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_CURRENT_STACK_POINTER
75 select ARCH_HAS_DEBUG_VIRTUAL
76 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
77 select ARCH_HAS_DEVMEM_IS_ALLOWED
78 select ARCH_HAS_EARLY_DEBUG if KGDB
79 select ARCH_HAS_ELF_RANDOMIZE
80 select ARCH_HAS_FAST_MULTIPLIER
81 select ARCH_HAS_FORTIFY_SOURCE
82 select ARCH_HAS_GCOV_PROFILE_ALL
83 select ARCH_HAS_KCOV if X86_64
84 select ARCH_HAS_MEM_ENCRYPT
85 select ARCH_HAS_MEMBARRIER_SYNC_CORE
86 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
87 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
88 select ARCH_HAS_PMEM_API if X86_64
89 select ARCH_HAS_PTE_DEVMAP if X86_64
90 select ARCH_HAS_PTE_SPECIAL
91 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
92 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
93 select ARCH_HAS_COPY_MC if X86_64
94 select ARCH_HAS_SET_MEMORY
95 select ARCH_HAS_SET_DIRECT_MAP
96 select ARCH_HAS_STRICT_KERNEL_RWX
97 select ARCH_HAS_STRICT_MODULE_RWX
98 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
99 select ARCH_HAS_SYSCALL_WRAPPER
100 select ARCH_HAS_UBSAN_SANITIZE_ALL
101 select ARCH_HAS_DEBUG_WX
102 select ARCH_HAS_ZONE_DMA_SET if EXPERT
103 select ARCH_HAVE_NMI_SAFE_CMPXCHG
104 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
105 select ARCH_MIGHT_HAVE_PC_PARPORT
106 select ARCH_MIGHT_HAVE_PC_SERIO
107 select ARCH_STACKWALK
108 select ARCH_SUPPORTS_ACPI
109 select ARCH_SUPPORTS_ATOMIC_RMW
110 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
111 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
112 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
113 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
114 select ARCH_SUPPORTS_CFI_CLANG if X86_64
115 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
116 select ARCH_SUPPORTS_LTO_CLANG
117 select ARCH_SUPPORTS_LTO_CLANG_THIN
118 select ARCH_USE_BUILTIN_BSWAP
119 select ARCH_USE_MEMTEST
120 select ARCH_USE_QUEUED_RWLOCKS
121 select ARCH_USE_QUEUED_SPINLOCKS
122 select ARCH_USE_SYM_ANNOTATIONS
123 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
124 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
125 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
126 select ARCH_WANTS_NO_INSTR
127 select ARCH_WANT_GENERAL_HUGETLB
128 select ARCH_WANT_HUGE_PMD_SHARE
129 select ARCH_WANT_LD_ORPHAN_WARN
130 select ARCH_WANT_OPTIMIZE_VMEMMAP if X86_64
131 select ARCH_WANTS_THP_SWAP if X86_64
132 select ARCH_HAS_PARANOID_L1D_FLUSH
133 select BUILDTIME_TABLE_SORT
135 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
136 select CLOCKSOURCE_WATCHDOG
137 # Word-size accesses may read uninitialized data past the trailing \0
138 # in strings and cause false KMSAN reports.
139 select DCACHE_WORD_ACCESS if !KMSAN
140 select DYNAMIC_SIGFRAME
141 select EDAC_ATOMIC_SCRUB
143 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
144 select GENERIC_CLOCKEVENTS_MIN_ADJUST
145 select GENERIC_CMOS_UPDATE
146 select GENERIC_CPU_AUTOPROBE
147 select GENERIC_CPU_VULNERABILITIES
148 select GENERIC_EARLY_IOREMAP
151 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
152 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
153 select GENERIC_IRQ_MIGRATION if SMP
154 select GENERIC_IRQ_PROBE
155 select GENERIC_IRQ_RESERVATION_MODE
156 select GENERIC_IRQ_SHOW
157 select GENERIC_PENDING_IRQ if SMP
158 select GENERIC_PTDUMP
159 select GENERIC_SMP_IDLE_THREAD
160 select GENERIC_TIME_VSYSCALL
161 select GENERIC_GETTIMEOFDAY
162 select GENERIC_VDSO_TIME_NS
163 select GUP_GET_PXX_LOW_HIGH if X86_PAE
164 select HARDIRQS_SW_RESEND
165 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
167 select HAVE_ACPI_APEI if ACPI
168 select HAVE_ACPI_APEI_NMI if ACPI
169 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
170 select HAVE_ARCH_AUDITSYSCALL
171 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
172 select HAVE_ARCH_HUGE_VMALLOC if X86_64
173 select HAVE_ARCH_JUMP_LABEL
174 select HAVE_ARCH_JUMP_LABEL_RELATIVE
175 select HAVE_ARCH_KASAN if X86_64
176 select HAVE_ARCH_KASAN_VMALLOC if X86_64
177 select HAVE_ARCH_KFENCE
178 select HAVE_ARCH_KMSAN if X86_64
179 select HAVE_ARCH_KGDB
180 select HAVE_ARCH_MMAP_RND_BITS if MMU
181 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
182 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
183 select HAVE_ARCH_PREL32_RELOCATIONS
184 select HAVE_ARCH_SECCOMP_FILTER
185 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
186 select HAVE_ARCH_STACKLEAK
187 select HAVE_ARCH_TRACEHOOK
188 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
189 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
190 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
191 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
192 select HAVE_ARCH_VMAP_STACK if X86_64
193 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
194 select HAVE_ARCH_WITHIN_STACK_FRAMES
195 select HAVE_ASM_MODVERSIONS
196 select HAVE_CMPXCHG_DOUBLE
197 select HAVE_CMPXCHG_LOCAL
198 select HAVE_CONTEXT_TRACKING_USER if X86_64
199 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
200 select HAVE_C_RECORDMCOUNT
201 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
202 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
203 select HAVE_BUILDTIME_MCOUNT_SORT
204 select HAVE_DEBUG_KMEMLEAK
205 select HAVE_DMA_CONTIGUOUS
206 select HAVE_DYNAMIC_FTRACE
207 select HAVE_DYNAMIC_FTRACE_WITH_REGS
208 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
209 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
210 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
211 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
213 select HAVE_EFFICIENT_UNALIGNED_ACCESS
215 select HAVE_EXIT_THREAD
217 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
218 select HAVE_FTRACE_MCOUNT_RECORD
219 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
220 select HAVE_FUNCTION_TRACER
221 select HAVE_GCC_PLUGINS
222 select HAVE_HW_BREAKPOINT
223 select HAVE_IOREMAP_PROT
224 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
225 select HAVE_IRQ_TIME_ACCOUNTING
226 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
227 select HAVE_KERNEL_BZIP2
228 select HAVE_KERNEL_GZIP
229 select HAVE_KERNEL_LZ4
230 select HAVE_KERNEL_LZMA
231 select HAVE_KERNEL_LZO
232 select HAVE_KERNEL_XZ
233 select HAVE_KERNEL_ZSTD
235 select HAVE_KPROBES_ON_FTRACE
236 select HAVE_FUNCTION_ERROR_INJECTION
237 select HAVE_KRETPROBES
240 select HAVE_LIVEPATCH if X86_64
241 select HAVE_MIXED_BREAKPOINTS_REGS
242 select HAVE_MOD_ARCH_SPECIFIC
245 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
247 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
248 select HAVE_OBJTOOL if X86_64
249 select HAVE_OPTPROBES
250 select HAVE_PCSPKR_PLATFORM
251 select HAVE_PERF_EVENTS
252 select HAVE_PERF_EVENTS_NMI
253 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
255 select HAVE_PERF_REGS
256 select HAVE_PERF_USER_STACK_DUMP
257 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
258 select MMU_GATHER_MERGE_VMAS
259 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
260 select HAVE_REGS_AND_STACK_ACCESS_API
261 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
262 select HAVE_FUNCTION_ARG_ACCESS_API
263 select HAVE_SETUP_PER_CPU_AREA
264 select HAVE_SOFTIRQ_ON_OWN_STACK
265 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
266 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
267 select HAVE_STATIC_CALL
268 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
269 select HAVE_PREEMPT_DYNAMIC_CALL
271 select HAVE_RUST if X86_64
272 select HAVE_SYSCALL_TRACEPOINTS
273 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
274 select HAVE_UNSTABLE_SCHED_CLOCK
275 select HAVE_USER_RETURN_NOTIFIER
276 select HAVE_GENERIC_VDSO
277 select HOTPLUG_PARALLEL if SMP && X86_64
278 select HOTPLUG_SMT if SMP
279 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
280 select IRQ_FORCED_THREADING
281 select NEED_PER_CPU_EMBED_FIRST_CHUNK
282 select NEED_PER_CPU_PAGE_FIRST_CHUNK
283 select NEED_SG_DMA_LENGTH
284 select PCI_DOMAINS if PCI
285 select PCI_LOCKLESS_CONFIG if PCI
288 select RTC_MC146818_LIB
290 select SYSCTL_EXCEPTION_TRACE
291 select THREAD_INFO_IN_TASK
292 select TRACE_IRQFLAGS_SUPPORT
293 select TRACE_IRQFLAGS_NMI_SUPPORT
294 select USER_STACKTRACE_SUPPORT
295 select HAVE_ARCH_KCSAN if X86_64
296 select X86_FEATURE_NAMES if PROC_FS
297 select PROC_PID_ARCH_STATUS if PROC_FS
298 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
299 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
300 select FUNCTION_ALIGNMENT_4B
301 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
302 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
304 config INSTRUCTION_DECODER
306 depends on KPROBES || PERF_EVENTS || UPROBES
310 default "elf32-i386" if X86_32
311 default "elf64-x86-64" if X86_64
313 config LOCKDEP_SUPPORT
316 config STACKTRACE_SUPPORT
322 config ARCH_MMAP_RND_BITS_MIN
326 config ARCH_MMAP_RND_BITS_MAX
330 config ARCH_MMAP_RND_COMPAT_BITS_MIN
333 config ARCH_MMAP_RND_COMPAT_BITS_MAX
339 config GENERIC_ISA_DMA
341 depends on ISA_DMA_API
345 default y if KMSAN || KASAN
350 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
352 config GENERIC_BUG_RELATIVE_POINTERS
355 config ARCH_MAY_HAVE_PC_FDC
357 depends on ISA_DMA_API
359 config GENERIC_CALIBRATE_DELAY
362 config ARCH_HAS_CPU_RELAX
365 config ARCH_HIBERNATION_POSSIBLE
368 config ARCH_SUSPEND_POSSIBLE
374 config KASAN_SHADOW_OFFSET
377 default 0xdffffc0000000000
379 config HAVE_INTEL_TXT
381 depends on INTEL_IOMMU && ACPI
385 depends on X86_32 && SMP
389 depends on X86_64 && SMP
391 config ARCH_SUPPORTS_UPROBES
394 config FIX_EARLYCON_MEM
397 config DYNAMIC_PHYSICAL_MASK
400 config PGTABLE_LEVELS
402 default 5 if X86_5LEVEL
407 config CC_HAS_SANE_STACKPROTECTOR
409 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
410 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
412 We have to make sure stack protector is unconditionally disabled if
413 the compiler produces broken code or if it does not let us control
414 the segment on 32-bit kernels.
