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_SUPPORTS_PER_VMA_LOCK
31 select ARCH_USE_CMPXCHG_LOCKREF
32 select HAVE_ARCH_SOFT_DIRTY
33 select MODULES_USE_ELF_RELA
34 select NEED_DMA_MAP_STATE
36 select ARCH_HAS_ELFCORE_COMPAT
39 config FORCE_DYNAMIC_FTRACE
42 depends on FUNCTION_TRACER
45 We keep the static function tracing (!DYNAMIC_FTRACE) around
46 in order to test the non static function tracing in the
47 generic code, as other architectures still use it. But we
48 only need to keep it around for x86_64. No need to keep it
49 for x86_32. For x86_32, force DYNAMIC_FTRACE.
53 # ( Note that options that are marked 'if X86_64' could in principle be
54 # ported to 32-bit as well. )
59 # Note: keep this list sorted alphabetically
61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
63 select ARCH_32BIT_OFF_T if X86_32
64 select ARCH_CLOCKSOURCE_INIT
65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
72 select ARCH_HAS_CACHE_LINE_SIZE
73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
74 select ARCH_HAS_CPU_FINALIZE_INIT
75 select ARCH_HAS_CURRENT_STACK_POINTER
76 select ARCH_HAS_DEBUG_VIRTUAL
77 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
78 select ARCH_HAS_DEVMEM_IS_ALLOWED
79 select ARCH_HAS_EARLY_DEBUG if KGDB
80 select ARCH_HAS_ELF_RANDOMIZE
81 select ARCH_HAS_FAST_MULTIPLIER
82 select ARCH_HAS_FORTIFY_SOURCE
83 select ARCH_HAS_GCOV_PROFILE_ALL
84 select ARCH_HAS_KCOV if X86_64
85 select ARCH_HAS_MEM_ENCRYPT
86 select ARCH_HAS_MEMBARRIER_SYNC_CORE
87 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
88 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
89 select ARCH_HAS_PMEM_API if X86_64
90 select ARCH_HAS_PTE_DEVMAP if X86_64
91 select ARCH_HAS_PTE_SPECIAL
92 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
93 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
94 select ARCH_HAS_COPY_MC if X86_64
95 select ARCH_HAS_SET_MEMORY
96 select ARCH_HAS_SET_DIRECT_MAP
97 select ARCH_HAS_STRICT_KERNEL_RWX
98 select ARCH_HAS_STRICT_MODULE_RWX
99 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
100 select ARCH_HAS_SYSCALL_WRAPPER
101 select ARCH_HAS_UBSAN_SANITIZE_ALL
102 select ARCH_HAS_DEBUG_WX
103 select ARCH_HAS_ZONE_DMA_SET if EXPERT
104 select ARCH_HAVE_NMI_SAFE_CMPXCHG
105 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
106 select ARCH_MIGHT_HAVE_PC_PARPORT
107 select ARCH_MIGHT_HAVE_PC_SERIO
108 select ARCH_STACKWALK
109 select ARCH_SUPPORTS_ACPI
110 select ARCH_SUPPORTS_ATOMIC_RMW
111 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
112 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
113 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
114 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
115 select ARCH_SUPPORTS_CFI_CLANG if X86_64
116 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
117 select ARCH_SUPPORTS_LTO_CLANG
118 select ARCH_SUPPORTS_LTO_CLANG_THIN
119 select ARCH_USE_BUILTIN_BSWAP
120 select ARCH_USE_MEMTEST
121 select ARCH_USE_QUEUED_RWLOCKS
122 select ARCH_USE_QUEUED_SPINLOCKS
123 select ARCH_USE_SYM_ANNOTATIONS
124 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
125 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
126 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
127 select ARCH_WANTS_NO_INSTR
128 select ARCH_WANT_GENERAL_HUGETLB
129 select ARCH_WANT_HUGE_PMD_SHARE
130 select ARCH_WANT_LD_ORPHAN_WARN
131 select ARCH_WANT_OPTIMIZE_VMEMMAP if X86_64
132 select ARCH_WANTS_THP_SWAP if X86_64
133 select ARCH_HAS_PARANOID_L1D_FLUSH
134 select BUILDTIME_TABLE_SORT
136 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
137 select CLOCKSOURCE_WATCHDOG
138 # Word-size accesses may read uninitialized data past the trailing \0
139 # in strings and cause false KMSAN reports.
140 select DCACHE_WORD_ACCESS if !KMSAN
141 select DYNAMIC_SIGFRAME
142 select EDAC_ATOMIC_SCRUB
144 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
145 select GENERIC_CLOCKEVENTS_MIN_ADJUST
146 select GENERIC_CMOS_UPDATE
147 select GENERIC_CPU_AUTOPROBE
148 select GENERIC_CPU_VULNERABILITIES
149 select GENERIC_EARLY_IOREMAP
152 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
153 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
154 select GENERIC_IRQ_MIGRATION if SMP
155 select GENERIC_IRQ_PROBE
156 select GENERIC_IRQ_RESERVATION_MODE
157 select GENERIC_IRQ_SHOW
158 select GENERIC_PENDING_IRQ if SMP
159 select GENERIC_PTDUMP
160 select GENERIC_SMP_IDLE_THREAD
161 select GENERIC_TIME_VSYSCALL
162 select GENERIC_GETTIMEOFDAY
163 select GENERIC_VDSO_TIME_NS
164 select GUP_GET_PXX_LOW_HIGH if X86_PAE
165 select HARDIRQS_SW_RESEND
166 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
168 select HAVE_ACPI_APEI if ACPI
169 select HAVE_ACPI_APEI_NMI if ACPI
170 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
171 select HAVE_ARCH_AUDITSYSCALL
172 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
173 select HAVE_ARCH_HUGE_VMALLOC if X86_64
174 select HAVE_ARCH_JUMP_LABEL
175 select HAVE_ARCH_JUMP_LABEL_RELATIVE
176 select HAVE_ARCH_KASAN if X86_64
177 select HAVE_ARCH_KASAN_VMALLOC if X86_64
178 select HAVE_ARCH_KFENCE
179 select HAVE_ARCH_KMSAN if X86_64
180 select HAVE_ARCH_KGDB
181 select HAVE_ARCH_MMAP_RND_BITS if MMU
182 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
183 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
184 select HAVE_ARCH_PREL32_RELOCATIONS
185 select HAVE_ARCH_SECCOMP_FILTER
186 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
187 select HAVE_ARCH_STACKLEAK
188 select HAVE_ARCH_TRACEHOOK
189 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
190 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
191 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
192 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
193 select HAVE_ARCH_VMAP_STACK if X86_64
194 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
195 select HAVE_ARCH_WITHIN_STACK_FRAMES
196 select HAVE_ASM_MODVERSIONS
197 select HAVE_CMPXCHG_DOUBLE
198 select HAVE_CMPXCHG_LOCAL
199 select HAVE_CONTEXT_TRACKING_USER if X86_64
200 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
201 select HAVE_C_RECORDMCOUNT
202 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
203 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
204 select HAVE_BUILDTIME_MCOUNT_SORT
205 select HAVE_DEBUG_KMEMLEAK
206 select HAVE_DMA_CONTIGUOUS
207 select HAVE_DYNAMIC_FTRACE
208 select HAVE_DYNAMIC_FTRACE_WITH_REGS
209 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
210 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
211 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
212 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
214 select HAVE_EFFICIENT_UNALIGNED_ACCESS
216 select HAVE_EXIT_THREAD
218 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
219 select HAVE_FTRACE_MCOUNT_RECORD
220 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
221 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
222 select HAVE_FUNCTION_TRACER
223 select HAVE_GCC_PLUGINS
224 select HAVE_HW_BREAKPOINT
225 select HAVE_IOREMAP_PROT
226 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
227 select HAVE_IRQ_TIME_ACCOUNTING
228 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
229 select HAVE_KERNEL_BZIP2
230 select HAVE_KERNEL_GZIP
231 select HAVE_KERNEL_LZ4
232 select HAVE_KERNEL_LZMA
233 select HAVE_KERNEL_LZO
234 select HAVE_KERNEL_XZ
235 select HAVE_KERNEL_ZSTD
237 select HAVE_KPROBES_ON_FTRACE
238 select HAVE_FUNCTION_ERROR_INJECTION
239 select HAVE_KRETPROBES
242 select HAVE_LIVEPATCH if X86_64
243 select HAVE_MIXED_BREAKPOINTS_REGS
244 select HAVE_MOD_ARCH_SPECIFIC
247 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
249 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
250 select HAVE_OBJTOOL if X86_64
251 select HAVE_OPTPROBES
252 select HAVE_PCSPKR_PLATFORM
253 select HAVE_PERF_EVENTS
254 select HAVE_PERF_EVENTS_NMI
255 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
257 select HAVE_PERF_REGS
258 select HAVE_PERF_USER_STACK_DUMP
259 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
260 select MMU_GATHER_MERGE_VMAS
261 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
262 select HAVE_REGS_AND_STACK_ACCESS_API
263 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
264 select HAVE_FUNCTION_ARG_ACCESS_API
265 select HAVE_SETUP_PER_CPU_AREA
266 select HAVE_SOFTIRQ_ON_OWN_STACK
267 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
268 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
269 select HAVE_STATIC_CALL
270 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
271 select HAVE_PREEMPT_DYNAMIC_CALL
273 select HAVE_RUST if X86_64
274 select HAVE_SYSCALL_TRACEPOINTS
275 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
276 select HAVE_UNSTABLE_SCHED_CLOCK
277 select HAVE_USER_RETURN_NOTIFIER
278 select HAVE_GENERIC_VDSO
279 select HOTPLUG_PARALLEL if SMP && X86_64
280 select HOTPLUG_SMT if SMP
281 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
282 select IRQ_FORCED_THREADING
283 select LOCK_MM_AND_FIND_VMA
284 select NEED_PER_CPU_EMBED_FIRST_CHUNK
285 select NEED_PER_CPU_PAGE_FIRST_CHUNK
286 select NEED_SG_DMA_LENGTH
287 select PCI_DOMAINS if PCI
288 select PCI_LOCKLESS_CONFIG if PCI
291 select RTC_MC146818_LIB
293 select SYSCTL_EXCEPTION_TRACE
294 select THREAD_INFO_IN_TASK
295 select TRACE_IRQFLAGS_SUPPORT
296 select TRACE_IRQFLAGS_NMI_SUPPORT
297 select USER_STACKTRACE_SUPPORT
298 select HAVE_ARCH_KCSAN if X86_64
299 select PROC_PID_ARCH_STATUS if PROC_FS
300 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
301 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
302 select FUNCTION_ALIGNMENT_4B
303 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
304 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
306 config INSTRUCTION_DECODER
308 depends on KPROBES || PERF_EVENTS || UPROBES
312 default "elf32-i386" if X86_32
313 default "elf64-x86-64" if X86_64
315 config LOCKDEP_SUPPORT
318 config STACKTRACE_SUPPORT
324 config ARCH_MMAP_RND_BITS_MIN
328 config ARCH_MMAP_RND_BITS_MAX
332 config ARCH_MMAP_RND_COMPAT_BITS_MIN
335 config ARCH_MMAP_RND_COMPAT_BITS_MAX
341 config GENERIC_ISA_DMA
343 depends on ISA_DMA_API
347 default y if KMSAN || KASAN
352 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
354 config GENERIC_BUG_RELATIVE_POINTERS
357 config ARCH_MAY_HAVE_PC_FDC
359 depends on ISA_DMA_API
361 config GENERIC_CALIBRATE_DELAY
364 config ARCH_HAS_CPU_RELAX
367 config ARCH_HIBERNATION_POSSIBLE
370 config ARCH_SUSPEND_POSSIBLE
376 config KASAN_SHADOW_OFFSET
379 default 0xdffffc0000000000
381 config HAVE_INTEL_TXT
383 depends on INTEL_IOMMU && ACPI
387 depends on X86_32 && SMP
391 depends on X86_64 && SMP
393 config ARCH_SUPPORTS_UPROBES
396 config FIX_EARLYCON_MEM
399 config DYNAMIC_PHYSICAL_MASK
402 config PGTABLE_LEVELS
404 default 5 if X86_5LEVEL
409 config CC_HAS_SANE_STACKPROTECTOR
411 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
412 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
414 We have to make sure stack protector is unconditionally disabled if
415 the compiler produces broken code or if it does not let us control
416 the segment on 32-bit kernels.
