1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
71 select ARCH_HAS_CACHE_LINE_SIZE
72 select ARCH_HAS_CURRENT_STACK_POINTER
73 select ARCH_HAS_DEBUG_VIRTUAL
74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
75 select ARCH_HAS_DEVMEM_IS_ALLOWED
76 select ARCH_HAS_EARLY_DEBUG if KGDB
77 select ARCH_HAS_ELF_RANDOMIZE
78 select ARCH_HAS_FAST_MULTIPLIER
79 select ARCH_HAS_FORTIFY_SOURCE
80 select ARCH_HAS_GCOV_PROFILE_ALL
81 select ARCH_HAS_KCOV if X86_64
82 select ARCH_HAS_MEM_ENCRYPT
83 select ARCH_HAS_MEMBARRIER_SYNC_CORE
84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85 select ARCH_HAS_PMEM_API if X86_64
86 select ARCH_HAS_PTE_DEVMAP if X86_64
87 select ARCH_HAS_PTE_SPECIAL
88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
89 select ARCH_HAS_COPY_MC if X86_64
90 select ARCH_HAS_SET_MEMORY
91 select ARCH_HAS_SET_DIRECT_MAP
92 select ARCH_HAS_STRICT_KERNEL_RWX
93 select ARCH_HAS_STRICT_MODULE_RWX
94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95 select ARCH_HAS_SYSCALL_WRAPPER
96 select ARCH_HAS_UBSAN_SANITIZE_ALL
97 select ARCH_HAS_VM_GET_PAGE_PROT
98 select ARCH_HAS_DEBUG_WX
99 select ARCH_HAS_ZONE_DMA_SET if EXPERT
100 select ARCH_HAVE_NMI_SAFE_CMPXCHG
101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
102 select ARCH_MIGHT_HAVE_PC_PARPORT
103 select ARCH_MIGHT_HAVE_PC_SERIO
104 select ARCH_STACKWALK
105 select ARCH_SUPPORTS_ACPI
106 select ARCH_SUPPORTS_ATOMIC_RMW
107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
111 select ARCH_SUPPORTS_LTO_CLANG
112 select ARCH_SUPPORTS_LTO_CLANG_THIN
113 select ARCH_USE_BUILTIN_BSWAP
114 select ARCH_USE_MEMTEST
115 select ARCH_USE_QUEUED_RWLOCKS
116 select ARCH_USE_QUEUED_SPINLOCKS
117 select ARCH_USE_SYM_ANNOTATIONS
118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
121 select ARCH_WANTS_NO_INSTR
122 select ARCH_WANT_GENERAL_HUGETLB
123 select ARCH_WANT_HUGE_PMD_SHARE
124 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
125 select ARCH_WANT_LD_ORPHAN_WARN
126 select ARCH_WANTS_THP_SWAP if X86_64
127 select ARCH_HAS_PARANOID_L1D_FLUSH
128 select BUILDTIME_TABLE_SORT
130 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
131 select CLOCKSOURCE_WATCHDOG
132 select DCACHE_WORD_ACCESS
133 select DYNAMIC_SIGFRAME
134 select EDAC_ATOMIC_SCRUB
136 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
137 select GENERIC_CLOCKEVENTS_MIN_ADJUST
138 select GENERIC_CMOS_UPDATE
139 select GENERIC_CPU_AUTOPROBE
140 select GENERIC_CPU_VULNERABILITIES
141 select GENERIC_EARLY_IOREMAP
144 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
145 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
146 select GENERIC_IRQ_MIGRATION if SMP
147 select GENERIC_IRQ_PROBE
148 select GENERIC_IRQ_RESERVATION_MODE
149 select GENERIC_IRQ_SHOW
150 select GENERIC_PENDING_IRQ if SMP
151 select GENERIC_PTDUMP
152 select GENERIC_SMP_IDLE_THREAD
153 select GENERIC_TIME_VSYSCALL
154 select GENERIC_GETTIMEOFDAY
155 select GENERIC_VDSO_TIME_NS
156 select GUP_GET_PTE_LOW_HIGH if X86_PAE
157 select HARDIRQS_SW_RESEND
158 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
159 select HAVE_ACPI_APEI if ACPI
160 select HAVE_ACPI_APEI_NMI if ACPI
161 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
162 select HAVE_ARCH_AUDITSYSCALL
163 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
164 select HAVE_ARCH_HUGE_VMALLOC if X86_64
165 select HAVE_ARCH_JUMP_LABEL
166 select HAVE_ARCH_JUMP_LABEL_RELATIVE
167 select HAVE_ARCH_KASAN if X86_64
168 select HAVE_ARCH_KASAN_VMALLOC if X86_64
169 select HAVE_ARCH_KFENCE
170 select HAVE_ARCH_KGDB
171 select HAVE_ARCH_MMAP_RND_BITS if MMU
172 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
173 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
174 select HAVE_ARCH_PREL32_RELOCATIONS
175 select HAVE_ARCH_SECCOMP_FILTER
176 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
177 select HAVE_ARCH_STACKLEAK
178 select HAVE_ARCH_TRACEHOOK
179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
181 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
182 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
183 select HAVE_ARCH_VMAP_STACK if X86_64
184 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
185 select HAVE_ARCH_WITHIN_STACK_FRAMES
186 select HAVE_ASM_MODVERSIONS
187 select HAVE_CMPXCHG_DOUBLE
188 select HAVE_CMPXCHG_LOCAL
189 select HAVE_CONTEXT_TRACKING if X86_64
190 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
191 select HAVE_C_RECORDMCOUNT
192 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
193 select HAVE_BUILDTIME_MCOUNT_SORT
194 select HAVE_DEBUG_KMEMLEAK
195 select HAVE_DMA_CONTIGUOUS
196 select HAVE_DYNAMIC_FTRACE
197 select HAVE_DYNAMIC_FTRACE_WITH_REGS
198 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
199 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
200 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
201 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
203 select HAVE_EFFICIENT_UNALIGNED_ACCESS
205 select HAVE_EXIT_THREAD
207 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
208 select HAVE_FTRACE_MCOUNT_RECORD
209 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
210 select HAVE_FUNCTION_TRACER
211 select HAVE_GCC_PLUGINS
212 select HAVE_HW_BREAKPOINT
213 select HAVE_IOREMAP_PROT
214 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
215 select HAVE_IRQ_TIME_ACCOUNTING
216 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
217 select HAVE_KERNEL_BZIP2
218 select HAVE_KERNEL_GZIP
219 select HAVE_KERNEL_LZ4
220 select HAVE_KERNEL_LZMA
221 select HAVE_KERNEL_LZO
222 select HAVE_KERNEL_XZ
223 select HAVE_KERNEL_ZSTD
225 select HAVE_KPROBES_ON_FTRACE
226 select HAVE_FUNCTION_ERROR_INJECTION
227 select HAVE_KRETPROBES
230 select HAVE_LIVEPATCH if X86_64
231 select HAVE_MIXED_BREAKPOINTS_REGS
232 select HAVE_MOD_ARCH_SPECIFIC
235 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
237 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
238 select HAVE_OBJTOOL if X86_64
239 select HAVE_OPTPROBES
240 select HAVE_PCSPKR_PLATFORM
241 select HAVE_PERF_EVENTS
242 select HAVE_PERF_EVENTS_NMI
243 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
245 select HAVE_PERF_REGS
246 select HAVE_PERF_USER_STACK_DUMP
247 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
248 select MMU_GATHER_MERGE_VMAS
249 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
250 select HAVE_REGS_AND_STACK_ACCESS_API
251 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
252 select HAVE_FUNCTION_ARG_ACCESS_API
253 select HAVE_SETUP_PER_CPU_AREA
254 select HAVE_SOFTIRQ_ON_OWN_STACK
255 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
256 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
257 select HAVE_STATIC_CALL
258 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
259 select HAVE_PREEMPT_DYNAMIC_CALL
261 select HAVE_SYSCALL_TRACEPOINTS
262 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
263 select HAVE_UNSTABLE_SCHED_CLOCK
264 select HAVE_USER_RETURN_NOTIFIER
265 select HAVE_GENERIC_VDSO
266 select HOTPLUG_SMT if SMP
267 select IRQ_FORCED_THREADING
268 select NEED_PER_CPU_EMBED_FIRST_CHUNK
269 select NEED_PER_CPU_PAGE_FIRST_CHUNK
270 select NEED_SG_DMA_LENGTH
271 select PCI_DOMAINS if PCI
272 select PCI_LOCKLESS_CONFIG if PCI
275 select RTC_MC146818_LIB
278 select SYSCTL_EXCEPTION_TRACE
279 select THREAD_INFO_IN_TASK
280 select TRACE_IRQFLAGS_SUPPORT
281 select TRACE_IRQFLAGS_NMI_SUPPORT
282 select USER_STACKTRACE_SUPPORT
284 select HAVE_ARCH_KCSAN if X86_64
285 select X86_FEATURE_NAMES if PROC_FS
286 select PROC_PID_ARCH_STATUS if PROC_FS
287 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
288 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
290 config INSTRUCTION_DECODER
292 depends on KPROBES || PERF_EVENTS || UPROBES
296 default "elf32-i386" if X86_32
297 default "elf64-x86-64" if X86_64
299 config LOCKDEP_SUPPORT
302 config STACKTRACE_SUPPORT
308 config ARCH_MMAP_RND_BITS_MIN
312 config ARCH_MMAP_RND_BITS_MAX
316 config ARCH_MMAP_RND_COMPAT_BITS_MIN
319 config ARCH_MMAP_RND_COMPAT_BITS_MAX
325 config GENERIC_ISA_DMA
327 depends on ISA_DMA_API
332 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
334 config GENERIC_BUG_RELATIVE_POINTERS
337 config ARCH_MAY_HAVE_PC_FDC
339 depends on ISA_DMA_API
341 config GENERIC_CALIBRATE_DELAY
344 config ARCH_HAS_CPU_RELAX
347 config ARCH_HIBERNATION_POSSIBLE
352 default 1024 if X86_64
355 config ARCH_SUSPEND_POSSIBLE
361 config KASAN_SHADOW_OFFSET
364 default 0xdffffc0000000000
366 config HAVE_INTEL_TXT
368 depends on INTEL_IOMMU && ACPI
372 depends on X86_32 && SMP
376 depends on X86_64 && SMP
378 config ARCH_SUPPORTS_UPROBES
381 config FIX_EARLYCON_MEM
384 config DYNAMIC_PHYSICAL_MASK
387 config PGTABLE_LEVELS
389 default 5 if X86_5LEVEL
394 config CC_HAS_SANE_STACKPROTECTOR
396 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
397 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
399 We have to make sure stack protector is unconditionally disabled if
400 the compiler produces broken code or if it does not let us control
401 the segment on 32-bit kernels.
