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
165 select HAVE_ACPI_APEI if ACPI
166 select HAVE_ACPI_APEI_NMI if ACPI
167 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
168 select HAVE_ARCH_AUDITSYSCALL
169 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
170 select HAVE_ARCH_HUGE_VMALLOC if X86_64
171 select HAVE_ARCH_JUMP_LABEL
172 select HAVE_ARCH_JUMP_LABEL_RELATIVE
173 select HAVE_ARCH_KASAN if X86_64
174 select HAVE_ARCH_KASAN_VMALLOC if X86_64
175 select HAVE_ARCH_KFENCE
176 select HAVE_ARCH_KMSAN if X86_64
177 select HAVE_ARCH_KGDB
178 select HAVE_ARCH_MMAP_RND_BITS if MMU
179 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
180 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
181 select HAVE_ARCH_PREL32_RELOCATIONS
182 select HAVE_ARCH_SECCOMP_FILTER
183 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
184 select HAVE_ARCH_STACKLEAK
185 select HAVE_ARCH_TRACEHOOK
186 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
187 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
188 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
189 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
190 select HAVE_ARCH_VMAP_STACK if X86_64
191 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
192 select HAVE_ARCH_WITHIN_STACK_FRAMES
193 select HAVE_ASM_MODVERSIONS
194 select HAVE_CMPXCHG_DOUBLE
195 select HAVE_CMPXCHG_LOCAL
196 select HAVE_CONTEXT_TRACKING_USER if X86_64
197 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
198 select HAVE_C_RECORDMCOUNT
199 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
200 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
201 select HAVE_BUILDTIME_MCOUNT_SORT
202 select HAVE_DEBUG_KMEMLEAK
203 select HAVE_DMA_CONTIGUOUS
204 select HAVE_DYNAMIC_FTRACE
205 select HAVE_DYNAMIC_FTRACE_WITH_REGS
206 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
207 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
208 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
209 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
211 select HAVE_EFFICIENT_UNALIGNED_ACCESS
213 select HAVE_EXIT_THREAD
215 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
216 select HAVE_FTRACE_MCOUNT_RECORD
217 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
218 select HAVE_FUNCTION_TRACER
219 select HAVE_GCC_PLUGINS
220 select HAVE_HW_BREAKPOINT
221 select HAVE_IOREMAP_PROT
222 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
223 select HAVE_IRQ_TIME_ACCOUNTING
224 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
225 select HAVE_KERNEL_BZIP2
226 select HAVE_KERNEL_GZIP
227 select HAVE_KERNEL_LZ4
228 select HAVE_KERNEL_LZMA
229 select HAVE_KERNEL_LZO
230 select HAVE_KERNEL_XZ
231 select HAVE_KERNEL_ZSTD
233 select HAVE_KPROBES_ON_FTRACE
234 select HAVE_FUNCTION_ERROR_INJECTION
235 select HAVE_KRETPROBES
238 select HAVE_LIVEPATCH if X86_64
239 select HAVE_MIXED_BREAKPOINTS_REGS
240 select HAVE_MOD_ARCH_SPECIFIC
243 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
245 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
246 select HAVE_OBJTOOL if X86_64
247 select HAVE_OPTPROBES
248 select HAVE_PCSPKR_PLATFORM
249 select HAVE_PERF_EVENTS
250 select HAVE_PERF_EVENTS_NMI
251 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
253 select HAVE_PERF_REGS
254 select HAVE_PERF_USER_STACK_DUMP
255 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
256 select MMU_GATHER_MERGE_VMAS
257 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
258 select HAVE_REGS_AND_STACK_ACCESS_API
259 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
260 select HAVE_FUNCTION_ARG_ACCESS_API
261 select HAVE_SETUP_PER_CPU_AREA
262 select HAVE_SOFTIRQ_ON_OWN_STACK
263 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
264 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
265 select HAVE_STATIC_CALL
266 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
267 select HAVE_PREEMPT_DYNAMIC_CALL
269 select HAVE_RUST if X86_64
270 select HAVE_SYSCALL_TRACEPOINTS
271 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
272 select HAVE_UNSTABLE_SCHED_CLOCK
273 select HAVE_USER_RETURN_NOTIFIER
274 select HAVE_GENERIC_VDSO
275 select HOTPLUG_SMT if SMP
276 select IRQ_FORCED_THREADING
277 select NEED_PER_CPU_EMBED_FIRST_CHUNK
278 select NEED_PER_CPU_PAGE_FIRST_CHUNK
279 select NEED_SG_DMA_LENGTH
280 select PCI_DOMAINS if PCI
281 select PCI_LOCKLESS_CONFIG if PCI
284 select RTC_MC146818_LIB
286 select SYSCTL_EXCEPTION_TRACE
287 select THREAD_INFO_IN_TASK
288 select TRACE_IRQFLAGS_SUPPORT
289 select TRACE_IRQFLAGS_NMI_SUPPORT
290 select USER_STACKTRACE_SUPPORT
291 select HAVE_ARCH_KCSAN if X86_64
292 select X86_FEATURE_NAMES if PROC_FS
293 select PROC_PID_ARCH_STATUS if PROC_FS
294 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
295 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
296 select FUNCTION_ALIGNMENT_4B
297 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
298 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
300 config INSTRUCTION_DECODER
302 depends on KPROBES || PERF_EVENTS || UPROBES
306 default "elf32-i386" if X86_32
307 default "elf64-x86-64" if X86_64
309 config LOCKDEP_SUPPORT
312 config STACKTRACE_SUPPORT
318 config ARCH_MMAP_RND_BITS_MIN
322 config ARCH_MMAP_RND_BITS_MAX
326 config ARCH_MMAP_RND_COMPAT_BITS_MIN
329 config ARCH_MMAP_RND_COMPAT_BITS_MAX
335 config GENERIC_ISA_DMA
337 depends on ISA_DMA_API
341 default y if KMSAN || KASAN
346 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
348 config GENERIC_BUG_RELATIVE_POINTERS
351 config ARCH_MAY_HAVE_PC_FDC
353 depends on ISA_DMA_API
355 config GENERIC_CALIBRATE_DELAY
358 config ARCH_HAS_CPU_RELAX
361 config ARCH_HIBERNATION_POSSIBLE
364 config ARCH_SUSPEND_POSSIBLE
370 config KASAN_SHADOW_OFFSET
373 default 0xdffffc0000000000
375 config HAVE_INTEL_TXT
377 depends on INTEL_IOMMU && ACPI
381 depends on X86_32 && SMP
385 depends on X86_64 && SMP
387 config ARCH_SUPPORTS_UPROBES
390 config FIX_EARLYCON_MEM
393 config DYNAMIC_PHYSICAL_MASK
396 config PGTABLE_LEVELS
398 default 5 if X86_5LEVEL
403 config CC_HAS_SANE_STACKPROTECTOR
405 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
406 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
408 We have to make sure stack protector is unconditionally disabled if
409 the compiler produces broken code or if it does not let us control
410 the segment on 32-bit kernels.
412 menu "Processor type and features"
415 bool "Symmetric multi-processing support"
417 This enables support for systems with more than one CPU. If you have
418 a system with only one CPU, say N. If you have a system with more
421 If you say N here, the kernel will run on uni- and multiprocessor
422 machines, but will use only one CPU of a multiprocessor machine. If
423 you say Y here, the kernel will run on many, but not all,
424 uniprocessor machines. On a uniprocessor machine, the kernel
425 will run faster if you say N here.
427 Note that if you say Y here and choose architecture "586" or
428 "Pentium" under "Processor family", the kernel will not work on 486
429 architectures. Similarly, multiprocessor kernels for the "PPro"
430 architecture may not work on all Pentium based boards.
432 People using multiprocessor machines who say Y here should also say
433 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
434 Management" code will be disabled if you say Y here.
436 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
437 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
438 <http://www.tldp.org/docs.html#howto>.
440 If you don't know what to do here, say N.
442 config X86_FEATURE_NAMES
443 bool "Processor feature human-readable names" if EMBEDDED
446 This option compiles in a table of x86 feature bits and corresponding
447 names. This is required to support /proc/cpuinfo and a few kernel
448 messages. You can disable this to save space, at the expense of
449 making those few kernel messages show numeric feature bits instead.
454 bool "Support x2apic"
455 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
457 This enables x2apic support on CPUs that have this feature.
459 This allows 32-bit apic IDs (so it can support very large systems),
460 and accesses the local apic via MSRs not via mmio.
462 Some Intel systems circa 2022 and later are locked into x2APIC mode
463 and can not fall back to the legacy APIC modes if SGX or TDX are
464 enabled in the BIOS. They will boot with very reduced functionality
465 without enabling this option.
467 If you don't know what to do here, say N.
470 bool "Enable MPS table" if ACPI
472 depends on X86_LOCAL_APIC
474 For old smp systems that do not have proper acpi support. Newer systems
475 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
479 depends on X86_GOLDFISH
481 config X86_CPU_RESCTRL
482 bool "x86 CPU resource control support"
483 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
485 select PROC_CPU_RESCTRL if PROC_FS
487 Enable x86 CPU resource control support.
489 Provide support for the allocation and monitoring of system resources
492 Intel calls this Intel Resource Director Technology
493 (Intel(R) RDT). More information about RDT can be found in the
494 Intel x86 Architecture Software Developer Manual.
496 AMD calls this AMD Platform Quality of Service (AMD QoS).
497 More information about AMD QoS can be found in the AMD64 Technology
498 Platform Quality of Service Extensions manual.
504 bool "Support for big SMP systems with more than 8 CPUs"
507 This option is needed for the systems that have more than 8 CPUs.
509 config X86_EXTENDED_PLATFORM
510 bool "Support for extended (non-PC) x86 platforms"
513 If you disable this option then the kernel will only support
514 standard PC platforms. (which covers the vast majority of
517 If you enable this option then you'll be able to select support
518 for the following (non-PC) 32 bit x86 platforms:
519 Goldfish (Android emulator)
522 SGI 320/540 (Visual Workstation)
523 STA2X11-based (e.g. Northville)
524 Moorestown MID devices
526 If you have one of these systems, or if you want to build a
527 generic distribution kernel, say Y here - otherwise say N.
531 config X86_EXTENDED_PLATFORM
532 bool "Support for extended (non-PC) x86 platforms"
535 If you disable this option then the kernel will only support
536 standard PC platforms. (which covers the vast majority of
539 If you enable this option then you'll be able to select support
540 for the following (non-PC) 64 bit x86 platforms:
545 If you have one of these systems, or if you want to build a
546 generic distribution kernel, say Y here - otherwise say N.
