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 GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
65 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 || (X86_32 && HIGHMEM)
66 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
67 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
68 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
69 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
70 select ARCH_HAS_CACHE_LINE_SIZE
71 select ARCH_HAS_DEBUG_VIRTUAL
72 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
73 select ARCH_HAS_DEVMEM_IS_ALLOWED
74 select ARCH_HAS_EARLY_DEBUG if KGDB
75 select ARCH_HAS_ELF_RANDOMIZE
76 select ARCH_HAS_FAST_MULTIPLIER
77 select ARCH_HAS_FILTER_PGPROT
78 select ARCH_HAS_FORTIFY_SOURCE
79 select ARCH_HAS_GCOV_PROFILE_ALL
80 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
81 select ARCH_HAS_MEM_ENCRYPT
82 select ARCH_HAS_MEMBARRIER_SYNC_CORE
83 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
84 select ARCH_HAS_PMEM_API if X86_64
85 select ARCH_HAS_PTE_DEVMAP if X86_64
86 select ARCH_HAS_PTE_SPECIAL
87 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
88 select ARCH_HAS_COPY_MC if X86_64
89 select ARCH_HAS_SET_MEMORY
90 select ARCH_HAS_SET_DIRECT_MAP
91 select ARCH_HAS_STRICT_KERNEL_RWX
92 select ARCH_HAS_STRICT_MODULE_RWX
93 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
94 select ARCH_HAS_SYSCALL_WRAPPER
95 select ARCH_HAS_UBSAN_SANITIZE_ALL
96 select ARCH_HAS_DEBUG_WX
97 select ARCH_HAS_ZONE_DMA_SET if EXPERT
98 select ARCH_HAVE_NMI_SAFE_CMPXCHG
99 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
100 select ARCH_MIGHT_HAVE_PC_PARPORT
101 select ARCH_MIGHT_HAVE_PC_SERIO
102 select ARCH_STACKWALK
103 select ARCH_SUPPORTS_ACPI
104 select ARCH_SUPPORTS_ATOMIC_RMW
105 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
106 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
107 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
108 select ARCH_SUPPORTS_LTO_CLANG
109 select ARCH_SUPPORTS_LTO_CLANG_THIN
110 select ARCH_USE_BUILTIN_BSWAP
111 select ARCH_USE_MEMTEST
112 select ARCH_USE_QUEUED_RWLOCKS
113 select ARCH_USE_QUEUED_SPINLOCKS
114 select ARCH_USE_SYM_ANNOTATIONS
115 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
116 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
117 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
118 select ARCH_WANTS_NO_INSTR
119 select ARCH_WANT_HUGE_PMD_SHARE
120 select ARCH_WANT_LD_ORPHAN_WARN
121 select ARCH_WANTS_THP_SWAP if X86_64
122 select ARCH_HAS_PARANOID_L1D_FLUSH
123 select BUILDTIME_TABLE_SORT
125 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
126 select CLOCKSOURCE_WATCHDOG
127 select DCACHE_WORD_ACCESS
128 select EDAC_ATOMIC_SCRUB
130 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
131 select GENERIC_CLOCKEVENTS_MIN_ADJUST
132 select GENERIC_CMOS_UPDATE
133 select GENERIC_CPU_AUTOPROBE
134 select GENERIC_CPU_VULNERABILITIES
135 select GENERIC_EARLY_IOREMAP
137 select GENERIC_FIND_FIRST_BIT
139 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
140 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
141 select GENERIC_IRQ_MIGRATION if SMP
142 select GENERIC_IRQ_PROBE
143 select GENERIC_IRQ_RESERVATION_MODE
144 select GENERIC_IRQ_SHOW
145 select GENERIC_PENDING_IRQ if SMP
146 select GENERIC_PTDUMP
147 select GENERIC_SMP_IDLE_THREAD
148 select GENERIC_TIME_VSYSCALL
149 select GENERIC_GETTIMEOFDAY
150 select GENERIC_VDSO_TIME_NS
151 select GUP_GET_PTE_LOW_HIGH if X86_PAE
152 select HARDIRQS_SW_RESEND
153 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
154 select HAVE_ACPI_APEI if ACPI
155 select HAVE_ACPI_APEI_NMI if ACPI
156 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
157 select HAVE_ARCH_AUDITSYSCALL
158 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
159 select HAVE_ARCH_JUMP_LABEL
160 select HAVE_ARCH_JUMP_LABEL_RELATIVE
161 select HAVE_ARCH_KASAN if X86_64
162 select HAVE_ARCH_KASAN_VMALLOC if X86_64
163 select HAVE_ARCH_KFENCE
164 select HAVE_ARCH_KGDB
165 select HAVE_ARCH_MMAP_RND_BITS if MMU
166 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
167 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
168 select HAVE_ARCH_PREL32_RELOCATIONS
169 select HAVE_ARCH_SECCOMP_FILTER
170 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
171 select HAVE_ARCH_STACKLEAK
172 select HAVE_ARCH_TRACEHOOK
173 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
174 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
175 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
176 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
177 select HAVE_ARCH_VMAP_STACK if X86_64
178 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
179 select HAVE_ARCH_WITHIN_STACK_FRAMES
180 select HAVE_ASM_MODVERSIONS
181 select HAVE_CMPXCHG_DOUBLE
182 select HAVE_CMPXCHG_LOCAL
183 select HAVE_CONTEXT_TRACKING if X86_64
184 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
185 select HAVE_C_RECORDMCOUNT
186 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
187 select HAVE_DEBUG_KMEMLEAK
188 select HAVE_DMA_CONTIGUOUS
189 select HAVE_DYNAMIC_FTRACE
190 select HAVE_DYNAMIC_FTRACE_WITH_REGS
191 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
192 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
194 select HAVE_EFFICIENT_UNALIGNED_ACCESS
196 select HAVE_EXIT_THREAD
198 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
199 select HAVE_FTRACE_MCOUNT_RECORD
200 select HAVE_FUNCTION_GRAPH_TRACER
201 select HAVE_FUNCTION_TRACER
202 select HAVE_GCC_PLUGINS
203 select HAVE_HW_BREAKPOINT
204 select HAVE_IOREMAP_PROT
205 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
206 select HAVE_IRQ_TIME_ACCOUNTING
207 select HAVE_KERNEL_BZIP2
208 select HAVE_KERNEL_GZIP
209 select HAVE_KERNEL_LZ4
210 select HAVE_KERNEL_LZMA
211 select HAVE_KERNEL_LZO
212 select HAVE_KERNEL_XZ
213 select HAVE_KERNEL_ZSTD
215 select HAVE_KPROBES_ON_FTRACE
216 select HAVE_FUNCTION_ERROR_INJECTION
217 select HAVE_KRETPROBES
219 select HAVE_LIVEPATCH if X86_64
220 select HAVE_MIXED_BREAKPOINTS_REGS
221 select HAVE_MOD_ARCH_SPECIFIC
225 select HAVE_OPTPROBES
226 select HAVE_PCSPKR_PLATFORM
227 select HAVE_PERF_EVENTS
228 select HAVE_PERF_EVENTS_NMI
229 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
231 select HAVE_PERF_REGS
232 select HAVE_PERF_USER_STACK_DUMP
233 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
234 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
235 select HAVE_REGS_AND_STACK_ACCESS_API
236 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
237 select HAVE_FUNCTION_ARG_ACCESS_API
238 select HAVE_SOFTIRQ_ON_OWN_STACK
239 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
240 select HAVE_STACK_VALIDATION if X86_64
241 select HAVE_STATIC_CALL
242 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
243 select HAVE_PREEMPT_DYNAMIC
245 select HAVE_SYSCALL_TRACEPOINTS
246 select HAVE_UNSTABLE_SCHED_CLOCK
247 select HAVE_USER_RETURN_NOTIFIER
248 select HAVE_GENERIC_VDSO
249 select HOTPLUG_SMT if SMP
250 select IRQ_FORCED_THREADING
251 select NEED_SG_DMA_LENGTH
252 select PCI_DOMAINS if PCI
253 select PCI_LOCKLESS_CONFIG if PCI
256 select RTC_MC146818_LIB
259 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
260 select SYSCTL_EXCEPTION_TRACE
261 select THREAD_INFO_IN_TASK
262 select USER_STACKTRACE_SUPPORT
264 select HAVE_ARCH_KCSAN if X86_64
265 select X86_FEATURE_NAMES if PROC_FS
266 select PROC_PID_ARCH_STATUS if PROC_FS
267 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
269 config INSTRUCTION_DECODER
271 depends on KPROBES || PERF_EVENTS || UPROBES
275 default "elf32-i386" if X86_32
276 default "elf64-x86-64" if X86_64
278 config LOCKDEP_SUPPORT
281 config STACKTRACE_SUPPORT
287 config ARCH_MMAP_RND_BITS_MIN
291 config ARCH_MMAP_RND_BITS_MAX
295 config ARCH_MMAP_RND_COMPAT_BITS_MIN
298 config ARCH_MMAP_RND_COMPAT_BITS_MAX
304 config GENERIC_ISA_DMA
306 depends on ISA_DMA_API
311 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
313 config GENERIC_BUG_RELATIVE_POINTERS
316 config ARCH_MAY_HAVE_PC_FDC
318 depends on ISA_DMA_API
320 config GENERIC_CALIBRATE_DELAY
323 config ARCH_HAS_CPU_RELAX
326 config ARCH_HAS_FILTER_PGPROT
329 config HAVE_SETUP_PER_CPU_AREA
332 config NEED_PER_CPU_EMBED_FIRST_CHUNK
335 config NEED_PER_CPU_PAGE_FIRST_CHUNK
338 config ARCH_HIBERNATION_POSSIBLE
341 config ARCH_SUSPEND_POSSIBLE
344 config ARCH_WANT_GENERAL_HUGETLB
350 config KASAN_SHADOW_OFFSET
353 default 0xdffffc0000000000
355 config HAVE_INTEL_TXT
357 depends on INTEL_IOMMU && ACPI
361 depends on X86_32 && SMP
365 depends on X86_64 && SMP
367 config ARCH_SUPPORTS_UPROBES
370 config FIX_EARLYCON_MEM
373 config DYNAMIC_PHYSICAL_MASK
376 config PGTABLE_LEVELS
378 default 5 if X86_5LEVEL
383 config CC_HAS_SANE_STACKPROTECTOR
385 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
386 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
388 We have to make sure stack protector is unconditionally disabled if
389 the compiler produces broken code or if it does not let us control
390 the segment on 32-bit kernels.