418 menu "Processor type and features"
421 bool "Symmetric multi-processing support"
423 This enables support for systems with more than one CPU. If you have
424 a system with only one CPU, say N. If you have a system with more
427 If you say N here, the kernel will run on uni- and multiprocessor
428 machines, but will use only one CPU of a multiprocessor machine. If
429 you say Y here, the kernel will run on many, but not all,
430 uniprocessor machines. On a uniprocessor machine, the kernel
431 will run faster if you say N here.
433 Note that if you say Y here and choose architecture "586" or
434 "Pentium" under "Processor family", the kernel will not work on 486
435 architectures. Similarly, multiprocessor kernels for the "PPro"
436 architecture may not work on all Pentium based boards.
438 People using multiprocessor machines who say Y here should also say
439 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
440 Management" code will be disabled if you say Y here.
442 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
443 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
444 <http://www.tldp.org/docs.html#howto>.
446 If you don't know what to do here, say N.
449 bool "Support x2apic"
450 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
452 This enables x2apic support on CPUs that have this feature.
454 This allows 32-bit apic IDs (so it can support very large systems),
455 and accesses the local apic via MSRs not via mmio.
457 Some Intel systems circa 2022 and later are locked into x2APIC mode
458 and can not fall back to the legacy APIC modes if SGX or TDX are
459 enabled in the BIOS. They will boot with very reduced functionality
460 without enabling this option.
462 If you don't know what to do here, say N.
465 bool "Enable MPS table" if ACPI
467 depends on X86_LOCAL_APIC
469 For old smp systems that do not have proper acpi support. Newer systems
470 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
474 depends on X86_GOLDFISH
476 config X86_CPU_RESCTRL
477 bool "x86 CPU resource control support"
478 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
480 select PROC_CPU_RESCTRL if PROC_FS
482 Enable x86 CPU resource control support.
484 Provide support for the allocation and monitoring of system resources
487 Intel calls this Intel Resource Director Technology
488 (Intel(R) RDT). More information about RDT can be found in the
489 Intel x86 Architecture Software Developer Manual.
491 AMD calls this AMD Platform Quality of Service (AMD QoS).
492 More information about AMD QoS can be found in the AMD64 Technology
493 Platform Quality of Service Extensions manual.
499 bool "Support for big SMP systems with more than 8 CPUs"
502 This option is needed for the systems that have more than 8 CPUs.
504 config X86_EXTENDED_PLATFORM
505 bool "Support for extended (non-PC) x86 platforms"
508 If you disable this option then the kernel will only support
509 standard PC platforms. (which covers the vast majority of
512 If you enable this option then you'll be able to select support
513 for the following (non-PC) 32 bit x86 platforms:
514 Goldfish (Android emulator)
517 SGI 320/540 (Visual Workstation)
518 STA2X11-based (e.g. Northville)
519 Moorestown MID devices
521 If you have one of these systems, or if you want to build a
522 generic distribution kernel, say Y here - otherwise say N.
526 config X86_EXTENDED_PLATFORM
527 bool "Support for extended (non-PC) x86 platforms"
530 If you disable this option then the kernel will only support
531 standard PC platforms. (which covers the vast majority of
534 If you enable this option then you'll be able to select support
535 for the following (non-PC) 64 bit x86 platforms:
540 If you have one of these systems, or if you want to build a
541 generic distribution kernel, say Y here - otherwise say N.
543 # This is an alphabetically sorted list of 64 bit extended platforms
544 # Please maintain the alphabetic order if and when there are additions
546 bool "Numascale NumaChip"
548 depends on X86_EXTENDED_PLATFORM
551 depends on X86_X2APIC
552 depends on PCI_MMCONFIG
554 Adds support for Numascale NumaChip large-SMP systems. Needed to
555 enable more than ~168 cores.
556 If you don't have one of these, you should say N here.
560 select HYPERVISOR_GUEST
562 depends on X86_64 && PCI
563 depends on X86_EXTENDED_PLATFORM
566 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
567 supposed to run on these EM64T-based machines. Only choose this option
568 if you have one of these machines.
571 bool "SGI Ultraviolet"
573 depends on X86_EXTENDED_PLATFORM
576 depends on KEXEC_CORE
577 depends on X86_X2APIC
580 This option is needed in order to support SGI Ultraviolet systems.
581 If you don't have one of these, you should say N here.
583 # Following is an alphabetically sorted list of 32 bit extended platforms
584 # Please maintain the alphabetic order if and when there are additions
587 bool "Goldfish (Virtual Platform)"
588 depends on X86_EXTENDED_PLATFORM
590 Enable support for the Goldfish virtual platform used primarily
591 for Android development. Unless you are building for the Android
592 Goldfish emulator say N here.
595 bool "CE4100 TV platform"
597 depends on PCI_GODIRECT
598 depends on X86_IO_APIC
600 depends on X86_EXTENDED_PLATFORM
601 select X86_REBOOTFIXUPS
603 select OF_EARLY_FLATTREE
605 Select for the Intel CE media processor (CE4100) SOC.
606 This option compiles in support for the CE4100 SOC for settop
607 boxes and media devices.
610 bool "Intel MID platform support"
611 depends on X86_EXTENDED_PLATFORM
612 depends on X86_PLATFORM_DEVICES
614 depends on X86_64 || (PCI_GOANY && X86_32)
615 depends on X86_IO_APIC
620 Select to build a kernel capable of supporting Intel MID (Mobile
621 Internet Device) platform systems which do not have the PCI legacy
622 interfaces. If you are building for a PC class system say N here.
624 Intel MID platforms are based on an Intel processor and chipset which
625 consume less power than most of the x86 derivatives.
627 config X86_INTEL_QUARK
628 bool "Intel Quark platform support"
630 depends on X86_EXTENDED_PLATFORM
631 depends on X86_PLATFORM_DEVICES
635 depends on X86_IO_APIC
640 Select to include support for Quark X1000 SoC.
641 Say Y here if you have a Quark based system such as the Arduino
642 compatible Intel Galileo.
644 config X86_INTEL_LPSS
645 bool "Intel Low Power Subsystem Support"
646 depends on X86 && ACPI && PCI
651 Select to build support for Intel Low Power Subsystem such as
652 found on Intel Lynxpoint PCH. Selecting this option enables
653 things like clock tree (common clock framework) and pincontrol
654 which are needed by the LPSS peripheral drivers.
656 config X86_AMD_PLATFORM_DEVICE
657 bool "AMD ACPI2Platform devices support"
662 Select to interpret AMD specific ACPI device to platform device
663 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
664 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
665 implemented under PINCTRL subsystem.
668 tristate "Intel SoC IOSF Sideband support for SoC platforms"
671 This option enables sideband register access support for Intel SoC
672 platforms. On these platforms the IOSF sideband is used in lieu of
673 MSR's for some register accesses, mostly but not limited to thermal
674 and power. Drivers may query the availability of this device to
675 determine if they need the sideband in order to work on these
676 platforms. The sideband is available on the following SoC products.
677 This list is not meant to be exclusive.
682 You should say Y if you are running a kernel on one of these SoC's.
684 config IOSF_MBI_DEBUG
685 bool "Enable IOSF sideband access through debugfs"
686 depends on IOSF_MBI && DEBUG_FS
688 Select this option to expose the IOSF sideband access registers (MCR,
689 MDR, MCRX) through debugfs to write and read register information from
690 different units on the SoC. This is most useful for obtaining device
691 state information for debug and analysis. As this is a general access
692 mechanism, users of this option would have specific knowledge of the
693 device they want to access.
695 If you don't require the option or are in doubt, say N.
698 bool "RDC R-321x SoC"
700 depends on X86_EXTENDED_PLATFORM
702 select X86_REBOOTFIXUPS
704 This option is needed for RDC R-321x system-on-chip, also known
706 If you don't have one of these chips, you should say N here.
708 config X86_32_NON_STANDARD
709 bool "Support non-standard 32-bit SMP architectures"
710 depends on X86_32 && SMP
711 depends on X86_EXTENDED_PLATFORM
713 This option compiles in the bigsmp and STA2X11 default
714 subarchitectures. It is intended for a generic binary
715 kernel. If you select them all, kernel will probe it one by
716 one and will fallback to default.
718 # Alphabetically sorted list of Non standard 32 bit platforms
720 config X86_SUPPORTS_MEMORY_FAILURE
722 # MCE code calls memory_failure():
724 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
725 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
726 depends on X86_64 || !SPARSEMEM
727 select ARCH_SUPPORTS_MEMORY_FAILURE
730 bool "STA2X11 Companion Chip Support"
731 depends on X86_32_NON_STANDARD && PCI
736 This adds support for boards based on the STA2X11 IO-Hub,
737 a.k.a. "ConneXt". The chip is used in place of the standard
738 PC chipset, so all "standard" peripherals are missing. If this
739 option is selected the kernel will still be able to boot on
740 standard PC machines.
743 tristate "Eurobraille/Iris poweroff module"
746 The Iris machines from EuroBraille do not have APM or ACPI support
747 to shut themselves down properly. A special I/O sequence is
748 needed to do so, which is what this module does at
751 This is only for Iris machines from EuroBraille.
755 config SCHED_OMIT_FRAME_POINTER
757 prompt "Single-depth WCHAN output"
760 Calculate simpler /proc/<PID>/wchan values. If this option
761 is disabled then wchan values will recurse back to the
762 caller function. This provides more accurate wchan values,
763 at the expense of slightly more scheduling overhead.