548 # This is an alphabetically sorted list of 64 bit extended platforms
549 # Please maintain the alphabetic order if and when there are additions
551 bool "Numascale NumaChip"
553 depends on X86_EXTENDED_PLATFORM
556 depends on X86_X2APIC
557 depends on PCI_MMCONFIG
559 Adds support for Numascale NumaChip large-SMP systems. Needed to
560 enable more than ~168 cores.
561 If you don't have one of these, you should say N here.
565 select HYPERVISOR_GUEST
567 depends on X86_64 && PCI
568 depends on X86_EXTENDED_PLATFORM
571 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
572 supposed to run on these EM64T-based machines. Only choose this option
573 if you have one of these machines.
576 bool "SGI Ultraviolet"
578 depends on X86_EXTENDED_PLATFORM
581 depends on KEXEC_CORE
582 depends on X86_X2APIC
585 This option is needed in order to support SGI Ultraviolet systems.
586 If you don't have one of these, you should say N here.
588 # Following is an alphabetically sorted list of 32 bit extended platforms
589 # Please maintain the alphabetic order if and when there are additions
592 bool "Goldfish (Virtual Platform)"
593 depends on X86_EXTENDED_PLATFORM
595 Enable support for the Goldfish virtual platform used primarily
596 for Android development. Unless you are building for the Android
597 Goldfish emulator say N here.
600 bool "CE4100 TV platform"
602 depends on PCI_GODIRECT
603 depends on X86_IO_APIC
605 depends on X86_EXTENDED_PLATFORM
606 select X86_REBOOTFIXUPS
608 select OF_EARLY_FLATTREE
610 Select for the Intel CE media processor (CE4100) SOC.
611 This option compiles in support for the CE4100 SOC for settop
612 boxes and media devices.
615 bool "Intel MID platform support"
616 depends on X86_EXTENDED_PLATFORM
617 depends on X86_PLATFORM_DEVICES
619 depends on X86_64 || (PCI_GOANY && X86_32)
620 depends on X86_IO_APIC
625 Select to build a kernel capable of supporting Intel MID (Mobile
626 Internet Device) platform systems which do not have the PCI legacy
627 interfaces. If you are building for a PC class system say N here.
629 Intel MID platforms are based on an Intel processor and chipset which
630 consume less power than most of the x86 derivatives.
632 config X86_INTEL_QUARK
633 bool "Intel Quark platform support"
635 depends on X86_EXTENDED_PLATFORM
636 depends on X86_PLATFORM_DEVICES
640 depends on X86_IO_APIC
645 Select to include support for Quark X1000 SoC.
646 Say Y here if you have a Quark based system such as the Arduino
647 compatible Intel Galileo.
649 config X86_INTEL_LPSS
650 bool "Intel Low Power Subsystem Support"
651 depends on X86 && ACPI && PCI
656 Select to build support for Intel Low Power Subsystem such as
657 found on Intel Lynxpoint PCH. Selecting this option enables
658 things like clock tree (common clock framework) and pincontrol
659 which are needed by the LPSS peripheral drivers.
661 config X86_AMD_PLATFORM_DEVICE
662 bool "AMD ACPI2Platform devices support"
667 Select to interpret AMD specific ACPI device to platform device
668 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
669 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
670 implemented under PINCTRL subsystem.
673 tristate "Intel SoC IOSF Sideband support for SoC platforms"
676 This option enables sideband register access support for Intel SoC
677 platforms. On these platforms the IOSF sideband is used in lieu of
678 MSR's for some register accesses, mostly but not limited to thermal
679 and power. Drivers may query the availability of this device to
680 determine if they need the sideband in order to work on these
681 platforms. The sideband is available on the following SoC products.
682 This list is not meant to be exclusive.
687 You should say Y if you are running a kernel on one of these SoC's.
689 config IOSF_MBI_DEBUG
690 bool "Enable IOSF sideband access through debugfs"
691 depends on IOSF_MBI && DEBUG_FS
693 Select this option to expose the IOSF sideband access registers (MCR,
694 MDR, MCRX) through debugfs to write and read register information from
695 different units on the SoC. This is most useful for obtaining device
696 state information for debug and analysis. As this is a general access
697 mechanism, users of this option would have specific knowledge of the
698 device they want to access.
700 If you don't require the option or are in doubt, say N.
703 bool "RDC R-321x SoC"
705 depends on X86_EXTENDED_PLATFORM
707 select X86_REBOOTFIXUPS
709 This option is needed for RDC R-321x system-on-chip, also known
711 If you don't have one of these chips, you should say N here.
713 config X86_32_NON_STANDARD
714 bool "Support non-standard 32-bit SMP architectures"
715 depends on X86_32 && SMP
716 depends on X86_EXTENDED_PLATFORM
718 This option compiles in the bigsmp and STA2X11 default
719 subarchitectures. It is intended for a generic binary
720 kernel. If you select them all, kernel will probe it one by
721 one and will fallback to default.
723 # Alphabetically sorted list of Non standard 32 bit platforms
725 config X86_SUPPORTS_MEMORY_FAILURE
727 # MCE code calls memory_failure():
729 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
730 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
731 depends on X86_64 || !SPARSEMEM
732 select ARCH_SUPPORTS_MEMORY_FAILURE
735 bool "STA2X11 Companion Chip Support"
736 depends on X86_32_NON_STANDARD && PCI
741 This adds support for boards based on the STA2X11 IO-Hub,
742 a.k.a. "ConneXt". The chip is used in place of the standard
743 PC chipset, so all "standard" peripherals are missing. If this
744 option is selected the kernel will still be able to boot on
745 standard PC machines.
748 tristate "Eurobraille/Iris poweroff module"
751 The Iris machines from EuroBraille do not have APM or ACPI support
752 to shut themselves down properly. A special I/O sequence is
753 needed to do so, which is what this module does at
756 This is only for Iris machines from EuroBraille.
760 config SCHED_OMIT_FRAME_POINTER
762 prompt "Single-depth WCHAN output"
765 Calculate simpler /proc/<PID>/wchan values. If this option
766 is disabled then wchan values will recurse back to the
767 caller function. This provides more accurate wchan values,
768 at the expense of slightly more scheduling overhead.
770 If in doubt, say "Y".
772 menuconfig HYPERVISOR_GUEST
773 bool "Linux guest support"
775 Say Y here to enable options for running Linux under various hyper-
776 visors. This option enables basic hypervisor detection and platform
779 If you say N, all options in this submenu will be skipped and
780 disabled, and Linux guest support won't be built in.
785 bool "Enable paravirtualization code"
786 depends on HAVE_STATIC_CALL
788 This changes the kernel so it can modify itself when it is run
789 under a hypervisor, potentially improving performance significantly
790 over full virtualization. However, when run without a hypervisor
791 the kernel is theoretically slower and slightly larger.
796 config PARAVIRT_DEBUG
797 bool "paravirt-ops debugging"
798 depends on PARAVIRT && DEBUG_KERNEL
800 Enable to debug paravirt_ops internals. Specifically, BUG if
801 a paravirt_op is missing when it is called.
803 config PARAVIRT_SPINLOCKS
804 bool "Paravirtualization layer for spinlocks"
805 depends on PARAVIRT && SMP
807 Paravirtualized spinlocks allow a pvops backend to replace the
808 spinlock implementation with something virtualization-friendly
809 (for example, block the virtual CPU rather than spinning).
811 It has a minimal impact on native kernels and gives a nice performance
812 benefit on paravirtualized KVM / Xen kernels.
814 If you are unsure how to answer this question, answer Y.
816 config X86_HV_CALLBACK_VECTOR
819 source "arch/x86/xen/Kconfig"
822 bool "KVM Guest support (including kvmclock)"
824 select PARAVIRT_CLOCK
825 select ARCH_CPUIDLE_HALTPOLL
826 select X86_HV_CALLBACK_VECTOR
829 This option enables various optimizations for running under the KVM
830 hypervisor. It includes a paravirtualized clock, so that instead
831 of relying on a PIT (or probably other) emulation by the
832 underlying device model, the host provides the guest with
833 timing infrastructure such as time of day, and system time
835 config ARCH_CPUIDLE_HALTPOLL
837 prompt "Disable host haltpoll when loading haltpoll driver"
839 If virtualized under KVM, disable host haltpoll.
842 bool "Support for running PVH guests"
844 This option enables the PVH entry point for guest virtual machines
845 as specified in the x86/HVM direct boot ABI.
847 config PARAVIRT_TIME_ACCOUNTING
848 bool "Paravirtual steal time accounting"
851 Select this option to enable fine granularity task steal time
852 accounting. Time spent executing other tasks in parallel with
853 the current vCPU is discounted from the vCPU power. To account for
854 that, there can be a small performance impact.
856 If in doubt, say N here.
858 config PARAVIRT_CLOCK
861 config JAILHOUSE_GUEST
862 bool "Jailhouse non-root cell support"
863 depends on X86_64 && PCI
866 This option allows to run Linux as guest in a Jailhouse non-root
867 cell. You can leave this option disabled if you only want to start
868 Jailhouse and run Linux afterwards in the root cell.
871 bool "ACRN Guest support"
873 select X86_HV_CALLBACK_VECTOR
875 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
876 a flexible, lightweight reference open-source hypervisor, built with
877 real-time and safety-criticality in mind. It is built for embedded
878 IOT with small footprint and real-time features. More details can be
879 found in https://projectacrn.org/.
881 config INTEL_TDX_GUEST
882 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
883 depends on X86_64 && CPU_SUP_INTEL
884 depends on X86_X2APIC
885 select ARCH_HAS_CC_PLATFORM
886 select X86_MEM_ENCRYPT
889 Support running as a guest under Intel TDX. Without this support,
890 the guest kernel can not boot or run under TDX.
891 TDX includes memory encryption and integrity capabilities
892 which protect the confidentiality and integrity of guest
893 memory contents and CPU state. TDX guests are protected from
894 some attacks from the VMM.
896 endif # HYPERVISOR_GUEST
898 source "arch/x86/Kconfig.cpu"
902 prompt "HPET Timer Support" if X86_32
904 Use the IA-PC HPET (High Precision Event Timer) to manage
905 time in preference to the PIT and RTC, if a HPET is
907 HPET is the next generation timer replacing legacy 8254s.
908 The HPET provides a stable time base on SMP
909 systems, unlike the TSC, but it is more expensive to access,
910 as it is off-chip. The interface used is documented
911 in the HPET spec, revision 1.
