes the base virtual address of kernel memory sections
2239 (physical memory mapping, vmalloc & vmemmap). This security feature
2240 makes exploits relying on predictable memory locations less reliable.
2242 The order of allocations remains unchanged. Entropy is generated in
2243 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2244 configuration have in average 30,000 different possible virtual
2245 addresses for each memory section.
2249 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2250 hex "Physical memory mapping padding" if EXPERT
2251 depends on RANDOMIZE_MEMORY
2252 default "0xa" if MEMORY_HOTPLUG
2254 range 0x1 0x40 if MEMORY_HOTPLUG
2257 Define the padding in terabytes added to the existing physical
2258 memory size during kernel memory randomization. It is useful
2259 for memory hotplug support but reduces the entropy available for
2260 address randomization.
2262 If unsure, leave at the default value.
2268 config BOOTPARAM_HOTPLUG_CPU0
2269 bool "Set default setting of cpu0_hotpluggable"
2270 depends on HOTPLUG_CPU
2272 Set whether default state of cpu0_hotpluggable is on or off.
2274 Say Y here to enable CPU0 hotplug by default. If this switch
2275 is turned on, there is no need to give cpu0_hotplug kernel
2276 parameter and the CPU0 hotplug feature is enabled by default.
2278 Please note: there are two known CPU0 dependencies if you want
2279 to enable the CPU0 hotplug feature either by this switch or by
2280 cpu0_hotplug kernel parameter.
2282 First, resume from hibernate or suspend always starts from CPU0.
2283 So hibernate and suspend are prevented if CPU0 is offline.
2285 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2286 offline if any interrupt can not migrate out of CPU0. There may
2287 be other CPU0 dependencies.
2289 Please make sure the dependencies are under your control before
2290 you enable this feature.
2292 Say N if you don't want to enable CPU0 hotplug feature by default.
2293 You still can enable the CPU0 hotplug feature at boot by kernel
2294 parameter cpu0_hotplug.
2296 config DEBUG_HOTPLUG_CPU0
2298 prompt "Debug CPU0 hotplug"
2299 depends on HOTPLUG_CPU
2301 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2302 soon as possible and boots up userspace with CPU0 offlined. User
2303 can online CPU0 back after boot time.
2305 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2306 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2307 compilation or giving cpu0_hotplug kernel parameter at boot.
2313 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2314 depends on COMPAT_32
2316 Certain buggy versions of glibc will crash if they are
2317 presented with a 32-bit vDSO that is not mapped at the address
2318 indicated in its segment table.
2320 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2321 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2322 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2323 the only released version with the bug, but OpenSUSE 9
2324 contains a buggy "glibc 2.3.2".
2326 The symptom of the bug is that everything crashes on startup, saying:
2327 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2329 Saying Y here changes the default value of the vdso32 boot
2330 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2331 This works around the glibc bug but hurts performance.
2333 If unsure, say N: if you are compiling your own kernel, you
2334 are unlikely to be using a buggy version of glibc.
2337 prompt "vsyscall table for legacy applications"
2339 default LEGACY_VSYSCALL_XONLY
2341 Legacy user code that does not know how to find the vDSO expects
2342 to be able to issue three syscalls by calling fixed addresses in
2343 kernel space. Since this location is not randomized with ASLR,
2344 it can be used to assist security vulnerability exploitation.
2346 This setting can be changed at boot time via the kernel command
2347 line parameter vsyscall=[emulate|xonly|none].
2349 On a system with recent enough glibc (2.14 or newer) and no
2350 static binaries, you can say None without a performance penalty
2351 to improve security.
2353 If unsure, select "Emulate execution only".
2355 config LEGACY_VSYSCALL_EMULATE
2356 bool "Full emulation"
2358 The kernel traps and emulates calls into the fixed vsyscall
2359 address mapping. This makes the mapping non-executable, but
2360 it still contains readable known contents, which could be
2361 used in certain rare security vulnerability exploits. This
2362 configuration is recommended when using legacy userspace
2363 that still uses vsyscalls along with legacy binary
2364 instrumentation tools that require code to be readable.
