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_WANT_LD_ORPHAN_WARN
104 select ARCH_WANTS_THP_SWAP if X86_64
105 select BUILDTIME_TABLE_SORT
107 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
108 select CLOCKSOURCE_WATCHDOG
109 select DCACHE_WORD_ACCESS
110 select EDAC_ATOMIC_SCRUB
112 select GENERIC_CLOCKEVENTS
113 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
114 select GENERIC_CLOCKEVENTS_MIN_ADJUST
115 select GENERIC_CMOS_UPDATE
116 select GENERIC_CPU_AUTOPROBE
117 select GENERIC_CPU_VULNERABILITIES
118 select GENERIC_EARLY_IOREMAP
120 select GENERIC_FIND_FIRST_BIT
122 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
123 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
124 select GENERIC_IRQ_MIGRATION if SMP
125 select GENERIC_IRQ_PROBE
126 select GENERIC_IRQ_RESERVATION_MODE
127 select GENERIC_IRQ_SHOW
128 select GENERIC_PENDING_IRQ if SMP
129 select GENERIC_PTDUMP
130 select GENERIC_SMP_IDLE_THREAD
131 select GENERIC_STRNCPY_FROM_USER
132 select GENERIC_STRNLEN_USER
133 select GENERIC_TIME_VSYSCALL
134 select GENERIC_GETTIMEOFDAY
135 select GENERIC_VDSO_TIME_NS
136 select GUP_GET_PTE_LOW_HIGH if X86_PAE
137 select HARDIRQS_SW_RESEND
138 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
139 select HAVE_ACPI_APEI if ACPI
140 select HAVE_ACPI_APEI_NMI if ACPI
141 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
142 select HAVE_ARCH_AUDITSYSCALL
143 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
144 select HAVE_ARCH_JUMP_LABEL
145 select HAVE_ARCH_JUMP_LABEL_RELATIVE
146 select HAVE_ARCH_KASAN if X86_64
147 select HAVE_ARCH_KASAN_VMALLOC if X86_64
148 select HAVE_ARCH_KGDB
149 select HAVE_ARCH_MMAP_RND_BITS if MMU
150 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
151 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
152 select HAVE_ARCH_PREL32_RELOCATIONS
153 select HAVE_ARCH_SECCOMP_FILTER
154 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
155 select HAVE_ARCH_STACKLEAK
156 select HAVE_ARCH_TRACEHOOK
157 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
158 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
159 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
160 select HAVE_ARCH_VMAP_STACK if X86_64
161 select HAVE_ARCH_WITHIN_STACK_FRAMES
162 select HAVE_ASM_MODVERSIONS
163 select HAVE_CMPXCHG_DOUBLE
164 select HAVE_CMPXCHG_LOCAL
165 select HAVE_CONTEXT_TRACKING if X86_64
166 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
167 select HAVE_C_RECORDMCOUNT
168 select HAVE_DEBUG_KMEMLEAK
169 select HAVE_DMA_CONTIGUOUS
170 select HAVE_DYNAMIC_FTRACE
171 select HAVE_DYNAMIC_FTRACE_WITH_REGS
172 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
174 select HAVE_EFFICIENT_UNALIGNED_ACCESS
176 select HAVE_EXIT_THREAD
178 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
179 select HAVE_FTRACE_MCOUNT_RECORD
180 select HAVE_FUNCTION_GRAPH_TRACER
181 select HAVE_FUNCTION_TRACER
182 select HAVE_GCC_PLUGINS
183 select HAVE_HW_BREAKPOINT
185 select HAVE_IOREMAP_PROT
186 select HAVE_IRQ_TIME_ACCOUNTING
187 select HAVE_KERNEL_BZIP2
188 select HAVE_KERNEL_GZIP
189 select HAVE_KERNEL_LZ4
190 select HAVE_KERNEL_LZMA
191 select HAVE_KERNEL_LZO
192 select HAVE_KERNEL_XZ
193 select HAVE_KERNEL_ZSTD
195 select HAVE_KPROBES_ON_FTRACE
196 select HAVE_FUNCTION_ERROR_INJECTION
197 select HAVE_KRETPROBES
199 select HAVE_LIVEPATCH if X86_64
200 select HAVE_MIXED_BREAKPOINTS_REGS
201 select HAVE_MOD_ARCH_SPECIFIC
205 select HAVE_OPTPROBES
206 select HAVE_PCSPKR_PLATFORM
207 select HAVE_PERF_EVENTS
208 select HAVE_PERF_EVENTS_NMI
209 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
211 select HAVE_PERF_REGS
212 select HAVE_PERF_USER_STACK_DUMP
213 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
214 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
215 select HAVE_REGS_AND_STACK_ACCESS_API
216 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
217 select HAVE_FUNCTION_ARG_ACCESS_API
218 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
219 select HAVE_STACK_VALIDATION if X86_64
220 select HAVE_STATIC_CALL
221 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
223 select HAVE_SYSCALL_TRACEPOINTS
224 select HAVE_UNSTABLE_SCHED_CLOCK
225 select HAVE_USER_RETURN_NOTIFIER
226 select HAVE_GENERIC_VDSO
227 select HOTPLUG_SMT if SMP
228 select IRQ_FORCED_THREADING
229 select NEED_SG_DMA_LENGTH
230 select PCI_DOMAINS if PCI
231 select PCI_LOCKLESS_CONFIG if PCI
234 select RTC_MC146818_LIB
237 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
238 select SYSCTL_EXCEPTION_TRACE
239 select THREAD_INFO_IN_TASK
240 select USER_STACKTRACE_SUPPORT
242 select HAVE_ARCH_KCSAN if X86_64
243 select X86_FEATURE_NAMES if PROC_FS
244 select PROC_PID_ARCH_STATUS if PROC_FS
245 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
247 config INSTRUCTION_DECODER
249 depends on KPROBES || PERF_EVENTS || UPROBES
253 default "elf32-i386" if X86_32
254 default "elf64-x86-64" if X86_64
256 config LOCKDEP_SUPPORT
259 config STACKTRACE_SUPPORT
265 config ARCH_MMAP_RND_BITS_MIN
269 config ARCH_MMAP_RND_BITS_MAX
273 config ARCH_MMAP_RND_COMPAT_BITS_MIN
276 config ARCH_MMAP_RND_COMPAT_BITS_MAX
282 config GENERIC_ISA_DMA
284 depends on ISA_DMA_API
289 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
291 config GENERIC_BUG_RELATIVE_POINTERS
294 config ARCH_MAY_HAVE_PC_FDC
296 depends on ISA_DMA_API
298 config GENERIC_CALIBRATE_DELAY
301 config ARCH_HAS_CPU_RELAX
304 config ARCH_HAS_CACHE_LINE_SIZE
307 config ARCH_HAS_FILTER_PGPROT
310 config HAVE_SETUP_PER_CPU_AREA
313 config NEED_PER_CPU_EMBED_FIRST_CHUNK
316 config NEED_PER_CPU_PAGE_FIRST_CHUNK
319 config ARCH_HIBERNATION_POSSIBLE
322 config ARCH_SUSPEND_POSSIBLE
325 config ARCH_WANT_GENERAL_HUGETLB
334 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
337 config KASAN_SHADOW_OFFSET
340 default 0xdffffc0000000000
342 config HAVE_INTEL_TXT
344 depends on INTEL_IOMMU && ACPI
348 depends on X86_32 && SMP
352 depends on X86_64 && SMP
354 config X86_32_LAZY_GS
356 depends on X86_32 && !STACKPROTECTOR
358 config ARCH_SUPPORTS_UPROBES
361 config FIX_EARLYCON_MEM
364 config DYNAMIC_PHYSICAL_MASK
367 config PGTABLE_LEVELS
369 default 5 if X86_5LEVEL
374 config CC_HAS_SANE_STACKPROTECTOR
376 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
377 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
379 We have to make sure stack protector is unconditionally disabled if
380 the compiler produces broken code.
382 menu "Processor type and features"
385 bool "DMA memory allocation support" if EXPERT
388 DMA memory allocation support allows devices with less than 32-bit
389 addressing to allocate within the first 16MB of address space.
390 Disable if no such devices will be used.
395 bool "Symmetric multi-processing support"
397 This enables support for systems with more than one CPU. If you have
398 a system with only one CPU, say N. If you have a system with more
401 If you say N here, the kernel will run on uni- and multiprocessor
402 machines, but will use only one CPU of a multiprocessor machine. If
403 you say Y here, the kernel will run on many, but not all,
404 uniprocessor machines. On a uniprocessor machine, the kernel
405 will run faster if you say N here.
407 Note that if you say Y here and choose architecture "586" or
408 "Pentium" under "Processor family", the kernel will not work on 486
409 architectures. Similarly, multiprocessor kernels for the "PPro"
410 architecture may not work on all Pentium based boards.
412 People using multiprocessor machines who say Y here should also say
413 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
414 Management" code will be disabled if you say Y here.
416 See also <file:Documentation/x86/i386/IO-APIC.rst>,
417 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
418 <http://www.tldp.org/docs.html#howto>.
420 If you don't know what to do here, say N.
422 config X86_FEATURE_NAMES
423 bool "Processor feature human-readable names" if EMBEDDED
426 This option compiles in a table of x86 feature bits and corresponding
427 names. This is required to support /proc/cpuinfo and a few kernel
428 messages. You can disable this to save space, at the expense of
429 making those few kernel messages show numeric feature bits instead.
434 bool "Support x2apic"
435 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
437 This enables x2apic support on CPUs that have this feature.
439 This allows 32-bit apic IDs (so it can support very large systems),
440 and accesses the local apic via MSRs not via mmio.
442 If you don't know what to do here, say N.
445 bool "Enable MPS table" if ACPI || SFI
447 depends on X86_LOCAL_APIC
449 For old smp systems that do not have proper acpi support. Newer systems
450 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
454 depends on X86_GOLDFISH
457 bool "Avoid speculative indirect branches in kernel"
460 Compile kernel with the retpoline compiler options to guard against
461 kernel-to-user data leaks by avoiding speculative indirect
462 branches. Requires a compiler with -mindirect-branch=thunk-extern
463 support for full protection. The kernel may run slower.