913 You can safely choose Y here. However, HPET will only be
914 activated if the platform and the BIOS support this feature.
915 Otherwise the 8254 will be used for timing services.
917 Choose N to continue using the legacy 8254 timer.
919 config HPET_EMULATE_RTC
921 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
923 # Mark as expert because too many people got it wrong.
924 # The code disables itself when not needed.
927 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
928 bool "Enable DMI scanning" if EXPERT
930 Enabled scanning of DMI to identify machine quirks. Say Y
931 here unless you have verified that your setup is not
932 affected by entries in the DMI blacklist. Required by PNP
936 bool "Old AMD GART IOMMU support"
940 depends on X86_64 && PCI && AMD_NB
942 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
943 GART based hardware IOMMUs.
945 The GART supports full DMA access for devices with 32-bit access
946 limitations, on systems with more than 3 GB. This is usually needed
947 for USB, sound, many IDE/SATA chipsets and some other devices.
949 Newer systems typically have a modern AMD IOMMU, supported via
950 the CONFIG_AMD_IOMMU=y config option.
952 In normal configurations this driver is only active when needed:
953 there's more than 3 GB of memory and the system contains a
954 32-bit limited device.
958 config BOOT_VESA_SUPPORT
961 If true, at least one selected framebuffer driver can take advantage
962 of VESA video modes set at an early boot stage via the vga= parameter.
965 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
966 depends on X86_64 && SMP && DEBUG_KERNEL
967 select CPUMASK_OFFSTACK
969 Enable maximum number of CPUS and NUMA Nodes for this architecture.
973 # The maximum number of CPUs supported:
975 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
976 # and which can be configured interactively in the
977 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
979 # The ranges are different on 32-bit and 64-bit kernels, depending on
980 # hardware capabilities and scalability features of the kernel.
982 # ( If MAXSMP is enabled we just use the highest possible value and disable
983 # interactive configuration. )
986 config NR_CPUS_RANGE_BEGIN
988 default NR_CPUS_RANGE_END if MAXSMP
992 config NR_CPUS_RANGE_END
995 default 64 if SMP && X86_BIGSMP
996 default 8 if SMP && !X86_BIGSMP
999 config NR_CPUS_RANGE_END
1002 default 8192 if SMP && CPUMASK_OFFSTACK
1003 default 512 if SMP && !CPUMASK_OFFSTACK
1006 config NR_CPUS_DEFAULT
1009 default 32 if X86_BIGSMP
1013 config NR_CPUS_DEFAULT
1016 default 8192 if MAXSMP
1021 int "Maximum number of CPUs" if SMP && !MAXSMP
1022 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1023 default NR_CPUS_DEFAULT
1025 This allows you to specify the maximum number of CPUs which this
1026 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1027 supported value is 8192, otherwise the maximum value is 512. The
1028 minimum value which makes sense is 2.
1030 This is purely to save memory: each supported CPU adds about 8KB
1031 to the kernel image.
1033 config SCHED_CLUSTER
1034 bool "Cluster scheduler support"
1038 Cluster scheduler support improves the CPU scheduler's decision
1039 making when dealing with machines that have clusters of CPUs.
1040 Cluster usually means a couple of CPUs which are placed closely
1041 by sharing mid-level caches, last-level cache tags or internal
1049 prompt "Multi-core scheduler support"
1052 Multi-core scheduler support improves the CPU scheduler's decision
1053 making when dealing with multi-core CPU chips at a cost of slightly
1054 increased overhead in some places. If unsure say N here.
1056 config SCHED_MC_PRIO
1057 bool "CPU core priorities scheduler support"
1058 depends on SCHED_MC && CPU_SUP_INTEL
1059 select X86_INTEL_PSTATE
1063 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1064 core ordering determined at manufacturing time, which allows
1065 certain cores to reach higher turbo frequencies (when running
1066 single threaded workloads) than others.
1068 Enabling this kernel feature teaches the scheduler about
1069 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1070 scheduler's CPU selection logic accordingly, so that higher
1071 overall system performance can be achieved.
1073 This feature will have no effect on CPUs without this feature.
1075 If unsure say Y here.
1079 depends on !SMP && X86_LOCAL_APIC
1082 bool "Local APIC support on uniprocessors" if !PCI_MSI
1084 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1086 A local APIC (Advanced Programmable Interrupt Controller) is an
1087 integrated interrupt controller in the CPU. If you have a single-CPU
1088 system which has a processor with a local APIC, you can say Y here to
1089 enable and use it. If you say Y here even though your machine doesn't
1090 have a local APIC, then the kernel will still run with no slowdown at
1091 all. The local APIC supports CPU-generated self-interrupts (timer,
1092 performance counters), and the NMI watchdog which detects hard
1095 config X86_UP_IOAPIC
1096 bool "IO-APIC support on uniprocessors"
1097 depends on X86_UP_APIC
1099 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1100 SMP-capable replacement for PC-style interrupt controllers. Most
1101 SMP systems and many recent uniprocessor systems have one.
1103 If you have a single-CPU system with an IO-APIC, you can say Y here
1104 to use it. If you say Y here even though your machine doesn't have
1105 an IO-APIC, then the kernel will still run with no slowdown at all.
1107 config X86_LOCAL_APIC
1109 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1110 select IRQ_DOMAIN_HIERARCHY
1114 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1116 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1117 bool "Reroute for broken boot IRQs"
1118 depends on X86_IO_APIC
1120 This option enables a workaround that fixes a source of
1121 spurious interrupts. This is recommended when threaded
1122 interrupt handling is used on systems where the generation of
1123 superfluous "boot interrupts" cannot be disabled.
1125 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1126 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1127 kernel does during interrupt handling). On chipsets where this
1128 boot IRQ generation cannot be disabled, this workaround keeps
1129 the original IRQ line masked so that only the equivalent "boot
1130 IRQ" is delivered to the CPUs. The workaround also tells the
1131 kernel to set up the IRQ handler on the boot IRQ line. In this
1132 way only one interrupt is delivered to the kernel. Otherwise
1133 the spurious second interrupt may cause the kernel to bring
1134 down (vital) interrupt lines.
1136 Only affects "broken" chipsets. Interrupt sharing may be
1137 increased on these systems.
1140 bool "Machine Check / overheating reporting"
1141 select GENERIC_ALLOCATOR
1144 Machine Check support allows the processor to notify the
1145 kernel if it detects a problem (e.g. overheating, data corruption).
1146 The action the kernel takes depends on the severity of the problem,
1147 ranging from warning messages to halting the machine.
1149 config X86_MCELOG_LEGACY
1150 bool "Support for deprecated /dev/mcelog character device"
1153 Enable support for /dev/mcelog which is needed by the old mcelog
1154 userspace logging daemon. Consider switching to the new generation
1157 config X86_MCE_INTEL
1159 prompt "Intel MCE features"
1160 depends on X86_MCE && X86_LOCAL_APIC
1162 Additional support for intel specific MCE features such as
1163 the thermal monitor.
1167 prompt "AMD MCE features"
1168 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1170 Additional support for AMD specific MCE features such as
1171 the DRAM Error Threshold.
1173 config X86_ANCIENT_MCE
1174 bool "Support for old Pentium 5 / WinChip machine checks"
1175 depends on X86_32 && X86_MCE
1177 Include support for machine check handling on old Pentium 5 or WinChip
1178 systems. These typically need to be enabled explicitly on the command
1181 config X86_MCE_THRESHOLD
1182 depends on X86_MCE_AMD || X86_MCE_INTEL
1185 config X86_MCE_INJECT
1186 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1187 tristate "Machine check injector support"
1189 Provide support for injecting machine checks for testing purposes.
1190 If you don't know what a machine check is and you don't do kernel
1191 QA it is safe to say n.
1193 source "arch/x86/events/Kconfig"
1195 config X86_LEGACY_VM86
1196 bool "Legacy VM86 support"
1199 This option allows user programs to put the CPU into V8086
1200 mode, which is an 80286-era approximation of 16-bit real mode.
1202 Some very old versions of X and/or vbetool require this option
1203 for user mode setting. Similarly, DOSEMU will use it if
1204 available to accelerate real mode DOS programs. However, any
1205 recent version of DOSEMU, X, or vbetool should be fully
1206 functional even without kernel VM86 support, as they will all
1207 fall back to software emulation. Nevertheless, if you are using
1208 a 16-bit DOS program where 16-bit performance matters, vm86
1209 mode might be faster than emulation and you might want to
1212 Note that any app that works on a 64-bit kernel is unlikely to
1213 need this option, as 64-bit kernels don't, and can't, support
1214 V8086 mode. This option is also unrelated to 16-bit protected
1215 mode and is not needed to run most 16-bit programs under Wine.
1217 Enabling this option increases the complexity of the kernel
1218 and slows down exception handling a tiny bit.
1220 If unsure, say N here.
1224 default X86_LEGACY_VM86
1227 bool "Enable support for 16-bit segments" if EXPERT
1229 depends on MODIFY_LDT_SYSCALL
1231 This option is required by programs like Wine to run 16-bit
1232 protected mode legacy code on x86 processors. Disabling
1233 this option saves about 300 bytes on i386, or around 6K text
1234 plus 16K runtime memory on x86-64,
1238 depends on X86_16BIT && X86_32
1242 depends on X86_16BIT && X86_64
1244 config X86_VSYSCALL_EMULATION
1245 bool "Enable vsyscall emulation" if EXPERT
1249 This enables emulation of the legacy vsyscall page. Disabling
1250 it is roughly equivalent to booting with vsyscall=none, except
1251 that it will also disable the helpful warning if a program
1252 tries to use a vsyscall. With this option set to N, offending
1253 programs will just segfault, citing addresses of the form
1256 This option is required by many programs built before 2013, and
1257 care should be used even with newer programs if set to N.
1259 Disabling this option saves about 7K of kernel size and
1260 possibly 4K of additional runtime pagetable memory.
1262 config X86_IOPL_IOPERM
1263 bool "IOPERM and IOPL Emulation"
1266 This enables the ioperm() and iopl() syscalls which are necessary
1267 for legacy applications.
1269 Legacy IOPL support is an overbroad mechanism which allows user
1270 space aside of accessing all 65536 I/O ports also to disable
1271 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1272 capabilities and permission from potentially active security
1275 The emulation restricts the functionality of the syscall to
1276 only allowing the full range I/O port access, but prevents the
1277 ability to disable interrupts from user space which would be
1278 granted if the hardware IOPL mechanism would be used.
