1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_SUPPORTS_PER_VMA_LOCK
31 select ARCH_USE_CMPXCHG_LOCKREF
32 select HAVE_ARCH_SOFT_DIRTY
33 select MODULES_USE_ELF_RELA
34 select NEED_DMA_MAP_STATE
36 select ARCH_HAS_ELFCORE_COMPAT
39 config FORCE_DYNAMIC_FTRACE
42 depends on FUNCTION_TRACER
45 We keep the static function tracing (!DYNAMIC_FTRACE) around
46 in order to test the non static function tracing in the
47 generic code, as other architectures still use it. But we
48 only need to keep it around for x86_64. No need to keep it
49 for x86_32. For x86_32, force DYNAMIC_FTRACE.
53 # ( Note that options that are marked 'if X86_64' could in principle be
54 # ported to 32-bit as well. )
59 # Note: keep this list sorted alphabetically
61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
63 select ARCH_32BIT_OFF_T if X86_32
64 select ARCH_CLOCKSOURCE_INIT
65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
72 select ARCH_HAS_CACHE_LINE_SIZE
73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
74 select ARCH_HAS_CPU_FINALIZE_INIT
75 select ARCH_HAS_CURRENT_STACK_POINTER
76 select ARCH_HAS_DEBUG_VIRTUAL
77 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
78 select ARCH_HAS_DEVMEM_IS_ALLOWED
79 select ARCH_HAS_EARLY_DEBUG if KGDB
80 select ARCH_HAS_ELF_RANDOMIZE
81 select ARCH_HAS_FAST_MULTIPLIER
82 select ARCH_HAS_FORTIFY_SOURCE
83 select ARCH_HAS_GCOV_PROFILE_ALL
84 select ARCH_HAS_KCOV if X86_64
85 select ARCH_HAS_MEM_ENCRYPT
86 select ARCH_HAS_MEMBARRIER_SYNC_CORE
87 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
88 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
89 select ARCH_HAS_PMEM_API if X86_64
90 select ARCH_HAS_PTE_DEVMAP if X86_64
91 select ARCH_HAS_PTE_SPECIAL
92 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
93 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
94 select ARCH_HAS_COPY_MC if X86_64
95 select ARCH_HAS_SET_MEMORY
96 select ARCH_HAS_SET_DIRECT_MAP
97 select ARCH_HAS_STRICT_KERNEL_RWX
98 select ARCH_HAS_STRICT_MODULE_RWX
99 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
100 select ARCH_HAS_SYSCALL_WRAPPER
101 select ARCH_HAS_UBSAN_SANITIZE_ALL
102 select ARCH_HAS_DEBUG_WX
103 select ARCH_HAS_ZONE_DMA_SET if EXPERT
104 select ARCH_HAVE_NMI_SAFE_CMPXCHG
105 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
106 select ARCH_MIGHT_HAVE_PC_PARPORT
107 select ARCH_MIGHT_HAVE_PC_SERIO
108 select ARCH_STACKWALK
109 select ARCH_SUPPORTS_ACPI
110 select ARCH_SUPPORTS_ATOMIC_RMW
111 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
112 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
113 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
114 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
115 select ARCH_SUPPORTS_CFI_CLANG if X86_64
116 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
117 select ARCH_SUPPORTS_LTO_CLANG
118 select ARCH_SUPPORTS_LTO_CLANG_THIN
119 select ARCH_USE_BUILTIN_BSWAP
120 select ARCH_USE_MEMTEST
121 select ARCH_USE_QUEUED_RWLOCKS
122 select ARCH_USE_QUEUED_SPINLOCKS
123 select ARCH_USE_SYM_ANNOTATIONS
124 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
125 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
126 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
127 select ARCH_WANTS_NO_INSTR
128 select ARCH_WANT_GENERAL_HUGETLB
129 select ARCH_WANT_HUGE_PMD_SHARE
130 select ARCH_WANT_LD_ORPHAN_WARN
131 select ARCH_WANT_OPTIMIZE_VMEMMAP if X86_64
132 select ARCH_WANTS_THP_SWAP if X86_64
133 select ARCH_HAS_PARANOID_L1D_FLUSH
134 select BUILDTIME_TABLE_SORT
136 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
137 select CLOCKSOURCE_WATCHDOG
138 # Word-size accesses may read uninitialized data past the trailing \0
139 # in strings and cause false KMSAN reports.
140 select DCACHE_WORD_ACCESS if !KMSAN
141 select DYNAMIC_SIGFRAME
142 select EDAC_ATOMIC_SCRUB
144 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
145 select GENERIC_CLOCKEVENTS_MIN_ADJUST
146 select GENERIC_CMOS_UPDATE
147 select GENERIC_CPU_AUTOPROBE
148 select GENERIC_CPU_VULNERABILITIES
149 select GENERIC_EARLY_IOREMAP
152 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
153 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
154 select GENERIC_IRQ_MIGRATION if SMP
155 select GENERIC_IRQ_PROBE
156 select GENERIC_IRQ_RESERVATION_MODE
157 select GENERIC_IRQ_SHOW
158 select GENERIC_PENDING_IRQ if SMP
159 select GENERIC_PTDUMP
160 select GENERIC_SMP_IDLE_THREAD
161 select GENERIC_TIME_VSYSCALL
162 select GENERIC_GETTIMEOFDAY
163 select GENERIC_VDSO_TIME_NS
164 select GUP_GET_PXX_LOW_HIGH if X86_PAE
165 select HARDIRQS_SW_RESEND
166 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
168 select HAVE_ACPI_APEI if ACPI
169 select HAVE_ACPI_APEI_NMI if ACPI
170 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
171 select HAVE_ARCH_AUDITSYSCALL
172 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
173 select HAVE_ARCH_HUGE_VMALLOC if X86_64
174 select HAVE_ARCH_JUMP_LABEL
175 select HAVE_ARCH_JUMP_LABEL_RELATIVE
176 select HAVE_ARCH_KASAN if X86_64
177 select HAVE_ARCH_KASAN_VMALLOC if X86_64
178 select HAVE_ARCH_KFENCE
179 select HAVE_ARCH_KMSAN if X86_64
180 select HAVE_ARCH_KGDB
181 select HAVE_ARCH_MMAP_RND_BITS if MMU
182 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
183 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
184 select HAVE_ARCH_PREL32_RELOCATIONS
185 select HAVE_ARCH_SECCOMP_FILTER
186 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
187 select HAVE_ARCH_STACKLEAK
188 select HAVE_ARCH_TRACEHOOK
189 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
190 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
191 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
192 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
193 select HAVE_ARCH_VMAP_STACK if X86_64
194 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
195 select HAVE_ARCH_WITHIN_STACK_FRAMES
196 select HAVE_ASM_MODVERSIONS
197 select HAVE_CMPXCHG_DOUBLE
198 select HAVE_CMPXCHG_LOCAL
199 select HAVE_CONTEXT_TRACKING_USER if X86_64
200 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
201 select HAVE_C_RECORDMCOUNT
202 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
203 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
204 select HAVE_BUILDTIME_MCOUNT_SORT
205 select HAVE_DEBUG_KMEMLEAK
206 select HAVE_DMA_CONTIGUOUS
207 select HAVE_DYNAMIC_FTRACE
208 select HAVE_DYNAMIC_FTRACE_WITH_REGS
209 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
210 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
211 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
212 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
214 select HAVE_EFFICIENT_UNALIGNED_ACCESS
216 select HAVE_EXIT_THREAD
218 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
219 select HAVE_FTRACE_MCOUNT_RECORD
220 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
221 select HAVE_FUNCTION_TRACER
222 select HAVE_GCC_PLUGINS
223 select HAVE_HW_BREAKPOINT
224 select HAVE_IOREMAP_PROT
225 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
226 select HAVE_IRQ_TIME_ACCOUNTING
227 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
228 select HAVE_KERNEL_BZIP2
229 select HAVE_KERNEL_GZIP
230 select HAVE_KERNEL_LZ4
231 select HAVE_KERNEL_LZMA
232 select HAVE_KERNEL_LZO
233 select HAVE_KERNEL_XZ
234 select HAVE_KERNEL_ZSTD
236 select HAVE_KPROBES_ON_FTRACE
237 select HAVE_FUNCTION_ERROR_INJECTION
238 select HAVE_KRETPROBES
241 select HAVE_LIVEPATCH if X86_64
242 select HAVE_MIXED_BREAKPOINTS_REGS
243 select HAVE_MOD_ARCH_SPECIFIC
246 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
248 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
249 select HAVE_OBJTOOL if X86_64
250 select HAVE_OPTPROBES
251 select HAVE_PCSPKR_PLATFORM
252 select HAVE_PERF_EVENTS
253 select HAVE_PERF_EVENTS_NMI
254 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
256 select HAVE_PERF_REGS
257 select HAVE_PERF_USER_STACK_DUMP
258 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
259 select MMU_GATHER_MERGE_VMAS
260 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
261 select HAVE_REGS_AND_STACK_ACCESS_API
262 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
263 select HAVE_FUNCTION_ARG_ACCESS_API
264 select HAVE_SETUP_PER_CPU_AREA
265 select HAVE_SOFTIRQ_ON_OWN_STACK
266 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
267 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
268 select HAVE_STATIC_CALL
269 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
270 select HAVE_PREEMPT_DYNAMIC_CALL
272 select HAVE_RUST if X86_64
273 select HAVE_SYSCALL_TRACEPOINTS
274 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
275 select HAVE_UNSTABLE_SCHED_CLOCK
276 select HAVE_USER_RETURN_NOTIFIER
277 select HAVE_GENERIC_VDSO
278 select HOTPLUG_PARALLEL if SMP && X86_64
279 select HOTPLUG_SMT if SMP
280 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
281 select IRQ_FORCED_THREADING
282 select NEED_PER_CPU_EMBED_FIRST_CHUNK
283 select NEED_PER_CPU_PAGE_FIRST_CHUNK
284 select NEED_SG_DMA_LENGTH
285 select PCI_DOMAINS if PCI
286 select PCI_LOCKLESS_CONFIG if PCI
289 select RTC_MC146818_LIB
291 select SYSCTL_EXCEPTION_TRACE
292 select THREAD_INFO_IN_TASK
293 select TRACE_IRQFLAGS_SUPPORT
294 select TRACE_IRQFLAGS_NMI_SUPPORT
295 select USER_STACKTRACE_SUPPORT
296 select HAVE_ARCH_KCSAN if X86_64
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.
447 bool "Support x2apic"
448 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
450 This enables x2apic support on CPUs that have this feature.
452 This allows 32-bit apic IDs (so it can support very large systems),
453 and accesses the local apic via MSRs not via mmio.