465 config X86_CPU_RESCTRL
466 bool "x86 CPU resource control support"
467 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
469 select PROC_CPU_RESCTRL if PROC_FS
471 Enable x86 CPU resource control support.
473 Provide support for the allocation and monitoring of system resources
476 Intel calls this Intel Resource Director Technology
477 (Intel(R) RDT). More information about RDT can be found in the
478 Intel x86 Architecture Software Developer Manual.
480 AMD calls this AMD Platform Quality of Service (AMD QoS).
481 More information about AMD QoS can be found in the AMD64 Technology
482 Platform Quality of Service Extensions manual.
488 bool "Support for big SMP systems with more than 8 CPUs"
491 This option is needed for the systems that have more than 8 CPUs.
493 config X86_EXTENDED_PLATFORM
494 bool "Support for extended (non-PC) x86 platforms"
497 If you disable this option then the kernel will only support
498 standard PC platforms. (which covers the vast majority of
501 If you enable this option then you'll be able to select support
502 for the following (non-PC) 32 bit x86 platforms:
503 Goldfish (Android emulator)
506 SGI 320/540 (Visual Workstation)
507 STA2X11-based (e.g. Northville)
508 Moorestown MID devices
510 If you have one of these systems, or if you want to build a
511 generic distribution kernel, say Y here - otherwise say N.
515 config X86_EXTENDED_PLATFORM
516 bool "Support for extended (non-PC) x86 platforms"
519 If you disable this option then the kernel will only support
520 standard PC platforms. (which covers the vast majority of
523 If you enable this option then you'll be able to select support
524 for the following (non-PC) 64 bit x86 platforms:
529 If you have one of these systems, or if you want to build a
530 generic distribution kernel, say Y here - otherwise say N.
532 # This is an alphabetically sorted list of 64 bit extended platforms
533 # Please maintain the alphabetic order if and when there are additions
535 bool "Numascale NumaChip"
537 depends on X86_EXTENDED_PLATFORM
540 depends on X86_X2APIC
541 depends on PCI_MMCONFIG
543 Adds support for Numascale NumaChip large-SMP systems. Needed to
544 enable more than ~168 cores.
545 If you don't have one of these, you should say N here.
549 select HYPERVISOR_GUEST
551 depends on X86_64 && PCI
552 depends on X86_EXTENDED_PLATFORM
555 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
556 supposed to run on these EM64T-based machines. Only choose this option
557 if you have one of these machines.
560 bool "SGI Ultraviolet"
562 depends on X86_EXTENDED_PLATFORM
565 depends on X86_X2APIC
568 This option is needed in order to support SGI Ultraviolet systems.
569 If you don't have one of these, you should say N here.
571 # Following is an alphabetically sorted list of 32 bit extended platforms
572 # Please maintain the alphabetic order if and when there are additions
575 bool "Goldfish (Virtual Platform)"
576 depends on X86_EXTENDED_PLATFORM
578 Enable support for the Goldfish virtual platform used primarily
579 for Android development. Unless you are building for the Android
580 Goldfish emulator say N here.
583 bool "CE4100 TV platform"
585 depends on PCI_GODIRECT
586 depends on X86_IO_APIC
588 depends on X86_EXTENDED_PLATFORM
589 select X86_REBOOTFIXUPS
591 select OF_EARLY_FLATTREE
593 Select for the Intel CE media processor (CE4100) SOC.
594 This option compiles in support for the CE4100 SOC for settop
595 boxes and media devices.
598 bool "Intel MID platform support"
599 depends on X86_EXTENDED_PLATFORM
600 depends on X86_PLATFORM_DEVICES
602 depends on X86_64 || (PCI_GOANY && X86_32)
603 depends on X86_IO_APIC
609 select MFD_INTEL_MSIC
611 Select to build a kernel capable of supporting Intel MID (Mobile
612 Internet Device) platform systems which do not have the PCI legacy
613 interfaces. If you are building for a PC class system say N here.
615 Intel MID platforms are based on an Intel processor and chipset which
616 consume less power than most of the x86 derivatives.
618 config X86_INTEL_QUARK
619 bool "Intel Quark platform support"
621 depends on X86_EXTENDED_PLATFORM
622 depends on X86_PLATFORM_DEVICES
626 depends on X86_IO_APIC
631 Select to include support for Quark X1000 SoC.
632 Say Y here if you have a Quark based system such as the Arduino
633 compatible Intel Galileo.
635 config X86_INTEL_LPSS
636 bool "Intel Low Power Subsystem Support"
637 depends on X86 && ACPI && PCI
642 Select to build support for Intel Low Power Subsystem such as
643 found on Intel Lynxpoint PCH. Selecting this option enables
644 things like clock tree (common clock framework) and pincontrol
645 which are needed by the LPSS peripheral drivers.
647 config X86_AMD_PLATFORM_DEVICE
648 bool "AMD ACPI2Platform devices support"
653 Select to interpret AMD specific ACPI device to platform device
654 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
655 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
656 implemented under PINCTRL subsystem.
659 tristate "Intel SoC IOSF Sideband support for SoC platforms"
662 This option enables sideband register access support for Intel SoC
663 platforms. On these platforms the IOSF sideband is used in lieu of
664 MSR's for some register accesses, mostly but not limited to thermal
665 and power. Drivers may query the availability of this device to
666 determine if they need the sideband in order to work on these
667 platforms. The sideband is available on the following SoC products.
668 This list is not meant to be exclusive.
673 You should say Y if you are running a kernel on one of these SoC's.
675 config IOSF_MBI_DEBUG
676 bool "Enable IOSF sideband access through debugfs"
677 depends on IOSF_MBI && DEBUG_FS
679 Select this option to expose the IOSF sideband access registers (MCR,
680 MDR, MCRX) through debugfs to write and read register information from
681 different units on the SoC. This is most useful for obtaining device
682 state information for debug and analysis. As this is a general access
683 mechanism, users of this option would have specific knowledge of the
684 device they want to access.
686 If you don't require the option or are in doubt, say N.
689 bool "RDC R-321x SoC"
691 depends on X86_EXTENDED_PLATFORM
693 select X86_REBOOTFIXUPS
695 This option is needed for RDC R-321x system-on-chip, also known
697 If you don't have one of these chips, you should say N here.
699 config X86_32_NON_STANDARD
700 bool "Support non-standard 32-bit SMP architectures"
701 depends on X86_32 && SMP
702 depends on X86_EXTENDED_PLATFORM
704 This option compiles in the bigsmp and STA2X11 default
705 subarchitectures. It is intended for a generic binary
706 kernel. If you select them all, kernel will probe it one by
707 one and will fallback to default.
709 # Alphabetically sorted list of Non standard 32 bit platforms
711 config X86_SUPPORTS_MEMORY_FAILURE
713 # MCE code calls memory_failure():
715 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
716 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
717 depends on X86_64 || !SPARSEMEM
718 select ARCH_SUPPORTS_MEMORY_FAILURE
721 bool "STA2X11 Companion Chip Support"
722 depends on X86_32_NON_STANDARD && PCI
727 This adds support for boards based on the STA2X11 IO-Hub,
728 a.k.a. "ConneXt". The chip is used in place of the standard
729 PC chipset, so all "standard" peripherals are missing. If this
730 option is selected the kernel will still be able to boot on
731 standard PC machines.
734 tristate "Eurobraille/Iris poweroff module"
737 The Iris machines from EuroBraille do not have APM or ACPI support
738 to shut themselves down properly. A special I/O sequence is
739 needed to do so, which is what this module does at
742 This is only for Iris machines from EuroBraille.
746 config SCHED_OMIT_FRAME_POINTER
748 prompt "Single-depth WCHAN output"
751 Calculate simpler /proc/<PID>/wchan values. If this option
752 is disabled then wchan values will recurse back to the
753 caller function. This provides more accurate wchan values,
754 at the expense of slightly more scheduling overhead.
756 If in doubt, say "Y".
758 menuconfig HYPERVISOR_GUEST
759 bool "Linux guest support"
761 Say Y here to enable options for running Linux under various hyper-
762 visors. This option enables basic hypervisor detection and platform
765 If you say N, all options in this submenu will be skipped and
766 disabled, and Linux guest support won't be built in.
771 bool "Enable paravirtualization code"
773 This changes the kernel so it can modify itself when it is run
774 under a hypervisor, potentially improving performance significantly
775 over full virtualization. However, when run without a hypervisor
776 the kernel is theoretically slower and slightly larger.
781 config PARAVIRT_DEBUG
782 bool "paravirt-ops debugging"
783 depends on PARAVIRT && DEBUG_KERNEL
785 Enable to debug paravirt_ops internals. Specifically, BUG if
786 a paravirt_op is missing when it is called.
788 config PARAVIRT_SPINLOCKS
789 bool "Paravirtualization layer for spinlocks"
790 depends on PARAVIRT && SMP
792 Paravirtualized spinlocks allow a pvops backend to replace the
793 spinlock implementation with something virtualization-friendly
794 (for example, block the virtual CPU rather than spinning).
796 It has a minimal impact on native kernels and gives a nice performance
797 benefit on paravirtualized KVM / Xen kernels.
799 If you are unsure how to answer this question, answer Y.
801 config X86_HV_CALLBACK_VECTOR
804 source "arch/x86/xen/Kconfig"
807 bool "KVM Guest support (including kvmclock)"
809 select PARAVIRT_CLOCK
810 select ARCH_CPUIDLE_HALTPOLL
811 select X86_HV_CALLBACK_VECTOR
814 This option enables various optimizations for running under the KVM
815 hypervisor. It includes a paravirtualized clock, so that instead
816 of relying on a PIT (or probably other) emulation by the
817 underlying device model, the host provides the guest with
818 timing infrastructure such as time of day, and system time
820 config ARCH_CPUIDLE_HALTPOLL
822 prompt "Disable host haltpoll when loading haltpoll driver"
824 If virtualized under KVM, disable host haltpoll.
827 bool "Support for running PVH guests"
829 This option enables the PVH entry point for guest virtual machines
830 as specified in the x86/HVM direct boot ABI.