403 menu "Processor type and features"
406 bool "Symmetric multi-processing support"
408 This enables support for systems with more than one CPU. If you have
409 a system with only one CPU, say N. If you have a system with more
412 If you say N here, the kernel will run on uni- and multiprocessor
413 machines, but will use only one CPU of a multiprocessor machine. If
414 you say Y here, the kernel will run on many, but not all,
415 uniprocessor machines. On a uniprocessor machine, the kernel
416 will run faster if you say N here.
418 Note that if you say Y here and choose architecture "586" or
419 "Pentium" under "Processor family", the kernel will not work on 486
420 architectures. Similarly, multiprocessor kernels for the "PPro"
421 architecture may not work on all Pentium based boards.
423 People using multiprocessor machines who say Y here should also say
424 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
425 Management" code will be disabled if you say Y here.
427 See also <file:Documentation/x86/i386/IO-APIC.rst>,
428 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
429 <http://www.tldp.org/docs.html#howto>.
431 If you don't know what to do here, say N.
433 config X86_FEATURE_NAMES
434 bool "Processor feature human-readable names" if EMBEDDED
437 This option compiles in a table of x86 feature bits and corresponding
438 names. This is required to support /proc/cpuinfo and a few kernel
439 messages. You can disable this to save space, at the expense of
440 making those few kernel messages show numeric feature bits instead.
445 bool "Support x2apic"
446 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
448 This enables x2apic support on CPUs that have this feature.
450 This allows 32-bit apic IDs (so it can support very large systems),
451 and accesses the local apic via MSRs not via mmio.
453 If you don't know what to do here, say N.
456 bool "Enable MPS table" if ACPI
458 depends on X86_LOCAL_APIC
460 For old smp systems that do not have proper acpi support. Newer systems
461 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
465 depends on X86_GOLDFISH
467 config X86_CPU_RESCTRL
468 bool "x86 CPU resource control support"
469 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
471 select PROC_CPU_RESCTRL if PROC_FS
473 Enable x86 CPU resource control support.
475 Provide support for the allocation and monitoring of system resources
478 Intel calls this Intel Resource Director Technology
479 (Intel(R) RDT). More information about RDT can be found in the
480 Intel x86 Architecture Software Developer Manual.
482 AMD calls this AMD Platform Quality of Service (AMD QoS).
483 More information about AMD QoS can be found in the AMD64 Technology
484 Platform Quality of Service Extensions manual.
490 bool "Support for big SMP systems with more than 8 CPUs"
493 This option is needed for the systems that have more than 8 CPUs.
495 config X86_EXTENDED_PLATFORM
496 bool "Support for extended (non-PC) x86 platforms"
499 If you disable this option then the kernel will only support
500 standard PC platforms. (which covers the vast majority of
503 If you enable this option then you'll be able to select support
504 for the following (non-PC) 32 bit x86 platforms:
505 Goldfish (Android emulator)
508 SGI 320/540 (Visual Workstation)
509 STA2X11-based (e.g. Northville)
510 Moorestown MID devices
512 If you have one of these systems, or if you want to build a
513 generic distribution kernel, say Y here - otherwise say N.
517 config X86_EXTENDED_PLATFORM
518 bool "Support for extended (non-PC) x86 platforms"
521 If you disable this option then the kernel will only support
522 standard PC platforms. (which covers the vast majority of
525 If you enable this option then you'll be able to select support
526 for the following (non-PC) 64 bit x86 platforms:
531 If you have one of these systems, or if you want to build a
532 generic distribution kernel, say Y here - otherwise say N.
534 # This is an alphabetically sorted list of 64 bit extended platforms
535 # Please maintain the alphabetic order if and when there are additions
537 bool "Numascale NumaChip"
539 depends on X86_EXTENDED_PLATFORM
542 depends on X86_X2APIC
543 depends on PCI_MMCONFIG
545 Adds support for Numascale NumaChip large-SMP systems. Needed to
546 enable more than ~168 cores.
547 If you don't have one of these, you should say N here.
551 select HYPERVISOR_GUEST
553 depends on X86_64 && PCI
554 depends on X86_EXTENDED_PLATFORM
557 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
558 supposed to run on these EM64T-based machines. Only choose this option
559 if you have one of these machines.
562 bool "SGI Ultraviolet"
564 depends on X86_EXTENDED_PLATFORM
567 depends on KEXEC_CORE
568 depends on X86_X2APIC
571 This option is needed in order to support SGI Ultraviolet systems.
572 If you don't have one of these, you should say N here.
574 # Following is an alphabetically sorted list of 32 bit extended platforms
575 # Please maintain the alphabetic order if and when there are additions
578 bool "Goldfish (Virtual Platform)"
579 depends on X86_EXTENDED_PLATFORM
581 Enable support for the Goldfish virtual platform used primarily
582 for Android development. Unless you are building for the Android
583 Goldfish emulator say N here.
586 bool "CE4100 TV platform"
588 depends on PCI_GODIRECT
589 depends on X86_IO_APIC
591 depends on X86_EXTENDED_PLATFORM
592 select X86_REBOOTFIXUPS
594 select OF_EARLY_FLATTREE
596 Select for the Intel CE media processor (CE4100) SOC.
597 This option compiles in support for the CE4100 SOC for settop
598 boxes and media devices.
601 bool "Intel MID platform support"
602 depends on X86_EXTENDED_PLATFORM
603 depends on X86_PLATFORM_DEVICES
605 depends on X86_64 || (PCI_GOANY && X86_32)
606 depends on X86_IO_APIC
611 Select to build a kernel capable of supporting Intel MID (Mobile
612 Internet Device) platform systems which do not have the PCI legacy
613 interfaces. If you are building for a PC class system say N here.
615 Intel MID platforms are based on an Intel processor and chipset which
616 consume less power than most of the x86 derivatives.
618 config X86_INTEL_QUARK
619 bool "Intel Quark platform support"
621 depends on X86_EXTENDED_PLATFORM
622 depends on X86_PLATFORM_DEVICES
626 depends on X86_IO_APIC
631 Select to include support for Quark X1000 SoC.
632 Say Y here if you have a Quark based system such as the Arduino
633 compatible Intel Galileo.
635 config X86_INTEL_LPSS
636 bool "Intel Low Power Subsystem Support"
637 depends on X86 && ACPI && PCI
642 Select to build support for Intel Low Power Subsystem such as
643 found on Intel Lynxpoint PCH. Selecting this option enables
644 things like clock tree (common clock framework) and pincontrol
645 which are needed by the LPSS peripheral drivers.
647 config X86_AMD_PLATFORM_DEVICE
648 bool "AMD ACPI2Platform devices support"
653 Select to interpret AMD specific ACPI device to platform device
654 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
655 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
656 implemented under PINCTRL subsystem.
659 tristate "Intel SoC IOSF Sideband support for SoC platforms"
662 This option enables sideband register access support for Intel SoC
663 platforms. On these platforms the IOSF sideband is used in lieu of
664 MSR's for some register accesses, mostly but not limited to thermal
665 and power. Drivers may query the availability of this device to
666 determine if they need the sideband in order to work on these
667 platforms. The sideband is available on the following SoC products.
668 This list is not meant to be exclusive.
673 You should say Y if you are running a kernel on one of these SoC's.
675 config IOSF_MBI_DEBUG
676 bool "Enable IOSF sideband access through debugfs"
677 depends on IOSF_MBI && DEBUG_FS
679 Select this option to expose the IOSF sideband access registers (MCR,
680 MDR, MCRX) through debugfs to write and read register information from
681 different units on the SoC. This is most useful for obtaining device
682 state information for debug and analysis. As this is a general access
683 mechanism, users of this option would have specific knowledge of the
684 device they want to access.
686 If you don't require the option or are in doubt, say N.
689 bool "RDC R-321x SoC"
691 depends on X86_EXTENDED_PLATFORM
693 select X86_REBOOTFIXUPS
695 This option is needed for RDC R-321x system-on-chip, also known
697 If you don't have one of these chips, you should say N here.
699 config X86_32_NON_STANDARD
700 bool "Support non-standard 32-bit SMP architectures"
701 depends on X86_32 && SMP
702 depends on X86_EXTENDED_PLATFORM
704 This option compiles in the bigsmp and STA2X11 default
705 subarchitectures. It is intended for a generic binary
706 kernel. If you select them all, kernel will probe it one by
707 one and will fallback to default.
709 # Alphabetically sorted list of Non standard 32 bit platforms
711 config X86_SUPPORTS_MEMORY_FAILURE
713 # MCE code calls memory_failure():
715 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
716 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
717 depends on X86_64 || !SPARSEMEM
718 select ARCH_SUPPORTS_MEMORY_FAILURE
721 bool "STA2X11 Companion Chip Support"
722 depends on X86_32_NON_STANDARD && PCI
727 This adds support for boards based on the STA2X11 IO-Hub,
728 a.k.a. "ConneXt". The chip is used in place of the standard
729 PC chipset, so all "standard" peripherals are missing. If this
730 option is selected the kernel will still be able to boot on
731 standard PC machines.
734 tristate "Eurobraille/Iris poweroff module"
737 The Iris machines from EuroBraille do not have APM or ACPI support
738 to shut themselves down properly. A special I/O sequence is
739 needed to do so, which is what this module does at
742 This is only for Iris machines from EuroBraille.
746 config SCHED_OMIT_FRAME_POINTER
748 prompt "Single-depth WCHAN output"
751 Calculate simpler /proc/<PID>/wchan values. If this option
752 is disabled then wchan values will recurse back to the
753 caller function. This provides more accurate wchan values,
754 at the expense of slightly more scheduling overhead.
756 If in doubt, say "Y".
758 menuconfig HYPERVISOR_GUEST
759 bool "Linux guest support"
761 Say Y here to enable options for running Linux under various hyper-
762 visors. This option enables basic hypervisor detection and platform
765 If you say N, all options in this submenu will be skipped and
766 disabled, and Linux guest support won't be built in.
771 bool "Enable paravirtualization code"
772 depends on HAVE_STATIC_CALL
774 This changes the kernel so it can modify itself when it is run
775 under a hypervisor, potentially improving performance significantly
776 over full virtualization. However, when run without a hypervisor
777 the kernel is theoretically slower and slightly larger.