455 Some Intel systems circa 2022 and later are locked into x2APIC mode
456 and can not fall back to the legacy APIC modes if SGX or TDX are
457 enabled in the BIOS. They will boot with very reduced functionality
458 without enabling this option.
460 If you don't know what to do here, say N.
463 bool "Enable MPS table" if ACPI
465 depends on X86_LOCAL_APIC
467 For old smp systems that do not have proper acpi support. Newer systems
468 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
472 depends on X86_GOLDFISH
474 config X86_CPU_RESCTRL
475 bool "x86 CPU resource control support"
476 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
478 select PROC_CPU_RESCTRL if PROC_FS
480 Enable x86 CPU resource control support.
482 Provide support for the allocation and monitoring of system resources
485 Intel calls this Intel Resource Director Technology
486 (Intel(R) RDT). More information about RDT can be found in the
487 Intel x86 Architecture Software Developer Manual.
489 AMD calls this AMD Platform Quality of Service (AMD QoS).
490 More information about AMD QoS can be found in the AMD64 Technology
491 Platform Quality of Service Extensions manual.
497 bool "Support for big SMP systems with more than 8 CPUs"
500 This option is needed for the systems that have more than 8 CPUs.
502 config X86_EXTENDED_PLATFORM
503 bool "Support for extended (non-PC) x86 platforms"
506 If you disable this option then the kernel will only support
507 standard PC platforms. (which covers the vast majority of
510 If you enable this option then you'll be able to select support
511 for the following (non-PC) 32 bit x86 platforms:
512 Goldfish (Android emulator)
515 SGI 320/540 (Visual Workstation)
516 STA2X11-based (e.g. Northville)
517 Moorestown MID devices
519 If you have one of these systems, or if you want to build a
520 generic distribution kernel, say Y here - otherwise say N.
524 config X86_EXTENDED_PLATFORM
525 bool "Support for extended (non-PC) x86 platforms"
528 If you disable this option then the kernel will only support
529 standard PC platforms. (which covers the vast majority of
532 If you enable this option then you'll be able to select support
533 for the following (non-PC) 64 bit x86 platforms:
538 If you have one of these systems, or if you want to build a
539 generic distribution kernel, say Y here - otherwise say N.
541 # This is an alphabetically sorted list of 64 bit extended platforms
542 # Please maintain the alphabetic order if and when there are additions
544 bool "Numascale NumaChip"
546 depends on X86_EXTENDED_PLATFORM
549 depends on X86_X2APIC
550 depends on PCI_MMCONFIG
552 Adds support for Numascale NumaChip large-SMP systems. Needed to
553 enable more than ~168 cores.
554 If you don't have one of these, you should say N here.
558 select HYPERVISOR_GUEST
560 depends on X86_64 && PCI
561 depends on X86_EXTENDED_PLATFORM
564 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
565 supposed to run on these EM64T-based machines. Only choose this option
566 if you have one of these machines.
569 bool "SGI Ultraviolet"
571 depends on X86_EXTENDED_PLATFORM
574 depends on KEXEC_CORE
575 depends on X86_X2APIC
578 This option is needed in order to support SGI Ultraviolet systems.
579 If you don't have one of these, you should say N here.
581 # Following is an alphabetically sorted list of 32 bit extended platforms
582 # Please maintain the alphabetic order if and when there are additions
585 bool "Goldfish (Virtual Platform)"
586 depends on X86_EXTENDED_PLATFORM
588 Enable support for the Goldfish virtual platform used primarily
589 for Android development. Unless you are building for the Android
590 Goldfish emulator say N here.
593 bool "CE4100 TV platform"
595 depends on PCI_GODIRECT
596 depends on X86_IO_APIC
598 depends on X86_EXTENDED_PLATFORM
599 select X86_REBOOTFIXUPS
601 select OF_EARLY_FLATTREE
603 Select for the Intel CE media processor (CE4100) SOC.
604 This option compiles in support for the CE4100 SOC for settop
605 boxes and media devices.
608 bool "Intel MID platform support"
609 depends on X86_EXTENDED_PLATFORM
610 depends on X86_PLATFORM_DEVICES
612 depends on X86_64 || (PCI_GOANY && X86_32)
613 depends on X86_IO_APIC
618 Select to build a kernel capable of supporting Intel MID (Mobile
619 Internet Device) platform systems which do not have the PCI legacy
620 interfaces. If you are building for a PC class system say N here.
622 Intel MID platforms are based on an Intel processor and chipset which
623 consume less power than most of the x86 derivatives.
625 config X86_INTEL_QUARK
626 bool "Intel Quark platform support"
628 depends on X86_EXTENDED_PLATFORM
629 depends on X86_PLATFORM_DEVICES
633 depends on X86_IO_APIC
638 Select to include support for Quark X1000 SoC.
639 Say Y here if you have a Quark based system such as the Arduino
640 compatible Intel Galileo.
642 config X86_INTEL_LPSS
643 bool "Intel Low Power Subsystem Support"
644 depends on X86 && ACPI && PCI
649 Select to build support for Intel Low Power Subsystem such as
650 found on Intel Lynxpoint PCH. Selecting this option enables
651 things like clock tree (common clock framework) and pincontrol
652 which are needed by the LPSS peripheral drivers.
654 config X86_AMD_PLATFORM_DEVICE
655 bool "AMD ACPI2Platform devices support"
660 Select to interpret AMD specific ACPI device to platform device
661 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
662 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
663 implemented under PINCTRL subsystem.
666 tristate "Intel SoC IOSF Sideband support for SoC platforms"
669 This option enables sideband register access support for Intel SoC
670 platforms. On these platforms the IOSF sideband is used in lieu of
671 MSR's for some register accesses, mostly but not limited to thermal
672 and power. Drivers may query the availability of this device to
673 determine if they need the sideband in order to work on these
674 platforms. The sideband is available on the following SoC products.
675 This list is not meant to be exclusive.
680 You should say Y if you are running a kernel on one of these SoC's.
682 config IOSF_MBI_DEBUG
683 bool "Enable IOSF sideband access through debugfs"
684 depends on IOSF_MBI && DEBUG_FS
686 Select this option to expose the IOSF sideband access registers (MCR,
687 MDR, MCRX) through debugfs to write and read register information from
688 different units on the SoC. This is most useful for obtaining device
689 state information for debug and analysis. As this is a general access
690 mechanism, users of this option would have specific knowledge of the
691 device they want to access.
693 If you don't require the option or are in doubt, say N.
696 bool "RDC R-321x SoC"
698 depends on X86_EXTENDED_PLATFORM
700 select X86_REBOOTFIXUPS
702 This option is needed for RDC R-321x system-on-chip, also known
704 If you don't have one of these chips, you should say N here.
706 config X86_32_NON_STANDARD
707 bool "Support non-standard 32-bit SMP architectures"
708 depends on X86_32 && SMP
709 depends on X86_EXTENDED_PLATFORM
711 This option compiles in the bigsmp and STA2X11 default
712 subarchitectures. It is intended for a generic binary
713 kernel. If you select them all, kernel will probe it one by
714 one and will fallback to default.
716 # Alphabetically sorted list of Non standard 32 bit platforms
718 config X86_SUPPORTS_MEMORY_FAILURE
720 # MCE code calls memory_failure():
722 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
723 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
724 depends on X86_64 || !SPARSEMEM
725 select ARCH_SUPPORTS_MEMORY_FAILURE
728 bool "STA2X11 Companion Chip Support"
729 depends on X86_32_NON_STANDARD && PCI
734 This adds support for boards based on the STA2X11 IO-Hub,
735 a.k.a. "ConneXt". The chip is used in place of the standard
736 PC chipset, so all "standard" peripherals are missing. If this
737 option is selected the kernel will still be able to boot on
738 standard PC machines.
741 tristate "Eurobraille/Iris poweroff module"
744 The Iris machines from EuroBraille do not have APM or ACPI support
745 to shut themselves down properly. A special I/O sequence is
746 needed to do so, which is what this module does at
749 This is only for Iris machines from EuroBraille.
753 config SCHED_OMIT_FRAME_POINTER
755 prompt "Single-depth WCHAN output"
758 Calculate simpler /proc/<PID>/wchan values. If this option
759 is disabled then wchan values will recurse back to the
760 caller function. This provides more accurate wchan values,
761 at the expense of slightly more scheduling overhead.
763 If in doubt, say "Y".
765 menuconfig HYPERVISOR_GUEST
766 bool "Linux guest support"
768 Say Y here to enable options for running Linux under various hyper-
769 visors. This option enables basic hypervisor detection and platform
772 If you say N, all options in this submenu will be skipped and
773 disabled, and Linux guest support won't be built in.
778 bool "Enable paravirtualization code"
779 depends on HAVE_STATIC_CALL
781 This changes the kernel so it can modify itself when it is run
782 under a hypervisor, potentially improving performance significantly
783 over full virtualization. However, when run without a hypervisor
784 the kernel is theoretically slower and slightly larger.
789 config PARAVIRT_DEBUG
790 bool "paravirt-ops debugging"
791 depends on PARAVIRT && DEBUG_KERNEL
793 Enable to debug paravirt_ops internals. Specifically, BUG if
794 a paravirt_op is missing when it is called.
796 config PARAVIRT_SPINLOCKS
797 bool "Paravirtualization layer for spinlocks"
798 depends on PARAVIRT && SMP
800 Paravirtualized spinlocks allow a pvops backend to replace the
801 spinlock implementation with something virtualization-friendly
802 (for example, block the virtual CPU rather than spinning).
804 It has a minimal impact on native kernels and gives a nice performance
805 benefit on paravirtualized KVM / Xen kernels.
807 If you are unsure how to answer this question, answer Y.
809 config X86_HV_CALLBACK_VECTOR
812 source "arch/x86/xen/Kconfig"
815 bool "KVM Guest support (including kvmclock)"
817 select PARAVIRT_CLOCK
818 select ARCH_CPUIDLE_HALTPOLL
819 select X86_HV_CALLBACK_VECTOR
822 This option enables various optimizations for running under the KVM
823 hypervisor. It includes a paravirtualized clock, so that instead
824 of relying on a PIT (or probably other) emulation by the
825 underlying device model, the host provides the guest with
826 timing infrastructure such as time of day, and system time
828 config ARCH_CPUIDLE_HALTPOLL
830 prompt "Disable host haltpoll when loading haltpoll driver"
832 If virtualized under KVM, disable host haltpoll.
835 bool "Support for running PVH guests"
837 This option enables the PVH entry point for guest virtual machines
838 as specified in the x86/HVM direct boot ABI.