765 If in doubt, say "Y".
767 menuconfig HYPERVISOR_GUEST
768 bool "Linux guest support"
770 Say Y here to enable options for running Linux under various hyper-
771 visors. This option enables basic hypervisor detection and platform
774 If you say N, all options in this submenu will be skipped and
775 disabled, and Linux guest support won't be built in.
780 bool "Enable paravirtualization code"
781 depends on HAVE_STATIC_CALL
783 This changes the kernel so it can modify itself when it is run
784 under a hypervisor, potentially improving performance significantly
785 over full virtualization. However, when run without a hypervisor
786 the kernel is theoretically slower and slightly larger.
791 config PARAVIRT_DEBUG
792 bool "paravirt-ops debugging"
793 depends on PARAVIRT && DEBUG_KERNEL
795 Enable to debug paravirt_ops internals. Specifically, BUG if
796 a paravirt_op is missing when it is called.
798 config PARAVIRT_SPINLOCKS
799 bool "Paravirtualization layer for spinlocks"
800 depends on PARAVIRT && SMP
802 Paravirtualized spinlocks allow a pvops backend to replace the
803 spinlock implementation with something virtualization-friendly
804 (for example, block the virtual CPU rather than spinning).
806 It has a minimal impact on native kernels and gives a nice performance
807 benefit on paravirtualized KVM / Xen kernels.
809 If you are unsure how to answer this question, answer Y.
811 config X86_HV_CALLBACK_VECTOR
814 source "arch/x86/xen/Kconfig"
817 bool "KVM Guest support (including kvmclock)"
819 select PARAVIRT_CLOCK
820 select ARCH_CPUIDLE_HALTPOLL
821 select X86_HV_CALLBACK_VECTOR
824 This option enables various optimizations for running under the KVM
825 hypervisor. It includes a paravirtualized clock, so that instead
826 of relying on a PIT (or probably other) emulation by the
827 underlying device model, the host provides the guest with
828 timing infrastructure such as time of day, and system time
830 config ARCH_CPUIDLE_HALTPOLL
832 prompt "Disable host haltpoll when loading haltpoll driver"
834 If virtualized under KVM, disable host haltpoll.
837 bool "Support for running PVH guests"
839 This option enables the PVH entry point for guest virtual machines
840 as specified in the x86/HVM direct boot ABI.
842 config PARAVIRT_TIME_ACCOUNTING
843 bool "Paravirtual steal time accounting"
846 Select this option to enable fine granularity task steal time
847 accounting. Time spent executing other tasks in parallel with
848 the current vCPU is discounted from the vCPU power. To account for
849 that, there can be a small performance impact.
851 If in doubt, say N here.
853 config PARAVIRT_CLOCK
856 config JAILHOUSE_GUEST
857 bool "Jailhouse non-root cell support"
858 depends on X86_64 && PCI
861 This option allows to run Linux as guest in a Jailhouse non-root
862 cell. You can leave this option disabled if you only want to start
863 Jailhouse and run Linux afterwards in the root cell.
866 bool "ACRN Guest support"
868 select X86_HV_CALLBACK_VECTOR
870 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
871 a flexible, lightweight reference open-source hypervisor, built with
872 real-time and safety-criticality in mind. It is built for embedded
873 IOT with small footprint and real-time features. More details can be
874 found in https://projectacrn.org/.
876 config INTEL_TDX_GUEST
877 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
878 depends on X86_64 && CPU_SUP_INTEL
879 depends on X86_X2APIC
881 select ARCH_HAS_CC_PLATFORM
882 select X86_MEM_ENCRYPT
884 select UNACCEPTED_MEMORY
886 Support running as a guest under Intel TDX. Without this support,
887 the guest kernel can not boot or run under TDX.
888 TDX includes memory encryption and integrity capabilities
889 which protect the confidentiality and integrity of guest
890 memory contents and CPU state. TDX guests are protected from
891 some attacks from the VMM.
893 endif # HYPERVISOR_GUEST
895 source "arch/x86/Kconfig.cpu"
899 prompt "HPET Timer Support" if X86_32
901 Use the IA-PC HPET (High Precision Event Timer) to manage
902 time in preference to the PIT and RTC, if a HPET is
904 HPET is the next generation timer replacing legacy 8254s.
905 The HPET provides a stable time base on SMP
906 systems, unlike the TSC, but it is more expensive to access,
907 as it is off-chip. The interface used is documented
908 in the HPET spec, revision 1.
910 You can safely choose Y here. However, HPET will only be
911 activated if the platform and the BIOS support this feature.
912 Otherwise the 8254 will be used for timing services.
914 Choose N to continue using the legacy 8254 timer.
916 config HPET_EMULATE_RTC
918 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
920 # Mark as expert because too many people got it wrong.
921 # The code disables itself when not needed.
924 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
925 bool "Enable DMI scanning" if EXPERT
927 Enabled scanning of DMI to identify machine quirks. Say Y
928 here unless you have verified that your setup is not
929 affected by entries in the DMI blacklist. Required by PNP
933 bool "Old AMD GART IOMMU support"
937 depends on X86_64 && PCI && AMD_NB
939 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
940 GART based hardware IOMMUs.
942 The GART supports full DMA access for devices with 32-bit access
943 limitations, on systems with more than 3 GB. This is usually needed
944 for USB, sound, many IDE/SATA chipsets and some other devices.
946 Newer systems typically have a modern AMD IOMMU, supported via
947 the CONFIG_AMD_IOMMU=y config option.
949 In normal configurations this driver is only active when needed:
950 there's more than 3 GB of memory and the system contains a
951 32-bit limited device.
955 config BOOT_VESA_SUPPORT
958 If true, at least one selected framebuffer driver can take advantage
959 of VESA video modes set at an early boot stage via the vga= parameter.
962 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
963 depends on X86_64 && SMP && DEBUG_KERNEL
964 select CPUMASK_OFFSTACK
966 Enable maximum number of CPUS and NUMA Nodes for this architecture.
970 # The maximum number of CPUs supported:
972 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
973 # and which can be configured interactively in the
974 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
976 # The ranges are different on 32-bit and 64-bit kernels, depending on
977 # hardware capabilities and scalability features of the kernel.
979 # ( If MAXSMP is enabled we just use the highest possible value and disable
980 # interactive configuration. )
983 config NR_CPUS_RANGE_BEGIN
985 default NR_CPUS_RANGE_END if MAXSMP
989 config NR_CPUS_RANGE_END
992 default 64 if SMP && X86_BIGSMP
993 default 8 if SMP && !X86_BIGSMP
996 config NR_CPUS_RANGE_END
999 default 8192 if SMP && CPUMASK_OFFSTACK
1000 default 512 if SMP && !CPUMASK_OFFSTACK
1003 config NR_CPUS_DEFAULT
1006 default 32 if X86_BIGSMP
1010 config NR_CPUS_DEFAULT
1013 default 8192 if MAXSMP
1018 int "Maximum number of CPUs" if SMP && !MAXSMP
1019 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1020 default NR_CPUS_DEFAULT
1022 This allows you to specify the maximum number of CPUs which this
1023 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1024 supported value is 8192, otherwise the maximum value is 512. The
1025 minimum value which makes sense is 2.
1027 This is purely to save memory: each supported CPU adds about 8KB
1028 to the kernel image.
1030 config SCHED_CLUSTER
1031 bool "Cluster scheduler support"
1035 Cluster scheduler support improves the CPU scheduler's decision
1036 making when dealing with machines that have clusters of CPUs.
1037 Cluster usually means a couple of CPUs which are placed closely
1038 by sharing mid-level caches, last-level cache tags or internal
1046 prompt "Multi-core scheduler support"
1049 Multi-core scheduler support improves the CPU scheduler's decision
1050 making when dealing with multi-core CPU chips at a cost of slightly
1051 increased overhead in some places. If unsure say N here.
1053 config SCHED_MC_PRIO
1054 bool "CPU core priorities scheduler support"
1055 depends on SCHED_MC && CPU_SUP_INTEL
1056 select X86_INTEL_PSTATE
1060 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1061 core ordering determined at manufacturing time, which allows
1062 certain cores to reach higher turbo frequencies (when running
1063 single threaded workloads) than others.
1065 Enabling this kernel feature teaches the scheduler about
1066 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1067 scheduler's CPU selection logic accordingly, so that higher
1068 overall system performance can be achieved.
1070 This feature will have no effect on CPUs without this feature.
1072 If unsure say Y here.
1076 depends on !SMP && X86_LOCAL_APIC
1079 bool "Local APIC support on uniprocessors" if !PCI_MSI
1081 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1083 A local APIC (Advanced Programmable Interrupt Controller) is an
1084 integrated interrupt controller in the CPU. If you have a single-CPU
1085 system which has a processor with a local APIC, you can say Y here to
1086 enable and use it. If you say Y here even though your machine doesn't
1087 have a local APIC, then the kernel will still run with no slowdown at
1088 all. The local APIC supports CPU-generated self-interrupts (timer,
1089 performance counters), and the NMI watchdog which detects hard
1092 config X86_UP_IOAPIC
1093 bool "IO-APIC support on uniprocessors"
1094 depends on X86_UP_APIC
1096 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1097 SMP-capable replacement for PC-style interrupt controllers. Most
1098 SMP systems and many recent uniprocessor systems have one.
1100 If you have a single-CPU system with an IO-APIC, you can say Y here
1101 to use it. If you say Y here even though your machine doesn't have
1102 an IO-APIC, then the kernel will still run with no slowdown at all.
1104 config X86_LOCAL_APIC
1106 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1107 select IRQ_DOMAIN_HIERARCHY
1111 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1113 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1114 bool "Reroute for broken boot IRQs"
1115 depends on X86_IO_APIC
1117 This option enables a workaround that fixes a source of
1118 spurious interrupts. This is recommended when threaded
1119 interrupt handling is used on systems where the generation of
1120 superfluous "boot interrupts" cannot be disabled.
1122 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1123 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1124 kernel does during interrupt handling). On chipsets where this
1125 boot IRQ generation cannot be disabled, this workaround keeps
1126 the original IRQ line masked so that only the equivalent "boot
1127 IRQ" is delivered to the CPUs. The workaround also tells the
1128 kernel to set up the IRQ handler on the boot IRQ line. In this
1129 way only one interrupt is delivered to the kernel. Otherwise
1130 the spurious second interrupt may cause the kernel to bring
1131 down (vital) interrupt lines.
1133 Only affects "broken" chipsets. Interrupt sharing may be
1134 increased on these systems.
1137 bool "Machine Check / overheating reporting"
1138 select GENERIC_ALLOCATOR
1141 Machine Check support allows the processor to notify the
1142 kernel if it detects a problem (e.g. overheating, data corruption).
1143 The action the kernel takes depends on the severity of the problem,
1144 ranging from warning messages to halting the machine.
1146 config X86_MCELOG_LEGACY
1147 bool "Support for deprecated /dev/mcelog character device"
1150 Enable support for /dev/mcelog which is needed by the old mcelog
1151 userspace logging daemon. Consider switching to the new generation
1154 config X86_MCE_INTEL
1156 prompt "Intel MCE features"
1157 depends on X86_MCE && X86_LOCAL_APIC
1159 Additional support for intel specific MCE features such as
1160 the thermal monitor.