392 menu "Processor type and features"
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
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 KEXEC_CORE
566 depends on X86_X2APIC
569 This option is needed in order to support SGI Ultraviolet systems.
570 If you don't have one of these, you should say N here.
572 # Following is an alphabetically sorted list of 32 bit extended platforms
573 # Please maintain the alphabetic order if and when there are additions
576 bool "Goldfish (Virtual Platform)"
577 depends on X86_EXTENDED_PLATFORM
579 Enable support for the Goldfish virtual platform used primarily
580 for Android development. Unless you are building for the Android
581 Goldfish emulator say N here.
584 bool "CE4100 TV platform"
586 depends on PCI_GODIRECT
587 depends on X86_IO_APIC
589 depends on X86_EXTENDED_PLATFORM
590 select X86_REBOOTFIXUPS
592 select OF_EARLY_FLATTREE
594 Select for the Intel CE media processor (CE4100) SOC.
595 This option compiles in support for the CE4100 SOC for settop
596 boxes and media devices.
599 bool "Intel MID platform support"
600 depends on X86_EXTENDED_PLATFORM
601 depends on X86_PLATFORM_DEVICES
603 depends on X86_64 || (PCI_GOANY && X86_32)
604 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"
772 depends on HAVE_STATIC_CALL
774 This changes the kernel so it can modify itself when it is run
775 under a hypervisor, potentially improving performance significantly
776 over full virtualization. However, when run without a hypervisor
777 the kernel is theoretically slower and slightly larger.
782 config PARAVIRT_DEBUG
783 bool "paravirt-ops debugging"
784 depends on PARAVIRT && DEBUG_KERNEL
786 Enable to debug paravirt_ops internals. Specifically, BUG if
787 a paravirt_op is missing when it is called.
789 config PARAVIRT_SPINLOCKS
790 bool "Paravirtualization layer for spinlocks"
791 depends on PARAVIRT && SMP
793 Paravirtualized spinlocks allow a pvops backend to replace the
794 spinlock implementation with something virtualization-friendly
795 (for example, block the virtual CPU rather than spinning).
797 It has a minimal impact on native kernels and gives a nice performance
798 benefit on paravirtualized KVM / Xen kernels.
800 If you are unsure how to answer this question, answer Y.
802 config X86_HV_CALLBACK_VECTOR
805 source "arch/x86/xen/Kconfig"
808 bool "KVM Guest support (including kvmclock)"
810 select PARAVIRT_CLOCK
811 select ARCH_CPUIDLE_HALTPOLL
812 select X86_HV_CALLBACK_VECTOR
815 This option enables various optimizations for running under the KVM
816 hypervisor. It includes a paravirtualized clock, so that instead
817 of relying on a PIT (or probably other) emulation by the
818 underlying device model, the host provides the guest with
819 timing infrastructure such as time of day, and system time
821 config ARCH_CPUIDLE_HALTPOLL
823 prompt "Disable host haltpoll when loading haltpoll driver"
825 If virtualized under KVM, disable host haltpoll.
828 bool "Support for running PVH guests"
830 This option enables the PVH entry point for guest virtual machines
831 as specified in the x86/HVM direct boot ABI.
833 config PARAVIRT_TIME_ACCOUNTING
834 bool "Paravirtual steal time accounting"
837 Select this option to enable fine granularity task steal time
838 accounting. Time spent executing other tasks in parallel with
839 the current vCPU is discounted from the vCPU power. To account for
840 that, there can be a small performance impact.
842 If in doubt, say N here.
844 config PARAVIRT_CLOCK
847 config JAILHOUSE_GUEST
848 bool "Jailhouse non-root cell support"
849 depends on X86_64 && PCI
852 This option allows to run Linux as guest in a Jailhouse non-root
853 cell. You can leave this option disabled if you only want to start
854 Jailhouse and run Linux afterwards in the root cell.
857 bool "ACRN Guest support"
859 select X86_HV_CALLBACK_VECTOR
861 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
862 a flexible, lightweight reference open-source hypervisor, built with
863 real-time and safety-criticality in mind. It is built for embedded
864 IOT with small footprint and real-time features. More details can be
865 found in https://projectacrn.org/.
867 endif #HYPERVISOR_GUEST
869 source "arch/x86/Kconfig.cpu"
873 prompt "HPET Timer Support" if X86_32
875 Use the IA-PC HPET (High Precision Event Timer) to manage
876 time in preference to the PIT and RTC, if a HPET is
878 HPET is the next generation timer replacing legacy 8254s.
879 The HPET provides a stable time base on SMP
880 systems, unlike the TSC, but it is more expensive to access,
881 as it is off-chip. The interface used is documented
882 in the HPET spec, revision 1.
884 You can safely choose Y here. However, HPET will only be
885 activated if the platform and the BIOS support this feature.
886 Otherwise the 8254 will be used for timing services.
888 Choose N to continue using the legacy 8254 timer.
890 config HPET_EMULATE_RTC
892 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
894 # Mark as expert because too many people got it wrong.
895 # The code disables itself when not needed.
898 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
899 bool "Enable DMI scanning" if EXPERT
901 Enabled scanning of DMI to identify machine quirks. Say Y
902 here unless you have verified that your setup is not
903 affected by entries in the DMI blacklist. Required by PNP
907 bool "Old AMD GART IOMMU support"
911 depends on X86_64 && PCI && AMD_NB
913 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
914 GART based hardware IOMMUs.
916 The GART supports full DMA access for devices with 32-bit access
917 limitations, on systems with more than 3 GB. This is usually needed
918 for USB, sound, many IDE/SATA chipsets and some other devices.
920 Newer systems typically have a modern AMD IOMMU, supported via
921 the CONFIG_AMD_IOMMU=y config option.
923 In normal configurations this driver is only active when needed:
924 there's more than 3 GB of memory and the system contains a
925 32-bit limited device.
930 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
931 depends on X86_64 && SMP && DEBUG_KERNEL
932 select CPUMASK_OFFSTACK
934 Enable maximum number of CPUS and NUMA Nodes for this architecture.
938 # The maximum number of CPUs supported:
940 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
941 # and which can be configured interactively in the
942 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
944 # The ranges are different on 32-bit and 64-bit kernels, depending on
945 # hardware capabilities and scalability features of the kernel.
947 # ( If MAXSMP is enabled we just use the highest possible value and disable
948 # interactive configuration. )
951 config NR_CPUS_RANGE_BEGIN
953 default NR_CPUS_RANGE_END if MAXSMP
957 config NR_CPUS_RANGE_END
960 default 64 if SMP && X86_BIGSMP
961 default 8 if SMP && !X86_BIGSMP
964 config NR_CPUS_RANGE_END
967 default 8192 if SMP && CPUMASK_OFFSTACK
968 default 512 if SMP && !CPUMASK_OFFSTACK
971 config NR_CPUS_DEFAULT
974 default 32 if X86_BIGSMP
978 config NR_CPUS_DEFAULT
981 default 8192 if MAXSMP
986 int "Maximum number of CPUs" if SMP && !MAXSMP
987 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
988 default NR_CPUS_DEFAULT
990 This allows you to specify the maximum number of CPUs which this
991 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
992 supported value is 8192, otherwise the maximum value is 512. The
993 minimum value which makes sense is 2.
995 This is purely to save memory: each supported CPU adds about 8KB
1003 prompt "Multi-core scheduler support"
1006 Multi-core scheduler support improves the CPU scheduler's decision
1007 making when dealing with multi-core CPU chips at a cost of slightly
1008 increased overhead in some places. If unsure say N here.