840 config PARAVIRT_TIME_ACCOUNTING
841 bool "Paravirtual steal time accounting"
844 Select this option to enable fine granularity task steal time
845 accounting. Time spent executing other tasks in parallel with
846 the current vCPU is discounted from the vCPU power. To account for
847 that, there can be a small performance impact.
849 If in doubt, say N here.
851 config PARAVIRT_CLOCK
854 config JAILHOUSE_GUEST
855 bool "Jailhouse non-root cell support"
856 depends on X86_64 && PCI
859 This option allows to run Linux as guest in a Jailhouse non-root
860 cell. You can leave this option disabled if you only want to start
861 Jailhouse and run Linux afterwards in the root cell.
864 bool "ACRN Guest support"
866 select X86_HV_CALLBACK_VECTOR
868 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
869 a flexible, lightweight reference open-source hypervisor, built with
870 real-time and safety-criticality in mind. It is built for embedded
871 IOT with small footprint and real-time features. More details can be
872 found in https://projectacrn.org/.
874 config INTEL_TDX_GUEST
875 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
876 depends on X86_64 && CPU_SUP_INTEL
877 depends on X86_X2APIC
879 select ARCH_HAS_CC_PLATFORM
880 select X86_MEM_ENCRYPT
882 select UNACCEPTED_MEMORY
884 Support running as a guest under Intel TDX. Without this support,
885 the guest kernel can not boot or run under TDX.
886 TDX includes memory encryption and integrity capabilities
887 which protect the confidentiality and integrity of guest
888 memory contents and CPU state. TDX guests are protected from
889 some attacks from the VMM.
891 endif # HYPERVISOR_GUEST
893 source "arch/x86/Kconfig.cpu"
897 prompt "HPET Timer Support" if X86_32
899 Use the IA-PC HPET (High Precision Event Timer) to manage
900 time in preference to the PIT and RTC, if a HPET is
902 HPET is the next generation timer replacing legacy 8254s.
903 The HPET provides a stable time base on SMP
904 systems, unlike the TSC, but it is more expensive to access,
905 as it is off-chip. The interface used is documented
906 in the HPET spec, revision 1.
908 You can safely choose Y here. However, HPET will only be
909 activated if the platform and the BIOS support this feature.
910 Otherwise the 8254 will be used for timing services.
912 Choose N to continue using the legacy 8254 timer.
914 config HPET_EMULATE_RTC
916 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
918 # Mark as expert because too many people got it wrong.
919 # The code disables itself when not needed.
922 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
923 bool "Enable DMI scanning" if EXPERT
925 Enabled scanning of DMI to identify machine quirks. Say Y
926 here unless you have verified that your setup is not
927 affected by entries in the DMI blacklist. Required by PNP
931 bool "Old AMD GART IOMMU support"
935 depends on X86_64 && PCI && AMD_NB
937 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
938 GART based hardware IOMMUs.
940 The GART supports full DMA access for devices with 32-bit access
941 limitations, on systems with more than 3 GB. This is usually needed
942 for USB, sound, many IDE/SATA chipsets and some other devices.
944 Newer systems typically have a modern AMD IOMMU, supported via
945 the CONFIG_AMD_IOMMU=y config option.
947 In normal configurations this driver is only active when needed:
948 there's more than 3 GB of memory and the system contains a
949 32-bit limited device.
953 config BOOT_VESA_SUPPORT
956 If true, at least one selected framebuffer driver can take advantage
957 of VESA video modes set at an early boot stage via the vga= parameter.
960 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
961 depends on X86_64 && SMP && DEBUG_KERNEL
962 select CPUMASK_OFFSTACK
964 Enable maximum number of CPUS and NUMA Nodes for this architecture.
968 # The maximum number of CPUs supported:
970 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
971 # and which can be configured interactively in the
972 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
974 # The ranges are different on 32-bit and 64-bit kernels, depending on
975 # hardware capabilities and scalability features of the kernel.
977 # ( If MAXSMP is enabled we just use the highest possible value and disable
978 # interactive configuration. )
981 config NR_CPUS_RANGE_BEGIN
983 default NR_CPUS_RANGE_END if MAXSMP
987 config NR_CPUS_RANGE_END
990 default 64 if SMP && X86_BIGSMP
991 default 8 if SMP && !X86_BIGSMP
994 config NR_CPUS_RANGE_END
997 default 8192 if SMP && CPUMASK_OFFSTACK
998 default 512 if SMP && !CPUMASK_OFFSTACK
1001 config NR_CPUS_DEFAULT
1004 default 32 if X86_BIGSMP
1008 config NR_CPUS_DEFAULT
1011 default 8192 if MAXSMP
1016 int "Maximum number of CPUs" if SMP && !MAXSMP
1017 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1018 default NR_CPUS_DEFAULT
1020 This allows you to specify the maximum number of CPUs which this
1021 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1022 supported value is 8192, otherwise the maximum value is 512. The
1023 minimum value which makes sense is 2.
1025 This is purely to save memory: each supported CPU adds about 8KB
1026 to the kernel image.
1028 config SCHED_CLUSTER
1029 bool "Cluster scheduler support"
1033 Cluster scheduler support improves the CPU scheduler's decision
1034 making when dealing with machines that have clusters of CPUs.
1035 Cluster usually means a couple of CPUs which are placed closely
1036 by sharing mid-level caches, last-level cache tags or internal
1044 prompt "Multi-core scheduler support"
1047 Multi-core scheduler support improves the CPU scheduler's decision
1048 making when dealing with multi-core CPU chips at a cost of slightly
1049 increased overhead in some places. If unsure say N here.
1051 config SCHED_MC_PRIO
1052 bool "CPU core priorities scheduler support"
1053 depends on SCHED_MC && CPU_SUP_INTEL
1054 select X86_INTEL_PSTATE
1058 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1059 core ordering determined at manufacturing time, which allows
1060 certain cores to reach higher turbo frequencies (when running
1061 single threaded workloads) than others.
1063 Enabling this kernel feature teaches the scheduler about
1064 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1065 scheduler's CPU selection logic accordingly, so that higher
1066 overall system performance can be achieved.
1068 This feature will have no effect on CPUs without this feature.
1070 If unsure say Y here.
1074 depends on !SMP && X86_LOCAL_APIC
1077 bool "Local APIC support on uniprocessors" if !PCI_MSI
1079 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1081 A local APIC (Advanced Programmable Interrupt Controller) is an
1082 integrated interrupt controller in the CPU. If you have a single-CPU
1083 system which has a processor with a local APIC, you can say Y here to
1084 enable and use it. If you say Y here even though your machine doesn't
1085 have a local APIC, then the kernel will still run with no slowdown at
1086 all. The local APIC supports CPU-generated self-interrupts (timer,
1087 performance counters), and the NMI watchdog which detects hard
1090 config X86_UP_IOAPIC
1091 bool "IO-APIC support on uniprocessors"
1092 depends on X86_UP_APIC
1094 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1095 SMP-capable replacement for PC-style interrupt controllers. Most
1096 SMP systems and many recent uniprocessor systems have one.
1098 If you have a single-CPU system with an IO-APIC, you can say Y here
1099 to use it. If you say Y here even though your machine doesn't have
1100 an IO-APIC, then the kernel will still run with no slowdown at all.
1102 config X86_LOCAL_APIC
1104 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1105 select IRQ_DOMAIN_HIERARCHY
1109 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1111 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1112 bool "Reroute for broken boot IRQs"
1113 depends on X86_IO_APIC
1115 This option enables a workaround that fixes a source of
1116 spurious interrupts. This is recommended when threaded
1117 interrupt handling is used on systems where the generation of
1118 superfluous "boot interrupts" cannot be disabled.
1120 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1121 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1122 kernel does during interrupt handling). On chipsets where this
1123 boot IRQ generation cannot be disabled, this workaround keeps
1124 the original IRQ line masked so that only the equivalent "boot
1125 IRQ" is delivered to the CPUs. The workaround also tells the
1126 kernel to set up the IRQ handler on the boot IRQ line. In this
1127 way only one interrupt is delivered to the kernel. Otherwise
1128 the spurious second interrupt may cause the kernel to bring
1129 down (vital) interrupt lines.
1131 Only affects "broken" chipsets. Interrupt sharing may be
1132 increased on these systems.
1135 bool "Machine Check / overheating reporting"
1136 select GENERIC_ALLOCATOR
1139 Machine Check support allows the processor to notify the
1140 kernel if it detects a problem (e.g. overheating, data corruption).
1141 The action the kernel takes depends on the severity of the problem,
1142 ranging from warning messages to halting the machine.
1144 config X86_MCELOG_LEGACY
1145 bool "Support for deprecated /dev/mcelog character device"
1148 Enable support for /dev/mcelog which is needed by the old mcelog
1149 userspace logging daemon. Consider switching to the new generation
1152 config X86_MCE_INTEL
1154 prompt "Intel MCE features"
1155 depends on X86_MCE && X86_LOCAL_APIC
1157 Additional support for intel specific MCE features such as
1158 the thermal monitor.
1162 prompt "AMD MCE features"
1163 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1165 Additional support for AMD specific MCE features such as
1166 the DRAM Error Threshold.
1168 config X86_ANCIENT_MCE
1169 bool "Support for old Pentium 5 / WinChip machine checks"
1170 depends on X86_32 && X86_MCE
1172 Include support for machine check handling on old Pentium 5 or WinChip
1173 systems. These typically need to be enabled explicitly on the command
1176 config X86_MCE_THRESHOLD
1177 depends on X86_MCE_AMD || X86_MCE_INTEL
1180 config X86_MCE_INJECT
1181 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1182 tristate "Machine check injector support"
1184 Provide support for injecting machine checks for testing purposes.
1185 If you don't know what a machine check is and you don't do kernel
1186 QA it is safe to say n.
1188 source "arch/x86/events/Kconfig"
1190 config X86_LEGACY_VM86
1191 bool "Legacy VM86 support"
1194 This option allows user programs to put the CPU into V8086
1195 mode, which is an 80286-era approximation of 16-bit real mode.
1197 Some very old versions of X and/or vbetool require this option
1198 for user mode setting. Similarly, DOSEMU will use it if
1199 available to accelerate real mode DOS programs. However, any
1200 recent version of DOSEMU, X, or vbetool should be fully
1201 functional even without kernel VM86 support, as they will all
1202 fall back to software emulation. Nevertheless, if you are using
1203 a 16-bit DOS program where 16-bit performance matters, vm86
1204 mode might be faster than emulation and you might want to
1207 Note that any app that works on a 64-bit kernel is unlikely to
1208 need this option, as 64-bit kernels don't, and can't, support
1209 V8086 mode. This option is also unrelated to 16-bit protected
1210 mode and is not needed to run most 16-bit programs under Wine.