832 config PARAVIRT_TIME_ACCOUNTING
833 bool "Paravirtual steal time accounting"
836 Select this option to enable fine granularity task steal time
837 accounting. Time spent executing other tasks in parallel with
838 the current vCPU is discounted from the vCPU power. To account for
839 that, there can be a small performance impact.
841 If in doubt, say N here.
843 config PARAVIRT_CLOCK
846 config JAILHOUSE_GUEST
847 bool "Jailhouse non-root cell support"
848 depends on X86_64 && PCI
851 This option allows to run Linux as guest in a Jailhouse non-root
852 cell. You can leave this option disabled if you only want to start
853 Jailhouse and run Linux afterwards in the root cell.
856 bool "ACRN Guest support"
858 select X86_HV_CALLBACK_VECTOR
860 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
861 a flexible, lightweight reference open-source hypervisor, built with
862 real-time and safety-criticality in mind. It is built for embedded
863 IOT with small footprint and real-time features. More details can be
864 found in https://projectacrn.org/.
866 endif #HYPERVISOR_GUEST
868 source "arch/x86/Kconfig.cpu"
872 prompt "HPET Timer Support" if X86_32
874 Use the IA-PC HPET (High Precision Event Timer) to manage
875 time in preference to the PIT and RTC, if a HPET is
877 HPET is the next generation timer replacing legacy 8254s.
878 The HPET provides a stable time base on SMP
879 systems, unlike the TSC, but it is more expensive to access,
880 as it is off-chip. The interface used is documented
881 in the HPET spec, revision 1.
883 You can safely choose Y here. However, HPET will only be
884 activated if the platform and the BIOS support this feature.
885 Otherwise the 8254 will be used for timing services.
887 Choose N to continue using the legacy 8254 timer.
889 config HPET_EMULATE_RTC
891 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
894 def_bool y if X86_INTEL_MID
895 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
897 depends on X86_INTEL_MID && SFI
899 APB timer is the replacement for 8254, HPET on X86 MID platforms.
900 The APBT provides a stable time base on SMP
901 systems, unlike the TSC, but it is more expensive to access,
902 as it is off-chip. APB timers are always running regardless of CPU
903 C states, they are used as per CPU clockevent device when possible.
905 # Mark as expert because too many people got it wrong.
906 # The code disables itself when not needed.
909 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
910 bool "Enable DMI scanning" if EXPERT
912 Enabled scanning of DMI to identify machine quirks. Say Y
913 here unless you have verified that your setup is not
914 affected by entries in the DMI blacklist. Required by PNP
918 bool "Old AMD GART IOMMU support"
922 depends on X86_64 && PCI && AMD_NB
924 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
925 GART based hardware IOMMUs.
927 The GART supports full DMA access for devices with 32-bit access
928 limitations, on systems with more than 3 GB. This is usually needed
929 for USB, sound, many IDE/SATA chipsets and some other devices.
931 Newer systems typically have a modern AMD IOMMU, supported via
932 the CONFIG_AMD_IOMMU=y config option.
934 In normal configurations this driver is only active when needed:
935 there's more than 3 GB of memory and the system contains a
936 32-bit limited device.
941 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
942 depends on X86_64 && SMP && DEBUG_KERNEL
943 select CPUMASK_OFFSTACK
945 Enable maximum number of CPUS and NUMA Nodes for this architecture.
949 # The maximum number of CPUs supported:
951 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
952 # and which can be configured interactively in the
953 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
955 # The ranges are different on 32-bit and 64-bit kernels, depending on
956 # hardware capabilities and scalability features of the kernel.
958 # ( If MAXSMP is enabled we just use the highest possible value and disable
959 # interactive configuration. )
962 config NR_CPUS_RANGE_BEGIN
964 default NR_CPUS_RANGE_END if MAXSMP
968 config NR_CPUS_RANGE_END
971 default 64 if SMP && X86_BIGSMP
972 default 8 if SMP && !X86_BIGSMP
975 config NR_CPUS_RANGE_END
978 default 8192 if SMP && CPUMASK_OFFSTACK
979 default 512 if SMP && !CPUMASK_OFFSTACK
982 config NR_CPUS_DEFAULT
985 default 32 if X86_BIGSMP
989 config NR_CPUS_DEFAULT
992 default 8192 if MAXSMP
997 int "Maximum number of CPUs" if SMP && !MAXSMP
998 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
999 default NR_CPUS_DEFAULT
1001 This allows you to specify the maximum number of CPUs which this
1002 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1003 supported value is 8192, otherwise the maximum value is 512. The
1004 minimum value which makes sense is 2.
1006 This is purely to save memory: each supported CPU adds about 8KB
1007 to the kernel image.
1014 prompt "Multi-core scheduler support"
1017 Multi-core scheduler support improves the CPU scheduler's decision
1018 making when dealing with multi-core CPU chips at a cost of slightly
1019 increased overhead in some places. If unsure say N here.
1021 config SCHED_MC_PRIO
1022 bool "CPU core priorities scheduler support"
1023 depends on SCHED_MC && CPU_SUP_INTEL
1024 select X86_INTEL_PSTATE
1028 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1029 core ordering determined at manufacturing time, which allows
1030 certain cores to reach higher turbo frequencies (when running
1031 single threaded workloads) than others.
1033 Enabling this kernel feature teaches the scheduler about
1034 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1035 scheduler's CPU selection logic accordingly, so that higher
1036 overall system performance can be achieved.
1038 This feature will have no effect on CPUs without this feature.
1040 If unsure say Y here.
1044 depends on !SMP && X86_LOCAL_APIC
1047 bool "Local APIC support on uniprocessors" if !PCI_MSI
1049 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1051 A local APIC (Advanced Programmable Interrupt Controller) is an
1052 integrated interrupt controller in the CPU. If you have a single-CPU
1053 system which has a processor with a local APIC, you can say Y here to
1054 enable and use it. If you say Y here even though your machine doesn't
1055 have a local APIC, then the kernel will still run with no slowdown at
1056 all. The local APIC supports CPU-generated self-interrupts (timer,
1057 performance counters), and the NMI watchdog which detects hard
1060 config X86_UP_IOAPIC
1061 bool "IO-APIC support on uniprocessors"
1062 depends on X86_UP_APIC
1064 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1065 SMP-capable replacement for PC-style interrupt controllers. Most
1066 SMP systems and many recent uniprocessor systems have one.
1068 If you have a single-CPU system with an IO-APIC, you can say Y here
1069 to use it. If you say Y here even though your machine doesn't have
1070 an IO-APIC, then the kernel will still run with no slowdown at all.
1072 config X86_LOCAL_APIC
1074 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1075 select IRQ_DOMAIN_HIERARCHY
1076 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1080 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1082 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1083 bool "Reroute for broken boot IRQs"
1084 depends on X86_IO_APIC
1086 This option enables a workaround that fixes a source of
1087 spurious interrupts. This is recommended when threaded
1088 interrupt handling is used on systems where the generation of
1089 superfluous "boot interrupts" cannot be disabled.
1091 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1092 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1093 kernel does during interrupt handling). On chipsets where this
1094 boot IRQ generation cannot be disabled, this workaround keeps
1095 the original IRQ line masked so that only the equivalent "boot
1096 IRQ" is delivered to the CPUs. The workaround also tells the
1097 kernel to set up the IRQ handler on the boot IRQ line. In this
1098 way only one interrupt is delivered to the kernel. Otherwise
1099 the spurious second interrupt may cause the kernel to bring
1100 down (vital) interrupt lines.
1102 Only affects "broken" chipsets. Interrupt sharing may be
1103 increased on these systems.
1106 bool "Machine Check / overheating reporting"
1107 select GENERIC_ALLOCATOR
1110 Machine Check support allows the processor to notify the
1111 kernel if it detects a problem (e.g. overheating, data corruption).
1112 The action the kernel takes depends on the severity of the problem,
1113 ranging from warning messages to halting the machine.
1115 config X86_MCELOG_LEGACY
1116 bool "Support for deprecated /dev/mcelog character device"
1119 Enable support for /dev/mcelog which is needed by the old mcelog
1120 userspace logging daemon. Consider switching to the new generation
1123 config X86_MCE_INTEL
1125 prompt "Intel MCE features"
1126 depends on X86_MCE && X86_LOCAL_APIC
1128 Additional support for intel specific MCE features such as
1129 the thermal monitor.
1133 prompt "AMD MCE features"
1134 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1136 Additional support for AMD specific MCE features such as
1137 the DRAM Error Threshold.
1139 config X86_ANCIENT_MCE
1140 bool "Support for old Pentium 5 / WinChip machine checks"
1141 depends on X86_32 && X86_MCE
1143 Include support for machine check handling on old Pentium 5 or WinChip
1144 systems. These typically need to be enabled explicitly on the command
1147 config X86_MCE_THRESHOLD
1148 depends on X86_MCE_AMD || X86_MCE_INTEL
1151 config X86_MCE_INJECT
1152 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1153 tristate "Machine check injector support"
1155 Provide support for injecting machine checks for testing purposes.
1156 If you don't know what a machine check is and you don't do kernel
1157 QA it is safe to say n.
1159 config X86_THERMAL_VECTOR
1161 depends on X86_MCE_INTEL
1163 source "arch/x86/events/Kconfig"
1165 config X86_LEGACY_VM86
1166 bool "Legacy VM86 support"
1169 This option allows user programs to put the CPU into V8086
1170 mode, which is an 80286-era approximation of 16-bit real mode.
1172 Some very old versions of X and/or vbetool require this option
1173 for user mode setting. Similarly, DOSEMU will use it if
1174 available to accelerate real mode DOS programs. However, any
1175 recent version of DOSEMU, X, or vbetool should be fully
1176 functional even without kernel VM86 support, as they will all
1177 fall back to software emulation. Nevertheless, if you are using
1178 a 16-bit DOS program where 16-bit performance matters, vm86
1179 mode might be faster than emulation and you might want to
1182 Note that any app that works on a 64-bit kernel is unlikely to
1183 need this option, as 64-bit kernels don't, and can't, support
1184 V8086 mode. This option is also unrelated to 16-bit protected
1185 mode and is not needed to run most 16-bit programs under Wine.
