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
34 config FORCE_DYNAMIC_FTRACE
37 depends on FUNCTION_TRACER
40 We keep the static function tracing (!DYNAMIC_FTRACE) around
41 in order to test the non static function tracing in the
42 generic code, as other architectures still use it. But we
43 only need to keep it around for x86_64. No need to keep it
44 for x86_32. For x86_32, force DYNAMIC_FTRACE.
48 # ( Note that options that are marked 'if X86_64' could in principle be
49 # ported to 32-bit as well. )
54 # Note: keep this list sorted alphabetically
56 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
57 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
58 select ARCH_32BIT_OFF_T if X86_32
59 select ARCH_CLOCKSOURCE_INIT
60 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
61 select ARCH_HAS_DEBUG_VIRTUAL
62 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
63 select ARCH_HAS_DEVMEM_IS_ALLOWED
64 select ARCH_HAS_EARLY_DEBUG if KGDB
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 && STACK_VALIDATION
71 select ARCH_HAS_MEM_ENCRYPT
72 select ARCH_HAS_MEMBARRIER_SYNC_CORE
73 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
74 select ARCH_HAS_PMEM_API if X86_64
75 select ARCH_HAS_PTE_DEVMAP if X86_64
76 select ARCH_HAS_PTE_SPECIAL
77 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
78 select ARCH_HAS_COPY_MC if X86_64
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_SYSCALL_WRAPPER
85 select ARCH_HAS_UBSAN_SANITIZE_ALL
86 select ARCH_HAS_DEBUG_WX
87 select ARCH_HAVE_NMI_SAFE_CMPXCHG
88 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
89 select ARCH_MIGHT_HAVE_PC_PARPORT
90 select ARCH_MIGHT_HAVE_PC_SERIO
92 select ARCH_SUPPORTS_ACPI
93 select ARCH_SUPPORTS_ATOMIC_RMW
94 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
95 select ARCH_USE_BUILTIN_BSWAP
96 select ARCH_USE_QUEUED_RWLOCKS
97 select ARCH_USE_QUEUED_SPINLOCKS
98 select ARCH_USE_SYM_ANNOTATIONS
99 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
100 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
101 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
102 select ARCH_WANT_HUGE_PMD_SHARE
103 select ARCH_WANTS_THP_SWAP if X86_64
104 select BUILDTIME_TABLE_SORT
106 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
107 select CLOCKSOURCE_WATCHDOG
108 select DCACHE_WORD_ACCESS
109 select EDAC_ATOMIC_SCRUB
111 select GENERIC_CLOCKEVENTS
112 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
113 select GENERIC_CLOCKEVENTS_MIN_ADJUST
114 select GENERIC_CMOS_UPDATE
115 select GENERIC_CPU_AUTOPROBE
116 select GENERIC_CPU_VULNERABILITIES
117 select GENERIC_EARLY_IOREMAP
119 select GENERIC_FIND_FIRST_BIT
121 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
122 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
123 select GENERIC_IRQ_MIGRATION if SMP
124 select GENERIC_IRQ_PROBE
125 select GENERIC_IRQ_RESERVATION_MODE
126 select GENERIC_IRQ_SHOW
127 select GENERIC_PENDING_IRQ if SMP
128 select GENERIC_PTDUMP
129 select GENERIC_SMP_IDLE_THREAD
130 select GENERIC_STRNCPY_FROM_USER
131 select GENERIC_STRNLEN_USER
132 select GENERIC_TIME_VSYSCALL
133 select GENERIC_GETTIMEOFDAY
134 select GENERIC_VDSO_TIME_NS
135 select GUP_GET_PTE_LOW_HIGH if X86_PAE
136 select HARDIRQS_SW_RESEND
137 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
138 select HAVE_ACPI_APEI if ACPI
139 select HAVE_ACPI_APEI_NMI if ACPI
140 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
141 select HAVE_ARCH_AUDITSYSCALL
142 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
143 select HAVE_ARCH_JUMP_LABEL
144 select HAVE_ARCH_JUMP_LABEL_RELATIVE
145 select HAVE_ARCH_KASAN if X86_64
146 select HAVE_ARCH_KASAN_VMALLOC if X86_64
147 select HAVE_ARCH_KGDB
148 select HAVE_ARCH_MMAP_RND_BITS if MMU
149 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
150 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
151 select HAVE_ARCH_PREL32_RELOCATIONS
152 select HAVE_ARCH_SECCOMP_FILTER
153 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
154 select HAVE_ARCH_STACKLEAK
155 select HAVE_ARCH_TRACEHOOK
156 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
157 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
158 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
159 select HAVE_ARCH_VMAP_STACK if X86_64
160 select HAVE_ARCH_WITHIN_STACK_FRAMES
161 select HAVE_ASM_MODVERSIONS
162 select HAVE_CMPXCHG_DOUBLE
163 select HAVE_CMPXCHG_LOCAL
164 select HAVE_CONTEXT_TRACKING if X86_64
165 select HAVE_C_RECORDMCOUNT
166 select HAVE_DEBUG_KMEMLEAK
167 select HAVE_DMA_CONTIGUOUS
168 select HAVE_DYNAMIC_FTRACE
169 select HAVE_DYNAMIC_FTRACE_WITH_REGS
170 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
172 select HAVE_EFFICIENT_UNALIGNED_ACCESS
174 select HAVE_EXIT_THREAD
176 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
177 select HAVE_FTRACE_MCOUNT_RECORD
178 select HAVE_FUNCTION_GRAPH_TRACER
179 select HAVE_FUNCTION_TRACER
180 select HAVE_GCC_PLUGINS
181 select HAVE_HW_BREAKPOINT
183 select HAVE_IOREMAP_PROT
184 select HAVE_IRQ_TIME_ACCOUNTING
185 select HAVE_KERNEL_BZIP2
186 select HAVE_KERNEL_GZIP
187 select HAVE_KERNEL_LZ4
188 select HAVE_KERNEL_LZMA
189 select HAVE_KERNEL_LZO
190 select HAVE_KERNEL_XZ
191 select HAVE_KERNEL_ZSTD
193 select HAVE_KPROBES_ON_FTRACE
194 select HAVE_FUNCTION_ERROR_INJECTION
195 select HAVE_KRETPROBES
197 select HAVE_LIVEPATCH if X86_64
198 select HAVE_MIXED_BREAKPOINTS_REGS
199 select HAVE_MOD_ARCH_SPECIFIC
203 select HAVE_OPTPROBES
204 select HAVE_PCSPKR_PLATFORM
205 select HAVE_PERF_EVENTS
206 select HAVE_PERF_EVENTS_NMI
207 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
209 select HAVE_PERF_REGS
210 select HAVE_PERF_USER_STACK_DUMP
211 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
212 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
213 select HAVE_REGS_AND_STACK_ACCESS_API
214 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
215 select HAVE_FUNCTION_ARG_ACCESS_API
216 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
217 select HAVE_STACK_VALIDATION if X86_64
218 select HAVE_STATIC_CALL
219 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
221 select HAVE_SYSCALL_TRACEPOINTS
222 select HAVE_UNSTABLE_SCHED_CLOCK
223 select HAVE_USER_RETURN_NOTIFIER
224 select HAVE_GENERIC_VDSO
225 select HOTPLUG_SMT if SMP
226 select IRQ_FORCED_THREADING
227 select NEED_SG_DMA_LENGTH
228 select PCI_DOMAINS if PCI
229 select PCI_LOCKLESS_CONFIG if PCI
232 select RTC_MC146818_LIB
235 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
236 select SYSCTL_EXCEPTION_TRACE
237 select THREAD_INFO_IN_TASK
238 select USER_STACKTRACE_SUPPORT
240 select HAVE_ARCH_KCSAN if X86_64
241 select X86_FEATURE_NAMES if PROC_FS
242 select PROC_PID_ARCH_STATUS if PROC_FS
243 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
245 config INSTRUCTION_DECODER
247 depends on KPROBES || PERF_EVENTS || UPROBES
251 default "elf32-i386" if X86_32
252 default "elf64-x86-64" if X86_64
254 config LOCKDEP_SUPPORT
257 config STACKTRACE_SUPPORT
263 config ARCH_MMAP_RND_BITS_MIN
267 config ARCH_MMAP_RND_BITS_MAX
271 config ARCH_MMAP_RND_COMPAT_BITS_MIN
274 config ARCH_MMAP_RND_COMPAT_BITS_MAX
280 config GENERIC_ISA_DMA
282 depends on ISA_DMA_API
287 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
289 config GENERIC_BUG_RELATIVE_POINTERS
292 config ARCH_MAY_HAVE_PC_FDC
294 depends on ISA_DMA_API
296 config GENERIC_CALIBRATE_DELAY
299 config ARCH_HAS_CPU_RELAX
302 config ARCH_HAS_CACHE_LINE_SIZE
305 config ARCH_HAS_FILTER_PGPROT
308 config HAVE_SETUP_PER_CPU_AREA
311 config NEED_PER_CPU_EMBED_FIRST_CHUNK
314 config NEED_PER_CPU_PAGE_FIRST_CHUNK
317 config ARCH_HIBERNATION_POSSIBLE
320 config ARCH_SUSPEND_POSSIBLE
323 config ARCH_WANT_GENERAL_HUGETLB
332 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
335 config KASAN_SHADOW_OFFSET
338 default 0xdffffc0000000000
340 config HAVE_INTEL_TXT
342 depends on INTEL_IOMMU && ACPI
346 depends on X86_32 && SMP
350 depends on X86_64 && SMP
352 config X86_32_LAZY_GS
354 depends on X86_32 && !STACKPROTECTOR
356 config ARCH_SUPPORTS_UPROBES
359 config FIX_EARLYCON_MEM
362 config DYNAMIC_PHYSICAL_MASK
365 config PGTABLE_LEVELS
367 default 5 if X86_5LEVEL
372 config CC_HAS_SANE_STACKPROTECTOR
374 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
375 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
377 We have to make sure stack protector is unconditionally disabled if
378 the compiler produces broken code.
380 menu "Processor type and features"
383 bool "DMA memory allocation support" if EXPERT
386 DMA memory allocation support allows devices with less than 32-bit
387 addressing to allocate within the first 16MB of address space.