1212 Enabling this option increases the complexity of the kernel
1213 and slows down exception handling a tiny bit.
1215 If unsure, say N here.
1219 default X86_LEGACY_VM86
1222 bool "Enable support for 16-bit segments" if EXPERT
1224 depends on MODIFY_LDT_SYSCALL
1226 This option is required by programs like Wine to run 16-bit
1227 protected mode legacy code on x86 processors. Disabling
1228 this option saves about 300 bytes on i386, or around 6K text
1229 plus 16K runtime memory on x86-64,
1233 depends on X86_16BIT && X86_32
1237 depends on X86_16BIT && X86_64
1239 config X86_VSYSCALL_EMULATION
1240 bool "Enable vsyscall emulation" if EXPERT
1244 This enables emulation of the legacy vsyscall page. Disabling
1245 it is roughly equivalent to booting with vsyscall=none, except
1246 that it will also disable the helpful warning if a program
1247 tries to use a vsyscall. With this option set to N, offending
1248 programs will just segfault, citing addresses of the form
1251 This option is required by many programs built before 2013, and
1252 care should be used even with newer programs if set to N.
1254 Disabling this option saves about 7K of kernel size and
1255 possibly 4K of additional runtime pagetable memory.
1257 config X86_IOPL_IOPERM
1258 bool "IOPERM and IOPL Emulation"
1261 This enables the ioperm() and iopl() syscalls which are necessary
1262 for legacy applications.
1264 Legacy IOPL support is an overbroad mechanism which allows user
1265 space aside of accessing all 65536 I/O ports also to disable
1266 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1267 capabilities and permission from potentially active security
1270 The emulation restricts the functionality of the syscall to
1271 only allowing the full range I/O port access, but prevents the
1272 ability to disable interrupts from user space which would be
1273 granted if the hardware IOPL mechanism would be used.
1276 tristate "Toshiba Laptop support"
1279 This adds a driver to safely access the System Management Mode of
1280 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1281 not work on models with a Phoenix BIOS. The System Management Mode
1282 is used to set the BIOS and power saving options on Toshiba portables.
1284 For information on utilities to make use of this driver see the
1285 Toshiba Linux utilities web site at:
1286 <http://www.buzzard.org.uk/toshiba/>.
1288 Say Y if you intend to run this kernel on a Toshiba portable.
1291 config X86_REBOOTFIXUPS
1292 bool "Enable X86 board specific fixups for reboot"
1295 This enables chipset and/or board specific fixups to be done
1296 in order to get reboot to work correctly. This is only needed on
1297 some combinations of hardware and BIOS. The symptom, for which
1298 this config is intended, is when reboot ends with a stalled/hung
1301 Currently, the only fixup is for the Geode machines using
1302 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1304 Say Y if you want to enable the fixup. Currently, it's safe to
1305 enable this option even if you don't need it.
1309 bool "CPU microcode loading support"
1311 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1313 If you say Y here, you will be able to update the microcode on
1314 Intel and AMD processors. The Intel support is for the IA32 family,
1315 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1316 AMD support is for families 0x10 and later. You will obviously need
1317 the actual microcode binary data itself which is not shipped with
1320 The preferred method to load microcode from a detached initrd is described
1321 in Documentation/arch/x86/microcode.rst. For that you need to enable
1322 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1323 initrd for microcode blobs.
1325 In addition, you can build the microcode into the kernel. For that you
1326 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1329 config MICROCODE_INTEL
1330 bool "Intel microcode loading support"
1331 depends on CPU_SUP_INTEL && MICROCODE
1334 This options enables microcode patch loading support for Intel
1337 For the current Intel microcode data package go to
1338 <https://downloadcenter.intel.com> and search for
1339 'Linux Processor Microcode Data File'.
1341 config MICROCODE_AMD
1342 bool "AMD microcode loading support"
1343 depends on CPU_SUP_AMD && MICROCODE
1345 If you select this option, microcode patch loading support for AMD
1346 processors will be enabled.
1348 config MICROCODE_LATE_LOADING
1349 bool "Late microcode loading (DANGEROUS)"
1351 depends on MICROCODE
1353 Loading microcode late, when the system is up and executing instructions
1354 is a tricky business and should be avoided if possible. Just the sequence
1355 of synchronizing all cores and SMT threads is one fragile dance which does
1356 not guarantee that cores might not softlock after the loading. Therefore,
1357 use this at your own risk. Late loading taints the kernel too.
1360 tristate "/dev/cpu/*/msr - Model-specific register support"
1362 This device gives privileged processes access to the x86
1363 Model-Specific Registers (MSRs). It is a character device with
1364 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1365 MSR accesses are directed to a specific CPU on multi-processor
1369 tristate "/dev/cpu/*/cpuid - CPU information support"
1371 This device gives processes access to the x86 CPUID instruction to
1372 be executed on a specific processor. It is a character device
1373 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1377 prompt "High Memory Support"
1384 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1385 However, the address space of 32-bit x86 processors is only 4
1386 Gigabytes large. That means that, if you have a large amount of
1387 physical memory, not all of it can be "permanently mapped" by the
1388 kernel. The physical memory that's not permanently mapped is called
1391 If you are compiling a kernel which will never run on a machine with
1392 more than 1 Gigabyte total physical RAM, answer "off" here (default
1393 choice and suitable for most users). This will result in a "3GB/1GB"
1394 split: 3GB are mapped so that each process sees a 3GB virtual memory
1395 space and the remaining part of the 4GB virtual memory space is used
1396 by the kernel to permanently map as much physical memory as
1399 If the machine has between 1 and 4 Gigabytes physical RAM, then
1402 If more than 4 Gigabytes is used then answer "64GB" here. This
1403 selection turns Intel PAE (Physical Address Extension) mode on.
1404 PAE implements 3-level paging on IA32 processors. PAE is fully
1405 supported by Linux, PAE mode is implemented on all recent Intel
1406 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1407 then the kernel will not boot on CPUs that don't support PAE!
1409 The actual amount of total physical memory will either be
1410 auto detected or can be forced by using a kernel command line option
1411 such as "mem=256M". (Try "man bootparam" or see the documentation of
1412 your boot loader (lilo or loadlin) about how to pass options to the
1413 kernel at boot time.)
1415 If unsure, say "off".
1420 Select this if you have a 32-bit processor and between 1 and 4
1421 gigabytes of physical RAM.
1425 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1428 Select this if you have a 32-bit processor and more than 4
1429 gigabytes of physical RAM.
1434 prompt "Memory split" if EXPERT
1438 Select the desired split between kernel and user memory.
1440 If the address range available to the kernel is less than the
1441 physical memory installed, the remaining memory will be available
1442 as "high memory". Accessing high memory is a little more costly
1443 than low memory, as it needs to be mapped into the kernel first.
1444 Note that increasing the kernel address space limits the range
1445 available to user programs, making the address space there
1446 tighter. Selecting anything other than the default 3G/1G split
1447 will also likely make your kernel incompatible with binary-only
1450 If you are not absolutely sure what you are doing, leave this
1454 bool "3G/1G user/kernel split"
1455 config VMSPLIT_3G_OPT
1457 bool "3G/1G user/kernel split (for full 1G low memory)"
1459 bool "2G/2G user/kernel split"
1460 config VMSPLIT_2G_OPT
1462 bool "2G/2G user/kernel split (for full 2G low memory)"
1464 bool "1G/3G user/kernel split"
1469 default 0xB0000000 if VMSPLIT_3G_OPT
1470 default 0x80000000 if VMSPLIT_2G
1471 default 0x78000000 if VMSPLIT_2G_OPT
1472 default 0x40000000 if VMSPLIT_1G
1478 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1481 bool "PAE (Physical Address Extension) Support"
1482 depends on X86_32 && !HIGHMEM4G
1483 select PHYS_ADDR_T_64BIT
1486 PAE is required for NX support, and furthermore enables
1487 larger swapspace support for non-overcommit purposes. It
1488 has the cost of more pagetable lookup overhead, and also
1489 consumes more pagetable space per process.
1492 bool "Enable 5-level page tables support"
1494 select DYNAMIC_MEMORY_LAYOUT
1495 select SPARSEMEM_VMEMMAP
1498 5-level paging enables access to larger address space:
1499 up to 128 PiB of virtual address space and 4 PiB of
1500 physical address space.
1502 It will be supported by future Intel CPUs.
1504 A kernel with the option enabled can be booted on machines that
1505 support 4- or 5-level paging.
1507 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1512 config X86_DIRECT_GBPAGES
1516 Certain kernel features effectively disable kernel
1517 linear 1 GB mappings (even if the CPU otherwise
1518 supports them), so don't confuse the user by printing
1519 that we have them enabled.
1521 config X86_CPA_STATISTICS
1522 bool "Enable statistic for Change Page Attribute"
1525 Expose statistics about the Change Page Attribute mechanism, which
1526 helps to determine the effectiveness of preserving large and huge
1527 page mappings when mapping protections are changed.
1529 config X86_MEM_ENCRYPT
1530 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1531 select DYNAMIC_PHYSICAL_MASK
1534 config AMD_MEM_ENCRYPT
1535 bool "AMD Secure Memory Encryption (SME) support"
1536 depends on X86_64 && CPU_SUP_AMD
1538 select DMA_COHERENT_POOL
1539 select ARCH_USE_MEMREMAP_PROT
1540 select INSTRUCTION_DECODER
1541 select ARCH_HAS_CC_PLATFORM
1542 select X86_MEM_ENCRYPT
1543 select UNACCEPTED_MEMORY
1545 Say yes to enable support for the encryption of system memory.
1546 This requires an AMD processor that supports Secure Memory
1549 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1550 bool "Activate AMD Secure Memory Encryption (SME) by default"
1551 depends on AMD_MEM_ENCRYPT
1553 Say yes to have system memory encrypted by default if running on
1554 an AMD processor that supports Secure Memory Encryption (SME).
1556 If set to Y, then the encryption of system memory can be
1557 deactivated with the mem_encrypt=off command line option.
1559 If set to N, then the encryption of system memory can be
1560 activated with the mem_encrypt=on command line option.
1562 # Common NUMA Features
1564 bool "NUMA Memory Allocation and Scheduler Support"
1566 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1567 default y if X86_BIGSMP
1568 select USE_PERCPU_NUMA_NODE_ID
1570 Enable NUMA (Non-Uniform Memory Access) support.
1572 The kernel will try to allocate memory used by a CPU on the
1573 local memory controller of the CPU and add some more
1574 NUMA awareness to the kernel.
1576 For 64-bit this is recommended if the system is Intel Core i7
1577 (or later), AMD Opteron, or EM64T NUMA.