782 config PARAVIRT_DEBUG
783 bool "paravirt-ops debugging"
784 depends on PARAVIRT && DEBUG_KERNEL
786 Enable to debug paravirt_ops internals. Specifically, BUG if
787 a paravirt_op is missing when it is called.
789 config PARAVIRT_SPINLOCKS
790 bool "Paravirtualization layer for spinlocks"
791 depends on PARAVIRT && SMP
793 Paravirtualized spinlocks allow a pvops backend to replace the
794 spinlock implementation with something virtualization-friendly
795 (for example, block the virtual CPU rather than spinning).
797 It has a minimal impact on native kernels and gives a nice performance
798 benefit on paravirtualized KVM / Xen kernels.
800 If you are unsure how to answer this question, answer Y.
802 config X86_HV_CALLBACK_VECTOR
805 source "arch/x86/xen/Kconfig"
808 bool "KVM Guest support (including kvmclock)"
810 select PARAVIRT_CLOCK
811 select ARCH_CPUIDLE_HALTPOLL
812 select X86_HV_CALLBACK_VECTOR
815 This option enables various optimizations for running under the KVM
816 hypervisor. It includes a paravirtualized clock, so that instead
817 of relying on a PIT (or probably other) emulation by the
818 underlying device model, the host provides the guest with
819 timing infrastructure such as time of day, and system time
821 config ARCH_CPUIDLE_HALTPOLL
823 prompt "Disable host haltpoll when loading haltpoll driver"
825 If virtualized under KVM, disable host haltpoll.
828 bool "Support for running PVH guests"
830 This option enables the PVH entry point for guest virtual machines
831 as specified in the x86/HVM direct boot ABI.
833 config PARAVIRT_TIME_ACCOUNTING
834 bool "Paravirtual steal time accounting"
837 Select this option to enable fine granularity task steal time
838 accounting. Time spent executing other tasks in parallel with
839 the current vCPU is discounted from the vCPU power. To account for
840 that, there can be a small performance impact.
842 If in doubt, say N here.
844 config PARAVIRT_CLOCK
847 config JAILHOUSE_GUEST
848 bool "Jailhouse non-root cell support"
849 depends on X86_64 && PCI
852 This option allows to run Linux as guest in a Jailhouse non-root
853 cell. You can leave this option disabled if you only want to start
854 Jailhouse and run Linux afterwards in the root cell.
857 bool "ACRN Guest support"
859 select X86_HV_CALLBACK_VECTOR
861 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
862 a flexible, lightweight reference open-source hypervisor, built with
863 real-time and safety-criticality in mind. It is built for embedded
864 IOT with small footprint and real-time features. More details can be
865 found in https://projectacrn.org/.
867 config INTEL_TDX_GUEST
868 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
869 depends on X86_64 && CPU_SUP_INTEL
870 depends on X86_X2APIC
871 select ARCH_HAS_CC_PLATFORM
872 select X86_MEM_ENCRYPT
875 Support running as a guest under Intel TDX. Without this support,
876 the guest kernel can not boot or run under TDX.
877 TDX includes memory encryption and integrity capabilities
878 which protect the confidentiality and integrity of guest
879 memory contents and CPU state. TDX guests are protected from
880 some attacks from the VMM.
882 endif # HYPERVISOR_GUEST
884 source "arch/x86/Kconfig.cpu"
888 prompt "HPET Timer Support" if X86_32
890 Use the IA-PC HPET (High Precision Event Timer) to manage
891 time in preference to the PIT and RTC, if a HPET is
893 HPET is the next generation timer replacing legacy 8254s.
894 The HPET provides a stable time base on SMP
895 systems, unlike the TSC, but it is more expensive to access,
896 as it is off-chip. The interface used is documented
897 in the HPET spec, revision 1.
899 You can safely choose Y here. However, HPET will only be
900 activated if the platform and the BIOS support this feature.
901 Otherwise the 8254 will be used for timing services.
903 Choose N to continue using the legacy 8254 timer.
905 config HPET_EMULATE_RTC
907 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
909 # Mark as expert because too many people got it wrong.
910 # The code disables itself when not needed.
913 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
914 bool "Enable DMI scanning" if EXPERT
916 Enabled scanning of DMI to identify machine quirks. Say Y
917 here unless you have verified that your setup is not
918 affected by entries in the DMI blacklist. Required by PNP
922 bool "Old AMD GART IOMMU support"
926 depends on X86_64 && PCI && AMD_NB
928 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
929 GART based hardware IOMMUs.
931 The GART supports full DMA access for devices with 32-bit access
932 limitations, on systems with more than 3 GB. This is usually needed
933 for USB, sound, many IDE/SATA chipsets and some other devices.
935 Newer systems typically have a modern AMD IOMMU, supported via
936 the CONFIG_AMD_IOMMU=y config option.
938 In normal configurations this driver is only active when needed:
939 there's more than 3 GB of memory and the system contains a
940 32-bit limited device.
944 config BOOT_VESA_SUPPORT
947 If true, at least one selected framebuffer driver can take advantage
948 of VESA video modes set at an early boot stage via the vga= parameter.
951 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
952 depends on X86_64 && SMP && DEBUG_KERNEL
953 select CPUMASK_OFFSTACK
955 Enable maximum number of CPUS and NUMA Nodes for this architecture.
959 # The maximum number of CPUs supported:
961 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
962 # and which can be configured interactively in the
963 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
965 # The ranges are different on 32-bit and 64-bit kernels, depending on
966 # hardware capabilities and scalability features of the kernel.
968 # ( If MAXSMP is enabled we just use the highest possible value and disable
969 # interactive configuration. )
972 config NR_CPUS_RANGE_BEGIN
974 default NR_CPUS_RANGE_END if MAXSMP
978 config NR_CPUS_RANGE_END
981 default 64 if SMP && X86_BIGSMP
982 default 8 if SMP && !X86_BIGSMP
985 config NR_CPUS_RANGE_END
988 default 8192 if SMP && CPUMASK_OFFSTACK
989 default 512 if SMP && !CPUMASK_OFFSTACK
992 config NR_CPUS_DEFAULT
995 default 32 if X86_BIGSMP
999 config NR_CPUS_DEFAULT
1002 default 8192 if MAXSMP
1007 int "Maximum number of CPUs" if SMP && !MAXSMP
1008 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1009 default NR_CPUS_DEFAULT
1011 This allows you to specify the maximum number of CPUs which this
1012 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1013 supported value is 8192, otherwise the maximum value is 512. The
1014 minimum value which makes sense is 2.
1016 This is purely to save memory: each supported CPU adds about 8KB
1017 to the kernel image.
1019 config SCHED_CLUSTER
1020 bool "Cluster scheduler support"
1024 Cluster scheduler support improves the CPU scheduler's decision
1025 making when dealing with machines that have clusters of CPUs.
1026 Cluster usually means a couple of CPUs which are placed closely
1027 by sharing mid-level caches, last-level cache tags or internal
1035 prompt "Multi-core scheduler support"
1038 Multi-core scheduler support improves the CPU scheduler's decision
1039 making when dealing with multi-core CPU chips at a cost of slightly
1040 increased overhead in some places. If unsure say N here.
1042 config SCHED_MC_PRIO
1043 bool "CPU core priorities scheduler support"
1044 depends on SCHED_MC && CPU_SUP_INTEL
1045 select X86_INTEL_PSTATE
1049 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1050 core ordering determined at manufacturing time, which allows
1051 certain cores to reach higher turbo frequencies (when running
1052 single threaded workloads) than others.
1054 Enabling this kernel feature teaches the scheduler about
1055 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1056 scheduler's CPU selection logic accordingly, so that higher
1057 overall system performance can be achieved.
1059 This feature will have no effect on CPUs without this feature.
1061 If unsure say Y here.
1065 depends on !SMP && X86_LOCAL_APIC
1068 bool "Local APIC support on uniprocessors" if !PCI_MSI
1070 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1072 A local APIC (Advanced Programmable Interrupt Controller) is an
1073 integrated interrupt controller in the CPU. If you have a single-CPU
1074 system which has a processor with a local APIC, you can say Y here to
1075 enable and use it. If you say Y here even though your machine doesn't
1076 have a local APIC, then the kernel will still run with no slowdown at
1077 all. The local APIC supports CPU-generated self-interrupts (timer,
1078 performance counters), and the NMI watchdog which detects hard
1081 config X86_UP_IOAPIC
1082 bool "IO-APIC support on uniprocessors"
1083 depends on X86_UP_APIC
1085 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1086 SMP-capable replacement for PC-style interrupt controllers. Most
1087 SMP systems and many recent uniprocessor systems have one.
1089 If you have a single-CPU system with an IO-APIC, you can say Y here
1090 to use it. If you say Y here even though your machine doesn't have
1091 an IO-APIC, then the kernel will still run with no slowdown at all.
1093 config X86_LOCAL_APIC
1095 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1096 select IRQ_DOMAIN_HIERARCHY
1097 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1101 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1103 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1104 bool "Reroute for broken boot IRQs"
1105 depends on X86_IO_APIC
1107 This option enables a workaround that fixes a source of
1108 spurious interrupts. This is recommended when threaded
1109 interrupt handling is used on systems where the generation of
1110 superfluous "boot interrupts" cannot be disabled.
1112 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1113 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1114 kernel does during interrupt handling). On chipsets where this
1115 boot IRQ generation cannot be disabled, this workaround keeps
1116 the original IRQ line masked so that only the equivalent "boot
1117 IRQ" is delivered to the CPUs. The workaround also tells the
1118 kernel to set up the IRQ handler on the boot IRQ line. In this
1119 way only one interrupt is delivered to the kernel. Otherwise
1120 the spurious second interrupt may cause the kernel to bring
1121 down (vital) interrupt lines.
1123 Only affects "broken" chipsets. Interrupt sharing may be
1124 increased on these systems.
1127 bool "Machine Check / overheating reporting"
1128 select GENERIC_ALLOCATOR
1131 Machine Check support allows the processor to notify the
1132 kernel if it detects a problem (e.g. overheating, data corruption).
1133 The action the kernel takes depends on the severity of the problem,
1134 ranging from warning messages to halting the machine.