388 Disable if no such devices will be used.
393 bool "Symmetric multi-processing support"
395 This enables support for systems with more than one CPU. If you have
396 a system with only one CPU, say N. If you have a system with more
399 If you say N here, the kernel will run on uni- and multiprocessor
400 machines, but will use only one CPU of a multiprocessor machine. If
401 you say Y here, the kernel will run on many, but not all,
402 uniprocessor machines. On a uniprocessor machine, the kernel
403 will run faster if you say N here.
405 Note that if you say Y here and choose architecture "586" or
406 "Pentium" under "Processor family", the kernel will not work on 486
407 architectures. Similarly, multiprocessor kernels for the "PPro"
408 architecture may not work on all Pentium based boards.
410 People using multiprocessor machines who say Y here should also say
411 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
412 Management" code will be disabled if you say Y here.
414 See also <file:Documentation/x86/i386/IO-APIC.rst>,
415 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
416 <http://www.tldp.org/docs.html#howto>.
418 If you don't know what to do here, say N.
420 config X86_FEATURE_NAMES
421 bool "Processor feature human-readable names" if EMBEDDED
424 This option compiles in a table of x86 feature bits and corresponding
425 names. This is required to support /proc/cpuinfo and a few kernel
426 messages. You can disable this to save space, at the expense of
427 making those few kernel messages show numeric feature bits instead.
432 bool "Support x2apic"
433 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
435 This enables x2apic support on CPUs that have this feature.
437 This allows 32-bit apic IDs (so it can support very large systems),
438 and accesses the local apic via MSRs not via mmio.
440 If you don't know what to do here, say N.
443 bool "Enable MPS table" if ACPI || SFI
445 depends on X86_LOCAL_APIC
447 For old smp systems that do not have proper acpi support. Newer systems
448 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
452 depends on X86_GOLDFISH
455 bool "Avoid speculative indirect branches in kernel"
458 Compile kernel with the retpoline compiler options to guard against
459 kernel-to-user data leaks by avoiding speculative indirect
460 branches. Requires a compiler with -mindirect-branch=thunk-extern
461 support for full protection. The kernel may run slower.
463 config X86_CPU_RESCTRL
464 bool "x86 CPU resource control support"
465 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
467 select PROC_CPU_RESCTRL if PROC_FS
469 Enable x86 CPU resource control support.
471 Provide support for the allocation and monitoring of system resources
474 Intel calls this Intel Resource Director Technology
475 (Intel(R) RDT). More information about RDT can be found in the
476 Intel x86 Architecture Software Developer Manual.
478 AMD calls this AMD Platform Quality of Service (AMD QoS).
479 More information about AMD QoS can be found in the AMD64 Technology
480 Platform Quality of Service Extensions manual.
486 bool "Support for big SMP systems with more than 8 CPUs"
489 This option is needed for the systems that have more than 8 CPUs.
491 config X86_EXTENDED_PLATFORM
492 bool "Support for extended (non-PC) x86 platforms"
495 If you disable this option then the kernel will only support
496 standard PC platforms. (which covers the vast majority of
499 If you enable this option then you'll be able to select support
500 for the following (non-PC) 32 bit x86 platforms:
501 Goldfish (Android emulator)
504 SGI 320/540 (Visual Workstation)
505 STA2X11-based (e.g. Northville)
506 Moorestown MID devices
508 If you have one of these systems, or if you want to build a
509 generic distribution kernel, say Y here - otherwise say N.
513 config X86_EXTENDED_PLATFORM
514 bool "Support for extended (non-PC) x86 platforms"
517 If you disable this option then the kernel will only support
518 standard PC platforms. (which covers the vast majority of
521 If you enable this option then you'll be able to select support
522 for the following (non-PC) 64 bit x86 platforms:
527 If you have one of these systems, or if you want to build a
528 generic distribution kernel, say Y here - otherwise say N.
530 # This is an alphabetically sorted list of 64 bit extended platforms
531 # Please maintain the alphabetic order if and when there are additions
533 bool "Numascale NumaChip"
535 depends on X86_EXTENDED_PLATFORM
538 depends on X86_X2APIC
539 depends on PCI_MMCONFIG
541 Adds support for Numascale NumaChip large-SMP systems. Needed to
542 enable more than ~168 cores.
543 If you don't have one of these, you should say N here.
547 select HYPERVISOR_GUEST
549 depends on X86_64 && PCI
550 depends on X86_EXTENDED_PLATFORM
553 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
554 supposed to run on these EM64T-based machines. Only choose this option
555 if you have one of these machines.
558 bool "SGI Ultraviolet"
560 depends on X86_EXTENDED_PLATFORM
563 depends on X86_X2APIC
566 This option is needed in order to support SGI Ultraviolet systems.
567 If you don't have one of these, you should say N here.
569 # Following is an alphabetically sorted list of 32 bit extended platforms
570 # Please maintain the alphabetic order if and when there are additions
573 bool "Goldfish (Virtual Platform)"
574 depends on X86_EXTENDED_PLATFORM
576 Enable support for the Goldfish virtual platform used primarily
577 for Android development. Unless you are building for the Android
578 Goldfish emulator say N here.
581 bool "CE4100 TV platform"
583 depends on PCI_GODIRECT
584 depends on X86_IO_APIC
586 depends on X86_EXTENDED_PLATFORM
587 select X86_REBOOTFIXUPS
589 select OF_EARLY_FLATTREE
591 Select for the Intel CE media processor (CE4100) SOC.
592 This option compiles in support for the CE4100 SOC for settop
593 boxes and media devices.
596 bool "Intel MID platform support"
597 depends on X86_EXTENDED_PLATFORM
598 depends on X86_PLATFORM_DEVICES
600 depends on X86_64 || (PCI_GOANY && X86_32)
601 depends on X86_IO_APIC
607 select MFD_INTEL_MSIC
609 Select to build a kernel capable of supporting Intel MID (Mobile
610 Internet Device) platform systems which do not have the PCI legacy
611 interfaces. If you are building for a PC class system say N here.
613 Intel MID platforms are based on an Intel processor and chipset which
614 consume less power than most of the x86 derivatives.
616 config X86_INTEL_QUARK
617 bool "Intel Quark platform support"
619 depends on X86_EXTENDED_PLATFORM
620 depends on X86_PLATFORM_DEVICES
624 depends on X86_IO_APIC
629 Select to include support for Quark X1000 SoC.
630 Say Y here if you have a Quark based system such as the Arduino
631 compatible Intel Galileo.
633 config X86_INTEL_LPSS
634 bool "Intel Low Power Subsystem Support"
635 depends on X86 && ACPI && PCI
640 Select to build support for Intel Low Power Subsystem such as
641 found on Intel Lynxpoint PCH. Selecting this option enables
642 things like clock tree (common clock framework) and pincontrol
643 which are needed by the LPSS peripheral drivers.
645 config X86_AMD_PLATFORM_DEVICE
646 bool "AMD ACPI2Platform devices support"
651 Select to interpret AMD specific ACPI device to platform device
652 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
653 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
654 implemented under PINCTRL subsystem.
657 tristate "Intel SoC IOSF Sideband support for SoC platforms"
660 This option enables sideband register access support for Intel SoC
661 platforms. On these platforms the IOSF sideband is used in lieu of
662 MSR's for some register accesses, mostly but not limited to thermal
663 and power. Drivers may query the availability of this device to
664 determine if they need the sideband in order to work on these
665 platforms. The sideband is available on the following SoC products.
666 This list is not meant to be exclusive.
671 You should say Y if you are running a kernel on one of these SoC's.
673 config IOSF_MBI_DEBUG
674 bool "Enable IOSF sideband access through debugfs"
675 depends on IOSF_MBI && DEBUG_FS
677 Select this option to expose the IOSF sideband access registers (MCR,
678 MDR, MCRX) through debugfs to write and read register information from
679 different units on the SoC. This is most useful for obtaining device
680 state information for debug and analysis. As this is a general access
681 mechanism, users of this option would have specific knowledge of the
682 device they want to access.
684 If you don't require the option or are in doubt, say N.
687 bool "RDC R-321x SoC"
689 depends on X86_EXTENDED_PLATFORM
691 select X86_REBOOTFIXUPS
693 This option is needed for RDC R-321x system-on-chip, also known
695 If you don't have one of these chips, you should say N here.
697 config X86_32_NON_STANDARD
698 bool "Support non-standard 32-bit SMP architectures"
699 depends on X86_32 && SMP
700 depends on X86_EXTENDED_PLATFORM
702 This option compiles in the bigsmp and STA2X11 default
703 subarchitectures. It is intended for a generic binary
704 kernel. If you select them all, kernel will probe it one by
705 one and will fallback to default.
707 # Alphabetically sorted list of Non standard 32 bit platforms
709 config X86_SUPPORTS_MEMORY_FAILURE
711 # MCE code calls memory_failure():
713 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
714 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
715 depends on X86_64 || !SPARSEMEM
716 select ARCH_SUPPORTS_MEMORY_FAILURE
719 bool "STA2X11 Companion Chip Support"
720 depends on X86_32_NON_STANDARD && PCI
725 This adds support for boards based on the STA2X11 IO-Hub,
726 a.k.a. "ConneXt". The chip is used in place of the standard
727 PC chipset, so all "standard" peripherals are missing. If this
728 option is selected the kernel will still be able to boot on
729 standard PC machines.
732 tristate "Eurobraille/Iris poweroff module"
735 The Iris machines from EuroBraille do not have APM or ACPI support
736 to shut themselves down properly. A special I/O sequence is
737 needed to do so, which is what this module does at
740 This is only for Iris machines from EuroBraille.
744 config SCHED_OMIT_FRAME_POINTER
746 prompt "Single-depth WCHAN output"
749 Calculate simpler /proc/<PID>/wchan values. If this option
750 is disabled then wchan values will recurse back to the
751 caller function. This provides more accurate wchan values,
752 at the expense of slightly more scheduling overhead.
754 If in doubt, say "Y".
756 menuconfig HYPERVISOR_GUEST
757 bool "Linux guest support"
759 Say Y here to enable options for running Linux under various hyper-
760 visors. This option enables basic hypervisor detection and platform
763 If you say N, all options in this submenu will be skipped and
764 disabled, and Linux guest support won't be built in.
769 bool "Enable paravirtualization code"
771 This changes the kernel so it can modify itself when it is run
772 under a hypervisor, potentially improving performance significantly
773 over full virtualization. However, when run without a hypervisor
774 the kernel is theoretically slower and slightly larger.