416 menu "Processor type and features"
419 bool "Symmetric multi-processing support"
421 This enables support for systems with more than one CPU. If you have
422 a system with only one CPU, say N. If you have a system with more
425 If you say N here, the kernel will run on uni- and multiprocessor
426 machines, but will use only one CPU of a multiprocessor machine. If
427 you say Y here, the kernel will run on many, but not all,
428 uniprocessor machines. On a uniprocessor machine, the kernel
429 will run faster if you say N here.
431 Note that if you say Y here and choose architecture "586" or
432 "Pentium" under "Processor family", the kernel will not work on 486
433 architectures. Similarly, multiprocessor kernels for the "PPro"
434 architecture may not work on all Pentium based boards.
436 People using multiprocessor machines who say Y here should also say
437 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
438 Management" code will be disabled if you say Y here.
440 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
441 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
442 <http://www.tldp.org/docs.html#howto>.
444 If you don't know what to do here, say N.
446 config X86_FEATURE_NAMES
447 bool "Processor feature human-readable names" if EMBEDDED
450 This option compiles in a table of x86 feature bits and corresponding
451 names. This is required to support /proc/cpuinfo and a few kernel
452 messages. You can disable this to save space, at the expense of
453 making those few kernel messages show numeric feature bits instead.
458 bool "Support x2apic"
459 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
461 This enables x2apic support on CPUs that have this feature.
463 This allows 32-bit apic IDs (so it can support very large systems),
464 and accesses the local apic via MSRs not via mmio.
466 Some Intel systems circa 2022 and later are locked into x2APIC mode
467 and can not fall back to the legacy APIC modes if SGX or TDX are
468 enabled in the BIOS. They will boot with very reduced functionality
469 without enabling this option.
471 If you don't know what to do here, say N.
474 bool "Enable MPS table" if ACPI
476 depends on X86_LOCAL_APIC
478 For old smp systems that do not have proper acpi support. Newer systems
479 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
483 depends on X86_GOLDFISH
485 config X86_CPU_RESCTRL
486 bool "x86 CPU resource control support"
487 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
489 select PROC_CPU_RESCTRL if PROC_FS
491 Enable x86 CPU resource control support.
493 Provide support for the allocation and monitoring of system resources
496 Intel calls this Intel Resource Director Technology
497 (Intel(R) RDT). More information about RDT can be found in the
498 Intel x86 Architecture Software Developer Manual.
500 AMD calls this AMD Platform Quality of Service (AMD QoS).
501 More information about AMD QoS can be found in the AMD64 Technology
502 Platform Quality of Service Extensions manual.
508 bool "Support for big SMP systems with more than 8 CPUs"
511 This option is needed for the systems that have more than 8 CPUs.
513 config X86_EXTENDED_PLATFORM
514 bool "Support for extended (non-PC) x86 platforms"
517 If you disable this option then the kernel will only support
518 standard PC platforms. (which covers the vast majority of
521 If you enable this option then you'll be able to select support
522 for the following (non-PC) 32 bit x86 platforms:
523 Goldfish (Android emulator)
526 SGI 320/540 (Visual Workstation)
527 STA2X11-based (e.g. Northville)
528 Moorestown MID devices
530 If you have one of these systems, or if you want to build a
531 generic distribution kernel, say Y here - otherwise say N.
535 config X86_EXTENDED_PLATFORM
536 bool "Support for extended (non-PC) x86 platforms"
539 If you disable this option then the kernel will only support
540 standard PC platforms. (which covers the vast majority of
543 If you enable this option then you'll be able to select support
544 for the following (non-PC) 64 bit x86 platforms:
549 If you have one of these systems, or if you want to build a
550 generic distribution kernel, say Y here - otherwise say N.
552 # This is an alphabetically sorted list of 64 bit extended platforms
553 # Please maintain the alphabetic order if and when there are additions
555 bool "Numascale NumaChip"
557 depends on X86_EXTENDED_PLATFORM
560 depends on X86_X2APIC
561 depends on PCI_MMCONFIG
563 Adds support for Numascale NumaChip large-SMP systems. Needed to
564 enable more than ~168 cores.
565 If you don't have one of these, you should say N here.
569 select HYPERVISOR_GUEST
571 depends on X86_64 && PCI
572 depends on X86_EXTENDED_PLATFORM
575 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
576 supposed to run on these EM64T-based machines. Only choose this option
577 if you have one of these machines.
580 bool "SGI Ultraviolet"
582 depends on X86_EXTENDED_PLATFORM
585 depends on KEXEC_CORE
586 depends on X86_X2APIC
589 This option is needed in order to support SGI Ultraviolet systems.
590 If you don't have one of these, you should say N here.
592 # Following is an alphabetically sorted list of 32 bit extended platforms
593 # Please maintain the alphabetic order if and when there are additions
596 bool "Goldfish (Virtual Platform)"
597 depends on X86_EXTENDED_PLATFORM
599 Enable support for the Goldfish virtual platform used primarily
600 for Android development. Unless you are building for the Android
601 Goldfish emulator say N here.
604 bool "CE4100 TV platform"
606 depends on PCI_GODIRECT
607 depends on X86_IO_APIC
609 depends on X86_EXTENDED_PLATFORM
610 select X86_REBOOTFIXUPS
612 select OF_EARLY_FLATTREE
614 Select for the Intel CE media processor (CE4100) SOC.
615 This option compiles in support for the CE4100 SOC for settop
616 boxes and media devices.
619 bool "Intel MID platform support"
620 depends on X86_EXTENDED_PLATFORM
621 depends on X86_PLATFORM_DEVICES
623 depends on X86_64 || (PCI_GOANY && X86_32)
624 depends on X86_IO_APIC
629 Select to build a kernel capable of supporting Intel MID (Mobile
630 Internet Device) platform systems which do not have the PCI legacy
631 interfaces. If you are building for a PC class system say N here.
633 Intel MID platforms are based on an Intel processor and chipset which
634 consume less power than most of the x86 derivatives.
636 config X86_INTEL_QUARK
637 bool "Intel Quark platform support"
639 depends on X86_EXTENDED_PLATFORM
640 depends on X86_PLATFORM_DEVICES
644 depends on X86_IO_APIC
649 Select to include support for Quark X1000 SoC.
650 Say Y here if you have a Quark based system such as the Arduino
651 compatible Intel Galileo.
653 config X86_INTEL_LPSS
654 bool "Intel Low Power Subsystem Support"
655 depends on X86 && ACPI && PCI
660 Select to build support for Intel Low Power Subsystem such as
661 found on Intel Lynxpoint PCH. Selecting this option enables
662 things like clock tree (common clock framework) and pincontrol
663 which are needed by the LPSS peripheral drivers.
665 config X86_AMD_PLATFORM_DEVICE
666 bool "AMD ACPI2Platform devices support"
671 Select to interpret AMD specific ACPI device to platform device
672 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
673 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
674 implemented under PINCTRL subsystem.
677 tristate "Intel SoC IOSF Sideband support for SoC platforms"
680 This option enables sideband register access support for Intel SoC
681 platforms. On these platforms the IOSF sideband is used in lieu of
682 MSR's for some register accesses, mostly but not limited to thermal
683 and power. Drivers may query the availability of this device to
684 determine if they need the sideband in order to work on these
685 platforms. The sideband is available on the following SoC products.
686 This list is not meant to be exclusive.
691 You should say Y if you are running a kernel on one of these SoC's.
693 config IOSF_MBI_DEBUG
694 bool "Enable IOSF sideband access through debugfs"
695 depends on IOSF_MBI && DEBUG_FS
697 Select this option to expose the IOSF sideband access registers (MCR,
698 MDR, MCRX) through debugfs to write and read register information from
699 different units on the SoC. This is most useful for obtaining device
700 state information for debug and analysis. As this is a general access
701 mechanism, users of this option would have specific knowledge of the
702 device they want to access.
704 If you don't require the option or are in doubt, say N.
707 bool "RDC R-321x SoC"
709 depends on X86_EXTENDED_PLATFORM
711 select X86_REBOOTFIXUPS
713 This option is needed for RDC R-321x system-on-chip, also known
715 If you don't have one of these chips, you should say N here.
717 config X86_32_NON_STANDARD
718 bool "Support non-standard 32-bit SMP architectures"
719 depends on X86_32 && SMP
720 depends on X86_EXTENDED_PLATFORM
722 This option compiles in the bigsmp and STA2X11 default
723 subarchitectures. It is intended for a generic binary
724 kernel. If you select them all, kernel will probe it one by
725 one and will fallback to default.
727 # Alphabetically sorted list of Non standard 32 bit platforms
729 config X86_SUPPORTS_MEMORY_FAILURE
731 # MCE code calls memory_failure():
733 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
734 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
735 depends on X86_64 || !SPARSEMEM
736 select ARCH_SUPPORTS_MEMORY_FAILURE
739 bool "STA2X11 Companion Chip Support"
740 depends on X86_32_NON_STANDARD && PCI
745 This adds support for boards based on the STA2X11 IO-Hub,
746 a.k.a. "ConneXt". The chip is used in place of the standard
747 PC chipset, so all "standard" peripherals are missing. If this
748 option is selected the kernel will still be able to boot on
749 standard PC machines.
752 tristate "Eurobraille/Iris poweroff module"
755 The Iris machines from EuroBraille do not have APM or ACPI support
756 to shut themselves down properly. A special I/O sequence is
757 needed to do so, which is what this module does at
760 This is only for Iris machines from EuroBraille.
764 config SCHED_OMIT_FRAME_POINTER
766 prompt "Single-depth WCHAN output"
769 Calculate simpler /proc/<PID>/wchan values. If this option
770 is disabled then wchan values will recurse back to the
771 caller function. This provides more accurate wchan values,
772 at the expense of slightly more scheduling overhead.
774 If in doubt, say "Y".
776 menuconfig HYPERVISOR_GUEST
777 bool "Linux guest support"
779 Say Y here to enable options for running Linux under various hyper-
780 visors. This option enables basic hypervisor detection and platform
783 If you say N, all options in this submenu will be skipped and
784 disabled, and Linux guest support won't be built in.
789 bool "Enable paravirtualization code"
790 depends on HAVE_STATIC_CALL
792 This changes the kernel so it can modify itself when it is run
793 under a hypervisor, potentially improving performance significantly
794 over full virtualization. However, when run without a hypervisor
795 the kernel is theoretically slower and slightly larger.