1136 config X86_MCELOG_LEGACY
1137 bool "Support for deprecated /dev/mcelog character device"
1140 Enable support for /dev/mcelog which is needed by the old mcelog
1141 userspace logging daemon. Consider switching to the new generation
1144 config X86_MCE_INTEL
1146 prompt "Intel MCE features"
1147 depends on X86_MCE && X86_LOCAL_APIC
1149 Additional support for intel specific MCE features such as
1150 the thermal monitor.
1154 prompt "AMD MCE features"
1155 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1157 Additional support for AMD specific MCE features such as
1158 the DRAM Error Threshold.
1160 config X86_ANCIENT_MCE
1161 bool "Support for old Pentium 5 / WinChip machine checks"
1162 depends on X86_32 && X86_MCE
1164 Include support for machine check handling on old Pentium 5 or WinChip
1165 systems. These typically need to be enabled explicitly on the command
1168 config X86_MCE_THRESHOLD
1169 depends on X86_MCE_AMD || X86_MCE_INTEL
1172 config X86_MCE_INJECT
1173 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1174 tristate "Machine check injector support"
1176 Provide support for injecting machine checks for testing purposes.
1177 If you don't know what a machine check is and you don't do kernel
1178 QA it is safe to say n.
1180 source "arch/x86/events/Kconfig"
1182 config X86_LEGACY_VM86
1183 bool "Legacy VM86 support"
1186 This option allows user programs to put the CPU into V8086
1187 mode, which is an 80286-era approximation of 16-bit real mode.
1189 Some very old versions of X and/or vbetool require this option
1190 for user mode setting. Similarly, DOSEMU will use it if
1191 available to accelerate real mode DOS programs. However, any
1192 recent version of DOSEMU, X, or vbetool should be fully
1193 functional even without kernel VM86 support, as they will all
1194 fall back to software emulation. Nevertheless, if you are using
1195 a 16-bit DOS program where 16-bit performance matters, vm86
1196 mode might be faster than emulation and you might want to
1199 Note that any app that works on a 64-bit kernel is unlikely to
1200 need this option, as 64-bit kernels don't, and can't, support
1201 V8086 mode. This option is also unrelated to 16-bit protected
1202 mode and is not needed to run most 16-bit programs under Wine.
1204 Enabling this option increases the complexity of the kernel
1205 and slows down exception handling a tiny bit.
1207 If unsure, say N here.
1211 default X86_LEGACY_VM86
1214 bool "Enable support for 16-bit segments" if EXPERT
1216 depends on MODIFY_LDT_SYSCALL
1218 This option is required by programs like Wine to run 16-bit
1219 protected mode legacy code on x86 processors. Disabling
1220 this option saves about 300 bytes on i386, or around 6K text
1221 plus 16K runtime memory on x86-64,
1225 depends on X86_16BIT && X86_32
1229 depends on X86_16BIT && X86_64
1231 config X86_VSYSCALL_EMULATION
1232 bool "Enable vsyscall emulation" if EXPERT
1236 This enables emulation of the legacy vsyscall page. Disabling
1237 it is roughly equivalent to booting with vsyscall=none, except
1238 that it will also disable the helpful warning if a program
1239 tries to use a vsyscall. With this option set to N, offending
1240 programs will just segfault, citing addresses of the form
1243 This option is required by many programs built before 2013, and
1244 care should be used even with newer programs if set to N.
1246 Disabling this option saves about 7K of kernel size and
1247 possibly 4K of additional runtime pagetable memory.
1249 config X86_IOPL_IOPERM
1250 bool "IOPERM and IOPL Emulation"
1253 This enables the ioperm() and iopl() syscalls which are necessary
1254 for legacy applications.
1256 Legacy IOPL support is an overbroad mechanism which allows user
1257 space aside of accessing all 65536 I/O ports also to disable
1258 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1259 capabilities and permission from potentially active security
1262 The emulation restricts the functionality of the syscall to
1263 only allowing the full range I/O port access, but prevents the
1264 ability to disable interrupts from user space which would be
1265 granted if the hardware IOPL mechanism would be used.
1268 tristate "Toshiba Laptop support"
1271 This adds a driver to safely access the System Management Mode of
1272 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1273 not work on models with a Phoenix BIOS. The System Management Mode
1274 is used to set the BIOS and power saving options on Toshiba portables.
1276 For information on utilities to make use of this driver see the
1277 Toshiba Linux utilities web site at:
1278 <http://www.buzzard.org.uk/toshiba/>.
1280 Say Y if you intend to run this kernel on a Toshiba portable.
1283 config X86_REBOOTFIXUPS
1284 bool "Enable X86 board specific fixups for reboot"
1287 This enables chipset and/or board specific fixups to be done
1288 in order to get reboot to work correctly. This is only needed on
1289 some combinations of hardware and BIOS. The symptom, for which
1290 this config is intended, is when reboot ends with a stalled/hung
1293 Currently, the only fixup is for the Geode machines using
1294 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1296 Say Y if you want to enable the fixup. Currently, it's safe to
1297 enable this option even if you don't need it.
1301 bool "CPU microcode loading support"
1303 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1305 If you say Y here, you will be able to update the microcode on
1306 Intel and AMD processors. The Intel support is for the IA32 family,
1307 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1308 AMD support is for families 0x10 and later. You will obviously need
1309 the actual microcode binary data itself which is not shipped with
1312 The preferred method to load microcode from a detached initrd is described
1313 in Documentation/x86/microcode.rst. For that you need to enable
1314 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1315 initrd for microcode blobs.
1317 In addition, you can build the microcode into the kernel. For that you
1318 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1321 config MICROCODE_INTEL
1322 bool "Intel microcode loading support"
1323 depends on CPU_SUP_INTEL && MICROCODE
1326 This options enables microcode patch loading support for Intel
1329 For the current Intel microcode data package go to
1330 <https://downloadcenter.intel.com> and search for
1331 'Linux Processor Microcode Data File'.
1333 config MICROCODE_AMD
1334 bool "AMD microcode loading support"
1335 depends on CPU_SUP_AMD && MICROCODE
1337 If you select this option, microcode patch loading support for AMD
1338 processors will be enabled.
1340 config MICROCODE_LATE_LOADING
1341 bool "Late microcode loading (DANGEROUS)"
1343 depends on MICROCODE
1345 Loading microcode late, when the system is up and executing instructions
1346 is a tricky business and should be avoided if possible. Just the sequence
1347 of synchronizing all cores and SMT threads is one fragile dance which does
1348 not guarantee that cores might not softlock after the loading. Therefore,
1349 use this at your own risk. Late loading taints the kernel too.
1352 tristate "/dev/cpu/*/msr - Model-specific register support"
1354 This device gives privileged processes access to the x86
1355 Model-Specific Registers (MSRs). It is a character device with
1356 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1357 MSR accesses are directed to a specific CPU on multi-processor
1361 tristate "/dev/cpu/*/cpuid - CPU information support"
1363 This device gives processes access to the x86 CPUID instruction to
1364 be executed on a specific processor. It is a character device
1365 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1369 prompt "High Memory Support"
1376 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1377 However, the address space of 32-bit x86 processors is only 4
1378 Gigabytes large. That means that, if you have a large amount of
1379 physical memory, not all of it can be "permanently mapped" by the
1380 kernel. The physical memory that's not permanently mapped is called
1383 If you are compiling a kernel which will never run on a machine with
1384 more than 1 Gigabyte total physical RAM, answer "off" here (default
1385 choice and suitable for most users). This will result in a "3GB/1GB"
1386 split: 3GB are mapped so that each process sees a 3GB virtual memory
1387 space and the remaining part of the 4GB virtual memory space is used
1388 by the kernel to permanently map as much physical memory as
1391 If the machine has between 1 and 4 Gigabytes physical RAM, then
1394 If more than 4 Gigabytes is used then answer "64GB" here. This
1395 selection turns Intel PAE (Physical Address Extension) mode on.
1396 PAE implements 3-level paging on IA32 processors. PAE is fully
1397 supported by Linux, PAE mode is implemented on all recent Intel
1398 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1399 then the kernel will not boot on CPUs that don't support PAE!
1401 The actual amount of total physical memory will either be
1402 auto detected or can be forced by using a kernel command line option
1403 such as "mem=256M". (Try "man bootparam" or see the documentation of
1404 your boot loader (lilo or loadlin) about how to pass options to the
1405 kernel at boot time.)
1407 If unsure, say "off".
1412 Select this if you have a 32-bit processor and between 1 and 4
1413 gigabytes of physical RAM.
1417 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1420 Select this if you have a 32-bit processor and more than 4
1421 gigabytes of physical RAM.
1426 prompt "Memory split" if EXPERT
1430 Select the desired split between kernel and user memory.
1432 If the address range available to the kernel is less than the
1433 physical memory installed, the remaining memory will be available
1434 as "high memory". Accessing high memory is a little more costly
1435 than low memory, as it needs to be mapped into the kernel first.
1436 Note that increasing the kernel address space limits the range
1437 available to user programs, making the address space there
1438 tighter. Selecting anything other than the default 3G/1G split
1439 will also likely make your kernel incompatible with binary-only
1442 If you are not absolutely sure what you are doing, leave this
1446 bool "3G/1G user/kernel split"
1447 config VMSPLIT_3G_OPT
1449 bool "3G/1G user/kernel split (for full 1G low memory)"
1451 bool "2G/2G user/kernel split"
1452 config VMSPLIT_2G_OPT
1454 bool "2G/2G user/kernel split (for full 2G low memory)"
1456 bool "1G/3G user/kernel split"
1461 default 0xB0000000 if VMSPLIT_3G_OPT
1462 default 0x80000000 if VMSPLIT_2G
1463 default 0x78000000 if VMSPLIT_2G_OPT
1464 default 0x40000000 if VMSPLIT_1G
1470 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1473 bool "PAE (Physical Address Extension) Support"
1474 depends on X86_32 && !HIGHMEM4G
1475 select PHYS_ADDR_T_64BIT
1478 PAE is required for NX support, and furthermore enables
1479 larger swapspace support for non-overcommit purposes. It
1480 has the cost of more pagetable lookup overhead, and also
1481 consumes more pagetable space per process.
1484 bool "Enable 5-level page tables support"
1486 select DYNAMIC_MEMORY_LAYOUT
1487 select SPARSEMEM_VMEMMAP
1490 5-level paging enables access to larger address space:
1491 upto 128 PiB of virtual address space and 4 PiB of
1492 physical address space.
1494 It will be supported by future Intel CPUs.
1496 A kernel with the option enabled can be booted on machines that
1497 support 4- or 5-level paging.