1187 Enabling this option increases the complexity of the kernel
1188 and slows down exception handling a tiny bit.
1190 If unsure, say N here.
1194 default X86_LEGACY_VM86
1197 bool "Enable support for 16-bit segments" if EXPERT
1199 depends on MODIFY_LDT_SYSCALL
1201 This option is required by programs like Wine to run 16-bit
1202 protected mode legacy code on x86 processors. Disabling
1203 this option saves about 300 bytes on i386, or around 6K text
1204 plus 16K runtime memory on x86-64,
1208 depends on X86_16BIT && X86_32
1212 depends on X86_16BIT && X86_64
1214 config X86_VSYSCALL_EMULATION
1215 bool "Enable vsyscall emulation" if EXPERT
1219 This enables emulation of the legacy vsyscall page. Disabling
1220 it is roughly equivalent to booting with vsyscall=none, except
1221 that it will also disable the helpful warning if a program
1222 tries to use a vsyscall. With this option set to N, offending
1223 programs will just segfault, citing addresses of the form
1226 This option is required by many programs built before 2013, and
1227 care should be used even with newer programs if set to N.
1229 Disabling this option saves about 7K of kernel size and
1230 possibly 4K of additional runtime pagetable memory.
1232 config X86_IOPL_IOPERM
1233 bool "IOPERM and IOPL Emulation"
1236 This enables the ioperm() and iopl() syscalls which are necessary
1237 for legacy applications.
1239 Legacy IOPL support is an overbroad mechanism which allows user
1240 space aside of accessing all 65536 I/O ports also to disable
1241 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1242 capabilities and permission from potentially active security
1245 The emulation restricts the functionality of the syscall to
1246 only allowing the full range I/O port access, but prevents the
1247 ability to disable interrupts from user space which would be
1248 granted if the hardware IOPL mechanism would be used.
1251 tristate "Toshiba Laptop support"
1254 This adds a driver to safely access the System Management Mode of
1255 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1256 not work on models with a Phoenix BIOS. The System Management Mode
1257 is used to set the BIOS and power saving options on Toshiba portables.
1259 For information on utilities to make use of this driver see the
1260 Toshiba Linux utilities web site at:
1261 <http://www.buzzard.org.uk/toshiba/>.
1263 Say Y if you intend to run this kernel on a Toshiba portable.
1267 tristate "Dell i8k legacy laptop support"
1269 select SENSORS_DELL_SMM
1271 This option enables legacy /proc/i8k userspace interface in hwmon
1272 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1273 temperature and allows controlling fan speeds of Dell laptops via
1274 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1275 it reports also power and hotkey status. For fan speed control is
1276 needed userspace package i8kutils.
1278 Say Y if you intend to run this kernel on old Dell laptops or want to
1279 use userspace package i8kutils.
1282 config X86_REBOOTFIXUPS
1283 bool "Enable X86 board specific fixups for reboot"
1286 This enables chipset and/or board specific fixups to be done
1287 in order to get reboot to work correctly. This is only needed on
1288 some combinations of hardware and BIOS. The symptom, for which
1289 this config is intended, is when reboot ends with a stalled/hung
1292 Currently, the only fixup is for the Geode machines using
1293 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1295 Say Y if you want to enable the fixup. Currently, it's safe to
1296 enable this option even if you don't need it.
1300 bool "CPU microcode loading support"
1302 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1304 If you say Y here, you will be able to update the microcode on
1305 Intel and AMD processors. The Intel support is for the IA32 family,
1306 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1307 AMD support is for families 0x10 and later. You will obviously need
1308 the actual microcode binary data itself which is not shipped with
1311 The preferred method to load microcode from a detached initrd is described
1312 in Documentation/x86/microcode.rst. For that you need to enable
1313 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1314 initrd for microcode blobs.
1316 In addition, you can build the microcode into the kernel. For that you
1317 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1320 config MICROCODE_INTEL
1321 bool "Intel microcode loading support"
1322 depends on MICROCODE
1325 This options enables microcode patch loading support for Intel
1328 For the current Intel microcode data package go to
1329 <https://downloadcenter.intel.com> and search for
1330 'Linux Processor Microcode Data File'.
1332 config MICROCODE_AMD
1333 bool "AMD microcode loading support"
1334 depends on MICROCODE
1336 If you select this option, microcode patch loading support for AMD
1337 processors will be enabled.
1339 config MICROCODE_OLD_INTERFACE
1340 bool "Ancient loading interface (DEPRECATED)"
1342 depends on MICROCODE
1344 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1345 which was used by userspace tools like iucode_tool and microcode.ctl.
1346 It is inadequate because it runs too late to be able to properly
1347 load microcode on a machine and it needs special tools. Instead, you
1348 should've switched to the early loading method with the initrd or
1349 builtin microcode by now: Documentation/x86/microcode.rst
1352 tristate "/dev/cpu/*/msr - Model-specific register support"
1354 This device gives privileged processes access to the x86
1355 Model-Specific Registers (MSRs). It is a character device with
1356 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1357 MSR accesses are directed to a specific CPU on multi-processor
1361 tristate "/dev/cpu/*/cpuid - CPU information support"
1363 This device gives processes access to the x86 CPUID instruction to
1364 be executed on a specific processor. It is a character device
1365 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1369 prompt "High Memory Support"
1376 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1377 However, the address space of 32-bit x86 processors is only 4
1378 Gigabytes large. That means that, if you have a large amount of
1379 physical memory, not all of it can be "permanently mapped" by the
1380 kernel. The physical memory that's not permanently mapped is called
1383 If you are compiling a kernel which will never run on a machine with
1384 more than 1 Gigabyte total physical RAM, answer "off" here (default
1385 choice and suitable for most users). This will result in a "3GB/1GB"
1386 split: 3GB are mapped so that each process sees a 3GB virtual memory
1387 space and the remaining part of the 4GB virtual memory space is used
1388 by the kernel to permanently map as much physical memory as
1391 If the machine has between 1 and 4 Gigabytes physical RAM, then
1394 If more than 4 Gigabytes is used then answer "64GB" here. This
1395 selection turns Intel PAE (Physical Address Extension) mode on.
1396 PAE implements 3-level paging on IA32 processors. PAE is fully
1397 supported by Linux, PAE mode is implemented on all recent Intel
1398 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1399 then the kernel will not boot on CPUs that don't support PAE!
1401 The actual amount of total physical memory will either be
1402 auto detected or can be forced by using a kernel command line option
1403 such as "mem=256M". (Try "man bootparam" or see the documentation of
1404 your boot loader (lilo or loadlin) about how to pass options to the
1405 kernel at boot time.)
1407 If unsure, say "off".
1412 Select this if you have a 32-bit processor and between 1 and 4
1413 gigabytes of physical RAM.
1417 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1420 Select this if you have a 32-bit processor and more than 4
1421 gigabytes of physical RAM.
1426 prompt "Memory split" if EXPERT
1430 Select the desired split between kernel and user memory.
1432 If the address range available to the kernel is less than the
1433 physical memory installed, the remaining memory will be available
1434 as "high memory". Accessing high memory is a little more costly
1435 than low memory, as it needs to be mapped into the kernel first.
1436 Note that increasing the kernel address space limits the range
1437 available to user programs, making the address space there
1438 tighter. Selecting anything other than the default 3G/1G split
1439 will also likely make your kernel incompatible with binary-only
1442 If you are not absolutely sure what you are doing, leave this
1446 bool "3G/1G user/kernel split"
1447 config VMSPLIT_3G_OPT
1449 bool "3G/1G user/kernel split (for full 1G low memory)"
1451 bool "2G/2G user/kernel split"
1452 config VMSPLIT_2G_OPT
1454 bool "2G/2G user/kernel split (for full 2G low memory)"
1456 bool "1G/3G user/kernel split"
1461 default 0xB0000000 if VMSPLIT_3G_OPT
1462 default 0x80000000 if VMSPLIT_2G
1463 default 0x78000000 if VMSPLIT_2G_OPT
1464 default 0x40000000 if VMSPLIT_1G
1470 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1473 bool "PAE (Physical Address Extension) Support"
1474 depends on X86_32 && !HIGHMEM4G
1475 select PHYS_ADDR_T_64BIT
1478 PAE is required for NX support, and furthermore enables
1479 larger swapspace support for non-overcommit purposes. It
1480 has the cost of more pagetable lookup overhead, and also
1481 consumes more pagetable space per process.
1484 bool "Enable 5-level page tables support"
1486 select DYNAMIC_MEMORY_LAYOUT
1487 select SPARSEMEM_VMEMMAP
1490 5-level paging enables access to larger address space:
1491 upto 128 PiB of virtual address space and 4 PiB of
1492 physical address space.
1494 It will be supported by future Intel CPUs.
1496 A kernel with the option enabled can be booted on machines that
1497 support 4- or 5-level paging.
1499 See Documentation/x86/x86_64/5level-paging.rst for more
1504 config X86_DIRECT_GBPAGES
1508 Certain kernel features effectively disable kernel
1509 linear 1 GB mappings (even if the CPU otherwise
1510 supports them), so don't confuse the user by printing
1511 that we have them enabled.
1513 config X86_CPA_STATISTICS
1514 bool "Enable statistic for Change Page Attribute"
1517 Expose statistics about the Change Page Attribute mechanism, which
1518 helps to determine the effectiveness of preserving large and huge
1519 page mappings when mapping protections are changed.
1521 config AMD_MEM_ENCRYPT
1522 bool "AMD Secure Memory Encryption (SME) support"
1523 depends on X86_64 && CPU_SUP_AMD
1524 select DMA_COHERENT_POOL
1525 select DYNAMIC_PHYSICAL_MASK
1526 select ARCH_USE_MEMREMAP_PROT
1527 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1528 select INSTRUCTION_DECODER
1530 Say yes to enable support for the encryption of system memory.
1531 This requires an AMD processor that supports Secure Memory
1534 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1535 bool "Activate AMD Secure Memory Encryption (SME) by default"
1537 depends on AMD_MEM_ENCRYPT
1539 Say yes to have system memory encrypted by default if running on
1540 an AMD processor that supports Secure Memory Encryption (SME).