800 config PARAVIRT_DEBUG
801 bool "paravirt-ops debugging"
802 depends on PARAVIRT && DEBUG_KERNEL
804 Enable to debug paravirt_ops internals. Specifically, BUG if
805 a paravirt_op is missing when it is called.
807 config PARAVIRT_SPINLOCKS
808 bool "Paravirtualization layer for spinlocks"
809 depends on PARAVIRT && SMP
811 Paravirtualized spinlocks allow a pvops backend to replace the
812 spinlock implementation with something virtualization-friendly
813 (for example, block the virtual CPU rather than spinning).
815 It has a minimal impact on native kernels and gives a nice performance
816 benefit on paravirtualized KVM / Xen kernels.
818 If you are unsure how to answer this question, answer Y.
820 config X86_HV_CALLBACK_VECTOR
823 source "arch/x86/xen/Kconfig"
826 bool "KVM Guest support (including kvmclock)"
828 select PARAVIRT_CLOCK
829 select ARCH_CPUIDLE_HALTPOLL
830 select X86_HV_CALLBACK_VECTOR
833 This option enables various optimizations for running under the KVM
834 hypervisor. It includes a paravirtualized clock, so that instead
835 of relying on a PIT (or probably other) emulation by the
836 underlying device model, the host provides the guest with
837 timing infrastructure such as time of day, and system time
839 config ARCH_CPUIDLE_HALTPOLL
841 prompt "Disable host haltpoll when loading haltpoll driver"
843 If virtualized under KVM, disable host haltpoll.
846 bool "Support for running PVH guests"
848 This option enables the PVH entry point for guest virtual machines
849 as specified in the x86/HVM direct boot ABI.
851 config PARAVIRT_TIME_ACCOUNTING
852 bool "Paravirtual steal time accounting"
855 Select this option to enable fine granularity task steal time
856 accounting. Time spent executing other tasks in parallel with
857 the current vCPU is discounted from the vCPU power. To account for
858 that, there can be a small performance impact.
860 If in doubt, say N here.
862 config PARAVIRT_CLOCK
865 config JAILHOUSE_GUEST
866 bool "Jailhouse non-root cell support"
867 depends on X86_64 && PCI
870 This option allows to run Linux as guest in a Jailhouse non-root
871 cell. You can leave this option disabled if you only want to start
872 Jailhouse and run Linux afterwards in the root cell.
875 bool "ACRN Guest support"
877 select X86_HV_CALLBACK_VECTOR
879 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
880 a flexible, lightweight reference open-source hypervisor, built with
881 real-time and safety-criticality in mind. It is built for embedded
882 IOT with small footprint and real-time features. More details can be
883 found in https://projectacrn.org/.
885 config INTEL_TDX_GUEST
886 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
887 depends on X86_64 && CPU_SUP_INTEL
888 depends on X86_X2APIC
889 select ARCH_HAS_CC_PLATFORM
890 select X86_MEM_ENCRYPT
893 Support running as a guest under Intel TDX. Without this support,
894 the guest kernel can not boot or run under TDX.
895 TDX includes memory encryption and integrity capabilities
896 which protect the confidentiality and integrity of guest
897 memory contents and CPU state. TDX guests are protected from
898 some attacks from the VMM.
900 endif # HYPERVISOR_GUEST
902 source "arch/x86/Kconfig.cpu"
906 prompt "HPET Timer Support" if X86_32
908 Use the IA-PC HPET (High Precision Event Timer) to manage
909 time in preference to the PIT and RTC, if a HPET is
911 HPET is the next generation timer replacing legacy 8254s.
912 The HPET provides a stable time base on SMP
913 systems, unlike the TSC, but it is more expensive to access,
914 as it is off-chip. The interface used is documented
915 in the HPET spec, revision 1.
917 You can safely choose Y here. However, HPET will only be
918 activated if the platform and the BIOS support this feature.
919 Otherwise the 8254 will be used for timing services.
921 Choose N to continue using the legacy 8254 timer.
923 config HPET_EMULATE_RTC
925 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
927 # Mark as expert because too many people got it wrong.
928 # The code disables itself when not needed.
931 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
932 bool "Enable DMI scanning" if EXPERT
934 Enabled scanning of DMI to identify machine quirks. Say Y
935 here unless you have verified that your setup is not
936 affected by entries in the DMI blacklist. Required by PNP
940 bool "Old AMD GART IOMMU support"
944 depends on X86_64 && PCI && AMD_NB
946 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
947 GART based hardware IOMMUs.
949 The GART supports full DMA access for devices with 32-bit access
950 limitations, on systems with more than 3 GB. This is usually needed
951 for USB, sound, many IDE/SATA chipsets and some other devices.
953 Newer systems typically have a modern AMD IOMMU, supported via
954 the CONFIG_AMD_IOMMU=y config option.
956 In normal configurations this driver is only active when needed:
957 there's more than 3 GB of memory and the system contains a
958 32-bit limited device.
962 config BOOT_VESA_SUPPORT
965 If true, at least one selected framebuffer driver can take advantage
966 of VESA video modes set at an early boot stage via the vga= parameter.
969 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
970 depends on X86_64 && SMP && DEBUG_KERNEL
971 select CPUMASK_OFFSTACK
973 Enable maximum number of CPUS and NUMA Nodes for this architecture.
977 # The maximum number of CPUs supported:
979 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
980 # and which can be configured interactively in the
981 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
983 # The ranges are different on 32-bit and 64-bit kernels, depending on
984 # hardware capabilities and scalability features of the kernel.
986 # ( If MAXSMP is enabled we just use the highest possible value and disable
987 # interactive configuration. )
990 config NR_CPUS_RANGE_BEGIN
992 default NR_CPUS_RANGE_END if MAXSMP
996 config NR_CPUS_RANGE_END
999 default 64 if SMP && X86_BIGSMP
1000 default 8 if SMP && !X86_BIGSMP
1003 config NR_CPUS_RANGE_END
1006 default 8192 if SMP && CPUMASK_OFFSTACK
1007 default 512 if SMP && !CPUMASK_OFFSTACK
1010 config NR_CPUS_DEFAULT
1013 default 32 if X86_BIGSMP
1017 config NR_CPUS_DEFAULT
1020 default 8192 if MAXSMP
1025 int "Maximum number of CPUs" if SMP && !MAXSMP
1026 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1027 default NR_CPUS_DEFAULT
1029 This allows you to specify the maximum number of CPUs which this
1030 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1031 supported value is 8192, otherwise the maximum value is 512. The
1032 minimum value which makes sense is 2.
1034 This is purely to save memory: each supported CPU adds about 8KB
1035 to the kernel image.
1037 config SCHED_CLUSTER
1038 bool "Cluster scheduler support"
1042 Cluster scheduler support improves the CPU scheduler's decision
1043 making when dealing with machines that have clusters of CPUs.
1044 Cluster usually means a couple of CPUs which are placed closely
1045 by sharing mid-level caches, last-level cache tags or internal
1053 prompt "Multi-core scheduler support"
1056 Multi-core scheduler support improves the CPU scheduler's decision
1057 making when dealing with multi-core CPU chips at a cost of slightly
1058 increased overhead in some places. If unsure say N here.
1060 config SCHED_MC_PRIO
1061 bool "CPU core priorities scheduler support"
1062 depends on SCHED_MC && CPU_SUP_INTEL
1063 select X86_INTEL_PSTATE
1067 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1068 core ordering determined at manufacturing time, which allows
1069 certain cores to reach higher turbo frequencies (when running
1070 single threaded workloads) than others.
1072 Enabling this kernel feature teaches the scheduler about
1073 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1074 scheduler's CPU selection logic accordingly, so that higher
1075 overall system performance can be achieved.
1077 This feature will have no effect on CPUs without this feature.
1079 If unsure say Y here.
1083 depends on !SMP && X86_LOCAL_APIC
1086 bool "Local APIC support on uniprocessors" if !PCI_MSI
1088 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1090 A local APIC (Advanced Programmable Interrupt Controller) is an
1091 integrated interrupt controller in the CPU. If you have a single-CPU
1092 system which has a processor with a local APIC, you can say Y here to
1093 enable and use it. If you say Y here even though your machine doesn't
1094 have a local APIC, then the kernel will still run with no slowdown at
1095 all. The local APIC supports CPU-generated self-interrupts (timer,
1096 performance counters), and the NMI watchdog which detects hard
1099 config X86_UP_IOAPIC
1100 bool "IO-APIC support on uniprocessors"
1101 depends on X86_UP_APIC
1103 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1104 SMP-capable replacement for PC-style interrupt controllers. Most
1105 SMP systems and many recent uniprocessor systems have one.
1107 If you have a single-CPU system with an IO-APIC, you can say Y here
1108 to use it. If you say Y here even though your machine doesn't have
1109 an IO-APIC, then the kernel will still run with no slowdown at all.
1111 config X86_LOCAL_APIC
1113 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1114 select IRQ_DOMAIN_HIERARCHY
1118 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1120 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1121 bool "Reroute for broken boot IRQs"
1122 depends on X86_IO_APIC
1124 This option enables a workaround that fixes a source of
1125 spurious interrupts. This is recommended when threaded
1126 interrupt handling is used on systems where the generation of
1127 superfluous "boot interrupts" cannot be disabled.
1129 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1130 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1131 kernel does during interrupt handling). On chipsets where this
1132 boot IRQ generation cannot be disabled, this workaround keeps
1133 the original IRQ line masked so that only the equivalent "boot
1134 IRQ" is delivered to the CPUs. The workaround also tells the
1135 kernel to set up the IRQ handler on the boot IRQ line. In this
1136 way only one interrupt is delivered to the kernel. Otherwise
1137 the spurious second interrupt may cause the kernel to bring
1138 down (vital) interrupt lines.
1140 Only affects "broken" chipsets. Interrupt sharing may be
1141 increased on these systems.
1144 bool "Machine Check / overheating reporting"
1145 select GENERIC_ALLOCATOR
1148 Machine Check support allows the processor to notify the
1149 kernel if it detects a problem (e.g. overheating, data corruption).
1150 The action the kernel takes depends on the severity of the problem,
1151 ranging from warning messages to halting the machine.
1153 config X86_MCELOG_LEGACY
1154 bool "Support for deprecated /dev/mcelog character device"
1157 Enable support for /dev/mcelog which is needed by the old mcelog
1158 userspace logging daemon. Consider switching to the new generation
1161 config X86_MCE_INTEL
1163 prompt "Intel MCE features"
1164 depends on X86_MCE && X86_LOCAL_APIC
1166 Additional support for intel specific MCE features such as
1167 the thermal monitor.
1171 prompt "AMD MCE features"
1172 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1174 Additional support for AMD specific MCE features such as
1175 the DRAM Error Threshold.