779 config PARAVIRT_DEBUG
780 bool "paravirt-ops debugging"
781 depends on PARAVIRT && DEBUG_KERNEL
783 Enable to debug paravirt_ops internals. Specifically, BUG if
784 a paravirt_op is missing when it is called.
786 config PARAVIRT_SPINLOCKS
787 bool "Paravirtualization layer for spinlocks"
788 depends on PARAVIRT && SMP
790 Paravirtualized spinlocks allow a pvops backend to replace the
791 spinlock implementation with something virtualization-friendly
792 (for example, block the virtual CPU rather than spinning).
794 It has a minimal impact on native kernels and gives a nice performance
795 benefit on paravirtualized KVM / Xen kernels.
797 If you are unsure how to answer this question, answer Y.
799 config X86_HV_CALLBACK_VECTOR
802 source "arch/x86/xen/Kconfig"
805 bool "KVM Guest support (including kvmclock)"
807 select PARAVIRT_CLOCK
808 select ARCH_CPUIDLE_HALTPOLL
809 select X86_HV_CALLBACK_VECTOR
812 This option enables various optimizations for running under the KVM
813 hypervisor. It includes a paravirtualized clock, so that instead
814 of relying on a PIT (or probably other) emulation by the
815 underlying device model, the host provides the guest with
816 timing infrastructure such as time of day, and system time
818 config ARCH_CPUIDLE_HALTPOLL
820 prompt "Disable host haltpoll when loading haltpoll driver"
822 If virtualized under KVM, disable host haltpoll.
825 bool "Support for running PVH guests"
827 This option enables the PVH entry point for guest virtual machines
828 as specified in the x86/HVM direct boot ABI.
830 config PARAVIRT_TIME_ACCOUNTING
831 bool "Paravirtual steal time accounting"
834 Select this option to enable fine granularity task steal time
835 accounting. Time spent executing other tasks in parallel with
836 the current vCPU is discounted from the vCPU power. To account for
837 that, there can be a small performance impact.
839 If in doubt, say N here.
841 config PARAVIRT_CLOCK
844 config JAILHOUSE_GUEST
845 bool "Jailhouse non-root cell support"
846 depends on X86_64 && PCI
849 This option allows to run Linux as guest in a Jailhouse non-root
850 cell. You can leave this option disabled if you only want to start
851 Jailhouse and run Linux afterwards in the root cell.
854 bool "ACRN Guest support"
856 select X86_HV_CALLBACK_VECTOR
858 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
859 a flexible, lightweight reference open-source hypervisor, built with
860 real-time and safety-criticality in mind. It is built for embedded
861 IOT with small footprint and real-time features. More details can be
862 found in https://projectacrn.org/.
864 endif #HYPERVISOR_GUEST
866 source "arch/x86/Kconfig.cpu"
870 prompt "HPET Timer Support" if X86_32
872 Use the IA-PC HPET (High Precision Event Timer) to manage
873 time in preference to the PIT and RTC, if a HPET is
875 HPET is the next generation timer replacing legacy 8254s.
876 The HPET provides a stable time base on SMP
877 systems, unlike the TSC, but it is more expensive to access,
878 as it is off-chip. The interface used is documented
879 in the HPET spec, revision 1.
881 You can safely choose Y here. However, HPET will only be
882 activated if the platform and the BIOS support this feature.
883 Otherwise the 8254 will be used for timing services.
885 Choose N to continue using the legacy 8254 timer.
887 config HPET_EMULATE_RTC
889 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
892 def_bool y if X86_INTEL_MID
893 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
895 depends on X86_INTEL_MID && SFI
897 APB timer is the replacement for 8254, HPET on X86 MID platforms.
898 The APBT provides a stable time base on SMP
899 systems, unlike the TSC, but it is more expensive to access,
900 as it is off-chip. APB timers are always running regardless of CPU
901 C states, they are used as per CPU clockevent device when possible.
903 # Mark as expert because too many people got it wrong.
904 # The code disables itself when not needed.
907 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
908 bool "Enable DMI scanning" if EXPERT
910 Enabled scanning of DMI to identify machine quirks. Say Y
911 here unless you have verified that your setup is not
912 affected by entries in the DMI blacklist. Required by PNP
916 bool "Old AMD GART IOMMU support"
920 depends on X86_64 && PCI && AMD_NB
922 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
923 GART based hardware IOMMUs.
925 The GART supports full DMA access for devices with 32-bit access
926 limitations, on systems with more than 3 GB. This is usually needed
927 for USB, sound, many IDE/SATA chipsets and some other devices.
929 Newer systems typically have a modern AMD IOMMU, supported via
930 the CONFIG_AMD_IOMMU=y config option.
932 In normal configurations this driver is only active when needed:
933 there's more than 3 GB of memory and the system contains a
934 32-bit limited device.
939 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
940 depends on X86_64 && SMP && DEBUG_KERNEL
941 select CPUMASK_OFFSTACK
943 Enable maximum number of CPUS and NUMA Nodes for this architecture.
947 # The maximum number of CPUs supported:
949 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
950 # and which can be configured interactively in the
951 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
953 # The ranges are different on 32-bit and 64-bit kernels, depending on
954 # hardware capabilities and scalability features of the kernel.
956 # ( If MAXSMP is enabled we just use the highest possible value and disable
957 # interactive configuration. )
960 config NR_CPUS_RANGE_BEGIN
962 default NR_CPUS_RANGE_END if MAXSMP
966 config NR_CPUS_RANGE_END
969 default 64 if SMP && X86_BIGSMP
970 default 8 if SMP && !X86_BIGSMP
973 config NR_CPUS_RANGE_END
976 default 8192 if SMP && CPUMASK_OFFSTACK
977 default 512 if SMP && !CPUMASK_OFFSTACK
980 config NR_CPUS_DEFAULT
983 default 32 if X86_BIGSMP
987 config NR_CPUS_DEFAULT
990 default 8192 if MAXSMP
995 int "Maximum number of CPUs" if SMP && !MAXSMP
996 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
997 default NR_CPUS_DEFAULT
999 This allows you to specify the maximum number of CPUs which this
1000 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1001 supported value is 8192, otherwise the maximum value is 512. The
1002 minimum value which makes sense is 2.
1004 This is purely to save memory: each supported CPU adds about 8KB
1005 to the kernel image.
1012 prompt "Multi-core scheduler support"
1015 Multi-core scheduler support improves the CPU scheduler's decision
1016 making when dealing with multi-core CPU chips at a cost of slightly
1017 increased overhead in some places. If unsure say N here.
1019 config SCHED_MC_PRIO
1020 bool "CPU core priorities scheduler support"
1021 depends on SCHED_MC && CPU_SUP_INTEL
1022 select X86_INTEL_PSTATE
1026 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1027 core ordering determined at manufacturing time, which allows
1028 certain cores to reach higher turbo frequencies (when running
1029 single threaded workloads) than others.
1031 Enabling this kernel feature teaches the scheduler about
1032 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1033 scheduler's CPU selection logic accordingly, so that higher
1034 overall system performance can be achieved.
1036 This feature will have no effect on CPUs without this feature.
1038 If unsure say Y here.
1042 depends on !SMP && X86_LOCAL_APIC
1045 bool "Local APIC support on uniprocessors" if !PCI_MSI
1047 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1049 A local APIC (Advanced Programmable Interrupt Controller) is an
1050 integrated interrupt controller in the CPU. If you have a single-CPU
1051 system which has a processor with a local APIC, you can say Y here to
1052 enable and use it. If you say Y here even though your machine doesn't
1053 have a local APIC, then the kernel will still run with no slowdown at
1054 all. The local APIC supports CPU-generated self-interrupts (timer,
1055 performance counters), and the NMI watchdog which detects hard
1058 config X86_UP_IOAPIC
1059 bool "IO-APIC support on uniprocessors"
1060 depends on X86_UP_APIC
1062 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1063 SMP-capable replacement for PC-style interrupt controllers. Most
1064 SMP systems and many recent uniprocessor systems have one.
1066 If you have a single-CPU system with an IO-APIC, you can say Y here
1067 to use it. If you say Y here even though your machine doesn't have
1068 an IO-APIC, then the kernel will still run with no slowdown at all.
1070 config X86_LOCAL_APIC
1072 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1073 select IRQ_DOMAIN_HIERARCHY
1074 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1078 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1080 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1081 bool "Reroute for broken boot IRQs"
1082 depends on X86_IO_APIC
1084 This option enables a workaround that fixes a source of
1085 spurious interrupts. This is recommended when threaded
1086 interrupt handling is used on systems where the generation of
1087 superfluous "boot interrupts" cannot be disabled.
1089 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1090 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1091 kernel does during interrupt handling). On chipsets where this
1092 boot IRQ generation cannot be disabled, this workaround keeps
1093 the original IRQ line masked so that only the equivalent "boot
1094 IRQ" is delivered to the CPUs. The workaround also tells the
1095 kernel to set up the IRQ handler on the boot IRQ line. In this
1096 way only one interrupt is delivered to the kernel. Otherwise
1097 the spurious second interrupt may cause the kernel to bring
1098 down (vital) interrupt lines.
1100 Only affects "broken" chipsets. Interrupt sharing may be
1101 increased on these systems.
1104 bool "Machine Check / overheating reporting"
1105 select GENERIC_ALLOCATOR
1108 Machine Check support allows the processor to notify the
1109 kernel if it detects a problem (e.g. overheating, data corruption).
1110 The action the kernel takes depends on the severity of the problem,
1111 ranging from warning messages to halting the machine.
1113 config X86_MCELOG_LEGACY
1114 bool "Support for deprecated /dev/mcelog character device"
1117 Enable support for /dev/mcelog which is needed by the old mcelog
1118 userspace logging daemon. Consider switching to the new generation
1121 config X86_MCE_INTEL
1123 prompt "Intel MCE features"
1124 depends on X86_MCE && X86_LOCAL_APIC
1126 Additional support for intel specific MCE features such as
1127 the thermal monitor.
1131 prompt "AMD MCE features"
1132 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1134 Additional support for AMD specific MCE features such as
1135 the DRAM Error Threshold.