1499 See Documentation/x86/x86_64/5level-paging.rst for more
1504 config X86_DIRECT_GBPAGES
1508 Certain kernel features effectively disable kernel
1509 linear 1 GB mappings (even if the CPU otherwise
1510 supports them), so don't confuse the user by printing
1511 that we have them enabled.
1513 config X86_CPA_STATISTICS
1514 bool "Enable statistic for Change Page Attribute"
1517 Expose statistics about the Change Page Attribute mechanism, which
1518 helps to determine the effectiveness of preserving large and huge
1519 page mappings when mapping protections are changed.
1521 config X86_MEM_ENCRYPT
1522 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1523 select DYNAMIC_PHYSICAL_MASK
1526 config AMD_MEM_ENCRYPT
1527 bool "AMD Secure Memory Encryption (SME) support"
1528 depends on X86_64 && CPU_SUP_AMD
1529 select DMA_COHERENT_POOL
1530 select ARCH_USE_MEMREMAP_PROT
1531 select INSTRUCTION_DECODER
1532 select ARCH_HAS_CC_PLATFORM
1533 select X86_MEM_ENCRYPT
1535 Say yes to enable support for the encryption of system memory.
1536 This requires an AMD processor that supports Secure Memory
1539 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1540 bool "Activate AMD Secure Memory Encryption (SME) by default"
1541 depends on AMD_MEM_ENCRYPT
1543 Say yes to have system memory encrypted by default if running on
1544 an AMD processor that supports Secure Memory Encryption (SME).
1546 If set to Y, then the encryption of system memory can be
1547 deactivated with the mem_encrypt=off command line option.
1549 If set to N, then the encryption of system memory can be
1550 activated with the mem_encrypt=on command line option.
1552 # Common NUMA Features
1554 bool "NUMA Memory Allocation and Scheduler Support"
1556 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1557 default y if X86_BIGSMP
1558 select USE_PERCPU_NUMA_NODE_ID
1560 Enable NUMA (Non-Uniform Memory Access) support.
1562 The kernel will try to allocate memory used by a CPU on the
1563 local memory controller of the CPU and add some more
1564 NUMA awareness to the kernel.
1566 For 64-bit this is recommended if the system is Intel Core i7
1567 (or later), AMD Opteron, or EM64T NUMA.
1569 For 32-bit this is only needed if you boot a 32-bit
1570 kernel on a 64-bit NUMA platform.
1572 Otherwise, you should say N.
1576 prompt "Old style AMD Opteron NUMA detection"
1577 depends on X86_64 && NUMA && PCI
1579 Enable AMD NUMA node topology detection. You should say Y here if
1580 you have a multi processor AMD system. This uses an old method to
1581 read the NUMA configuration directly from the builtin Northbridge
1582 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1583 which also takes priority if both are compiled in.
1585 config X86_64_ACPI_NUMA
1587 prompt "ACPI NUMA detection"
1588 depends on X86_64 && NUMA && ACPI && PCI
1591 Enable ACPI SRAT based node topology detection.
1594 bool "NUMA emulation"
1597 Enable NUMA emulation. A flat machine will be split
1598 into virtual nodes when booted with "numa=fake=N", where N is the
1599 number of nodes. This is only useful for debugging.
1602 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1604 default "10" if MAXSMP
1605 default "6" if X86_64
1609 Specify the maximum number of NUMA Nodes available on the target
1610 system. Increases memory reserved to accommodate various tables.
1612 config ARCH_FLATMEM_ENABLE
1614 depends on X86_32 && !NUMA
1616 config ARCH_SPARSEMEM_ENABLE
1618 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1619 select SPARSEMEM_STATIC if X86_32
1620 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1622 config ARCH_SPARSEMEM_DEFAULT
1623 def_bool X86_64 || (NUMA && X86_32)
1625 config ARCH_SELECT_MEMORY_MODEL
1627 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1629 config ARCH_MEMORY_PROBE
1630 bool "Enable sysfs memory/probe interface"
1631 depends on MEMORY_HOTPLUG
1633 This option enables a sysfs memory/probe interface for testing.
1634 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1635 If you are unsure how to answer this question, answer N.
1637 config ARCH_PROC_KCORE_TEXT
1639 depends on X86_64 && PROC_KCORE
1641 config ILLEGAL_POINTER_VALUE
1644 default 0xdead000000000000 if X86_64
1646 config X86_PMEM_LEGACY_DEVICE
1649 config X86_PMEM_LEGACY
1650 tristate "Support non-standard NVDIMMs and ADR protected memory"
1651 depends on PHYS_ADDR_T_64BIT
1653 select X86_PMEM_LEGACY_DEVICE
1654 select NUMA_KEEP_MEMINFO if NUMA
1657 Treat memory marked using the non-standard e820 type of 12 as used
1658 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1659 The kernel will offer these regions to the 'pmem' driver so
1660 they can be used for persistent storage.
1665 bool "Allocate 3rd-level pagetables from highmem"
1668 The VM uses one page table entry for each page of physical memory.
1669 For systems with a lot of RAM, this can be wasteful of precious
1670 low memory. Setting this option will put user-space page table
1671 entries in high memory.
1673 config X86_CHECK_BIOS_CORRUPTION
1674 bool "Check for low memory corruption"
1676 Periodically check for memory corruption in low memory, which
1677 is suspected to be caused by BIOS. Even when enabled in the
1678 configuration, it is disabled at runtime. Enable it by
1679 setting "memory_corruption_check=1" on the kernel command
1680 line. By default it scans the low 64k of memory every 60
1681 seconds; see the memory_corruption_check_size and
1682 memory_corruption_check_period parameters in
1683 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1685 When enabled with the default parameters, this option has
1686 almost no overhead, as it reserves a relatively small amount
1687 of memory and scans it infrequently. It both detects corruption
1688 and prevents it from affecting the running system.
1690 It is, however, intended as a diagnostic tool; if repeatable
1691 BIOS-originated corruption always affects the same memory,
1692 you can use memmap= to prevent the kernel from using that
1695 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1696 bool "Set the default setting of memory_corruption_check"
1697 depends on X86_CHECK_BIOS_CORRUPTION
1700 Set whether the default state of memory_corruption_check is
1703 config MATH_EMULATION
1705 depends on MODIFY_LDT_SYSCALL
1706 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1708 Linux can emulate a math coprocessor (used for floating point
1709 operations) if you don't have one. 486DX and Pentium processors have
1710 a math coprocessor built in, 486SX and 386 do not, unless you added
1711 a 487DX or 387, respectively. (The messages during boot time can
1712 give you some hints here ["man dmesg"].) Everyone needs either a
1713 coprocessor or this emulation.
1715 If you don't have a math coprocessor, you need to say Y here; if you
1716 say Y here even though you have a coprocessor, the coprocessor will
1717 be used nevertheless. (This behavior can be changed with the kernel
1718 command line option "no387", which comes handy if your coprocessor
1719 is broken. Try "man bootparam" or see the documentation of your boot
1720 loader (lilo or loadlin) about how to pass options to the kernel at
1721 boot time.) This means that it is a good idea to say Y here if you
1722 intend to use this kernel on different machines.
1724 More information about the internals of the Linux math coprocessor
1725 emulation can be found in <file:arch/x86/math-emu/README>.
1727 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1728 kernel, it won't hurt.
1732 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1734 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1735 the Memory Type Range Registers (MTRRs) may be used to control
1736 processor access to memory ranges. This is most useful if you have
1737 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1738 allows bus write transfers to be combined into a larger transfer
1739 before bursting over the PCI/AGP bus. This can increase performance
1740 of image write operations 2.5 times or more. Saying Y here creates a
1741 /proc/mtrr file which may be used to manipulate your processor's
1742 MTRRs. Typically the X server should use this.
1744 This code has a reasonably generic interface so that similar
1745 control registers on other processors can be easily supported
1748 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1749 Registers (ARRs) which provide a similar functionality to MTRRs. For
1750 these, the ARRs are used to emulate the MTRRs.
1751 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1752 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1753 write-combining. All of these processors are supported by this code
1754 and it makes sense to say Y here if you have one of them.
1756 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1757 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1758 can lead to all sorts of problems, so it's good to say Y here.
1760 You can safely say Y even if your machine doesn't have MTRRs, you'll
1761 just add about 9 KB to your kernel.
1763 See <file:Documentation/x86/mtrr.rst> for more information.
1765 config MTRR_SANITIZER
1767 prompt "MTRR cleanup support"
1770 Convert MTRR layout from continuous to discrete, so X drivers can
1771 add writeback entries.
1773 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1774 The largest mtrr entry size for a continuous block can be set with
1779 config MTRR_SANITIZER_ENABLE_DEFAULT
1780 int "MTRR cleanup enable value (0-1)"
1783 depends on MTRR_SANITIZER
1785 Enable mtrr cleanup default value
1787 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1788 int "MTRR cleanup spare reg num (0-7)"
1791 depends on MTRR_SANITIZER
1793 mtrr cleanup spare entries default, it can be changed via
1794 mtrr_spare_reg_nr=N on the kernel command line.
1798 prompt "x86 PAT support" if EXPERT
1801 Use PAT attributes to setup page level cache control.
1803 PATs are the modern equivalents of MTRRs and are much more
1804 flexible than MTRRs.
1806 Say N here if you see bootup problems (boot crash, boot hang,
1807 spontaneous reboots) or a non-working video driver.
1811 config ARCH_USES_PG_UNCACHED
1817 prompt "x86 architectural random number generator" if EXPERT
1819 Enable the x86 architectural RDRAND instruction
1820 (Intel Bull Mountain technology) to generate random numbers.
1821 If supported, this is a high bandwidth, cryptographically
1822 secure hardware random number generator.
1826 prompt "User Mode Instruction Prevention" if EXPERT
1828 User Mode Instruction Prevention (UMIP) is a security feature in
1829 some x86 processors. If enabled, a general protection fault is
1830 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1831 executed in user mode. These instructions unnecessarily expose
1832 information about the hardware state.
1834 The vast majority of applications do not use these instructions.
1835 For the very few that do, software emulation is provided in
1836 specific cases in protected and virtual-8086 modes. Emulated
1840 # GCC >= 9 and binutils >= 2.29
1841 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1843 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1844 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1845 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1846 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1849 config X86_KERNEL_IBT
1850 prompt "Indirect Branch Tracking"
1852 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1853 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1854 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1857 Build the kernel with support for Indirect Branch Tracking, a
1858 hardware support course-grain forward-edge Control Flow Integrity
1859 protection. It enforces that all indirect calls must land on
1860 an ENDBR instruction, as such, the compiler will instrument the
1861 code with them to make this happen.
