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_CORRECT_STACKTRACE_ON_KRETPROBE
65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
71 select ARCH_HAS_CACHE_LINE_SIZE
72 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
73 select ARCH_HAS_CURRENT_STACK_POINTER
74 select ARCH_HAS_DEBUG_VIRTUAL
75 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
76 select ARCH_HAS_DEVMEM_IS_ALLOWED
77 select ARCH_HAS_EARLY_DEBUG if KGDB
78 select ARCH_HAS_ELF_RANDOMIZE
79 select ARCH_HAS_FAST_MULTIPLIER
80 select ARCH_HAS_FORTIFY_SOURCE
81 select ARCH_HAS_GCOV_PROFILE_ALL
82 select ARCH_HAS_KCOV if X86_64
83 select ARCH_HAS_MEM_ENCRYPT
84 select ARCH_HAS_MEMBARRIER_SYNC_CORE
85 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
86 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
87 select ARCH_HAS_PMEM_API if X86_64
88 select ARCH_HAS_PTE_DEVMAP if X86_64
89 select ARCH_HAS_PTE_SPECIAL
90 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
91 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
92 select ARCH_HAS_COPY_MC if X86_64
93 select ARCH_HAS_SET_MEMORY
94 select ARCH_HAS_SET_DIRECT_MAP
95 select ARCH_HAS_STRICT_KERNEL_RWX
96 select ARCH_HAS_STRICT_MODULE_RWX
97 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
98 select ARCH_HAS_SYSCALL_WRAPPER
99 select ARCH_HAS_UBSAN_SANITIZE_ALL
100 select ARCH_HAS_DEBUG_WX
101 select ARCH_HAS_ZONE_DMA_SET if EXPERT
102 select ARCH_HAVE_NMI_SAFE_CMPXCHG
103 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
104 select ARCH_MIGHT_HAVE_PC_PARPORT
105 select ARCH_MIGHT_HAVE_PC_SERIO
106 select ARCH_STACKWALK
107 select ARCH_SUPPORTS_ACPI
108 select ARCH_SUPPORTS_ATOMIC_RMW
109 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
110 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
111 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
112 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
113 select ARCH_SUPPORTS_CFI_CLANG if X86_64
114 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
115 select ARCH_SUPPORTS_LTO_CLANG
116 select ARCH_SUPPORTS_LTO_CLANG_THIN
117 select ARCH_USE_BUILTIN_BSWAP
118 select ARCH_USE_MEMTEST
119 select ARCH_USE_QUEUED_RWLOCKS
120 select ARCH_USE_QUEUED_SPINLOCKS
121 select ARCH_USE_SYM_ANNOTATIONS
122 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
123 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
124 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
125 select ARCH_WANTS_NO_INSTR
126 select ARCH_WANT_GENERAL_HUGETLB
127 select ARCH_WANT_HUGE_PMD_SHARE
128 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
129 select ARCH_WANT_LD_ORPHAN_WARN
130 select ARCH_WANTS_THP_SWAP if X86_64
131 select ARCH_HAS_PARANOID_L1D_FLUSH
132 select BUILDTIME_TABLE_SORT
134 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
135 select CLOCKSOURCE_WATCHDOG
136 # Word-size accesses may read uninitialized data past the trailing \0
137 # in strings and cause false KMSAN reports.
138 select DCACHE_WORD_ACCESS if !KMSAN
139 select DYNAMIC_SIGFRAME
140 select EDAC_ATOMIC_SCRUB
142 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
143 select GENERIC_CLOCKEVENTS_MIN_ADJUST
144 select GENERIC_CMOS_UPDATE
145 select GENERIC_CPU_AUTOPROBE
146 select GENERIC_CPU_VULNERABILITIES
147 select GENERIC_EARLY_IOREMAP
150 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
151 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
152 select GENERIC_IRQ_MIGRATION if SMP
153 select GENERIC_IRQ_PROBE
154 select GENERIC_IRQ_RESERVATION_MODE
155 select GENERIC_IRQ_SHOW
156 select GENERIC_PENDING_IRQ if SMP
157 select GENERIC_PTDUMP
158 select GENERIC_SMP_IDLE_THREAD
159 select GENERIC_TIME_VSYSCALL
160 select GENERIC_GETTIMEOFDAY
161 select GENERIC_VDSO_TIME_NS
162 select GUP_GET_PXX_LOW_HIGH if X86_PAE
163 select HARDIRQS_SW_RESEND
164 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
166 select HAVE_ACPI_APEI if ACPI
167 select HAVE_ACPI_APEI_NMI if ACPI
168 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
169 select HAVE_ARCH_AUDITSYSCALL
170 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
171 select HAVE_ARCH_HUGE_VMALLOC if X86_64
172 select HAVE_ARCH_JUMP_LABEL
173 select HAVE_ARCH_JUMP_LABEL_RELATIVE
174 select HAVE_ARCH_KASAN if X86_64
175 select HAVE_ARCH_KASAN_VMALLOC if X86_64
176 select HAVE_ARCH_KFENCE
177 select HAVE_ARCH_KMSAN if X86_64
178 select HAVE_ARCH_KGDB
179 select HAVE_ARCH_MMAP_RND_BITS if MMU
180 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
181 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
182 select HAVE_ARCH_PREL32_RELOCATIONS
183 select HAVE_ARCH_SECCOMP_FILTER
184 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
185 select HAVE_ARCH_STACKLEAK
186 select HAVE_ARCH_TRACEHOOK
187 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
188 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
189 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
190 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
191 select HAVE_ARCH_VMAP_STACK if X86_64
192 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
193 select HAVE_ARCH_WITHIN_STACK_FRAMES
194 select HAVE_ASM_MODVERSIONS
195 select HAVE_CMPXCHG_DOUBLE
196 select HAVE_CMPXCHG_LOCAL
197 select HAVE_CONTEXT_TRACKING_USER if X86_64
198 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
199 select HAVE_C_RECORDMCOUNT
200 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
201 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
202 select HAVE_BUILDTIME_MCOUNT_SORT
203 select HAVE_DEBUG_KMEMLEAK
204 select HAVE_DMA_CONTIGUOUS
205 select HAVE_DYNAMIC_FTRACE
206 select HAVE_DYNAMIC_FTRACE_WITH_REGS
207 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
208 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
209 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
210 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
212 select HAVE_EFFICIENT_UNALIGNED_ACCESS
214 select HAVE_EXIT_THREAD
216 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
217 select HAVE_FTRACE_MCOUNT_RECORD
218 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
219 select HAVE_FUNCTION_TRACER
220 select HAVE_GCC_PLUGINS
221 select HAVE_HW_BREAKPOINT
222 select HAVE_IOREMAP_PROT
223 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
224 select HAVE_IRQ_TIME_ACCOUNTING
225 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
226 select HAVE_KERNEL_BZIP2
227 select HAVE_KERNEL_GZIP
228 select HAVE_KERNEL_LZ4
229 select HAVE_KERNEL_LZMA
230 select HAVE_KERNEL_LZO
231 select HAVE_KERNEL_XZ
232 select HAVE_KERNEL_ZSTD
234 select HAVE_KPROBES_ON_FTRACE
235 select HAVE_FUNCTION_ERROR_INJECTION
236 select HAVE_KRETPROBES
239 select HAVE_LIVEPATCH if X86_64
240 select HAVE_MIXED_BREAKPOINTS_REGS
241 select HAVE_MOD_ARCH_SPECIFIC
244 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
246 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
247 select HAVE_OBJTOOL if X86_64
248 select HAVE_OPTPROBES
249 select HAVE_PCSPKR_PLATFORM
250 select HAVE_PERF_EVENTS
251 select HAVE_PERF_EVENTS_NMI
252 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
254 select HAVE_PERF_REGS
255 select HAVE_PERF_USER_STACK_DUMP
256 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
257 select MMU_GATHER_MERGE_VMAS
258 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
259 select HAVE_REGS_AND_STACK_ACCESS_API
260 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
261 select HAVE_FUNCTION_ARG_ACCESS_API
262 select HAVE_SETUP_PER_CPU_AREA
263 select HAVE_SOFTIRQ_ON_OWN_STACK
264 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
265 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
266 select HAVE_STATIC_CALL
267 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
268 select HAVE_PREEMPT_DYNAMIC_CALL
270 select HAVE_RUST if X86_64
271 select HAVE_SYSCALL_TRACEPOINTS
272 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
273 select HAVE_UNSTABLE_SCHED_CLOCK
274 select HAVE_USER_RETURN_NOTIFIER
275 select HAVE_GENERIC_VDSO
276 select HOTPLUG_SMT if SMP
277 select IRQ_FORCED_THREADING
278 select NEED_PER_CPU_EMBED_FIRST_CHUNK
279 select NEED_PER_CPU_PAGE_FIRST_CHUNK
280 select NEED_SG_DMA_LENGTH
281 select PCI_DOMAINS if PCI
282 select PCI_LOCKLESS_CONFIG if PCI
285 select RTC_MC146818_LIB
287 select SYSCTL_EXCEPTION_TRACE
288 select THREAD_INFO_IN_TASK
289 select TRACE_IRQFLAGS_SUPPORT
290 select TRACE_IRQFLAGS_NMI_SUPPORT
291 select USER_STACKTRACE_SUPPORT
292 select HAVE_ARCH_KCSAN if X86_64
293 select X86_FEATURE_NAMES if PROC_FS
294 select PROC_PID_ARCH_STATUS if PROC_FS
295 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
296 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
297 select FUNCTION_ALIGNMENT_4B
298 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
299 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
301 config INSTRUCTION_DECODER
303 depends on KPROBES || PERF_EVENTS || UPROBES
307 default "elf32-i386" if X86_32
308 default "elf64-x86-64" if X86_64
310 config LOCKDEP_SUPPORT
313 config STACKTRACE_SUPPORT
319 config ARCH_MMAP_RND_BITS_MIN
323 config ARCH_MMAP_RND_BITS_MAX
327 config ARCH_MMAP_RND_COMPAT_BITS_MIN
330 config ARCH_MMAP_RND_COMPAT_BITS_MAX
336 config GENERIC_ISA_DMA
338 depends on ISA_DMA_API
342 default y if KMSAN || KASAN
347 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
349 config GENERIC_BUG_RELATIVE_POINTERS
352 config ARCH_MAY_HAVE_PC_FDC
354 depends on ISA_DMA_API
356 config GENERIC_CALIBRATE_DELAY
359 config ARCH_HAS_CPU_RELAX
362 config ARCH_HIBERNATION_POSSIBLE
365 config ARCH_SUSPEND_POSSIBLE
371 config KASAN_SHADOW_OFFSET
374 default 0xdffffc0000000000
376 config HAVE_INTEL_TXT
378 depends on INTEL_IOMMU && ACPI
382 depends on X86_32 && SMP
386 depends on X86_64 && SMP
388 config ARCH_SUPPORTS_UPROBES
391 config FIX_EARLYCON_MEM
394 config DYNAMIC_PHYSICAL_MASK
397 config PGTABLE_LEVELS
399 default 5 if X86_5LEVEL
404 config CC_HAS_SANE_STACKPROTECTOR
406 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
407 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
409 We have to make sure stack protector is unconditionally disabled if
410 the compiler produces broken code or if it does not let us control
411 the segment on 32-bit kernels.