1164 prompt "AMD MCE features"
1165 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1167 Additional support for AMD specific MCE features such as
1168 the DRAM Error Threshold.
1170 config X86_ANCIENT_MCE
1171 bool "Support for old Pentium 5 / WinChip machine checks"
1172 depends on X86_32 && X86_MCE
1174 Include support for machine check handling on old Pentium 5 or WinChip
1175 systems. These typically need to be enabled explicitly on the command
1178 config X86_MCE_THRESHOLD
1179 depends on X86_MCE_AMD || X86_MCE_INTEL
1182 config X86_MCE_INJECT
1183 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1184 tristate "Machine check injector support"
1186 Provide support for injecting machine checks for testing purposes.
1187 If you don't know what a machine check is and you don't do kernel
1188 QA it is safe to say n.
1190 source "arch/x86/events/Kconfig"
1192 config X86_LEGACY_VM86
1193 bool "Legacy VM86 support"
1196 This option allows user programs to put the CPU into V8086
1197 mode, which is an 80286-era approximation of 16-bit real mode.
1199 Some very old versions of X and/or vbetool require this option
1200 for user mode setting. Similarly, DOSEMU will use it if
1201 available to accelerate real mode DOS programs. However, any
1202 recent version of DOSEMU, X, or vbetool should be fully
1203 functional even without kernel VM86 support, as they will all
1204 fall back to software emulation. Nevertheless, if you are using
1205 a 16-bit DOS program where 16-bit performance matters, vm86
1206 mode might be faster than emulation and you might want to
1209 Note that any app that works on a 64-bit kernel is unlikely to
1210 need this option, as 64-bit kernels don't, and can't, support
1211 V8086 mode. This option is also unrelated to 16-bit protected
1212 mode and is not needed to run most 16-bit programs under Wine.
1214 Enabling this option increases the complexity of the kernel
1215 and slows down exception handling a tiny bit.
1217 If unsure, say N here.
1221 default X86_LEGACY_VM86
1224 bool "Enable support for 16-bit segments" if EXPERT
1226 depends on MODIFY_LDT_SYSCALL
1228 This option is required by programs like Wine to run 16-bit
1229 protected mode legacy code on x86 processors. Disabling
1230 this option saves about 300 bytes on i386, or around 6K text
1231 plus 16K runtime memory on x86-64,
1235 depends on X86_16BIT && X86_32
1239 depends on X86_16BIT && X86_64
1241 config X86_VSYSCALL_EMULATION
1242 bool "Enable vsyscall emulation" if EXPERT
1246 This enables emulation of the legacy vsyscall page. Disabling
1247 it is roughly equivalent to booting with vsyscall=none, except
1248 that it will also disable the helpful warning if a program
1249 tries to use a vsyscall. With this option set to N, offending
1250 programs will just segfault, citing addresses of the form
1253 This option is required by many programs built before 2013, and
1254 care should be used even with newer programs if set to N.
1256 Disabling this option saves about 7K of kernel size and
1257 possibly 4K of additional runtime pagetable memory.
1259 config X86_IOPL_IOPERM
1260 bool "IOPERM and IOPL Emulation"
1263 This enables the ioperm() and iopl() syscalls which are necessary
1264 for legacy applications.
1266 Legacy IOPL support is an overbroad mechanism which allows user
1267 space aside of accessing all 65536 I/O ports also to disable
1268 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1269 capabilities and permission from potentially active security
1272 The emulation restricts the functionality of the syscall to
1273 only allowing the full range I/O port access, but prevents the
1274 ability to disable interrupts from user space which would be
1275 granted if the hardware IOPL mechanism would be used.
1278 tristate "Toshiba Laptop support"
1281 This adds a driver to safely access the System Management Mode of
1282 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1283 not work on models with a Phoenix BIOS. The System Management Mode
1284 is used to set the BIOS and power saving options on Toshiba portables.
1286 For information on utilities to make use of this driver see the
1287 Toshiba Linux utilities web site at:
1288 <http://www.buzzard.org.uk/toshiba/>.
1290 Say Y if you intend to run this kernel on a Toshiba portable.
1293 config X86_REBOOTFIXUPS
1294 bool "Enable X86 board specific fixups for reboot"
1297 This enables chipset and/or board specific fixups to be done
1298 in order to get reboot to work correctly. This is only needed on
1299 some combinations of hardware and BIOS. The symptom, for which
1300 this config is intended, is when reboot ends with a stalled/hung
1303 Currently, the only fixup is for the Geode machines using
1304 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1306 Say Y if you want to enable the fixup. Currently, it's safe to
1307 enable this option even if you don't need it.
1311 bool "CPU microcode loading support"
1313 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1315 If you say Y here, you will be able to update the microcode on
1316 Intel and AMD processors. The Intel support is for the IA32 family,
1317 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1318 AMD support is for families 0x10 and later. You will obviously need
1319 the actual microcode binary data itself which is not shipped with
1322 The preferred method to load microcode from a detached initrd is described
1323 in Documentation/arch/x86/microcode.rst. For that you need to enable
1324 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1325 initrd for microcode blobs.
1327 In addition, you can build the microcode into the kernel. For that you
1328 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1331 config MICROCODE_INTEL
1332 bool "Intel microcode loading support"
1333 depends on CPU_SUP_INTEL && MICROCODE
1336 This options enables microcode patch loading support for Intel
1339 For the current Intel microcode data package go to
1340 <https://downloadcenter.intel.com> and search for
1341 'Linux Processor Microcode Data File'.
1343 config MICROCODE_AMD
1344 bool "AMD microcode loading support"
1345 depends on CPU_SUP_AMD && MICROCODE
1347 If you select this option, microcode patch loading support for AMD
1348 processors will be enabled.
1350 config MICROCODE_LATE_LOADING
1351 bool "Late microcode loading (DANGEROUS)"
1353 depends on MICROCODE
1355 Loading microcode late, when the system is up and executing instructions
1356 is a tricky business and should be avoided if possible. Just the sequence
1357 of synchronizing all cores and SMT threads is one fragile dance which does
1358 not guarantee that cores might not softlock after the loading. Therefore,
1359 use this at your own risk. Late loading taints the kernel too.
1362 tristate "/dev/cpu/*/msr - Model-specific register support"
1364 This device gives privileged processes access to the x86
1365 Model-Specific Registers (MSRs). It is a character device with
1366 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1367 MSR accesses are directed to a specific CPU on multi-processor
1371 tristate "/dev/cpu/*/cpuid - CPU information support"
1373 This device gives processes access to the x86 CPUID instruction to
1374 be executed on a specific processor. It is a character device
1375 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1379 prompt "High Memory Support"
1386 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1387 However, the address space of 32-bit x86 processors is only 4
1388 Gigabytes large. That means that, if you have a large amount of
1389 physical memory, not all of it can be "permanently mapped" by the
1390 kernel. The physical memory that's not permanently mapped is called
1393 If you are compiling a kernel which will never run on a machine with
1394 more than 1 Gigabyte total physical RAM, answer "off" here (default
1395 choice and suitable for most users). This will result in a "3GB/1GB"
1396 split: 3GB are mapped so that each process sees a 3GB virtual memory
1397 space and the remaining part of the 4GB virtual memory space is used
1398 by the kernel to permanently map as much physical memory as
1401 If the machine has between 1 and 4 Gigabytes physical RAM, then
1404 If more than 4 Gigabytes is used then answer "64GB" here. This
1405 selection turns Intel PAE (Physical Address Extension) mode on.
1406 PAE implements 3-level paging on IA32 processors. PAE is fully
1407 supported by Linux, PAE mode is implemented on all recent Intel
1408 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1409 then the kernel will not boot on CPUs that don't support PAE!
1411 The actual amount of total physical memory will either be
1412 auto detected or can be forced by using a kernel command line option
1413 such as "mem=256M". (Try "man bootparam" or see the documentation of
1414 your boot loader (lilo or loadlin) about how to pass options to the
1415 kernel at boot time.)
1417 If unsure, say "off".
1422 Select this if you have a 32-bit processor and between 1 and 4
1423 gigabytes of physical RAM.
1427 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1430 Select this if you have a 32-bit processor and more than 4
1431 gigabytes of physical RAM.
1436 prompt "Memory split" if EXPERT
1440 Select the desired split between kernel and user memory.
1442 If the address range available to the kernel is less than the
1443 physical memory installed, the remaining memory will be available
1444 as "high memory". Accessing high memory is a little more costly
1445 than low memory, as it needs to be mapped into the kernel first.
1446 Note that increasing the kernel address space limits the range
1447 available to user programs, making the address space there
1448 tighter. Selecting anything other than the default 3G/1G split
1449 will also likely make your kernel incompatible with binary-only
1452 If you are not absolutely sure what you are doing, leave this
1456 bool "3G/1G user/kernel split"
1457 config VMSPLIT_3G_OPT
1459 bool "3G/1G user/kernel split (for full 1G low memory)"
1461 bool "2G/2G user/kernel split"
1462 config VMSPLIT_2G_OPT
1464 bool "2G/2G user/kernel split (for full 2G low memory)"
1466 bool "1G/3G user/kernel split"
1471 default 0xB0000000 if VMSPLIT_3G_OPT
1472 default 0x80000000 if VMSPLIT_2G
1473 default 0x78000000 if VMSPLIT_2G_OPT
1474 default 0x40000000 if VMSPLIT_1G
1480 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1483 bool "PAE (Physical Address Extension) Support"
1484 depends on X86_32 && !HIGHMEM4G
1485 select PHYS_ADDR_T_64BIT
1488 PAE is required for NX support, and furthermore enables
1489 larger swapspace support for non-overcommit purposes. It
1490 has the cost of more pagetable lookup overhead, and also
1491 consumes more pagetable space per process.
1494 bool "Enable 5-level page tables support"
1496 select DYNAMIC_MEMORY_LAYOUT
1497 select SPARSEMEM_VMEMMAP
1500 5-level paging enables access to larger address space:
1501 up to 128 PiB of virtual address space and 4 PiB of
1502 physical address space.
1504 It will be supported by future Intel CPUs.
1506 A kernel with the option enabled can be booted on machines that
1507 support 4- or 5-level paging.
1509 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1514 config X86_DIRECT_GBPAGES
1518 Certain kernel features effectively disable kernel
1519 linear 1 GB mappings (even if the CPU otherwise
1520 supports them), so don't confuse the user by printing
1521 that we have them enabled.
1523 config X86_CPA_STATISTICS
1524 bool "Enable statistic for Change Page Attribute"
1527 Expose statistics about the Change Page Attribute mechanism, which
1528 helps to determine the effectiveness of preserving large and huge
1529 page mappings when mapping protections are changed.