1542 If set to Y, then the encryption of system memory can be
1543 deactivated with the mem_encrypt=off command line option.
1545 If set to N, then the encryption of system memory can be
1546 activated with the mem_encrypt=on command line option.
1548 # Common NUMA Features
1550 bool "NUMA Memory Allocation and Scheduler Support"
1552 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1553 default y if X86_BIGSMP
1555 Enable NUMA (Non-Uniform Memory Access) support.
1557 The kernel will try to allocate memory used by a CPU on the
1558 local memory controller of the CPU and add some more
1559 NUMA awareness to the kernel.
1561 For 64-bit this is recommended if the system is Intel Core i7
1562 (or later), AMD Opteron, or EM64T NUMA.
1564 For 32-bit this is only needed if you boot a 32-bit
1565 kernel on a 64-bit NUMA platform.
1567 Otherwise, you should say N.
1571 prompt "Old style AMD Opteron NUMA detection"
1572 depends on X86_64 && NUMA && PCI
1574 Enable AMD NUMA node topology detection. You should say Y here if
1575 you have a multi processor AMD system. This uses an old method to
1576 read the NUMA configuration directly from the builtin Northbridge
1577 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1578 which also takes priority if both are compiled in.
1580 config X86_64_ACPI_NUMA
1582 prompt "ACPI NUMA detection"
1583 depends on X86_64 && NUMA && ACPI && PCI
1586 Enable ACPI SRAT based node topology detection.
1589 bool "NUMA emulation"
1592 Enable NUMA emulation. A flat machine will be split
1593 into virtual nodes when booted with "numa=fake=N", where N is the
1594 number of nodes. This is only useful for debugging.
1597 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1599 default "10" if MAXSMP
1600 default "6" if X86_64
1602 depends on NEED_MULTIPLE_NODES
1604 Specify the maximum number of NUMA Nodes available on the target
1605 system. Increases memory reserved to accommodate various tables.
1607 config ARCH_FLATMEM_ENABLE
1609 depends on X86_32 && !NUMA
1611 config ARCH_SPARSEMEM_ENABLE
1613 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1614 select SPARSEMEM_STATIC if X86_32
1615 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1617 config ARCH_SPARSEMEM_DEFAULT
1618 def_bool X86_64 || (NUMA && X86_32)
1620 config ARCH_SELECT_MEMORY_MODEL
1622 depends on ARCH_SPARSEMEM_ENABLE
1624 config ARCH_MEMORY_PROBE
1625 bool "Enable sysfs memory/probe interface"
1626 depends on X86_64 && MEMORY_HOTPLUG
1628 This option enables a sysfs memory/probe interface for testing.
1629 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1630 If you are unsure how to answer this question, answer N.
1632 config ARCH_PROC_KCORE_TEXT
1634 depends on X86_64 && PROC_KCORE
1636 config ILLEGAL_POINTER_VALUE
1639 default 0xdead000000000000 if X86_64
1641 config X86_PMEM_LEGACY_DEVICE
1644 config X86_PMEM_LEGACY
1645 tristate "Support non-standard NVDIMMs and ADR protected memory"
1646 depends on PHYS_ADDR_T_64BIT
1648 select X86_PMEM_LEGACY_DEVICE
1649 select NUMA_KEEP_MEMINFO if NUMA
1652 Treat memory marked using the non-standard e820 type of 12 as used
1653 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1654 The kernel will offer these regions to the 'pmem' driver so
1655 they can be used for persistent storage.
1660 bool "Allocate 3rd-level pagetables from highmem"
1663 The VM uses one page table entry for each page of physical memory.
1664 For systems with a lot of RAM, this can be wasteful of precious
1665 low memory. Setting this option will put user-space page table
1666 entries in high memory.
1668 config X86_CHECK_BIOS_CORRUPTION
1669 bool "Check for low memory corruption"
1671 Periodically check for memory corruption in low memory, which
1672 is suspected to be caused by BIOS. Even when enabled in the
1673 configuration, it is disabled at runtime. Enable it by
1674 setting "memory_corruption_check=1" on the kernel command
1675 line. By default it scans the low 64k of memory every 60
1676 seconds; see the memory_corruption_check_size and
1677 memory_corruption_check_period parameters in
1678 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1680 When enabled with the default parameters, this option has
1681 almost no overhead, as it reserves a relatively small amount
1682 of memory and scans it infrequently. It both detects corruption
1683 and prevents it from affecting the running system.
1685 It is, however, intended as a diagnostic tool; if repeatable
1686 BIOS-originated corruption always affects the same memory,
1687 you can use memmap= to prevent the kernel from using that
1690 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1691 bool "Set the default setting of memory_corruption_check"
1692 depends on X86_CHECK_BIOS_CORRUPTION
1695 Set whether the default state of memory_corruption_check is
1698 config X86_RESERVE_LOW
1699 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1703 Specify the amount of low memory to reserve for the BIOS.
1705 The first page contains BIOS data structures that the kernel
1706 must not use, so that page must always be reserved.
1708 By default we reserve the first 64K of physical RAM, as a
1709 number of BIOSes are known to corrupt that memory range
1710 during events such as suspend/resume or monitor cable
1711 insertion, so it must not be used by the kernel.
1713 You can set this to 4 if you are absolutely sure that you
1714 trust the BIOS to get all its memory reservations and usages
1715 right. If you know your BIOS have problems beyond the
1716 default 64K area, you can set this to 640 to avoid using the
1717 entire low memory range.
1719 If you have doubts about the BIOS (e.g. suspend/resume does
1720 not work or there's kernel crashes after certain hardware
1721 hotplug events) then you might want to enable
1722 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1723 typical corruption patterns.
1725 Leave this to the default value of 64 if you are unsure.
1727 config MATH_EMULATION
1729 depends on MODIFY_LDT_SYSCALL
1730 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1732 Linux can emulate a math coprocessor (used for floating point
1733 operations) if you don't have one. 486DX and Pentium processors have
1734 a math coprocessor built in, 486SX and 386 do not, unless you added
1735 a 487DX or 387, respectively. (The messages during boot time can
1736 give you some hints here ["man dmesg"].) Everyone needs either a
1737 coprocessor or this emulation.
1739 If you don't have a math coprocessor, you need to say Y here; if you
1740 say Y here even though you have a coprocessor, the coprocessor will
1741 be used nevertheless. (This behavior can be changed with the kernel
1742 command line option "no387", which comes handy if your coprocessor
1743 is broken. Try "man bootparam" or see the documentation of your boot
1744 loader (lilo or loadlin) about how to pass options to the kernel at
1745 boot time.) This means that it is a good idea to say Y here if you
1746 intend to use this kernel on different machines.
1748 More information about the internals of the Linux math coprocessor
1749 emulation can be found in <file:arch/x86/math-emu/README>.
1751 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1752 kernel, it won't hurt.
1756 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1758 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1759 the Memory Type Range Registers (MTRRs) may be used to control
1760 processor access to memory ranges. This is most useful if you have
1761 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1762 allows bus write transfers to be combined into a larger transfer
1763 before bursting over the PCI/AGP bus. This can increase performance
1764 of image write operations 2.5 times or more. Saying Y here creates a
1765 /proc/mtrr file which may be used to manipulate your processor's
1766 MTRRs. Typically the X server should use this.
1768 This code has a reasonably generic interface so that similar
1769 control registers on other processors can be easily supported
1772 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1773 Registers (ARRs) which provide a similar functionality to MTRRs. For
1774 these, the ARRs are used to emulate the MTRRs.
1775 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1776 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1777 write-combining. All of these processors are supported by this code
1778 and it makes sense to say Y here if you have one of them.
1780 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1781 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1782 can lead to all sorts of problems, so it's good to say Y here.
1784 You can safely say Y even if your machine doesn't have MTRRs, you'll
1785 just add about 9 KB to your kernel.
1787 See <file:Documentation/x86/mtrr.rst> for more information.
1789 config MTRR_SANITIZER
1791 prompt "MTRR cleanup support"
1794 Convert MTRR layout from continuous to discrete, so X drivers can
1795 add writeback entries.
1797 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1798 The largest mtrr entry size for a continuous block can be set with
1803 config MTRR_SANITIZER_ENABLE_DEFAULT
1804 int "MTRR cleanup enable value (0-1)"
1807 depends on MTRR_SANITIZER
1809 Enable mtrr cleanup default value
1811 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1812 int "MTRR cleanup spare reg num (0-7)"
1815 depends on MTRR_SANITIZER
1817 mtrr cleanup spare entries default, it can be changed via
1818 mtrr_spare_reg_nr=N on the kernel command line.
1822 prompt "x86 PAT support" if EXPERT
1825 Use PAT attributes to setup page level cache control.
1827 PATs are the modern equivalents of MTRRs and are much more
1828 flexible than MTRRs.
1830 Say N here if you see bootup problems (boot crash, boot hang,
1831 spontaneous reboots) or a non-working video driver.
1835 config ARCH_USES_PG_UNCACHED
1841 prompt "x86 architectural random number generator" if EXPERT
1843 Enable the x86 architectural RDRAND instruction
1844 (Intel Bull Mountain technology) to generate random numbers.
1845 If supported, this is a high bandwidth, cryptographically
1846 secure hardware random number generator.
1850 prompt "Supervisor Mode Access Prevention" if EXPERT
1852 Supervisor Mode Access Prevention (SMAP) is a security
1853 feature in newer Intel processors. There is a small
1854 performance cost if this enabled and turned on; there is
1855 also a small increase in the kernel size if this is enabled.
1861 prompt "User Mode Instruction Prevention" if EXPERT
1863 User Mode Instruction Prevention (UMIP) is a security feature in
1864 some x86 processors. If enabled, a general protection fault is
1865 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1866 executed in user mode. These instructions unnecessarily expose
1867 information about the hardware state.
1869 The vast majority of applications do not use these instructions.
1870 For the very few that do, software emulation is provided in
1871 specific cases in protected and virtual-8086 modes. Emulated
1874 config X86_INTEL_MEMORY_PROTECTION_KEYS
1875 prompt "Memory Protection Keys"
1877 # Note: only available in 64-bit mode
1878 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1879 select ARCH_USES_HIGH_VMA_FLAGS
1880 select ARCH_HAS_PKEYS
1882 Memory Protection Keys provides a mechanism for enforcing
1883 page-based protections, but without requiring modification of the
1884 page tables when an application changes protection domains.