1177 config X86_ANCIENT_MCE
1178 bool "Support for old Pentium 5 / WinChip machine checks"
1179 depends on X86_32 && X86_MCE
1181 Include support for machine check handling on old Pentium 5 or WinChip
1182 systems. These typically need to be enabled explicitly on the command
1185 config X86_MCE_THRESHOLD
1186 depends on X86_MCE_AMD || X86_MCE_INTEL
1189 config X86_MCE_INJECT
1190 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1191 tristate "Machine check injector support"
1193 Provide support for injecting machine checks for testing purposes.
1194 If you don't know what a machine check is and you don't do kernel
1195 QA it is safe to say n.
1197 source "arch/x86/events/Kconfig"
1199 config X86_LEGACY_VM86
1200 bool "Legacy VM86 support"
1203 This option allows user programs to put the CPU into V8086
1204 mode, which is an 80286-era approximation of 16-bit real mode.
1206 Some very old versions of X and/or vbetool require this option
1207 for user mode setting. Similarly, DOSEMU will use it if
1208 available to accelerate real mode DOS programs. However, any
1209 recent version of DOSEMU, X, or vbetool should be fully
1210 functional even without kernel VM86 support, as they will all
1211 fall back to software emulation. Nevertheless, if you are using
1212 a 16-bit DOS program where 16-bit performance matters, vm86
1213 mode might be faster than emulation and you might want to
1216 Note that any app that works on a 64-bit kernel is unlikely to
1217 need this option, as 64-bit kernels don't, and can't, support
1218 V8086 mode. This option is also unrelated to 16-bit protected
1219 mode and is not needed to run most 16-bit programs under Wine.
1221 Enabling this option increases the complexity of the kernel
1222 and slows down exception handling a tiny bit.
1224 If unsure, say N here.
1228 default X86_LEGACY_VM86
1231 bool "Enable support for 16-bit segments" if EXPERT
1233 depends on MODIFY_LDT_SYSCALL
1235 This option is required by programs like Wine to run 16-bit
1236 protected mode legacy code on x86 processors. Disabling
1237 this option saves about 300 bytes on i386, or around 6K text
1238 plus 16K runtime memory on x86-64,
1242 depends on X86_16BIT && X86_32
1246 depends on X86_16BIT && X86_64
1248 config X86_VSYSCALL_EMULATION
1249 bool "Enable vsyscall emulation" if EXPERT
1253 This enables emulation of the legacy vsyscall page. Disabling
1254 it is roughly equivalent to booting with vsyscall=none, except
1255 that it will also disable the helpful warning if a program
1256 tries to use a vsyscall. With this option set to N, offending
1257 programs will just segfault, citing addresses of the form
1260 This option is required by many programs built before 2013, and
1261 care should be used even with newer programs if set to N.
1263 Disabling this option saves about 7K of kernel size and
1264 possibly 4K of additional runtime pagetable memory.
1266 config X86_IOPL_IOPERM
1267 bool "IOPERM and IOPL Emulation"
1270 This enables the ioperm() and iopl() syscalls which are necessary
1271 for legacy applications.
1273 Legacy IOPL support is an overbroad mechanism which allows user
1274 space aside of accessing all 65536 I/O ports also to disable
1275 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1276 capabilities and permission from potentially active security
1279 The emulation restricts the functionality of the syscall to
1280 only allowing the full range I/O port access, but prevents the
1281 ability to disable interrupts from user space which would be
1282 granted if the hardware IOPL mechanism would be used.
1285 tristate "Toshiba Laptop support"
1288 This adds a driver to safely access the System Management Mode of
1289 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1290 not work on models with a Phoenix BIOS. The System Management Mode
1291 is used to set the BIOS and power saving options on Toshiba portables.
1293 For information on utilities to make use of this driver see the
1294 Toshiba Linux utilities web site at:
1295 <http://www.buzzard.org.uk/toshiba/>.
1297 Say Y if you intend to run this kernel on a Toshiba portable.
1300 config X86_REBOOTFIXUPS
1301 bool "Enable X86 board specific fixups for reboot"
1304 This enables chipset and/or board specific fixups to be done
1305 in order to get reboot to work correctly. This is only needed on
1306 some combinations of hardware and BIOS. The symptom, for which
1307 this config is intended, is when reboot ends with a stalled/hung
1310 Currently, the only fixup is for the Geode machines using
1311 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1313 Say Y if you want to enable the fixup. Currently, it's safe to
1314 enable this option even if you don't need it.
1318 bool "CPU microcode loading support"
1320 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1322 If you say Y here, you will be able to update the microcode on
1323 Intel and AMD processors. The Intel support is for the IA32 family,
1324 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1325 AMD support is for families 0x10 and later. You will obviously need
1326 the actual microcode binary data itself which is not shipped with
1329 The preferred method to load microcode from a detached initrd is described
1330 in Documentation/arch/x86/microcode.rst. For that you need to enable
1331 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1332 initrd for microcode blobs.
1334 In addition, you can build the microcode into the kernel. For that you
1335 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1338 config MICROCODE_INTEL
1339 bool "Intel microcode loading support"
1340 depends on CPU_SUP_INTEL && MICROCODE
1343 This options enables microcode patch loading support for Intel
1346 For the current Intel microcode data package go to
1347 <https://downloadcenter.intel.com> and search for
1348 'Linux Processor Microcode Data File'.
1350 config MICROCODE_AMD
1351 bool "AMD microcode loading support"
1352 depends on CPU_SUP_AMD && MICROCODE
1354 If you select this option, microcode patch loading support for AMD
1355 processors will be enabled.
1357 config MICROCODE_LATE_LOADING
1358 bool "Late microcode loading (DANGEROUS)"
1360 depends on MICROCODE
1362 Loading microcode late, when the system is up and executing instructions
1363 is a tricky business and should be avoided if possible. Just the sequence
1364 of synchronizing all cores and SMT threads is one fragile dance which does
1365 not guarantee that cores might not softlock after the loading. Therefore,
1366 use this at your own risk. Late loading taints the kernel too.
1369 tristate "/dev/cpu/*/msr - Model-specific register support"
1371 This device gives privileged processes access to the x86
1372 Model-Specific Registers (MSRs). It is a character device with
1373 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1374 MSR accesses are directed to a specific CPU on multi-processor
1378 tristate "/dev/cpu/*/cpuid - CPU information support"
1380 This device gives processes access to the x86 CPUID instruction to
1381 be executed on a specific processor. It is a character device
1382 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1386 prompt "High Memory Support"
1393 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1394 However, the address space of 32-bit x86 processors is only 4
1395 Gigabytes large. That means that, if you have a large amount of
1396 physical memory, not all of it can be "permanently mapped" by the
1397 kernel. The physical memory that's not permanently mapped is called
1400 If you are compiling a kernel which will never run on a machine with
1401 more than 1 Gigabyte total physical RAM, answer "off" here (default
1402 choice and suitable for most users). This will result in a "3GB/1GB"
1403 split: 3GB are mapped so that each process sees a 3GB virtual memory
1404 space and the remaining part of the 4GB virtual memory space is used
1405 by the kernel to permanently map as much physical memory as
1408 If the machine has between 1 and 4 Gigabytes physical RAM, then
1411 If more than 4 Gigabytes is used then answer "64GB" here. This
1412 selection turns Intel PAE (Physical Address Extension) mode on.
1413 PAE implements 3-level paging on IA32 processors. PAE is fully
1414 supported by Linux, PAE mode is implemented on all recent Intel
1415 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1416 then the kernel will not boot on CPUs that don't support PAE!
1418 The actual amount of total physical memory will either be
1419 auto detected or can be forced by using a kernel command line option
1420 such as "mem=256M". (Try "man bootparam" or see the documentation of
1421 your boot loader (lilo or loadlin) about how to pass options to the
1422 kernel at boot time.)
1424 If unsure, say "off".
1429 Select this if you have a 32-bit processor and between 1 and 4
1430 gigabytes of physical RAM.
1434 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1437 Select this if you have a 32-bit processor and more than 4
1438 gigabytes of physical RAM.
1443 prompt "Memory split" if EXPERT
1447 Select the desired split between kernel and user memory.
1449 If the address range available to the kernel is less than the
1450 physical memory installed, the remaining memory will be available
1451 as "high memory". Accessing high memory is a little more costly
1452 than low memory, as it needs to be mapped into the kernel first.
1453 Note that increasing the kernel address space limits the range
1454 available to user programs, making the address space there
1455 tighter. Selecting anything other than the default 3G/1G split
1456 will also likely make your kernel incompatible with binary-only
1459 If you are not absolutely sure what you are doing, leave this
1463 bool "3G/1G user/kernel split"
1464 config VMSPLIT_3G_OPT
1466 bool "3G/1G user/kernel split (for full 1G low memory)"
1468 bool "2G/2G user/kernel split"
1469 config VMSPLIT_2G_OPT
1471 bool "2G/2G user/kernel split (for full 2G low memory)"
1473 bool "1G/3G user/kernel split"
1478 default 0xB0000000 if VMSPLIT_3G_OPT
1479 default 0x80000000 if VMSPLIT_2G
1480 default 0x78000000 if VMSPLIT_2G_OPT
1481 default 0x40000000 if VMSPLIT_1G
1487 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1490 bool "PAE (Physical Address Extension) Support"
1491 depends on X86_32 && !HIGHMEM4G
1492 select PHYS_ADDR_T_64BIT
1495 PAE is required for NX support, and furthermore enables
1496 larger swapspace support for non-overcommit purposes. It
1497 has the cost of more pagetable lookup overhead, and also
1498 consumes more pagetable space per process.
1501 bool "Enable 5-level page tables support"
1503 select DYNAMIC_MEMORY_LAYOUT
1504 select SPARSEMEM_VMEMMAP
1507 5-level paging enables access to larger address space:
1508 up to 128 PiB of virtual address space and 4 PiB of
1509 physical address space.
1511 It will be supported by future Intel CPUs.
1513 A kernel with the option enabled can be booted on machines that
1514 support 4- or 5-level paging.
1516 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1521 config X86_DIRECT_GBPAGES
1525 Certain kernel features effectively disable kernel
1526 linear 1 GB mappings (even if the CPU otherwise
1527 supports them), so don't confuse the user by printing
1528 that we have them enabled.
1530 config X86_CPA_STATISTICS
1531 bool "Enable statistic for Change Page Attribute"
1534 Expose statistics about the Change Page Attribute mechanism, which
1535 helps to determine the effectiveness of preserving large and huge
1536 page mappings when mapping protections are changed.
1538 config X86_MEM_ENCRYPT
1539 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1540 select DYNAMIC_PHYSICAL_MASK
1543 config AMD_MEM_ENCRYPT
1544 bool "AMD Secure Memory Encryption (SME) support"
1545 depends on X86_64 && CPU_SUP_AMD
1546 select DMA_COHERENT_POOL
1547 select ARCH_USE_MEMREMAP_PROT
1548 select INSTRUCTION_DECODER
1549 select ARCH_HAS_CC_PLATFORM
1550 select X86_MEM_ENCRYPT
1552 Say yes to enable support for the encryption of system memory.
1553 This requires an AMD processor that supports Secure Memory
1556 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1557 bool "Activate AMD Secure Memory Encryption (SME) by default"
1558 depends on AMD_MEM_ENCRYPT
1560 Say yes to have system memory encrypted by default if running on
1561 an AMD processor that supports Secure Memory Encryption (SME).