413 menu "Processor type and features"
416 bool "Symmetric multi-processing support"
418 This enables support for systems with more than one CPU. If you have
419 a system with only one CPU, say N. If you have a system with more
422 If you say N here, the kernel will run on uni- and multiprocessor
423 machines, but will use only one CPU of a multiprocessor machine. If
424 you say Y here, the kernel will run on many, but not all,
425 uniprocessor machines. On a uniprocessor machine, the kernel
426 will run faster if you say N here.
428 Note that if you say Y here and choose architecture "586" or
429 "Pentium" under "Processor family", the kernel will not work on 486
430 architectures. Similarly, multiprocessor kernels for the "PPro"
431 architecture may not work on all Pentium based boards.
433 People using multiprocessor machines who say Y here should also say
434 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
435 Management" code will be disabled if you say Y here.
437 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
438 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
439 <http://www.tldp.org/docs.html#howto>.
441 If you don't know what to do here, say N.
443 config X86_FEATURE_NAMES
444 bool "Processor feature human-readable names" if EMBEDDED
447 This option compiles in a table of x86 feature bits and corresponding
448 names. This is required to support /proc/cpuinfo and a few kernel
449 messages. You can disable this to save space, at the expense of
450 making those few kernel messages show numeric feature bits instead.
455 bool "Support x2apic"
456 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
458 This enables x2apic support on CPUs that have this feature.
460 This allows 32-bit apic IDs (so it can support very large systems),
461 and accesses the local apic via MSRs not via mmio.
463 Some Intel systems circa 2022 and later are locked into x2APIC mode
464 and can not fall back to the legacy APIC modes if SGX or TDX are
465 enabled in the BIOS. They will boot with very reduced functionality
466 without enabling this option.
468 If you don't know what to do here, say N.
471 bool "Enable MPS table" if ACPI
473 depends on X86_LOCAL_APIC
475 For old smp systems that do not have proper acpi support. Newer systems
476 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
480 depends on X86_GOLDFISH
482 config X86_CPU_RESCTRL
483 bool "x86 CPU resource control support"
484 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
486 select PROC_CPU_RESCTRL if PROC_FS
488 Enable x86 CPU resource control support.
490 Provide support for the allocation and monitoring of system resources
493 Intel calls this Intel Resource Director Technology
494 (Intel(R) RDT). More information about RDT can be found in the
495 Intel x86 Architecture Software Developer Manual.
497 AMD calls this AMD Platform Quality of Service (AMD QoS).
498 More information about AMD QoS can be found in the AMD64 Technology
499 Platform Quality of Service Extensions manual.
505 bool "Support for big SMP systems with more than 8 CPUs"
508 This option is needed for the systems that have more than 8 CPUs.
510 config X86_EXTENDED_PLATFORM
511 bool "Support for extended (non-PC) x86 platforms"
514 If you disable this option then the kernel will only support
515 standard PC platforms. (which covers the vast majority of
518 If you enable this option then you'll be able to select support
519 for the following (non-PC) 32 bit x86 platforms:
520 Goldfish (Android emulator)
523 SGI 320/540 (Visual Workstation)
524 STA2X11-based (e.g. Northville)
525 Moorestown MID devices
527 If you have one of these systems, or if you want to build a
528 generic distribution kernel, say Y here - otherwise say N.
532 config X86_EXTENDED_PLATFORM
533 bool "Support for extended (non-PC) x86 platforms"
536 If you disable this option then the kernel will only support
537 standard PC platforms. (which covers the vast majority of
540 If you enable this option then you'll be able to select support
541 for the following (non-PC) 64 bit x86 platforms:
546 If you have one of these systems, or if you want to build a
547 generic distribution kernel, say Y here - otherwise say N.
549 # This is an alphabetically sorted list of 64 bit extended platforms
550 # Please maintain the alphabetic order if and when there are additions
552 bool "Numascale NumaChip"
554 depends on X86_EXTENDED_PLATFORM
557 depends on X86_X2APIC
558 depends on PCI_MMCONFIG
560 Adds support for Numascale NumaChip large-SMP systems. Needed to
561 enable more than ~168 cores.
562 If you don't have one of these, you should say N here.
566 select HYPERVISOR_GUEST
568 depends on X86_64 && PCI
569 depends on X86_EXTENDED_PLATFORM
572 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
573 supposed to run on these EM64T-based machines. Only choose this option
574 if you have one of these machines.
577 bool "SGI Ultraviolet"
579 depends on X86_EXTENDED_PLATFORM
582 depends on KEXEC_CORE
583 depends on X86_X2APIC
586 This option is needed in order to support SGI Ultraviolet systems.
587 If you don't have one of these, you should say N here.
589 # Following is an alphabetically sorted list of 32 bit extended platforms
590 # Please maintain the alphabetic order if and when there are additions
593 bool "Goldfish (Virtual Platform)"
594 depends on X86_EXTENDED_PLATFORM
596 Enable support for the Goldfish virtual platform used primarily
597 for Android development. Unless you are building for the Android
598 Goldfish emulator say N here.
601 bool "CE4100 TV platform"
603 depends on PCI_GODIRECT
604 depends on X86_IO_APIC
606 depends on X86_EXTENDED_PLATFORM
607 select X86_REBOOTFIXUPS
609 select OF_EARLY_FLATTREE
611 Select for the Intel CE media processor (CE4100) SOC.
612 This option compiles in support for the CE4100 SOC for settop
613 boxes and media devices.
616 bool "Intel MID platform support"
617 depends on X86_EXTENDED_PLATFORM
618 depends on X86_PLATFORM_DEVICES
620 depends on X86_64 || (PCI_GOANY && X86_32)
621 depends on X86_IO_APIC
626 Select to build a kernel capable of supporting Intel MID (Mobile
627 Internet Device) platform systems which do not have the PCI legacy
628 interfaces. If you are building for a PC class system say N here.
630 Intel MID platforms are based on an Intel processor and chipset which
631 consume less power than most of the x86 derivatives.
633 config X86_INTEL_QUARK
634 bool "Intel Quark platform support"
636 depends on X86_EXTENDED_PLATFORM
637 depends on X86_PLATFORM_DEVICES
641 depends on X86_IO_APIC
646 Select to include support for Quark X1000 SoC.
647 Say Y here if you have a Quark based system such as the Arduino
648 compatible Intel Galileo.
650 config X86_INTEL_LPSS
651 bool "Intel Low Power Subsystem Support"
652 depends on X86 && ACPI && PCI
657 Select to build support for Intel Low Power Subsystem such as
658 found on Intel Lynxpoint PCH. Selecting this option enables
659 things like clock tree (common clock framework) and pincontrol
660 which are needed by the LPSS peripheral drivers.
662 config X86_AMD_PLATFORM_DEVICE
663 bool "AMD ACPI2Platform devices support"
668 Select to interpret AMD specific ACPI device to platform device
669 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
670 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
671 implemented under PINCTRL subsystem.
674 tristate "Intel SoC IOSF Sideband support for SoC platforms"
677 This option enables sideband register access support for Intel SoC
678 platforms. On these platforms the IOSF sideband is used in lieu of
679 MSR's for some register accesses, mostly but not limited to thermal
680 and power. Drivers may query the availability of this device to
681 determine if they need the sideband in order to work on these
682 platforms. The sideband is available on the following SoC products.
683 This list is not meant to be exclusive.
688 You should say Y if you are running a kernel on one of these SoC's.
690 config IOSF_MBI_DEBUG
691 bool "Enable IOSF sideband access through debugfs"
692 depends on IOSF_MBI && DEBUG_FS
694 Select this option to expose the IOSF sideband access registers (MCR,
695 MDR, MCRX) through debugfs to write and read register information from
696 different units on the SoC. This is most useful for obtaining device
697 state information for debug and analysis. As this is a general access
698 mechanism, users of this option would have specific knowledge of the
699 device they want to access.
701 If you don't require the option or are in doubt, say N.
704 bool "RDC R-321x SoC"
706 depends on X86_EXTENDED_PLATFORM
708 select X86_REBOOTFIXUPS
710 This option is needed for RDC R-321x system-on-chip, also known
712 If you don't have one of these chips, you should say N here.
714 config X86_32_NON_STANDARD
715 bool "Support non-standard 32-bit SMP architectures"
716 depends on X86_32 && SMP
717 depends on X86_EXTENDED_PLATFORM
719 This option compiles in the bigsmp and STA2X11 default
720 subarchitectures. It is intended for a generic binary
721 kernel. If you select them all, kernel will probe it one by
722 one and will fallback to default.
724 # Alphabetically sorted list of Non standard 32 bit platforms
726 config X86_SUPPORTS_MEMORY_FAILURE
728 # MCE code calls memory_failure():
730 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
731 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
732 depends on X86_64 || !SPARSEMEM
733 select ARCH_SUPPORTS_MEMORY_FAILURE
736 bool "STA2X11 Companion Chip Support"
737 depends on X86_32_NON_STANDARD && PCI
742 This adds support for boards based on the STA2X11 IO-Hub,
743 a.k.a. "ConneXt". The chip is used in place of the standard
744 PC chipset, so all "standard" peripherals are missing. If this
745 option is selected the kernel will still be able to boot on
746 standard PC machines.
749 tristate "Eurobraille/Iris poweroff module"
752 The Iris machines from EuroBraille do not have APM or ACPI support
753 to shut themselves down properly. A special I/O sequence is
754 needed to do so, which is what this module does at
757 This is only for Iris machines from EuroBraille.
761 config SCHED_OMIT_FRAME_POINTER
763 prompt "Single-depth WCHAN output"
766 Calculate simpler /proc/<PID>/wchan values. If this option
767 is disabled then wchan values will recurse back to the
768 caller function. This provides more accurate wchan values,
769 at the expense of slightly more scheduling overhead.
771 If in doubt, say "Y".
773 menuconfig HYPERVISOR_GUEST
774 bool "Linux guest support"
776 Say Y here to enable options for running Linux under various hyper-
777 visors. This option enables basic hypervisor detection and platform
780 If you say N, all options in this submenu will be skipped and
781 disabled, and Linux guest support won't be built in.
786 bool "Enable paravirtualization code"
787 depends on HAVE_STATIC_CALL
789 This changes the kernel so it can modify itself when it is run
790 under a hypervisor, potentially improving performance significantly
791 over full virtualization. However, when run without a hypervisor
792 the kernel is theoretically slower and slightly larger.
797 config PARAVIRT_DEBUG
798 bool "paravirt-ops debugging"
799 depends on PARAVIRT && DEBUG_KERNEL
801 Enable to debug paravirt_ops internals. Specifically, BUG if
802 a paravirt_op is missing when it is called.