1137 config X86_ANCIENT_MCE
1138 bool "Support for old Pentium 5 / WinChip machine checks"
1139 depends on X86_32 && X86_MCE
1141 Include support for machine check handling on old Pentium 5 or WinChip
1142 systems. These typically need to be enabled explicitly on the command
1145 config X86_MCE_THRESHOLD
1146 depends on X86_MCE_AMD || X86_MCE_INTEL
1149 config X86_MCE_INJECT
1150 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1151 tristate "Machine check injector support"
1153 Provide support for injecting machine checks for testing purposes.
1154 If you don't know what a machine check is and you don't do kernel
1155 QA it is safe to say n.
1157 config X86_THERMAL_VECTOR
1159 depends on X86_MCE_INTEL
1161 source "arch/x86/events/Kconfig"
1163 config X86_LEGACY_VM86
1164 bool "Legacy VM86 support"
1167 This option allows user programs to put the CPU into V8086
1168 mode, which is an 80286-era approximation of 16-bit real mode.
1170 Some very old versions of X and/or vbetool require this option
1171 for user mode setting. Similarly, DOSEMU will use it if
1172 available to accelerate real mode DOS programs. However, any
1173 recent version of DOSEMU, X, or vbetool should be fully
1174 functional even without kernel VM86 support, as they will all
1175 fall back to software emulation. Nevertheless, if you are using
1176 a 16-bit DOS program where 16-bit performance matters, vm86
1177 mode might be faster than emulation and you might want to
1180 Note that any app that works on a 64-bit kernel is unlikely to
1181 need this option, as 64-bit kernels don't, and can't, support
1182 V8086 mode. This option is also unrelated to 16-bit protected
1183 mode and is not needed to run most 16-bit programs under Wine.
1185 Enabling this option increases the complexity of the kernel
1186 and slows down exception handling a tiny bit.
1188 If unsure, say N here.
1192 default X86_LEGACY_VM86
1195 bool "Enable support for 16-bit segments" if EXPERT
1197 depends on MODIFY_LDT_SYSCALL
1199 This option is required by programs like Wine to run 16-bit
1200 protected mode legacy code on x86 processors. Disabling
1201 this option saves about 300 bytes on i386, or around 6K text
1202 plus 16K runtime memory on x86-64,
1206 depends on X86_16BIT && X86_32
1210 depends on X86_16BIT && X86_64
1212 config X86_VSYSCALL_EMULATION
1213 bool "Enable vsyscall emulation" if EXPERT
1217 This enables emulation of the legacy vsyscall page. Disabling
1218 it is roughly equivalent to booting with vsyscall=none, except
1219 that it will also disable the helpful warning if a program
1220 tries to use a vsyscall. With this option set to N, offending
1221 programs will just segfault, citing addresses of the form
1224 This option is required by many programs built before 2013, and
1225 care should be used even with newer programs if set to N.
1227 Disabling this option saves about 7K of kernel size and
1228 possibly 4K of additional runtime pagetable memory.
1230 config X86_IOPL_IOPERM
1231 bool "IOPERM and IOPL Emulation"
1234 This enables the ioperm() and iopl() syscalls which are necessary
1235 for legacy applications.
1237 Legacy IOPL support is an overbroad mechanism which allows user
1238 space aside of accessing all 65536 I/O ports also to disable
1239 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1240 capabilities and permission from potentially active security
1243 The emulation restricts the functionality of the syscall to
1244 only allowing the full range I/O port access, but prevents the
1245 ability to disable interrupts from user space which would be
1246 granted if the hardware IOPL mechanism would be used.
1249 tristate "Toshiba Laptop support"
1252 This adds a driver to safely access the System Management Mode of
1253 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1254 not work on models with a Phoenix BIOS. The System Management Mode
1255 is used to set the BIOS and power saving options on Toshiba portables.
1257 For information on utilities to make use of this driver see the
1258 Toshiba Linux utilities web site at:
1259 <http://www.buzzard.org.uk/toshiba/>.
1261 Say Y if you intend to run this kernel on a Toshiba portable.
1265 tristate "Dell i8k legacy laptop support"
1267 select SENSORS_DELL_SMM
1269 This option enables legacy /proc/i8k userspace interface in hwmon
1270 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1271 temperature and allows controlling fan speeds of Dell laptops via
1272 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1273 it reports also power and hotkey status. For fan speed control is
1274 needed userspace package i8kutils.
1276 Say Y if you intend to run this kernel on old Dell laptops or want to
1277 use userspace package i8kutils.
1280 config X86_REBOOTFIXUPS
1281 bool "Enable X86 board specific fixups for reboot"
1284 This enables chipset and/or board specific fixups to be done
1285 in order to get reboot to work correctly. This is only needed on
1286 some combinations of hardware and BIOS. The symptom, for which
1287 this config is intended, is when reboot ends with a stalled/hung
1290 Currently, the only fixup is for the Geode machines using
1291 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1293 Say Y if you want to enable the fixup. Currently, it's safe to
1294 enable this option even if you don't need it.
1298 bool "CPU microcode loading support"
1300 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1302 If you say Y here, you will be able to update the microcode on
1303 Intel and AMD processors. The Intel support is for the IA32 family,
1304 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1305 AMD support is for families 0x10 and later. You will obviously need
1306 the actual microcode binary data itself which is not shipped with
1309 The preferred method to load microcode from a detached initrd is described
1310 in Documentation/x86/microcode.rst. For that you need to enable
1311 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1312 initrd for microcode blobs.
1314 In addition, you can build the microcode into the kernel. For that you
1315 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1318 config MICROCODE_INTEL
1319 bool "Intel microcode loading support"
1320 depends on MICROCODE
1323 This options enables microcode patch loading support for Intel
1326 For the current Intel microcode data package go to
1327 <https://downloadcenter.intel.com> and search for
1328 'Linux Processor Microcode Data File'.
1330 config MICROCODE_AMD
1331 bool "AMD microcode loading support"
1332 depends on MICROCODE
1334 If you select this option, microcode patch loading support for AMD
1335 processors will be enabled.
1337 config MICROCODE_OLD_INTERFACE
1338 bool "Ancient loading interface (DEPRECATED)"
1340 depends on MICROCODE
1342 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1343 which was used by userspace tools like iucode_tool and microcode.ctl.
1344 It is inadequate because it runs too late to be able to properly
1345 load microcode on a machine and it needs special tools. Instead, you
1346 should've switched to the early loading method with the initrd or
1347 builtin microcode by now: Documentation/x86/microcode.rst
1350 tristate "/dev/cpu/*/msr - Model-specific register support"
1352 This device gives privileged processes access to the x86
1353 Model-Specific Registers (MSRs). It is a character device with
1354 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1355 MSR accesses are directed to a specific CPU on multi-processor
1359 tristate "/dev/cpu/*/cpuid - CPU information support"
1361 This device gives processes access to the x86 CPUID instruction to
1362 be executed on a specific processor. It is a character device
1363 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1367 prompt "High Memory Support"
1374 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1375 However, the address space of 32-bit x86 processors is only 4
1376 Gigabytes large. That means that, if you have a large amount of
1377 physical memory, not all of it can be "permanently mapped" by the
1378 kernel. The physical memory that's not permanently mapped is called
1381 If you are compiling a kernel which will never run on a machine with
1382 more than 1 Gigabyte total physical RAM, answer "off" here (default
1383 choice and suitable for most users). This will result in a "3GB/1GB"
1384 split: 3GB are mapped so that each process sees a 3GB virtual memory
1385 space and the remaining part of the 4GB virtual memory space is used
1386 by the kernel to permanently map as much physical memory as
1389 If the machine has between 1 and 4 Gigabytes physical RAM, then
1392 If more than 4 Gigabytes is used then answer "64GB" here. This
1393 selection turns Intel PAE (Physical Address Extension) mode on.
1394 PAE implements 3-level paging on IA32 processors. PAE is fully
1395 supported by Linux, PAE mode is implemented on all recent Intel
1396 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1397 then the kernel will not boot on CPUs that don't support PAE!
1399 The actual amount of total physical memory will either be
1400 auto detected or can be forced by using a kernel command line option
1401 such as "mem=256M". (Try "man bootparam" or see the documentation of
1402 your boot loader (lilo or loadlin) about how to pass options to the
1403 kernel at boot time.)
1405 If unsure, say "off".
1410 Select this if you have a 32-bit processor and between 1 and 4
1411 gigabytes of physical RAM.
1415 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1418 Select this if you have a 32-bit processor and more than 4
1419 gigabytes of physical RAM.
1424 prompt "Memory split" if EXPERT
1428 Select the desired split between kernel and user memory.
1430 If the address range available to the kernel is less than the
1431 physical memory installed, the remaining memory will be available
1432 as "high memory". Accessing high memory is a little more costly
1433 than low memory, as it needs to be mapped into the kernel first.
1434 Note that increasing the kernel address space limits the range
1435 available to user programs, making the address space there
1436 tighter. Selecting anything other than the default 3G/1G split
1437 will also likely make your kernel incompatible with binary-only
1440 If you are not absolutely sure what you are doing, leave this
1444 bool "3G/1G user/kernel split"
1445 config VMSPLIT_3G_OPT
1447 bool "3G/1G user/kernel split (for full 1G low memory)"
1449 bool "2G/2G user/kernel split"
1450 config VMSPLIT_2G_OPT
1452 bool "2G/2G user/kernel split (for full 2G low memory)"
1454 bool "1G/3G user/kernel split"
1459 default 0xB0000000 if VMSPLIT_3G_OPT
1460 default 0x80000000 if VMSPLIT_2G
1461 default 0x78000000 if VMSPLIT_2G_OPT
1462 default 0x40000000 if VMSPLIT_1G
1468 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1471 bool "PAE (Physical Address Extension) Support"
1472 depends on X86_32 && !HIGHMEM4G
1473 select PHYS_ADDR_T_64BIT
1476 PAE is required for NX support, and furthermore enables
1477 larger swapspace support for non-overcommit purposes. It
1478 has the cost of more pagetable lookup overhead, and also
1479 consumes more pagetable space per process.
1482 bool "Enable 5-level page tables support"
1484 select DYNAMIC_MEMORY_LAYOUT
1485 select SPARSEMEM_VMEMMAP
1488 5-level paging enables access to larger address space:
1489 upto 128 PiB of virtual address space and 4 PiB of
1490 physical address space.
1492 It will be supported by future Intel CPUs.
1494 A kernel with the option enabled can be booted on machines that
1495 support 4- or 5-level paging.