1563 If set to Y, then the encryption of system memory can be
1564 deactivated with the mem_encrypt=off command line option.
1566 If set to N, then the encryption of system memory can be
1567 activated with the mem_encrypt=on command line option.
1569 # Common NUMA Features
1571 bool "NUMA Memory Allocation and Scheduler Support"
1573 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1574 default y if X86_BIGSMP
1575 select USE_PERCPU_NUMA_NODE_ID
1577 Enable NUMA (Non-Uniform Memory Access) support.
1579 The kernel will try to allocate memory used by a CPU on the
1580 local memory controller of the CPU and add some more
1581 NUMA awareness to the kernel.
1583 For 64-bit this is recommended if the system is Intel Core i7
1584 (or later), AMD Opteron, or EM64T NUMA.
1586 For 32-bit this is only needed if you boot a 32-bit
1587 kernel on a 64-bit NUMA platform.
1589 Otherwise, you should say N.
1593 prompt "Old style AMD Opteron NUMA detection"
1594 depends on X86_64 && NUMA && PCI
1596 Enable AMD NUMA node topology detection. You should say Y here if
1597 you have a multi processor AMD system. This uses an old method to
1598 read the NUMA configuration directly from the builtin Northbridge
1599 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1600 which also takes priority if both are compiled in.
1602 config X86_64_ACPI_NUMA
1604 prompt "ACPI NUMA detection"
1605 depends on X86_64 && NUMA && ACPI && PCI
1608 Enable ACPI SRAT based node topology detection.
1611 bool "NUMA emulation"
1614 Enable NUMA emulation. A flat machine will be split
1615 into virtual nodes when booted with "numa=fake=N", where N is the
1616 number of nodes. This is only useful for debugging.
1619 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1621 default "10" if MAXSMP
1622 default "6" if X86_64
1626 Specify the maximum number of NUMA Nodes available on the target
1627 system. Increases memory reserved to accommodate various tables.
1629 config ARCH_FLATMEM_ENABLE
1631 depends on X86_32 && !NUMA
1633 config ARCH_SPARSEMEM_ENABLE
1635 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1636 select SPARSEMEM_STATIC if X86_32
1637 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1639 config ARCH_SPARSEMEM_DEFAULT
1640 def_bool X86_64 || (NUMA && X86_32)
1642 config ARCH_SELECT_MEMORY_MODEL
1644 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1646 config ARCH_MEMORY_PROBE
1647 bool "Enable sysfs memory/probe interface"
1648 depends on MEMORY_HOTPLUG
1650 This option enables a sysfs memory/probe interface for testing.
1651 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1652 If you are unsure how to answer this question, answer N.
1654 config ARCH_PROC_KCORE_TEXT
1656 depends on X86_64 && PROC_KCORE
1658 config ILLEGAL_POINTER_VALUE
1661 default 0xdead000000000000 if X86_64
1663 config X86_PMEM_LEGACY_DEVICE
1666 config X86_PMEM_LEGACY
1667 tristate "Support non-standard NVDIMMs and ADR protected memory"
1668 depends on PHYS_ADDR_T_64BIT
1670 select X86_PMEM_LEGACY_DEVICE
1671 select NUMA_KEEP_MEMINFO if NUMA
1674 Treat memory marked using the non-standard e820 type of 12 as used
1675 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1676 The kernel will offer these regions to the 'pmem' driver so
1677 they can be used for persistent storage.
1682 bool "Allocate 3rd-level pagetables from highmem"
1685 The VM uses one page table entry for each page of physical memory.
1686 For systems with a lot of RAM, this can be wasteful of precious
1687 low memory. Setting this option will put user-space page table
1688 entries in high memory.
1690 config X86_CHECK_BIOS_CORRUPTION
1691 bool "Check for low memory corruption"
1693 Periodically check for memory corruption in low memory, which
1694 is suspected to be caused by BIOS. Even when enabled in the
1695 configuration, it is disabled at runtime. Enable it by
1696 setting "memory_corruption_check=1" on the kernel command
1697 line. By default it scans the low 64k of memory every 60
1698 seconds; see the memory_corruption_check_size and
1699 memory_corruption_check_period parameters in
1700 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1702 When enabled with the default parameters, this option has
1703 almost no overhead, as it reserves a relatively small amount
1704 of memory and scans it infrequently. It both detects corruption
1705 and prevents it from affecting the running system.
1707 It is, however, intended as a diagnostic tool; if repeatable
1708 BIOS-originated corruption always affects the same memory,
1709 you can use memmap= to prevent the kernel from using that
1712 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1713 bool "Set the default setting of memory_corruption_check"
1714 depends on X86_CHECK_BIOS_CORRUPTION
1717 Set whether the default state of memory_corruption_check is
1720 config MATH_EMULATION
1722 depends on MODIFY_LDT_SYSCALL
1723 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1725 Linux can emulate a math coprocessor (used for floating point
1726 operations) if you don't have one. 486DX and Pentium processors have
1727 a math coprocessor built in, 486SX and 386 do not, unless you added
1728 a 487DX or 387, respectively. (The messages during boot time can
1729 give you some hints here ["man dmesg"].) Everyone needs either a
1730 coprocessor or this emulation.
1732 If you don't have a math coprocessor, you need to say Y here; if you
1733 say Y here even though you have a coprocessor, the coprocessor will
1734 be used nevertheless. (This behavior can be changed with the kernel
1735 command line option "no387", which comes handy if your coprocessor
1736 is broken. Try "man bootparam" or see the documentation of your boot
1737 loader (lilo or loadlin) about how to pass options to the kernel at
1738 boot time.) This means that it is a good idea to say Y here if you
1739 intend to use this kernel on different machines.
1741 More information about the internals of the Linux math coprocessor
1742 emulation can be found in <file:arch/x86/math-emu/README>.
1744 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1745 kernel, it won't hurt.
1749 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1751 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1752 the Memory Type Range Registers (MTRRs) may be used to control
1753 processor access to memory ranges. This is most useful if you have
1754 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1755 allows bus write transfers to be combined into a larger transfer
1756 before bursting over the PCI/AGP bus. This can increase performance
1757 of image write operations 2.5 times or more. Saying Y here creates a
1758 /proc/mtrr file which may be used to manipulate your processor's
1759 MTRRs. Typically the X server should use this.
1761 This code has a reasonably generic interface so that similar
1762 control registers on other processors can be easily supported
1765 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1766 Registers (ARRs) which provide a similar functionality to MTRRs. For
1767 these, the ARRs are used to emulate the MTRRs.
1768 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1769 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1770 write-combining. All of these processors are supported by this code
1771 and it makes sense to say Y here if you have one of them.
1773 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1774 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1775 can lead to all sorts of problems, so it's good to say Y here.
1777 You can safely say Y even if your machine doesn't have MTRRs, you'll
1778 just add about 9 KB to your kernel.
1780 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1782 config MTRR_SANITIZER
1784 prompt "MTRR cleanup support"
1787 Convert MTRR layout from continuous to discrete, so X drivers can
1788 add writeback entries.
1790 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1791 The largest mtrr entry size for a continuous block can be set with
1796 config MTRR_SANITIZER_ENABLE_DEFAULT
1797 int "MTRR cleanup enable value (0-1)"
1800 depends on MTRR_SANITIZER
1802 Enable mtrr cleanup default value
1804 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1805 int "MTRR cleanup spare reg num (0-7)"
1808 depends on MTRR_SANITIZER
1810 mtrr cleanup spare entries default, it can be changed via
1811 mtrr_spare_reg_nr=N on the kernel command line.
1815 prompt "x86 PAT support" if EXPERT
1818 Use PAT attributes to setup page level cache control.
1820 PATs are the modern equivalents of MTRRs and are much more
1821 flexible than MTRRs.
1823 Say N here if you see bootup problems (boot crash, boot hang,
1824 spontaneous reboots) or a non-working video driver.
1828 config ARCH_USES_PG_UNCACHED
1834 prompt "User Mode Instruction Prevention" if EXPERT
1836 User Mode Instruction Prevention (UMIP) is a security feature in
1837 some x86 processors. If enabled, a general protection fault is
1838 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1839 executed in user mode. These instructions unnecessarily expose
1840 information about the hardware state.
1842 The vast majority of applications do not use these instructions.
1843 For the very few that do, software emulation is provided in
1844 specific cases in protected and virtual-8086 modes. Emulated
1848 # GCC >= 9 and binutils >= 2.29
1849 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1851 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1852 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1853 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1854 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1857 config X86_KERNEL_IBT
1858 prompt "Indirect Branch Tracking"
1860 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1861 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1862 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1865 Build the kernel with support for Indirect Branch Tracking, a
1866 hardware support course-grain forward-edge Control Flow Integrity
1867 protection. It enforces that all indirect calls must land on
1868 an ENDBR instruction, as such, the compiler will instrument the
1869 code with them to make this happen.
1871 In addition to building the kernel with IBT, seal all functions that
1872 are not indirect call targets, avoiding them ever becoming one.
1874 This requires LTO like objtool runs and will slow down the build. It
1875 does significantly reduce the number of ENDBR instructions in the
1878 config X86_INTEL_MEMORY_PROTECTION_KEYS
1879 prompt "Memory Protection Keys"
1881 # Note: only available in 64-bit mode
1882 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1883 select ARCH_USES_HIGH_VMA_FLAGS
1884 select ARCH_HAS_PKEYS
1886 Memory Protection Keys provides a mechanism for enforcing
1887 page-based protections, but without requiring modification of the
1888 page tables when an application changes protection domains.
1890 For details, see Documentation/core-api/protection-keys.rst
1895 prompt "TSX enable mode"
1896 depends on CPU_SUP_INTEL
1897 default X86_INTEL_TSX_MODE_OFF
1899 Intel's TSX (Transactional Synchronization Extensions) feature
1900 allows to optimize locking protocols through lock elision which
1901 can lead to a noticeable performance boost.
1903 On the other hand it has been shown that TSX can be exploited
1904 to form side channel attacks (e.g. TAA) and chances are there
1905 will be more of those attacks discovered in the future.
1907 Therefore TSX is not enabled by default (aka tsx=off). An admin
1908 might override this decision by tsx=on the command line parameter.
1909 Even with TSX enabled, the kernel will attempt to enable the best
1910 possible TAA mitigation setting depending on the microcode available
1911 for the particular machine.