1281 tristate "Toshiba Laptop support"
1284 This adds a driver to safely access the System Management Mode of
1285 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1286 not work on models with a Phoenix BIOS. The System Management Mode
1287 is used to set the BIOS and power saving options on Toshiba portables.
1289 For information on utilities to make use of this driver see the
1290 Toshiba Linux utilities web site at:
1291 <http://www.buzzard.org.uk/toshiba/>.
1293 Say Y if you intend to run this kernel on a Toshiba portable.
1296 config X86_REBOOTFIXUPS
1297 bool "Enable X86 board specific fixups for reboot"
1300 This enables chipset and/or board specific fixups to be done
1301 in order to get reboot to work correctly. This is only needed on
1302 some combinations of hardware and BIOS. The symptom, for which
1303 this config is intended, is when reboot ends with a stalled/hung
1306 Currently, the only fixup is for the Geode machines using
1307 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1309 Say Y if you want to enable the fixup. Currently, it's safe to
1310 enable this option even if you don't need it.
1314 bool "CPU microcode loading support"
1316 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1318 If you say Y here, you will be able to update the microcode on
1319 Intel and AMD processors. The Intel support is for the IA32 family,
1320 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1321 AMD support is for families 0x10 and later. You will obviously need
1322 the actual microcode binary data itself which is not shipped with
1325 The preferred method to load microcode from a detached initrd is described
1326 in Documentation/arch/x86/microcode.rst. For that you need to enable
1327 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1328 initrd for microcode blobs.
1330 In addition, you can build the microcode into the kernel. For that you
1331 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1334 config MICROCODE_INTEL
1335 bool "Intel microcode loading support"
1336 depends on CPU_SUP_INTEL && MICROCODE
1339 This options enables microcode patch loading support for Intel
1342 For the current Intel microcode data package go to
1343 <https://downloadcenter.intel.com> and search for
1344 'Linux Processor Microcode Data File'.
1346 config MICROCODE_AMD
1347 bool "AMD microcode loading support"
1348 depends on CPU_SUP_AMD && MICROCODE
1350 If you select this option, microcode patch loading support for AMD
1351 processors will be enabled.
1353 config MICROCODE_LATE_LOADING
1354 bool "Late microcode loading (DANGEROUS)"
1356 depends on MICROCODE
1358 Loading microcode late, when the system is up and executing instructions
1359 is a tricky business and should be avoided if possible. Just the sequence
1360 of synchronizing all cores and SMT threads is one fragile dance which does
1361 not guarantee that cores might not softlock after the loading. Therefore,
1362 use this at your own risk. Late loading taints the kernel too.
1365 tristate "/dev/cpu/*/msr - Model-specific register support"
1367 This device gives privileged processes access to the x86
1368 Model-Specific Registers (MSRs). It is a character device with
1369 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1370 MSR accesses are directed to a specific CPU on multi-processor
1374 tristate "/dev/cpu/*/cpuid - CPU information support"
1376 This device gives processes access to the x86 CPUID instruction to
1377 be executed on a specific processor. It is a character device
1378 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1382 prompt "High Memory Support"
1389 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1390 However, the address space of 32-bit x86 processors is only 4
1391 Gigabytes large. That means that, if you have a large amount of
1392 physical memory, not all of it can be "permanently mapped" by the
1393 kernel. The physical memory that's not permanently mapped is called
1396 If you are compiling a kernel which will never run on a machine with
1397 more than 1 Gigabyte total physical RAM, answer "off" here (default
1398 choice and suitable for most users). This will result in a "3GB/1GB"
1399 split: 3GB are mapped so that each process sees a 3GB virtual memory
1400 space and the remaining part of the 4GB virtual memory space is used
1401 by the kernel to permanently map as much physical memory as
1404 If the machine has between 1 and 4 Gigabytes physical RAM, then
1407 If more than 4 Gigabytes is used then answer "64GB" here. This
1408 selection turns Intel PAE (Physical Address Extension) mode on.
1409 PAE implements 3-level paging on IA32 processors. PAE is fully
1410 supported by Linux, PAE mode is implemented on all recent Intel
1411 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1412 then the kernel will not boot on CPUs that don't support PAE!
1414 The actual amount of total physical memory will either be
1415 auto detected or can be forced by using a kernel command line option
1416 such as "mem=256M". (Try "man bootparam" or see the documentation of
1417 your boot loader (lilo or loadlin) about how to pass options to the
1418 kernel at boot time.)
1420 If unsure, say "off".
1425 Select this if you have a 32-bit processor and between 1 and 4
1426 gigabytes of physical RAM.
1430 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1433 Select this if you have a 32-bit processor and more than 4
1434 gigabytes of physical RAM.
1439 prompt "Memory split" if EXPERT
1443 Select the desired split between kernel and user memory.
1445 If the address range available to the kernel is less than the
1446 physical memory installed, the remaining memory will be available
1447 as "high memory". Accessing high memory is a little more costly
1448 than low memory, as it needs to be mapped into the kernel first.
1449 Note that increasing the kernel address space limits the range
1450 available to user programs, making the address space there
1451 tighter. Selecting anything other than the default 3G/1G split
1452 will also likely make your kernel incompatible with binary-only
1455 If you are not absolutely sure what you are doing, leave this
1459 bool "3G/1G user/kernel split"
1460 config VMSPLIT_3G_OPT
1462 bool "3G/1G user/kernel split (for full 1G low memory)"
1464 bool "2G/2G user/kernel split"
1465 config VMSPLIT_2G_OPT
1467 bool "2G/2G user/kernel split (for full 2G low memory)"
1469 bool "1G/3G user/kernel split"
1474 default 0xB0000000 if VMSPLIT_3G_OPT
1475 default 0x80000000 if VMSPLIT_2G
1476 default 0x78000000 if VMSPLIT_2G_OPT
1477 default 0x40000000 if VMSPLIT_1G
1483 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1486 bool "PAE (Physical Address Extension) Support"
1487 depends on X86_32 && !HIGHMEM4G
1488 select PHYS_ADDR_T_64BIT
1491 PAE is required for NX support, and furthermore enables
1492 larger swapspace support for non-overcommit purposes. It
1493 has the cost of more pagetable lookup overhead, and also
1494 consumes more pagetable space per process.
1497 bool "Enable 5-level page tables support"
1499 select DYNAMIC_MEMORY_LAYOUT
1500 select SPARSEMEM_VMEMMAP
1503 5-level paging enables access to larger address space:
1504 up to 128 PiB of virtual address space and 4 PiB of
1505 physical address space.
1507 It will be supported by future Intel CPUs.
1509 A kernel with the option enabled can be booted on machines that
1510 support 4- or 5-level paging.
1512 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1517 config X86_DIRECT_GBPAGES
1521 Certain kernel features effectively disable kernel
1522 linear 1 GB mappings (even if the CPU otherwise
1523 supports them), so don't confuse the user by printing
1524 that we have them enabled.
1526 config X86_CPA_STATISTICS
1527 bool "Enable statistic for Change Page Attribute"
1530 Expose statistics about the Change Page Attribute mechanism, which
1531 helps to determine the effectiveness of preserving large and huge
1532 page mappings when mapping protections are changed.
1534 config X86_MEM_ENCRYPT
1535 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1536 select DYNAMIC_PHYSICAL_MASK
1539 config AMD_MEM_ENCRYPT
1540 bool "AMD Secure Memory Encryption (SME) support"
1541 depends on X86_64 && CPU_SUP_AMD
1542 select DMA_COHERENT_POOL
1543 select ARCH_USE_MEMREMAP_PROT
1544 select INSTRUCTION_DECODER
1545 select ARCH_HAS_CC_PLATFORM
1546 select X86_MEM_ENCRYPT
1548 Say yes to enable support for the encryption of system memory.
1549 This requires an AMD processor that supports Secure Memory
1552 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1553 bool "Activate AMD Secure Memory Encryption (SME) by default"
1554 depends on AMD_MEM_ENCRYPT
1556 Say yes to have system memory encrypted by default if running on
1557 an AMD processor that supports Secure Memory Encryption (SME).
1559 If set to Y, then the encryption of system memory can be
1560 deactivated with the mem_encrypt=off command line option.
1562 If set to N, then the encryption of system memory can be
1563 activated with the mem_encrypt=on command line option.
1565 # Common NUMA Features
1567 bool "NUMA Memory Allocation and Scheduler Support"
1569 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1570 default y if X86_BIGSMP
1571 select USE_PERCPU_NUMA_NODE_ID
1573 Enable NUMA (Non-Uniform Memory Access) support.
1575 The kernel will try to allocate memory used by a CPU on the
1576 local memory controller of the CPU and add some more
1577 NUMA awareness to the kernel.
1579 For 64-bit this is recommended if the system is Intel Core i7
1580 (or later), AMD Opteron, or EM64T NUMA.
1582 For 32-bit this is only needed if you boot a 32-bit
1583 kernel on a 64-bit NUMA platform.
1585 Otherwise, you should say N.
1589 prompt "Old style AMD Opteron NUMA detection"
1590 depends on X86_64 && NUMA && PCI
1592 Enable AMD NUMA node topology detection. You should say Y here if
1593 you have a multi processor AMD system. This uses an old method to
1594 read the NUMA configuration directly from the builtin Northbridge
1595 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1596 which also takes priority if both are compiled in.
1598 config X86_64_ACPI_NUMA
1600 prompt "ACPI NUMA detection"
1601 depends on X86_64 && NUMA && ACPI && PCI
1604 Enable ACPI SRAT based node topology detection.
1607 bool "NUMA emulation"
1610 Enable NUMA emulation. A flat machine will be split
1611 into virtual nodes when booted with "numa=fake=N", where N is the
1612 number of nodes. This is only useful for debugging.
1615 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1617 default "10" if MAXSMP
1618 default "6" if X86_64
1622 Specify the maximum number of NUMA Nodes available on the target
1623 system. Increases memory reserved to accommodate various tables.
1625 config ARCH_FLATMEM_ENABLE
1627 depends on X86_32 && !NUMA
1629 config ARCH_SPARSEMEM_ENABLE
1631 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1632 select SPARSEMEM_STATIC if X86_32
1633 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1635 config ARCH_SPARSEMEM_DEFAULT
1636 def_bool X86_64 || (NUMA && X86_32)
1638 config ARCH_SELECT_MEMORY_MODEL
1640 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1642 config ARCH_MEMORY_PROBE
1643 bool "Enable sysfs memory/probe interface"
1644 depends on MEMORY_HOTPLUG
1646 This option enables a sysfs memory/probe interface for testing.
1647 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1648 If you are unsure how to answer this question, answer N.