1531 config X86_MEM_ENCRYPT
1532 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1533 select DYNAMIC_PHYSICAL_MASK
1536 config AMD_MEM_ENCRYPT
1537 bool "AMD Secure Memory Encryption (SME) support"
1538 depends on X86_64 && CPU_SUP_AMD
1540 select DMA_COHERENT_POOL
1541 select ARCH_USE_MEMREMAP_PROT
1542 select INSTRUCTION_DECODER
1543 select ARCH_HAS_CC_PLATFORM
1544 select X86_MEM_ENCRYPT
1545 select UNACCEPTED_MEMORY
1547 Say yes to enable support for the encryption of system memory.
1548 This requires an AMD processor that supports Secure Memory
1551 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1552 bool "Activate AMD Secure Memory Encryption (SME) by default"
1553 depends on AMD_MEM_ENCRYPT
1555 Say yes to have system memory encrypted by default if running on
1556 an AMD processor that supports Secure Memory Encryption (SME).
1558 If set to Y, then the encryption of system memory can be
1559 deactivated with the mem_encrypt=off command line option.
1561 If set to N, then the encryption of system memory can be
1562 activated with the mem_encrypt=on command line option.
1564 # Common NUMA Features
1566 bool "NUMA Memory Allocation and Scheduler Support"
1568 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1569 default y if X86_BIGSMP
1570 select USE_PERCPU_NUMA_NODE_ID
1572 Enable NUMA (Non-Uniform Memory Access) support.
1574 The kernel will try to allocate memory used by a CPU on the
1575 local memory controller of the CPU and add some more
1576 NUMA awareness to the kernel.
1578 For 64-bit this is recommended if the system is Intel Core i7
1579 (or later), AMD Opteron, or EM64T NUMA.
1581 For 32-bit this is only needed if you boot a 32-bit
1582 kernel on a 64-bit NUMA platform.
1584 Otherwise, you should say N.
1588 prompt "Old style AMD Opteron NUMA detection"
1589 depends on X86_64 && NUMA && PCI
1591 Enable AMD NUMA node topology detection. You should say Y here if
1592 you have a multi processor AMD system. This uses an old method to
1593 read the NUMA configuration directly from the builtin Northbridge
1594 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1595 which also takes priority if both are compiled in.
1597 config X86_64_ACPI_NUMA
1599 prompt "ACPI NUMA detection"
1600 depends on X86_64 && NUMA && ACPI && PCI
1603 Enable ACPI SRAT based node topology detection.
1606 bool "NUMA emulation"
1609 Enable NUMA emulation. A flat machine will be split
1610 into virtual nodes when booted with "numa=fake=N", where N is the
1611 number of nodes. This is only useful for debugging.
1614 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1616 default "10" if MAXSMP
1617 default "6" if X86_64
1621 Specify the maximum number of NUMA Nodes available on the target
1622 system. Increases memory reserved to accommodate various tables.
1624 config ARCH_FLATMEM_ENABLE
1626 depends on X86_32 && !NUMA
1628 config ARCH_SPARSEMEM_ENABLE
1630 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1631 select SPARSEMEM_STATIC if X86_32
1632 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1634 config ARCH_SPARSEMEM_DEFAULT
1635 def_bool X86_64 || (NUMA && X86_32)
1637 config ARCH_SELECT_MEMORY_MODEL
1639 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1641 config ARCH_MEMORY_PROBE
1642 bool "Enable sysfs memory/probe interface"
1643 depends on MEMORY_HOTPLUG
1645 This option enables a sysfs memory/probe interface for testing.
1646 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1647 If you are unsure how to answer this question, answer N.
1649 config ARCH_PROC_KCORE_TEXT
1651 depends on X86_64 && PROC_KCORE
1653 config ILLEGAL_POINTER_VALUE
1656 default 0xdead000000000000 if X86_64
1658 config X86_PMEM_LEGACY_DEVICE
1661 config X86_PMEM_LEGACY
1662 tristate "Support non-standard NVDIMMs and ADR protected memory"
1663 depends on PHYS_ADDR_T_64BIT
1665 select X86_PMEM_LEGACY_DEVICE
1666 select NUMA_KEEP_MEMINFO if NUMA
1669 Treat memory marked using the non-standard e820 type of 12 as used
1670 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1671 The kernel will offer these regions to the 'pmem' driver so
1672 they can be used for persistent storage.
1677 bool "Allocate 3rd-level pagetables from highmem"
1680 The VM uses one page table entry for each page of physical memory.
1681 For systems with a lot of RAM, this can be wasteful of precious
1682 low memory. Setting this option will put user-space page table
1683 entries in high memory.
1685 config X86_CHECK_BIOS_CORRUPTION
1686 bool "Check for low memory corruption"
1688 Periodically check for memory corruption in low memory, which
1689 is suspected to be caused by BIOS. Even when enabled in the
1690 configuration, it is disabled at runtime. Enable it by
1691 setting "memory_corruption_check=1" on the kernel command
1692 line. By default it scans the low 64k of memory every 60
1693 seconds; see the memory_corruption_check_size and
1694 memory_corruption_check_period parameters in
1695 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1697 When enabled with the default parameters, this option has
1698 almost no overhead, as it reserves a relatively small amount
1699 of memory and scans it infrequently. It both detects corruption
1700 and prevents it from affecting the running system.
1702 It is, however, intended as a diagnostic tool; if repeatable
1703 BIOS-originated corruption always affects the same memory,
1704 you can use memmap= to prevent the kernel from using that
1707 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1708 bool "Set the default setting of memory_corruption_check"
1709 depends on X86_CHECK_BIOS_CORRUPTION
1712 Set whether the default state of memory_corruption_check is
1715 config MATH_EMULATION
1717 depends on MODIFY_LDT_SYSCALL
1718 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1720 Linux can emulate a math coprocessor (used for floating point
1721 operations) if you don't have one. 486DX and Pentium processors have
1722 a math coprocessor built in, 486SX and 386 do not, unless you added
1723 a 487DX or 387, respectively. (The messages during boot time can
1724 give you some hints here ["man dmesg"].) Everyone needs either a
1725 coprocessor or this emulation.
1727 If you don't have a math coprocessor, you need to say Y here; if you
1728 say Y here even though you have a coprocessor, the coprocessor will
1729 be used nevertheless. (This behavior can be changed with the kernel
1730 command line option "no387", which comes handy if your coprocessor
1731 is broken. Try "man bootparam" or see the documentation of your boot
1732 loader (lilo or loadlin) about how to pass options to the kernel at
1733 boot time.) This means that it is a good idea to say Y here if you
1734 intend to use this kernel on different machines.
1736 More information about the internals of the Linux math coprocessor
1737 emulation can be found in <file:arch/x86/math-emu/README>.
1739 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1740 kernel, it won't hurt.
1744 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1746 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1747 the Memory Type Range Registers (MTRRs) may be used to control
1748 processor access to memory ranges. This is most useful if you have
1749 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1750 allows bus write transfers to be combined into a larger transfer
1751 before bursting over the PCI/AGP bus. This can increase performance
1752 of image write operations 2.5 times or more. Saying Y here creates a
1753 /proc/mtrr file which may be used to manipulate your processor's
1754 MTRRs. Typically the X server should use this.
1756 This code has a reasonably generic interface so that similar
1757 control registers on other processors can be easily supported
1760 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1761 Registers (ARRs) which provide a similar functionality to MTRRs. For
1762 these, the ARRs are used to emulate the MTRRs.
1763 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1764 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1765 write-combining. All of these processors are supported by this code
1766 and it makes sense to say Y here if you have one of them.
1768 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1769 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1770 can lead to all sorts of problems, so it's good to say Y here.
1772 You can safely say Y even if your machine doesn't have MTRRs, you'll
1773 just add about 9 KB to your kernel.
1775 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1777 config MTRR_SANITIZER
1779 prompt "MTRR cleanup support"
1782 Convert MTRR layout from continuous to discrete, so X drivers can
1783 add writeback entries.
1785 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1786 The largest mtrr entry size for a continuous block can be set with
1791 config MTRR_SANITIZER_ENABLE_DEFAULT
1792 int "MTRR cleanup enable value (0-1)"
1795 depends on MTRR_SANITIZER
1797 Enable mtrr cleanup default value
1799 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1800 int "MTRR cleanup spare reg num (0-7)"
1803 depends on MTRR_SANITIZER
1805 mtrr cleanup spare entries default, it can be changed via
1806 mtrr_spare_reg_nr=N on the kernel command line.
1810 prompt "x86 PAT support" if EXPERT
1813 Use PAT attributes to setup page level cache control.
1815 PATs are the modern equivalents of MTRRs and are much more
1816 flexible than MTRRs.
1818 Say N here if you see bootup problems (boot crash, boot hang,
1819 spontaneous reboots) or a non-working video driver.
1823 config ARCH_USES_PG_UNCACHED
1829 prompt "User Mode Instruction Prevention" if EXPERT
1831 User Mode Instruction Prevention (UMIP) is a security feature in
1832 some x86 processors. If enabled, a general protection fault is
1833 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1834 executed in user mode. These instructions unnecessarily expose
1835 information about the hardware state.
1837 The vast majority of applications do not use these instructions.
1838 For the very few that do, software emulation is provided in
1839 specific cases in protected and virtual-8086 modes. Emulated
1843 # GCC >= 9 and binutils >= 2.29
1844 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1846 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1847 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1848 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1849 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1852 config X86_KERNEL_IBT
1853 prompt "Indirect Branch Tracking"
1855 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1856 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1857 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1860 Build the kernel with support for Indirect Branch Tracking, a
1861 hardware support course-grain forward-edge Control Flow Integrity
1862 protection. It enforces that all indirect calls must land on
1863 an ENDBR instruction, as such, the compiler will instrument the
1864 code with them to make this happen.
1866 In addition to building the kernel with IBT, seal all functions that
1867 are not indirect call targets, avoiding them ever becoming one.
1869 This requires LTO like objtool runs and will slow down the build. It
1870 does significantly reduce the number of ENDBR instructions in the
1873 config X86_INTEL_MEMORY_PROTECTION_KEYS
1874 prompt "Memory Protection Keys"
1876 # Note: only available in 64-bit mode
1877 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1878 select ARCH_USES_HIGH_VMA_FLAGS
1879 select ARCH_HAS_PKEYS
1881 Memory Protection Keys provides a mechanism for enforcing
1882 page-based protections, but without requiring modification of the
1883 page tables when an application changes protection domains.
1885 For details, see Documentation/core-api/protection-keys.rst
1890 prompt "TSX enable mode"
1891 depends on CPU_SUP_INTEL
1892 default X86_INTEL_TSX_MODE_OFF
1894 Intel's TSX (Transactional Synchronization Extensions) feature
1895 allows to optimize locking protocols through lock elision which
1896 can lead to a noticeable performance boost.
1898 On the other hand it has been shown that TSX can be exploited
1899 to form side channel attacks (e.g. TAA) and chances are there
1900 will be more of those attacks discovered in the future.
1902 Therefore TSX is not enabled by default (aka tsx=off). An admin
1903 might override this decision by tsx=on the command line parameter.