1010 config SCHED_MC_PRIO
1011 bool "CPU core priorities scheduler support"
1012 depends on SCHED_MC && CPU_SUP_INTEL
1013 select X86_INTEL_PSTATE
1017 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1018 core ordering determined at manufacturing time, which allows
1019 certain cores to reach higher turbo frequencies (when running
1020 single threaded workloads) than others.
1022 Enabling this kernel feature teaches the scheduler about
1023 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1024 scheduler's CPU selection logic accordingly, so that higher
1025 overall system performance can be achieved.
1027 This feature will have no effect on CPUs without this feature.
1029 If unsure say Y here.
1033 depends on !SMP && X86_LOCAL_APIC
1036 bool "Local APIC support on uniprocessors" if !PCI_MSI
1038 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1040 A local APIC (Advanced Programmable Interrupt Controller) is an
1041 integrated interrupt controller in the CPU. If you have a single-CPU
1042 system which has a processor with a local APIC, you can say Y here to
1043 enable and use it. If you say Y here even though your machine doesn't
1044 have a local APIC, then the kernel will still run with no slowdown at
1045 all. The local APIC supports CPU-generated self-interrupts (timer,
1046 performance counters), and the NMI watchdog which detects hard
1049 config X86_UP_IOAPIC
1050 bool "IO-APIC support on uniprocessors"
1051 depends on X86_UP_APIC
1053 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1054 SMP-capable replacement for PC-style interrupt controllers. Most
1055 SMP systems and many recent uniprocessor systems have one.
1057 If you have a single-CPU system with an IO-APIC, you can say Y here
1058 to use it. If you say Y here even though your machine doesn't have
1059 an IO-APIC, then the kernel will still run with no slowdown at all.
1061 config X86_LOCAL_APIC
1063 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1064 select IRQ_DOMAIN_HIERARCHY
1065 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1069 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1071 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1072 bool "Reroute for broken boot IRQs"
1073 depends on X86_IO_APIC
1075 This option enables a workaround that fixes a source of
1076 spurious interrupts. This is recommended when threaded
1077 interrupt handling is used on systems where the generation of
1078 superfluous "boot interrupts" cannot be disabled.
1080 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1081 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1082 kernel does during interrupt handling). On chipsets where this
1083 boot IRQ generation cannot be disabled, this workaround keeps
1084 the original IRQ line masked so that only the equivalent "boot
1085 IRQ" is delivered to the CPUs. The workaround also tells the
1086 kernel to set up the IRQ handler on the boot IRQ line. In this
1087 way only one interrupt is delivered to the kernel. Otherwise
1088 the spurious second interrupt may cause the kernel to bring
1089 down (vital) interrupt lines.
1091 Only affects "broken" chipsets. Interrupt sharing may be
1092 increased on these systems.
1095 bool "Machine Check / overheating reporting"
1096 select GENERIC_ALLOCATOR
1099 Machine Check support allows the processor to notify the
1100 kernel if it detects a problem (e.g. overheating, data corruption).
1101 The action the kernel takes depends on the severity of the problem,
1102 ranging from warning messages to halting the machine.
1104 config X86_MCELOG_LEGACY
1105 bool "Support for deprecated /dev/mcelog character device"
1108 Enable support for /dev/mcelog which is needed by the old mcelog
1109 userspace logging daemon. Consider switching to the new generation
1112 config X86_MCE_INTEL
1114 prompt "Intel MCE features"
1115 depends on X86_MCE && X86_LOCAL_APIC
1117 Additional support for intel specific MCE features such as
1118 the thermal monitor.
1122 prompt "AMD MCE features"
1123 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1125 Additional support for AMD specific MCE features such as
1126 the DRAM Error Threshold.
1128 config X86_ANCIENT_MCE
1129 bool "Support for old Pentium 5 / WinChip machine checks"
1130 depends on X86_32 && X86_MCE
1132 Include support for machine check handling on old Pentium 5 or WinChip
1133 systems. These typically need to be enabled explicitly on the command
1136 config X86_MCE_THRESHOLD
1137 depends on X86_MCE_AMD || X86_MCE_INTEL
1140 config X86_MCE_INJECT
1141 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1142 tristate "Machine check injector support"
1144 Provide support for injecting machine checks for testing purposes.
1145 If you don't know what a machine check is and you don't do kernel
1146 QA it is safe to say n.
1148 source "arch/x86/events/Kconfig"
1150 config X86_LEGACY_VM86
1151 bool "Legacy VM86 support"
1154 This option allows user programs to put the CPU into V8086
1155 mode, which is an 80286-era approximation of 16-bit real mode.
1157 Some very old versions of X and/or vbetool require this option
1158 for user mode setting. Similarly, DOSEMU will use it if
1159 available to accelerate real mode DOS programs. However, any
1160 recent version of DOSEMU, X, or vbetool should be fully
1161 functional even without kernel VM86 support, as they will all
1162 fall back to software emulation. Nevertheless, if you are using
1163 a 16-bit DOS program where 16-bit performance matters, vm86
1164 mode might be faster than emulation and you might want to
1167 Note that any app that works on a 64-bit kernel is unlikely to
1168 need this option, as 64-bit kernels don't, and can't, support
1169 V8086 mode. This option is also unrelated to 16-bit protected
1170 mode and is not needed to run most 16-bit programs under Wine.
1172 Enabling this option increases the complexity of the kernel
1173 and slows down exception handling a tiny bit.
1175 If unsure, say N here.
1179 default X86_LEGACY_VM86
1182 bool "Enable support for 16-bit segments" if EXPERT
1184 depends on MODIFY_LDT_SYSCALL
1186 This option is required by programs like Wine to run 16-bit
1187 protected mode legacy code on x86 processors. Disabling
1188 this option saves about 300 bytes on i386, or around 6K text
1189 plus 16K runtime memory on x86-64,
1193 depends on X86_16BIT && X86_32
1197 depends on X86_16BIT && X86_64
1199 config X86_VSYSCALL_EMULATION
1200 bool "Enable vsyscall emulation" if EXPERT
1204 This enables emulation of the legacy vsyscall page. Disabling
1205 it is roughly equivalent to booting with vsyscall=none, except
1206 that it will also disable the helpful warning if a program
1207 tries to use a vsyscall. With this option set to N, offending
1208 programs will just segfault, citing addresses of the form
1211 This option is required by many programs built before 2013, and
1212 care should be used even with newer programs if set to N.
1214 Disabling this option saves about 7K of kernel size and
1215 possibly 4K of additional runtime pagetable memory.
1217 config X86_IOPL_IOPERM
1218 bool "IOPERM and IOPL Emulation"
1221 This enables the ioperm() and iopl() syscalls which are necessary
1222 for legacy applications.
1224 Legacy IOPL support is an overbroad mechanism which allows user
1225 space aside of accessing all 65536 I/O ports also to disable
1226 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1227 capabilities and permission from potentially active security
1230 The emulation restricts the functionality of the syscall to
1231 only allowing the full range I/O port access, but prevents the
1232 ability to disable interrupts from user space which would be
1233 granted if the hardware IOPL mechanism would be used.
1236 tristate "Toshiba Laptop support"
1239 This adds a driver to safely access the System Management Mode of
1240 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1241 not work on models with a Phoenix BIOS. The System Management Mode
1242 is used to set the BIOS and power saving options on Toshiba portables.
1244 For information on utilities to make use of this driver see the
1245 Toshiba Linux utilities web site at:
1246 <http://www.buzzard.org.uk/toshiba/>.
1248 Say Y if you intend to run this kernel on a Toshiba portable.
1252 tristate "Dell i8k legacy laptop support"
1254 select SENSORS_DELL_SMM
1256 This option enables legacy /proc/i8k userspace interface in hwmon
1257 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1258 temperature and allows controlling fan speeds of Dell laptops via
1259 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1260 it reports also power and hotkey status. For fan speed control is
1261 needed userspace package i8kutils.
1263 Say Y if you intend to run this kernel on old Dell laptops or want to
1264 use userspace package i8kutils.
1267 config X86_REBOOTFIXUPS
1268 bool "Enable X86 board specific fixups for reboot"
1271 This enables chipset and/or board specific fixups to be done
1272 in order to get reboot to work correctly. This is only needed on
1273 some combinations of hardware and BIOS. The symptom, for which
1274 this config is intended, is when reboot ends with a stalled/hung
1277 Currently, the only fixup is for the Geode machines using
1278 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1280 Say Y if you want to enable the fixup. Currently, it's safe to
1281 enable this option even if you don't need it.
1285 bool "CPU microcode loading support"
1287 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1289 If you say Y here, you will be able to update the microcode on
1290 Intel and AMD processors. The Intel support is for the IA32 family,
1291 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1292 AMD support is for families 0x10 and later. You will obviously need
1293 the actual microcode binary data itself which is not shipped with
1296 The preferred method to load microcode from a detached initrd is described
1297 in Documentation/x86/microcode.rst. For that you need to enable
1298 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1299 initrd for microcode blobs.