1650 config ARCH_PROC_KCORE_TEXT
1652 depends on X86_64 && PROC_KCORE
1654 config ILLEGAL_POINTER_VALUE
1657 default 0xdead000000000000 if X86_64
1659 config X86_PMEM_LEGACY_DEVICE
1662 config X86_PMEM_LEGACY
1663 tristate "Support non-standard NVDIMMs and ADR protected memory"
1664 depends on PHYS_ADDR_T_64BIT
1666 select X86_PMEM_LEGACY_DEVICE
1667 select NUMA_KEEP_MEMINFO if NUMA
1670 Treat memory marked using the non-standard e820 type of 12 as used
1671 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1672 The kernel will offer these regions to the 'pmem' driver so
1673 they can be used for persistent storage.
1678 bool "Allocate 3rd-level pagetables from highmem"
1681 The VM uses one page table entry for each page of physical memory.
1682 For systems with a lot of RAM, this can be wasteful of precious
1683 low memory. Setting this option will put user-space page table
1684 entries in high memory.
1686 config X86_CHECK_BIOS_CORRUPTION
1687 bool "Check for low memory corruption"
1689 Periodically check for memory corruption in low memory, which
1690 is suspected to be caused by BIOS. Even when enabled in the
1691 configuration, it is disabled at runtime. Enable it by
1692 setting "memory_corruption_check=1" on the kernel command
1693 line. By default it scans the low 64k of memory every 60
1694 seconds; see the memory_corruption_check_size and
1695 memory_corruption_check_period parameters in
1696 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1698 When enabled with the default parameters, this option has
1699 almost no overhead, as it reserves a relatively small amount
1700 of memory and scans it infrequently. It both detects corruption
1701 and prevents it from affecting the running system.
1703 It is, however, intended as a diagnostic tool; if repeatable
1704 BIOS-originated corruption always affects the same memory,
1705 you can use memmap= to prevent the kernel from using that
1708 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1709 bool "Set the default setting of memory_corruption_check"
1710 depends on X86_CHECK_BIOS_CORRUPTION
1713 Set whether the default state of memory_corruption_check is
1716 config MATH_EMULATION
1718 depends on MODIFY_LDT_SYSCALL
1719 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1721 Linux can emulate a math coprocessor (used for floating point
1722 operations) if you don't have one. 486DX and Pentium processors have
1723 a math coprocessor built in, 486SX and 386 do not, unless you added
1724 a 487DX or 387, respectively. (The messages during boot time can
1725 give you some hints here ["man dmesg"].) Everyone needs either a
1726 coprocessor or this emulation.
1728 If you don't have a math coprocessor, you need to say Y here; if you
1729 say Y here even though you have a coprocessor, the coprocessor will
1730 be used nevertheless. (This behavior can be changed with the kernel
1731 command line option "no387", which comes handy if your coprocessor
1732 is broken. Try "man bootparam" or see the documentation of your boot
1733 loader (lilo or loadlin) about how to pass options to the kernel at
1734 boot time.) This means that it is a good idea to say Y here if you
1735 intend to use this kernel on different machines.
1737 More information about the internals of the Linux math coprocessor
1738 emulation can be found in <file:arch/x86/math-emu/README>.
1740 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1741 kernel, it won't hurt.
1745 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1747 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1748 the Memory Type Range Registers (MTRRs) may be used to control
1749 processor access to memory ranges. This is most useful if you have
1750 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1751 allows bus write transfers to be combined into a larger transfer
1752 before bursting over the PCI/AGP bus. This can increase performance
1753 of image write operations 2.5 times or more. Saying Y here creates a
1754 /proc/mtrr file which may be used to manipulate your processor's
1755 MTRRs. Typically the X server should use this.
1757 This code has a reasonably generic interface so that similar
1758 control registers on other processors can be easily supported
1761 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1762 Registers (ARRs) which provide a similar functionality to MTRRs. For
1763 these, the ARRs are used to emulate the MTRRs.
1764 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1765 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1766 write-combining. All of these processors are supported by this code
1767 and it makes sense to say Y here if you have one of them.
1769 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1770 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1771 can lead to all sorts of problems, so it's good to say Y here.
1773 You can safely say Y even if your machine doesn't have MTRRs, you'll
1774 just add about 9 KB to your kernel.
1776 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1778 config MTRR_SANITIZER
1780 prompt "MTRR cleanup support"
1783 Convert MTRR layout from continuous to discrete, so X drivers can
1784 add writeback entries.
1786 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1787 The largest mtrr entry size for a continuous block can be set with
1792 config MTRR_SANITIZER_ENABLE_DEFAULT
1793 int "MTRR cleanup enable value (0-1)"
1796 depends on MTRR_SANITIZER
1798 Enable mtrr cleanup default value
1800 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1801 int "MTRR cleanup spare reg num (0-7)"
1804 depends on MTRR_SANITIZER
1806 mtrr cleanup spare entries default, it can be changed via
1807 mtrr_spare_reg_nr=N on the kernel command line.
1811 prompt "x86 PAT support" if EXPERT
1814 Use PAT attributes to setup page level cache control.
1816 PATs are the modern equivalents of MTRRs and are much more
1817 flexible than MTRRs.
1819 Say N here if you see bootup problems (boot crash, boot hang,
1820 spontaneous reboots) or a non-working video driver.
1824 config ARCH_USES_PG_UNCACHED
1830 prompt "User Mode Instruction Prevention" if EXPERT
1832 User Mode Instruction Prevention (UMIP) is a security feature in
1833 some x86 processors. If enabled, a general protection fault is
1834 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1835 executed in user mode. These instructions unnecessarily expose
1836 information about the hardware state.
1838 The vast majority of applications do not use these instructions.
1839 For the very few that do, software emulation is provided in
1840 specific cases in protected and virtual-8086 modes. Emulated
1844 # GCC >= 9 and binutils >= 2.29
1845 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1847 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1848 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1849 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1850 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1853 config X86_KERNEL_IBT
1854 prompt "Indirect Branch Tracking"
1856 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1857 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1858 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1861 Build the kernel with support for Indirect Branch Tracking, a
1862 hardware support course-grain forward-edge Control Flow Integrity
1863 protection. It enforces that all indirect calls must land on
1864 an ENDBR instruction, as such, the compiler will instrument the
1865 code with them to make this happen.
1867 In addition to building the kernel with IBT, seal all functions that
1868 are not indirect call targets, avoiding them ever becoming one.
1870 This requires LTO like objtool runs and will slow down the build. It
1871 does significantly reduce the number of ENDBR instructions in the
1874 config X86_INTEL_MEMORY_PROTECTION_KEYS
1875 prompt "Memory Protection Keys"
1877 # Note: only available in 64-bit mode
1878 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1879 select ARCH_USES_HIGH_VMA_FLAGS
1880 select ARCH_HAS_PKEYS
1882 Memory Protection Keys provides a mechanism for enforcing
1883 page-based protections, but without requiring modification of the
1884 page tables when an application changes protection domains.
1886 For details, see Documentation/core-api/protection-keys.rst
1891 prompt "TSX enable mode"
1892 depends on CPU_SUP_INTEL
1893 default X86_INTEL_TSX_MODE_OFF
1895 Intel's TSX (Transactional Synchronization Extensions) feature
1896 allows to optimize locking protocols through lock elision which
1897 can lead to a noticeable performance boost.
1899 On the other hand it has been shown that TSX can be exploited
1900 to form side channel attacks (e.g. TAA) and chances are there
1901 will be more of those attacks discovered in the future.
1903 Therefore TSX is not enabled by default (aka tsx=off). An admin
1904 might override this decision by tsx=on the command line parameter.
1905 Even with TSX enabled, the kernel will attempt to enable the best
1906 possible TAA mitigation setting depending on the microcode available
1907 for the particular machine.
1909 This option allows to set the default tsx mode between tsx=on, =off
1910 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1913 Say off if not sure, auto if TSX is in use but it should be used on safe
1914 platforms or on if TSX is in use and the security aspect of tsx is not
1917 config X86_INTEL_TSX_MODE_OFF
1920 TSX is disabled if possible - equals to tsx=off command line parameter.
1922 config X86_INTEL_TSX_MODE_ON
1925 TSX is always enabled on TSX capable HW - equals the tsx=on command
1928 config X86_INTEL_TSX_MODE_AUTO
1931 TSX is enabled on TSX capable HW that is believed to be safe against
1932 side channel attacks- equals the tsx=auto command line parameter.
1936 bool "Software Guard eXtensions (SGX)"
1937 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1939 depends on CRYPTO_SHA256=y
1941 select NUMA_KEEP_MEMINFO if NUMA
1944 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1945 that can be used by applications to set aside private regions of code
1946 and data, referred to as enclaves. An enclave's private memory can
1947 only be accessed by code running within the enclave. Accesses from
1948 outside the enclave, including other enclaves, are disallowed by
1954 bool "EFI runtime service support"
1957 select EFI_RUNTIME_WRAPPERS
1958 select ARCH_USE_MEMREMAP_PROT
1960 This enables the kernel to use EFI runtime services that are
1961 available (such as the EFI variable services).
1963 This option is only useful on systems that have EFI firmware.
1964 In addition, you should use the latest ELILO loader available
1965 at <http://elilo.sourceforge.net> in order to take advantage
1966 of EFI runtime services. However, even with this option, the
1967 resultant kernel should continue to boot on existing non-EFI
1971 bool "EFI stub support"
1975 This kernel feature allows a bzImage to be loaded directly
1976 by EFI firmware without the use of a bootloader.
1978 See Documentation/admin-guide/efi-stub.rst for more information.
1980 config EFI_HANDOVER_PROTOCOL
1981 bool "EFI handover protocol (DEPRECATED)"
1985 Select this in order to include support for the deprecated EFI
1986 handover protocol, which defines alternative entry points into the
1987 EFI stub. This is a practice that has no basis in the UEFI
1988 specification, and requires a priori knowledge on the part of the
1989 bootloader about Linux/x86 specific ways of passing the command line
1990 and initrd, and where in memory those assets may be loaded.
1992 If in doubt, say Y. Even though the corresponding support is not
1993 present in upstream GRUB or other bootloaders, most distros build
1994 GRUB with numerous downstream patches applied, and may rely on the
1995 handover protocol as as result.