804 config PARAVIRT_SPINLOCKS
805 bool "Paravirtualization layer for spinlocks"
806 depends on PARAVIRT && SMP
808 Paravirtualized spinlocks allow a pvops backend to replace the
809 spinlock implementation with something virtualization-friendly
810 (for example, block the virtual CPU rather than spinning).
812 It has a minimal impact on native kernels and gives a nice performance
813 benefit on paravirtualized KVM / Xen kernels.
815 If you are unsure how to answer this question, answer Y.
817 config X86_HV_CALLBACK_VECTOR
820 source "arch/x86/xen/Kconfig"
823 bool "KVM Guest support (including kvmclock)"
825 select PARAVIRT_CLOCK
826 select ARCH_CPUIDLE_HALTPOLL
827 select X86_HV_CALLBACK_VECTOR
830 This option enables various optimizations for running under the KVM
831 hypervisor. It includes a paravirtualized clock, so that instead
832 of relying on a PIT (or probably other) emulation by the
833 underlying device model, the host provides the guest with
834 timing infrastructure such as time of day, and system time
836 config ARCH_CPUIDLE_HALTPOLL
838 prompt "Disable host haltpoll when loading haltpoll driver"
840 If virtualized under KVM, disable host haltpoll.
843 bool "Support for running PVH guests"
845 This option enables the PVH entry point for guest virtual machines
846 as specified in the x86/HVM direct boot ABI.
848 config PARAVIRT_TIME_ACCOUNTING
849 bool "Paravirtual steal time accounting"
852 Select this option to enable fine granularity task steal time
853 accounting. Time spent executing other tasks in parallel with
854 the current vCPU is discounted from the vCPU power. To account for
855 that, there can be a small performance impact.
857 If in doubt, say N here.
859 config PARAVIRT_CLOCK
862 config JAILHOUSE_GUEST
863 bool "Jailhouse non-root cell support"
864 depends on X86_64 && PCI
867 This option allows to run Linux as guest in a Jailhouse non-root
868 cell. You can leave this option disabled if you only want to start
869 Jailhouse and run Linux afterwards in the root cell.
872 bool "ACRN Guest support"
874 select X86_HV_CALLBACK_VECTOR
876 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
877 a flexible, lightweight reference open-source hypervisor, built with
878 real-time and safety-criticality in mind. It is built for embedded
879 IOT with small footprint and real-time features. More details can be
880 found in https://projectacrn.org/.
882 config INTEL_TDX_GUEST
883 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
884 depends on X86_64 && CPU_SUP_INTEL
885 depends on X86_X2APIC
886 select ARCH_HAS_CC_PLATFORM
887 select X86_MEM_ENCRYPT
890 Support running as a guest under Intel TDX. Without this support,
891 the guest kernel can not boot or run under TDX.
892 TDX includes memory encryption and integrity capabilities
893 which protect the confidentiality and integrity of guest
894 memory contents and CPU state. TDX guests are protected from
895 some attacks from the VMM.
897 endif # HYPERVISOR_GUEST
899 source "arch/x86/Kconfig.cpu"
903 prompt "HPET Timer Support" if X86_32
905 Use the IA-PC HPET (High Precision Event Timer) to manage
906 time in preference to the PIT and RTC, if a HPET is
908 HPET is the next generation timer replacing legacy 8254s.
909 The HPET provides a stable time base on SMP
910 systems, unlike the TSC, but it is more expensive to access,
911 as it is off-chip. The interface used is documented
912 in the HPET spec, revision 1.
914 You can safely choose Y here. However, HPET will only be
915 activated if the platform and the BIOS support this feature.
916 Otherwise the 8254 will be used for timing services.
918 Choose N to continue using the legacy 8254 timer.
920 config HPET_EMULATE_RTC
922 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
924 # Mark as expert because too many people got it wrong.
925 # The code disables itself when not needed.
928 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
929 bool "Enable DMI scanning" if EXPERT
931 Enabled scanning of DMI to identify machine quirks. Say Y
932 here unless you have verified that your setup is not
933 affected by entries in the DMI blacklist. Required by PNP
937 bool "Old AMD GART IOMMU support"
941 depends on X86_64 && PCI && AMD_NB
943 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
944 GART based hardware IOMMUs.
946 The GART supports full DMA access for devices with 32-bit access
947 limitations, on systems with more than 3 GB. This is usually needed
948 for USB, sound, many IDE/SATA chipsets and some other devices.
950 Newer systems typically have a modern AMD IOMMU, supported via
951 the CONFIG_AMD_IOMMU=y config option.
953 In normal configurations this driver is only active when needed:
954 there's more than 3 GB of memory and the system contains a
955 32-bit limited device.
959 config BOOT_VESA_SUPPORT
962 If true, at least one selected framebuffer driver can take advantage
963 of VESA video modes set at an early boot stage via the vga= parameter.
966 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
967 depends on X86_64 && SMP && DEBUG_KERNEL
968 select CPUMASK_OFFSTACK
970 Enable maximum number of CPUS and NUMA Nodes for this architecture.
974 # The maximum number of CPUs supported:
976 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
977 # and which can be configured interactively in the
978 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
980 # The ranges are different on 32-bit and 64-bit kernels, depending on
981 # hardware capabilities and scalability features of the kernel.
983 # ( If MAXSMP is enabled we just use the highest possible value and disable
984 # interactive configuration. )
987 config NR_CPUS_RANGE_BEGIN
989 default NR_CPUS_RANGE_END if MAXSMP
993 config NR_CPUS_RANGE_END
996 default 64 if SMP && X86_BIGSMP
997 default 8 if SMP && !X86_BIGSMP
1000 config NR_CPUS_RANGE_END
1003 default 8192 if SMP && CPUMASK_OFFSTACK
1004 default 512 if SMP && !CPUMASK_OFFSTACK
1007 config NR_CPUS_DEFAULT
1010 default 32 if X86_BIGSMP
1014 config NR_CPUS_DEFAULT
1017 default 8192 if MAXSMP
1022 int "Maximum number of CPUs" if SMP && !MAXSMP
1023 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1024 default NR_CPUS_DEFAULT
1026 This allows you to specify the maximum number of CPUs which this
1027 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1028 supported value is 8192, otherwise the maximum value is 512. The
1029 minimum value which makes sense is 2.
1031 This is purely to save memory: each supported CPU adds about 8KB
1032 to the kernel image.
1034 config SCHED_CLUSTER
1035 bool "Cluster scheduler support"
1039 Cluster scheduler support improves the CPU scheduler's decision
1040 making when dealing with machines that have clusters of CPUs.
1041 Cluster usually means a couple of CPUs which are placed closely
1042 by sharing mid-level caches, last-level cache tags or internal
1050 prompt "Multi-core scheduler support"
1053 Multi-core scheduler support improves the CPU scheduler's decision
1054 making when dealing with multi-core CPU chips at a cost of slightly
1055 increased overhead in some places. If unsure say N here.
1057 config SCHED_MC_PRIO
1058 bool "CPU core priorities scheduler support"
1059 depends on SCHED_MC && CPU_SUP_INTEL
1060 select X86_INTEL_PSTATE
1064 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1065 core ordering determined at manufacturing time, which allows
1066 certain cores to reach higher turbo frequencies (when running
1067 single threaded workloads) than others.
1069 Enabling this kernel feature teaches the scheduler about
1070 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1071 scheduler's CPU selection logic accordingly, so that higher
1072 overall system performance can be achieved.
1074 This feature will have no effect on CPUs without this feature.
1076 If unsure say Y here.
1080 depends on !SMP && X86_LOCAL_APIC
1083 bool "Local APIC support on uniprocessors" if !PCI_MSI
1085 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1087 A local APIC (Advanced Programmable Interrupt Controller) is an
1088 integrated interrupt controller in the CPU. If you have a single-CPU
1089 system which has a processor with a local APIC, you can say Y here to
1090 enable and use it. If you say Y here even though your machine doesn't
1091 have a local APIC, then the kernel will still run with no slowdown at
1092 all. The local APIC supports CPU-generated self-interrupts (timer,
1093 performance counters), and the NMI watchdog which detects hard
1096 config X86_UP_IOAPIC
1097 bool "IO-APIC support on uniprocessors"
1098 depends on X86_UP_APIC
1100 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1101 SMP-capable replacement for PC-style interrupt controllers. Most
1102 SMP systems and many recent uniprocessor systems have one.
1104 If you have a single-CPU system with an IO-APIC, you can say Y here
1105 to use it. If you say Y here even though your machine doesn't have
1106 an IO-APIC, then the kernel will still run with no slowdown at all.
1108 config X86_LOCAL_APIC
1110 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1111 select IRQ_DOMAIN_HIERARCHY
1115 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1117 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1118 bool "Reroute for broken boot IRQs"
1119 depends on X86_IO_APIC
1121 This option enables a workaround that fixes a source of
1122 spurious interrupts. This is recommended when threaded
1123 interrupt handling is used on systems where the generation of
1124 superfluous "boot interrupts" cannot be disabled.
1126 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1127 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1128 kernel does during interrupt handling). On chipsets where this
1129 boot IRQ generation cannot be disabled, this workaround keeps
1130 the original IRQ line masked so that only the equivalent "boot
1131 IRQ" is delivered to the CPUs. The workaround also tells the
1132 kernel to set up the IRQ handler on the boot IRQ line. In this
1133 way only one interrupt is delivered to the kernel. Otherwise
1134 the spurious second interrupt may cause the kernel to bring
1135 down (vital) interrupt lines.
1137 Only affects "broken" chipsets. Interrupt sharing may be
1138 increased on these systems.
1141 bool "Machine Check / overheating reporting"
1142 select GENERIC_ALLOCATOR
1145 Machine Check support allows the processor to notify the
1146 kernel if it detects a problem (e.g. overheating, data corruption).
1147 The action the kernel takes depends on the severity of the problem,
1148 ranging from warning messages to halting the machine.
1150 config X86_MCELOG_LEGACY
1151 bool "Support for deprecated /dev/mcelog character device"
1154 Enable support for /dev/mcelog which is needed by the old mcelog
1155 userspace logging daemon. Consider switching to the new generation
1158 config X86_MCE_INTEL
1160 prompt "Intel MCE features"
1161 depends on X86_MCE && X86_LOCAL_APIC
1163 Additional support for intel specific MCE features such as
1164 the thermal monitor.
1168 prompt "AMD MCE features"
1169 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1171 Additional support for AMD specific MCE features such as
1172 the DRAM Error Threshold.
1174 config X86_ANCIENT_MCE
1175 bool "Support for old Pentium 5 / WinChip machine checks"
1176 depends on X86_32 && X86_MCE
1178 Include support for machine check handling on old Pentium 5 or WinChip
1179 systems. These typically need to be enabled explicitly on the command
1182 config X86_MCE_THRESHOLD
1183 depends on X86_MCE_AMD || X86_MCE_INTEL
1186 config X86_MCE_INJECT
1187 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1188 tristate "Machine check injector support"
1190 Provide support for injecting machine checks for testing purposes.
1191 If you don't know what a machine check is and you don't do kernel
1192 QA it is safe to say n.
1194 source "arch/x86/events/Kconfig"
1196 config X86_LEGACY_VM86
1197 bool "Legacy VM86 support"
1200 This option allows user programs to put the CPU into V8086
1201 mode, which is an 80286-era approximation of 16-bit real mode.