1913 This option allows to set the default tsx mode between tsx=on, =off
1914 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1917 Say off if not sure, auto if TSX is in use but it should be used on safe
1918 platforms or on if TSX is in use and the security aspect of tsx is not
1921 config X86_INTEL_TSX_MODE_OFF
1924 TSX is disabled if possible - equals to tsx=off command line parameter.
1926 config X86_INTEL_TSX_MODE_ON
1929 TSX is always enabled on TSX capable HW - equals the tsx=on command
1932 config X86_INTEL_TSX_MODE_AUTO
1935 TSX is enabled on TSX capable HW that is believed to be safe against
1936 side channel attacks- equals the tsx=auto command line parameter.
1940 bool "Software Guard eXtensions (SGX)"
1941 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1943 depends on CRYPTO_SHA256=y
1945 select NUMA_KEEP_MEMINFO if NUMA
1948 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1949 that can be used by applications to set aside private regions of code
1950 and data, referred to as enclaves. An enclave's private memory can
1951 only be accessed by code running within the enclave. Accesses from
1952 outside the enclave, including other enclaves, are disallowed by
1958 bool "EFI runtime service support"
1961 select EFI_RUNTIME_WRAPPERS
1962 select ARCH_USE_MEMREMAP_PROT
1964 This enables the kernel to use EFI runtime services that are
1965 available (such as the EFI variable services).
1967 This option is only useful on systems that have EFI firmware.
1968 In addition, you should use the latest ELILO loader available
1969 at <http://elilo.sourceforge.net> in order to take advantage
1970 of EFI runtime services. However, even with this option, the
1971 resultant kernel should continue to boot on existing non-EFI
1975 bool "EFI stub support"
1979 This kernel feature allows a bzImage to be loaded directly
1980 by EFI firmware without the use of a bootloader.
1982 See Documentation/admin-guide/efi-stub.rst for more information.
1984 config EFI_HANDOVER_PROTOCOL
1985 bool "EFI handover protocol (DEPRECATED)"
1989 Select this in order to include support for the deprecated EFI
1990 handover protocol, which defines alternative entry points into the
1991 EFI stub. This is a practice that has no basis in the UEFI
1992 specification, and requires a priori knowledge on the part of the
1993 bootloader about Linux/x86 specific ways of passing the command line
1994 and initrd, and where in memory those assets may be loaded.
1996 If in doubt, say Y. Even though the corresponding support is not
1997 present in upstream GRUB or other bootloaders, most distros build
1998 GRUB with numerous downstream patches applied, and may rely on the
1999 handover protocol as as result.
2002 bool "EFI mixed-mode support"
2003 depends on EFI_STUB && X86_64
2005 Enabling this feature allows a 64-bit kernel to be booted
2006 on a 32-bit firmware, provided that your CPU supports 64-bit
2009 Note that it is not possible to boot a mixed-mode enabled
2010 kernel via the EFI boot stub - a bootloader that supports
2011 the EFI handover protocol must be used.
2015 config EFI_FAKE_MEMMAP
2016 bool "Enable EFI fake memory map"
2019 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2020 this parameter, you can add arbitrary attribute to specific memory
2021 range by updating original (firmware provided) EFI memmap. This is
2022 useful for debugging of EFI memmap related feature, e.g., Address
2023 Range Mirroring feature.
2025 config EFI_MAX_FAKE_MEM
2026 int "maximum allowable number of ranges in efi_fake_mem boot option"
2027 depends on EFI_FAKE_MEMMAP
2031 Maximum allowable number of ranges in efi_fake_mem boot option.
2032 Ranges can be set up to this value using comma-separated list.
2033 The default value is 8.
2035 config EFI_RUNTIME_MAP
2036 bool "Export EFI runtime maps to sysfs" if EXPERT
2040 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2041 That memory map is required by the 2nd kernel to set up EFI virtual
2042 mappings after kexec, but can also be used for debugging purposes.
2044 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2046 source "kernel/Kconfig.hz"
2049 bool "kexec system call"
2052 kexec is a system call that implements the ability to shutdown your
2053 current kernel, and to start another kernel. It is like a reboot
2054 but it is independent of the system firmware. And like a reboot
2055 you can start any kernel with it, not just Linux.
2057 The name comes from the similarity to the exec system call.
2059 It is an ongoing process to be certain the hardware in a machine
2060 is properly shutdown, so do not be surprised if this code does not
2061 initially work for you. As of this writing the exact hardware
2062 interface is strongly in flux, so no good recommendation can be
2066 bool "kexec file based system call"
2068 select HAVE_IMA_KEXEC if IMA
2071 depends on CRYPTO_SHA256=y
2073 This is new version of kexec system call. This system call is
2074 file based and takes file descriptors as system call argument
2075 for kernel and initramfs as opposed to list of segments as
2076 accepted by previous system call.
2078 config ARCH_HAS_KEXEC_PURGATORY
2082 bool "Verify kernel signature during kexec_file_load() syscall"
2083 depends on KEXEC_FILE
2086 This option makes the kexec_file_load() syscall check for a valid
2087 signature of the kernel image. The image can still be loaded without
2088 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2089 there's a signature that we can check, then it must be valid.
2091 In addition to this option, you need to enable signature
2092 verification for the corresponding kernel image type being
2093 loaded in order for this to work.
2095 config KEXEC_SIG_FORCE
2096 bool "Require a valid signature in kexec_file_load() syscall"
2097 depends on KEXEC_SIG
2099 This option makes kernel signature verification mandatory for
2100 the kexec_file_load() syscall.
2102 config KEXEC_BZIMAGE_VERIFY_SIG
2103 bool "Enable bzImage signature verification support"
2104 depends on KEXEC_SIG
2105 depends on SIGNED_PE_FILE_VERIFICATION
2106 select SYSTEM_TRUSTED_KEYRING
2108 Enable bzImage signature verification support.
2111 bool "kernel crash dumps"
2112 depends on X86_64 || (X86_32 && HIGHMEM)
2114 Generate crash dump after being started by kexec.
2115 This should be normally only set in special crash dump kernels
2116 which are loaded in the main kernel with kexec-tools into
2117 a specially reserved region and then later executed after
2118 a crash by kdump/kexec. The crash dump kernel must be compiled
2119 to a memory address not used by the main kernel or BIOS using
2120 PHYSICAL_START, or it must be built as a relocatable image
2121 (CONFIG_RELOCATABLE=y).
2122 For more details see Documentation/admin-guide/kdump/kdump.rst
2126 depends on KEXEC && HIBERNATION
2128 Jump between original kernel and kexeced kernel and invoke
2129 code in physical address mode via KEXEC
2131 config PHYSICAL_START
2132 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2135 This gives the physical address where the kernel is loaded.
2137 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2138 bzImage will decompress itself to above physical address and
2139 run from there. Otherwise, bzImage will run from the address where
2140 it has been loaded by the boot loader and will ignore above physical
2143 In normal kdump cases one does not have to set/change this option
2144 as now bzImage can be compiled as a completely relocatable image
2145 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2146 address. This option is mainly useful for the folks who don't want
2147 to use a bzImage for capturing the crash dump and want to use a
2148 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2149 to be specifically compiled to run from a specific memory area
2150 (normally a reserved region) and this option comes handy.
2152 So if you are using bzImage for capturing the crash dump,
2153 leave the value here unchanged to 0x1000000 and set
2154 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2155 for capturing the crash dump change this value to start of
2156 the reserved region. In other words, it can be set based on
2157 the "X" value as specified in the "crashkernel=YM@XM"
2158 command line boot parameter passed to the panic-ed
2159 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2160 for more details about crash dumps.
2162 Usage of bzImage for capturing the crash dump is recommended as
2163 one does not have to build two kernels. Same kernel can be used
2164 as production kernel and capture kernel. Above option should have
2165 gone away after relocatable bzImage support is introduced. But it
2166 is present because there are users out there who continue to use
2167 vmlinux for dump capture. This option should go away down the
2170 Don't change this unless you know what you are doing.
2173 bool "Build a relocatable kernel"
2176 This builds a kernel image that retains relocation information
2177 so it can be loaded someplace besides the default 1MB.
2178 The relocations tend to make the kernel binary about 10% larger,
2179 but are discarded at runtime.
2181 One use is for the kexec on panic case where the recovery kernel
2182 must live at a different physical address than the primary
2185 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2186 it has been loaded at and the compile time physical address
2187 (CONFIG_PHYSICAL_START) is used as the minimum location.
2189 config RANDOMIZE_BASE
2190 bool "Randomize the address of the kernel image (KASLR)"
2191 depends on RELOCATABLE
2194 In support of Kernel Address Space Layout Randomization (KASLR),
2195 this randomizes the physical address at which the kernel image
2196 is decompressed and the virtual address where the kernel
2197 image is mapped, as a security feature that deters exploit
2198 attempts relying on knowledge of the location of kernel
2201 On 64-bit, the kernel physical and virtual addresses are
2202 randomized separately. The physical address will be anywhere
2203 between 16MB and the top of physical memory (up to 64TB). The
2204 virtual address will be randomized from 16MB up to 1GB (9 bits
2205 of entropy). Note that this also reduces the memory space
2206 available to kernel modules from 1.5GB to 1GB.
2208 On 32-bit, the kernel physical and virtual addresses are
2209 randomized together. They will be randomized from 16MB up to
2210 512MB (8 bits of entropy).
2212 Entropy is generated using the RDRAND instruction if it is
2213 supported. If RDTSC is supported, its value is mixed into
2214 the entropy pool as well. If neither RDRAND nor RDTSC are
2215 supported, then entropy is read from the i8254 timer. The
2216 usable entropy is limited by the kernel being built using
2217 2GB addressing, and that PHYSICAL_ALIGN must be at a
2218 minimum of 2MB. As a result, only 10 bits of entropy are
2219 theoretically possible, but the implementations are further
2220 limited due to memory layouts.
2224 # Relocation on x86 needs some additional build support
2225 config X86_NEED_RELOCS
2227 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2229 config PHYSICAL_ALIGN
2230 hex "Alignment value to which kernel should be aligned"
2232 range 0x2000 0x1000000 if X86_32
2233 range 0x200000 0x1000000 if X86_64
2235 This value puts the alignment restrictions on physical address
2236 where kernel is loaded and run from. Kernel is compiled for an
2237 address which meets above alignment restriction.
2239 If bootloader loads the kernel at a non-aligned address and
2240 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2241 address aligned to above value and run from there.
2243 If bootloader loads the kernel at a non-aligned address and
2244 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2245 load address and decompress itself to the address it has been
2246 compiled for and run from there. The address for which kernel is
2247 compiled already meets above alignment restrictions. Hence the
2248 end result is that kernel runs from a physical address meeting
2249 above alignment restrictions.
2251 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2252 this value must be a multiple of 0x200000.
2254 Don't change this unless you know what you are doing.
2256 config DYNAMIC_MEMORY_LAYOUT
2259 This option makes base addresses of vmalloc and vmemmap as well as
2260 __PAGE_OFFSET movable during boot.