1497 See Documentation/x86/x86_64/5level-paging.rst for more
1502 config X86_DIRECT_GBPAGES
1506 Certain kernel features effectively disable kernel
1507 linear 1 GB mappings (even if the CPU otherwise
1508 supports them), so don't confuse the user by printing
1509 that we have them enabled.
1511 config X86_CPA_STATISTICS
1512 bool "Enable statistic for Change Page Attribute"
1515 Expose statistics about the Change Page Attribute mechanism, which
1516 helps to determine the effectiveness of preserving large and huge
1517 page mappings when mapping protections are changed.
1519 config AMD_MEM_ENCRYPT
1520 bool "AMD Secure Memory Encryption (SME) support"
1521 depends on X86_64 && CPU_SUP_AMD
1522 select DMA_COHERENT_POOL
1523 select DYNAMIC_PHYSICAL_MASK
1524 select ARCH_USE_MEMREMAP_PROT
1525 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1526 select INSTRUCTION_DECODER
1528 Say yes to enable support for the encryption of system memory.
1529 This requires an AMD processor that supports Secure Memory
1532 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1533 bool "Activate AMD Secure Memory Encryption (SME) by default"
1535 depends on AMD_MEM_ENCRYPT
1537 Say yes to have system memory encrypted by default if running on
1538 an AMD processor that supports Secure Memory Encryption (SME).
1540 If set to Y, then the encryption of system memory can be
1541 deactivated with the mem_encrypt=off command line option.
1543 If set to N, then the encryption of system memory can be
1544 activated with the mem_encrypt=on command line option.
1546 # Common NUMA Features
1548 bool "NUMA Memory Allocation and Scheduler Support"
1550 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1551 default y if X86_BIGSMP
1553 Enable NUMA (Non-Uniform Memory Access) support.
1555 The kernel will try to allocate memory used by a CPU on the
1556 local memory controller of the CPU and add some more
1557 NUMA awareness to the kernel.
1559 For 64-bit this is recommended if the system is Intel Core i7
1560 (or later), AMD Opteron, or EM64T NUMA.
1562 For 32-bit this is only needed if you boot a 32-bit
1563 kernel on a 64-bit NUMA platform.
1565 Otherwise, you should say N.
1569 prompt "Old style AMD Opteron NUMA detection"
1570 depends on X86_64 && NUMA && PCI
1572 Enable AMD NUMA node topology detection. You should say Y here if
1573 you have a multi processor AMD system. This uses an old method to
1574 read the NUMA configuration directly from the builtin Northbridge
1575 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1576 which also takes priority if both are compiled in.
1578 config X86_64_ACPI_NUMA
1580 prompt "ACPI NUMA detection"
1581 depends on X86_64 && NUMA && ACPI && PCI
1584 Enable ACPI SRAT based node topology detection.
1587 bool "NUMA emulation"
1590 Enable NUMA emulation. A flat machine will be split
1591 into virtual nodes when booted with "numa=fake=N", where N is the
1592 number of nodes. This is only useful for debugging.
1595 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1597 default "10" if MAXSMP
1598 default "6" if X86_64
1600 depends on NEED_MULTIPLE_NODES
1602 Specify the maximum number of NUMA Nodes available on the target
1603 system. Increases memory reserved to accommodate various tables.
1605 config ARCH_FLATMEM_ENABLE
1607 depends on X86_32 && !NUMA
1609 config ARCH_SPARSEMEM_ENABLE
1611 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1612 select SPARSEMEM_STATIC if X86_32
1613 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1615 config ARCH_SPARSEMEM_DEFAULT
1616 def_bool X86_64 || (NUMA && X86_32)
1618 config ARCH_SELECT_MEMORY_MODEL
1620 depends on ARCH_SPARSEMEM_ENABLE
1622 config ARCH_MEMORY_PROBE
1623 bool "Enable sysfs memory/probe interface"
1624 depends on X86_64 && MEMORY_HOTPLUG
1626 This option enables a sysfs memory/probe interface for testing.
1627 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1628 If you are unsure how to answer this question, answer N.
1630 config ARCH_PROC_KCORE_TEXT
1632 depends on X86_64 && PROC_KCORE
1634 config ILLEGAL_POINTER_VALUE
1637 default 0xdead000000000000 if X86_64
1639 config X86_PMEM_LEGACY_DEVICE
1642 config X86_PMEM_LEGACY
1643 tristate "Support non-standard NVDIMMs and ADR protected memory"
1644 depends on PHYS_ADDR_T_64BIT
1646 select X86_PMEM_LEGACY_DEVICE
1647 select NUMA_KEEP_MEMINFO if NUMA
1650 Treat memory marked using the non-standard e820 type of 12 as used
1651 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1652 The kernel will offer these regions to the 'pmem' driver so
1653 they can be used for persistent storage.
1658 bool "Allocate 3rd-level pagetables from highmem"
1661 The VM uses one page table entry for each page of physical memory.
1662 For systems with a lot of RAM, this can be wasteful of precious
1663 low memory. Setting this option will put user-space page table
1664 entries in high memory.
1666 config X86_CHECK_BIOS_CORRUPTION
1667 bool "Check for low memory corruption"
1669 Periodically check for memory corruption in low memory, which
1670 is suspected to be caused by BIOS. Even when enabled in the
1671 configuration, it is disabled at runtime. Enable it by
1672 setting "memory_corruption_check=1" on the kernel command
1673 line. By default it scans the low 64k of memory every 60
1674 seconds; see the memory_corruption_check_size and
1675 memory_corruption_check_period parameters in
1676 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1678 When enabled with the default parameters, this option has
1679 almost no overhead, as it reserves a relatively small amount
1680 of memory and scans it infrequently. It both detects corruption
1681 and prevents it from affecting the running system.
1683 It is, however, intended as a diagnostic tool; if repeatable
1684 BIOS-originated corruption always affects the same memory,
1685 you can use memmap= to prevent the kernel from using that
1688 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1689 bool "Set the default setting of memory_corruption_check"
1690 depends on X86_CHECK_BIOS_CORRUPTION
1693 Set whether the default state of memory_corruption_check is
1696 config X86_RESERVE_LOW
1697 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1701 Specify the amount of low memory to reserve for the BIOS.
1703 The first page contains BIOS data structures that the kernel
1704 must not use, so that page must always be reserved.
1706 By default we reserve the first 64K of physical RAM, as a
1707 number of BIOSes are known to corrupt that memory range
1708 during events such as suspend/resume or monitor cable
1709 insertion, so it must not be used by the kernel.
1711 You can set this to 4 if you are absolutely sure that you
1712 trust the BIOS to get all its memory reservations and usages
1713 right. If you know your BIOS have problems beyond the
1714 default 64K area, you can set this to 640 to avoid using the
1715 entire low memory range.
1717 If you have doubts about the BIOS (e.g. suspend/resume does
1718 not work or there's kernel crashes after certain hardware
1719 hotplug events) then you might want to enable
1720 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1721 typical corruption patterns.
1723 Leave this to the default value of 64 if you are unsure.
1725 config MATH_EMULATION
1727 depends on MODIFY_LDT_SYSCALL
1728 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1730 Linux can emulate a math coprocessor (used for floating point
1731 operations) if you don't have one. 486DX and Pentium processors have
1732 a math coprocessor built in, 486SX and 386 do not, unless you added
1733 a 487DX or 387, respectively. (The messages during boot time can
1734 give you some hints here ["man dmesg"].) Everyone needs either a
1735 coprocessor or this emulation.
1737 If you don't have a math coprocessor, you need to say Y here; if you
1738 say Y here even though you have a coprocessor, the coprocessor will
1739 be used nevertheless. (This behavior can be changed with the kernel
1740 command line option "no387", which comes handy if your coprocessor
1741 is broken. Try "man bootparam" or see the documentation of your boot
1742 loader (lilo or loadlin) about how to pass options to the kernel at
1743 boot time.) This means that it is a good idea to say Y here if you
1744 intend to use this kernel on different machines.
1746 More information about the internals of the Linux math coprocessor
1747 emulation can be found in <file:arch/x86/math-emu/README>.
1749 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1750 kernel, it won't hurt.
1754 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1756 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1757 the Memory Type Range Registers (MTRRs) may be used to control
1758 processor access to memory ranges. This is most useful if you have
1759 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1760 allows bus write transfers to be combined into a larger transfer
1761 before bursting over the PCI/AGP bus. This can increase performance
1762 of image write operations 2.5 times or more. Saying Y here creates a
1763 /proc/mtrr file which may be used to manipulate your processor's
1764 MTRRs. Typically the X server should use this.
1766 This code has a reasonably generic interface so that similar
1767 control registers on other processors can be easily supported
1770 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1771 Registers (ARRs) which provide a similar functionality to MTRRs. For
1772 these, the ARRs are used to emulate the MTRRs.
1773 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1774 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1775 write-combining. All of these processors are supported by this code
1776 and it makes sense to say Y here if you have one of them.
1778 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1779 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1780 can lead to all sorts of problems, so it's good to say Y here.
1782 You can safely say Y even if your machine doesn't have MTRRs, you'll
1783 just add about 9 KB to your kernel.
1785 See <file:Documentation/x86/mtrr.rst> for more information.
1787 config MTRR_SANITIZER
1789 prompt "MTRR cleanup support"
1792 Convert MTRR layout from continuous to discrete, so X drivers can
1793 add writeback entries.
1795 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1796 The largest mtrr entry size for a continuous block can be set with
1801 config MTRR_SANITIZER_ENABLE_DEFAULT
1802 int "MTRR cleanup enable value (0-1)"
1805 depends on MTRR_SANITIZER
1807 Enable mtrr cleanup default value
1809 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1810 int "MTRR cleanup spare reg num (0-7)"
1813 depends on MTRR_SANITIZER
1815 mtrr cleanup spare entries default, it can be changed via
1816 mtrr_spare_reg_nr=N on the kernel command line.
1820 prompt "x86 PAT support" if EXPERT
1823 Use PAT attributes to setup page level cache control.
1825 PATs are the modern equivalents of MTRRs and are much more
1826 flexible than MTRRs.
1828 Say N here if you see bootup problems (boot crash, boot hang,
1829 spontaneous reboots) or a non-working video driver.
1833 config ARCH_USES_PG_UNCACHED
1839 prompt "x86 architectural random number generator" if EXPERT
1841 Enable the x86 architectural RDRAND instruction
1842 (Intel Bull Mountain technology) to generate random numbers.