1203 Some very old versions of X and/or vbetool require this option
1204 for user mode setting. Similarly, DOSEMU will use it if
1205 available to accelerate real mode DOS programs. However, any
1206 recent version of DOSEMU, X, or vbetool should be fully
1207 functional even without kernel VM86 support, as they will all
1208 fall back to software emulation. Nevertheless, if you are using
1209 a 16-bit DOS program where 16-bit performance matters, vm86
1210 mode might be faster than emulation and you might want to
1213 Note that any app that works on a 64-bit kernel is unlikely to
1214 need this option, as 64-bit kernels don't, and can't, support
1215 V8086 mode. This option is also unrelated to 16-bit protected
1216 mode and is not needed to run most 16-bit programs under Wine.
1218 Enabling this option increases the complexity of the kernel
1219 and slows down exception handling a tiny bit.
1221 If unsure, say N here.
1225 default X86_LEGACY_VM86
1228 bool "Enable support for 16-bit segments" if EXPERT
1230 depends on MODIFY_LDT_SYSCALL
1232 This option is required by programs like Wine to run 16-bit
1233 protected mode legacy code on x86 processors. Disabling
1234 this option saves about 300 bytes on i386, or around 6K text
1235 plus 16K runtime memory on x86-64,
1239 depends on X86_16BIT && X86_32
1243 depends on X86_16BIT && X86_64
1245 config X86_VSYSCALL_EMULATION
1246 bool "Enable vsyscall emulation" if EXPERT
1250 This enables emulation of the legacy vsyscall page. Disabling
1251 it is roughly equivalent to booting with vsyscall=none, except
1252 that it will also disable the helpful warning if a program
1253 tries to use a vsyscall. With this option set to N, offending
1254 programs will just segfault, citing addresses of the form
1257 This option is required by many programs built before 2013, and
1258 care should be used even with newer programs if set to N.
1260 Disabling this option saves about 7K of kernel size and
1261 possibly 4K of additional runtime pagetable memory.
1263 config X86_IOPL_IOPERM
1264 bool "IOPERM and IOPL Emulation"
1267 This enables the ioperm() and iopl() syscalls which are necessary
1268 for legacy applications.
1270 Legacy IOPL support is an overbroad mechanism which allows user
1271 space aside of accessing all 65536 I/O ports also to disable
1272 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1273 capabilities and permission from potentially active security
1276 The emulation restricts the functionality of the syscall to
1277 only allowing the full range I/O port access, but prevents the
1278 ability to disable interrupts from user space which would be
1279 granted if the hardware IOPL mechanism would be used.
1282 tristate "Toshiba Laptop support"
1285 This adds a driver to safely access the System Management Mode of
1286 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1287 not work on models with a Phoenix BIOS. The System Management Mode
1288 is used to set the BIOS and power saving options on Toshiba portables.
1290 For information on utilities to make use of this driver see the
1291 Toshiba Linux utilities web site at:
1292 <http://www.buzzard.org.uk/toshiba/>.
1294 Say Y if you intend to run this kernel on a Toshiba portable.
1297 config X86_REBOOTFIXUPS
1298 bool "Enable X86 board specific fixups for reboot"
1301 This enables chipset and/or board specific fixups to be done
1302 in order to get reboot to work correctly. This is only needed on
1303 some combinations of hardware and BIOS. The symptom, for which
1304 this config is intended, is when reboot ends with a stalled/hung
1307 Currently, the only fixup is for the Geode machines using
1308 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1310 Say Y if you want to enable the fixup. Currently, it's safe to
1311 enable this option even if you don't need it.
1315 bool "CPU microcode loading support"
1317 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1319 If you say Y here, you will be able to update the microcode on
1320 Intel and AMD processors. The Intel support is for the IA32 family,
1321 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1322 AMD support is for families 0x10 and later. You will obviously need
1323 the actual microcode binary data itself which is not shipped with
1326 The preferred method to load microcode from a detached initrd is described
1327 in Documentation/arch/x86/microcode.rst. For that you need to enable
1328 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1329 initrd for microcode blobs.
1331 In addition, you can build the microcode into the kernel. For that you
1332 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1335 config MICROCODE_INTEL
1336 bool "Intel microcode loading support"
1337 depends on CPU_SUP_INTEL && MICROCODE
1340 This options enables microcode patch loading support for Intel
1343 For the current Intel microcode data package go to
1344 <https://downloadcenter.intel.com> and search for
1345 'Linux Processor Microcode Data File'.
1347 config MICROCODE_AMD
1348 bool "AMD microcode loading support"
1349 depends on CPU_SUP_AMD && MICROCODE
1351 If you select this option, microcode patch loading support for AMD
1352 processors will be enabled.
1354 config MICROCODE_LATE_LOADING
1355 bool "Late microcode loading (DANGEROUS)"
1357 depends on MICROCODE
1359 Loading microcode late, when the system is up and executing instructions
1360 is a tricky business and should be avoided if possible. Just the sequence
1361 of synchronizing all cores and SMT threads is one fragile dance which does
1362 not guarantee that cores might not softlock after the loading. Therefore,
1363 use this at your own risk. Late loading taints the kernel too.
1366 tristate "/dev/cpu/*/msr - Model-specific register support"
1368 This device gives privileged processes access to the x86
1369 Model-Specific Registers (MSRs). It is a character device with
1370 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1371 MSR accesses are directed to a specific CPU on multi-processor
1375 tristate "/dev/cpu/*/cpuid - CPU information support"
1377 This device gives processes access to the x86 CPUID instruction to
1378 be executed on a specific processor. It is a character device
1379 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1383 prompt "High Memory Support"
1390 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1391 However, the address space of 32-bit x86 processors is only 4
1392 Gigabytes large. That means that, if you have a large amount of
1393 physical memory, not all of it can be "permanently mapped" by the
1394 kernel. The physical memory that's not permanently mapped is called
1397 If you are compiling a kernel which will never run on a machine with
1398 more than 1 Gigabyte total physical RAM, answer "off" here (default
1399 choice and suitable for most users). This will result in a "3GB/1GB"
1400 split: 3GB are mapped so that each process sees a 3GB virtual memory
1401 space and the remaining part of the 4GB virtual memory space is used
1402 by the kernel to permanently map as much physical memory as
1405 If the machine has between 1 and 4 Gigabytes physical RAM, then
1408 If more than 4 Gigabytes is used then answer "64GB" here. This
1409 selection turns Intel PAE (Physical Address Extension) mode on.
1410 PAE implements 3-level paging on IA32 processors. PAE is fully
1411 supported by Linux, PAE mode is implemented on all recent Intel
1412 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1413 then the kernel will not boot on CPUs that don't support PAE!
1415 The actual amount of total physical memory will either be
1416 auto detected or can be forced by using a kernel command line option
1417 such as "mem=256M". (Try "man bootparam" or see the documentation of
1418 your boot loader (lilo or loadlin) about how to pass options to the
1419 kernel at boot time.)
1421 If unsure, say "off".
1426 Select this if you have a 32-bit processor and between 1 and 4
1427 gigabytes of physical RAM.
1431 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1434 Select this if you have a 32-bit processor and more than 4
1435 gigabytes of physical RAM.
1440 prompt "Memory split" if EXPERT
1444 Select the desired split between kernel and user memory.
1446 If the address range available to the kernel is less than the
1447 physical memory installed, the remaining memory will be available
1448 as "high memory". Accessing high memory is a little more costly
1449 than low memory, as it needs to be mapped into the kernel first.
1450 Note that increasing the kernel address space limits the range
1451 available to user programs, making the address space there
1452 tighter. Selecting anything other than the default 3G/1G split
1453 will also likely make your kernel incompatible with binary-only
1456 If you are not absolutely sure what you are doing, leave this
1460 bool "3G/1G user/kernel split"
1461 config VMSPLIT_3G_OPT
1463 bool "3G/1G user/kernel split (for full 1G low memory)"
1465 bool "2G/2G user/kernel split"
1466 config VMSPLIT_2G_OPT
1468 bool "2G/2G user/kernel split (for full 2G low memory)"
1470 bool "1G/3G user/kernel split"
1475 default 0xB0000000 if VMSPLIT_3G_OPT
1476 default 0x80000000 if VMSPLIT_2G
1477 default 0x78000000 if VMSPLIT_2G_OPT
1478 default 0x40000000 if VMSPLIT_1G
1484 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1487 bool "PAE (Physical Address Extension) Support"
1488 depends on X86_32 && !HIGHMEM4G
1489 select PHYS_ADDR_T_64BIT
1492 PAE is required for NX support, and furthermore enables
1493 larger swapspace support for non-overcommit purposes. It
1494 has the cost of more pagetable lookup overhead, and also
1495 consumes more pagetable space per process.
1498 bool "Enable 5-level page tables support"
1500 select DYNAMIC_MEMORY_LAYOUT
1501 select SPARSEMEM_VMEMMAP
1504 5-level paging enables access to larger address space:
1505 up to 128 PiB of virtual address space and 4 PiB of
1506 physical address space.
1508 It will be supported by future Intel CPUs.
1510 A kernel with the option enabled can be booted on machines that
1511 support 4- or 5-level paging.
1513 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1518 config X86_DIRECT_GBPAGES
1522 Certain kernel features effectively disable kernel
1523 linear 1 GB mappings (even if the CPU otherwise
1524 supports them), so don't confuse the user by printing
1525 that we have them enabled.
1527 config X86_CPA_STATISTICS
1528 bool "Enable statistic for Change Page Attribute"
1531 Expose statistics about the Change Page Attribute mechanism, which
1532 helps to determine the effectiveness of preserving large and huge
1533 page mappings when mapping protections are changed.
1535 config X86_MEM_ENCRYPT
1536 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1537 select DYNAMIC_PHYSICAL_MASK
1540 config AMD_MEM_ENCRYPT
1541 bool "AMD Secure Memory Encryption (SME) support"
1542 depends on X86_64 && CPU_SUP_AMD
1543 select DMA_COHERENT_POOL
1544 select ARCH_USE_MEMREMAP_PROT
1545 select INSTRUCTION_DECODER
1546 select ARCH_HAS_CC_PLATFORM
1547 select X86_MEM_ENCRYPT
1549 Say yes to enable support for the encryption of system memory.
1550 This requires an AMD processor that supports Secure Memory
1553 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1554 bool "Activate AMD Secure Memory Encryption (SME) by default"
1555 depends on AMD_MEM_ENCRYPT
1557 Say yes to have system memory encrypted by default if running on
1558 an AMD processor that supports Secure Memory Encryption (SME).
1560 If set to Y, then the encryption of system memory can be
1561 deactivated with the mem_encrypt=off command line option.
1563 If set to N, then the encryption of system memory can be
1564 activated with the mem_encrypt=on command line option.