1579 For 32-bit this is only needed if you boot a 32-bit
1580 kernel on a 64-bit NUMA platform.
1582 Otherwise, you should say N.
1586 prompt "Old style AMD Opteron NUMA detection"
1587 depends on X86_64 && NUMA && PCI
1589 Enable AMD NUMA node topology detection. You should say Y here if
1590 you have a multi processor AMD system. This uses an old method to
1591 read the NUMA configuration directly from the builtin Northbridge
1592 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1593 which also takes priority if both are compiled in.
1595 config X86_64_ACPI_NUMA
1597 prompt "ACPI NUMA detection"
1598 depends on X86_64 && NUMA && ACPI && PCI
1601 Enable ACPI SRAT based node topology detection.
1604 bool "NUMA emulation"
1607 Enable NUMA emulation. A flat machine will be split
1608 into virtual nodes when booted with "numa=fake=N", where N is the
1609 number of nodes. This is only useful for debugging.
1612 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1614 default "10" if MAXSMP
1615 default "6" if X86_64
1619 Specify the maximum number of NUMA Nodes available on the target
1620 system. Increases memory reserved to accommodate various tables.
1622 config ARCH_FLATMEM_ENABLE
1624 depends on X86_32 && !NUMA
1626 config ARCH_SPARSEMEM_ENABLE
1628 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1629 select SPARSEMEM_STATIC if X86_32
1630 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1632 config ARCH_SPARSEMEM_DEFAULT
1633 def_bool X86_64 || (NUMA && X86_32)
1635 config ARCH_SELECT_MEMORY_MODEL
1637 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1639 config ARCH_MEMORY_PROBE
1640 bool "Enable sysfs memory/probe interface"
1641 depends on MEMORY_HOTPLUG
1643 This option enables a sysfs memory/probe interface for testing.
1644 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1645 If you are unsure how to answer this question, answer N.
1647 config ARCH_PROC_KCORE_TEXT
1649 depends on X86_64 && PROC_KCORE
1651 config ILLEGAL_POINTER_VALUE
1654 default 0xdead000000000000 if X86_64
1656 config X86_PMEM_LEGACY_DEVICE
1659 config X86_PMEM_LEGACY
1660 tristate "Support non-standard NVDIMMs and ADR protected memory"
1661 depends on PHYS_ADDR_T_64BIT
1663 select X86_PMEM_LEGACY_DEVICE
1664 select NUMA_KEEP_MEMINFO if NUMA
1667 Treat memory marked using the non-standard e820 type of 12 as used
1668 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1669 The kernel will offer these regions to the 'pmem' driver so
1670 they can be used for persistent storage.
1675 bool "Allocate 3rd-level pagetables from highmem"
1678 The VM uses one page table entry for each page of physical memory.
1679 For systems with a lot of RAM, this can be wasteful of precious
1680 low memory. Setting this option will put user-space page table
1681 entries in high memory.
1683 config X86_CHECK_BIOS_CORRUPTION
1684 bool "Check for low memory corruption"
1686 Periodically check for memory corruption in low memory, which
1687 is suspected to be caused by BIOS. Even when enabled in the
1688 configuration, it is disabled at runtime. Enable it by
1689 setting "memory_corruption_check=1" on the kernel command
1690 line. By default it scans the low 64k of memory every 60
1691 seconds; see the memory_corruption_check_size and
1692 memory_corruption_check_period parameters in
1693 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1695 When enabled with the default parameters, this option has
1696 almost no overhead, as it reserves a relatively small amount
1697 of memory and scans it infrequently. It both detects corruption
1698 and prevents it from affecting the running system.
1700 It is, however, intended as a diagnostic tool; if repeatable
1701 BIOS-originated corruption always affects the same memory,
1702 you can use memmap= to prevent the kernel from using that
1705 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1706 bool "Set the default setting of memory_corruption_check"
1707 depends on X86_CHECK_BIOS_CORRUPTION
1710 Set whether the default state of memory_corruption_check is
1713 config MATH_EMULATION
1715 depends on MODIFY_LDT_SYSCALL
1716 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1718 Linux can emulate a math coprocessor (used for floating point
1719 operations) if you don't have one. 486DX and Pentium processors have
1720 a math coprocessor built in, 486SX and 386 do not, unless you added
1721 a 487DX or 387, respectively. (The messages during boot time can
1722 give you some hints here ["man dmesg"].) Everyone needs either a
1723 coprocessor or this emulation.
1725 If you don't have a math coprocessor, you need to say Y here; if you
1726 say Y here even though you have a coprocessor, the coprocessor will
1727 be used nevertheless. (This behavior can be changed with the kernel
1728 command line option "no387", which comes handy if your coprocessor
1729 is broken. Try "man bootparam" or see the documentation of your boot
1730 loader (lilo or loadlin) about how to pass options to the kernel at
1731 boot time.) This means that it is a good idea to say Y here if you
1732 intend to use this kernel on different machines.
1734 More information about the internals of the Linux math coprocessor
1735 emulation can be found in <file:arch/x86/math-emu/README>.
1737 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1738 kernel, it won't hurt.
1742 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1744 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1745 the Memory Type Range Registers (MTRRs) may be used to control
1746 processor access to memory ranges. This is most useful if you have
1747 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1748 allows bus write transfers to be combined into a larger transfer
1749 before bursting over the PCI/AGP bus. This can increase performance
1750 of image write operations 2.5 times or more. Saying Y here creates a
1751 /proc/mtrr file which may be used to manipulate your processor's
1752 MTRRs. Typically the X server should use this.
1754 This code has a reasonably generic interface so that similar
1755 control registers on other processors can be easily supported
1758 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1759 Registers (ARRs) which provide a similar functionality to MTRRs. For
1760 these, the ARRs are used to emulate the MTRRs.
1761 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1762 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1763 write-combining. All of these processors are supported by this code
1764 and it makes sense to say Y here if you have one of them.
1766 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1767 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1768 can lead to all sorts of problems, so it's good to say Y here.
1770 You can safely say Y even if your machine doesn't have MTRRs, you'll
1771 just add about 9 KB to your kernel.
1773 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1775 config MTRR_SANITIZER
1777 prompt "MTRR cleanup support"
1780 Convert MTRR layout from continuous to discrete, so X drivers can
1781 add writeback entries.
1783 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1784 The largest mtrr entry size for a continuous block can be set with
1789 config MTRR_SANITIZER_ENABLE_DEFAULT
1790 int "MTRR cleanup enable value (0-1)"
1793 depends on MTRR_SANITIZER
1795 Enable mtrr cleanup default value
1797 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1798 int "MTRR cleanup spare reg num (0-7)"
1801 depends on MTRR_SANITIZER
1803 mtrr cleanup spare entries default, it can be changed via
1804 mtrr_spare_reg_nr=N on the kernel command line.
1808 prompt "x86 PAT support" if EXPERT
1811 Use PAT attributes to setup page level cache control.
1813 PATs are the modern equivalents of MTRRs and are much more
1814 flexible than MTRRs.
1816 Say N here if you see bootup problems (boot crash, boot hang,
1817 spontaneous reboots) or a non-working video driver.
1821 config ARCH_USES_PG_UNCACHED
1827 prompt "User Mode Instruction Prevention" if EXPERT
1829 User Mode Instruction Prevention (UMIP) is a security feature in
1830 some x86 processors. If enabled, a general protection fault is
1831 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1832 executed in user mode. These instructions unnecessarily expose
1833 information about the hardware state.
1835 The vast majority of applications do not use these instructions.
1836 For the very few that do, software emulation is provided in
1837 specific cases in protected and virtual-8086 modes. Emulated
1841 # GCC >= 9 and binutils >= 2.29
1842 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1844 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1845 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1846 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1847 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1850 config X86_KERNEL_IBT
1851 prompt "Indirect Branch Tracking"
1853 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1854 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1855 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1858 Build the kernel with support for Indirect Branch Tracking, a
1859 hardware support course-grain forward-edge Control Flow Integrity
1860 protection. It enforces that all indirect calls must land on
1861 an ENDBR instruction, as such, the compiler will instrument the
1862 code with them to make this happen.
1864 In addition to building the kernel with IBT, seal all functions that
1865 are not indirect call targets, avoiding them ever becoming one.
1867 This requires LTO like objtool runs and will slow down the build. It
1868 does significantly reduce the number of ENDBR instructions in the
1871 config X86_INTEL_MEMORY_PROTECTION_KEYS
1872 prompt "Memory Protection Keys"
1874 # Note: only available in 64-bit mode
1875 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1876 select ARCH_USES_HIGH_VMA_FLAGS
1877 select ARCH_HAS_PKEYS
1879 Memory Protection Keys provides a mechanism for enforcing
1880 page-based protections, but without requiring modification of the
1881 page tables when an application changes protection domains.
1883 For details, see Documentation/core-api/protection-keys.rst
1888 prompt "TSX enable mode"
1889 depends on CPU_SUP_INTEL
1890 default X86_INTEL_TSX_MODE_OFF
1892 Intel's TSX (Transactional Synchronization Extensions) feature
1893 allows to optimize locking protocols through lock elision which
1894 can lead to a noticeable performance boost.
1896 On the other hand it has been shown that TSX can be exploited
1897 to form side channel attacks (e.g. TAA) and chances are there
1898 will be more of those attacks discovered in the future.
1900 Therefore TSX is not enabled by default (aka tsx=off). An admin
1901 might override this decision by tsx=on the command line parameter.
1902 Even with TSX enabled, the kernel will attempt to enable the best
1903 possible TAA mitigation setting depending on the microcode available
1904 for the particular machine.
1906 This option allows to set the default tsx mode between tsx=on, =off
1907 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1910 Say off if not sure, auto if TSX is in use but it should be used on safe
1911 platforms or on if TSX is in use and the security aspect of tsx is not
1914 config X86_INTEL_TSX_MODE_OFF
1917 TSX is disabled if possible - equals to tsx=off command line parameter.
1919 config X86_INTEL_TSX_MODE_ON
1922 TSX is always enabled on TSX capable HW - equals the tsx=on command
1925 config X86_INTEL_TSX_MODE_AUTO
1928 TSX is enabled on TSX capable HW that is believed to be safe against
1929 side channel attacks- equals the tsx=auto command line parameter.
1933 bool "Software Guard eXtensions (SGX)"
1934 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1936 depends on CRYPTO_SHA256=y
1938 select NUMA_KEEP_MEMINFO if NUMA
1941 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1942 that can be used by applications to set aside private regions of code
1943 and data, referred to as enclaves. An enclave's private memory can
1944 only be accessed by code running within the enclave. Accesses from
1945 outside the enclave, including other enclaves, are disallowed by
1951 bool "EFI runtime service support"
1954 select EFI_RUNTIME_WRAPPERS
1955 select ARCH_USE_MEMREMAP_PROT
1957 This enables the kernel to use EFI runtime services that are
1958 available (such as the EFI variable services).