2366 An example of this type of legacy userspace is running
2367 Pin on an old binary that still uses vsyscalls.
2369 config LEGACY_VSYSCALL_XONLY
2370 bool "Emulate execution only"
2372 The kernel traps and emulates calls into the fixed vsyscall
2373 address mapping and does not allow reads. This
2374 configuration is recommended when userspace might use the
2375 legacy vsyscall area but support for legacy binary
2376 instrumentation of legacy code is not needed. It mitigates
2377 certain uses of the vsyscall area as an ASLR-bypassing
2380 config LEGACY_VSYSCALL_NONE
2383 There will be no vsyscall mapping at all. This will
2384 eliminate any risk of ASLR bypass due to the vsyscall
2385 fixed address mapping. Attempts to use the vsyscalls
2386 will be reported to dmesg, so that either old or
2387 malicious userspace programs can be identified.
2392 bool "Built-in kernel command line"
2394 Allow for specifying boot arguments to the kernel at
2395 build time. On some systems (e.g. embedded ones), it is
2396 necessary or convenient to provide some or all of the
2397 kernel boot arguments with the kernel itself (that is,
2398 to not rely on the boot loader to provide them.)
2400 To compile command line arguments into the kernel,
2401 set this option to 'Y', then fill in the
2402 boot arguments in CONFIG_CMDLINE.
2404 Systems with fully functional boot loaders (i.e. non-embedded)
2405 should leave this option set to 'N'.
2408 string "Built-in kernel command string"
2409 depends on CMDLINE_BOOL
2412 Enter arguments here that should be compiled into the kernel
2413 image and used at boot time. If the boot loader provides a
2414 command line at boot time, it is appended to this string to
2415 form the full kernel command line, when the system boots.
2417 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2418 change this behavior.
2420 In most cases, the command line (whether built-in or provided
2421 by the boot loader) should specify the device for the root
2424 config CMDLINE_OVERRIDE
2425 bool "Built-in command line overrides boot loader arguments"
2426 depends on CMDLINE_BOOL
2428 Set this option to 'Y' to have the kernel ignore the boot loader
2429 command line, and use ONLY the built-in command line.
2431 This is used to work around broken boot loaders. This should
2432 be set to 'N' under normal conditions.
2434 config MODIFY_LDT_SYSCALL
2435 bool "Enable the LDT (local descriptor table)" if EXPERT
2438 Linux can allow user programs to install a per-process x86
2439 Local Descriptor Table (LDT) using the modify_ldt(2) system
2440 call. This is required to run 16-bit or segmented code such as
2441 DOSEMU or some Wine programs. It is also used by some very old
2442 threading libraries.
2444 Enabling this feature adds a small amount of overhead to
2445 context switches and increases the low-level kernel attack
2446 surface. Disabling it removes the modify_ldt(2) system call.
2448 Saying 'N' here may make sense for embedded or server kernels.
2450 source "kernel/livepatch/Kconfig"
2454 config ARCH_HAS_ADD_PAGES
2456 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2458 config ARCH_ENABLE_MEMORY_HOTPLUG
2460 depends on X86_64 || (X86_32 && HIGHMEM)
2462 config ARCH_ENABLE_MEMORY_HOTREMOVE
2464 depends on MEMORY_HOTPLUG
2466 config USE_PERCPU_NUMA_NODE_ID
2470 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2472 depends on X86_64 || X86_PAE
2474 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2476 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2478 config ARCH_ENABLE_THP_MIGRATION
2480 depends on X86_64 && TRANSPARENT_HUGEPAGE
2482 menu "Power management and ACPI options"
2484 config ARCH_HIBERNATION_HEADER
2486 depends on HIBERNATION
2488 source "kernel/power/Kconfig"
2490 source "drivers/acpi/Kconfig"
2492 source "drivers/sfi/Kconfig"
2499 tristate "APM (Advanced Power Management) BIOS support"
2500 depends on X86_32 && PM_SLEEP
2502 APM is a BIOS specification for saving power using several different
2503 techniques. This is mostly useful for battery powered laptops with
2504 APM compliant BIOSes. If you say Y here, the system time will be
2505 reset after a RESUME operation, the /proc/apm device will provide
2506 battery status information, and user-space programs will receive
2507 notification of APM "events" (e.g. battery status change).