1998 bool "EFI mixed-mode support"
1999 depends on EFI_STUB && X86_64
2001 Enabling this feature allows a 64-bit kernel to be booted
2002 on a 32-bit firmware, provided that your CPU supports 64-bit
2005 Note that it is not possible to boot a mixed-mode enabled
2006 kernel via the EFI boot stub - a bootloader that supports
2007 the EFI handover protocol must be used.
2011 config EFI_FAKE_MEMMAP
2012 bool "Enable EFI fake memory map"
2015 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2016 this parameter, you can add arbitrary attribute to specific memory
2017 range by updating original (firmware provided) EFI memmap. This is
2018 useful for debugging of EFI memmap related feature, e.g., Address
2019 Range Mirroring feature.
2021 config EFI_MAX_FAKE_MEM
2022 int "maximum allowable number of ranges in efi_fake_mem boot option"
2023 depends on EFI_FAKE_MEMMAP
2027 Maximum allowable number of ranges in efi_fake_mem boot option.
2028 Ranges can be set up to this value using comma-separated list.
2029 The default value is 8.
2031 config EFI_RUNTIME_MAP
2032 bool "Export EFI runtime maps to sysfs" if EXPERT
2036 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2037 That memory map is required by the 2nd kernel to set up EFI virtual
2038 mappings after kexec, but can also be used for debugging purposes.
2040 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2042 source "kernel/Kconfig.hz"
2045 bool "kexec system call"
2048 kexec is a system call that implements the ability to shutdown your
2049 current kernel, and to start another kernel. It is like a reboot
2050 but it is independent of the system firmware. And like a reboot
2051 you can start any kernel with it, not just Linux.
2053 The name comes from the similarity to the exec system call.
2055 It is an ongoing process to be certain the hardware in a machine
2056 is properly shutdown, so do not be surprised if this code does not
2057 initially work for you. As of this writing the exact hardware
2058 interface is strongly in flux, so no good recommendation can be
2062 bool "kexec file based system call"
2064 select HAVE_IMA_KEXEC if IMA
2067 depends on CRYPTO_SHA256=y
2069 This is new version of kexec system call. This system call is
2070 file based and takes file descriptors as system call argument
2071 for kernel and initramfs as opposed to list of segments as
2072 accepted by previous system call.
2074 config ARCH_HAS_KEXEC_PURGATORY
2078 bool "Verify kernel signature during kexec_file_load() syscall"
2079 depends on KEXEC_FILE
2082 This option makes the kexec_file_load() syscall check for a valid
2083 signature of the kernel image. The image can still be loaded without
2084 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2085 there's a signature that we can check, then it must be valid.
2087 In addition to this option, you need to enable signature
2088 verification for the corresponding kernel image type being
2089 loaded in order for this to work.
2091 config KEXEC_SIG_FORCE
2092 bool "Require a valid signature in kexec_file_load() syscall"
2093 depends on KEXEC_SIG
2095 This option makes kernel signature verification mandatory for
2096 the kexec_file_load() syscall.
2098 config KEXEC_BZIMAGE_VERIFY_SIG
2099 bool "Enable bzImage signature verification support"
2100 depends on KEXEC_SIG
2101 depends on SIGNED_PE_FILE_VERIFICATION
2102 select SYSTEM_TRUSTED_KEYRING
2104 Enable bzImage signature verification support.
2107 bool "kernel crash dumps"
2108 depends on X86_64 || (X86_32 && HIGHMEM)
2110 Generate crash dump after being started by kexec.
2111 This should be normally only set in special crash dump kernels
2112 which are loaded in the main kernel with kexec-tools into
2113 a specially reserved region and then later executed after
2114 a crash by kdump/kexec. The crash dump kernel must be compiled
2115 to a memory address not used by the main kernel or BIOS using
2116 PHYSICAL_START, or it must be built as a relocatable image
2117 (CONFIG_RELOCATABLE=y).
2118 For more details see Documentation/admin-guide/kdump/kdump.rst
2122 depends on KEXEC && HIBERNATION
2124 Jump between original kernel and kexeced kernel and invoke
2125 code in physical address mode via KEXEC
2127 config PHYSICAL_START
2128 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2131 This gives the physical address where the kernel is loaded.
2133 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2134 bzImage will decompress itself to above physical address and
2135 run from there. Otherwise, bzImage will run from the address where
2136 it has been loaded by the boot loader and will ignore above physical
2139 In normal kdump cases one does not have to set/change this option
2140 as now bzImage can be compiled as a completely relocatable image
2141 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2142 address. This option is mainly useful for the folks who don't want
2143 to use a bzImage for capturing the crash dump and want to use a
2144 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2145 to be specifically compiled to run from a specific memory area
2146 (normally a reserved region) and this option comes handy.
2148 So if you are using bzImage for capturing the crash dump,
2149 leave the value here unchanged to 0x1000000 and set
2150 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2151 for capturing the crash dump change this value to start of
2152 the reserved region. In other words, it can be set based on
2153 the "X" value as specified in the "crashkernel=YM@XM"
2154 command line boot parameter passed to the panic-ed
2155 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2156 for more details about crash dumps.
2158 Usage of bzImage for capturing the crash dump is recommended as
2159 one does not have to build two kernels. Same kernel can be used
2160 as production kernel and capture kernel. Above option should have
2161 gone away after relocatable bzImage support is introduced. But it
2162 is present because there are users out there who continue to use
2163 vmlinux for dump capture. This option should go away down the
2166 Don't change this unless you know what you are doing.
2169 bool "Build a relocatable kernel"
2172 This builds a kernel image that retains relocation information
2173 so it can be loaded someplace besides the default 1MB.
2174 The relocations tend to make the kernel binary about 10% larger,
2175 but are discarded at runtime.
2177 One use is for the kexec on panic case where the recovery kernel
2178 must live at a different physical address than the primary
2181 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2182 it has been loaded at and the compile time physical address
2183 (CONFIG_PHYSICAL_START) is used as the minimum location.
2185 config RANDOMIZE_BASE
2186 bool "Randomize the address of the kernel image (KASLR)"
2187 depends on RELOCATABLE
2190 In support of Kernel Address Space Layout Randomization (KASLR),
2191 this randomizes the physical address at which the kernel image
2192 is decompressed and the virtual address where the kernel
2193 image is mapped, as a security feature that deters exploit
2194 attempts relying on knowledge of the location of kernel
2197 On 64-bit, the kernel physical and virtual addresses are
2198 randomized separately. The physical address will be anywhere
2199 between 16MB and the top of physical memory (up to 64TB). The
2200 virtual address will be randomized from 16MB up to 1GB (9 bits
2201 of entropy). Note that this also reduces the memory space
2202 available to kernel modules from 1.5GB to 1GB.
2204 On 32-bit, the kernel physical and virtual addresses are
2205 randomized together. They will be randomized from 16MB up to
2206 512MB (8 bits of entropy).
2208 Entropy is generated using the RDRAND instruction if it is
2209 supported. If RDTSC is supported, its value is mixed into
2210 the entropy pool as well. If neither RDRAND nor RDTSC are
2211 supported, then entropy is read from the i8254 timer. The
2212 usable entropy is limited by the kernel being built using
2213 2GB addressing, and that PHYSICAL_ALIGN must be at a
2214 minimum of 2MB. As a result, only 10 bits of entropy are
2215 theoretically possible, but the implementations are further
2216 limited due to memory layouts.
2220 # Relocation on x86 needs some additional build support
2221 config X86_NEED_RELOCS
2223 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2225 config PHYSICAL_ALIGN
2226 hex "Alignment value to which kernel should be aligned"
2228 range 0x2000 0x1000000 if X86_32
2229 range 0x200000 0x1000000 if X86_64
2231 This value puts the alignment restrictions on physical address
2232 where kernel is loaded and run from. Kernel is compiled for an
2233 address which meets above alignment restriction.
2235 If bootloader loads the kernel at a non-aligned address and
2236 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2237 address aligned to above value and run from there.
2239 If bootloader loads the kernel at a non-aligned address and
2240 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2241 load address and decompress itself to the address it has been
2242 compiled for and run from there. The address for which kernel is
2243 compiled already meets above alignment restrictions. Hence the
2244 end result is that kernel runs from a physical address meeting
2245 above alignment restrictions.
2247 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2248 this value must be a multiple of 0x200000.
2250 Don't change this unless you know what you are doing.
2252 config DYNAMIC_MEMORY_LAYOUT
2255 This option makes base addresses of vmalloc and vmemmap as well as
2256 __PAGE_OFFSET movable during boot.
2258 config RANDOMIZE_MEMORY
2259 bool "Randomize the kernel memory sections"
2261 depends on RANDOMIZE_BASE
2262 select DYNAMIC_MEMORY_LAYOUT
2263 default RANDOMIZE_BASE
2265 Randomizes the base virtual address of kernel memory sections
2266 (physical memory mapping, vmalloc & vmemmap). This security feature
2267 makes exploits relying on predictable memory locations less reliable.
2269 The order of allocations remains unchanged. Entropy is generated in
2270 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2271 configuration have in average 30,000 different possible virtual
2272 addresses for each memory section.
2276 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2277 hex "Physical memory mapping padding" if EXPERT
2278 depends on RANDOMIZE_MEMORY
2279 default "0xa" if MEMORY_HOTPLUG
2281 range 0x1 0x40 if MEMORY_HOTPLUG
2284 Define the padding in terabytes added to the existing physical
2285 memory size during kernel memory randomization. It is useful
2286 for memory hotplug support but reduces the entropy available for
2287 address randomization.
2289 If unsure, leave at the default value.
2295 config BOOTPARAM_HOTPLUG_CPU0
2296 bool "Set default setting of cpu0_hotpluggable"
2297 depends on HOTPLUG_CPU
2299 Set whether default state of cpu0_hotpluggable is on or off.
2301 Say Y here to enable CPU0 hotplug by default. If this switch
2302 is turned on, there is no need to give cpu0_hotplug kernel
2303 parameter and the CPU0 hotplug feature is enabled by default.
2305 Please note: there are two known CPU0 dependencies if you want
2306 to enable the CPU0 hotplug feature either by this switch or by
2307 cpu0_hotplug kernel parameter.
2309 First, resume from hibernate or suspend always starts from CPU0.
2310 So hibernate and suspend are prevented if CPU0 is offline.
2312 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2313 offline if any interrupt can not migrate out of CPU0. There may
2314 be other CPU0 dependencies.
2316 Please make sure the dependencies are under your control before
2317 you enable this feature.