1566 # Common NUMA Features
1568 bool "NUMA Memory Allocation and Scheduler Support"
1570 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1571 default y if X86_BIGSMP
1572 select USE_PERCPU_NUMA_NODE_ID
1574 Enable NUMA (Non-Uniform Memory Access) support.
1576 The kernel will try to allocate memory used by a CPU on the
1577 local memory controller of the CPU and add some more
1578 NUMA awareness to the kernel.
1580 For 64-bit this is recommended if the system is Intel Core i7
1581 (or later), AMD Opteron, or EM64T NUMA.
1583 For 32-bit this is only needed if you boot a 32-bit
1584 kernel on a 64-bit NUMA platform.
1586 Otherwise, you should say N.
1590 prompt "Old style AMD Opteron NUMA detection"
1591 depends on X86_64 && NUMA && PCI
1593 Enable AMD NUMA node topology detection. You should say Y here if
1594 you have a multi processor AMD system. This uses an old method to
1595 read the NUMA configuration directly from the builtin Northbridge
1596 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1597 which also takes priority if both are compiled in.
1599 config X86_64_ACPI_NUMA
1601 prompt "ACPI NUMA detection"
1602 depends on X86_64 && NUMA && ACPI && PCI
1605 Enable ACPI SRAT based node topology detection.
1608 bool "NUMA emulation"
1611 Enable NUMA emulation. A flat machine will be split
1612 into virtual nodes when booted with "numa=fake=N", where N is the
1613 number of nodes. This is only useful for debugging.
1616 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1618 default "10" if MAXSMP
1619 default "6" if X86_64
1623 Specify the maximum number of NUMA Nodes available on the target
1624 system. Increases memory reserved to accommodate various tables.
1626 config ARCH_FLATMEM_ENABLE
1628 depends on X86_32 && !NUMA
1630 config ARCH_SPARSEMEM_ENABLE
1632 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1633 select SPARSEMEM_STATIC if X86_32
1634 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1636 config ARCH_SPARSEMEM_DEFAULT
1637 def_bool X86_64 || (NUMA && X86_32)
1639 config ARCH_SELECT_MEMORY_MODEL
1641 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1643 config ARCH_MEMORY_PROBE
1644 bool "Enable sysfs memory/probe interface"
1645 depends on MEMORY_HOTPLUG
1647 This option enables a sysfs memory/probe interface for testing.
1648 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1649 If you are unsure how to answer this question, answer N.
1651 config ARCH_PROC_KCORE_TEXT
1653 depends on X86_64 && PROC_KCORE
1655 config ILLEGAL_POINTER_VALUE
1658 default 0xdead000000000000 if X86_64
1660 config X86_PMEM_LEGACY_DEVICE
1663 config X86_PMEM_LEGACY
1664 tristate "Support non-standard NVDIMMs and ADR protected memory"
1665 depends on PHYS_ADDR_T_64BIT
1667 select X86_PMEM_LEGACY_DEVICE
1668 select NUMA_KEEP_MEMINFO if NUMA
1671 Treat memory marked using the non-standard e820 type of 12 as used
1672 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1673 The kernel will offer these regions to the 'pmem' driver so
1674 they can be used for persistent storage.
1679 bool "Allocate 3rd-level pagetables from highmem"
1682 The VM uses one page table entry for each page of physical memory.
1683 For systems with a lot of RAM, this can be wasteful of precious
1684 low memory. Setting this option will put user-space page table
1685 entries in high memory.
1687 config X86_CHECK_BIOS_CORRUPTION
1688 bool "Check for low memory corruption"
1690 Periodically check for memory corruption in low memory, which
1691 is suspected to be caused by BIOS. Even when enabled in the
1692 configuration, it is disabled at runtime. Enable it by
1693 setting "memory_corruption_check=1" on the kernel command
1694 line. By default it scans the low 64k of memory every 60
1695 seconds; see the memory_corruption_check_size and
1696 memory_corruption_check_period parameters in
1697 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1699 When enabled with the default parameters, this option has
1700 almost no overhead, as it reserves a relatively small amount
1701 of memory and scans it infrequently. It both detects corruption
1702 and prevents it from affecting the running system.
1704 It is, however, intended as a diagnostic tool; if repeatable
1705 BIOS-originated corruption always affects the same memory,
1706 you can use memmap= to prevent the kernel from using that
1709 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1710 bool "Set the default setting of memory_corruption_check"
1711 depends on X86_CHECK_BIOS_CORRUPTION
1714 Set whether the default state of memory_corruption_check is
1717 config MATH_EMULATION
1719 depends on MODIFY_LDT_SYSCALL
1720 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1722 Linux can emulate a math coprocessor (used for floating point
1723 operations) if you don't have one. 486DX and Pentium processors have
1724 a math coprocessor built in, 486SX and 386 do not, unless you added
1725 a 487DX or 387, respectively. (The messages during boot time can
1726 give you some hints here ["man dmesg"].) Everyone needs either a
1727 coprocessor or this emulation.
1729 If you don't have a math coprocessor, you need to say Y here; if you
1730 say Y here even though you have a coprocessor, the coprocessor will
1731 be used nevertheless. (This behavior can be changed with the kernel
1732 command line option "no387", which comes handy if your coprocessor
1733 is broken. Try "man bootparam" or see the documentation of your boot
1734 loader (lilo or loadlin) about how to pass options to the kernel at
1735 boot time.) This means that it is a good idea to say Y here if you
1736 intend to use this kernel on different machines.
1738 More information about the internals of the Linux math coprocessor
1739 emulation can be found in <file:arch/x86/math-emu/README>.
1741 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1742 kernel, it won't hurt.
1746 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1748 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1749 the Memory Type Range Registers (MTRRs) may be used to control
1750 processor access to memory ranges. This is most useful if you have
1751 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1752 allows bus write transfers to be combined into a larger transfer
1753 before bursting over the PCI/AGP bus. This can increase performance
1754 of image write operations 2.5 times or more. Saying Y here creates a
1755 /proc/mtrr file which may be used to manipulate your processor's
1756 MTRRs. Typically the X server should use this.
1758 This code has a reasonably generic interface so that similar
1759 control registers on other processors can be easily supported
1762 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1763 Registers (ARRs) which provide a similar functionality to MTRRs. For
1764 these, the ARRs are used to emulate the MTRRs.
1765 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1766 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1767 write-combining. All of these processors are supported by this code
1768 and it makes sense to say Y here if you have one of them.
1770 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1771 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1772 can lead to all sorts of problems, so it's good to say Y here.
1774 You can safely say Y even if your machine doesn't have MTRRs, you'll
1775 just add about 9 KB to your kernel.
1777 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1779 config MTRR_SANITIZER
1781 prompt "MTRR cleanup support"
1784 Convert MTRR layout from continuous to discrete, so X drivers can
1785 add writeback entries.
1787 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1788 The largest mtrr entry size for a continuous block can be set with
1793 config MTRR_SANITIZER_ENABLE_DEFAULT
1794 int "MTRR cleanup enable value (0-1)"
1797 depends on MTRR_SANITIZER
1799 Enable mtrr cleanup default value
1801 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1802 int "MTRR cleanup spare reg num (0-7)"
1805 depends on MTRR_SANITIZER
1807 mtrr cleanup spare entries default, it can be changed via
1808 mtrr_spare_reg_nr=N on the kernel command line.
1812 prompt "x86 PAT support" if EXPERT
1815 Use PAT attributes to setup page level cache control.
1817 PATs are the modern equivalents of MTRRs and are much more
1818 flexible than MTRRs.
1820 Say N here if you see bootup problems (boot crash, boot hang,
1821 spontaneous reboots) or a non-working video driver.
1825 config ARCH_USES_PG_UNCACHED
1831 prompt "User Mode Instruction Prevention" if EXPERT
1833 User Mode Instruction Prevention (UMIP) is a security feature in
1834 some x86 processors. If enabled, a general protection fault is
1835 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1836 executed in user mode. These instructions unnecessarily expose
1837 information about the hardware state.
1839 The vast majority of applications do not use these instructions.
1840 For the very few that do, software emulation is provided in
1841 specific cases in protected and virtual-8086 modes. Emulated
1845 # GCC >= 9 and binutils >= 2.29
1846 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1848 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1849 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1850 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1851 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1854 config X86_KERNEL_IBT
1855 prompt "Indirect Branch Tracking"
1857 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1858 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1859 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1862 Build the kernel with support for Indirect Branch Tracking, a
1863 hardware support course-grain forward-edge Control Flow Integrity
1864 protection. It enforces that all indirect calls must land on
1865 an ENDBR instruction, as such, the compiler will instrument the
1866 code with them to make this happen.
1868 In addition to building the kernel with IBT, seal all functions that
1869 are not indirect call targets, avoiding them ever becoming one.
1871 This requires LTO like objtool runs and will slow down the build. It
1872 does significantly reduce the number of ENDBR instructions in the
1875 config X86_INTEL_MEMORY_PROTECTION_KEYS
1876 prompt "Memory Protection Keys"
1878 # Note: only available in 64-bit mode
1879 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1880 select ARCH_USES_HIGH_VMA_FLAGS
1881 select ARCH_HAS_PKEYS
1883 Memory Protection Keys provides a mechanism for enforcing
1884 page-based protections, but without requiring modification of the
1885 page tables when an application changes protection domains.
1887 For details, see Documentation/core-api/protection-keys.rst
1892 prompt "TSX enable mode"
1893 depends on CPU_SUP_INTEL
1894 default X86_INTEL_TSX_MODE_OFF
1896 Intel's TSX (Transactional Synchronization Extensions) feature
1897 allows to optimize locking protocols through lock elision which
1898 can lead to a noticeable performance boost.
1900 On the other hand it has been shown that TSX can be exploited
1901 to form side channel attacks (e.g. TAA) and chances are there
1902 will be more of those attacks discovered in the future.
1904 Therefore TSX is not enabled by default (aka tsx=off). An admin
1905 might override this decision by tsx=on the command line parameter.
1906 Even with TSX enabled, the kernel will attempt to enable the best
1907 possible TAA mitigation setting depending on the microcode available
1908 for the particular machine.
1910 This option allows to set the default tsx mode between tsx=on, =off
1911 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1914 Say off if not sure, auto if TSX is in use but it should be used on safe
1915 platforms or on if TSX is in use and the security aspect of tsx is not
1918 config X86_INTEL_TSX_MODE_OFF
1921 TSX is disabled if possible - equals to tsx=off command line parameter.
1923 config X86_INTEL_TSX_MODE_ON
1926 TSX is always enabled on TSX capable HW - equals the tsx=on command
1929 config X86_INTEL_TSX_MODE_AUTO
1932 TSX is enabled on TSX capable HW that is believed to be safe against
1933 side channel attacks- equals the tsx=auto command line parameter.