2509 If you select "Y" here, you can disable actual use of the APM
2510 BIOS by passing the "apm=off" option to the kernel at boot time.
2512 Note that the APM support is almost completely disabled for
2513 machines with more than one CPU.
2515 In order to use APM, you will need supporting software. For location
2516 and more information, read <file:Documentation/power/apm-acpi.rst>
2517 and the Battery Powered Linux mini-HOWTO, available from
2518 <http://www.tldp.org/docs.html#howto>.
2520 This driver does not spin down disk drives (see the hdparm(8)
2521 manpage ("man 8 hdparm") for that), and it doesn't turn off
2522 VESA-compliant "green" monitors.
2524 This driver does not support the TI 4000M TravelMate and the ACER
2525 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2526 desktop machines also don't have compliant BIOSes, and this driver
2527 may cause those machines to panic during the boot phase.
2529 Generally, if you don't have a battery in your machine, there isn't
2530 much point in using this driver and you should say N. If you get
2531 random kernel OOPSes or reboots that don't seem to be related to
2532 anything, try disabling/enabling this option (or disabling/enabling
2535 Some other things you should try when experiencing seemingly random,
2538 1) make sure that you have enough swap space and that it is
2540 2) pass the "no-hlt" option to the kernel
2541 3) switch on floating point emulation in the kernel and pass
2542 the "no387" option to the kernel
2543 4) pass the "floppy=nodma" option to the kernel
2544 5) pass the "mem=4M" option to the kernel (thereby disabling
2545 all but the first 4 MB of RAM)
2546 6) make sure that the CPU is not over clocked.
2547 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2548 8) disable the cache from your BIOS settings
2549 9) install a fan for the video card or exchange video RAM
2550 10) install a better fan for the CPU
2551 11) exchange RAM chips
2552 12) exchange the motherboard.
2554 To compile this driver as a module, choose M here: the
2555 module will be called apm.
2559 config APM_IGNORE_USER_SUSPEND
2560 bool "Ignore USER SUSPEND"
2562 This option will ignore USER SUSPEND requests. On machines with a
2563 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2564 series notebooks, it is necessary to say Y because of a BIOS bug.
2566 config APM_DO_ENABLE
2567 bool "Enable PM at boot time"
2569 Enable APM features at boot time. From page 36 of the APM BIOS
2570 specification: "When disabled, the APM BIOS does not automatically
2571 power manage devices, enter the Standby State, enter the Suspend
2572 State, or take power saving steps in response to CPU Idle calls."
2573 This driver will make CPU Idle calls when Linux is idle (unless this
2574 feature is turned off -- see "Do CPU IDLE calls", below). This
2575 should always save battery power, but more complicated APM features
2576 will be dependent on your BIOS implementation. You may need to turn
2577 this option off if your computer hangs at boot time when using APM
2578 support, or if it beeps continuously instead of suspending. Turn
2579 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2580 T400CDT. This is off by default since most machines do fine without
2585 bool "Make CPU Idle calls when idle"
2587 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2588 On some machines, this can activate improved power savings, such as
2589 a slowed CPU clock rate, when the machine is idle. These idle calls
2590 are made after the idle loop has run for some length of time (e.g.,
2591 333 mS). On some machines, this will cause a hang at boot time or
2592 whenever the CPU becomes idle. (On machines with more than one CPU,
2593 this option does nothing.)
2595 config APM_DISPLAY_BLANK
2596 bool "Enable console blanking using APM"
2598 Enable console blanking using the APM. Some laptops can use this to
2599 turn off the LCD backlight when the screen blanker of the Linux
2600 virtual console blanks the screen. Note that this is only used by
2601 the virtual console screen blanker, and won't turn off the backlight
2602 when using the X Window system. This also doesn't have anything to
2603 do with your VESA-compliant power-saving monitor. Further, this
2604 option doesn't work for all laptops -- it might not turn off your
2605 backlight at all, or it might print a lot of errors to the console,
2606 especially if you are using gpm.