1863 In addition to building the kernel with IBT, seal all functions that
1864 are not indirect call targets, avoiding them ever becoming one.
1866 This requires LTO like objtool runs and will slow down the build. It
1867 does significantly reduce the number of ENDBR instructions in the
1870 config X86_INTEL_MEMORY_PROTECTION_KEYS
1871 prompt "Memory Protection Keys"
1873 # Note: only available in 64-bit mode
1874 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1875 select ARCH_USES_HIGH_VMA_FLAGS
1876 select ARCH_HAS_PKEYS
1878 Memory Protection Keys provides a mechanism for enforcing
1879 page-based protections, but without requiring modification of the
1880 page tables when an application changes protection domains.
1882 For details, see Documentation/core-api/protection-keys.rst
1887 prompt "TSX enable mode"
1888 depends on CPU_SUP_INTEL
1889 default X86_INTEL_TSX_MODE_OFF
1891 Intel's TSX (Transactional Synchronization Extensions) feature
1892 allows to optimize locking protocols through lock elision which
1893 can lead to a noticeable performance boost.
1895 On the other hand it has been shown that TSX can be exploited
1896 to form side channel attacks (e.g. TAA) and chances are there
1897 will be more of those attacks discovered in the future.
1899 Therefore TSX is not enabled by default (aka tsx=off). An admin
1900 might override this decision by tsx=on the command line parameter.
1901 Even with TSX enabled, the kernel will attempt to enable the best
1902 possible TAA mitigation setting depending on the microcode available
1903 for the particular machine.
1905 This option allows to set the default tsx mode between tsx=on, =off
1906 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1909 Say off if not sure, auto if TSX is in use but it should be used on safe
1910 platforms or on if TSX is in use and the security aspect of tsx is not
1913 config X86_INTEL_TSX_MODE_OFF
1916 TSX is disabled if possible - equals to tsx=off command line parameter.
1918 config X86_INTEL_TSX_MODE_ON
1921 TSX is always enabled on TSX capable HW - equals the tsx=on command
1924 config X86_INTEL_TSX_MODE_AUTO
1927 TSX is enabled on TSX capable HW that is believed to be safe against
1928 side channel attacks- equals the tsx=auto command line parameter.
1932 bool "Software Guard eXtensions (SGX)"
1933 depends on X86_64 && CPU_SUP_INTEL
1935 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"
1970 depends on $(cc-option,-mabi=ms) || X86_32
1973 This kernel feature allows a bzImage to be loaded directly
1974 by EFI firmware without the use of a bootloader.
1976 See Documentation/admin-guide/efi-stub.rst for more information.
1979 bool "EFI mixed-mode support"
1980 depends on EFI_STUB && X86_64
1982 Enabling this feature allows a 64-bit kernel to be booted
1983 on a 32-bit firmware, provided that your CPU supports 64-bit
1986 Note that it is not possible to boot a mixed-mode enabled
1987 kernel via the EFI boot stub - a bootloader that supports
1988 the EFI handover protocol must be used.
1992 source "kernel/Kconfig.hz"
1995 bool "kexec system call"
1998 kexec is a system call that implements the ability to shutdown your
1999 current kernel, and to start another kernel. It is like a reboot
2000 but it is independent of the system firmware. And like a reboot
2001 you can start any kernel with it, not just Linux.
2003 The name comes from the similarity to the exec system call.
2005 It is an ongoing process to be certain the hardware in a machine
2006 is properly shutdown, so do not be surprised if this code does not
2007 initially work for you. As of this writing the exact hardware
2008 interface is strongly in flux, so no good recommendation can be
2012 bool "kexec file based system call"
2014 select HAVE_IMA_KEXEC if IMA
2017 depends on CRYPTO_SHA256=y
2019 This is new version of kexec system call. This system call is
2020 file based and takes file descriptors as system call argument
2021 for kernel and initramfs as opposed to list of segments as
2022 accepted by previous system call.
2024 config ARCH_HAS_KEXEC_PURGATORY
2028 bool "Verify kernel signature during kexec_file_load() syscall"
2029 depends on KEXEC_FILE
2032 This option makes the kexec_file_load() syscall check for a valid
2033 signature of the kernel image. The image can still be loaded without
2034 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2035 there's a signature that we can check, then it must be valid.
2037 In addition to this option, you need to enable signature
2038 verification for the corresponding kernel image type being
2039 loaded in order for this to work.
2041 config KEXEC_SIG_FORCE
2042 bool "Require a valid signature in kexec_file_load() syscall"
2043 depends on KEXEC_SIG
2045 This option makes kernel signature verification mandatory for
2046 the kexec_file_load() syscall.
2048 config KEXEC_BZIMAGE_VERIFY_SIG
2049 bool "Enable bzImage signature verification support"
2050 depends on KEXEC_SIG
2051 depends on SIGNED_PE_FILE_VERIFICATION
2052 select SYSTEM_TRUSTED_KEYRING
2054 Enable bzImage signature verification support.
2057 bool "kernel crash dumps"
2058 depends on X86_64 || (X86_32 && HIGHMEM)
2060 Generate crash dump after being started by kexec.
2061 This should be normally only set in special crash dump kernels
2062 which are loaded in the main kernel with kexec-tools into
2063 a specially reserved region and then later executed after
2064 a crash by kdump/kexec. The crash dump kernel must be compiled
2065 to a memory address not used by the main kernel or BIOS using
2066 PHYSICAL_START, or it must be built as a relocatable image
2067 (CONFIG_RELOCATABLE=y).
2068 For more details see Documentation/admin-guide/kdump/kdump.rst
2072 depends on KEXEC && HIBERNATION
2074 Jump between original kernel and kexeced kernel and invoke
2075 code in physical address mode via KEXEC
2077 config PHYSICAL_START
2078 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2081 This gives the physical address where the kernel is loaded.
2083 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2084 bzImage will decompress itself to above physical address and
2085 run from there. Otherwise, bzImage will run from the address where
2086 it has been loaded by the boot loader and will ignore above physical
2089 In normal kdump cases one does not have to set/change this option
2090 as now bzImage can be compiled as a completely relocatable image
2091 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2092 address. This option is mainly useful for the folks who don't want
2093 to use a bzImage for capturing the crash dump and want to use a
2094 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2095 to be specifically compiled to run from a specific memory area
2096 (normally a reserved region) and this option comes handy.
2098 So if you are using bzImage for capturing the crash dump,
2099 leave the value here unchanged to 0x1000000 and set
2100 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2101 for capturing the crash dump change this value to start of
2102 the reserved region. In other words, it can be set based on
2103 the "X" value as specified in the "crashkernel=YM@XM"
2104 command line boot parameter passed to the panic-ed
2105 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2106 for more details about crash dumps.
2108 Usage of bzImage for capturing the crash dump is recommended as
2109 one does not have to build two kernels. Same kernel can be used
2110 as production kernel and capture kernel. Above option should have
2111 gone away after relocatable bzImage support is introduced. But it
2112 is present because there are users out there who continue to use
2113 vmlinux for dump capture. This option should go away down the
2116 Don't change this unless you know what you are doing.
2119 bool "Build a relocatable kernel"
2122 This builds a kernel image that retains relocation information
2123 so it can be loaded someplace besides the default 1MB.
2124 The relocations tend to make the kernel binary about 10% larger,
2125 but are discarded at runtime.
2127 One use is for the kexec on panic case where the recovery kernel
2128 must live at a different physical address than the primary
2131 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2132 it has been loaded at and the compile time physical address
2133 (CONFIG_PHYSICAL_START) is used as the minimum location.
2135 config RANDOMIZE_BASE
2136 bool "Randomize the address of the kernel image (KASLR)"
2137 depends on RELOCATABLE
2140 In support of Kernel Address Space Layout Randomization (KASLR),
2141 this randomizes the physical address at which the kernel image
2142 is decompressed and the virtual address where the kernel
2143 image is mapped, as a security feature that deters exploit
2144 attempts relying on knowledge of the location of kernel
2147 On 64-bit, the kernel physical and virtual addresses are
2148 randomized separately. The physical address will be anywhere
2149 between 16MB and the top of physical memory (up to 64TB). The
2150 virtual address will be randomized from 16MB up to 1GB (9 bits
2151 of entropy). Note that this also reduces the memory space
2152 available to kernel modules from 1.5GB to 1GB.
2154 On 32-bit, the kernel physical and virtual addresses are
2155 randomized together. They will be randomized from 16MB up to
2156 512MB (8 bits of entropy).
2158 Entropy is generated using the RDRAND instruction if it is
2159 supported. If RDTSC is supported, its value is mixed into
2160 the entropy pool as well. If neither RDRAND nor RDTSC are
2161 supported, then entropy is read from the i8254 timer. The
2162 usable entropy is limited by the kernel being built using
2163 2GB addressing, and that PHYSICAL_ALIGN must be at a
2164 minimum of 2MB. As a result, only 10 bits of entropy are
2165 theoretically possible, but the implementations are further
2166 limited due to memory layouts.
2170 # Relocation on x86 needs some additional build support
2171 config X86_NEED_RELOCS
2173 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2175 config PHYSICAL_ALIGN
2176 hex "Alignment value to which kernel should be aligned"
2178 range 0x2000 0x1000000 if X86_32
2179 range 0x200000 0x1000000 if X86_64
2181 This value puts the alignment restrictions on physical address
2182 where kernel is loaded and run from. Kernel is compiled for an
2183 address which meets above alignment restriction.
2185 If bootloader loads the kernel at a non-aligned address and
2186 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2187 address aligned to above value and run from there.
2189 If bootloader loads the kernel at a non-aligned address and
2190 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2191 load address and decompress itself to the address it has been
2192 compiled for and run from there. The address for which kernel is
2193 compiled already meets above alignment restrictions. Hence the
2194 end result is that kernel runs from a physical address meeting
2195 above alignment restrictions.
2197 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2198 this value must be a multiple of 0x200000.
2200 Don't change this unless you know what you are doing.
2202 config DYNAMIC_MEMORY_LAYOUT
2205 This option makes base addresses of vmalloc and vmemmap as well as
2206 __PAGE_OFFSET movable during boot.