1301 In addition, you can build the microcode into the kernel. For that you
1302 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1305 config MICROCODE_INTEL
1306 bool "Intel microcode loading support"
1307 depends on MICROCODE
1310 This options enables microcode patch loading support for Intel
1313 For the current Intel microcode data package go to
1314 <https://downloadcenter.intel.com> and search for
1315 'Linux Processor Microcode Data File'.
1317 config MICROCODE_AMD
1318 bool "AMD microcode loading support"
1319 depends on MICROCODE
1321 If you select this option, microcode patch loading support for AMD
1322 processors will be enabled.
1324 config MICROCODE_OLD_INTERFACE
1325 bool "Ancient loading interface (DEPRECATED)"
1327 depends on MICROCODE
1329 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1330 which was used by userspace tools like iucode_tool and microcode.ctl.
1331 It is inadequate because it runs too late to be able to properly
1332 load microcode on a machine and it needs special tools. Instead, you
1333 should've switched to the early loading method with the initrd or
1334 builtin microcode by now: Documentation/x86/microcode.rst
1337 tristate "/dev/cpu/*/msr - Model-specific register support"
1339 This device gives privileged processes access to the x86
1340 Model-Specific Registers (MSRs). It is a character device with
1341 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1342 MSR accesses are directed to a specific CPU on multi-processor
1346 tristate "/dev/cpu/*/cpuid - CPU information support"
1348 This device gives processes access to the x86 CPUID instruction to
1349 be executed on a specific processor. It is a character device
1350 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1354 prompt "High Memory Support"
1361 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1362 However, the address space of 32-bit x86 processors is only 4
1363 Gigabytes large. That means that, if you have a large amount of
1364 physical memory, not all of it can be "permanently mapped" by the
1365 kernel. The physical memory that's not permanently mapped is called
1368 If you are compiling a kernel which will never run on a machine with
1369 more than 1 Gigabyte total physical RAM, answer "off" here (default
1370 choice and suitable for most users). This will result in a "3GB/1GB"
1371 split: 3GB are mapped so that each process sees a 3GB virtual memory
1372 space and the remaining part of the 4GB virtual memory space is used
1373 by the kernel to permanently map as much physical memory as
1376 If the machine has between 1 and 4 Gigabytes physical RAM, then
1379 If more than 4 Gigabytes is used then answer "64GB" here. This
1380 selection turns Intel PAE (Physical Address Extension) mode on.
1381 PAE implements 3-level paging on IA32 processors. PAE is fully
1382 supported by Linux, PAE mode is implemented on all recent Intel
1383 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1384 then the kernel will not boot on CPUs that don't support PAE!
1386 The actual amount of total physical memory will either be
1387 auto detected or can be forced by using a kernel command line option
1388 such as "mem=256M". (Try "man bootparam" or see the documentation of
1389 your boot loader (lilo or loadlin) about how to pass options to the
1390 kernel at boot time.)
1392 If unsure, say "off".
1397 Select this if you have a 32-bit processor and between 1 and 4
1398 gigabytes of physical RAM.
1402 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1405 Select this if you have a 32-bit processor and more than 4
1406 gigabytes of physical RAM.
1411 prompt "Memory split" if EXPERT
1415 Select the desired split between kernel and user memory.
1417 If the address range available to the kernel is less than the
1418 physical memory installed, the remaining memory will be available
1419 as "high memory". Accessing high memory is a little more costly
1420 than low memory, as it needs to be mapped into the kernel first.
1421 Note that increasing the kernel address space limits the range
1422 available to user programs, making the address space there
1423 tighter. Selecting anything other than the default 3G/1G split
1424 will also likely make your kernel incompatible with binary-only
1427 If you are not absolutely sure what you are doing, leave this
1431 bool "3G/1G user/kernel split"
1432 config VMSPLIT_3G_OPT
1434 bool "3G/1G user/kernel split (for full 1G low memory)"
1436 bool "2G/2G user/kernel split"
1437 config VMSPLIT_2G_OPT
1439 bool "2G/2G user/kernel split (for full 2G low memory)"
1441 bool "1G/3G user/kernel split"
1446 default 0xB0000000 if VMSPLIT_3G_OPT
1447 default 0x80000000 if VMSPLIT_2G
1448 default 0x78000000 if VMSPLIT_2G_OPT
1449 default 0x40000000 if VMSPLIT_1G
1455 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1458 bool "PAE (Physical Address Extension) Support"
1459 depends on X86_32 && !HIGHMEM4G
1460 select PHYS_ADDR_T_64BIT
1463 PAE is required for NX support, and furthermore enables
1464 larger swapspace support for non-overcommit purposes. It
1465 has the cost of more pagetable lookup overhead, and also
1466 consumes more pagetable space per process.
1469 bool "Enable 5-level page tables support"
1471 select DYNAMIC_MEMORY_LAYOUT
1472 select SPARSEMEM_VMEMMAP
1475 5-level paging enables access to larger address space:
1476 upto 128 PiB of virtual address space and 4 PiB of
1477 physical address space.
1479 It will be supported by future Intel CPUs.
1481 A kernel with the option enabled can be booted on machines that
1482 support 4- or 5-level paging.
1484 See Documentation/x86/x86_64/5level-paging.rst for more
1489 config X86_DIRECT_GBPAGES
1493 Certain kernel features effectively disable kernel
1494 linear 1 GB mappings (even if the CPU otherwise
1495 supports them), so don't confuse the user by printing
1496 that we have them enabled.
1498 config X86_CPA_STATISTICS
1499 bool "Enable statistic for Change Page Attribute"
1502 Expose statistics about the Change Page Attribute mechanism, which
1503 helps to determine the effectiveness of preserving large and huge
1504 page mappings when mapping protections are changed.
1506 config AMD_MEM_ENCRYPT
1507 bool "AMD Secure Memory Encryption (SME) support"
1508 depends on X86_64 && CPU_SUP_AMD
1509 select DMA_COHERENT_POOL
1510 select DYNAMIC_PHYSICAL_MASK
1511 select ARCH_USE_MEMREMAP_PROT
1512 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1513 select INSTRUCTION_DECODER
1514 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1516 Say yes to enable support for the encryption of system memory.
1517 This requires an AMD processor that supports Secure Memory
1520 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1521 bool "Activate AMD Secure Memory Encryption (SME) by default"
1523 depends on AMD_MEM_ENCRYPT
1525 Say yes to have system memory encrypted by default if running on
1526 an AMD processor that supports Secure Memory Encryption (SME).
1528 If set to Y, then the encryption of system memory can be
1529 deactivated with the mem_encrypt=off command line option.
1531 If set to N, then the encryption of system memory can be
1532 activated with the mem_encrypt=on command line option.
1534 # Common NUMA Features
1536 bool "NUMA Memory Allocation and Scheduler Support"
1538 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1539 default y if X86_BIGSMP
1541 Enable NUMA (Non-Uniform Memory Access) support.
1543 The kernel will try to allocate memory used by a CPU on the
1544 local memory controller of the CPU and add some more
1545 NUMA awareness to the kernel.
1547 For 64-bit this is recommended if the system is Intel Core i7
1548 (or later), AMD Opteron, or EM64T NUMA.
1550 For 32-bit this is only needed if you boot a 32-bit
1551 kernel on a 64-bit NUMA platform.
1553 Otherwise, you should say N.
1557 prompt "Old style AMD Opteron NUMA detection"
1558 depends on X86_64 && NUMA && PCI
1560 Enable AMD NUMA node topology detection. You should say Y here if
1561 you have a multi processor AMD system. This uses an old method to
1562 read the NUMA configuration directly from the builtin Northbridge
1563 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1564 which also takes priority if both are compiled in.
1566 config X86_64_ACPI_NUMA
1568 prompt "ACPI NUMA detection"
1569 depends on X86_64 && NUMA && ACPI && PCI
1572 Enable ACPI SRAT based node topology detection.
1575 bool "NUMA emulation"
1578 Enable NUMA emulation. A flat machine will be split
1579 into virtual nodes when booted with "numa=fake=N", where N is the
1580 number of nodes. This is only useful for debugging.
1583 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1585 default "10" if MAXSMP
1586 default "6" if X86_64
1590 Specify the maximum number of NUMA Nodes available on the target
1591 system. Increases memory reserved to accommodate various tables.
1593 config ARCH_FLATMEM_ENABLE
1595 depends on X86_32 && !NUMA
1597 config ARCH_SPARSEMEM_ENABLE
1599 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1600 select SPARSEMEM_STATIC if X86_32
1601 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1603 config ARCH_SPARSEMEM_DEFAULT
1604 def_bool X86_64 || (NUMA && X86_32)
1606 config ARCH_SELECT_MEMORY_MODEL
1608 depends on ARCH_SPARSEMEM_ENABLE
1610 config ARCH_MEMORY_PROBE
1611 bool "Enable sysfs memory/probe interface"
1612 depends on X86_64 && MEMORY_HOTPLUG
1614 This option enables a sysfs memory/probe interface for testing.
1615 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1616 If you are unsure how to answer this question, answer N.