1937 bool "Software Guard eXtensions (SGX)"
1938 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1940 depends on CRYPTO_SHA256=y
1942 select NUMA_KEEP_MEMINFO if NUMA
1945 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1946 that can be used by applications to set aside private regions of code
1947 and data, referred to as enclaves. An enclave's private memory can
1948 only be accessed by code running within the enclave. Accesses from
1949 outside the enclave, including other enclaves, are disallowed by
1955 bool "EFI runtime service support"
1958 select EFI_RUNTIME_WRAPPERS
1959 select ARCH_USE_MEMREMAP_PROT
1961 This enables the kernel to use EFI runtime services that are
1962 available (such as the EFI variable services).
1964 This option is only useful on systems that have EFI firmware.
1965 In addition, you should use the latest ELILO loader available
1966 at <http://elilo.sourceforge.net> in order to take advantage
1967 of EFI runtime services. However, even with this option, the
1968 resultant kernel should continue to boot on existing non-EFI
1972 bool "EFI stub support"
1976 This kernel feature allows a bzImage to be loaded directly
1977 by EFI firmware without the use of a bootloader.
1979 See Documentation/admin-guide/efi-stub.rst for more information.
1981 config EFI_HANDOVER_PROTOCOL
1982 bool "EFI handover protocol (DEPRECATED)"
1986 Select this in order to include support for the deprecated EFI
1987 handover protocol, which defines alternative entry points into the
1988 EFI stub. This is a practice that has no basis in the UEFI
1989 specification, and requires a priori knowledge on the part of the
1990 bootloader about Linux/x86 specific ways of passing the command line
1991 and initrd, and where in memory those assets may be loaded.
1993 If in doubt, say Y. Even though the corresponding support is not
1994 present in upstream GRUB or other bootloaders, most distros build
1995 GRUB with numerous downstream patches applied, and may rely on the
1996 handover protocol as as result.
1999 bool "EFI mixed-mode support"
2000 depends on EFI_STUB && X86_64
2002 Enabling this feature allows a 64-bit kernel to be booted
2003 on a 32-bit firmware, provided that your CPU supports 64-bit
2006 Note that it is not possible to boot a mixed-mode enabled
2007 kernel via the EFI boot stub - a bootloader that supports
2008 the EFI handover protocol must be used.
2012 config EFI_FAKE_MEMMAP
2013 bool "Enable EFI fake memory map"
2016 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2017 this parameter, you can add arbitrary attribute to specific memory
2018 range by updating original (firmware provided) EFI memmap. This is
2019 useful for debugging of EFI memmap related feature, e.g., Address
2020 Range Mirroring feature.
2022 config EFI_MAX_FAKE_MEM
2023 int "maximum allowable number of ranges in efi_fake_mem boot option"
2024 depends on EFI_FAKE_MEMMAP
2028 Maximum allowable number of ranges in efi_fake_mem boot option.
2029 Ranges can be set up to this value using comma-separated list.
2030 The default value is 8.
2032 config EFI_RUNTIME_MAP
2033 bool "Export EFI runtime maps to sysfs" if EXPERT
2037 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2038 That memory map is required by the 2nd kernel to set up EFI virtual
2039 mappings after kexec, but can also be used for debugging purposes.
2041 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2043 source "kernel/Kconfig.hz"
2046 bool "kexec system call"
2049 kexec is a system call that implements the ability to shutdown your
2050 current kernel, and to start another kernel. It is like a reboot
2051 but it is independent of the system firmware. And like a reboot
2052 you can start any kernel with it, not just Linux.
2054 The name comes from the similarity to the exec system call.
2056 It is an ongoing process to be certain the hardware in a machine
2057 is properly shutdown, so do not be surprised if this code does not
2058 initially work for you. As of this writing the exact hardware
2059 interface is strongly in flux, so no good recommendation can be
2063 bool "kexec file based system call"
2065 select HAVE_IMA_KEXEC if IMA
2068 depends on CRYPTO_SHA256=y
2070 This is new version of kexec system call. This system call is
2071 file based and takes file descriptors as system call argument
2072 for kernel and initramfs as opposed to list of segments as
2073 accepted by previous system call.
2075 config ARCH_HAS_KEXEC_PURGATORY
2079 bool "Verify kernel signature during kexec_file_load() syscall"
2080 depends on KEXEC_FILE
2083 This option makes the kexec_file_load() syscall check for a valid
2084 signature of the kernel image. The image can still be loaded without
2085 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2086 there's a signature that we can check, then it must be valid.
2088 In addition to this option, you need to enable signature
2089 verification for the corresponding kernel image type being
2090 loaded in order for this to work.
2092 config KEXEC_SIG_FORCE
2093 bool "Require a valid signature in kexec_file_load() syscall"
2094 depends on KEXEC_SIG
2096 This option makes kernel signature verification mandatory for
2097 the kexec_file_load() syscall.
2099 config KEXEC_BZIMAGE_VERIFY_SIG
2100 bool "Enable bzImage signature verification support"
2101 depends on KEXEC_SIG
2102 depends on SIGNED_PE_FILE_VERIFICATION
2103 select SYSTEM_TRUSTED_KEYRING
2105 Enable bzImage signature verification support.
2108 bool "kernel crash dumps"
2109 depends on X86_64 || (X86_32 && HIGHMEM)
2111 Generate crash dump after being started by kexec.
2112 This should be normally only set in special crash dump kernels
2113 which are loaded in the main kernel with kexec-tools into
2114 a specially reserved region and then later executed after
2115 a crash by kdump/kexec. The crash dump kernel must be compiled
2116 to a memory address not used by the main kernel or BIOS using
2117 PHYSICAL_START, or it must be built as a relocatable image
2118 (CONFIG_RELOCATABLE=y).
2119 For more details see Documentation/admin-guide/kdump/kdump.rst
2123 depends on KEXEC && HIBERNATION
2125 Jump between original kernel and kexeced kernel and invoke
2126 code in physical address mode via KEXEC
2128 config PHYSICAL_START
2129 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2132 This gives the physical address where the kernel is loaded.
2134 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2135 bzImage will decompress itself to above physical address and
2136 run from there. Otherwise, bzImage will run from the address where
2137 it has been loaded by the boot loader and will ignore above physical
2140 In normal kdump cases one does not have to set/change this option
2141 as now bzImage can be compiled as a completely relocatable image
2142 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2143 address. This option is mainly useful for the folks who don't want
2144 to use a bzImage for capturing the crash dump and want to use a
2145 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2146 to be specifically compiled to run from a specific memory area
2147 (normally a reserved region) and this option comes handy.
2149 So if you are using bzImage for capturing the crash dump,
2150 leave the value here unchanged to 0x1000000 and set
2151 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2152 for capturing the crash dump change this value to start of
2153 the reserved region. In other words, it can be set based on
2154 the "X" value as specified in the "crashkernel=YM@XM"
2155 command line boot parameter passed to the panic-ed
2156 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2157 for more details about crash dumps.
2159 Usage of bzImage for capturing the crash dump is recommended as
2160 one does not have to build two kernels. Same kernel can be used
2161 as production kernel and capture kernel. Above option should have
2162 gone away after relocatable bzImage support is introduced. But it
2163 is present because there are users out there who continue to use
2164 vmlinux for dump capture. This option should go away down the
2167 Don't change this unless you know what you are doing.
2170 bool "Build a relocatable kernel"
2173 This builds a kernel image that retains relocation information
2174 so it can be loaded someplace besides the default 1MB.
2175 The relocations tend to make the kernel binary about 10% larger,
2176 but are discarded at runtime.
2178 One use is for the kexec on panic case where the recovery kernel
2179 must live at a different physical address than the primary
2182 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2183 it has been loaded at and the compile time physical address
2184 (CONFIG_PHYSICAL_START) is used as the minimum location.
2186 config RANDOMIZE_BASE
2187 bool "Randomize the address of the kernel image (KASLR)"
2188 depends on RELOCATABLE
2191 In support of Kernel Address Space Layout Randomization (KASLR),
2192 this randomizes the physical address at which the kernel image
2193 is decompressed and the virtual address where the kernel
2194 image is mapped, as a security feature that deters exploit
2195 attempts relying on knowledge of the location of kernel
2198 On 64-bit, the kernel physical and virtual addresses are
2199 randomized separately. The physical address will be anywhere
2200 between 16MB and the top of physical memory (up to 64TB). The
2201 virtual address will be randomized from 16MB up to 1GB (9 bits
2202 of entropy). Note that this also reduces the memory space
2203 available to kernel modules from 1.5GB to 1GB.
2205 On 32-bit, the kernel physical and virtual addresses are
2206 randomized together. They will be randomized from 16MB up to
2207 512MB (8 bits of entropy).
2209 Entropy is generated using the RDRAND instruction if it is
2210 supported. If RDTSC is supported, its value is mixed into
2211 the entropy pool as well. If neither RDRAND nor RDTSC are
2212 supported, then entropy is read from the i8254 timer. The
2213 usable entropy is limited by the kernel being built using
2214 2GB addressing, and that PHYSICAL_ALIGN must be at a
2215 minimum of 2MB. As a result, only 10 bits of entropy are
2216 theoretically possible, but the implementations are further
2217 limited due to memory layouts.
2221 # Relocation on x86 needs some additional build support
2222 config X86_NEED_RELOCS
2224 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2226 config PHYSICAL_ALIGN
2227 hex "Alignment value to which kernel should be aligned"
2229 range 0x2000 0x1000000 if X86_32
2230 range 0x200000 0x1000000 if X86_64
2232 This value puts the alignment restrictions on physical address
2233 where kernel is loaded and run from. Kernel is compiled for an
2234 address which meets above alignment restriction.
2236 If bootloader loads the kernel at a non-aligned address and
2237 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2238 address aligned to above value and run from there.
2240 If bootloader loads the kernel at a non-aligned address and
2241 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2242 load address and decompress itself to the address it has been
2243 compiled for and run from there. The address for which kernel is
2244 compiled already meets above alignment restrictions. Hence the
2245 end result is that kernel runs from a physical address meeting
2246 above alignment restrictions.
2248 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2249 this value must be a multiple of 0x200000.
2251 Don't change this unless you know what you are doing.
2253 config DYNAMIC_MEMORY_LAYOUT
2256 This option makes base addresses of vmalloc and vmemmap as well as
2257 __PAGE_OFFSET movable during boot.
2259 config RANDOMIZE_MEMORY
2260 bool "Randomize the kernel memory sections"
2262 depends on RANDOMIZE_BASE
2263 select DYNAMIC_MEMORY_LAYOUT
2264 default RANDOMIZE_BASE
2266 Randomizes the base virtual address of kernel memory sections
2267 (physical memory mapping, vmalloc & vmemmap). This security feature
2268 makes exploits relying on predictable memory locations less reliable.
2270 The order of allocations remains unchanged. Entropy is generated in
2271 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2272 configuration have in average 30,000 different possible virtual
2273 addresses for each memory section.
2277 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2278 hex "Physical memory mapping padding" if EXPERT
2279 depends on RANDOMIZE_MEMORY
2280 default "0xa" if MEMORY_HOTPLUG
2282 range 0x1 0x40 if MEMORY_HOTPLUG
2285 Define the padding in terabytes added to the existing physical
2286 memory size during kernel memory randomization. It is useful
2287 for memory hotplug support but reduces the entropy available for
2288 address randomization.