2608 config APM_ALLOW_INTS
2609 bool "Allow interrupts during APM BIOS calls"
2611 Normally we disable external interrupts while we are making calls to
2612 the APM BIOS as a measure to lessen the effects of a badly behaving
2613 BIOS implementation. The BIOS should reenable interrupts if it
2614 needs to. Unfortunately, some BIOSes do not -- especially those in
2615 many of the newer IBM Thinkpads. If you experience hangs when you
2616 suspend, try setting this to Y. Otherwise, say N.
2620 source "drivers/cpufreq/Kconfig"
2622 source "drivers/cpuidle/Kconfig"
2624 source "drivers/idle/Kconfig"
2629 menu "Bus options (PCI etc.)"
2632 prompt "PCI access mode"
2633 depends on X86_32 && PCI
2636 On PCI systems, the BIOS can be used to detect the PCI devices and
2637 determine their configuration. However, some old PCI motherboards
2638 have BIOS bugs and may crash if this is done. Also, some embedded
2639 PCI-based systems don't have any BIOS at all. Linux can also try to
2640 detect the PCI hardware directly without using the BIOS.
2642 With this option, you can specify how Linux should detect the
2643 PCI devices. If you choose "BIOS", the BIOS will be used,
2644 if you choose "Direct", the BIOS won't be used, and if you
2645 choose "MMConfig", then PCI Express MMCONFIG will be used.
2646 If you choose "Any", the kernel will try MMCONFIG, then the
2647 direct access method and falls back to the BIOS if that doesn't
2648 work. If unsure, go with the default, which is "Any".
2653 config PCI_GOMMCONFIG
2670 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2672 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2675 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2678 bool "Support mmconfig PCI config space access" if X86_64
2680 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2681 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2685 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2689 depends on PCI && XEN
2692 config MMCONF_FAM10H
2694 depends on X86_64 && PCI_MMCONFIG && ACPI
2696 config PCI_CNB20LE_QUIRK
2697 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2700 Read the PCI windows out of the CNB20LE host bridge. This allows
2701 PCI hotplug to work on systems with the CNB20LE chipset which do
2704 There's no public spec for this chipset, and this functionality
2705 is known to be incomplete.
2707 You should say N unless you know you need this.
2710 bool "ISA bus support on modern systems" if EXPERT
2712 Expose ISA bus device drivers and options available for selection and
2713 configuration. Enable this option if your target machine has an ISA
2714 bus. ISA is an older system, displaced by PCI and newer bus
2715 architectures -- if your target machine is modern, it probably does
2716 not have an ISA bus.
2720 # x86_64 have no ISA slots, but can have ISA-style DMA.
2722 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2725 Enables ISA-style DMA support for devices requiring such controllers.
2733 Find out whether you have ISA slots on your motherboard. ISA is the
2734 name of a bus system, i.e. the way the CPU talks to the other stuff
2735 inside your box. Other bus systems are PCI, EISA, MicroChannel
2736 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2737 newer boards don't support it. If you have ISA, say Y, otherwise N.
2740 tristate "NatSemi SCx200 support"
2742 This provides basic support for National Semiconductor's
2743 (now AMD's) Geode processors. The driver probes for the
2744 PCI-IDs of several on-chip devices, so its a good dependency
2745 for other scx200_* drivers.
2747 If compiled as a module, the driver is named scx200.
2749 config SCx200HR_TIMER
2750 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2754 This driver provides a clocksource built upon the on-chip
2755 27MHz high-resolution timer. Its also a workaround for
2756 NSC Geode SC-1100's buggy TSC, which loses time when the
2757 processor goes idle (as is done by the scheduler). The
2758 other workaround is idle=poll boot option.