2208 config RANDOMIZE_MEMORY
2209 bool "Randomize the kernel memory sections"
2211 depends on RANDOMIZE_BASE
2212 select DYNAMIC_MEMORY_LAYOUT
2213 default RANDOMIZE_BASE
2215 Randomizes the base virtual address of kernel memory sections
2216 (physical memory mapping, vmalloc & vmemmap). This security feature
2217 makes exploits relying on predictable memory locations less reliable.
2219 The order of allocations remains unchanged. Entropy is generated in
2220 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2221 configuration have in average 30,000 different possible virtual
2222 addresses for each memory section.
2226 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2227 hex "Physical memory mapping padding" if EXPERT
2228 depends on RANDOMIZE_MEMORY
2229 default "0xa" if MEMORY_HOTPLUG
2231 range 0x1 0x40 if MEMORY_HOTPLUG
2234 Define the padding in terabytes added to the existing physical
2235 memory size during kernel memory randomization. It is useful
2236 for memory hotplug support but reduces the entropy available for
2237 address randomization.
2239 If unsure, leave at the default value.
2245 config BOOTPARAM_HOTPLUG_CPU0
2246 bool "Set default setting of cpu0_hotpluggable"
2247 depends on HOTPLUG_CPU
2249 Set whether default state of cpu0_hotpluggable is on or off.
2251 Say Y here to enable CPU0 hotplug by default. If this switch
2252 is turned on, there is no need to give cpu0_hotplug kernel
2253 parameter and the CPU0 hotplug feature is enabled by default.
2255 Please note: there are two known CPU0 dependencies if you want
2256 to enable the CPU0 hotplug feature either by this switch or by
2257 cpu0_hotplug kernel parameter.
2259 First, resume from hibernate or suspend always starts from CPU0.
2260 So hibernate and suspend are prevented if CPU0 is offline.
2262 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2263 offline if any interrupt can not migrate out of CPU0. There may
2264 be other CPU0 dependencies.
2266 Please make sure the dependencies are under your control before
2267 you enable this feature.
2269 Say N if you don't want to enable CPU0 hotplug feature by default.
2270 You still can enable the CPU0 hotplug feature at boot by kernel
2271 parameter cpu0_hotplug.
2273 config DEBUG_HOTPLUG_CPU0
2275 prompt "Debug CPU0 hotplug"
2276 depends on HOTPLUG_CPU
2278 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2279 soon as possible and boots up userspace with CPU0 offlined. User
2280 can online CPU0 back after boot time.
2282 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2283 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2284 compilation or giving cpu0_hotplug kernel parameter at boot.
2290 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2291 depends on COMPAT_32
2293 Certain buggy versions of glibc will crash if they are
2294 presented with a 32-bit vDSO that is not mapped at the address
2295 indicated in its segment table.
2297 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2298 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2299 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2300 the only released version with the bug, but OpenSUSE 9
2301 contains a buggy "glibc 2.3.2".
2303 The symptom of the bug is that everything crashes on startup, saying:
2304 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2306 Saying Y here changes the default value of the vdso32 boot
2307 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2308 This works around the glibc bug but hurts performance.
2310 If unsure, say N: if you are compiling your own kernel, you
2311 are unlikely to be using a buggy version of glibc.
2314 prompt "vsyscall table for legacy applications"
2316 default LEGACY_VSYSCALL_XONLY
2318 Legacy user code that does not know how to find the vDSO expects
2319 to be able to issue three syscalls by calling fixed addresses in
2320 kernel space. Since this location is not randomized with ASLR,
2321 it can be used to assist security vulnerability exploitation.
2323 This setting can be changed at boot time via the kernel command
2324 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2325 is deprecated and can only be enabled using the kernel command
2328 On a system with recent enough glibc (2.14 or newer) and no
2329 static binaries, you can say None without a performance penalty
2330 to improve security.
2332 If unsure, select "Emulate execution only".
2334 config LEGACY_VSYSCALL_XONLY
2335 bool "Emulate execution only"
2337 The kernel traps and emulates calls into the fixed vsyscall
2338 address mapping and does not allow reads. This
2339 configuration is recommended when userspace might use the
2340 legacy vsyscall area but support for legacy binary
2341 instrumentation of legacy code is not needed. It mitigates
2342 certain uses of the vsyscall area as an ASLR-bypassing
2345 config LEGACY_VSYSCALL_NONE
2348 There will be no vsyscall mapping at all. This will
2349 eliminate any risk of ASLR bypass due to the vsyscall
2350 fixed address mapping. Attempts to use the vsyscalls
2351 will be reported to dmesg, so that either old or
2352 malicious userspace programs can be identified.
2357 bool "Built-in kernel command line"
2359 Allow for specifying boot arguments to the kernel at
2360 build time. On some systems (e.g. embedded ones), it is
2361 necessary or convenient to provide some or all of the
2362 kernel boot arguments with the kernel itself (that is,
2363 to not rely on the boot loader to provide them.)
2365 To compile command line arguments into the kernel,
2366 set this option to 'Y', then fill in the
2367 boot arguments in CONFIG_CMDLINE.
2369 Systems with fully functional boot loaders (i.e. non-embedded)
2370 should leave this option set to 'N'.
2373 string "Built-in kernel command string"
2374 depends on CMDLINE_BOOL
2377 Enter arguments here that should be compiled into the kernel
2378 image and used at boot time. If the boot loader provides a
2379 command line at boot time, it is appended to this string to
2380 form the full kernel command line, when the system boots.
2382 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2383 change this behavior.
2385 In most cases, the command line (whether built-in or provided
2386 by the boot loader) should specify the device for the root
2389 config CMDLINE_OVERRIDE
2390 bool "Built-in command line overrides boot loader arguments"
2391 depends on CMDLINE_BOOL && CMDLINE != ""
2393 Set this option to 'Y' to have the kernel ignore the boot loader
2394 command line, and use ONLY the built-in command line.
2396 This is used to work around broken boot loaders. This should
2397 be set to 'N' under normal conditions.
2399 config MODIFY_LDT_SYSCALL
2400 bool "Enable the LDT (local descriptor table)" if EXPERT
2403 Linux can allow user programs to install a per-process x86
2404 Local Descriptor Table (LDT) using the modify_ldt(2) system
2405 call. This is required to run 16-bit or segmented code such as
2406 DOSEMU or some Wine programs. It is also used by some very old
2407 threading libraries.
2409 Enabling this feature adds a small amount of overhead to
2410 context switches and increases the low-level kernel attack
2411 surface. Disabling it removes the modify_ldt(2) system call.
2413 Saying 'N' here may make sense for embedded or server kernels.
2415 config STRICT_SIGALTSTACK_SIZE
2416 bool "Enforce strict size checking for sigaltstack"
2417 depends on DYNAMIC_SIGFRAME
2419 For historical reasons MINSIGSTKSZ is a constant which became
2420 already too small with AVX512 support. Add a mechanism to
2421 enforce strict checking of the sigaltstack size against the
2422 real size of the FPU frame. This option enables the check
2423 by default. It can also be controlled via the kernel command
2424 line option 'strict_sas_size' independent of this config
2425 switch. Enabling it might break existing applications which
2426 allocate a too small sigaltstack but 'work' because they
2427 never get a signal delivered.
2429 Say 'N' unless you want to really enforce this check.
2431 source "kernel/livepatch/Kconfig"
2436 def_bool $(cc-option,-mharden-sls=all)
2438 config CC_HAS_RETURN_THUNK
2439 def_bool $(cc-option,-mfunction-return=thunk-extern)
2441 menuconfig SPECULATION_MITIGATIONS
2442 bool "Mitigations for speculative execution vulnerabilities"
2445 Say Y here to enable options which enable mitigations for
2446 speculative execution hardware vulnerabilities.
2448 If you say N, all mitigations will be disabled. You really
2449 should know what you are doing to say so.
2451 if SPECULATION_MITIGATIONS
2453 config PAGE_TABLE_ISOLATION
2454 bool "Remove the kernel mapping in user mode"
2456 depends on (X86_64 || X86_PAE)
2458 This feature reduces the number of hardware side channels by
2459 ensuring that the majority of kernel addresses are not mapped
2462 See Documentation/x86/pti.rst for more details.
2465 bool "Avoid speculative indirect branches in kernel"
2466 select OBJTOOL if HAVE_OBJTOOL
2469 Compile kernel with the retpoline compiler options to guard against
2470 kernel-to-user data leaks by avoiding speculative indirect
2471 branches. Requires a compiler with -mindirect-branch=thunk-extern
2472 support for full protection. The kernel may run slower.
2475 bool "Enable return-thunks"
2476 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2477 select OBJTOOL if HAVE_OBJTOOL
2480 Compile the kernel with the return-thunks compiler option to guard
2481 against kernel-to-user data leaks by avoiding return speculation.
2482 Requires a compiler with -mfunction-return=thunk-extern
2483 support for full protection. The kernel may run slower.
2485 config CPU_UNRET_ENTRY
2486 bool "Enable UNRET on kernel entry"
2487 depends on CPU_SUP_AMD && RETHUNK && X86_64
2490 Compile the kernel with support for the retbleed=unret mitigation.
2492 config CPU_IBPB_ENTRY
2493 bool "Enable IBPB on kernel entry"
2494 depends on CPU_SUP_AMD && X86_64
2497 Compile the kernel with support for the retbleed=ibpb mitigation.
2499 config CPU_IBRS_ENTRY
2500 bool "Enable IBRS on kernel entry"
2501 depends on CPU_SUP_INTEL && X86_64
2504 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2505 This mitigates both spectre_v2 and retbleed at great cost to
2509 bool "Mitigate Straight-Line-Speculation"
2510 depends on CC_HAS_SLS && X86_64
2511 select OBJTOOL if HAVE_OBJTOOL
2514 Compile the kernel with straight-line-speculation options to guard
2515 against straight line speculation. The kernel image might be slightly
2520 config ARCH_HAS_ADD_PAGES
2522 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2524 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2527 menu "Power management and ACPI options"
2529 config ARCH_HIBERNATION_HEADER
2531 depends on HIBERNATION
2533 source "kernel/power/Kconfig"
2535 source "drivers/acpi/Kconfig"
2542 tristate "APM (Advanced Power Management) BIOS support"
2543 depends on X86_32 && PM_SLEEP
2545 APM is a BIOS specification for saving power using several different
2546 techniques. This is mostly useful for battery powered laptops with
2547 APM compliant BIOSes. If you say Y here, the system time will be
2548 reset after a RESUME operation, the /proc/apm device will provide
2549 battery status information, and user-space programs will receive
2550 notification of APM "events" (e.g. battery status change).