1960 This option is only useful on systems that have EFI firmware.
1961 In addition, you should use the latest ELILO loader available
1962 at <http://elilo.sourceforge.net> in order to take advantage
1963 of EFI runtime services. However, even with this option, the
1964 resultant kernel should continue to boot on existing non-EFI
1968 bool "EFI stub support"
1972 This kernel feature allows a bzImage to be loaded directly
1973 by EFI firmware without the use of a bootloader.
1975 See Documentation/admin-guide/efi-stub.rst for more information.
1977 config EFI_HANDOVER_PROTOCOL
1978 bool "EFI handover protocol (DEPRECATED)"
1982 Select this in order to include support for the deprecated EFI
1983 handover protocol, which defines alternative entry points into the
1984 EFI stub. This is a practice that has no basis in the UEFI
1985 specification, and requires a priori knowledge on the part of the
1986 bootloader about Linux/x86 specific ways of passing the command line
1987 and initrd, and where in memory those assets may be loaded.
1989 If in doubt, say Y. Even though the corresponding support is not
1990 present in upstream GRUB or other bootloaders, most distros build
1991 GRUB with numerous downstream patches applied, and may rely on the
1992 handover protocol as as result.
1995 bool "EFI mixed-mode support"
1996 depends on EFI_STUB && X86_64
1998 Enabling this feature allows a 64-bit kernel to be booted
1999 on a 32-bit firmware, provided that your CPU supports 64-bit
2002 Note that it is not possible to boot a mixed-mode enabled
2003 kernel via the EFI boot stub - a bootloader that supports
2004 the EFI handover protocol must be used.
2008 config EFI_FAKE_MEMMAP
2009 bool "Enable EFI fake memory map"
2012 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2013 this parameter, you can add arbitrary attribute to specific memory
2014 range by updating original (firmware provided) EFI memmap. This is
2015 useful for debugging of EFI memmap related feature, e.g., Address
2016 Range Mirroring feature.
2018 config EFI_MAX_FAKE_MEM
2019 int "maximum allowable number of ranges in efi_fake_mem boot option"
2020 depends on EFI_FAKE_MEMMAP
2024 Maximum allowable number of ranges in efi_fake_mem boot option.
2025 Ranges can be set up to this value using comma-separated list.
2026 The default value is 8.
2028 config EFI_RUNTIME_MAP
2029 bool "Export EFI runtime maps to sysfs" if EXPERT
2033 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2034 That memory map is required by the 2nd kernel to set up EFI virtual
2035 mappings after kexec, but can also be used for debugging purposes.
2037 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2039 source "kernel/Kconfig.hz"
2042 bool "kexec system call"
2045 kexec is a system call that implements the ability to shutdown your
2046 current kernel, and to start another kernel. It is like a reboot
2047 but it is independent of the system firmware. And like a reboot
2048 you can start any kernel with it, not just Linux.
2050 The name comes from the similarity to the exec system call.
2052 It is an ongoing process to be certain the hardware in a machine
2053 is properly shutdown, so do not be surprised if this code does not
2054 initially work for you. As of this writing the exact hardware
2055 interface is strongly in flux, so no good recommendation can be
2059 bool "kexec file based system call"
2061 select HAVE_IMA_KEXEC if IMA
2064 depends on CRYPTO_SHA256=y
2066 This is new version of kexec system call. This system call is
2067 file based and takes file descriptors as system call argument
2068 for kernel and initramfs as opposed to list of segments as
2069 accepted by previous system call.
2071 config ARCH_HAS_KEXEC_PURGATORY
2075 bool "Verify kernel signature during kexec_file_load() syscall"
2076 depends on KEXEC_FILE
2079 This option makes the kexec_file_load() syscall check for a valid
2080 signature of the kernel image. The image can still be loaded without
2081 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2082 there's a signature that we can check, then it must be valid.
2084 In addition to this option, you need to enable signature
2085 verification for the corresponding kernel image type being
2086 loaded in order for this to work.
2088 config KEXEC_SIG_FORCE
2089 bool "Require a valid signature in kexec_file_load() syscall"
2090 depends on KEXEC_SIG
2092 This option makes kernel signature verification mandatory for
2093 the kexec_file_load() syscall.
2095 config KEXEC_BZIMAGE_VERIFY_SIG
2096 bool "Enable bzImage signature verification support"
2097 depends on KEXEC_SIG
2098 depends on SIGNED_PE_FILE_VERIFICATION
2099 select SYSTEM_TRUSTED_KEYRING
2101 Enable bzImage signature verification support.
2104 bool "kernel crash dumps"
2105 depends on X86_64 || (X86_32 && HIGHMEM)
2107 Generate crash dump after being started by kexec.
2108 This should be normally only set in special crash dump kernels
2109 which are loaded in the main kernel with kexec-tools into
2110 a specially reserved region and then later executed after
2111 a crash by kdump/kexec. The crash dump kernel must be compiled
2112 to a memory address not used by the main kernel or BIOS using
2113 PHYSICAL_START, or it must be built as a relocatable image
2114 (CONFIG_RELOCATABLE=y).
2115 For more details see Documentation/admin-guide/kdump/kdump.rst
2119 depends on KEXEC && HIBERNATION
2121 Jump between original kernel and kexeced kernel and invoke
2122 code in physical address mode via KEXEC
2124 config PHYSICAL_START
2125 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2128 This gives the physical address where the kernel is loaded.
2130 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2131 bzImage will decompress itself to above physical address and
2132 run from there. Otherwise, bzImage will run from the address where
2133 it has been loaded by the boot loader and will ignore above physical
2136 In normal kdump cases one does not have to set/change this option
2137 as now bzImage can be compiled as a completely relocatable image
2138 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2139 address. This option is mainly useful for the folks who don't want
2140 to use a bzImage for capturing the crash dump and want to use a
2141 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2142 to be specifically compiled to run from a specific memory area
2143 (normally a reserved region) and this option comes handy.
2145 So if you are using bzImage for capturing the crash dump,
2146 leave the value here unchanged to 0x1000000 and set
2147 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2148 for capturing the crash dump change this value to start of
2149 the reserved region. In other words, it can be set based on
2150 the "X" value as specified in the "crashkernel=YM@XM"
2151 command line boot parameter passed to the panic-ed
2152 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2153 for more details about crash dumps.
2155 Usage of bzImage for capturing the crash dump is recommended as
2156 one does not have to build two kernels. Same kernel can be used
2157 as production kernel and capture kernel. Above option should have
2158 gone away after relocatable bzImage support is introduced. But it
2159 is present because there are users out there who continue to use
2160 vmlinux for dump capture. This option should go away down the
2163 Don't change this unless you know what you are doing.
2166 bool "Build a relocatable kernel"
2169 This builds a kernel image that retains relocation information
2170 so it can be loaded someplace besides the default 1MB.
2171 The relocations tend to make the kernel binary about 10% larger,
2172 but are discarded at runtime.
2174 One use is for the kexec on panic case where the recovery kernel
2175 must live at a different physical address than the primary
2178 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2179 it has been loaded at and the compile time physical address
2180 (CONFIG_PHYSICAL_START) is used as the minimum location.
2182 config RANDOMIZE_BASE
2183 bool "Randomize the address of the kernel image (KASLR)"
2184 depends on RELOCATABLE
2187 In support of Kernel Address Space Layout Randomization (KASLR),
2188 this randomizes the physical address at which the kernel image
2189 is decompressed and the virtual address where the kernel
2190 image is mapped, as a security feature that deters exploit
2191 attempts relying on knowledge of the location of kernel
2194 On 64-bit, the kernel physical and virtual addresses are
2195 randomized separately. The physical address will be anywhere
2196 between 16MB and the top of physical memory (up to 64TB). The
2197 virtual address will be randomized from 16MB up to 1GB (9 bits
2198 of entropy). Note that this also reduces the memory space
2199 available to kernel modules from 1.5GB to 1GB.
2201 On 32-bit, the kernel physical and virtual addresses are
2202 randomized together. They will be randomized from 16MB up to
2203 512MB (8 bits of entropy).
2205 Entropy is generated using the RDRAND instruction if it is
2206 supported. If RDTSC is supported, its value is mixed into
2207 the entropy pool as well. If neither RDRAND nor RDTSC are
2208 supported, then entropy is read from the i8254 timer. The
2209 usable entropy is limited by the kernel being built using
2210 2GB addressing, and that PHYSICAL_ALIGN must be at a
2211 minimum of 2MB. As a result, only 10 bits of entropy are
2212 theoretically possible, but the implementations are further
2213 limited due to memory layouts.
2217 # Relocation on x86 needs some additional build support
2218 config X86_NEED_RELOCS
2220 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2222 config PHYSICAL_ALIGN
2223 hex "Alignment value to which kernel should be aligned"
2225 range 0x2000 0x1000000 if X86_32
2226 range 0x200000 0x1000000 if X86_64
2228 This value puts the alignment restrictions on physical address
2229 where kernel is loaded and run from. Kernel is compiled for an
2230 address which meets above alignment restriction.
2232 If bootloader loads the kernel at a non-aligned address and
2233 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2234 address aligned to above value and run from there.
2236 If bootloader loads the kernel at a non-aligned address and
2237 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2238 load address and decompress itself to the address it has been
2239 compiled for and run from there. The address for which kernel is
2240 compiled already meets above alignment restrictions. Hence the
2241 end result is that kernel runs from a physical address meeting
2242 above alignment restrictions.
2244 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2245 this value must be a multiple of 0x200000.
2247 Don't change this unless you know what you are doing.
2249 config DYNAMIC_MEMORY_LAYOUT
2252 This option makes base addresses of vmalloc and vmemmap as well as
2253 __PAGE_OFFSET movable during boot.
2255 config RANDOMIZE_MEMORY
2256 bool "Randomize the kernel memory sections"
2258 depends on RANDOMIZE_BASE
2259 select DYNAMIC_MEMORY_LAYOUT
2260 default RANDOMIZE_BASE
2262 Randomizes the base virtual address of kernel memory sections
2263 (physical memory mapping, vmalloc & vmemmap). This security feature
2264 makes exploits relying on predictable memory locations less reliable.
2266 The order of allocations remains unchanged. Entropy is generated in
2267 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2268 configuration have in average 30,000 different possible virtual
2269 addresses for each memory section.