1618 config ARCH_PROC_KCORE_TEXT
1620 depends on X86_64 && PROC_KCORE
1622 config ILLEGAL_POINTER_VALUE
1625 default 0xdead000000000000 if X86_64
1627 config X86_PMEM_LEGACY_DEVICE
1630 config X86_PMEM_LEGACY
1631 tristate "Support non-standard NVDIMMs and ADR protected memory"
1632 depends on PHYS_ADDR_T_64BIT
1634 select X86_PMEM_LEGACY_DEVICE
1635 select NUMA_KEEP_MEMINFO if NUMA
1638 Treat memory marked using the non-standard e820 type of 12 as used
1639 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1640 The kernel will offer these regions to the 'pmem' driver so
1641 they can be used for persistent storage.
1646 bool "Allocate 3rd-level pagetables from highmem"
1649 The VM uses one page table entry for each page of physical memory.
1650 For systems with a lot of RAM, this can be wasteful of precious
1651 low memory. Setting this option will put user-space page table
1652 entries in high memory.
1654 config X86_CHECK_BIOS_CORRUPTION
1655 bool "Check for low memory corruption"
1657 Periodically check for memory corruption in low memory, which
1658 is suspected to be caused by BIOS. Even when enabled in the
1659 configuration, it is disabled at runtime. Enable it by
1660 setting "memory_corruption_check=1" on the kernel command
1661 line. By default it scans the low 64k of memory every 60
1662 seconds; see the memory_corruption_check_size and
1663 memory_corruption_check_period parameters in
1664 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1666 When enabled with the default parameters, this option has
1667 almost no overhead, as it reserves a relatively small amount
1668 of memory and scans it infrequently. It both detects corruption
1669 and prevents it from affecting the running system.
1671 It is, however, intended as a diagnostic tool; if repeatable
1672 BIOS-originated corruption always affects the same memory,
1673 you can use memmap= to prevent the kernel from using that
1676 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1677 bool "Set the default setting of memory_corruption_check"
1678 depends on X86_CHECK_BIOS_CORRUPTION
1681 Set whether the default state of memory_corruption_check is
1684 config MATH_EMULATION
1686 depends on MODIFY_LDT_SYSCALL
1687 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1689 Linux can emulate a math coprocessor (used for floating point
1690 operations) if you don't have one. 486DX and Pentium processors have
1691 a math coprocessor built in, 486SX and 386 do not, unless you added
1692 a 487DX or 387, respectively. (The messages during boot time can
1693 give you some hints here ["man dmesg"].) Everyone needs either a
1694 coprocessor or this emulation.
1696 If you don't have a math coprocessor, you need to say Y here; if you
1697 say Y here even though you have a coprocessor, the coprocessor will
1698 be used nevertheless. (This behavior can be changed with the kernel
1699 command line option "no387", which comes handy if your coprocessor
1700 is broken. Try "man bootparam" or see the documentation of your boot
1701 loader (lilo or loadlin) about how to pass options to the kernel at
1702 boot time.) This means that it is a good idea to say Y here if you
1703 intend to use this kernel on different machines.
1705 More information about the internals of the Linux math coprocessor
1706 emulation can be found in <file:arch/x86/math-emu/README>.
1708 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1709 kernel, it won't hurt.
1713 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1715 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1716 the Memory Type Range Registers (MTRRs) may be used to control
1717 processor access to memory ranges. This is most useful if you have
1718 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1719 allows bus write transfers to be combined into a larger transfer
1720 before bursting over the PCI/AGP bus. This can increase performance
1721 of image write operations 2.5 times or more. Saying Y here creates a
1722 /proc/mtrr file which may be used to manipulate your processor's
1723 MTRRs. Typically the X server should use this.
1725 This code has a reasonably generic interface so that similar
1726 control registers on other processors can be easily supported
1729 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1730 Registers (ARRs) which provide a similar functionality to MTRRs. For
1731 these, the ARRs are used to emulate the MTRRs.
1732 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1733 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1734 write-combining. All of these processors are supported by this code
1735 and it makes sense to say Y here if you have one of them.
1737 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1738 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1739 can lead to all sorts of problems, so it's good to say Y here.
1741 You can safely say Y even if your machine doesn't have MTRRs, you'll
1742 just add about 9 KB to your kernel.
1744 See <file:Documentation/x86/mtrr.rst> for more information.
1746 config MTRR_SANITIZER
1748 prompt "MTRR cleanup support"
1751 Convert MTRR layout from continuous to discrete, so X drivers can
1752 add writeback entries.
1754 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1755 The largest mtrr entry size for a continuous block can be set with
1760 config MTRR_SANITIZER_ENABLE_DEFAULT
1761 int "MTRR cleanup enable value (0-1)"
1764 depends on MTRR_SANITIZER
1766 Enable mtrr cleanup default value
1768 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1769 int "MTRR cleanup spare reg num (0-7)"
1772 depends on MTRR_SANITIZER
1774 mtrr cleanup spare entries default, it can be changed via
1775 mtrr_spare_reg_nr=N on the kernel command line.
1779 prompt "x86 PAT support" if EXPERT
1782 Use PAT attributes to setup page level cache control.
1784 PATs are the modern equivalents of MTRRs and are much more
1785 flexible than MTRRs.
1787 Say N here if you see bootup problems (boot crash, boot hang,
1788 spontaneous reboots) or a non-working video driver.
1792 config ARCH_USES_PG_UNCACHED
1798 prompt "x86 architectural random number generator" if EXPERT
1800 Enable the x86 architectural RDRAND instruction
1801 (Intel Bull Mountain technology) to generate random numbers.
1802 If supported, this is a high bandwidth, cryptographically
1803 secure hardware random number generator.
1807 prompt "Supervisor Mode Access Prevention" if EXPERT
1809 Supervisor Mode Access Prevention (SMAP) is a security
1810 feature in newer Intel processors. There is a small
1811 performance cost if this enabled and turned on; there is
1812 also a small increase in the kernel size if this is enabled.
1818 prompt "User Mode Instruction Prevention" if EXPERT
1820 User Mode Instruction Prevention (UMIP) is a security feature in
1821 some x86 processors. If enabled, a general protection fault is
1822 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1823 executed in user mode. These instructions unnecessarily expose
1824 information about the hardware state.
1826 The vast majority of applications do not use these instructions.
1827 For the very few that do, software emulation is provided in
1828 specific cases in protected and virtual-8086 modes. Emulated
1831 config X86_INTEL_MEMORY_PROTECTION_KEYS
1832 prompt "Memory Protection Keys"
1834 # Note: only available in 64-bit mode
1835 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1836 select ARCH_USES_HIGH_VMA_FLAGS
1837 select ARCH_HAS_PKEYS
1839 Memory Protection Keys provides a mechanism for enforcing
1840 page-based protections, but without requiring modification of the
1841 page tables when an application changes protection domains.
1843 For details, see Documentation/core-api/protection-keys.rst
1848 prompt "TSX enable mode"
1849 depends on CPU_SUP_INTEL
1850 default X86_INTEL_TSX_MODE_OFF
1852 Intel's TSX (Transactional Synchronization Extensions) feature
1853 allows to optimize locking protocols through lock elision which
1854 can lead to a noticeable performance boost.
1856 On the other hand it has been shown that TSX can be exploited
1857 to form side channel attacks (e.g. TAA) and chances are there
1858 will be more of those attacks discovered in the future.
1860 Therefore TSX is not enabled by default (aka tsx=off). An admin
1861 might override this decision by tsx=on the command line parameter.
1862 Even with TSX enabled, the kernel will attempt to enable the best
1863 possible TAA mitigation setting depending on the microcode available
1864 for the particular machine.
1866 This option allows to set the default tsx mode between tsx=on, =off
1867 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1870 Say off if not sure, auto if TSX is in use but it should be used on safe
1871 platforms or on if TSX is in use and the security aspect of tsx is not
1874 config X86_INTEL_TSX_MODE_OFF
1877 TSX is disabled if possible - equals to tsx=off command line parameter.
1879 config X86_INTEL_TSX_MODE_ON
1882 TSX is always enabled on TSX capable HW - equals the tsx=on command
1885 config X86_INTEL_TSX_MODE_AUTO
1888 TSX is enabled on TSX capable HW that is believed to be safe against
1889 side channel attacks- equals the tsx=auto command line parameter.
1893 bool "Software Guard eXtensions (SGX)"
1894 depends on X86_64 && CPU_SUP_INTEL
1896 depends on CRYPTO_SHA256=y
1899 select NUMA_KEEP_MEMINFO if NUMA
1901 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1902 that can be used by applications to set aside private regions of code
1903 and data, referred to as enclaves. An enclave's private memory can
1904 only be accessed by code running within the enclave. Accesses from
1905 outside the enclave, including other enclaves, are disallowed by
1911 bool "EFI runtime service support"
1914 select EFI_RUNTIME_WRAPPERS
1916 This enables the kernel to use EFI runtime services that are
1917 available (such as the EFI variable services).