2290 If unsure, leave at the default value.
2296 config BOOTPARAM_HOTPLUG_CPU0
2297 bool "Set default setting of cpu0_hotpluggable"
2298 depends on HOTPLUG_CPU
2300 Set whether default state of cpu0_hotpluggable is on or off.
2302 Say Y here to enable CPU0 hotplug by default. If this switch
2303 is turned on, there is no need to give cpu0_hotplug kernel
2304 parameter and the CPU0 hotplug feature is enabled by default.
2306 Please note: there are two known CPU0 dependencies if you want
2307 to enable the CPU0 hotplug feature either by this switch or by
2308 cpu0_hotplug kernel parameter.
2310 First, resume from hibernate or suspend always starts from CPU0.
2311 So hibernate and suspend are prevented if CPU0 is offline.
2313 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2314 offline if any interrupt can not migrate out of CPU0. There may
2315 be other CPU0 dependencies.
2317 Please make sure the dependencies are under your control before
2318 you enable this feature.
2320 Say N if you don't want to enable CPU0 hotplug feature by default.
2321 You still can enable the CPU0 hotplug feature at boot by kernel
2322 parameter cpu0_hotplug.
2324 config DEBUG_HOTPLUG_CPU0
2326 prompt "Debug CPU0 hotplug"
2327 depends on HOTPLUG_CPU
2329 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2330 soon as possible and boots up userspace with CPU0 offlined. User
2331 can online CPU0 back after boot time.
2333 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2334 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2335 compilation or giving cpu0_hotplug kernel parameter at boot.
2341 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2342 depends on COMPAT_32
2344 Certain buggy versions of glibc will crash if they are
2345 presented with a 32-bit vDSO that is not mapped at the address
2346 indicated in its segment table.
2348 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2349 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2350 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2351 the only released version with the bug, but OpenSUSE 9
2352 contains a buggy "glibc 2.3.2".
2354 The symptom of the bug is that everything crashes on startup, saying:
2355 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2357 Saying Y here changes the default value of the vdso32 boot
2358 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2359 This works around the glibc bug but hurts performance.
2361 If unsure, say N: if you are compiling your own kernel, you
2362 are unlikely to be using a buggy version of glibc.
2365 prompt "vsyscall table for legacy applications"
2367 default LEGACY_VSYSCALL_XONLY
2369 Legacy user code that does not know how to find the vDSO expects
2370 to be able to issue three syscalls by calling fixed addresses in
2371 kernel space. Since this location is not randomized with ASLR,
2372 it can be used to assist security vulnerability exploitation.
2374 This setting can be changed at boot time via the kernel command
2375 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2376 is deprecated and can only be enabled using the kernel command
2379 On a system with recent enough glibc (2.14 or newer) and no
2380 static binaries, you can say None without a performance penalty
2381 to improve security.
2383 If unsure, select "Emulate execution only".
2385 config LEGACY_VSYSCALL_XONLY
2386 bool "Emulate execution only"
2388 The kernel traps and emulates calls into the fixed vsyscall
2389 address mapping and does not allow reads. This
2390 configuration is recommended when userspace might use the
2391 legacy vsyscall area but support for legacy binary
2392 instrumentation of legacy code is not needed. It mitigates
2393 certain uses of the vsyscall area as an ASLR-bypassing
2396 config LEGACY_VSYSCALL_NONE
2399 There will be no vsyscall mapping at all. This will
2400 eliminate any risk of ASLR bypass due to the vsyscall
2401 fixed address mapping. Attempts to use the vsyscalls
2402 will be reported to dmesg, so that either old or
2403 malicious userspace programs can be identified.
2408 bool "Built-in kernel command line"
2410 Allow for specifying boot arguments to the kernel at
2411 build time. On some systems (e.g. embedded ones), it is
2412 necessary or convenient to provide some or all of the
2413 kernel boot arguments with the kernel itself (that is,
2414 to not rely on the boot loader to provide them.)
2416 To compile command line arguments into the kernel,
2417 set this option to 'Y', then fill in the
2418 boot arguments in CONFIG_CMDLINE.
2420 Systems with fully functional boot loaders (i.e. non-embedded)
2421 should leave this option set to 'N'.
2424 string "Built-in kernel command string"
2425 depends on CMDLINE_BOOL
2428 Enter arguments here that should be compiled into the kernel
2429 image and used at boot time. If the boot loader provides a
2430 command line at boot time, it is appended to this string to
2431 form the full kernel command line, when the system boots.
2433 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2434 change this behavior.
2436 In most cases, the command line (whether built-in or provided
2437 by the boot loader) should specify the device for the root
2440 config CMDLINE_OVERRIDE
2441 bool "Built-in command line overrides boot loader arguments"
2442 depends on CMDLINE_BOOL && CMDLINE != ""
2444 Set this option to 'Y' to have the kernel ignore the boot loader
2445 command line, and use ONLY the built-in command line.
2447 This is used to work around broken boot loaders. This should
2448 be set to 'N' under normal conditions.
2450 config MODIFY_LDT_SYSCALL
2451 bool "Enable the LDT (local descriptor table)" if EXPERT
2454 Linux can allow user programs to install a per-process x86
2455 Local Descriptor Table (LDT) using the modify_ldt(2) system
2456 call. This is required to run 16-bit or segmented code such as
2457 DOSEMU or some Wine programs. It is also used by some very old
2458 threading libraries.
2460 Enabling this feature adds a small amount of overhead to
2461 context switches and increases the low-level kernel attack
2462 surface. Disabling it removes the modify_ldt(2) system call.
2464 Saying 'N' here may make sense for embedded or server kernels.
2466 config STRICT_SIGALTSTACK_SIZE
2467 bool "Enforce strict size checking for sigaltstack"
2468 depends on DYNAMIC_SIGFRAME
2470 For historical reasons MINSIGSTKSZ is a constant which became
2471 already too small with AVX512 support. Add a mechanism to
2472 enforce strict checking of the sigaltstack size against the
2473 real size of the FPU frame. This option enables the check
2474 by default. It can also be controlled via the kernel command
2475 line option 'strict_sas_size' independent of this config
2476 switch. Enabling it might break existing applications which
2477 allocate a too small sigaltstack but 'work' because they
2478 never get a signal delivered.
2480 Say 'N' unless you want to really enforce this check.
2482 source "kernel/livepatch/Kconfig"
2487 def_bool $(cc-option,-mharden-sls=all)
2489 config CC_HAS_RETURN_THUNK
2490 def_bool $(cc-option,-mfunction-return=thunk-extern)
2492 config CC_HAS_ENTRY_PADDING
2493 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2495 config FUNCTION_PADDING_CFI
2497 default 59 if FUNCTION_ALIGNMENT_64B
2498 default 27 if FUNCTION_ALIGNMENT_32B
2499 default 11 if FUNCTION_ALIGNMENT_16B
2500 default 3 if FUNCTION_ALIGNMENT_8B
2503 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2504 # except Kconfig can't do arithmetic :/
2505 config FUNCTION_PADDING_BYTES
2507 default FUNCTION_PADDING_CFI if CFI_CLANG
2508 default FUNCTION_ALIGNMENT
2512 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2513 select FUNCTION_ALIGNMENT_16B
2517 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2520 config HAVE_CALL_THUNKS
2522 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2528 config PREFIX_SYMBOLS
2530 depends on CALL_PADDING && !CFI_CLANG
2532 menuconfig SPECULATION_MITIGATIONS
2533 bool "Mitigations for speculative execution vulnerabilities"
2536 Say Y here to enable options which enable mitigations for
2537 speculative execution hardware vulnerabilities.
2539 If you say N, all mitigations will be disabled. You really
2540 should know what you are doing to say so.
2542 if SPECULATION_MITIGATIONS
2544 config PAGE_TABLE_ISOLATION
2545 bool "Remove the kernel mapping in user mode"
2547 depends on (X86_64 || X86_PAE)
2549 This feature reduces the number of hardware side channels by
2550 ensuring that the majority of kernel addresses are not mapped
2553 See Documentation/arch/x86/pti.rst for more details.
2556 bool "Avoid speculative indirect branches in kernel"
2557 select OBJTOOL if HAVE_OBJTOOL
2560 Compile kernel with the retpoline compiler options to guard against
2561 kernel-to-user data leaks by avoiding speculative indirect
2562 branches. Requires a compiler with -mindirect-branch=thunk-extern
2563 support for full protection. The kernel may run slower.
2566 bool "Enable return-thunks"
2567 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2568 select OBJTOOL if HAVE_OBJTOOL
2571 Compile the kernel with the return-thunks compiler option to guard
2572 against kernel-to-user data leaks by avoiding return speculation.
2573 Requires a compiler with -mfunction-return=thunk-extern
2574 support for full protection. The kernel may run slower.
2576 config CPU_UNRET_ENTRY
2577 bool "Enable UNRET on kernel entry"
2578 depends on CPU_SUP_AMD && RETHUNK && X86_64
2581 Compile the kernel with support for the retbleed=unret mitigation.
2583 config CALL_DEPTH_TRACKING
2584 bool "Mitigate RSB underflow with call depth tracking"
2585 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2586 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2590 Compile the kernel with call depth tracking to mitigate the Intel
2591 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2592 mitigation is off by default and needs to be enabled on the
2593 kernel command line via the retbleed=stuff option. For
2594 non-affected systems the overhead of this option is marginal as
2595 the call depth tracking is using run-time generated call thunks
2596 in a compiler generated padding area and call patching. This
2597 increases text size by ~5%. For non affected systems this space
2598 is unused. On affected SKL systems this results in a significant
2599 performance gain over the IBRS mitigation.
2601 config CALL_THUNKS_DEBUG
2602 bool "Enable call thunks and call depth tracking debugging"
2603 depends on CALL_DEPTH_TRACKING
2604 select FUNCTION_ALIGNMENT_32B
2607 Enable call/ret counters for imbalance detection and build in
2608 a noisy dmesg about callthunks generation and call patching for
2609 trouble shooting. The debug prints need to be enabled on the
2610 kernel command line with 'debug-callthunks'.
2611 Only enable this when you are debugging call thunks as this
2612 creates a noticeable runtime overhead. If unsure say N.
2614 config CPU_IBPB_ENTRY
2615 bool "Enable IBPB on kernel entry"
2616 depends on CPU_SUP_AMD && X86_64
2619 Compile the kernel with support for the retbleed=ibpb mitigation.
2621 config CPU_IBRS_ENTRY
2622 bool "Enable IBRS on kernel entry"
2623 depends on CPU_SUP_INTEL && X86_64
2626 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2627 This mitigates both spectre_v2 and retbleed at great cost to
2631 bool "Mitigate Straight-Line-Speculation"
2632 depends on CC_HAS_SLS && X86_64
2633 select OBJTOOL if HAVE_OBJTOOL
2636 Compile the kernel with straight-line-speculation options to guard
2637 against straight line speculation. The kernel image might be slightly
2642 config ARCH_HAS_ADD_PAGES
2644 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2646 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2649 menu "Power management and ACPI options"
2651 config ARCH_HIBERNATION_HEADER
2653 depends on HIBERNATION
2655 source "kernel/power/Kconfig"
2657 source "drivers/acpi/Kconfig"
2664 tristate "APM (Advanced Power Management) BIOS support"
2665 depends on X86_32 && PM_SLEEP
2667 APM is a BIOS specification for saving power using several different
2668 techniques. This is mostly useful for battery powered laptops with
2669 APM compliant BIOSes. If you say Y here, the system time will be
2670 reset after a RESUME operation, the /proc/apm device will provide
2671 battery status information, and user-space programs will receive
2672 notification of APM "events" (e.g. battery status change).