2273 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2274 hex "Physical memory mapping padding" if EXPERT
2275 depends on RANDOMIZE_MEMORY
2276 default "0xa" if MEMORY_HOTPLUG
2278 range 0x1 0x40 if MEMORY_HOTPLUG
2281 Define the padding in terabytes added to the existing physical
2282 memory size during kernel memory randomization. It is useful
2283 for memory hotplug support but reduces the entropy available for
2284 address randomization.
2286 If unsure, leave at the default value.
2288 config ADDRESS_MASKING
2289 bool "Linear Address Masking support"
2292 Linear Address Masking (LAM) modifies the checking that is applied
2293 to 64-bit linear addresses, allowing software to use of the
2294 untranslated address bits for metadata.
2296 The capability can be used for efficient address sanitizers (ASAN)
2297 implementation and for optimizations in JITs.
2305 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2306 depends on COMPAT_32
2308 Certain buggy versions of glibc will crash if they are
2309 presented with a 32-bit vDSO that is not mapped at the address
2310 indicated in its segment table.
2312 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2313 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2314 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2315 the only released version with the bug, but OpenSUSE 9
2316 contains a buggy "glibc 2.3.2".
2318 The symptom of the bug is that everything crashes on startup, saying:
2319 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2321 Saying Y here changes the default value of the vdso32 boot
2322 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2323 This works around the glibc bug but hurts performance.
2325 If unsure, say N: if you are compiling your own kernel, you
2326 are unlikely to be using a buggy version of glibc.
2329 prompt "vsyscall table for legacy applications"
2331 default LEGACY_VSYSCALL_XONLY
2333 Legacy user code that does not know how to find the vDSO expects
2334 to be able to issue three syscalls by calling fixed addresses in
2335 kernel space. Since this location is not randomized with ASLR,
2336 it can be used to assist security vulnerability exploitation.
2338 This setting can be changed at boot time via the kernel command
2339 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2340 is deprecated and can only be enabled using the kernel command
2343 On a system with recent enough glibc (2.14 or newer) and no
2344 static binaries, you can say None without a performance penalty
2345 to improve security.
2347 If unsure, select "Emulate execution only".
2349 config LEGACY_VSYSCALL_XONLY
2350 bool "Emulate execution only"
2352 The kernel traps and emulates calls into the fixed vsyscall
2353 address mapping and does not allow reads. This
2354 configuration is recommended when userspace might use the
2355 legacy vsyscall area but support for legacy binary
2356 instrumentation of legacy code is not needed. It mitigates
2357 certain uses of the vsyscall area as an ASLR-bypassing
2360 config LEGACY_VSYSCALL_NONE
2363 There will be no vsyscall mapping at all. This will
2364 eliminate any risk of ASLR bypass due to the vsyscall
2365 fixed address mapping. Attempts to use the vsyscalls
2366 will be reported to dmesg, so that either old or
2367 malicious userspace programs can be identified.
2372 bool "Built-in kernel command line"
2374 Allow for specifying boot arguments to the kernel at
2375 build time. On some systems (e.g. embedded ones), it is
2376 necessary or convenient to provide some or all of the
2377 kernel boot arguments with the kernel itself (that is,
2378 to not rely on the boot loader to provide them.)
2380 To compile command line arguments into the kernel,
2381 set this option to 'Y', then fill in the
2382 boot arguments in CONFIG_CMDLINE.
2384 Systems with fully functional boot loaders (i.e. non-embedded)
2385 should leave this option set to 'N'.
2388 string "Built-in kernel command string"
2389 depends on CMDLINE_BOOL
2392 Enter arguments here that should be compiled into the kernel
2393 image and used at boot time. If the boot loader provides a
2394 command line at boot time, it is appended to this string to
2395 form the full kernel command line, when the system boots.
2397 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2398 change this behavior.
2400 In most cases, the command line (whether built-in or provided
2401 by the boot loader) should specify the device for the root
2404 config CMDLINE_OVERRIDE
2405 bool "Built-in command line overrides boot loader arguments"
2406 depends on CMDLINE_BOOL && CMDLINE != ""
2408 Set this option to 'Y' to have the kernel ignore the boot loader
2409 command line, and use ONLY the built-in command line.
2411 This is used to work around broken boot loaders. This should
2412 be set to 'N' under normal conditions.
2414 config MODIFY_LDT_SYSCALL
2415 bool "Enable the LDT (local descriptor table)" if EXPERT
2418 Linux can allow user programs to install a per-process x86
2419 Local Descriptor Table (LDT) using the modify_ldt(2) system
2420 call. This is required to run 16-bit or segmented code such as
2421 DOSEMU or some Wine programs. It is also used by some very old
2422 threading libraries.
2424 Enabling this feature adds a small amount of overhead to
2425 context switches and increases the low-level kernel attack
2426 surface. Disabling it removes the modify_ldt(2) system call.
2428 Saying 'N' here may make sense for embedded or server kernels.
2430 config STRICT_SIGALTSTACK_SIZE
2431 bool "Enforce strict size checking for sigaltstack"
2432 depends on DYNAMIC_SIGFRAME
2434 For historical reasons MINSIGSTKSZ is a constant which became
2435 already too small with AVX512 support. Add a mechanism to
2436 enforce strict checking of the sigaltstack size against the
2437 real size of the FPU frame. This option enables the check
2438 by default. It can also be controlled via the kernel command
2439 line option 'strict_sas_size' independent of this config
2440 switch. Enabling it might break existing applications which
2441 allocate a too small sigaltstack but 'work' because they
2442 never get a signal delivered.
2444 Say 'N' unless you want to really enforce this check.
2446 source "kernel/livepatch/Kconfig"
2451 def_bool $(cc-option,-mharden-sls=all)
2453 config CC_HAS_RETURN_THUNK
2454 def_bool $(cc-option,-mfunction-return=thunk-extern)
2456 config CC_HAS_ENTRY_PADDING
2457 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2459 config FUNCTION_PADDING_CFI
2461 default 59 if FUNCTION_ALIGNMENT_64B
2462 default 27 if FUNCTION_ALIGNMENT_32B
2463 default 11 if FUNCTION_ALIGNMENT_16B
2464 default 3 if FUNCTION_ALIGNMENT_8B
2467 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2468 # except Kconfig can't do arithmetic :/
2469 config FUNCTION_PADDING_BYTES
2471 default FUNCTION_PADDING_CFI if CFI_CLANG
2472 default FUNCTION_ALIGNMENT
2476 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2477 select FUNCTION_ALIGNMENT_16B
2481 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2484 config HAVE_CALL_THUNKS
2486 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2492 config PREFIX_SYMBOLS
2494 depends on CALL_PADDING && !CFI_CLANG
2496 menuconfig SPECULATION_MITIGATIONS
2497 bool "Mitigations for speculative execution vulnerabilities"
2500 Say Y here to enable options which enable mitigations for
2501 speculative execution hardware vulnerabilities.
2503 If you say N, all mitigations will be disabled. You really
2504 should know what you are doing to say so.
2506 if SPECULATION_MITIGATIONS
2508 config PAGE_TABLE_ISOLATION
2509 bool "Remove the kernel mapping in user mode"
2511 depends on (X86_64 || X86_PAE)
2513 This feature reduces the number of hardware side channels by
2514 ensuring that the majority of kernel addresses are not mapped
2517 See Documentation/arch/x86/pti.rst for more details.
2520 bool "Avoid speculative indirect branches in kernel"
2521 select OBJTOOL if HAVE_OBJTOOL
2524 Compile kernel with the retpoline compiler options to guard against
2525 kernel-to-user data leaks by avoiding speculative indirect
2526 branches. Requires a compiler with -mindirect-branch=thunk-extern
2527 support for full protection. The kernel may run slower.
2530 bool "Enable return-thunks"
2531 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2532 select OBJTOOL if HAVE_OBJTOOL
2535 Compile the kernel with the return-thunks compiler option to guard
2536 against kernel-to-user data leaks by avoiding return speculation.
2537 Requires a compiler with -mfunction-return=thunk-extern
2538 support for full protection. The kernel may run slower.
2540 config CPU_UNRET_ENTRY
2541 bool "Enable UNRET on kernel entry"
2542 depends on CPU_SUP_AMD && RETHUNK && X86_64
2545 Compile the kernel with support for the retbleed=unret mitigation.
2547 config CALL_DEPTH_TRACKING
2548 bool "Mitigate RSB underflow with call depth tracking"
2549 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2550 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2554 Compile the kernel with call depth tracking to mitigate the Intel
2555 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2556 mitigation is off by default and needs to be enabled on the
2557 kernel command line via the retbleed=stuff option. For
2558 non-affected systems the overhead of this option is marginal as
2559 the call depth tracking is using run-time generated call thunks
2560 in a compiler generated padding area and call patching. This
2561 increases text size by ~5%. For non affected systems this space
2562 is unused. On affected SKL systems this results in a significant
2563 performance gain over the IBRS mitigation.
2565 config CALL_THUNKS_DEBUG
2566 bool "Enable call thunks and call depth tracking debugging"
2567 depends on CALL_DEPTH_TRACKING
2568 select FUNCTION_ALIGNMENT_32B
2571 Enable call/ret counters for imbalance detection and build in
2572 a noisy dmesg about callthunks generation and call patching for
2573 trouble shooting. The debug prints need to be enabled on the
2574 kernel command line with 'debug-callthunks'.
2575 Only enable this when you are debugging call thunks as this
2576 creates a noticeable runtime overhead. If unsure say N.
2578 config CPU_IBPB_ENTRY
2579 bool "Enable IBPB on kernel entry"
2580 depends on CPU_SUP_AMD && X86_64
2583 Compile the kernel with support for the retbleed=ibpb mitigation.
2585 config CPU_IBRS_ENTRY
2586 bool "Enable IBRS on kernel entry"
2587 depends on CPU_SUP_INTEL && X86_64
2590 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2591 This mitigates both spectre_v2 and retbleed at great cost to
2595 bool "Mitigate Straight-Line-Speculation"
2596 depends on CC_HAS_SLS && X86_64
2597 select OBJTOOL if HAVE_OBJTOOL
2600 Compile the kernel with straight-line-speculation options to guard
2601 against straight line speculation. The kernel image might be slightly
2606 config ARCH_HAS_ADD_PAGES
2608 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2610 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2613 menu "Power management and ACPI options"
2615 config ARCH_HIBERNATION_HEADER
2617 depends on HIBERNATION
2619 source "kernel/power/Kconfig"
2621 source "drivers/acpi/Kconfig"
2628 tristate "APM (Advanced Power Management) BIOS support"
2629 depends on X86_32 && PM_SLEEP
2631 APM is a BIOS specification for saving power using several different
2632 techniques. This is mostly useful for battery powered laptops with
2633 APM compliant BIOSes. If you say Y here, the system time will be
2634 reset after a RESUME operation, the /proc/apm device will provide
2635 battery status information, and user-space programs will receive
2636 notification of APM "events" (e.g. battery status change).