1919 This option is only useful on systems that have EFI firmware.
1920 In addition, you should use the latest ELILO loader available
1921 at <http://elilo.sourceforge.net> in order to take advantage
1922 of EFI runtime services. However, even with this option, the
1923 resultant kernel should continue to boot on existing non-EFI
1927 bool "EFI stub support"
1928 depends on EFI && !X86_USE_3DNOW
1929 depends on $(cc-option,-mabi=ms) || X86_32
1932 This kernel feature allows a bzImage to be loaded directly
1933 by EFI firmware without the use of a bootloader.
1935 See Documentation/admin-guide/efi-stub.rst for more information.
1938 bool "EFI mixed-mode support"
1939 depends on EFI_STUB && X86_64
1941 Enabling this feature allows a 64-bit kernel to be booted
1942 on a 32-bit firmware, provided that your CPU supports 64-bit
1945 Note that it is not possible to boot a mixed-mode enabled
1946 kernel via the EFI boot stub - a bootloader that supports
1947 the EFI handover protocol must be used.
1951 source "kernel/Kconfig.hz"
1954 bool "kexec system call"
1957 kexec is a system call that implements the ability to shutdown your
1958 current kernel, and to start another kernel. It is like a reboot
1959 but it is independent of the system firmware. And like a reboot
1960 you can start any kernel with it, not just Linux.
1962 The name comes from the similarity to the exec system call.
1964 It is an ongoing process to be certain the hardware in a machine
1965 is properly shutdown, so do not be surprised if this code does not
1966 initially work for you. As of this writing the exact hardware
1967 interface is strongly in flux, so no good recommendation can be
1971 bool "kexec file based system call"
1976 depends on CRYPTO_SHA256=y
1978 This is new version of kexec system call. This system call is
1979 file based and takes file descriptors as system call argument
1980 for kernel and initramfs as opposed to list of segments as
1981 accepted by previous system call.
1983 config ARCH_HAS_KEXEC_PURGATORY
1987 bool "Verify kernel signature during kexec_file_load() syscall"
1988 depends on KEXEC_FILE
1991 This option makes the kexec_file_load() syscall check for a valid
1992 signature of the kernel image. The image can still be loaded without
1993 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
1994 there's a signature that we can check, then it must be valid.
1996 In addition to this option, you need to enable signature
1997 verification for the corresponding kernel image type being
1998 loaded in order for this to work.
2000 config KEXEC_SIG_FORCE
2001 bool "Require a valid signature in kexec_file_load() syscall"
2002 depends on KEXEC_SIG
2004 This option makes kernel signature verification mandatory for
2005 the kexec_file_load() syscall.
2007 config KEXEC_BZIMAGE_VERIFY_SIG
2008 bool "Enable bzImage signature verification support"
2009 depends on KEXEC_SIG
2010 depends on SIGNED_PE_FILE_VERIFICATION
2011 select SYSTEM_TRUSTED_KEYRING
2013 Enable bzImage signature verification support.
2016 bool "kernel crash dumps"
2017 depends on X86_64 || (X86_32 && HIGHMEM)
2019 Generate crash dump after being started by kexec.
2020 This should be normally only set in special crash dump kernels
2021 which are loaded in the main kernel with kexec-tools into
2022 a specially reserved region and then later executed after
2023 a crash by kdump/kexec. The crash dump kernel must be compiled
2024 to a memory address not used by the main kernel or BIOS using
2025 PHYSICAL_START, or it must be built as a relocatable image
2026 (CONFIG_RELOCATABLE=y).
2027 For more details see Documentation/admin-guide/kdump/kdump.rst
2031 depends on KEXEC && HIBERNATION
2033 Jump between original kernel and kexeced kernel and invoke
2034 code in physical address mode via KEXEC
2036 config PHYSICAL_START
2037 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2040 This gives the physical address where the kernel is loaded.
2042 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2043 bzImage will decompress itself to above physical address and
2044 run from there. Otherwise, bzImage will run from the address where
2045 it has been loaded by the boot loader and will ignore above physical
2048 In normal kdump cases one does not have to set/change this option
2049 as now bzImage can be compiled as a completely relocatable image
2050 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2051 address. This option is mainly useful for the folks who don't want
2052 to use a bzImage for capturing the crash dump and want to use a
2053 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2054 to be specifically compiled to run from a specific memory area
2055 (normally a reserved region) and this option comes handy.
2057 So if you are using bzImage for capturing the crash dump,
2058 leave the value here unchanged to 0x1000000 and set
2059 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2060 for capturing the crash dump change this value to start of
2061 the reserved region. In other words, it can be set based on
2062 the "X" value as specified in the "crashkernel=YM@XM"
2063 command line boot parameter passed to the panic-ed
2064 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2065 for more details about crash dumps.
2067 Usage of bzImage for capturing the crash dump is recommended as
2068 one does not have to build two kernels. Same kernel can be used
2069 as production kernel and capture kernel. Above option should have
2070 gone away after relocatable bzImage support is introduced. But it
2071 is present because there are users out there who continue to use
2072 vmlinux for dump capture. This option should go away down the
2075 Don't change this unless you know what you are doing.
2078 bool "Build a relocatable kernel"
2081 This builds a kernel image that retains relocation information
2082 so it can be loaded someplace besides the default 1MB.
2083 The relocations tend to make the kernel binary about 10% larger,
2084 but are discarded at runtime.
2086 One use is for the kexec on panic case where the recovery kernel
2087 must live at a different physical address than the primary
2090 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2091 it has been loaded at and the compile time physical address
2092 (CONFIG_PHYSICAL_START) is used as the minimum location.
2094 config RANDOMIZE_BASE
2095 bool "Randomize the address of the kernel image (KASLR)"
2096 depends on RELOCATABLE
2099 In support of Kernel Address Space Layout Randomization (KASLR),
2100 this randomizes the physical address at which the kernel image
2101 is decompressed and the virtual address where the kernel
2102 image is mapped, as a security feature that deters exploit
2103 attempts relying on knowledge of the location of kernel
2106 On 64-bit, the kernel physical and virtual addresses are
2107 randomized separately. The physical address will be anywhere
2108 between 16MB and the top of physical memory (up to 64TB). The
2109 virtual address will be randomized from 16MB up to 1GB (9 bits
2110 of entropy). Note that this also reduces the memory space
2111 available to kernel modules from 1.5GB to 1GB.
2113 On 32-bit, the kernel physical and virtual addresses are
2114 randomized together. They will be randomized from 16MB up to
2115 512MB (8 bits of entropy).
2117 Entropy is generated using the RDRAND instruction if it is
2118 supported. If RDTSC is supported, its value is mixed into
2119 the entropy pool as well. If neither RDRAND nor RDTSC are
2120 supported, then entropy is read from the i8254 timer. The
2121 usable entropy is limited by the kernel being built using
2122 2GB addressing, and that PHYSICAL_ALIGN must be at a
2123 minimum of 2MB. As a result, only 10 bits of entropy are
2124 theoretically possible, but the implementations are further
2125 limited due to memory layouts.
2129 # Relocation on x86 needs some additional build support
2130 config X86_NEED_RELOCS
2132 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2134 config PHYSICAL_ALIGN
2135 hex "Alignment value to which kernel should be aligned"
2137 range 0x2000 0x1000000 if X86_32
2138 range 0x200000 0x1000000 if X86_64
2140 This value puts the alignment restrictions on physical address
2141 where kernel is loaded and run from. Kernel is compiled for an
2142 address which meets above alignment restriction.
2144 If bootloader loads the kernel at a non-aligned address and
2145 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2146 address aligned to above value and run from there.
2148 If bootloader loads the kernel at a non-aligned address and
2149 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2150 load address and decompress itself to the address it has been
2151 compiled for and run from there. The address for which kernel is
2152 compiled already meets above alignment restrictions. Hence the
2153 end result is that kernel runs from a physical address meeting
2154 above alignment restrictions.
2156 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2157 this value must be a multiple of 0x200000.
2159 Don't change this unless you know what you are doing.
2161 config DYNAMIC_MEMORY_LAYOUT
2164 This option makes base addresses of vmalloc and vmemmap as well as
2165 __PAGE_OFFSET movable during boot.
2167 config RANDOMIZE_MEMORY
2168 bool "Randomize the kernel memory sections"
2170 depends on RANDOMIZE_BASE
2171 select DYNAMIC_MEMORY_LAYOUT
2172 default RANDOMIZE_BASE
2174 Randomizes the base virtual address of kernel memory sections
2175 (physical memory mapping, vmalloc & vmemmap). This security feature
2176 makes exploits relying on predictable memory locations less reliable.
2178 The order of allocations remains unchanged. Entropy is generated in
2179 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2180 configuration have in average 30,000 different possible virtual
2181 addresses for each memory section.