1904 Even with TSX enabled, the kernel will attempt to enable the best
1905 possible TAA mitigation setting depending on the microcode available
1906 for the particular machine.
1908 This option allows to set the default tsx mode between tsx=on, =off
1909 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1912 Say off if not sure, auto if TSX is in use but it should be used on safe
1913 platforms or on if TSX is in use and the security aspect of tsx is not
1916 config X86_INTEL_TSX_MODE_OFF
1919 TSX is disabled if possible - equals to tsx=off command line parameter.
1921 config X86_INTEL_TSX_MODE_ON
1924 TSX is always enabled on TSX capable HW - equals the tsx=on command
1927 config X86_INTEL_TSX_MODE_AUTO
1930 TSX is enabled on TSX capable HW that is believed to be safe against
1931 side channel attacks- equals the tsx=auto command line parameter.
1935 bool "Software Guard eXtensions (SGX)"
1936 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1938 depends on CRYPTO_SHA256=y
1940 select NUMA_KEEP_MEMINFO if NUMA
1943 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1944 that can be used by applications to set aside private regions of code
1945 and data, referred to as enclaves. An enclave's private memory can
1946 only be accessed by code running within the enclave. Accesses from
1947 outside the enclave, including other enclaves, are disallowed by
1953 bool "EFI runtime service support"
1956 select EFI_RUNTIME_WRAPPERS
1957 select ARCH_USE_MEMREMAP_PROT
1959 This enables the kernel to use EFI runtime services that are
1960 available (such as the EFI variable services).
1962 This option is only useful on systems that have EFI firmware.
1963 In addition, you should use the latest ELILO loader available
1964 at <http://elilo.sourceforge.net> in order to take advantage
1965 of EFI runtime services. However, even with this option, the
1966 resultant kernel should continue to boot on existing non-EFI
1970 bool "EFI stub support"
1974 This kernel feature allows a bzImage to be loaded directly
1975 by EFI firmware without the use of a bootloader.
1977 See Documentation/admin-guide/efi-stub.rst for more information.
1979 config EFI_HANDOVER_PROTOCOL
1980 bool "EFI handover protocol (DEPRECATED)"
1984 Select this in order to include support for the deprecated EFI
1985 handover protocol, which defines alternative entry points into the
1986 EFI stub. This is a practice that has no basis in the UEFI
1987 specification, and requires a priori knowledge on the part of the
1988 bootloader about Linux/x86 specific ways of passing the command line
1989 and initrd, and where in memory those assets may be loaded.
1991 If in doubt, say Y. Even though the corresponding support is not
1992 present in upstream GRUB or other bootloaders, most distros build
1993 GRUB with numerous downstream patches applied, and may rely on the
1994 handover protocol as as result.
1997 bool "EFI mixed-mode support"
1998 depends on EFI_STUB && X86_64
2000 Enabling this feature allows a 64-bit kernel to be booted
2001 on a 32-bit firmware, provided that your CPU supports 64-bit
2004 Note that it is not possible to boot a mixed-mode enabled
2005 kernel via the EFI boot stub - a bootloader that supports
2006 the EFI handover protocol must be used.
2010 config EFI_FAKE_MEMMAP
2011 bool "Enable EFI fake memory map"
2014 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2015 this parameter, you can add arbitrary attribute to specific memory
2016 range by updating original (firmware provided) EFI memmap. This is
2017 useful for debugging of EFI memmap related feature, e.g., Address
2018 Range Mirroring feature.
2020 config EFI_MAX_FAKE_MEM
2021 int "maximum allowable number of ranges in efi_fake_mem boot option"
2022 depends on EFI_FAKE_MEMMAP
2026 Maximum allowable number of ranges in efi_fake_mem boot option.
2027 Ranges can be set up to this value using comma-separated list.
2028 The default value is 8.
2030 config EFI_RUNTIME_MAP
2031 bool "Export EFI runtime maps to sysfs" if EXPERT
2035 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2036 That memory map is required by the 2nd kernel to set up EFI virtual
2037 mappings after kexec, but can also be used for debugging purposes.
2039 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2041 source "kernel/Kconfig.hz"
2044 bool "kexec system call"
2047 kexec is a system call that implements the ability to shutdown your
2048 current kernel, and to start another kernel. It is like a reboot
2049 but it is independent of the system firmware. And like a reboot
2050 you can start any kernel with it, not just Linux.
2052 The name comes from the similarity to the exec system call.
2054 It is an ongoing process to be certain the hardware in a machine
2055 is properly shutdown, so do not be surprised if this code does not
2056 initially work for you. As of this writing the exact hardware
2057 interface is strongly in flux, so no good recommendation can be
2061 bool "kexec file based system call"
2063 select HAVE_IMA_KEXEC if IMA
2066 depends on CRYPTO_SHA256=y
2068 This is new version of kexec system call. This system call is
2069 file based and takes file descriptors as system call argument
2070 for kernel and initramfs as opposed to list of segments as
2071 accepted by previous system call.
2073 config ARCH_HAS_KEXEC_PURGATORY
2077 bool "Verify kernel signature during kexec_file_load() syscall"
2078 depends on KEXEC_FILE
2081 This option makes the kexec_file_load() syscall check for a valid
2082 signature of the kernel image. The image can still be loaded without
2083 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2084 there's a signature that we can check, then it must be valid.
2086 In addition to this option, you need to enable signature
2087 verification for the corresponding kernel image type being
2088 loaded in order for this to work.
2090 config KEXEC_SIG_FORCE
2091 bool "Require a valid signature in kexec_file_load() syscall"
2092 depends on KEXEC_SIG
2094 This option makes kernel signature verification mandatory for
2095 the kexec_file_load() syscall.
2097 config KEXEC_BZIMAGE_VERIFY_SIG
2098 bool "Enable bzImage signature verification support"
2099 depends on KEXEC_SIG
2100 depends on SIGNED_PE_FILE_VERIFICATION
2101 select SYSTEM_TRUSTED_KEYRING
2103 Enable bzImage signature verification support.
2106 bool "kernel crash dumps"
2107 depends on X86_64 || (X86_32 && HIGHMEM)
2109 Generate crash dump after being started by kexec.
2110 This should be normally only set in special crash dump kernels
2111 which are loaded in the main kernel with kexec-tools into
2112 a specially reserved region and then later executed after
2113 a crash by kdump/kexec. The crash dump kernel must be compiled
2114 to a memory address not used by the main kernel or BIOS using
2115 PHYSICAL_START, or it must be built as a relocatable image
2116 (CONFIG_RELOCATABLE=y).
2117 For more details see Documentation/admin-guide/kdump/kdump.rst
2121 depends on KEXEC && HIBERNATION
2123 Jump between original kernel and kexeced kernel and invoke
2124 code in physical address mode via KEXEC
2126 config PHYSICAL_START
2127 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2130 This gives the physical address where the kernel is loaded.
2132 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2133 bzImage will decompress itself to above physical address and
2134 run from there. Otherwise, bzImage will run from the address where
2135 it has been loaded by the boot loader and will ignore above physical
2138 In normal kdump cases one does not have to set/change this option
2139 as now bzImage can be compiled as a completely relocatable image
2140 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2141 address. This option is mainly useful for the folks who don't want
2142 to use a bzImage for capturing the crash dump and want to use a
2143 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2144 to be specifically compiled to run from a specific memory area
2145 (normally a reserved region) and this option comes handy.
2147 So if you are using bzImage for capturing the crash dump,
2148 leave the value here unchanged to 0x1000000 and set
2149 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2150 for capturing the crash dump change this value to start of
2151 the reserved region. In other words, it can be set based on
2152 the "X" value as specified in the "crashkernel=YM@XM"
2153 command line boot parameter passed to the panic-ed
2154 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2155 for more details about crash dumps.
2157 Usage of bzImage for capturing the crash dump is recommended as
2158 one does not have to build two kernels. Same kernel can be used
2159 as production kernel and capture kernel. Above option should have
2160 gone away after relocatable bzImage support is introduced. But it
2161 is present because there are users out there who continue to use
2162 vmlinux for dump capture. This option should go away down the
2165 Don't change this unless you know what you are doing.
2168 bool "Build a relocatable kernel"
2171 This builds a kernel image that retains relocation information
2172 so it can be loaded someplace besides the default 1MB.
2173 The relocations tend to make the kernel binary about 10% larger,
2174 but are discarded at runtime.
2176 One use is for the kexec on panic case where the recovery kernel
2177 must live at a different physical address than the primary
2180 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2181 it has been loaded at and the compile time physical address
2182 (CONFIG_PHYSICAL_START) is used as the minimum location.
2184 config RANDOMIZE_BASE
2185 bool "Randomize the address of the kernel image (KASLR)"
2186 depends on RELOCATABLE
2189 In support of Kernel Address Space Layout Randomization (KASLR),
2190 this randomizes the physical address at which the kernel image
2191 is decompressed and the virtual address where the kernel
2192 image is mapped, as a security feature that deters exploit
2193 attempts relying on knowledge of the location of kernel
2196 On 64-bit, the kernel physical and virtual addresses are
2197 randomized separately. The physical address will be anywhere
2198 between 16MB and the top of physical memory (up to 64TB). The
2199 virtual address will be randomized from 16MB up to 1GB (9 bits
2200 of entropy). Note that this also reduces the memory space
2201 available to kernel modules from 1.5GB to 1GB.
2203 On 32-bit, the kernel physical and virtual addresses are
2204 randomized together. They will be randomized from 16MB up to
2205 512MB (8 bits of entropy).
2207 Entropy is generated using the RDRAND instruction if it is
2208 supported. If RDTSC is supported, its value is mixed into
2209 the entropy pool as well. If neither RDRAND nor RDTSC are
2210 supported, then entropy is read from the i8254 timer. The
2211 usable entropy is limited by the kernel being built using
2212 2GB addressing, and that PHYSICAL_ALIGN must be at a
2213 minimum of 2MB. As a result, only 10 bits of entropy are
2214 theoretically possible, but the implementations are further
2215 limited due to memory layouts.
2219 # Relocation on x86 needs some additional build support
2220 config X86_NEED_RELOCS
2222 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2224 config PHYSICAL_ALIGN
2225 hex "Alignment value to which kernel should be aligned"
2227 range 0x2000 0x1000000 if X86_32
2228 range 0x200000 0x1000000 if X86_64
2230 This value puts the alignment restrictions on physical address
2231 where kernel is loaded and run from. Kernel is compiled for an
2232 address which meets above alignment restriction.
2234 If bootloader loads the kernel at a non-aligned address and
2235 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2236 address aligned to above value and run from there.
2238 If bootloader loads the kernel at a non-aligned address and
2239 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2240 load address and decompress itself to the address it has been
2241 compiled for and run from there. The address for which kernel is
2242 compiled already meets above alignment restrictions. Hence the
2243 end result is that kernel runs from a physical address meeting
2244 above alignment restrictions.
2246 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2247 this value must be a multiple of 0x200000.
2249 Don't change this unless you know what you are doing.
2251 config DYNAMIC_MEMORY_LAYOUT
2254 This option makes base addresses of vmalloc and vmemmap as well as
2255 __PAGE_OFFSET movable during boot.