1843 If supported, this is a high bandwidth, cryptographically
1844 secure hardware random number generator.
1848 prompt "Supervisor Mode Access Prevention" if EXPERT
1850 Supervisor Mode Access Prevention (SMAP) is a security
1851 feature in newer Intel processors. There is a small
1852 performance cost if this enabled and turned on; there is
1853 also a small increase in the kernel size if this is enabled.
1859 prompt "User Mode Instruction Prevention" if EXPERT
1861 User Mode Instruction Prevention (UMIP) is a security feature in
1862 some x86 processors. If enabled, a general protection fault is
1863 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1864 executed in user mode. These instructions unnecessarily expose
1865 information about the hardware state.
1867 The vast majority of applications do not use these instructions.
1868 For the very few that do, software emulation is provided in
1869 specific cases in protected and virtual-8086 modes. Emulated
1872 config X86_INTEL_MEMORY_PROTECTION_KEYS
1873 prompt "Memory Protection Keys"
1875 # Note: only available in 64-bit mode
1876 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1877 select ARCH_USES_HIGH_VMA_FLAGS
1878 select ARCH_HAS_PKEYS
1880 Memory Protection Keys provides a mechanism for enforcing
1881 page-based protections, but without requiring modification of the
1882 page tables when an application changes protection domains.
1884 For details, see Documentation/core-api/protection-keys.rst
1889 prompt "TSX enable mode"
1890 depends on CPU_SUP_INTEL
1891 default X86_INTEL_TSX_MODE_OFF
1893 Intel's TSX (Transactional Synchronization Extensions) feature
1894 allows to optimize locking protocols through lock elision which
1895 can lead to a noticeable performance boost.
1897 On the other hand it has been shown that TSX can be exploited
1898 to form side channel attacks (e.g. TAA) and chances are there
1899 will be more of those attacks discovered in the future.
1901 Therefore TSX is not enabled by default (aka tsx=off). An admin
1902 might override this decision by tsx=on the command line parameter.
1903 Even with TSX enabled, the kernel will attempt to enable the best
1904 possible TAA mitigation setting depending on the microcode available
1905 for the particular machine.
1907 This option allows to set the default tsx mode between tsx=on, =off
1908 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1911 Say off if not sure, auto if TSX is in use but it should be used on safe
1912 platforms or on if TSX is in use and the security aspect of tsx is not
1915 config X86_INTEL_TSX_MODE_OFF
1918 TSX is disabled if possible - equals to tsx=off command line parameter.
1920 config X86_INTEL_TSX_MODE_ON
1923 TSX is always enabled on TSX capable HW - equals the tsx=on command
1926 config X86_INTEL_TSX_MODE_AUTO
1929 TSX is enabled on TSX capable HW that is believed to be safe against
1930 side channel attacks- equals the tsx=auto command line parameter.
1934 bool "EFI runtime service support"
1937 select EFI_RUNTIME_WRAPPERS
1939 This enables the kernel to use EFI runtime services that are
1940 available (such as the EFI variable services).
1942 This option is only useful on systems that have EFI firmware.
1943 In addition, you should use the latest ELILO loader available
1944 at <http://elilo.sourceforge.net> in order to take advantage
1945 of EFI runtime services. However, even with this option, the
1946 resultant kernel should continue to boot on existing non-EFI
1950 bool "EFI stub support"
1951 depends on EFI && !X86_USE_3DNOW
1952 depends on $(cc-option,-mabi=ms) || X86_32
1955 This kernel feature allows a bzImage to be loaded directly
1956 by EFI firmware without the use of a bootloader.
1958 See Documentation/admin-guide/efi-stub.rst for more information.
1961 bool "EFI mixed-mode support"
1962 depends on EFI_STUB && X86_64
1964 Enabling this feature allows a 64-bit kernel to be booted
1965 on a 32-bit firmware, provided that your CPU supports 64-bit
1968 Note that it is not possible to boot a mixed-mode enabled
1969 kernel via the EFI boot stub - a bootloader that supports
1970 the EFI handover protocol must be used.
1974 source "kernel/Kconfig.hz"
1977 bool "kexec system call"
1980 kexec is a system call that implements the ability to shutdown your
1981 current kernel, and to start another kernel. It is like a reboot
1982 but it is independent of the system firmware. And like a reboot
1983 you can start any kernel with it, not just Linux.
1985 The name comes from the similarity to the exec system call.
1987 It is an ongoing process to be certain the hardware in a machine
1988 is properly shutdown, so do not be surprised if this code does not
1989 initially work for you. As of this writing the exact hardware
1990 interface is strongly in flux, so no good recommendation can be
1994 bool "kexec file based system call"
1999 depends on CRYPTO_SHA256=y
2001 This is new version of kexec system call. This system call is
2002 file based and takes file descriptors as system call argument
2003 for kernel and initramfs as opposed to list of segments as
2004 accepted by previous system call.
2006 config ARCH_HAS_KEXEC_PURGATORY
2010 bool "Verify kernel signature during kexec_file_load() syscall"
2011 depends on KEXEC_FILE
2014 This option makes the kexec_file_load() syscall check for a valid
2015 signature of the kernel image. The image can still be loaded without
2016 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2017 there's a signature that we can check, then it must be valid.
2019 In addition to this option, you need to enable signature
2020 verification for the corresponding kernel image type being
2021 loaded in order for this to work.
2023 config KEXEC_SIG_FORCE
2024 bool "Require a valid signature in kexec_file_load() syscall"
2025 depends on KEXEC_SIG
2027 This option makes kernel signature verification mandatory for
2028 the kexec_file_load() syscall.
2030 config KEXEC_BZIMAGE_VERIFY_SIG
2031 bool "Enable bzImage signature verification support"
2032 depends on KEXEC_SIG
2033 depends on SIGNED_PE_FILE_VERIFICATION
2034 select SYSTEM_TRUSTED_KEYRING
2036 Enable bzImage signature verification support.
2039 bool "kernel crash dumps"
2040 depends on X86_64 || (X86_32 && HIGHMEM)
2042 Generate crash dump after being started by kexec.
2043 This should be normally only set in special crash dump kernels
2044 which are loaded in the main kernel with kexec-tools into
2045 a specially reserved region and then later executed after
2046 a crash by kdump/kexec. The crash dump kernel must be compiled
2047 to a memory address not used by the main kernel or BIOS using
2048 PHYSICAL_START, or it must be built as a relocatable image
2049 (CONFIG_RELOCATABLE=y).
2050 For more details see Documentation/admin-guide/kdump/kdump.rst
2054 depends on KEXEC && HIBERNATION
2056 Jump between original kernel and kexeced kernel and invoke
2057 code in physical address mode via KEXEC
2059 config PHYSICAL_START
2060 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2063 This gives the physical address where the kernel is loaded.
2065 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2066 bzImage will decompress itself to above physical address and
2067 run from there. Otherwise, bzImage will run from the address where
2068 it has been loaded by the boot loader and will ignore above physical
2071 In normal kdump cases one does not have to set/change this option
2072 as now bzImage can be compiled as a completely relocatable image
2073 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2074 address. This option is mainly useful for the folks who don't want
2075 to use a bzImage for capturing the crash dump and want to use a
2076 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2077 to be specifically compiled to run from a specific memory area
2078 (normally a reserved region) and this option comes handy.
2080 So if you are using bzImage for capturing the crash dump,
2081 leave the value here unchanged to 0x1000000 and set
2082 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2083 for capturing the crash dump change this value to start of
2084 the reserved region. In other words, it can be set based on
2085 the "X" value as specified in the "crashkernel=YM@XM"
2086 command line boot parameter passed to the panic-ed
2087 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2088 for more details about crash dumps.
2090 Usage of bzImage for capturing the crash dump is recommended as
2091 one does not have to build two kernels. Same kernel can be used
2092 as production kernel and capture kernel. Above option should have
2093 gone away after relocatable bzImage support is introduced. But it
2094 is present because there are users out there who continue to use
2095 vmlinux for dump capture. This option should go away down the
2098 Don't change this unless you know what you are doing.
2101 bool "Build a relocatable kernel"
2104 This builds a kernel image that retains relocation information
2105 so it can be loaded someplace besides the default 1MB.
2106 The relocations tend to make the kernel binary about 10% larger,
2107 but are discarded at runtime.
2109 One use is for the kexec on panic case where the recovery kernel
2110 must live at a different physical address than the primary
2113 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2114 it has been loaded at and the compile time physical address
2115 (CONFIG_PHYSICAL_START) is used as the minimum location.
2117 config RANDOMIZE_BASE
2118 bool "Randomize the address of the kernel image (KASLR)"
2119 depends on RELOCATABLE
2122 In support of Kernel Address Space Layout Randomization (KASLR),
2123 this randomizes the physical address at which the kernel image
2124 is decompressed and the virtual address where the kernel
2125 image is mapped, as a security feature that deters exploit
2126 attempts relying on knowledge of the location of kernel
2129 On 64-bit, the kernel physical and virtual addresses are
2130 randomized separately. The physical address will be anywhere
2131 between 16MB and the top of physical memory (up to 64TB). The
2132 virtual address will be randomized from 16MB up to 1GB (9 bits
2133 of entropy). Note that this also reduces the memory space
2134 available to kernel modules from 1.5GB to 1GB.
2136 On 32-bit, the kernel physical and virtual addresses are
2137 randomized together. They will be randomized from 16MB up to
2138 512MB (8 bits of entropy).
2140 Entropy is generated using the RDRAND instruction if it is
2141 supported. If RDTSC is supported, its value is mixed into
2142 the entropy pool as well. If neither RDRAND nor RDTSC are
2143 supported, then entropy is read from the i8254 timer. The
2144 usable entropy is limited by the kernel being built using
2145 2GB addressing, and that PHYSICAL_ALIGN must be at a
2146 minimum of 2MB. As a result, only 10 bits of entropy are
2147 theoretically possible, but the implementations are further
2148 limited due to memory layouts.
2152 # Relocation on x86 needs some additional build support
2153 config X86_NEED_RELOCS
2155 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2157 config PHYSICAL_ALIGN
2158 hex "Alignment value to which kernel should be aligned"
2160 range 0x2000 0x1000000 if X86_32
2161 range 0x200000 0x1000000 if X86_64
2163 This value puts the alignment restrictions on physical address
2164 where kernel is loaded and run from. Kernel is compiled for an
2165 address which meets above alignment restriction.