1886 For details, see Documentation/core-api/protection-keys.rst
1891 prompt "TSX enable mode"
1892 depends on CPU_SUP_INTEL
1893 default X86_INTEL_TSX_MODE_OFF
1895 Intel's TSX (Transactional Synchronization Extensions) feature
1896 allows to optimize locking protocols through lock elision which
1897 can lead to a noticeable performance boost.
1899 On the other hand it has been shown that TSX can be exploited
1900 to form side channel attacks (e.g. TAA) and chances are there
1901 will be more of those attacks discovered in the future.
1903 Therefore TSX is not enabled by default (aka tsx=off). An admin
1904 might override this decision by tsx=on the command line parameter.
1905 Even with TSX enabled, the kernel will attempt to enable the best
1906 possible TAA mitigation setting depending on the microcode available
1907 for the particular machine.
1909 This option allows to set the default tsx mode between tsx=on, =off
1910 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1913 Say off if not sure, auto if TSX is in use but it should be used on safe
1914 platforms or on if TSX is in use and the security aspect of tsx is not
1917 config X86_INTEL_TSX_MODE_OFF
1920 TSX is disabled if possible - equals to tsx=off command line parameter.
1922 config X86_INTEL_TSX_MODE_ON
1925 TSX is always enabled on TSX capable HW - equals the tsx=on command
1928 config X86_INTEL_TSX_MODE_AUTO
1931 TSX is enabled on TSX capable HW that is believed to be safe against
1932 side channel attacks- equals the tsx=auto command line parameter.
1936 bool "Software Guard eXtensions (SGX)"
1937 depends on X86_64 && CPU_SUP_INTEL
1939 depends on CRYPTO_SHA256=y
1943 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1944 that can be used by applications to set aside private regions of code
1945 and data, referred to as enclaves. An enclave's private memory can
1946 only be accessed by code running within the enclave. Accesses from
1947 outside the enclave, including other enclaves, are disallowed by
1953 bool "EFI runtime service support"
1956 select EFI_RUNTIME_WRAPPERS
1958 This enables the kernel to use EFI runtime services that are
1959 available (such as the EFI variable services).
1961 This option is only useful on systems that have EFI firmware.
1962 In addition, you should use the latest ELILO loader available
1963 at <http://elilo.sourceforge.net> in order to take advantage
1964 of EFI runtime services. However, even with this option, the
1965 resultant kernel should continue to boot on existing non-EFI
1969 bool "EFI stub support"
1970 depends on EFI && !X86_USE_3DNOW
1971 depends on $(cc-option,-mabi=ms) || X86_32
1974 This kernel feature allows a bzImage to be loaded directly
1975 by EFI firmware without the use of a bootloader.
1977 See Documentation/admin-guide/efi-stub.rst for more information.
1980 bool "EFI mixed-mode support"
1981 depends on EFI_STUB && X86_64
1983 Enabling this feature allows a 64-bit kernel to be booted
1984 on a 32-bit firmware, provided that your CPU supports 64-bit
1987 Note that it is not possible to boot a mixed-mode enabled
1988 kernel via the EFI boot stub - a bootloader that supports
1989 the EFI handover protocol must be used.
1993 source "kernel/Kconfig.hz"
1996 bool "kexec system call"
1999 kexec is a system call that implements the ability to shutdown your
2000 current kernel, and to start another kernel. It is like a reboot
2001 but it is independent of the system firmware. And like a reboot
2002 you can start any kernel with it, not just Linux.
2004 The name comes from the similarity to the exec system call.
2006 It is an ongoing process to be certain the hardware in a machine
2007 is properly shutdown, so do not be surprised if this code does not
2008 initially work for you. As of this writing the exact hardware
2009 interface is strongly in flux, so no good recommendation can be
2013 bool "kexec file based system call"
2018 depends on CRYPTO_SHA256=y
2020 This is new version of kexec system call. This system call is
2021 file based and takes file descriptors as system call argument
2022 for kernel and initramfs as opposed to list of segments as
2023 accepted by previous system call.
2025 config ARCH_HAS_KEXEC_PURGATORY
2029 bool "Verify kernel signature during kexec_file_load() syscall"
2030 depends on KEXEC_FILE
2033 This option makes the kexec_file_load() syscall check for a valid
2034 signature of the kernel image. The image can still be loaded without
2035 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2036 there's a signature that we can check, then it must be valid.
2038 In addition to this option, you need to enable signature
2039 verification for the corresponding kernel image type being
2040 loaded in order for this to work.
2042 config KEXEC_SIG_FORCE
2043 bool "Require a valid signature in kexec_file_load() syscall"
2044 depends on KEXEC_SIG
2046 This option makes kernel signature verification mandatory for
2047 the kexec_file_load() syscall.
2049 config KEXEC_BZIMAGE_VERIFY_SIG
2050 bool "Enable bzImage signature verification support"
2051 depends on KEXEC_SIG
2052 depends on SIGNED_PE_FILE_VERIFICATION
2053 select SYSTEM_TRUSTED_KEYRING
2055 Enable bzImage signature verification support.
2058 bool "kernel crash dumps"
2059 depends on X86_64 || (X86_32 && HIGHMEM)
2061 Generate crash dump after being started by kexec.
2062 This should be normally only set in special crash dump kernels
2063 which are loaded in the main kernel with kexec-tools into
2064 a specially reserved region and then later executed after
2065 a crash by kdump/kexec. The crash dump kernel must be compiled
2066 to a memory address not used by the main kernel or BIOS using
2067 PHYSICAL_START, or it must be built as a relocatable image
2068 (CONFIG_RELOCATABLE=y).
2069 For more details see Documentation/admin-guide/kdump/kdump.rst
2073 depends on KEXEC && HIBERNATION
2075 Jump between original kernel and kexeced kernel and invoke
2076 code in physical address mode via KEXEC
2078 config PHYSICAL_START
2079 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2082 This gives the physical address where the kernel is loaded.
2084 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2085 bzImage will decompress itself to above physical address and
2086 run from there. Otherwise, bzImage will run from the address where
2087 it has been loaded by the boot loader and will ignore above physical
2090 In normal kdump cases one does not have to set/change this option
2091 as now bzImage can be compiled as a completely relocatable image
2092 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2093 address. This option is mainly useful for the folks who don't want
2094 to use a bzImage for capturing the crash dump and want to use a
2095 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2096 to be specifically compiled to run from a specific memory area
2097 (normally a reserved region) and this option comes handy.
2099 So if you are using bzImage for capturing the crash dump,
2100 leave the value here unchanged to 0x1000000 and set
2101 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2102 for capturing the crash dump change this value to start of
2103 the reserved region. In other words, it can be set based on
2104 the "X" value as specified in the "crashkernel=YM@XM"
2105 command line boot parameter passed to the panic-ed
2106 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2107 for more details about crash dumps.
2109 Usage of bzImage for capturing the crash dump is recommended as
2110 one does not have to build two kernels. Same kernel can be used
2111 as production kernel and capture kernel. Above option should have
2112 gone away after relocatable bzImage support is introduced. But it
2113 is present because there are users out there who continue to use
2114 vmlinux for dump capture. This option should go away down the
2117 Don't change this unless you know what you are doing.
2120 bool "Build a relocatable kernel"
2123 This builds a kernel image that retains relocation information
2124 so it can be loaded someplace besides the default 1MB.
2125 The relocations tend to make the kernel binary about 10% larger,
2126 but are discarded at runtime.
2128 One use is for the kexec on panic case where the recovery kernel
2129 must live at a different physical address than the primary
2132 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2133 it has been loaded at and the compile time physical address
2134 (CONFIG_PHYSICAL_START) is used as the minimum location.
2136 config RANDOMIZE_BASE
2137 bool "Randomize the address of the kernel image (KASLR)"
2138 depends on RELOCATABLE
2141 In support of Kernel Address Space Layout Randomization (KASLR),
2142 this randomizes the physical address at which the kernel image
2143 is decompressed and the virtual address where the kernel
2144 image is mapped, as a security feature that deters exploit
2145 attempts relying on knowledge of the location of kernel
2148 On 64-bit, the kernel physical and virtual addresses are
2149 randomized separately. The physical address will be anywhere
2150 between 16MB and the top of physical memory (up to 64TB). The
2151 virtual address will be randomized from 16MB up to 1GB (9 bits
2152 of entropy). Note that this also reduces the memory space
2153 available to kernel modules from 1.5GB to 1GB.
2155 On 32-bit, the kernel physical and virtual addresses are
2156 randomized together. They will be randomized from 16MB up to
2157 512MB (8 bits of entropy).
2159 Entropy is generated using the RDRAND instruction if it is
2160 supported. If RDTSC is supported, its value is mixed into
2161 the entropy pool as well. If neither RDRAND nor RDTSC are
2162 supported, then entropy is read from the i8254 timer. The
2163 usable entropy is limited by the kernel being built using
2164 2GB addressing, and that PHYSICAL_ALIGN must be at a
2165 minimum of 2MB. As a result, only 10 bits of entropy are
2166 theoretically possible, but the implementations are further
2167 limited due to memory layouts.
2171 # Relocation on x86 needs some additional build support
2172 config X86_NEED_RELOCS
2174 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2176 config PHYSICAL_ALIGN
2177 hex "Alignment value to which kernel should be aligned"
2179 range 0x2000 0x1000000 if X86_32
2180 range 0x200000 0x1000000 if X86_64
2182 This value puts the alignment restrictions on physical address
2183 where kernel is loaded and run from. Kernel is compiled for an
2184 address which meets above alignment restriction.
2186 If bootloader loads the kernel at a non-aligned address and
2187 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2188 address aligned to above value and run from there.
2190 If bootloader loads the kernel at a non-aligned address and
2191 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2192 load address and decompress itself to the address it has been
2193 compiled for and run from there. The address for which kernel is
2194 compiled already meets above alignment restrictions. Hence the
2195 end result is that kernel runs from a physical address meeting
2196 above alignment restrictions.