2257 config RANDOMIZE_MEMORY
2258 bool "Randomize the kernel memory sections"
2260 depends on RANDOMIZE_BASE
2261 select DYNAMIC_MEMORY_LAYOUT
2262 default RANDOMIZE_BASE
2264 Randomizes the base virtual address of kernel memory sections
2265 (physical memory mapping, vmalloc & vmemmap). This security feature
2266 makes exploits relying on predictable memory locations less reliable.
2268 The order of allocations remains unchanged. Entropy is generated in
2269 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2270 configuration have in average 30,000 different possible virtual
2271 addresses for each memory section.
2275 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2276 hex "Physical memory mapping padding" if EXPERT
2277 depends on RANDOMIZE_MEMORY
2278 default "0xa" if MEMORY_HOTPLUG
2280 range 0x1 0x40 if MEMORY_HOTPLUG
2283 Define the padding in terabytes added to the existing physical
2284 memory size during kernel memory randomization. It is useful
2285 for memory hotplug support but reduces the entropy available for
2286 address randomization.
2288 If unsure, leave at the default value.
2290 config ADDRESS_MASKING
2291 bool "Linear Address Masking support"
2294 Linear Address Masking (LAM) modifies the checking that is applied
2295 to 64-bit linear addresses, allowing software to use of the
2296 untranslated address bits for metadata.
2298 The capability can be used for efficient address sanitizers (ASAN)
2299 implementation and for optimizations in JITs.
2307 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2308 depends on COMPAT_32
2310 Certain buggy versions of glibc will crash if they are
2311 presented with a 32-bit vDSO that is not mapped at the address
2312 indicated in its segment table.
2314 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2315 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2316 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2317 the only released version with the bug, but OpenSUSE 9
2318 contains a buggy "glibc 2.3.2".
2320 The symptom of the bug is that everything crashes on startup, saying:
2321 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2323 Saying Y here changes the default value of the vdso32 boot
2324 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2325 This works around the glibc bug but hurts performance.
2327 If unsure, say N: if you are compiling your own kernel, you
2328 are unlikely to be using a buggy version of glibc.
2331 prompt "vsyscall table for legacy applications"
2333 default LEGACY_VSYSCALL_XONLY
2335 Legacy user code that does not know how to find the vDSO expects
2336 to be able to issue three syscalls by calling fixed addresses in
2337 kernel space. Since this location is not randomized with ASLR,
2338 it can be used to assist security vulnerability exploitation.
2340 This setting can be changed at boot time via the kernel command
2341 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2342 is deprecated and can only be enabled using the kernel command
2345 On a system with recent enough glibc (2.14 or newer) and no
2346 static binaries, you can say None without a performance penalty
2347 to improve security.
2349 If unsure, select "Emulate execution only".
2351 config LEGACY_VSYSCALL_XONLY
2352 bool "Emulate execution only"
2354 The kernel traps and emulates calls into the fixed vsyscall
2355 address mapping and does not allow reads. This
2356 configuration is recommended when userspace might use the
2357 legacy vsyscall area but support for legacy binary
2358 instrumentation of legacy code is not needed. It mitigates
2359 certain uses of the vsyscall area as an ASLR-bypassing
2362 config LEGACY_VSYSCALL_NONE
2365 There will be no vsyscall mapping at all. This will
2366 eliminate any risk of ASLR bypass due to the vsyscall
2367 fixed address mapping. Attempts to use the vsyscalls
2368 will be reported to dmesg, so that either old or
2369 malicious userspace programs can be identified.
2374 bool "Built-in kernel command line"
2376 Allow for specifying boot arguments to the kernel at
2377 build time. On some systems (e.g. embedded ones), it is
2378 necessary or convenient to provide some or all of the
2379 kernel boot arguments with the kernel itself (that is,
2380 to not rely on the boot loader to provide them.)
2382 To compile command line arguments into the kernel,
2383 set this option to 'Y', then fill in the
2384 boot arguments in CONFIG_CMDLINE.
2386 Systems with fully functional boot loaders (i.e. non-embedded)
2387 should leave this option set to 'N'.
2390 string "Built-in kernel command string"
2391 depends on CMDLINE_BOOL
2394 Enter arguments here that should be compiled into the kernel
2395 image and used at boot time. If the boot loader provides a
2396 command line at boot time, it is appended to this string to
2397 form the full kernel command line, when the system boots.
2399 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2400 change this behavior.
2402 In most cases, the command line (whether built-in or provided
2403 by the boot loader) should specify the device for the root
2406 config CMDLINE_OVERRIDE
2407 bool "Built-in command line overrides boot loader arguments"
2408 depends on CMDLINE_BOOL && CMDLINE != ""
2410 Set this option to 'Y' to have the kernel ignore the boot loader
2411 command line, and use ONLY the built-in command line.
2413 This is used to work around broken boot loaders. This should
2414 be set to 'N' under normal conditions.
2416 config MODIFY_LDT_SYSCALL
2417 bool "Enable the LDT (local descriptor table)" if EXPERT
2420 Linux can allow user programs to install a per-process x86
2421 Local Descriptor Table (LDT) using the modify_ldt(2) system
2422 call. This is required to run 16-bit or segmented code such as
2423 DOSEMU or some Wine programs. It is also used by some very old
2424 threading libraries.
2426 Enabling this feature adds a small amount of overhead to
2427 context switches and increases the low-level kernel attack
2428 surface. Disabling it removes the modify_ldt(2) system call.
2430 Saying 'N' here may make sense for embedded or server kernels.
2432 config STRICT_SIGALTSTACK_SIZE
2433 bool "Enforce strict size checking for sigaltstack"
2434 depends on DYNAMIC_SIGFRAME
2436 For historical reasons MINSIGSTKSZ is a constant which became
2437 already too small with AVX512 support. Add a mechanism to
2438 enforce strict checking of the sigaltstack size against the
2439 real size of the FPU frame. This option enables the check
2440 by default. It can also be controlled via the kernel command
2441 line option 'strict_sas_size' independent of this config
2442 switch. Enabling it might break existing applications which
2443 allocate a too small sigaltstack but 'work' because they
2444 never get a signal delivered.
2446 Say 'N' unless you want to really enforce this check.
2448 source "kernel/livepatch/Kconfig"
2453 def_bool $(cc-option,-mharden-sls=all)
2455 config CC_HAS_RETURN_THUNK
2456 def_bool $(cc-option,-mfunction-return=thunk-extern)
2458 config CC_HAS_ENTRY_PADDING
2459 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2461 config FUNCTION_PADDING_CFI
2463 default 59 if FUNCTION_ALIGNMENT_64B
2464 default 27 if FUNCTION_ALIGNMENT_32B
2465 default 11 if FUNCTION_ALIGNMENT_16B
2466 default 3 if FUNCTION_ALIGNMENT_8B
2469 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2470 # except Kconfig can't do arithmetic :/
2471 config FUNCTION_PADDING_BYTES
2473 default FUNCTION_PADDING_CFI if CFI_CLANG
2474 default FUNCTION_ALIGNMENT
2478 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2479 select FUNCTION_ALIGNMENT_16B
2483 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2486 config HAVE_CALL_THUNKS
2488 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2494 config PREFIX_SYMBOLS
2496 depends on CALL_PADDING && !CFI_CLANG
2498 menuconfig SPECULATION_MITIGATIONS
2499 bool "Mitigations for speculative execution vulnerabilities"
2502 Say Y here to enable options which enable mitigations for
2503 speculative execution hardware vulnerabilities.
2505 If you say N, all mitigations will be disabled. You really
2506 should know what you are doing to say so.
2508 if SPECULATION_MITIGATIONS
2510 config PAGE_TABLE_ISOLATION
2511 bool "Remove the kernel mapping in user mode"
2513 depends on (X86_64 || X86_PAE)
2515 This feature reduces the number of hardware side channels by
2516 ensuring that the majority of kernel addresses are not mapped
2519 See Documentation/arch/x86/pti.rst for more details.
2522 bool "Avoid speculative indirect branches in kernel"
2523 select OBJTOOL if HAVE_OBJTOOL
2526 Compile kernel with the retpoline compiler options to guard against
2527 kernel-to-user data leaks by avoiding speculative indirect
2528 branches. Requires a compiler with -mindirect-branch=thunk-extern
2529 support for full protection. The kernel may run slower.
2532 bool "Enable return-thunks"
2533 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2534 select OBJTOOL if HAVE_OBJTOOL
2537 Compile the kernel with the return-thunks compiler option to guard
2538 against kernel-to-user data leaks by avoiding return speculation.
2539 Requires a compiler with -mfunction-return=thunk-extern
2540 support for full protection. The kernel may run slower.
2542 config CPU_UNRET_ENTRY
2543 bool "Enable UNRET on kernel entry"
2544 depends on CPU_SUP_AMD && RETHUNK && X86_64
2547 Compile the kernel with support for the retbleed=unret mitigation.
2549 config CALL_DEPTH_TRACKING
2550 bool "Mitigate RSB underflow with call depth tracking"
2551 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2552 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2556 Compile the kernel with call depth tracking to mitigate the Intel
2557 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2558 mitigation is off by default and needs to be enabled on the
2559 kernel command line via the retbleed=stuff option. For
2560 non-affected systems the overhead of this option is marginal as
2561 the call depth tracking is using run-time generated call thunks
2562 in a compiler generated padding area and call patching. This
2563 increases text size by ~5%. For non affected systems this space
2564 is unused. On affected SKL systems this results in a significant
2565 performance gain over the IBRS mitigation.
2567 config CALL_THUNKS_DEBUG
2568 bool "Enable call thunks and call depth tracking debugging"
2569 depends on CALL_DEPTH_TRACKING
2570 select FUNCTION_ALIGNMENT_32B
2573 Enable call/ret counters for imbalance detection and build in
2574 a noisy dmesg about callthunks generation and call patching for
2575 trouble shooting. The debug prints need to be enabled on the
2576 kernel command line with 'debug-callthunks'.
2577 Only enable this when you are debugging call thunks as this
2578 creates a noticeable runtime overhead. If unsure say N.
2580 config CPU_IBPB_ENTRY
2581 bool "Enable IBPB on kernel entry"
2582 depends on CPU_SUP_AMD && X86_64
2585 Compile the kernel with support for the retbleed=ibpb mitigation.
2587 config CPU_IBRS_ENTRY
2588 bool "Enable IBRS on kernel entry"
2589 depends on CPU_SUP_INTEL && X86_64
2592 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2593 This mitigates both spectre_v2 and retbleed at great cost to
2597 bool "Mitigate Straight-Line-Speculation"
2598 depends on CC_HAS_SLS && X86_64
2599 select OBJTOOL if HAVE_OBJTOOL
2602 Compile the kernel with straight-line-speculation options to guard
2603 against straight line speculation. The kernel image might be slightly
2608 config ARCH_HAS_ADD_PAGES
2610 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2612 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2615 menu "Power management and ACPI options"
2617 config ARCH_HIBERNATION_HEADER
2619 depends on HIBERNATION
2621 source "kernel/power/Kconfig"
2623 source "drivers/acpi/Kconfig"
2630 tristate "APM (Advanced Power Management) BIOS support"
2631 depends on X86_32 && PM_SLEEP
2633 APM is a BIOS specification for saving power using several different
2634 techniques. This is mostly useful for battery powered laptops with
2635 APM compliant BIOSes. If you say Y here, the system time will be
2636 reset after a RESUME operation, the /proc/apm device will provide
2637 battery status information, and user-space programs will receive
2638 notification of APM "events" (e.g. battery status change).
