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_DEBUG_WX
98 select ARCH_HAS_ZONE_DMA_SET if EXPERT
99 select ARCH_HAVE_NMI_SAFE_CMPXCHG
100 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
101 select ARCH_MIGHT_HAVE_PC_PARPORT
102 select ARCH_MIGHT_HAVE_PC_SERIO
103 select ARCH_STACKWALK
104 select ARCH_SUPPORTS_ACPI
105 select ARCH_SUPPORTS_ATOMIC_RMW
106 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
107 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
108 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
109 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
110 select ARCH_SUPPORTS_CFI_CLANG if X86_64
111 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
112 select ARCH_SUPPORTS_LTO_CLANG
113 select ARCH_SUPPORTS_LTO_CLANG_THIN
114 select ARCH_USE_BUILTIN_BSWAP
115 select ARCH_USE_MEMTEST
116 select ARCH_USE_QUEUED_RWLOCKS
117 select ARCH_USE_QUEUED_SPINLOCKS
118 select ARCH_USE_SYM_ANNOTATIONS
119 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
120 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
121 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
122 select ARCH_WANTS_NO_INSTR
123 select ARCH_WANT_GENERAL_HUGETLB
124 select ARCH_WANT_HUGE_PMD_SHARE
125 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
126 select ARCH_WANT_LD_ORPHAN_WARN
127 select ARCH_WANTS_THP_SWAP if X86_64
128 select ARCH_HAS_PARANOID_L1D_FLUSH
129 select BUILDTIME_TABLE_SORT
131 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
132 select CLOCKSOURCE_WATCHDOG
133 select DCACHE_WORD_ACCESS
134 select DYNAMIC_SIGFRAME
135 select EDAC_ATOMIC_SCRUB
137 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
138 select GENERIC_CLOCKEVENTS_MIN_ADJUST
139 select GENERIC_CMOS_UPDATE
140 select GENERIC_CPU_AUTOPROBE
141 select GENERIC_CPU_VULNERABILITIES
142 select GENERIC_EARLY_IOREMAP
145 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
146 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
147 select GENERIC_IRQ_MIGRATION if SMP
148 select GENERIC_IRQ_PROBE
149 select GENERIC_IRQ_RESERVATION_MODE
150 select GENERIC_IRQ_SHOW
151 select GENERIC_PENDING_IRQ if SMP
152 select GENERIC_PTDUMP
153 select GENERIC_SMP_IDLE_THREAD
154 select GENERIC_TIME_VSYSCALL
155 select GENERIC_GETTIMEOFDAY
156 select GENERIC_VDSO_TIME_NS
157 select GUP_GET_PTE_LOW_HIGH if X86_PAE
158 select HARDIRQS_SW_RESEND
159 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
160 select HAVE_ACPI_APEI if ACPI
161 select HAVE_ACPI_APEI_NMI if ACPI
162 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
163 select HAVE_ARCH_AUDITSYSCALL
164 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
165 select HAVE_ARCH_HUGE_VMALLOC if X86_64
166 select HAVE_ARCH_JUMP_LABEL
167 select HAVE_ARCH_JUMP_LABEL_RELATIVE
168 select HAVE_ARCH_KASAN if X86_64
169 select HAVE_ARCH_KASAN_VMALLOC if X86_64
170 select HAVE_ARCH_KFENCE
171 select HAVE_ARCH_KGDB
172 select HAVE_ARCH_MMAP_RND_BITS if MMU
173 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
174 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
175 select HAVE_ARCH_PREL32_RELOCATIONS
176 select HAVE_ARCH_SECCOMP_FILTER
177 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
178 select HAVE_ARCH_STACKLEAK
179 select HAVE_ARCH_TRACEHOOK
180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
181 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
182 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
183 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
184 select HAVE_ARCH_VMAP_STACK if X86_64
185 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
186 select HAVE_ARCH_WITHIN_STACK_FRAMES
187 select HAVE_ASM_MODVERSIONS
188 select HAVE_CMPXCHG_DOUBLE
189 select HAVE_CMPXCHG_LOCAL
190 select HAVE_CONTEXT_TRACKING_USER if X86_64
191 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
192 select HAVE_C_RECORDMCOUNT
193 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
194 select HAVE_BUILDTIME_MCOUNT_SORT
195 select HAVE_DEBUG_KMEMLEAK
196 select HAVE_DMA_CONTIGUOUS
197 select HAVE_DYNAMIC_FTRACE
198 select HAVE_DYNAMIC_FTRACE_WITH_REGS
199 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
200 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
201 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