2198 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2199 this value must be a multiple of 0x200000.
2201 Don't change this unless you know what you are doing.
2203 config DYNAMIC_MEMORY_LAYOUT
2206 This option makes base addresses of vmalloc and vmemmap as well as
2207 __PAGE_OFFSET movable during boot.
2209 config RANDOMIZE_MEMORY
2210 bool "Randomize the kernel memory sections"
2212 depends on RANDOMIZE_BASE
2213 select DYNAMIC_MEMORY_LAYOUT
2214 default RANDOMIZE_BASE
2216 Randomizes the base virtual address of kernel memory sections
2217 (physical memory mapping, vmalloc & vmemmap). This security feature
2218 makes exploits relying on predictable memory locations less reliable.
2220 The order of allocations remains unchanged. Entropy is generated in
2221 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2222 configuration have in average 30,000 different possible virtual
2223 addresses for each memory section.
2227 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2228 hex "Physical memory mapping padding" if EXPERT
2229 depends on RANDOMIZE_MEMORY
2230 default "0xa" if MEMORY_HOTPLUG
2232 range 0x1 0x40 if MEMORY_HOTPLUG
2235 Define the padding in terabytes added to the existing physical
2236 memory size during kernel memory randomization. It is useful
2237 for memory hotplug support but reduces the entropy available for
2238 address randomization.
2240 If unsure, leave at the default value.
2246 config BOOTPARAM_HOTPLUG_CPU0
2247 bool "Set default setting of cpu0_hotpluggable"
2248 depends on HOTPLUG_CPU
2250 Set whether default state of cpu0_hotpluggable is on or off.
2252 Say Y here to enable CPU0 hotplug by default. If this switch
2253 is turned on, there is no need to give cpu0_hotplug kernel
2254 parameter and the CPU0 hotplug feature is enabled by default.
2256 Please note: there are two known CPU0 dependencies if you want
2257 to enable the CPU0 hotplug feature either by this switch or by
2258 cpu0_hotplug kernel parameter.
2260 First, resume from hibernate or suspend always starts from CPU0.
2261 So hibernate and suspend are prevented if CPU0 is offline.
2263 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2264 offline if any interrupt can not migrate out of CPU0. There may
2265 be other CPU0 dependencies.
2267 Please make sure the dependencies are under your control before
2268 you enable this feature.
2270 Say N if you don't want to enable CPU0 hotplug feature by default.
2271 You still can enable the CPU0 hotplug feature at boot by kernel
2272 parameter cpu0_hotplug.
2274 config DEBUG_HOTPLUG_CPU0
2276 prompt "Debug CPU0 hotplug"
2277 depends on HOTPLUG_CPU
2279 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2280 soon as possible and boots up userspace with CPU0 offlined. User
2281 can online CPU0 back after boot time.
2283 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2284 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2285 compilation or giving cpu0_hotplug kernel parameter at boot.
2291 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2292 depends on COMPAT_32
2294 Certain buggy versions of glibc will crash if they are
2295 presented with a 32-bit vDSO that is not mapped at the address
2296 indicated in its segment table.
2298 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2299 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2300 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2301 the only released version with the bug, but OpenSUSE 9
2302 contains a buggy "glibc 2.3.2".
2304 The symptom of the bug is that everything crashes on startup, saying:
2305 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2307 Saying Y here changes the default value of the vdso32 boot
2308 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2309 This works around the glibc bug but hurts performance.
2311 If unsure, say N: if you are compiling your own kernel, you
2312 are unlikely to be using a buggy version of glibc.
2315 prompt "vsyscall table for legacy applications"
2317 default LEGACY_VSYSCALL_XONLY
2319 Legacy user code that does not know how to find the vDSO expects
2320 to be able to issue three syscalls by calling fixed addresses in
2321 kernel space. Since this location is not randomized with ASLR,
2322 it can be used to assist security vulnerability exploitation.
2324 This setting can be changed at boot time via the kernel command
2325 line parameter vsyscall=[emulate|xonly|none].
2327 On a system with recent enough glibc (2.14 or newer) and no
2328 static binaries, you can say None without a performance penalty
2329 to improve security.
2331 If unsure, select "Emulate execution only".
2333 config LEGACY_VSYSCALL_EMULATE
2334 bool "Full emulation"
2336 The kernel traps and emulates calls into the fixed vsyscall
2337 address mapping. This makes the mapping non-executable, but
2338 it still contains readable known contents, which could be
2339 used in certain rare security vulnerability exploits. This
2340 configuration is recommended when using legacy userspace
2341 that still uses vsyscalls along with legacy binary
2342 instrumentation tools that require code to be readable.
2344 An example of this type of legacy userspace is running
2345 Pin on an old binary that still uses vsyscalls.
2347 config LEGACY_VSYSCALL_XONLY
2348 bool "Emulate execution only"
2350 The kernel traps and emulates calls into the fixed vsyscall
2351 address mapping and does not allow reads. This
2352 configuration is recommended when userspace might use the
2353 legacy vsyscall area but support for legacy binary
2354 instrumentation of legacy code is not needed. It mitigates
2355 certain uses of the vsyscall area as an ASLR-bypassing
2358 config LEGACY_VSYSCALL_NONE
2361 There will be no vsyscall mapping at all. This will
2362 eliminate any risk of ASLR bypass due to the vsyscall
2363 fixed address mapping. Attempts to use the vsyscalls
2364 will be reported to dmesg, so that either old or
2365 malicious userspace programs can be identified.
2370 bool "Built-in kernel command line"
2372 Allow for specifying boot arguments to the kernel at
2373 build time. On some systems (e.g. embedded ones), it is
2374 necessary or convenient to provide some or all of the
2375 kernel boot arguments with the kernel itself (that is,
2376 to not rely on the boot loader to provide them.)
2378 To compile command line arguments into the kernel,
2379 set this option to 'Y', then fill in the
2380 boot arguments in CONFIG_CMDLINE.
2382 Systems with fully functional boot loaders (i.e. non-embedded)
2383 should leave this option set to 'N'.
2386 string "Built-in kernel command string"
2387 depends on CMDLINE_BOOL
2390 Enter arguments here that should be compiled into the kernel
2391 image and used at boot time. If the boot loader provides a
2392 command line at boot time, it is appended to this string to
2393 form the full kernel command line, when the system boots.
2395 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2396 change this behavior.
2398 In most cases, the command line (whether built-in or provided
2399 by the boot loader) should specify the device for the root
2402 config CMDLINE_OVERRIDE
2403 bool "Built-in command line overrides boot loader arguments"
2404 depends on CMDLINE_BOOL && CMDLINE != ""
2406 Set this option to 'Y' to have the kernel ignore the boot loader
2407 command line, and use ONLY the built-in command line.
2409 This is used to work around broken boot loaders. This should
2410 be set to 'N' under normal conditions.
2412 config MODIFY_LDT_SYSCALL
2413 bool "Enable the LDT (local descriptor table)" if EXPERT
2416 Linux can allow user programs to install a per-process x86
2417 Local Descriptor Table (LDT) using the modify_ldt(2) system
2418 call. This is required to run 16-bit or segmented code such as
2419 DOSEMU or some Wine programs. It is also used by some very old
2420 threading libraries.
2422 Enabling this feature adds a small amount of overhead to
2423 context switches and increases the low-level kernel attack
2424 surface. Disabling it removes the modify_ldt(2) system call.
2426 Saying 'N' here may make sense for embedded or server kernels.
2428 source "kernel/livepatch/Kconfig"
2432 config ARCH_HAS_ADD_PAGES
2434 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2436 config ARCH_ENABLE_MEMORY_HOTPLUG
2438 depends on X86_64 || (X86_32 && HIGHMEM)
2440 config ARCH_ENABLE_MEMORY_HOTREMOVE
2442 depends on MEMORY_HOTPLUG
2444 config USE_PERCPU_NUMA_NODE_ID
2448 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2450 depends on X86_64 || X86_PAE
2452 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2454 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2456 config ARCH_ENABLE_THP_MIGRATION
2458 depends on X86_64 && TRANSPARENT_HUGEPAGE
2460 menu "Power management and ACPI options"
2462 config ARCH_HIBERNATION_HEADER
2464 depends on HIBERNATION
2466 source "kernel/power/Kconfig"
2468 source "drivers/acpi/Kconfig"
2470 source "drivers/sfi/Kconfig"
2477 tristate "APM (Advanced Power Management) BIOS support"
2478 depends on X86_32 && PM_SLEEP
2480 APM is a BIOS specification for saving power using several different
2481 techniques. This is mostly useful for battery powered laptops with
2482 APM compliant BIOSes. If you say Y here, the system time will be
2483 reset after a RESUME operation, the /proc/apm device will provide
2484 battery status information, and user-space programs will receive
2485 notification of APM "events" (e.g. battery status change).
2487 If you select "Y" here, you can disable actual use of the APM
2488 BIOS by passing the "apm=off" option to the kernel at boot time.
2490 Note that the APM support is almost completely disabled for
2491 machines with more than one CPU.
2493 In order to use APM, you will need supporting software. For location
2494 and more information, read <file:Documentation/power/apm-acpi.rst>
2495 and the Battery Powered Linux mini-HOWTO, available from
2496 <http://www.tldp.org/docs.html#howto>.
2498 This driver does not spin down disk drives (see the hdparm(8)
2499 manpage ("man 8 hdparm") for that), and it doesn't turn off
2500 VESA-compliant "green" monitors.
2502 This driver does not support the TI 4000M TravelMate and the ACER
2503 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2504 desktop machines also don't have compliant BIOSes, and this driver
2505 may cause those machines to panic during the boot phase.
2507 Generally, if you don't have a battery in your machine, there isn't
2508 much point in using this driver and you should say N. If you get
2509 random kernel OOPSes or reboots that don't seem to be related to
2510 anything, try disabling/enabling this option (or disabling/enabling
2513 Some other things you should try when experiencing seemingly random,
2516 1) make sure that you have enough swap space and that it is
2518 2) pass the "no-hlt" option to the kernel
2519 3) switch on floating point emulation in the kernel and pass
2520 the "no387" option to the kernel
2521 4) pass the "floppy=nodma" option to the kernel
2522 5) pass the "mem=4M" option to the kernel (thereby disabling
2523 all but the first 4 MB of RAM)
2524 6) make sure that the CPU is not over clocked.