2638 If you select "Y" here, you can disable actual use of the APM
2639 BIOS by passing the "apm=off" option to the kernel at boot time.
2641 Note that the APM support is almost completely disabled for
2642 machines with more than one CPU.
2644 In order to use APM, you will need supporting software. For location
2645 and more information, read <file:Documentation/power/apm-acpi.rst>
2646 and the Battery Powered Linux mini-HOWTO, available from
2647 <http://www.tldp.org/docs.html#howto>.
2649 This driver does not spin down disk drives (see the hdparm(8)
2650 manpage ("man 8 hdparm") for that), and it doesn't turn off
2651 VESA-compliant "green" monitors.
2653 This driver does not support the TI 4000M TravelMate and the ACER
2654 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2655 desktop machines also don't have compliant BIOSes, and this driver
2656 may cause those machines to panic during the boot phase.
2658 Generally, if you don't have a battery in your machine, there isn't
2659 much point in using this driver and you should say N. If you get
2660 random kernel OOPSes or reboots that don't seem to be related to
2661 anything, try disabling/enabling this option (or disabling/enabling
2664 Some other things you should try when experiencing seemingly random,
2667 1) make sure that you have enough swap space and that it is
2669 2) pass the "idle=poll" option to the kernel
2670 3) switch on floating point emulation in the kernel and pass
2671 the "no387" option to the kernel
2672 4) pass the "floppy=nodma" option to the kernel
2673 5) pass the "mem=4M" option to the kernel (thereby disabling
2674 all but the first 4 MB of RAM)
2675 6) make sure that the CPU is not over clocked.
2676 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2677 8) disable the cache from your BIOS settings
2678 9) install a fan for the video card or exchange video RAM
2679 10) install a better fan for the CPU
2680 11) exchange RAM chips
2681 12) exchange the motherboard.
2683 To compile this driver as a module, choose M here: the
2684 module will be called apm.
2688 config APM_IGNORE_USER_SUSPEND
2689 bool "Ignore USER SUSPEND"
2691 This option will ignore USER SUSPEND requests. On machines with a
2692 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2693 series notebooks, it is necessary to say Y because of a BIOS bug.
2695 config APM_DO_ENABLE
2696 bool "Enable PM at boot time"
2698 Enable APM features at boot time. From page 36 of the APM BIOS
2699 specification: "When disabled, the APM BIOS does not automatically
2700 power manage devices, enter the Standby State, enter the Suspend
2701 State, or take power saving steps in response to CPU Idle calls."
2702 This driver will make CPU Idle calls when Linux is idle (unless this
2703 feature is turned off -- see "Do CPU IDLE calls", below). This
2704 should always save battery power, but more complicated APM features
2705 will be dependent on your BIOS implementation. You may need to turn
2706 this option off if your computer hangs at boot time when using APM
2707 support, or if it beeps continuously instead of suspending. Turn
2708 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2709 T400CDT. This is off by default since most machines do fine without
2714 bool "Make CPU Idle calls when idle"
2716 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2717 On some machines, this can activate improved power savings, such as
2718 a slowed CPU clock rate, when the machine is idle. These idle calls
2719 are made after the idle loop has run for some length of time (e.g.,
2720 333 mS). On some machines, this will cause a hang at boot time or
2721 whenever the CPU becomes idle. (On machines with more than one CPU,
2722 this option does nothing.)
2724 config APM_DISPLAY_BLANK
2725 bool "Enable console blanking using APM"
2727 Enable console blanking using the APM. Some laptops can use this to
2728 turn off the LCD backlight when the screen blanker of the Linux
2729 virtual console blanks the screen. Note that this is only used by
2730 the virtual console screen blanker, and won't turn off the backlight
2731 when using the X Window system. This also doesn't have anything to
2732 do with your VESA-compliant power-saving monitor. Further, this
2733 option doesn't work for all laptops -- it might not turn off your
2734 backlight at all, or it might print a lot of errors to the console,
2735 especially if you are using gpm.
2737 config APM_ALLOW_INTS
2738 bool "Allow interrupts during APM BIOS calls"
2740 Normally we disable external interrupts while we are making calls to
2741 the APM BIOS as a measure to lessen the effects of a badly behaving
2742 BIOS implementation. The BIOS should reenable interrupts if it
2743 needs to. Unfortunately, some BIOSes do not -- especially those in
2744 many of the newer IBM Thinkpads. If you experience hangs when you
2745 suspend, try setting this to Y. Otherwise, say N.
2749 source "drivers/cpufreq/Kconfig"
2751 source "drivers/cpuidle/Kconfig"
2753 source "drivers/idle/Kconfig"
2757 menu "Bus options (PCI etc.)"
2760 prompt "PCI access mode"
2761 depends on X86_32 && PCI
2764 On PCI systems, the BIOS can be used to detect the PCI devices and
2765 determine their configuration. However, some old PCI motherboards
2766 have BIOS bugs and may crash if this is done. Also, some embedded
2767 PCI-based systems don't have any BIOS at all. Linux can also try to
2768 detect the PCI hardware directly without using the BIOS.
2770 With this option, you can specify how Linux should detect the
2771 PCI devices. If you choose "BIOS", the BIOS will be used,
2772 if you choose "Direct", the BIOS won't be used, and if you
2773 choose "MMConfig", then PCI Express MMCONFIG will be used.
2774 If you choose "Any", the kernel will try MMCONFIG, then the
2775 direct access method and falls back to the BIOS if that doesn't
2776 work. If unsure, go with the default, which is "Any".
2781 config PCI_GOMMCONFIG
2798 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2800 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2803 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2806 bool "Support mmconfig PCI config space access" if X86_64
2808 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2809 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2813 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2817 depends on PCI && XEN
2819 config MMCONF_FAM10H
2821 depends on X86_64 && PCI_MMCONFIG && ACPI
2823 config PCI_CNB20LE_QUIRK
2824 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2827 Read the PCI windows out of the CNB20LE host bridge. This allows
2828 PCI hotplug to work on systems with the CNB20LE chipset which do
2831 There's no public spec for this chipset, and this functionality
2832 is known to be incomplete.
2834 You should say N unless you know you need this.
2837 bool "ISA bus support on modern systems" if EXPERT
2839 Expose ISA bus device drivers and options available for selection and
2840 configuration. Enable this option if your target machine has an ISA
2841 bus. ISA is an older system, displaced by PCI and newer bus
2842 architectures -- if your target machine is modern, it probably does
2843 not have an ISA bus.
2847 # x86_64 have no ISA slots, but can have ISA-style DMA.
2849 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2852 Enables ISA-style DMA support for devices requiring such controllers.
2860 Find out whether you have ISA slots on your motherboard. ISA is the
2861 name of a bus system, i.e. the way the CPU talks to the other stuff
2862 inside your box. Other bus systems are PCI, EISA, MicroChannel
2863 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2864 newer boards don't support it. If you have ISA, say Y, otherwise N.
2867 tristate "NatSemi SCx200 support"
2869 This provides basic support for National Semiconductor's
2870 (now AMD's) Geode processors. The driver probes for the
2871 PCI-IDs of several on-chip devices, so its a good dependency
2872 for other scx200_* drivers.
2874 If compiled as a module, the driver is named scx200.
2876 config SCx200HR_TIMER
2877 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2881 This driver provides a clocksource built upon the on-chip
2882 27MHz high-resolution timer. Its also a workaround for
2883 NSC Geode SC-1100's buggy TSC, which loses time when the
2884 processor goes idle (as is done by the scheduler). The
2885 other workaround is idle=poll boot option.
2888 bool "One Laptop Per Child support"
2896 Add support for detecting the unique features of the OLPC
2900 bool "OLPC XO-1 Power Management"
2901 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2903 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2906 bool "OLPC XO-1 Real Time Clock"
2907 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2909 Add support for the XO-1 real time clock, which can be used as a
2910 programmable wakeup source.
2913 bool "OLPC XO-1 SCI extras"
2914 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2918 Add support for SCI-based features of the OLPC XO-1 laptop:
2919 - EC-driven system wakeups
2923 - AC adapter status updates
2924 - Battery status updates
2926 config OLPC_XO15_SCI
2927 bool "OLPC XO-1.5 SCI extras"
2928 depends on OLPC && ACPI
2931 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2932 - EC-driven system wakeups
2933 - AC adapter status updates
2934 - Battery status updates
2937 bool "PCEngines ALIX System Support (LED setup)"
2940 This option enables system support for the PCEngines ALIX.
2941 At present this just sets up LEDs for GPIO control on
2942 ALIX2/3/6 boards. However, other system specific setup should
2945 Note: You must still enable the drivers for GPIO and LED support
2946 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2948 Note: You have to set alix.force=1 for boards with Award BIOS.
2951 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2954 This option enables system support for the Soekris Engineering net5501.
2957 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2961 This option enables system support for the Traverse Technologies GEOS.
2964 bool "Technologic Systems TS-5500 platform support"
2966 select CHECK_SIGNATURE
2970 This option enables system support for the Technologic Systems TS-5500.
2976 depends on CPU_SUP_AMD && PCI
2980 menu "Binary Emulations"
2982 config IA32_EMULATION
2983 bool "IA32 Emulation"
2985 select ARCH_WANT_OLD_COMPAT_IPC
2987 select COMPAT_OLD_SIGACTION
2989 Include code to run legacy 32-bit programs under a
2990 64-bit kernel. You should likely turn this on, unless you're
2991 100% sure that you don't have any 32-bit programs left.
2994 bool "x32 ABI for 64-bit mode"
2996 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2997 # compressed debug sections to x86_x32 properly:
2998 # https://github.com/ClangBuiltLinux/linux/issues/514
2999 # https://github.com/ClangBuiltLinux/linux/issues/1141
3000 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3002 Include code to run binaries for the x32 native 32-bit ABI
3003 for 64-bit processors. An x32 process gets access to the
3004 full 64-bit register file and wide data path while leaving
3005 pointers at 32 bits for smaller memory footprint.
3009 depends on IA32_EMULATION || X86_32
3011 select OLD_SIGSUSPEND3
3015 depends on IA32_EMULATION || X86_X32_ABI
3017 config COMPAT_FOR_U64_ALIGNMENT
3023 config HAVE_ATOMIC_IOMAP
3027 source "arch/x86/kvm/Kconfig"
3029 source "arch/x86/Kconfig.assembler"