2167 If bootloader loads the kernel at a non-aligned address and
2168 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2169 address aligned to above value and run from there.
2171 If bootloader loads the kernel at a non-aligned address and
2172 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2173 load address and decompress itself to the address it has been
2174 compiled for and run from there. The address for which kernel is
2175 compiled already meets above alignment restrictions. Hence the
2176 end result is that kernel runs from a physical address meeting
2177 above alignment restrictions.
2179 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2180 this value must be a multiple of 0x200000.
2182 Don't change this unless you know what you are doing.
2184 config DYNAMIC_MEMORY_LAYOUT
2187 This option makes base addresses of vmalloc and vmemmap as well as
2188 __PAGE_OFFSET movable during boot.
2190 config RANDOMIZE_MEMORY
2191 bool "Randomize the kernel memory sections"
2193 depends on RANDOMIZE_BASE
2194 select DYNAMIC_MEMORY_LAYOUT
2195 default RANDOMIZE_BASE
2197 Randomizes the base virtual address of kernel memory sections
2198 (physical memory mapping, vmalloc & vmemmap). This security feature
2199 makes exploits relying on predictable memory locations less reliable.
2201 The order of allocations remains unchanged. Entropy is generated in
2202 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2203 configuration have in average 30,000 different possible virtual
2204 addresses for each memory section.
2208 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2209 hex "Physical memory mapping padding" if EXPERT
2210 depends on RANDOMIZE_MEMORY
2211 default "0xa" if MEMORY_HOTPLUG
2213 range 0x1 0x40 if MEMORY_HOTPLUG
2216 Define the padding in terabytes added to the existing physical
2217 memory size during kernel memory randomization. It is useful
2218 for memory hotplug support but reduces the entropy available for
2219 address randomization.
2221 If unsure, leave at the default value.
2227 config BOOTPARAM_HOTPLUG_CPU0
2228 bool "Set default setting of cpu0_hotpluggable"
2229 depends on HOTPLUG_CPU
2231 Set whether default state of cpu0_hotpluggable is on or off.
2233 Say Y here to enable CPU0 hotplug by default. If this switch
2234 is turned on, there is no need to give cpu0_hotplug kernel
2235 parameter and the CPU0 hotplug feature is enabled by default.
2237 Please note: there are two known CPU0 dependencies if you want
2238 to enable the CPU0 hotplug feature either by this switch or by
2239 cpu0_hotplug kernel parameter.
2241 First, resume from hibernate or suspend always starts from CPU0.
2242 So hibernate and suspend are prevented if CPU0 is offline.
2244 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2245 offline if any interrupt can not migrate out of CPU0. There may
2246 be other CPU0 dependencies.
2248 Please make sure the dependencies are under your control before
2249 you enable this feature.
2251 Say N if you don't want to enable CPU0 hotplug feature by default.
2252 You still can enable the CPU0 hotplug feature at boot by kernel
2253 parameter cpu0_hotplug.
2255 config DEBUG_HOTPLUG_CPU0
2257 prompt "Debug CPU0 hotplug"
2258 depends on HOTPLUG_CPU
2260 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2261 soon as possible and boots up userspace with CPU0 offlined. User
2262 can online CPU0 back after boot time.
2264 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2265 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2266 compilation or giving cpu0_hotplug kernel parameter at boot.
2272 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2273 depends on COMPAT_32
2275 Certain buggy versions of glibc will crash if they are
2276 presented with a 32-bit vDSO that is not mapped at the address
2277 indicated in its segment table.
2279 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2280 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2281 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2282 the only released version with the bug, but OpenSUSE 9
2283 contains a buggy "glibc 2.3.2".
2285 The symptom of the bug is that everything crashes on startup, saying:
2286 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2288 Saying Y here changes the default value of the vdso32 boot
2289 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2290 This works around the glibc bug but hurts performance.
2292 If unsure, say N: if you are compiling your own kernel, you
2293 are unlikely to be using a buggy version of glibc.
2296 prompt "vsyscall table for legacy applications"
2298 default LEGACY_VSYSCALL_XONLY
2300 Legacy user code that does not know how to find the vDSO expects
2301 to be able to issue three syscalls by calling fixed addresses in
2302 kernel space. Since this location is not randomized with ASLR,
2303 it can be used to assist security vulnerability exploitation.
2305 This setting can be changed at boot time via the kernel command
2306 line parameter vsyscall=[emulate|xonly|none].
2308 On a system with recent enough glibc (2.14 or newer) and no
2309 static binaries, you can say None without a performance penalty
2310 to improve security.
2312 If unsure, select "Emulate execution only".
2314 config LEGACY_VSYSCALL_EMULATE
2315 bool "Full emulation"
2317 The kernel traps and emulates calls into the fixed vsyscall
2318 address mapping. This makes the mapping non-executable, but
2319 it still contains readable known contents, which could be
2320 used in certain rare security vulnerability exploits. This
2321 configuration is recommended when using legacy userspace
2322 that still uses vsyscalls along with legacy binary
2323 instrumentation tools that require code to be readable.
2325 An example of this type of legacy userspace is running
2326 Pin on an old binary that still uses vsyscalls.
2328 config LEGACY_VSYSCALL_XONLY
2329 bool "Emulate execution only"
2331 The kernel traps and emulates calls into the fixed vsyscall
2332 address mapping and does not allow reads. This
2333 configuration is recommended when userspace might use the
2334 legacy vsyscall area but support for legacy binary
2335 instrumentation of legacy code is not needed. It mitigates
2336 certain uses of the vsyscall area as an ASLR-bypassing
2339 config LEGACY_VSYSCALL_NONE
2342 There will be no vsyscall mapping at all. This will
2343 eliminate any risk of ASLR bypass due to the vsyscall
2344 fixed address mapping. Attempts to use the vsyscalls
2345 will be reported to dmesg, so that either old or
2346 malicious userspace programs can be identified.
2351 bool "Built-in kernel command line"
2353 Allow for specifying boot arguments to the kernel at
2354 build time. On some systems (e.g. embedded ones), it is
2355 necessary or convenient to provide some or all of the
2356 kernel boot arguments with the kernel itself (that is,
2357 to not rely on the boot loader to provide them.)
2359 To compile command line arguments into the kernel,
2360 set this option to 'Y', then fill in the
2361 boot arguments in CONFIG_CMDLINE.
2363 Systems with fully functional boot loaders (i.e. non-embedded)
2364 should leave this option set to 'N'.
2367 string "Built-in kernel command string"
2368 depends on CMDLINE_BOOL
2371 Enter arguments here that should be compiled into the kernel
2372 image and used at boot time. If the boot loader provides a
2373 command line at boot time, it is appended to this string to
2374 form the full kernel command line, when the system boots.
2376 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2377 change this behavior.
2379 In most cases, the command line (whether built-in or provided
2380 by the boot loader) should specify the device for the root
2383 config CMDLINE_OVERRIDE
2384 bool "Built-in command line overrides boot loader arguments"
2385 depends on CMDLINE_BOOL && CMDLINE != ""
2387 Set this option to 'Y' to have the kernel ignore the boot loader
2388 command line, and use ONLY the built-in command line.
2390 This is used to work around broken boot loaders. This should
2391 be set to 'N' under normal conditions.
2393 config MODIFY_LDT_SYSCALL
2394 bool "Enable the LDT (local descriptor table)" if EXPERT
2397 Linux can allow user programs to install a per-process x86
2398 Local Descriptor Table (LDT) using the modify_ldt(2) system
2399 call. This is required to run 16-bit or segmented code such as
2400 DOSEMU or some Wine programs. It is also used by some very old
2401 threading libraries.
2403 Enabling this feature adds a small amount of overhead to
2404 context switches and increases the low-level kernel attack
2405 surface. Disabling it removes the modify_ldt(2) system call.
2407 Saying 'N' here may make sense for embedded or server kernels.
2409 source "kernel/livepatch/Kconfig"
2413 config ARCH_HAS_ADD_PAGES
2415 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2417 config ARCH_ENABLE_MEMORY_HOTPLUG
2419 depends on X86_64 || (X86_32 && HIGHMEM)
2421 config ARCH_ENABLE_MEMORY_HOTREMOVE
2423 depends on MEMORY_HOTPLUG
2425 config USE_PERCPU_NUMA_NODE_ID
2429 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2431 depends on X86_64 || X86_PAE
2433 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2435 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2437 config ARCH_ENABLE_THP_MIGRATION
2439 depends on X86_64 && TRANSPARENT_HUGEPAGE
2441 menu "Power management and ACPI options"
2443 config ARCH_HIBERNATION_HEADER
2445 depends on HIBERNATION
2447 source "kernel/power/Kconfig"
2449 source "drivers/acpi/Kconfig"
2451 source "drivers/sfi/Kconfig"
2458 tristate "APM (Advanced Power Management) BIOS support"
2459 depends on X86_32 && PM_SLEEP
2461 APM is a BIOS specification for saving power using several different
2462 techniques. This is mostly useful for battery powered laptops with
2463 APM compliant BIOSes. If you say Y here, the system time will be
2464 reset after a RESUME operation, the /proc/apm device will provide
2465 battery status information, and user-space programs will receive
2466 notification of APM "events" (e.g. battery status change).
2468 If you select "Y" here, you can disable actual use of the APM
2469 BIOS by passing the "apm=off" option to the kernel at boot time.
2471 Note that the APM support is almost completely disabled for
2472 machines with more than one CPU.
2474 In order to use APM, you will need supporting software. For location
2475 and more information, read <file:Documentation/power/apm-acpi.rst>
2476 and the Battery Powered Linux mini-HOWTO, available from
2477 <http://www.tldp.org/docs.html#howto>.
2479 This driver does not spin down disk drives (see the hdparm(8)
2480 manpage ("man 8 hdparm") for that), and it doesn't turn off
2481 VESA-compliant "green" monitors.
2483 This driver does not support the TI 4000M TravelMate and the ACER
2484 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2485 desktop machines also don't have compliant BIOSes, and this driver
2486 may cause those machines to panic during the boot phase.