2761 bool "One Laptop Per Child support"
2769 Add support for detecting the unique features of the OLPC
2773 bool "OLPC XO-1 Power Management"
2774 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2776 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2779 bool "OLPC XO-1 Real Time Clock"
2780 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2782 Add support for the XO-1 real time clock, which can be used as a
2783 programmable wakeup source.
2786 bool "OLPC XO-1 SCI extras"
2787 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2791 Add support for SCI-based features of the OLPC XO-1 laptop:
2792 - EC-driven system wakeups
2796 - AC adapter status updates
2797 - Battery status updates
2799 config OLPC_XO15_SCI
2800 bool "OLPC XO-1.5 SCI extras"
2801 depends on OLPC && ACPI
2804 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2805 - EC-driven system wakeups
2806 - AC adapter status updates
2807 - Battery status updates
2810 bool "PCEngines ALIX System Support (LED setup)"
2813 This option enables system support for the PCEngines ALIX.
2814 At present this just sets up LEDs for GPIO control on
2815 ALIX2/3/6 boards. However, other system specific setup should
2818 Note: You must still enable the drivers for GPIO and LED support
2819 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2821 Note: You have to set alix.force=1 for boards with Award BIOS.
2824 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2827 This option enables system support for the Soekris Engineering net5501.
2830 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2834 This option enables system support for the Traverse Technologies GEOS.
2837 bool "Technologic Systems TS-5500 platform support"
2839 select CHECK_SIGNATURE
2843 This option enables system support for the Technologic Systems TS-5500.
2849 depends on CPU_SUP_AMD && PCI
2852 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2854 Firmwares often provide initial graphics framebuffers so the BIOS,
2855 bootloader or kernel can show basic video-output during boot for
2856 user-guidance and debugging. Historically, x86 used the VESA BIOS
2857 Extensions and EFI-framebuffers for this, which are mostly limited
2859 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2860 framebuffers so the new generic system-framebuffer drivers can be
2861 used on x86. If the framebuffer is not compatible with the generic
2862 modes, it is advertised as fallback platform framebuffer so legacy
2863 drivers like efifb, vesafb and uvesafb can pick it up.
2864 If this option is not selected, all system framebuffers are always
2865 marked as fallback platform framebuffers as usual.
2867 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2868 not be able to pick up generic system framebuffers if this option
2869 is selected. You are highly encouraged to enable simplefb as
2870 replacement if you select this option. simplefb can correctly deal
2871 with generic system framebuffers. But you should still keep vesafb
2872 and others enabled as fallback if a system framebuffer is
2873 incompatible with simplefb.
2880 menu "Binary Emulations"
2882 config IA32_EMULATION
2883 bool "IA32 Emulation"
2885 select ARCH_WANT_OLD_COMPAT_IPC
2887 select COMPAT_BINFMT_ELF
2888 select COMPAT_OLD_SIGACTION
2890 Include code to run legacy 32-bit programs under a
2891 64-bit kernel. You should likely turn this on, unless you're
2892 100% sure that you don't have any 32-bit programs left.
2895 tristate "IA32 a.out support"
2896 depends on IA32_EMULATION
2899 Support old a.out binaries in the 32bit emulation.
2902 bool "x32 ABI for 64-bit mode"
2905 Include code to run binaries for the x32 native 32-bit ABI
2906 for 64-bit processors. An x32 process gets access to the
2907 full 64-bit register file and wide data path while leaving
2908 pointers at 32 bits for smaller memory footprint.
2910 You will need a recent binutils (2.22 or later) with
2911 elf32_x86_64 support enabled to compile a kernel with this
2916 depends on IA32_EMULATION || X86_32
2918 select OLD_SIGSUSPEND3
2922 depends on IA32_EMULATION || X86_X32
2925 config COMPAT_FOR_U64_ALIGNMENT
2928 config SYSVIPC_COMPAT
2936 config HAVE_ATOMIC_IOMAP
2940 config X86_DEV_DMA_OPS
2943 source "drivers/firmware/Kconfig"
2945 source "arch/x86/kvm/Kconfig"