202 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
204 select HAVE_EFFICIENT_UNALIGNED_ACCESS
206 select HAVE_EXIT_THREAD
208 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
209 select HAVE_FTRACE_MCOUNT_RECORD
210 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
211 select HAVE_FUNCTION_TRACER
212 select HAVE_GCC_PLUGINS
213 select HAVE_HW_BREAKPOINT
214 select HAVE_IOREMAP_PROT
215 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
216 select HAVE_IRQ_TIME_ACCOUNTING
217 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
218 select HAVE_KERNEL_BZIP2
219 select HAVE_KERNEL_GZIP
220 select HAVE_KERNEL_LZ4
221 select HAVE_KERNEL_LZMA
222 select HAVE_KERNEL_LZO
223 select HAVE_KERNEL_XZ
224 select HAVE_KERNEL_ZSTD
226 select HAVE_KPROBES_ON_FTRACE
227 select HAVE_FUNCTION_ERROR_INJECTION
228 select HAVE_KRETPROBES
231 select HAVE_LIVEPATCH if X86_64
232 select HAVE_MIXED_BREAKPOINTS_REGS
233 select HAVE_MOD_ARCH_SPECIFIC
236 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
238 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
239 select HAVE_OBJTOOL if X86_64
240 select HAVE_OPTPROBES
241 select HAVE_PCSPKR_PLATFORM
242 select HAVE_PERF_EVENTS
243 select HAVE_PERF_EVENTS_NMI
244 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
246 select HAVE_PERF_REGS
247 select HAVE_PERF_USER_STACK_DUMP
248 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
249 select MMU_GATHER_MERGE_VMAS
250 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
251 select HAVE_REGS_AND_STACK_ACCESS_API
252 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
253 select HAVE_FUNCTION_ARG_ACCESS_API
254 select HAVE_SETUP_PER_CPU_AREA
255 select HAVE_SOFTIRQ_ON_OWN_STACK
256 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
257 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
258 select HAVE_STATIC_CALL
259 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
260 select HAVE_PREEMPT_DYNAMIC_CALL
262 select HAVE_RUST if X86_64
263 select HAVE_SYSCALL_TRACEPOINTS
264 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
265 select HAVE_UNSTABLE_SCHED_CLOCK
266 select HAVE_USER_RETURN_NOTIFIER
267 select HAVE_GENERIC_VDSO
268 select HOTPLUG_SMT if SMP
269 select IRQ_FORCED_THREADING
270 select NEED_PER_CPU_EMBED_FIRST_CHUNK
271 select NEED_PER_CPU_PAGE_FIRST_CHUNK
272 select NEED_SG_DMA_LENGTH
273 select PCI_DOMAINS if PCI
274 select PCI_LOCKLESS_CONFIG if PCI
277 select RTC_MC146818_LIB
280 select SYSCTL_EXCEPTION_TRACE
281 select THREAD_INFO_IN_TASK
282 select TRACE_IRQFLAGS_SUPPORT
283 select TRACE_IRQFLAGS_NMI_SUPPORT
284 select USER_STACKTRACE_SUPPORT
285 select HAVE_ARCH_KCSAN if X86_64
286 select X86_FEATURE_NAMES if PROC_FS
287 select PROC_PID_ARCH_STATUS if PROC_FS
288 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
289 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
290 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
292 config INSTRUCTION_DECODER
294 depends on KPROBES || PERF_EVENTS || UPROBES
298 default "elf32-i386" if X86_32
299 default "elf64-x86-64" if X86_64
301 config LOCKDEP_SUPPORT
304 config STACKTRACE_SUPPORT
310 config ARCH_MMAP_RND_BITS_MIN
314 config ARCH_MMAP_RND_BITS_MAX
318 config ARCH_MMAP_RND_COMPAT_BITS_MIN
321 config ARCH_MMAP_RND_COMPAT_BITS_MAX
327 config GENERIC_ISA_DMA
329 depends on ISA_DMA_API
334 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
336 config GENERIC_BUG_RELATIVE_POINTERS
339 config ARCH_MAY_HAVE_PC_FDC
341 depends on ISA_DMA_API
343 config GENERIC_CALIBRATE_DELAY
346 config ARCH_HAS_CPU_RELAX
349 config ARCH_HIBERNATION_POSSIBLE
354 default 1024 if X86_64
357 config ARCH_SUSPEND_POSSIBLE
363 config KASAN_SHADOW_OFFSET
366 default 0xdffffc0000000000
368 config HAVE_INTEL_TXT
370 depends on INTEL_IOMMU && ACPI
374 depends on X86_32 && SMP
378 depends on X86_64 && SMP
380 config ARCH_SUPPORTS_UPROBES
383 config FIX_EARLYCON_MEM
386 config DYNAMIC_PHYSICAL_MASK
389 config PGTABLE_LEVELS
391 default 5 if X86_5LEVEL
396 config CC_HAS_SANE_STACKPROTECTOR
398 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
399 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
401 We have to make sure stack protector is unconditionally disabled if
402 the compiler produces broken code or if it does not let us control
403 the segment on 32-bit kernels.