2674 If you select "Y" here, you can disable actual use of the APM
2675 BIOS by passing the "apm=off" option to the kernel at boot time.
2677 Note that the APM support is almost completely disabled for
2678 machines with more than one CPU.
2680 In order to use APM, you will need supporting software. For location
2681 and more information, read <file:Documentation/power/apm-acpi.rst>
2682 and the Battery Powered Linux mini-HOWTO, available from
2683 <http://www.tldp.org/docs.html#howto>.
2685 This driver does not spin down disk drives (see the hdparm(8)
2686 manpage ("man 8 hdparm") for that), and it doesn't turn off
2687 VESA-compliant "green" monitors.
2689 This driver does not support the TI 4000M TravelMate and the ACER
2690 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2691 desktop machines also don't have compliant BIOSes, and this driver
2692 may cause those machines to panic during the boot phase.
2694 Generally, if you don't have a battery in your machine, there isn't
2695 much point in using this driver and you should say N. If you get
2696 random kernel OOPSes or reboots that don't seem to be related to
2697 anything, try disabling/enabling this option (or disabling/enabling
2700 Some other things you should try when experiencing seemingly random,
2703 1) make sure that you have enough swap space and that it is
2705 2) pass the "idle=poll" option to the kernel
2706 3) switch on floating point emulation in the kernel and pass
2707 the "no387" option to the kernel
2708 4) pass the "floppy=nodma" option to the kernel
2709 5) pass the "mem=4M" option to the kernel (thereby disabling
2710 all but the first 4 MB of RAM)
2711 6) make sure that the CPU is not over clocked.
2712 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2713 8) disable the cache from your BIOS settings
2714 9) install a fan for the video card or exchange video RAM
2715 10) install a better fan for the CPU
2716 11) exchange RAM chips
2717 12) exchange the motherboard.
2719 To compile this driver as a module, choose M here: the
2720 module will be called apm.
2724 config APM_IGNORE_USER_SUSPEND
2725 bool "Ignore USER SUSPEND"
2727 This option will ignore USER SUSPEND requests. On machines with a
2728 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2729 series notebooks, it is necessary to say Y because of a BIOS bug.
2731 config APM_DO_ENABLE
2732 bool "Enable PM at boot time"
2734 Enable APM features at boot time. From page 36 of the APM BIOS
2735 specification: "When disabled, the APM BIOS does not automatically
2736 power manage devices, enter the Standby State, enter the Suspend
2737 State, or take power saving steps in response to CPU Idle calls."
2738 This driver will make CPU Idle calls when Linux is idle (unless this
2739 feature is turned off -- see "Do CPU IDLE calls", below). This
2740 should always save battery power, but more complicated APM features
2741 will be dependent on your BIOS implementation. You may need to turn
2742 this option off if your computer hangs at boot time when using APM
2743 support, or if it beeps continuously instead of suspending. Turn
2744 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2745 T400CDT. This is off by default since most machines do fine without
2750 bool "Make CPU Idle calls when idle"
2752 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2753 On some machines, this can activate improved power savings, such as
2754 a slowed CPU clock rate, when the machine is idle. These idle calls
2755 are made after the idle loop has run for some length of time (e.g.,
2756 333 mS). On some machines, this will cause a hang at boot time or
2757 whenever the CPU becomes idle. (On machines with more than one CPU,
2758 this option does nothing.)
2760 config APM_DISPLAY_BLANK
2761 bool "Enable console blanking using APM"
2763 Enable console blanking using the APM. Some laptops can use this to
2764 turn off the LCD backlight when the screen blanker of the Linux
2765 virtual console blanks the screen. Note that this is only used by
2766 the virtual console screen blanker, and won't turn off the backlight
2767 when using the X Window system. This also doesn't have anything to
2768 do with your VESA-compliant power-saving monitor. Further, this
2769 option doesn't work for all laptops -- it might not turn off your
2770 backlight at all, or it might print a lot of errors to the console,
2771 especially if you are using gpm.
2773 config APM_ALLOW_INTS
2774 bool "Allow interrupts during APM BIOS calls"
2776 Normally we disable external interrupts while we are making calls to
2777 the APM BIOS as a measure to lessen the effects of a badly behaving
2778 BIOS implementation. The BIOS should reenable interrupts if it
2779 needs to. Unfortunately, some BIOSes do not -- especially those in
2780 many of the newer IBM Thinkpads. If you experience hangs when you
2781 suspend, try setting this to Y. Otherwise, say N.
2785 source "drivers/cpufreq/Kconfig"
2787 source "drivers/cpuidle/Kconfig"
2789 source "drivers/idle/Kconfig"
2793 menu "Bus options (PCI etc.)"
2796 prompt "PCI access mode"
2797 depends on X86_32 && PCI
2800 On PCI systems, the BIOS can be used to detect the PCI devices and
2801 determine their configuration. However, some old PCI motherboards
2802 have BIOS bugs and may crash if this is done. Also, some embedded
2803 PCI-based systems don't have any BIOS at all. Linux can also try to
2804 detect the PCI hardware directly without using the BIOS.
2806 With this option, you can specify how Linux should detect the
2807 PCI devices. If you choose "BIOS", the BIOS will be used,
2808 if you choose "Direct", the BIOS won't be used, and if you
2809 choose "MMConfig", then PCI Express MMCONFIG will be used.
2810 If you choose "Any", the kernel will try MMCONFIG, then the
2811 direct access method and falls back to the BIOS if that doesn't
2812 work. If unsure, go with the default, which is "Any".
2817 config PCI_GOMMCONFIG
2834 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2836 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2839 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2842 bool "Support mmconfig PCI config space access" if X86_64
2844 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2845 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2849 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2853 depends on PCI && XEN
2855 config MMCONF_FAM10H
2857 depends on X86_64 && PCI_MMCONFIG && ACPI
2859 config PCI_CNB20LE_QUIRK
2860 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2863 Read the PCI windows out of the CNB20LE host bridge. This allows
2864 PCI hotplug to work on systems with the CNB20LE chipset which do
2867 There's no public spec for this chipset, and this functionality
2868 is known to be incomplete.
2870 You should say N unless you know you need this.
2873 bool "ISA bus support on modern systems" if EXPERT
2875 Expose ISA bus device drivers and options available for selection and
2876 configuration. Enable this option if your target machine has an ISA
2877 bus. ISA is an older system, displaced by PCI and newer bus
2878 architectures -- if your target machine is modern, it probably does
2879 not have an ISA bus.
2883 # x86_64 have no ISA slots, but can have ISA-style DMA.
2885 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2888 Enables ISA-style DMA support for devices requiring such controllers.
2896 Find out whether you have ISA slots on your motherboard. ISA is the
2897 name of a bus system, i.e. the way the CPU talks to the other stuff
2898 inside your box. Other bus systems are PCI, EISA, MicroChannel
2899 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2900 newer boards don't support it. If you have ISA, say Y, otherwise N.
2903 tristate "NatSemi SCx200 support"
2905 This provides basic support for National Semiconductor's
2906 (now AMD's) Geode processors. The driver probes for the
2907 PCI-IDs of several on-chip devices, so its a good dependency
2908 for other scx200_* drivers.
2910 If compiled as a module, the driver is named scx200.
2912 config SCx200HR_TIMER
2913 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2917 This driver provides a clocksource built upon the on-chip
2918 27MHz high-resolution timer. Its also a workaround for
2919 NSC Geode SC-1100's buggy TSC, which loses time when the
2920 processor goes idle (as is done by the scheduler). The
2921 other workaround is idle=poll boot option.
2924 bool "One Laptop Per Child support"
2932 Add support for detecting the unique features of the OLPC
2936 bool "OLPC XO-1 Power Management"
2937 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2939 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2942 bool "OLPC XO-1 Real Time Clock"
2943 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2945 Add support for the XO-1 real time clock, which can be used as a
2946 programmable wakeup source.
2949 bool "OLPC XO-1 SCI extras"
2950 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2954 Add support for SCI-based features of the OLPC XO-1 laptop:
2955 - EC-driven system wakeups
2959 - AC adapter status updates
2960 - Battery status updates
2962 config OLPC_XO15_SCI
2963 bool "OLPC XO-1.5 SCI extras"
2964 depends on OLPC && ACPI
2967 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2968 - EC-driven system wakeups
2969 - AC adapter status updates
2970 - Battery status updates
2973 bool "PCEngines ALIX System Support (LED setup)"
2976 This option enables system support for the PCEngines ALIX.
2977 At present this just sets up LEDs for GPIO control on
2978 ALIX2/3/6 boards. However, other system specific setup should
2981 Note: You must still enable the drivers for GPIO and LED support
2982 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2984 Note: You have to set alix.force=1 for boards with Award BIOS.
2987 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2990 This option enables system support for the Soekris Engineering net5501.
2993 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2997 This option enables system support for the Traverse Technologies GEOS.
3000 bool "Technologic Systems TS-5500 platform support"
3002 select CHECK_SIGNATURE
3006 This option enables system support for the Technologic Systems TS-5500.
3012 depends on CPU_SUP_AMD && PCI
3016 menu "Binary Emulations"
3018 config IA32_EMULATION
3019 bool "IA32 Emulation"
3021 select ARCH_WANT_OLD_COMPAT_IPC
3023 select COMPAT_OLD_SIGACTION
3025 Include code to run legacy 32-bit programs under a
3026 64-bit kernel. You should likely turn this on, unless you're
3027 100% sure that you don't have any 32-bit programs left.
3030 bool "x32 ABI for 64-bit mode"
3032 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3033 # compressed debug sections to x86_x32 properly:
3034 # https://github.com/ClangBuiltLinux/linux/issues/514
3035 # https://github.com/ClangBuiltLinux/linux/issues/1141
3036 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3038 Include code to run binaries for the x32 native 32-bit ABI
3039 for 64-bit processors. An x32 process gets access to the
3040 full 64-bit register file and wide data path while leaving
3041 pointers at 32 bits for smaller memory footprint.
3045 depends on IA32_EMULATION || X86_32
3047 select OLD_SIGSUSPEND3
3051 depends on IA32_EMULATION || X86_X32_ABI
3053 config COMPAT_FOR_U64_ALIGNMENT
3059 config HAVE_ATOMIC_IOMAP
3063 source "arch/x86/kvm/Kconfig"
3065 source "arch/x86/Kconfig.assembler"