2552 If you select "Y" here, you can disable actual use of the APM
2553 BIOS by passing the "apm=off" option to the kernel at boot time.
2555 Note that the APM support is almost completely disabled for
2556 machines with more than one CPU.
2558 In order to use APM, you will need supporting software. For location
2559 and more information, read <file:Documentation/power/apm-acpi.rst>
2560 and the Battery Powered Linux mini-HOWTO, available from
2561 <http://www.tldp.org/docs.html#howto>.
2563 This driver does not spin down disk drives (see the hdparm(8)
2564 manpage ("man 8 hdparm") for that), and it doesn't turn off
2565 VESA-compliant "green" monitors.
2567 This driver does not support the TI 4000M TravelMate and the ACER
2568 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2569 desktop machines also don't have compliant BIOSes, and this driver
2570 may cause those machines to panic during the boot phase.
2572 Generally, if you don't have a battery in your machine, there isn't
2573 much point in using this driver and you should say N. If you get
2574 random kernel OOPSes or reboots that don't seem to be related to
2575 anything, try disabling/enabling this option (or disabling/enabling
2578 Some other things you should try when experiencing seemingly random,
2581 1) make sure that you have enough swap space and that it is
2583 2) pass the "no-hlt" option to the kernel
2584 3) switch on floating point emulation in the kernel and pass
2585 the "no387" option to the kernel
2586 4) pass the "floppy=nodma" option to the kernel
2587 5) pass the "mem=4M" option to the kernel (thereby disabling
2588 all but the first 4 MB of RAM)
2589 6) make sure that the CPU is not over clocked.
2590 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2591 8) disable the cache from your BIOS settings
2592 9) install a fan for the video card or exchange video RAM
2593 10) install a better fan for the CPU
2594 11) exchange RAM chips
2595 12) exchange the motherboard.
2597 To compile this driver as a module, choose M here: the
2598 module will be called apm.
2602 config APM_IGNORE_USER_SUSPEND
2603 bool "Ignore USER SUSPEND"
2605 This option will ignore USER SUSPEND requests. On machines with a
2606 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2607 series notebooks, it is necessary to say Y because of a BIOS bug.
2609 config APM_DO_ENABLE
2610 bool "Enable PM at boot time"
2612 Enable APM features at boot time. From page 36 of the APM BIOS
2613 specification: "When disabled, the APM BIOS does not automatically
2614 power manage devices, enter the Standby State, enter the Suspend
2615 State, or take power saving steps in response to CPU Idle calls."
2616 This driver will make CPU Idle calls when Linux is idle (unless this
2617 feature is turned off -- see "Do CPU IDLE calls", below). This
2618 should always save battery power, but more complicated APM features
2619 will be dependent on your BIOS implementation. You may need to turn
2620 this option off if your computer hangs at boot time when using APM
2621 support, or if it beeps continuously instead of suspending. Turn
2622 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2623 T400CDT. This is off by default since most machines do fine without
2628 bool "Make CPU Idle calls when idle"
2630 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2631 On some machines, this can activate improved power savings, such as
2632 a slowed CPU clock rate, when the machine is idle. These idle calls
2633 are made after the idle loop has run for some length of time (e.g.,
2634 333 mS). On some machines, this will cause a hang at boot time or
2635 whenever the CPU becomes idle. (On machines with more than one CPU,
2636 this option does nothing.)
2638 config APM_DISPLAY_BLANK
2639 bool "Enable console blanking using APM"
2641 Enable console blanking using the APM. Some laptops can use this to
2642 turn off the LCD backlight when the screen blanker of the Linux
2643 virtual console blanks the screen. Note that this is only used by
2644 the virtual console screen blanker, and won't turn off the backlight
2645 when using the X Window system. This also doesn't have anything to
2646 do with your VESA-compliant power-saving monitor. Further, this
2647 option doesn't work for all laptops -- it might not turn off your
2648 backlight at all, or it might print a lot of errors to the console,
2649 especially if you are using gpm.
2651 config APM_ALLOW_INTS
2652 bool "Allow interrupts during APM BIOS calls"
2654 Normally we disable external interrupts while we are making calls to
2655 the APM BIOS as a measure to lessen the effects of a badly behaving
2656 BIOS implementation. The BIOS should reenable interrupts if it
2657 needs to. Unfortunately, some BIOSes do not -- especially those in
2658 many of the newer IBM Thinkpads. If you experience hangs when you
2659 suspend, try setting this to Y. Otherwise, say N.
2663 source "drivers/cpufreq/Kconfig"
2665 source "drivers/cpuidle/Kconfig"
2667 source "drivers/idle/Kconfig"
2671 menu "Bus options (PCI etc.)"
2674 prompt "PCI access mode"
2675 depends on X86_32 && PCI
2678 On PCI systems, the BIOS can be used to detect the PCI devices and
2679 determine their configuration. However, some old PCI motherboards
2680 have BIOS bugs and may crash if this is done. Also, some embedded
2681 PCI-based systems don't have any BIOS at all. Linux can also try to
2682 detect the PCI hardware directly without using the BIOS.
2684 With this option, you can specify how Linux should detect the
2685 PCI devices. If you choose "BIOS", the BIOS will be used,
2686 if you choose "Direct", the BIOS won't be used, and if you
2687 choose "MMConfig", then PCI Express MMCONFIG will be used.
2688 If you choose "Any", the kernel will try MMCONFIG, then the
2689 direct access method and falls back to the BIOS if that doesn't
2690 work. If unsure, go with the default, which is "Any".
2695 config PCI_GOMMCONFIG
2712 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2714 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2717 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2720 bool "Support mmconfig PCI config space access" if X86_64
2722 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2723 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2727 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2731 depends on PCI && XEN
2733 config MMCONF_FAM10H
2735 depends on X86_64 && PCI_MMCONFIG && ACPI
2737 config PCI_CNB20LE_QUIRK
2738 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2741 Read the PCI windows out of the CNB20LE host bridge. This allows
2742 PCI hotplug to work on systems with the CNB20LE chipset which do
2745 There's no public spec for this chipset, and this functionality
2746 is known to be incomplete.
2748 You should say N unless you know you need this.
2751 bool "ISA bus support on modern systems" if EXPERT
2753 Expose ISA bus device drivers and options available for selection and
2754 configuration. Enable this option if your target machine has an ISA
2755 bus. ISA is an older system, displaced by PCI and newer bus
2756 architectures -- if your target machine is modern, it probably does
2757 not have an ISA bus.
2761 # x86_64 have no ISA slots, but can have ISA-style DMA.
2763 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2766 Enables ISA-style DMA support for devices requiring such controllers.
2774 Find out whether you have ISA slots on your motherboard. ISA is the
2775 name of a bus system, i.e. the way the CPU talks to the other stuff
2776 inside your box. Other bus systems are PCI, EISA, MicroChannel
2777 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2778 newer boards don't support it. If you have ISA, say Y, otherwise N.
2781 tristate "NatSemi SCx200 support"
2783 This provides basic support for National Semiconductor's
2784 (now AMD's) Geode processors. The driver probes for the
2785 PCI-IDs of several on-chip devices, so its a good dependency
2786 for other scx200_* drivers.
2788 If compiled as a module, the driver is named scx200.
2790 config SCx200HR_TIMER
2791 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2795 This driver provides a clocksource built upon the on-chip
2796 27MHz high-resolution timer. Its also a workaround for
2797 NSC Geode SC-1100's buggy TSC, which loses time when the
2798 processor goes idle (as is done by the scheduler). The
2799 other workaround is idle=poll boot option.
2802 bool "One Laptop Per Child support"
2810 Add support for detecting the unique features of the OLPC
2814 bool "OLPC XO-1 Power Management"
2815 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2817 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2820 bool "OLPC XO-1 Real Time Clock"
2821 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2823 Add support for the XO-1 real time clock, which can be used as a
2824 programmable wakeup source.
2827 bool "OLPC XO-1 SCI extras"
2828 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2832 Add support for SCI-based features of the OLPC XO-1 laptop:
2833 - EC-driven system wakeups
2837 - AC adapter status updates
2838 - Battery status updates
2840 config OLPC_XO15_SCI
2841 bool "OLPC XO-1.5 SCI extras"
2842 depends on OLPC && ACPI
2845 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2846 - EC-driven system wakeups
2847 - AC adapter status updates
2848 - Battery status updates
2851 bool "PCEngines ALIX System Support (LED setup)"
2854 This option enables system support for the PCEngines ALIX.
2855 At present this just sets up LEDs for GPIO control on
2856 ALIX2/3/6 boards. However, other system specific setup should
2859 Note: You must still enable the drivers for GPIO and LED support
2860 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2862 Note: You have to set alix.force=1 for boards with Award BIOS.
2865 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2868 This option enables system support for the Soekris Engineering net5501.
2871 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2875 This option enables system support for the Traverse Technologies GEOS.
2878 bool "Technologic Systems TS-5500 platform support"
2880 select CHECK_SIGNATURE
2884 This option enables system support for the Technologic Systems TS-5500.
2890 depends on CPU_SUP_AMD && PCI
2894 menu "Binary Emulations"
2896 config IA32_EMULATION
2897 bool "IA32 Emulation"
2899 select ARCH_WANT_OLD_COMPAT_IPC
2901 select COMPAT_OLD_SIGACTION
2903 Include code to run legacy 32-bit programs under a
2904 64-bit kernel. You should likely turn this on, unless you're
2905 100% sure that you don't have any 32-bit programs left.
2908 bool "x32 ABI for 64-bit mode"
2910 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2911 # compressed debug sections to x86_x32 properly:
2912 # https://github.com/ClangBuiltLinux/linux/issues/514
2913 # https://github.com/ClangBuiltLinux/linux/issues/1141
2914 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2916 Include code to run binaries for the x32 native 32-bit ABI
2917 for 64-bit processors. An x32 process gets access to the
2918 full 64-bit register file and wide data path while leaving
2919 pointers at 32 bits for smaller memory footprint.
2923 depends on IA32_EMULATION || X86_32
2925 select OLD_SIGSUSPEND3
2929 depends on IA32_EMULATION || X86_X32_ABI
2931 config COMPAT_FOR_U64_ALIGNMENT
2937 config HAVE_ATOMIC_IOMAP
2941 source "arch/x86/kvm/Kconfig"
2943 source "arch/x86/Kconfig.assembler"