2262 config RANDOMIZE_MEMORY
2263 bool "Randomize the kernel memory sections"
2265 depends on RANDOMIZE_BASE
2266 select DYNAMIC_MEMORY_LAYOUT
2267 default RANDOMIZE_BASE
2269 Randomizes the base virtual address of kernel memory sections
2270 (physical memory mapping, vmalloc & vmemmap). This security feature
2271 makes exploits relying on predictable memory locations less reliable.
2273 The order of allocations remains unchanged. Entropy is generated in
2274 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2275 configuration have in average 30,000 different possible virtual
2276 addresses for each memory section.
2280 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2281 hex "Physical memory mapping padding" if EXPERT
2282 depends on RANDOMIZE_MEMORY
2283 default "0xa" if MEMORY_HOTPLUG
2285 range 0x1 0x40 if MEMORY_HOTPLUG
2288 Define the padding in terabytes added to the existing physical
2289 memory size during kernel memory randomization. It is useful
2290 for memory hotplug support but reduces the entropy available for
2291 address randomization.
2293 If unsure, leave at the default value.
2295 config ADDRESS_MASKING
2296 bool "Linear Address Masking support"
2299 Linear Address Masking (LAM) modifies the checking that is applied
2300 to 64-bit linear addresses, allowing software to use of the
2301 untranslated address bits for metadata.
2303 The capability can be used for efficient address sanitizers (ASAN)
2304 implementation and for optimizations in JITs.
2312 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2313 depends on COMPAT_32
2315 Certain buggy versions of glibc will crash if they are
2316 presented with a 32-bit vDSO that is not mapped at the address
2317 indicated in its segment table.
2319 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2320 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2321 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2322 the only released version with the bug, but OpenSUSE 9
2323 contains a buggy "glibc 2.3.2".
2325 The symptom of the bug is that everything crashes on startup, saying:
2326 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2328 Saying Y here changes the default value of the vdso32 boot
2329 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2330 This works around the glibc bug but hurts performance.
2332 If unsure, say N: if you are compiling your own kernel, you
2333 are unlikely to be using a buggy version of glibc.
2336 prompt "vsyscall table for legacy applications"
2338 default LEGACY_VSYSCALL_XONLY
2340 Legacy user code that does not know how to find the vDSO expects
2341 to be able to issue three syscalls by calling fixed addresses in
2342 kernel space. Since this location is not randomized with ASLR,
2343 it can be used to assist security vulnerability exploitation.
2345 This setting can be changed at boot time via the kernel command
2346 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2347 is deprecated and can only be enabled using the kernel command
2350 On a system with recent enough glibc (2.14 or newer) and no
2351 static binaries, you can say None without a performance penalty
2352 to improve security.
2354 If unsure, select "Emulate execution only".
2356 config LEGACY_VSYSCALL_XONLY
2357 bool "Emulate execution only"
2359 The kernel traps and emulates calls into the fixed vsyscall
2360 address mapping and does not allow reads. This
2361 configuration is recommended when userspace might use the
2362 legacy vsyscall area but support for legacy binary
2363 instrumentation of legacy code is not needed. It mitigates
2364 certain uses of the vsyscall area as an ASLR-bypassing
2367 config LEGACY_VSYSCALL_NONE
2370 There will be no vsyscall mapping at all. This will
2371 eliminate any risk of ASLR bypass due to the vsyscall
2372 fixed address mapping. Attempts to use the vsyscalls
2373 will be reported to dmesg, so that either old or
2374 malicious userspace programs can be identified.
2379 bool "Built-in kernel command line"
2381 Allow for specifying boot arguments to the kernel at
2382 build time. On some systems (e.g. embedded ones), it is
2383 necessary or convenient to provide some or all of the
2384 kernel boot arguments with the kernel itself (that is,
2385 to not rely on the boot loader to provide them.)
2387 To compile command line arguments into the kernel,
2388 set this option to 'Y', then fill in the
2389 boot arguments in CONFIG_CMDLINE.
2391 Systems with fully functional boot loaders (i.e. non-embedded)
2392 should leave this option set to 'N'.
2395 string "Built-in kernel command string"
2396 depends on CMDLINE_BOOL
2399 Enter arguments here that should be compiled into the kernel
2400 image and used at boot time. If the boot loader provides a
2401 command line at boot time, it is appended to this string to
2402 form the full kernel command line, when the system boots.
2404 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2405 change this behavior.
2407 In most cases, the command line (whether built-in or provided
2408 by the boot loader) should specify the device for the root
2411 config CMDLINE_OVERRIDE
2412 bool "Built-in command line overrides boot loader arguments"
2413 depends on CMDLINE_BOOL && CMDLINE != ""
2415 Set this option to 'Y' to have the kernel ignore the boot loader
2416 command line, and use ONLY the built-in command line.
2418 This is used to work around broken boot loaders. This should
2419 be set to 'N' under normal conditions.
2421 config MODIFY_LDT_SYSCALL
2422 bool "Enable the LDT (local descriptor table)" if EXPERT
2425 Linux can allow user programs to install a per-process x86
2426 Local Descriptor Table (LDT) using the modify_ldt(2) system
2427 call. This is required to run 16-bit or segmented code such as
2428 DOSEMU or some Wine programs. It is also used by some very old
2429 threading libraries.
2431 Enabling this feature adds a small amount of overhead to
2432 context switches and increases the low-level kernel attack
2433 surface. Disabling it removes the modify_ldt(2) system call.
2435 Saying 'N' here may make sense for embedded or server kernels.
2437 config STRICT_SIGALTSTACK_SIZE
2438 bool "Enforce strict size checking for sigaltstack"
2439 depends on DYNAMIC_SIGFRAME
2441 For historical reasons MINSIGSTKSZ is a constant which became
2442 already too small with AVX512 support. Add a mechanism to
2443 enforce strict checking of the sigaltstack size against the
2444 real size of the FPU frame. This option enables the check
2445 by default. It can also be controlled via the kernel command
2446 line option 'strict_sas_size' independent of this config
2447 switch. Enabling it might break existing applications which
2448 allocate a too small sigaltstack but 'work' because they
2449 never get a signal delivered.
2451 Say 'N' unless you want to really enforce this check.
2453 source "kernel/livepatch/Kconfig"
2458 def_bool $(cc-option,-mharden-sls=all)
2460 config CC_HAS_RETURN_THUNK
2461 def_bool $(cc-option,-mfunction-return=thunk-extern)
2463 config CC_HAS_ENTRY_PADDING
2464 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2466 config FUNCTION_PADDING_CFI
2468 default 59 if FUNCTION_ALIGNMENT_64B
2469 default 27 if FUNCTION_ALIGNMENT_32B
2470 default 11 if FUNCTION_ALIGNMENT_16B
2471 default 3 if FUNCTION_ALIGNMENT_8B
2474 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2475 # except Kconfig can't do arithmetic :/
2476 config FUNCTION_PADDING_BYTES
2478 default FUNCTION_PADDING_CFI if CFI_CLANG
2479 default FUNCTION_ALIGNMENT
2483 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2484 select FUNCTION_ALIGNMENT_16B
2488 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2491 config HAVE_CALL_THUNKS
2493 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2499 config PREFIX_SYMBOLS
2501 depends on CALL_PADDING && !CFI_CLANG
2503 menuconfig SPECULATION_MITIGATIONS
2504 bool "Mitigations for speculative execution vulnerabilities"
2507 Say Y here to enable options which enable mitigations for
2508 speculative execution hardware vulnerabilities.
2510 If you say N, all mitigations will be disabled. You really
2511 should know what you are doing to say so.
2513 if SPECULATION_MITIGATIONS
2515 config PAGE_TABLE_ISOLATION
2516 bool "Remove the kernel mapping in user mode"
2518 depends on (X86_64 || X86_PAE)
2520 This feature reduces the number of hardware side channels by
2521 ensuring that the majority of kernel addresses are not mapped
2524 See Documentation/arch/x86/pti.rst for more details.
2527 bool "Avoid speculative indirect branches in kernel"
2528 select OBJTOOL if HAVE_OBJTOOL
2531 Compile kernel with the retpoline compiler options to guard against
2532 kernel-to-user data leaks by avoiding speculative indirect
2533 branches. Requires a compiler with -mindirect-branch=thunk-extern
2534 support for full protection. The kernel may run slower.
2537 bool "Enable return-thunks"
2538 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2539 select OBJTOOL if HAVE_OBJTOOL
2542 Compile the kernel with the return-thunks compiler option to guard
2543 against kernel-to-user data leaks by avoiding return speculation.
2544 Requires a compiler with -mfunction-return=thunk-extern
2545 support for full protection. The kernel may run slower.
2547 config CPU_UNRET_ENTRY
2548 bool "Enable UNRET on kernel entry"
2549 depends on CPU_SUP_AMD && RETHUNK && X86_64
2552 Compile the kernel with support for the retbleed=unret mitigation.
2554 config CALL_DEPTH_TRACKING
2555 bool "Mitigate RSB underflow with call depth tracking"
2556 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2557 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2561 Compile the kernel with call depth tracking to mitigate the Intel
2562 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2563 mitigation is off by default and needs to be enabled on the
2564 kernel command line via the retbleed=stuff option. For
2565 non-affected systems the overhead of this option is marginal as
2566 the call depth tracking is using run-time generated call thunks
2567 in a compiler generated padding area and call patching. This
2568 increases text size by ~5%. For non affected systems this space
2569 is unused. On affected SKL systems this results in a significant
2570 performance gain over the IBRS mitigation.
2572 config CALL_THUNKS_DEBUG
2573 bool "Enable call thunks and call depth tracking debugging"
2574 depends on CALL_DEPTH_TRACKING
2575 select FUNCTION_ALIGNMENT_32B
2578 Enable call/ret counters for imbalance detection and build in
2579 a noisy dmesg about callthunks generation and call patching for
2580 trouble shooting. The debug prints need to be enabled on the
2581 kernel command line with 'debug-callthunks'.
2582 Only enable this when you are debugging call thunks as this
2583 creates a noticeable runtime overhead. If unsure say N.
2585 config CPU_IBPB_ENTRY
2586 bool "Enable IBPB on kernel entry"
2587 depends on CPU_SUP_AMD && X86_64
2590 Compile the kernel with support for the retbleed=ibpb mitigation.
2592 config CPU_IBRS_ENTRY
2593 bool "Enable IBRS on kernel entry"
2594 depends on CPU_SUP_INTEL && X86_64
2597 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2598 This mitigates both spectre_v2 and retbleed at great cost to
2602 bool "Mitigate Straight-Line-Speculation"
2603 depends on CC_HAS_SLS && X86_64
2604 select OBJTOOL if HAVE_OBJTOOL
2607 Compile the kernel with straight-line-speculation options to guard
2608 against straight line speculation. The kernel image might be slightly
2613 config ARCH_HAS_ADD_PAGES
2615 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2617 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2620 menu "Power management and ACPI options"
2622 config ARCH_HIBERNATION_HEADER
2624 depends on HIBERNATION
2626 source "kernel/power/Kconfig"
2628 source "drivers/acpi/Kconfig"
2635 tristate "APM (Advanced Power Management) BIOS support"
2636 depends on X86_32 && PM_SLEEP
2638 APM is a BIOS specification for saving power using several different
2639 techniques. This is mostly useful for battery powered laptops with
2640 APM compliant BIOSes. If you say Y here, the system time will be
2641 reset after a RESUME operation, the /proc/apm device will provide
2642 battery status information, and user-space programs will receive
2643 notification of APM "events" (e.g. battery status change).