2488 Generally, if you don't have a battery in your machine, there isn't
2489 much point in using this driver and you should say N. If you get
2490 random kernel OOPSes or reboots that don't seem to be related to
2491 anything, try disabling/enabling this option (or disabling/enabling
2494 Some other things you should try when experiencing seemingly random,
2497 1) make sure that you have enough swap space and that it is
2499 2) pass the "no-hlt" option to the kernel
2500 3) switch on floating point emulation in the kernel and pass
2501 the "no387" option to the kernel
2502 4) pass the "floppy=nodma" option to the kernel
2503 5) pass the "mem=4M" option to the kernel (thereby disabling
2504 all but the first 4 MB of RAM)
2505 6) make sure that the CPU is not over clocked.
2506 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2507 8) disable the cache from your BIOS settings
2508 9) install a fan for the video card or exchange video RAM
2509 10) install a better fan for the CPU
2510 11) exchange RAM chips
2511 12) exchange the motherboard.
2513 To compile this driver as a module, choose M here: the
2514 module will be called apm.
2518 config APM_IGNORE_USER_SUSPEND
2519 bool "Ignore USER SUSPEND"
2521 This option will ignore USER SUSPEND requests. On machines with a
2522 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2523 series notebooks, it is necessary to say Y because of a BIOS bug.
2525 config APM_DO_ENABLE
2526 bool "Enable PM at boot time"
2528 Enable APM features at boot time. From page 36 of the APM BIOS
2529 specification: "When disabled, the APM BIOS does not automatically
2530 power manage devices, enter the Standby State, enter the Suspend
2531 State, or take power saving steps in response to CPU Idle calls."
2532 This driver will make CPU Idle calls when Linux is idle (unless this
2533 feature is turned off -- see "Do CPU IDLE calls", below). This
2534 should always save battery power, but more complicated APM features
2535 will be dependent on your BIOS implementation. You may need to turn
2536 this option off if your computer hangs at boot time when using APM
2537 support, or if it beeps continuously instead of suspending. Turn
2538 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2539 T400CDT. This is off by default since most machines do fine without
2544 bool "Make CPU Idle calls when idle"
2546 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2547 On some machines, this can activate improved power savings, such as
2548 a slowed CPU clock rate, when the machine is idle. These idle calls
2549 are made after the idle loop has run for some length of time (e.g.,
2550 333 mS). On some machines, this will cause a hang at boot time or
2551 whenever the CPU becomes idle. (On machines with more than one CPU,
2552 this option does nothing.)
2554 config APM_DISPLAY_BLANK
2555 bool "Enable console blanking using APM"
2557 Enable console blanking using the APM. Some laptops can use this to
2558 turn off the LCD backlight when the screen blanker of the Linux
2559 virtual console blanks the screen. Note that this is only used by
2560 the virtual console screen blanker, and won't turn off the backlight
2561 when using the X Window system. This also doesn't have anything to
2562 do with your VESA-compliant power-saving monitor. Further, this
2563 option doesn't work for all laptops -- it might not turn off your
2564 backlight at all, or it might print a lot of errors to the console,
2565 especially if you are using gpm.
2567 config APM_ALLOW_INTS
2568 bool "Allow interrupts during APM BIOS calls"
2570 Normally we disable external interrupts while we are making calls to
2571 the APM BIOS as a measure to lessen the effects of a badly behaving
2572 BIOS implementation. The BIOS should reenable interrupts if it
2573 needs to. Unfortunately, some BIOSes do not -- especially those in
2574 many of the newer IBM Thinkpads. If you experience hangs when you
2575 suspend, try setting this to Y. Otherwise, say N.
2579 source "drivers/cpufreq/Kconfig"
2581 source "drivers/cpuidle/Kconfig"
2583 source "drivers/idle/Kconfig"
2588 menu "Bus options (PCI etc.)"
2591 prompt "PCI access mode"
2592 depends on X86_32 && PCI
2595 On PCI systems, the BIOS can be used to detect the PCI devices and
2596 determine their configuration. However, some old PCI motherboards
2597 have BIOS bugs and may crash if this is done. Also, some embedded
2598 PCI-based systems don't have any BIOS at all. Linux can also try to
2599 detect the PCI hardware directly without using the BIOS.
2601 With this option, you can specify how Linux should detect the
2602 PCI devices. If you choose "BIOS", the BIOS will be used,
2603 if you choose "Direct", the BIOS won't be used, and if you
2604 choose "MMConfig", then PCI Express MMCONFIG will be used.
2605 If you choose "Any", the kernel will try MMCONFIG, then the
2606 direct access method and falls back to the BIOS if that doesn't
2607 work. If unsure, go with the default, which is "Any".
2612 config PCI_GOMMCONFIG
2629 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2631 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2634 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2637 bool "Support mmconfig PCI config space access" if X86_64
2639 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2640 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2644 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2648 depends on PCI && XEN
2651 config MMCONF_FAM10H
2653 depends on X86_64 && PCI_MMCONFIG && ACPI
2655 config PCI_CNB20LE_QUIRK
2656 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2659 Read the PCI windows out of the CNB20LE host bridge. This allows
2660 PCI hotplug to work on systems with the CNB20LE chipset which do
2663 There's no public spec for this chipset, and this functionality
2664 is known to be incomplete.
2666 You should say N unless you know you need this.
2669 bool "ISA bus support on modern systems" if EXPERT
2671 Expose ISA bus device drivers and options available for selection and
2672 configuration. Enable this option if your target machine has an ISA
2673 bus. ISA is an older system, displaced by PCI and newer bus
2674 architectures -- if your target machine is modern, it probably does
2675 not have an ISA bus.
2679 # x86_64 have no ISA slots, but can have ISA-style DMA.
2681 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2684 Enables ISA-style DMA support for devices requiring such controllers.
2692 Find out whether you have ISA slots on your motherboard. ISA is the
2693 name of a bus system, i.e. the way the CPU talks to the other stuff
2694 inside your box. Other bus systems are PCI, EISA, MicroChannel
2695 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2696 newer boards don't support it. If you have ISA, say Y, otherwise N.
2699 tristate "NatSemi SCx200 support"
2701 This provides basic support for National Semiconductor's
2702 (now AMD's) Geode processors. The driver probes for the
2703 PCI-IDs of several on-chip devices, so its a good dependency
2704 for other scx200_* drivers.
2706 If compiled as a module, the driver is named scx200.
2708 config SCx200HR_TIMER
2709 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2713 This driver provides a clocksource built upon the on-chip
2714 27MHz high-resolution timer. Its also a workaround for
2715 NSC Geode SC-1100's buggy TSC, which loses time when the
2716 processor goes idle (as is done by the scheduler). The
2717 other workaround is idle=poll boot option.
2720 bool "One Laptop Per Child support"
2728 Add support for detecting the unique features of the OLPC
2732 bool "OLPC XO-1 Power Management"
2733 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2735 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2738 bool "OLPC XO-1 Real Time Clock"
2739 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2741 Add support for the XO-1 real time clock, which can be used as a
2742 programmable wakeup source.
2745 bool "OLPC XO-1 SCI extras"
2746 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2750 Add support for SCI-based features of the OLPC XO-1 laptop:
2751 - EC-driven system wakeups
2755 - AC adapter status updates
2756 - Battery status updates
2758 config OLPC_XO15_SCI
2759 bool "OLPC XO-1.5 SCI extras"
2760 depends on OLPC && ACPI
2763 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2764 - EC-driven system wakeups
2765 - AC adapter status updates
2766 - Battery status updates
2769 bool "PCEngines ALIX System Support (LED setup)"
2772 This option enables system support for the PCEngines ALIX.
2773 At present this just sets up LEDs for GPIO control on
2774 ALIX2/3/6 boards. However, other system specific setup should
2777 Note: You must still enable the drivers for GPIO and LED support
2778 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2780 Note: You have to set alix.force=1 for boards with Award BIOS.
2783 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2786 This option enables system support for the Soekris Engineering net5501.
2789 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2793 This option enables system support for the Traverse Technologies GEOS.
2796 bool "Technologic Systems TS-5500 platform support"
2798 select CHECK_SIGNATURE
2802 This option enables system support for the Technologic Systems TS-5500.
2808 depends on CPU_SUP_AMD && PCI
2811 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2813 Firmwares often provide initial graphics framebuffers so the BIOS,
2814 bootloader or kernel can show basic video-output during boot for
2815 user-guidance and debugging. Historically, x86 used the VESA BIOS
2816 Extensions and EFI-framebuffers for this, which are mostly limited
2818 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2819 framebuffers so the new generic system-framebuffer drivers can be
2820 used on x86. If the framebuffer is not compatible with the generic
2821 modes, it is advertised as fallback platform framebuffer so legacy
2822 drivers like efifb, vesafb and uvesafb can pick it up.
2823 If this option is not selected, all system framebuffers are always
2824 marked as fallback platform framebuffers as usual.
2826 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2827 not be able to pick up generic system framebuffers if this option
2828 is selected. You are highly encouraged to enable simplefb as
2829 replacement if you select this option. simplefb can correctly deal
2830 with generic system framebuffers. But you should still keep vesafb
2831 and others enabled as fallback if a system framebuffer is
2832 incompatible with simplefb.
2839 menu "Binary Emulations"
2841 config IA32_EMULATION
2842 bool "IA32 Emulation"
2844 select ARCH_WANT_OLD_COMPAT_IPC
2846 select COMPAT_BINFMT_ELF
2847 select COMPAT_OLD_SIGACTION
2849 Include code to run legacy 32-bit programs under a
2850 64-bit kernel. You should likely turn this on, unless you're
2851 100% sure that you don't have any 32-bit programs left.
2854 tristate "IA32 a.out support"
2855 depends on IA32_EMULATION
2858 Support old a.out binaries in the 32bit emulation.
2861 bool "x32 ABI for 64-bit mode"
2864 Include code to run binaries for the x32 native 32-bit ABI
2865 for 64-bit processors. An x32 process gets access to the
2866 full 64-bit register file and wide data path while leaving
2867 pointers at 32 bits for smaller memory footprint.
2869 You will need a recent binutils (2.22 or later) with
2870 elf32_x86_64 support enabled to compile a kernel with this
2875 depends on IA32_EMULATION || X86_32
2877 select OLD_SIGSUSPEND3
2881 depends on IA32_EMULATION || X86_X32
2884 config COMPAT_FOR_U64_ALIGNMENT
2887 config SYSVIPC_COMPAT
2895 config HAVE_ATOMIC_IOMAP
2899 source "drivers/firmware/Kconfig"
2901 source "arch/x86/kvm/Kconfig"
2903 source "arch/x86/Kconfig.assembler"