2525 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2526 8) disable the cache from your BIOS settings
2527 9) install a fan for the video card or exchange video RAM
2528 10) install a better fan for the CPU
2529 11) exchange RAM chips
2530 12) exchange the motherboard.
2532 To compile this driver as a module, choose M here: the
2533 module will be called apm.
2537 config APM_IGNORE_USER_SUSPEND
2538 bool "Ignore USER SUSPEND"
2540 This option will ignore USER SUSPEND requests. On machines with a
2541 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2542 series notebooks, it is necessary to say Y because of a BIOS bug.
2544 config APM_DO_ENABLE
2545 bool "Enable PM at boot time"
2547 Enable APM features at boot time. From page 36 of the APM BIOS
2548 specification: "When disabled, the APM BIOS does not automatically
2549 power manage devices, enter the Standby State, enter the Suspend
2550 State, or take power saving steps in response to CPU Idle calls."
2551 This driver will make CPU Idle calls when Linux is idle (unless this
2552 feature is turned off -- see "Do CPU IDLE calls", below). This
2553 should always save battery power, but more complicated APM features
2554 will be dependent on your BIOS implementation. You may need to turn
2555 this option off if your computer hangs at boot time when using APM
2556 support, or if it beeps continuously instead of suspending. Turn
2557 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2558 T400CDT. This is off by default since most machines do fine without
2563 bool "Make CPU Idle calls when idle"
2565 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2566 On some machines, this can activate improved power savings, such as
2567 a slowed CPU clock rate, when the machine is idle. These idle calls
2568 are made after the idle loop has run for some length of time (e.g.,
2569 333 mS). On some machines, this will cause a hang at boot time or
2570 whenever the CPU becomes idle. (On machines with more than one CPU,
2571 this option does nothing.)
2573 config APM_DISPLAY_BLANK
2574 bool "Enable console blanking using APM"
2576 Enable console blanking using the APM. Some laptops can use this to
2577 turn off the LCD backlight when the screen blanker of the Linux
2578 virtual console blanks the screen. Note that this is only used by
2579 the virtual console screen blanker, and won't turn off the backlight
2580 when using the X Window system. This also doesn't have anything to
2581 do with your VESA-compliant power-saving monitor. Further, this
2582 option doesn't work for all laptops -- it might not turn off your
2583 backlight at all, or it might print a lot of errors to the console,
2584 especially if you are using gpm.
2586 config APM_ALLOW_INTS
2587 bool "Allow interrupts during APM BIOS calls"
2589 Normally we disable external interrupts while we are making calls to
2590 the APM BIOS as a measure to lessen the effects of a badly behaving
2591 BIOS implementation. The BIOS should reenable interrupts if it
2592 needs to. Unfortunately, some BIOSes do not -- especially those in
2593 many of the newer IBM Thinkpads. If you experience hangs when you
2594 suspend, try setting this to Y. Otherwise, say N.
2598 source "drivers/cpufreq/Kconfig"
2600 source "drivers/cpuidle/Kconfig"
2602 source "drivers/idle/Kconfig"
2607 menu "Bus options (PCI etc.)"
2610 prompt "PCI access mode"
2611 depends on X86_32 && PCI
2614 On PCI systems, the BIOS can be used to detect the PCI devices and
2615 determine their configuration. However, some old PCI motherboards
2616 have BIOS bugs and may crash if this is done. Also, some embedded
2617 PCI-based systems don't have any BIOS at all. Linux can also try to
2618 detect the PCI hardware directly without using the BIOS.
2620 With this option, you can specify how Linux should detect the
2621 PCI devices. If you choose "BIOS", the BIOS will be used,
2622 if you choose "Direct", the BIOS won't be used, and if you
2623 choose "MMConfig", then PCI Express MMCONFIG will be used.
2624 If you choose "Any", the kernel will try MMCONFIG, then the
2625 direct access method and falls back to the BIOS if that doesn't
2626 work. If unsure, go with the default, which is "Any".
2631 config PCI_GOMMCONFIG
2648 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2650 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2653 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2656 bool "Support mmconfig PCI config space access" if X86_64
2658 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2659 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2663 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2667 depends on PCI && XEN
2670 config MMCONF_FAM10H
2672 depends on X86_64 && PCI_MMCONFIG && ACPI
2674 config PCI_CNB20LE_QUIRK
2675 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2678 Read the PCI windows out of the CNB20LE host bridge. This allows
2679 PCI hotplug to work on systems with the CNB20LE chipset which do
2682 There's no public spec for this chipset, and this functionality
2683 is known to be incomplete.
2685 You should say N unless you know you need this.
2688 bool "ISA bus support on modern systems" if EXPERT
2690 Expose ISA bus device drivers and options available for selection and
2691 configuration. Enable this option if your target machine has an ISA
2692 bus. ISA is an older system, displaced by PCI and newer bus
2693 architectures -- if your target machine is modern, it probably does
2694 not have an ISA bus.
2698 # x86_64 have no ISA slots, but can have ISA-style DMA.
2700 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2703 Enables ISA-style DMA support for devices requiring such controllers.
2711 Find out whether you have ISA slots on your motherboard. ISA is the
2712 name of a bus system, i.e. the way the CPU talks to the other stuff
2713 inside your box. Other bus systems are PCI, EISA, MicroChannel
2714 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2715 newer boards don't support it. If you have ISA, say Y, otherwise N.
2718 tristate "NatSemi SCx200 support"
2720 This provides basic support for National Semiconductor's
2721 (now AMD's) Geode processors. The driver probes for the
2722 PCI-IDs of several on-chip devices, so its a good dependency
2723 for other scx200_* drivers.
2725 If compiled as a module, the driver is named scx200.
2727 config SCx200HR_TIMER
2728 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2732 This driver provides a clocksource built upon the on-chip
2733 27MHz high-resolution timer. Its also a workaround for
2734 NSC Geode SC-1100's buggy TSC, which loses time when the
2735 processor goes idle (as is done by the scheduler). The
2736 other workaround is idle=poll boot option.
2739 bool "One Laptop Per Child support"
2747 Add support for detecting the unique features of the OLPC
2751 bool "OLPC XO-1 Power Management"
2752 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2754 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2757 bool "OLPC XO-1 Real Time Clock"
2758 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2760 Add support for the XO-1 real time clock, which can be used as a
2761 programmable wakeup source.
2764 bool "OLPC XO-1 SCI extras"
2765 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2769 Add support for SCI-based features of the OLPC XO-1 laptop:
2770 - EC-driven system wakeups
2774 - AC adapter status updates
2775 - Battery status updates
2777 config OLPC_XO15_SCI
2778 bool "OLPC XO-1.5 SCI extras"
2779 depends on OLPC && ACPI
2782 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2783 - EC-driven system wakeups
2784 - AC adapter status updates
2785 - Battery status updates
2788 bool "PCEngines ALIX System Support (LED setup)"
2791 This option enables system support for the PCEngines ALIX.
2792 At present this just sets up LEDs for GPIO control on
2793 ALIX2/3/6 boards. However, other system specific setup should
2796 Note: You must still enable the drivers for GPIO and LED support
2797 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2799 Note: You have to set alix.force=1 for boards with Award BIOS.
2802 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2805 This option enables system support for the Soekris Engineering net5501.
2808 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2812 This option enables system support for the Traverse Technologies GEOS.
2815 bool "Technologic Systems TS-5500 platform support"
2817 select CHECK_SIGNATURE
2821 This option enables system support for the Technologic Systems TS-5500.
2827 depends on CPU_SUP_AMD && PCI
2830 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2832 Firmwares often provide initial graphics framebuffers so the BIOS,
2833 bootloader or kernel can show basic video-output during boot for
2834 user-guidance and debugging. Historically, x86 used the VESA BIOS
2835 Extensions and EFI-framebuffers for this, which are mostly limited
2837 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2838 framebuffers so the new generic system-framebuffer drivers can be
2839 used on x86. If the framebuffer is not compatible with the generic
2840 modes, it is advertised as fallback platform framebuffer so legacy
2841 drivers like efifb, vesafb and uvesafb can pick it up.
2842 If this option is not selected, all system framebuffers are always
2843 marked as fallback platform framebuffers as usual.
2845 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2846 not be able to pick up generic system framebuffers if this option
2847 is selected. You are highly encouraged to enable simplefb as
2848 replacement if you select this option. simplefb can correctly deal
2849 with generic system framebuffers. But you should still keep vesafb
2850 and others enabled as fallback if a system framebuffer is
2851 incompatible with simplefb.
2858 menu "Binary Emulations"
2860 config IA32_EMULATION
2861 bool "IA32 Emulation"
2863 select ARCH_WANT_OLD_COMPAT_IPC
2865 select COMPAT_BINFMT_ELF
2866 select COMPAT_OLD_SIGACTION
2868 Include code to run legacy 32-bit programs under a
2869 64-bit kernel. You should likely turn this on, unless you're
2870 100% sure that you don't have any 32-bit programs left.
2873 tristate "IA32 a.out support"
2874 depends on IA32_EMULATION
2877 Support old a.out binaries in the 32bit emulation.
2880 bool "x32 ABI for 64-bit mode"
2883 Include code to run binaries for the x32 native 32-bit ABI
2884 for 64-bit processors. An x32 process gets access to the
2885 full 64-bit register file and wide data path while leaving
2886 pointers at 32 bits for smaller memory footprint.
2888 You will need a recent binutils (2.22 or later) with
2889 elf32_x86_64 support enabled to compile a kernel with this
2894 depends on IA32_EMULATION || X86_32
2896 select OLD_SIGSUSPEND3
2900 depends on IA32_EMULATION || X86_X32
2903 config COMPAT_FOR_U64_ALIGNMENT
2906 config SYSVIPC_COMPAT
2914 config HAVE_ATOMIC_IOMAP
2918 source "drivers/firmware/Kconfig"
2920 source "arch/x86/kvm/Kconfig"
2922 source "arch/x86/Kconfig.assembler"