2640 If you select "Y" here, you can disable actual use of the APM
2641 BIOS by passing the "apm=off" option to the kernel at boot time.
2643 Note that the APM support is almost completely disabled for
2644 machines with more than one CPU.
2646 In order to use APM, you will need supporting software. For location
2647 and more information, read <file:Documentation/power/apm-acpi.rst>
2648 and the Battery Powered Linux mini-HOWTO, available from
2649 <http://www.tldp.org/docs.html#howto>.
2651 This driver does not spin down disk drives (see the hdparm(8)
2652 manpage ("man 8 hdparm") for that), and it doesn't turn off
2653 VESA-compliant "green" monitors.
2655 This driver does not support the TI 4000M TravelMate and the ACER
2656 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2657 desktop machines also don't have compliant BIOSes, and this driver
2658 may cause those machines to panic during the boot phase.
2660 Generally, if you don't have a battery in your machine, there isn't
2661 much point in using this driver and you should say N. If you get
2662 random kernel OOPSes or reboots that don't seem to be related to
2663 anything, try disabling/enabling this option (or disabling/enabling
2666 Some other things you should try when experiencing seemingly random,
2669 1) make sure that you have enough swap space and that it is
2671 2) pass the "idle=poll" option to the kernel
2672 3) switch on floating point emulation in the kernel and pass
2673 the "no387" option to the kernel
2674 4) pass the "floppy=nodma" option to the kernel
2675 5) pass the "mem=4M" option to the kernel (thereby disabling
2676 all but the first 4 MB of RAM)
2677 6) make sure that the CPU is not over clocked.
2678 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2679 8) disable the cache from your BIOS settings
2680 9) install a fan for the video card or exchange video RAM
2681 10) install a better fan for the CPU
2682 11) exchange RAM chips
2683 12) exchange the motherboard.
2685 To compile this driver as a module, choose M here: the
2686 module will be called apm.
2690 config APM_IGNORE_USER_SUSPEND
2691 bool "Ignore USER SUSPEND"
2693 This option will ignore USER SUSPEND requests. On machines with a
2694 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2695 series notebooks, it is necessary to say Y because of a BIOS bug.
2697 config APM_DO_ENABLE
2698 bool "Enable PM at boot time"
2700 Enable APM features at boot time. From page 36 of the APM BIOS
2701 specification: "When disabled, the APM BIOS does not automatically
2702 power manage devices, enter the Standby State, enter the Suspend
2703 State, or take power saving steps in response to CPU Idle calls."
2704 This driver will make CPU Idle calls when Linux is idle (unless this
2705 feature is turned off -- see "Do CPU IDLE calls", below). This
2706 should always save battery power, but more complicated APM features
2707 will be dependent on your BIOS implementation. You may need to turn
2708 this option off if your computer hangs at boot time when using APM
2709 support, or if it beeps continuously instead of suspending. Turn
2710 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2711 T400CDT. This is off by default since most machines do fine without
2716 bool "Make CPU Idle calls when idle"
2718 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2719 On some machines, this can activate improved power savings, such as
2720 a slowed CPU clock rate, when the machine is idle. These idle calls
2721 are made after the idle loop has run for some length of time (e.g.,
2722 333 mS). On some machines, this will cause a hang at boot time or
2723 whenever the CPU becomes idle. (On machines with more than one CPU,
2724 this option does nothing.)
2726 config APM_DISPLAY_BLANK
2727 bool "Enable console blanking using APM"
2729 Enable console blanking using the APM. Some laptops can use this to
2730 turn off the LCD backlight when the screen blanker of the Linux
2731 virtual console blanks the screen. Note that this is only used by
2732 the virtual console screen blanker, and won't turn off the backlight
2733 when using the X Window system. This also doesn't have anything to
2734 do with your VESA-compliant power-saving monitor. Further, this
2735 option doesn't work for all laptops -- it might not turn off your
2736 backlight at all, or it might print a lot of errors to the console,
2737 especially if you are using gpm.
2739 config APM_ALLOW_INTS
2740 bool "Allow interrupts during APM BIOS calls"
2742 Normally we disable external interrupts while we are making calls to
2743 the APM BIOS as a measure to lessen the effects of a badly behaving
2744 BIOS implementation. The BIOS should reenable interrupts if it
2745 needs to. Unfortunately, some BIOSes do not -- especially those in
2746 many of the newer IBM Thinkpads. If you experience hangs when you
2747 suspend, try setting this to Y. Otherwise, say N.
2751 source "drivers/cpufreq/Kconfig"
2753 source "drivers/cpuidle/Kconfig"
2755 source "drivers/idle/Kconfig"
2759 menu "Bus options (PCI etc.)"
2762 prompt "PCI access mode"
2763 depends on X86_32 && PCI
2766 On PCI systems, the BIOS can be used to detect the PCI devices and
2767 determine their configuration. However, some old PCI motherboards
2768 have BIOS bugs and may crash if this is done. Also, some embedded
2769 PCI-based systems don't have any BIOS at all. Linux can also try to
2770 detect the PCI hardware directly without using the BIOS.
2772 With this option, you can specify how Linux should detect the
2773 PCI devices. If you choose "BIOS", the BIOS will be used,
2774 if you choose "Direct", the BIOS won't be used, and if you
2775 choose "MMConfig", then PCI Express MMCONFIG will be used.
2776 If you choose "Any", the kernel will try MMCONFIG, then the
2777 direct access method and falls back to the BIOS if that doesn't
2778 work. If unsure, go with the default, which is "Any".
2783 config PCI_GOMMCONFIG
2800 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2802 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2805 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2808 bool "Support mmconfig PCI config space access" if X86_64
2810 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2811 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2815 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2819 depends on PCI && XEN
2821 config MMCONF_FAM10H
2823 depends on X86_64 && PCI_MMCONFIG && ACPI
2825 config PCI_CNB20LE_QUIRK
2826 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2829 Read the PCI windows out of the CNB20LE host bridge. This allows
2830 PCI hotplug to work on systems with the CNB20LE chipset which do
2833 There's no public spec for this chipset, and this functionality
2834 is known to be incomplete.
2836 You should say N unless you know you need this.
2839 bool "ISA bus support on modern systems" if EXPERT
2841 Expose ISA bus device drivers and options available for selection and
2842 configuration. Enable this option if your target machine has an ISA
2843 bus. ISA is an older system, displaced by PCI and newer bus
2844 architectures -- if your target machine is modern, it probably does
2845 not have an ISA bus.
2849 # x86_64 have no ISA slots, but can have ISA-style DMA.
2851 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2854 Enables ISA-style DMA support for devices requiring such controllers.
2862 Find out whether you have ISA slots on your motherboard. ISA is the
2863 name of a bus system, i.e. the way the CPU talks to the other stuff
2864 inside your box. Other bus systems are PCI, EISA, MicroChannel
2865 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2866 newer boards don't support it. If you have ISA, say Y, otherwise N.
2869 tristate "NatSemi SCx200 support"
2871 This provides basic support for National Semiconductor's
2872 (now AMD's) Geode processors. The driver probes for the
2873 PCI-IDs of several on-chip devices, so its a good dependency
2874 for other scx200_* drivers.
2876 If compiled as a module, the driver is named scx200.
2878 config SCx200HR_TIMER
2879 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2883 This driver provides a clocksource built upon the on-chip
2884 27MHz high-resolution timer. Its also a workaround for
2885 NSC Geode SC-1100's buggy TSC, which loses time when the
2886 processor goes idle (as is done by the scheduler). The
2887 other workaround is idle=poll boot option.
2890 bool "One Laptop Per Child support"
2898 Add support for detecting the unique features of the OLPC
2902 bool "OLPC XO-1 Power Management"
2903 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2905 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2908 bool "OLPC XO-1 Real Time Clock"
2909 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2911 Add support for the XO-1 real time clock, which can be used as a
2912 programmable wakeup source.
2915 bool "OLPC XO-1 SCI extras"
2916 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2920 Add support for SCI-based features of the OLPC XO-1 laptop:
2921 - EC-driven system wakeups
2925 - AC adapter status updates
2926 - Battery status updates
2928 config OLPC_XO15_SCI
2929 bool "OLPC XO-1.5 SCI extras"
2930 depends on OLPC && ACPI
2933 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2934 - EC-driven system wakeups
2935 - AC adapter status updates
2936 - Battery status updates
2939 bool "PCEngines ALIX System Support (LED setup)"
2942 This option enables system support for the PCEngines ALIX.
2943 At present this just sets up LEDs for GPIO control on
2944 ALIX2/3/6 boards. However, other system specific setup should
2947 Note: You must still enable the drivers for GPIO and LED support
2948 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2950 Note: You have to set alix.force=1 for boards with Award BIOS.
2953 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2956 This option enables system support for the Soekris Engineering net5501.
2959 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2963 This option enables system support for the Traverse Technologies GEOS.
2966 bool "Technologic Systems TS-5500 platform support"
2968 select CHECK_SIGNATURE
2972 This option enables system support for the Technologic Systems TS-5500.
2978 depends on CPU_SUP_AMD && PCI
2982 menu "Binary Emulations"
2984 config IA32_EMULATION
2985 bool "IA32 Emulation"
2987 select ARCH_WANT_OLD_COMPAT_IPC
2989 select COMPAT_OLD_SIGACTION
2991 Include code to run legacy 32-bit programs under a
2992 64-bit kernel. You should likely turn this on, unless you're
2993 100% sure that you don't have any 32-bit programs left.
2996 bool "x32 ABI for 64-bit mode"
2998 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2999 # compressed debug sections to x86_x32 properly:
3000 # https://github.com/ClangBuiltLinux/linux/issues/514
3001 # https://github.com/ClangBuiltLinux/linux/issues/1141
3002 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3004 Include code to run binaries for the x32 native 32-bit ABI
3005 for 64-bit processors. An x32 process gets access to the
3006 full 64-bit register file and wide data path while leaving
3007 pointers at 32 bits for smaller memory footprint.
3011 depends on IA32_EMULATION || X86_32
3013 select OLD_SIGSUSPEND3
3017 depends on IA32_EMULATION || X86_X32_ABI
3019 config COMPAT_FOR_U64_ALIGNMENT
3025 config HAVE_ATOMIC_IOMAP
3029 source "arch/x86/kvm/Kconfig"
3031 source "arch/x86/Kconfig.assembler"