2185 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2186 hex "Physical memory mapping padding" if EXPERT
2187 depends on RANDOMIZE_MEMORY
2188 default "0xa" if MEMORY_HOTPLUG
2190 range 0x1 0x40 if MEMORY_HOTPLUG
2193 Define the padding in terabytes added to the existing physical
2194 memory size during kernel memory randomization. It is useful
2195 for memory hotplug support but reduces the entropy available for
2196 address randomization.
2198 If unsure, leave at the default value.
2204 config BOOTPARAM_HOTPLUG_CPU0
2205 bool "Set default setting of cpu0_hotpluggable"
2206 depends on HOTPLUG_CPU
2208 Set whether default state of cpu0_hotpluggable is on or off.
2210 Say Y here to enable CPU0 hotplug by default. If this switch
2211 is turned on, there is no need to give cpu0_hotplug kernel
2212 parameter and the CPU0 hotplug feature is enabled by default.
2214 Please note: there are two known CPU0 dependencies if you want
2215 to enable the CPU0 hotplug feature either by this switch or by
2216 cpu0_hotplug kernel parameter.
2218 First, resume from hibernate or suspend always starts from CPU0.
2219 So hibernate and suspend are prevented if CPU0 is offline.
2221 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2222 offline if any interrupt can not migrate out of CPU0. There may
2223 be other CPU0 dependencies.
2225 Please make sure the dependencies are under your control before
2226 you enable this feature.
2228 Say N if you don't want to enable CPU0 hotplug feature by default.
2229 You still can enable the CPU0 hotplug feature at boot by kernel
2230 parameter cpu0_hotplug.
2232 config DEBUG_HOTPLUG_CPU0
2234 prompt "Debug CPU0 hotplug"
2235 depends on HOTPLUG_CPU
2237 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2238 soon as possible and boots up userspace with CPU0 offlined. User
2239 can online CPU0 back after boot time.
2241 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2242 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2243 compilation or giving cpu0_hotplug kernel parameter at boot.
2249 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2250 depends on COMPAT_32
2252 Certain buggy versions of glibc will crash if they are
2253 presented with a 32-bit vDSO that is not mapped at the address
2254 indicated in its segment table.
2256 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2257 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2258 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2259 the only released version with the bug, but OpenSUSE 9
2260 contains a buggy "glibc 2.3.2".
2262 The symptom of the bug is that everything crashes on startup, saying:
2263 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2265 Saying Y here changes the default value of the vdso32 boot
2266 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2267 This works around the glibc bug but hurts performance.
2269 If unsure, say N: if you are compiling your own kernel, you
2270 are unlikely to be using a buggy version of glibc.
2273 prompt "vsyscall table for legacy applications"
2275 default LEGACY_VSYSCALL_XONLY
2277 Legacy user code that does not know how to find the vDSO expects
2278 to be able to issue three syscalls by calling fixed addresses in
2279 kernel space. Since this location is not randomized with ASLR,
2280 it can be used to assist security vulnerability exploitation.
2282 This setting can be changed at boot time via the kernel command
2283 line parameter vsyscall=[emulate|xonly|none].
2285 On a system with recent enough glibc (2.14 or newer) and no
2286 static binaries, you can say None without a performance penalty
2287 to improve security.
2289 If unsure, select "Emulate execution only".
2291 config LEGACY_VSYSCALL_EMULATE
2292 bool "Full emulation"
2294 The kernel traps and emulates calls into the fixed vsyscall
2295 address mapping. This makes the mapping non-executable, but
2296 it still contains readable known contents, which could be
2297 used in certain rare security vulnerability exploits. This
2298 configuration is recommended when using legacy userspace
2299 that still uses vsyscalls along with legacy binary
2300 instrumentation tools that require code to be readable.
2302 An example of this type of legacy userspace is running
2303 Pin on an old binary that still uses vsyscalls.
2305 config LEGACY_VSYSCALL_XONLY
2306 bool "Emulate execution only"
2308 The kernel traps and emulates calls into the fixed vsyscall
2309 address mapping and does not allow reads. This
2310 configuration is recommended when userspace might use the
2311 legacy vsyscall area but support for legacy binary
2312 instrumentation of legacy code is not needed. It mitigates
2313 certain uses of the vsyscall area as an ASLR-bypassing
2316 config LEGACY_VSYSCALL_NONE
2319 There will be no vsyscall mapping at all. This will
2320 eliminate any risk of ASLR bypass due to the vsyscall
2321 fixed address mapping. Attempts to use the vsyscalls
2322 will be reported to dmesg, so that either old or
2323 malicious userspace programs can be identified.
2328 bool "Built-in kernel command line"
2330 Allow for specifying boot arguments to the kernel at
2331 build time. On some systems (e.g. embedded ones), it is
2332 necessary or convenient to provide some or all of the
2333 kernel boot arguments with the kernel itself (that is,
2334 to not rely on the boot loader to provide them.)
2336 To compile command line arguments into the kernel,
2337 set this option to 'Y', then fill in the
2338 boot arguments in CONFIG_CMDLINE.
2340 Systems with fully functional boot loaders (i.e. non-embedded)
2341 should leave this option set to 'N'.
2344 string "Built-in kernel command string"
2345 depends on CMDLINE_BOOL
2348 Enter arguments here that should be compiled into the kernel
2349 image and used at boot time. If the boot loader provides a
2350 command line at boot time, it is appended to this string to
2351 form the full kernel command line, when the system boots.
2353 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2354 change this behavior.
2356 In most cases, the command line (whether built-in or provided
2357 by the boot loader) should specify the device for the root
2360 config CMDLINE_OVERRIDE
2361 bool "Built-in command line overrides boot loader arguments"
2362 depends on CMDLINE_BOOL && CMDLINE != ""
2364 Set this option to 'Y' to have the kernel ignore the boot loader
2365 command line, and use ONLY the built-in command line.
2367 This is used to work around broken boot loaders. This should
2368 be set to 'N' under normal conditions.
2370 config MODIFY_LDT_SYSCALL
2371 bool "Enable the LDT (local descriptor table)" if EXPERT
2374 Linux can allow user programs to install a per-process x86
2375 Local Descriptor Table (LDT) using the modify_ldt(2) system
2376 call. This is required to run 16-bit or segmented code such as
2377 DOSEMU or some Wine programs. It is also used by some very old
2378 threading libraries.
2380 Enabling this feature adds a small amount of overhead to
2381 context switches and increases the low-level kernel attack
2382 surface. Disabling it removes the modify_ldt(2) system call.
2384 Saying 'N' here may make sense for embedded or server kernels.
2386 source "kernel/livepatch/Kconfig"
2390 config ARCH_HAS_ADD_PAGES
2392 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2394 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2397 config USE_PERCPU_NUMA_NODE_ID
2401 menu "Power management and ACPI options"
2403 config ARCH_HIBERNATION_HEADER
2405 depends on HIBERNATION
2407 source "kernel/power/Kconfig"
2409 source "drivers/acpi/Kconfig"
2416 tristate "APM (Advanced Power Management) BIOS support"
2417 depends on X86_32 && PM_SLEEP
2419 APM is a BIOS specification for saving power using several different
2420 techniques. This is mostly useful for battery powered laptops with
2421 APM compliant BIOSes. If you say Y here, the system time will be
2422 reset after a RESUME operation, the /proc/apm device will provide
2423 battery status information, and user-space programs will receive
2424 notification of APM "events" (e.g. battery status change).
2426 If you select "Y" here, you can disable actual use of the APM
2427 BIOS by passing the "apm=off" option to the kernel at boot time.
2429 Note that the APM support is almost completely disabled for
2430 machines with more than one CPU.
2432 In order to use APM, you will need supporting software. For location
2433 and more information, read <file:Documentation/power/apm-acpi.rst>
2434 and the Battery Powered Linux mini-HOWTO, available from
2435 <http://www.tldp.org/docs.html#howto>.
2437 This driver does not spin down disk drives (see the hdparm(8)
2438 manpage ("man 8 hdparm") for that), and it doesn't turn off
2439 VESA-compliant "green" monitors.
2441 This driver does not support the TI 4000M TravelMate and the ACER
2442 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2443 desktop machines also don't have compliant BIOSes, and this driver
2444 may cause those machines to panic during the boot phase.
2446 Generally, if you don't have a battery in your machine, there isn't
2447 much point in using this driver and you should say N. If you get
2448 random kernel OOPSes or reboots that don't seem to be related to
2449 anything, try disabling/enabling this option (or disabling/enabling
2452 Some other things you should try when experiencing seemingly random,
2455 1) make sure that you have enough swap space and that it is
2457 2) pass the "no-hlt" option to the kernel
2458 3) switch on floating point emulation in the kernel and pass
2459 the "no387" option to the kernel
2460 4) pass the "floppy=nodma" option to the kernel
2461 5) pass the "mem=4M" option to the kernel (thereby disabling
2462 all but the first 4 MB of RAM)
2463 6) make sure that the CPU is not over clocked.