2319 Say N if you don't want to enable CPU0 hotplug feature by default.
2320 You still can enable the CPU0 hotplug feature at boot by kernel
2321 parameter cpu0_hotplug.
2323 config DEBUG_HOTPLUG_CPU0
2325 prompt "Debug CPU0 hotplug"
2326 depends on HOTPLUG_CPU
2328 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2329 soon as possible and boots up userspace with CPU0 offlined. User
2330 can online CPU0 back after boot time.
2332 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2333 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2334 compilation or giving cpu0_hotplug kernel parameter at boot.
2340 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2341 depends on COMPAT_32
2343 Certain buggy versions of glibc will crash if they are
2344 presented with a 32-bit vDSO that is not mapped at the address
2345 indicated in its segment table.
2347 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2348 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2349 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2350 the only released version with the bug, but OpenSUSE 9
2351 contains a buggy "glibc 2.3.2".
2353 The symptom of the bug is that everything crashes on startup, saying:
2354 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2356 Saying Y here changes the default value of the vdso32 boot
2357 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2358 This works around the glibc bug but hurts performance.
2360 If unsure, say N: if you are compiling your own kernel, you
2361 are unlikely to be using a buggy version of glibc.
2364 prompt "vsyscall table for legacy applications"
2366 default LEGACY_VSYSCALL_XONLY
2368 Legacy user code that does not know how to find the vDSO expects
2369 to be able to issue three syscalls by calling fixed addresses in
2370 kernel space. Since this location is not randomized with ASLR,
2371 it can be used to assist security vulnerability exploitation.
2373 This setting can be changed at boot time via the kernel command
2374 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2375 is deprecated and can only be enabled using the kernel command
2378 On a system with recent enough glibc (2.14 or newer) and no
2379 static binaries, you can say None without a performance penalty
2380 to improve security.
2382 If unsure, select "Emulate execution only".
2384 config LEGACY_VSYSCALL_XONLY
2385 bool "Emulate execution only"
2387 The kernel traps and emulates calls into the fixed vsyscall
2388 address mapping and does not allow reads. This
2389 configuration is recommended when userspace might use the
2390 legacy vsyscall area but support for legacy binary
2391 instrumentation of legacy code is not needed. It mitigates
2392 certain uses of the vsyscall area as an ASLR-bypassing
2395 config LEGACY_VSYSCALL_NONE
2398 There will be no vsyscall mapping at all. This will
2399 eliminate any risk of ASLR bypass due to the vsyscall
2400 fixed address mapping. Attempts to use the vsyscalls
2401 will be reported to dmesg, so that either old or
2402 malicious userspace programs can be identified.
2407 bool "Built-in kernel command line"
2409 Allow for specifying boot arguments to the kernel at
2410 build time. On some systems (e.g. embedded ones), it is
2411 necessary or convenient to provide some or all of the
2412 kernel boot arguments with the kernel itself (that is,
2413 to not rely on the boot loader to provide them.)
2415 To compile command line arguments into the kernel,
2416 set this option to 'Y', then fill in the
2417 boot arguments in CONFIG_CMDLINE.
2419 Systems with fully functional boot loaders (i.e. non-embedded)
2420 should leave this option set to 'N'.
2423 string "Built-in kernel command string"
2424 depends on CMDLINE_BOOL
2427 Enter arguments here that should be compiled into the kernel
2428 image and used at boot time. If the boot loader provides a
2429 command line at boot time, it is appended to this string to
2430 form the full kernel command line, when the system boots.
2432 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2433 change this behavior.
2435 In most cases, the command line (whether built-in or provided
2436 by the boot loader) should specify the device for the root
2439 config CMDLINE_OVERRIDE
2440 bool "Built-in command line overrides boot loader arguments"
2441 depends on CMDLINE_BOOL && CMDLINE != ""
2443 Set this option to 'Y' to have the kernel ignore the boot loader
2444 command line, and use ONLY the built-in command line.
2446 This is used to work around broken boot loaders. This should
2447 be set to 'N' under normal conditions.
2449 config MODIFY_LDT_SYSCALL
2450 bool "Enable the LDT (local descriptor table)" if EXPERT
2453 Linux can allow user programs to install a per-process x86
2454 Local Descriptor Table (LDT) using the modify_ldt(2) system
2455 call. This is required to run 16-bit or segmented code such as
2456 DOSEMU or some Wine programs. It is also used by some very old
2457 threading libraries.
2459 Enabling this feature adds a small amount of overhead to
2460 context switches and increases the low-level kernel attack
2461 surface. Disabling it removes the modify_ldt(2) system call.
2463 Saying 'N' here may make sense for embedded or server kernels.
2465 config STRICT_SIGALTSTACK_SIZE
2466 bool "Enforce strict size checking for sigaltstack"
2467 depends on DYNAMIC_SIGFRAME
2469 For historical reasons MINSIGSTKSZ is a constant which became
2470 already too small with AVX512 support. Add a mechanism to
2471 enforce strict checking of the sigaltstack size against the
2472 real size of the FPU frame. This option enables the check
2473 by default. It can also be controlled via the kernel command
2474 line option 'strict_sas_size' independent of this config
2475 switch. Enabling it might break existing applications which
2476 allocate a too small sigaltstack but 'work' because they
2477 never get a signal delivered.
2479 Say 'N' unless you want to really enforce this check.
2481 source "kernel/livepatch/Kconfig"
2486 def_bool $(cc-option,-mharden-sls=all)
2488 config CC_HAS_RETURN_THUNK
2489 def_bool $(cc-option,-mfunction-return=thunk-extern)
2491 config CC_HAS_ENTRY_PADDING
2492 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2494 config FUNCTION_PADDING_CFI
2496 default 59 if FUNCTION_ALIGNMENT_64B
2497 default 27 if FUNCTION_ALIGNMENT_32B
2498 default 11 if FUNCTION_ALIGNMENT_16B
2499 default 3 if FUNCTION_ALIGNMENT_8B
2502 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2503 # except Kconfig can't do arithmetic :/
2504 config FUNCTION_PADDING_BYTES
2506 default FUNCTION_PADDING_CFI if CFI_CLANG
2507 default FUNCTION_ALIGNMENT
2511 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2512 select FUNCTION_ALIGNMENT_16B
2516 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2519 config HAVE_CALL_THUNKS
2521 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2527 config PREFIX_SYMBOLS
2529 depends on CALL_PADDING && !CFI_CLANG
2531 menuconfig SPECULATION_MITIGATIONS
2532 bool "Mitigations for speculative execution vulnerabilities"
2535 Say Y here to enable options which enable mitigations for
2536 speculative execution hardware vulnerabilities.
2538 If you say N, all mitigations will be disabled. You really
2539 should know what you are doing to say so.
2541 if SPECULATION_MITIGATIONS
2543 config PAGE_TABLE_ISOLATION
2544 bool "Remove the kernel mapping in user mode"
2546 depends on (X86_64 || X86_PAE)
2548 This feature reduces the number of hardware side channels by
2549 ensuring that the majority of kernel addresses are not mapped
2552 See Documentation/arch/x86/pti.rst for more details.
2555 bool "Avoid speculative indirect branches in kernel"
2556 select OBJTOOL if HAVE_OBJTOOL
2559 Compile kernel with the retpoline compiler options to guard against
2560 kernel-to-user data leaks by avoiding speculative indirect
2561 branches. Requires a compiler with -mindirect-branch=thunk-extern
2562 support for full protection. The kernel may run slower.
2565 bool "Enable return-thunks"
2566 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2567 select OBJTOOL if HAVE_OBJTOOL
2570 Compile the kernel with the return-thunks compiler option to guard
2571 against kernel-to-user data leaks by avoiding return speculation.
2572 Requires a compiler with -mfunction-return=thunk-extern
2573 support for full protection. The kernel may run slower.
2575 config CPU_UNRET_ENTRY
2576 bool "Enable UNRET on kernel entry"
2577 depends on CPU_SUP_AMD && RETHUNK && X86_64
2580 Compile the kernel with support for the retbleed=unret mitigation.
2582 config CALL_DEPTH_TRACKING
2583 bool "Mitigate RSB underflow with call depth tracking"
2584 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2585 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2589 Compile the kernel with call depth tracking to mitigate the Intel
2590 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2591 mitigation is off by default and needs to be enabled on the
2592 kernel command line via the retbleed=stuff option. For
2593 non-affected systems the overhead of this option is marginal as
2594 the call depth tracking is using run-time generated call thunks
2595 in a compiler generated padding area and call patching. This
2596 increases text size by ~5%. For non affected systems this space
2597 is unused. On affected SKL systems this results in a significant
2598 performance gain over the IBRS mitigation.
2600 config CALL_THUNKS_DEBUG
2601 bool "Enable call thunks and call depth tracking debugging"
2602 depends on CALL_DEPTH_TRACKING
2603 select FUNCTION_ALIGNMENT_32B
2606 Enable call/ret counters for imbalance detection and build in
2607 a noisy dmesg about callthunks generation and call patching for
2608 trouble shooting. The debug prints need to be enabled on the
2609 kernel command line with 'debug-callthunks'.
2610 Only enable this when you are debugging call thunks as this
2611 creates a noticeable runtime overhead. If unsure say N.
2613 config CPU_IBPB_ENTRY
2614 bool "Enable IBPB on kernel entry"
2615 depends on CPU_SUP_AMD && X86_64
2618 Compile the kernel with support for the retbleed=ibpb mitigation.
2620 config CPU_IBRS_ENTRY
2621 bool "Enable IBRS on kernel entry"
2622 depends on CPU_SUP_INTEL && X86_64
2625 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2626 This mitigates both spectre_v2 and retbleed at great cost to
2630 bool "Mitigate Straight-Line-Speculation"
2631 depends on CC_HAS_SLS && X86_64
2632 select OBJTOOL if HAVE_OBJTOOL
2635 Compile the kernel with straight-line-speculation options to guard
2636 against straight line speculation. The kernel image might be slightly
2641 config ARCH_HAS_ADD_PAGES
2643 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2645 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2648 menu "Power management and ACPI options"
2650 config ARCH_HIBERNATION_HEADER
2652 depends on HIBERNATION
2654 source "kernel/power/Kconfig"
2656 source "drivers/acpi/Kconfig"
2663 tristate "APM (Advanced Power Management) BIOS support"
2664 depends on X86_32 && PM_SLEEP
2666 APM is a BIOS specification for saving power using several different
2667 techniques. This is mostly useful for battery powered laptops with
2668 APM compliant BIOSes. If you say Y here, the system time will be
2669 reset after a RESUME operation, the /proc/apm device will provide
2670 battery status information, and user-space programs will receive
2671 notification of APM "events" (e.g. battery status change).