2645 If you select "Y" here, you can disable actual use of the APM
2646 BIOS by passing the "apm=off" option to the kernel at boot time.
2648 Note that the APM support is almost completely disabled for
2649 machines with more than one CPU.
2651 In order to use APM, you will need supporting software. For location
2652 and more information, read <file:Documentation/power/apm-acpi.rst>
2653 and the Battery Powered Linux mini-HOWTO, available from
2654 <http://www.tldp.org/docs.html#howto>.
2656 This driver does not spin down disk drives (see the hdparm(8)
2657 manpage ("man 8 hdparm") for that), and it doesn't turn off
2658 VESA-compliant "green" monitors.
2660 This driver does not support the TI 4000M TravelMate and the ACER
2661 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2662 desktop machines also don't have compliant BIOSes, and this driver
2663 may cause those machines to panic during the boot phase.
2665 Generally, if you don't have a battery in your machine, there isn't
2666 much point in using this driver and you should say N. If you get
2667 random kernel OOPSes or reboots that don't seem to be related to
2668 anything, try disabling/enabling this option (or disabling/enabling
2671 Some other things you should try when experiencing seemingly random,
2674 1) make sure that you have enough swap space and that it is
2676 2) pass the "idle=poll" option to the kernel
2677 3) switch on floating point emulation in the kernel and pass
2678 the "no387" option to the kernel
2679 4) pass the "floppy=nodma" option to the kernel
2680 5) pass the "mem=4M" option to the kernel (thereby disabling
2681 all but the first 4 MB of RAM)
2682 6) make sure that the CPU is not over clocked.
2683 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2684 8) disable the cache from your BIOS settings
2685 9) install a fan for the video card or exchange video RAM
2686 10) install a better fan for the CPU
2687 11) exchange RAM chips
2688 12) exchange the motherboard.
2690 To compile this driver as a module, choose M here: the
2691 module will be called apm.
2695 config APM_IGNORE_USER_SUSPEND
2696 bool "Ignore USER SUSPEND"
2698 This option will ignore USER SUSPEND requests. On machines with a
2699 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2700 series notebooks, it is necessary to say Y because of a BIOS bug.
2702 config APM_DO_ENABLE
2703 bool "Enable PM at boot time"
2705 Enable APM features at boot time. From page 36 of the APM BIOS
2706 specification: "When disabled, the APM BIOS does not automatically
2707 power manage devices, enter the Standby State, enter the Suspend
2708 State, or take power saving steps in response to CPU Idle calls."
2709 This driver will make CPU Idle calls when Linux is idle (unless this
2710 feature is turned off -- see "Do CPU IDLE calls", below). This
2711 should always save battery power, but more complicated APM features
2712 will be dependent on your BIOS implementation. You may need to turn
2713 this option off if your computer hangs at boot time when using APM
2714 support, or if it beeps continuously instead of suspending. Turn
2715 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2716 T400CDT. This is off by default since most machines do fine without
2721 bool "Make CPU Idle calls when idle"
2723 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2724 On some machines, this can activate improved power savings, such as
2725 a slowed CPU clock rate, when the machine is idle. These idle calls
2726 are made after the idle loop has run for some length of time (e.g.,
2727 333 mS). On some machines, this will cause a hang at boot time or
2728 whenever the CPU becomes idle. (On machines with more than one CPU,
2729 this option does nothing.)
2731 config APM_DISPLAY_BLANK
2732 bool "Enable console blanking using APM"
2734 Enable console blanking using the APM. Some laptops can use this to
2735 turn off the LCD backlight when the screen blanker of the Linux
2736 virtual console blanks the screen. Note that this is only used by
2737 the virtual console screen blanker, and won't turn off the backlight
2738 when using the X Window system. This also doesn't have anything to
2739 do with your VESA-compliant power-saving monitor. Further, this
2740 option doesn't work for all laptops -- it might not turn off your
2741 backlight at all, or it might print a lot of errors to the console,
2742 especially if you are using gpm.
2744 config APM_ALLOW_INTS
2745 bool "Allow interrupts during APM BIOS calls"
2747 Normally we disable external interrupts while we are making calls to
2748 the APM BIOS as a measure to lessen the effects of a badly behaving
2749 BIOS implementation. The BIOS should reenable interrupts if it
2750 needs to. Unfortunately, some BIOSes do not -- especially those in
2751 many of the newer IBM Thinkpads. If you experience hangs when you
2752 suspend, try setting this to Y. Otherwise, say N.
2756 source "drivers/cpufreq/Kconfig"
2758 source "drivers/cpuidle/Kconfig"
2760 source "drivers/idle/Kconfig"
2764 menu "Bus options (PCI etc.)"
2767 prompt "PCI access mode"
2768 depends on X86_32 && PCI
2771 On PCI systems, the BIOS can be used to detect the PCI devices and
2772 determine their configuration. However, some old PCI motherboards
2773 have BIOS bugs and may crash if this is done. Also, some embedded
2774 PCI-based systems don't have any BIOS at all. Linux can also try to
2775 detect the PCI hardware directly without using the BIOS.
2777 With this option, you can specify how Linux should detect the
2778 PCI devices. If you choose "BIOS", the BIOS will be used,
2779 if you choose "Direct", the BIOS won't be used, and if you
2780 choose "MMConfig", then PCI Express MMCONFIG will be used.
2781 If you choose "Any", the kernel will try MMCONFIG, then the
2782 direct access method and falls back to the BIOS if that doesn't
2783 work. If unsure, go with the default, which is "Any".
2788 config PCI_GOMMCONFIG
2805 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2807 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2810 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2813 bool "Support mmconfig PCI config space access" if X86_64
2815 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2816 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2820 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2824 depends on PCI && XEN
2826 config MMCONF_FAM10H
2828 depends on X86_64 && PCI_MMCONFIG && ACPI
2830 config PCI_CNB20LE_QUIRK
2831 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2834 Read the PCI windows out of the CNB20LE host bridge. This allows
2835 PCI hotplug to work on systems with the CNB20LE chipset which do
2838 There's no public spec for this chipset, and this functionality
2839 is known to be incomplete.
2841 You should say N unless you know you need this.
2844 bool "ISA bus support on modern systems" if EXPERT
2846 Expose ISA bus device drivers and options available for selection and
2847 configuration. Enable this option if your target machine has an ISA
2848 bus. ISA is an older system, displaced by PCI and newer bus
2849 architectures -- if your target machine is modern, it probably does
2850 not have an ISA bus.
2854 # x86_64 have no ISA slots, but can have ISA-style DMA.
2856 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2859 Enables ISA-style DMA support for devices requiring such controllers.
2867 Find out whether you have ISA slots on your motherboard. ISA is the
2868 name of a bus system, i.e. the way the CPU talks to the other stuff
2869 inside your box. Other bus systems are PCI, EISA, MicroChannel
2870 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2871 newer boards don't support it. If you have ISA, say Y, otherwise N.
2874 tristate "NatSemi SCx200 support"
2876 This provides basic support for National Semiconductor's
2877 (now AMD's) Geode processors. The driver probes for the
2878 PCI-IDs of several on-chip devices, so its a good dependency
2879 for other scx200_* drivers.
2881 If compiled as a module, the driver is named scx200.
2883 config SCx200HR_TIMER
2884 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2888 This driver provides a clocksource built upon the on-chip
2889 27MHz high-resolution timer. Its also a workaround for
2890 NSC Geode SC-1100's buggy TSC, which loses time when the
2891 processor goes idle (as is done by the scheduler). The
2892 other workaround is idle=poll boot option.
2895 bool "One Laptop Per Child support"
2903 Add support for detecting the unique features of the OLPC
2907 bool "OLPC XO-1 Power Management"
2908 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2910 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2913 bool "OLPC XO-1 Real Time Clock"
2914 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2916 Add support for the XO-1 real time clock, which can be used as a
2917 programmable wakeup source.
2920 bool "OLPC XO-1 SCI extras"
2921 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2925 Add support for SCI-based features of the OLPC XO-1 laptop:
2926 - EC-driven system wakeups
2930 - AC adapter status updates
2931 - Battery status updates
2933 config OLPC_XO15_SCI
2934 bool "OLPC XO-1.5 SCI extras"
2935 depends on OLPC && ACPI
2938 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2939 - EC-driven system wakeups
2940 - AC adapter status updates
2941 - Battery status updates
2944 bool "PCEngines ALIX System Support (LED setup)"
2947 This option enables system support for the PCEngines ALIX.
2948 At present this just sets up LEDs for GPIO control on
2949 ALIX2/3/6 boards. However, other system specific setup should
2952 Note: You must still enable the drivers for GPIO and LED support
2953 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2955 Note: You have to set alix.force=1 for boards with Award BIOS.
2958 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2961 This option enables system support for the Soekris Engineering net5501.
2964 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2968 This option enables system support for the Traverse Technologies GEOS.
2971 bool "Technologic Systems TS-5500 platform support"
2973 select CHECK_SIGNATURE
2977 This option enables system support for the Technologic Systems TS-5500.
2983 depends on CPU_SUP_AMD && PCI
2987 menu "Binary Emulations"
2989 config IA32_EMULATION
2990 bool "IA32 Emulation"
2992 select ARCH_WANT_OLD_COMPAT_IPC
2994 select COMPAT_OLD_SIGACTION
2996 Include code to run legacy 32-bit programs under a
2997 64-bit kernel. You should likely turn this on, unless you're
2998 100% sure that you don't have any 32-bit programs left.
3001 bool "x32 ABI for 64-bit mode"
3003 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3004 # compressed debug sections to x86_x32 properly:
3005 # https://github.com/ClangBuiltLinux/linux/issues/514
3006 # https://github.com/ClangBuiltLinux/linux/issues/1141
3007 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3009 Include code to run binaries for the x32 native 32-bit ABI
3010 for 64-bit processors. An x32 process gets access to the
3011 full 64-bit register file and wide data path while leaving
3012 pointers at 32 bits for smaller memory footprint.
3016 depends on IA32_EMULATION || X86_32
3018 select OLD_SIGSUSPEND3
3022 depends on IA32_EMULATION || X86_X32_ABI
3024 config COMPAT_FOR_U64_ALIGNMENT
3030 config HAVE_ATOMIC_IOMAP
3034 source "arch/x86/kvm/Kconfig"
3036 source "arch/x86/Kconfig.assembler"