2464 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2465 8) disable the cache from your BIOS settings
2466 9) install a fan for the video card or exchange video RAM
2467 10) install a better fan for the CPU
2468 11) exchange RAM chips
2469 12) exchange the motherboard.
2471 To compile this driver as a module, choose M here: the
2472 module will be called apm.
2476 config APM_IGNORE_USER_SUSPEND
2477 bool "Ignore USER SUSPEND"
2479 This option will ignore USER SUSPEND requests. On machines with a
2480 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2481 series notebooks, it is necessary to say Y because of a BIOS bug.
2483 config APM_DO_ENABLE
2484 bool "Enable PM at boot time"
2486 Enable APM features at boot time. From page 36 of the APM BIOS
2487 specification: "When disabled, the APM BIOS does not automatically
2488 power manage devices, enter the Standby State, enter the Suspend
2489 State, or take power saving steps in response to CPU Idle calls."
2490 This driver will make CPU Idle calls when Linux is idle (unless this
2491 feature is turned off -- see "Do CPU IDLE calls", below). This
2492 should always save battery power, but more complicated APM features
2493 will be dependent on your BIOS implementation. You may need to turn
2494 this option off if your computer hangs at boot time when using APM
2495 support, or if it beeps continuously instead of suspending. Turn
2496 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2497 T400CDT. This is off by default since most machines do fine without
2502 bool "Make CPU Idle calls when idle"
2504 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2505 On some machines, this can activate improved power savings, such as
2506 a slowed CPU clock rate, when the machine is idle. These idle calls
2507 are made after the idle loop has run for some length of time (e.g.,
2508 333 mS). On some machines, this will cause a hang at boot time or
2509 whenever the CPU becomes idle. (On machines with more than one CPU,
2510 this option does nothing.)
2512 config APM_DISPLAY_BLANK
2513 bool "Enable console blanking using APM"
2515 Enable console blanking using the APM. Some laptops can use this to
2516 turn off the LCD backlight when the screen blanker of the Linux
2517 virtual console blanks the screen. Note that this is only used by
2518 the virtual console screen blanker, and won't turn off the backlight
2519 when using the X Window system. This also doesn't have anything to
2520 do with your VESA-compliant power-saving monitor. Further, this
2521 option doesn't work for all laptops -- it might not turn off your
2522 backlight at all, or it might print a lot of errors to the console,
2523 especially if you are using gpm.
2525 config APM_ALLOW_INTS
2526 bool "Allow interrupts during APM BIOS calls"
2528 Normally we disable external interrupts while we are making calls to
2529 the APM BIOS as a measure to lessen the effects of a badly behaving
2530 BIOS implementation. The BIOS should reenable interrupts if it
2531 needs to. Unfortunately, some BIOSes do not -- especially those in
2532 many of the newer IBM Thinkpads. If you experience hangs when you
2533 suspend, try setting this to Y. Otherwise, say N.
2537 source "drivers/cpufreq/Kconfig"
2539 source "drivers/cpuidle/Kconfig"
2541 source "drivers/idle/Kconfig"
2546 menu "Bus options (PCI etc.)"
2549 prompt "PCI access mode"
2550 depends on X86_32 && PCI
2553 On PCI systems, the BIOS can be used to detect the PCI devices and
2554 determine their configuration. However, some old PCI motherboards
2555 have BIOS bugs and may crash if this is done. Also, some embedded
2556 PCI-based systems don't have any BIOS at all. Linux can also try to
2557 detect the PCI hardware directly without using the BIOS.
2559 With this option, you can specify how Linux should detect the
2560 PCI devices. If you choose "BIOS", the BIOS will be used,
2561 if you choose "Direct", the BIOS won't be used, and if you
2562 choose "MMConfig", then PCI Express MMCONFIG will be used.
2563 If you choose "Any", the kernel will try MMCONFIG, then the
2564 direct access method and falls back to the BIOS if that doesn't
2565 work. If unsure, go with the default, which is "Any".
2570 config PCI_GOMMCONFIG
2587 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2589 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2592 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2595 bool "Support mmconfig PCI config space access" if X86_64
2597 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2598 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2602 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2606 depends on PCI && XEN
2609 config MMCONF_FAM10H
2611 depends on X86_64 && PCI_MMCONFIG && ACPI
2613 config PCI_CNB20LE_QUIRK
2614 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2617 Read the PCI windows out of the CNB20LE host bridge. This allows
2618 PCI hotplug to work on systems with the CNB20LE chipset which do
2621 There's no public spec for this chipset, and this functionality
2622 is known to be incomplete.
2624 You should say N unless you know you need this.
2627 bool "ISA bus support on modern systems" if EXPERT
2629 Expose ISA bus device drivers and options available for selection and
2630 configuration. Enable this option if your target machine has an ISA
2631 bus. ISA is an older system, displaced by PCI and newer bus
2632 architectures -- if your target machine is modern, it probably does
2633 not have an ISA bus.
2637 # x86_64 have no ISA slots, but can have ISA-style DMA.
2639 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2642 Enables ISA-style DMA support for devices requiring such controllers.
2650 Find out whether you have ISA slots on your motherboard. ISA is the
2651 name of a bus system, i.e. the way the CPU talks to the other stuff
2652 inside your box. Other bus systems are PCI, EISA, MicroChannel
2653 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2654 newer boards don't support it. If you have ISA, say Y, otherwise N.
2657 tristate "NatSemi SCx200 support"
2659 This provides basic support for National Semiconductor's
2660 (now AMD's) Geode processors. The driver probes for the
2661 PCI-IDs of several on-chip devices, so its a good dependency
2662 for other scx200_* drivers.
2664 If compiled as a module, the driver is named scx200.
2666 config SCx200HR_TIMER
2667 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2671 This driver provides a clocksource built upon the on-chip
2672 27MHz high-resolution timer. Its also a workaround for
2673 NSC Geode SC-1100's buggy TSC, which loses time when the
2674 processor goes idle (as is done by the scheduler). The
2675 other workaround is idle=poll boot option.
2678 bool "One Laptop Per Child support"
2686 Add support for detecting the unique features of the OLPC
2690 bool "OLPC XO-1 Power Management"
2691 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2693 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2696 bool "OLPC XO-1 Real Time Clock"
2697 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2699 Add support for the XO-1 real time clock, which can be used as a
2700 programmable wakeup source.
2703 bool "OLPC XO-1 SCI extras"
2704 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2708 Add support for SCI-based features of the OLPC XO-1 laptop:
2709 - EC-driven system wakeups
2713 - AC adapter status updates
2714 - Battery status updates
2716 config OLPC_XO15_SCI
2717 bool "OLPC XO-1.5 SCI extras"
2718 depends on OLPC && ACPI
2721 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2722 - EC-driven system wakeups
2723 - AC adapter status updates
2724 - Battery status updates
2727 bool "PCEngines ALIX System Support (LED setup)"
2730 This option enables system support for the PCEngines ALIX.
2731 At present this just sets up LEDs for GPIO control on
2732 ALIX2/3/6 boards. However, other system specific setup should
2735 Note: You must still enable the drivers for GPIO and LED support
2736 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2738 Note: You have to set alix.force=1 for boards with Award BIOS.
2741 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2744 This option enables system support for the Soekris Engineering net5501.
2747 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2751 This option enables system support for the Traverse Technologies GEOS.
2754 bool "Technologic Systems TS-5500 platform support"
2756 select CHECK_SIGNATURE
2760 This option enables system support for the Technologic Systems TS-5500.
2766 depends on CPU_SUP_AMD && PCI
2771 menu "Binary Emulations"
2773 config IA32_EMULATION
2774 bool "IA32 Emulation"
2776 select ARCH_WANT_OLD_COMPAT_IPC
2778 select COMPAT_OLD_SIGACTION
2780 Include code to run legacy 32-bit programs under a
2781 64-bit kernel. You should likely turn this on, unless you're
2782 100% sure that you don't have any 32-bit programs left.
2785 tristate "IA32 a.out support"
2786 depends on IA32_EMULATION
2789 Support old a.out binaries in the 32bit emulation.
2792 bool "x32 ABI for 64-bit mode"
2795 Include code to run binaries for the x32 native 32-bit ABI
2796 for 64-bit processors. An x32 process gets access to the
2797 full 64-bit register file and wide data path while leaving
2798 pointers at 32 bits for smaller memory footprint.
2800 You will need a recent binutils (2.22 or later) with
2801 elf32_x86_64 support enabled to compile a kernel with this
2806 depends on IA32_EMULATION || X86_32
2808 select OLD_SIGSUSPEND3
2812 depends on IA32_EMULATION || X86_X32
2815 config COMPAT_FOR_U64_ALIGNMENT
2818 config SYSVIPC_COMPAT
2826 config HAVE_ATOMIC_IOMAP
2830 source "drivers/firmware/Kconfig"
2832 source "arch/x86/kvm/Kconfig"
2834 source "arch/x86/Kconfig.assembler"