2673 If you select "Y" here, you can disable actual use of the APM
2674 BIOS by passing the "apm=off" option to the kernel at boot time.
2676 Note that the APM support is almost completely disabled for
2677 machines with more than one CPU.
2679 In order to use APM, you will need supporting software. For location
2680 and more information, read <file:Documentation/power/apm-acpi.rst>
2681 and the Battery Powered Linux mini-HOWTO, available from
2682 <http://www.tldp.org/docs.html#howto>.
2684 This driver does not spin down disk drives (see the hdparm(8)
2685 manpage ("man 8 hdparm") for that), and it doesn't turn off
2686 VESA-compliant "green" monitors.
2688 This driver does not support the TI 4000M TravelMate and the ACER
2689 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2690 desktop machines also don't have compliant BIOSes, and this driver
2691 may cause those machines to panic during the boot phase.
2693 Generally, if you don't have a battery in your machine, there isn't
2694 much point in using this driver and you should say N. If you get
2695 random kernel OOPSes or reboots that don't seem to be related to
2696 anything, try disabling/enabling this option (or disabling/enabling
2699 Some other things you should try when experiencing seemingly random,
2702 1) make sure that you have enough swap space and that it is
2704 2) pass the "idle=poll" option to the kernel
2705 3) switch on floating point emulation in the kernel and pass
2706 the "no387" option to the kernel
2707 4) pass the "floppy=nodma" option to the kernel
2708 5) pass the "mem=4M" option to the kernel (thereby disabling
2709 all but the first 4 MB of RAM)
2710 6) make sure that the CPU is not over clocked.
2711 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2712 8) disable the cache from your BIOS settings
2713 9) install a fan for the video card or exchange video RAM
2714 10) install a better fan for the CPU
2715 11) exchange RAM chips
2716 12) exchange the motherboard.
2718 To compile this driver as a module, choose M here: the
2719 module will be called apm.
2723 config APM_IGNORE_USER_SUSPEND
2724 bool "Ignore USER SUSPEND"
2726 This option will ignore USER SUSPEND requests. On machines with a
2727 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2728 series notebooks, it is necessary to say Y because of a BIOS bug.
2730 config APM_DO_ENABLE
2731 bool "Enable PM at boot time"
2733 Enable APM features at boot time. From page 36 of the APM BIOS
2734 specification: "When disabled, the APM BIOS does not automatically
2735 power manage devices, enter the Standby State, enter the Suspend
2736 State, or take power saving steps in response to CPU Idle calls."
2737 This driver will make CPU Idle calls when Linux is idle (unless this
2738 feature is turned off -- see "Do CPU IDLE calls", below). This
2739 should always save battery power, but more complicated APM features
2740 will be dependent on your BIOS implementation. You may need to turn
2741 this option off if your computer hangs at boot time when using APM
2742 support, or if it beeps continuously instead of suspending. Turn
2743 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2744 T400CDT. This is off by default since most machines do fine without
2749 bool "Make CPU Idle calls when idle"
2751 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2752 On some machines, this can activate improved power savings, such as
2753 a slowed CPU clock rate, when the machine is idle. These idle calls
2754 are made after the idle loop has run for some length of time (e.g.,
2755 333 mS). On some machines, this will cause a hang at boot time or
2756 whenever the CPU becomes idle. (On machines with more than one CPU,
2757 this option does nothing.)
2759 config APM_DISPLAY_BLANK
2760 bool "Enable console blanking using APM"
2762 Enable console blanking using the APM. Some laptops can use this to
2763 turn off the LCD backlight when the screen blanker of the Linux
2764 virtual console blanks the screen. Note that this is only used by
2765 the virtual console screen blanker, and won't turn off the backlight
2766 when using the X Window system. This also doesn't have anything to
2767 do with your VESA-compliant power-saving monitor. Further, this
2768 option doesn't work for all laptops -- it might not turn off your
2769 backlight at all, or it might print a lot of errors to the console,
2770 especially if you are using gpm.
2772 config APM_ALLOW_INTS
2773 bool "Allow interrupts during APM BIOS calls"
2775 Normally we disable external interrupts while we are making calls to
2776 the APM BIOS as a measure to lessen the effects of a badly behaving
2777 BIOS implementation. The BIOS should reenable interrupts if it
2778 needs to. Unfortunately, some BIOSes do not -- especially those in
2779 many of the newer IBM Thinkpads. If you experience hangs when you
2780 suspend, try setting this to Y. Otherwise, say N.
2784 source "drivers/cpufreq/Kconfig"
2786 source "drivers/cpuidle/Kconfig"
2788 source "drivers/idle/Kconfig"
2792 menu "Bus options (PCI etc.)"
2795 prompt "PCI access mode"
2796 depends on X86_32 && PCI
2799 On PCI systems, the BIOS can be used to detect the PCI devices and
2800 determine their configuration. However, some old PCI motherboards
2801 have BIOS bugs and may crash if this is done. Also, some embedded
2802 PCI-based systems don't have any BIOS at all. Linux can also try to
2803 detect the PCI hardware directly without using the BIOS.
2805 With this option, you can specify how Linux should detect the
2806 PCI devices. If you choose "BIOS", the BIOS will be used,
2807 if you choose "Direct", the BIOS won't be used, and if you
2808 choose "MMConfig", then PCI Express MMCONFIG will be used.
2809 If you choose "Any", the kernel will try MMCONFIG, then the
2810 direct access method and falls back to the BIOS if that doesn't
2811 work. If unsure, go with the default, which is "Any".
2816 config PCI_GOMMCONFIG
2833 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2835 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2838 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2841 bool "Support mmconfig PCI config space access" if X86_64
2843 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2844 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2848 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2852 depends on PCI && XEN
2854 config MMCONF_FAM10H
2856 depends on X86_64 && PCI_MMCONFIG && ACPI
2858 config PCI_CNB20LE_QUIRK
2859 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2862 Read the PCI windows out of the CNB20LE host bridge. This allows
2863 PCI hotplug to work on systems with the CNB20LE chipset which do
2866 There's no public spec for this chipset, and this functionality
2867 is known to be incomplete.
2869 You should say N unless you know you need this.
2872 bool "ISA bus support on modern systems" if EXPERT
2874 Expose ISA bus device drivers and options available for selection and
2875 configuration. Enable this option if your target machine has an ISA
2876 bus. ISA is an older system, displaced by PCI and newer bus
2877 architectures -- if your target machine is modern, it probably does
2878 not have an ISA bus.
2882 # x86_64 have no ISA slots, but can have ISA-style DMA.
2884 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2887 Enables ISA-style DMA support for devices requiring such controllers.
2895 Find out whether you have ISA slots on your motherboard. ISA is the
2896 name of a bus system, i.e. the way the CPU talks to the other stuff
2897 inside your box. Other bus systems are PCI, EISA, MicroChannel
2898 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2899 newer boards don't support it. If you have ISA, say Y, otherwise N.
2902 tristate "NatSemi SCx200 support"
2904 This provides basic support for National Semiconductor's
2905 (now AMD's) Geode processors. The driver probes for the
2906 PCI-IDs of several on-chip devices, so its a good dependency
2907 for other scx200_* drivers.
2909 If compiled as a module, the driver is named scx200.
2911 config SCx200HR_TIMER
2912 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2916 This driver provides a clocksource built upon the on-chip
2917 27MHz high-resolution timer. Its also a workaround for
2918 NSC Geode SC-1100's buggy TSC, which loses time when the
2919 processor goes idle (as is done by the scheduler). The
2920 other workaround is idle=poll boot option.
2923 bool "One Laptop Per Child support"
2931 Add support for detecting the unique features of the OLPC
2935 bool "OLPC XO-1 Power Management"
2936 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2938 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2941 bool "OLPC XO-1 Real Time Clock"
2942 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2944 Add support for the XO-1 real time clock, which can be used as a
2945 programmable wakeup source.
2948 bool "OLPC XO-1 SCI extras"
2949 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2953 Add support for SCI-based features of the OLPC XO-1 laptop:
2954 - EC-driven system wakeups
2958 - AC adapter status updates
2959 - Battery status updates
2961 config OLPC_XO15_SCI
2962 bool "OLPC XO-1.5 SCI extras"
2963 depends on OLPC && ACPI
2966 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2967 - EC-driven system wakeups
2968 - AC adapter status updates
2969 - Battery status updates
2972 bool "PCEngines ALIX System Support (LED setup)"
2975 This option enables system support for the PCEngines ALIX.
2976 At present this just sets up LEDs for GPIO control on
2977 ALIX2/3/6 boards. However, other system specific setup should
2980 Note: You must still enable the drivers for GPIO and LED support
2981 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2983 Note: You have to set alix.force=1 for boards with Award BIOS.
2986 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2989 This option enables system support for the Soekris Engineering net5501.
2992 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2996 This option enables system support for the Traverse Technologies GEOS.
2999 bool "Technologic Systems TS-5500 platform support"
3001 select CHECK_SIGNATURE
3005 This option enables system support for the Technologic Systems TS-5500.
3011 depends on CPU_SUP_AMD && PCI
3015 menu "Binary Emulations"
3017 config IA32_EMULATION
3018 bool "IA32 Emulation"
3020 select ARCH_WANT_OLD_COMPAT_IPC
3022 select COMPAT_OLD_SIGACTION
3024 Include code to run legacy 32-bit programs under a
3025 64-bit kernel. You should likely turn this on, unless you're
3026 100% sure that you don't have any 32-bit programs left.
3029 bool "x32 ABI for 64-bit mode"
3031 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3032 # compressed debug sections to x86_x32 properly:
3033 # https://github.com/ClangBuiltLinux/linux/issues/514
3034 # https://github.com/ClangBuiltLinux/linux/issues/1141
3035 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3037 Include code to run binaries for the x32 native 32-bit ABI
3038 for 64-bit processors. An x32 process gets access to the
3039 full 64-bit register file and wide data path while leaving
3040 pointers at 32 bits for smaller memory footprint.
3044 depends on IA32_EMULATION || X86_32
3046 select OLD_SIGSUSPEND3
3050 depends on IA32_EMULATION || X86_X32_ABI
3052 config COMPAT_FOR_U64_ALIGNMENT
3058 config HAVE_ATOMIC_IOMAP
3062 source "arch/x86/kvm/Kconfig"
3064 source "arch/x86/Kconfig.assembler"