405 menu "Processor type and features"
408 bool "Symmetric multi-processing support"
410 This enables support for systems with more than one CPU. If you have
411 a system with only one CPU, say N. If you have a system with more
414 If you say N here, the kernel will run on uni- and multiprocessor
415 machines, but will use only one CPU of a multiprocessor machine. If
416 you say Y here, the kernel will run on many, but not all,
417 uniprocessor machines. On a uniprocessor machine, the kernel
418 will run faster if you say N here.
420 Note that if you say Y here and choose architecture "586" or
421 "Pentium" under "Processor family", the kernel will not work on 486
422 architectures. Similarly, multiprocessor kernels for the "PPro"
423 architecture may not work on all Pentium based boards.
425 People using multiprocessor machines who say Y here should also say
426 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
427 Management" code will be disabled if you say Y here.
429 See also <file:Documentation/x86/i386/IO-APIC.rst>,
430 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
431 <http://www.tldp.org/docs.html#howto>.
433 If you don't know what to do here, say N.
435 config X86_FEATURE_NAMES
436 bool "Processor feature human-readable names" if EMBEDDED
439 This option compiles in a table of x86 feature bits and corresponding
440 names. This is required to support /proc/cpuinfo and a few kernel
441 messages. You can disable this to save space, at the expense of
442 making those few kernel messages show numeric feature bits instead.
447 bool "Support x2apic"
448 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
450 This enables x2apic support on CPUs that have this feature.
452 This allows 32-bit apic IDs (so it can support very large systems),
453 and accesses the local apic via MSRs not via mmio.
455 Some Intel systems circa 2022 and later are locked into x2APIC mode
456 and can not fall back to the legacy APIC modes if SGX or TDX are
457 enabled in the BIOS. They will be unable to boot without enabling
460 If you don't know what to do here, say N.
463 bool "Enable MPS table" if ACPI
465 depends on X86_LOCAL_APIC
467 For old smp systems that do not have proper acpi support. Newer systems
468 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
472 depends on X86_GOLDFISH
474 config X86_CPU_RESCTRL
475 bool "x86 CPU resource control support"
476 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
478 select PROC_CPU_RESCTRL if PROC_FS
480 Enable x86 CPU resource control support.
482 Provide support for the allocation and monitoring of system resources
485 Intel calls this Intel Resource Director Technology
486 (Intel(R) RDT). More information about RDT can be found in the
487 Intel x86 Architecture Software Developer Manual.
489 AMD calls this AMD Platform Quality of Service (AMD QoS).
490 More information about AMD QoS can be found in the AMD64 Technology
491 Platform Quality of Service Extensions manual.
497 bool "Support for big SMP systems with more than 8 CPUs"
500 This option is needed for the systems that have more than 8 CPUs.
502 config X86_EXTENDED_PLATFORM
503 bool "Support for extended (non-PC) x86 platforms"
506 If you disable this option then the kernel will only support
507 standard PC platforms. (which covers the vast majority of
510 If you enable this option then you'll be able to select support
511 for the following (non-PC) 32 bit x86 platforms:
512 Goldfish (Android emulator)
515 SGI 320/540 (Visual Workstation)
516 STA2X11-based (e.g. Northville)
517 Moorestown MID devices
519 If you have one of these systems, or if you want to build a
520 generic distribution kernel, say Y here - otherwise say N.
524 config X86_EXTENDED_PLATFORM
525 bool "Support for extended (non-PC) x86 platforms"
528 If you disable this option then the kernel will only support
529 standard PC platforms. (which covers the vast majority of
532 If you enable this option then you'll be able to select support
533 for the following (non-PC) 64 bit x86 platforms:
538 If you have one of these systems, or if you want to build a
539 generic distribution kernel, say Y here - otherwise say N.
541 # This is an alphabetically sorted list of 64 bit extended platforms
542 # Please maintain the alphabetic order if and when there are additions
544 bool "Numascale NumaChip"
546 depends on X86_EXTENDED_PLATFORM
549 depends on X86_X2APIC
550 depends on PCI_MMCONFIG
552 Adds support for Numascale NumaChip large-SMP systems. Needed to
553 enable more than ~168 cores.
554 If you don't have one of these, you should say N here.
558 select HYPERVISOR_GUEST
560 depends on X86_64 && PCI
561 depends on X86_EXTENDED_PLATFORM
564 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
565 supposed to run on these EM64T-based machines. Only choose this option
566 if you have one of these machines.
569 bool "SGI Ultraviolet"
571 depends on X86_EXTENDED_PLATFORM
574 depends on KEXEC_CORE
575 depends on X86_X2APIC
578 This option is needed in order to support SGI Ultraviolet systems.
579 If you don't have one of these, you should say N here.
581 # Following is an alphabetically sorted list of 32 bit extended platforms
582 # Please maintain the alphabetic order if and when there are additions
585 bool "Goldfish (Virtual Platform)"
586 depends on X86_EXTENDED_PLATFORM
588 Enable support for the Goldfish virtual platform used primarily
589 for Android development. Unless you are building for the Android
590 Goldfish emulator say N here.
593 bool "CE4100 TV platform"
595 depends on PCI_GODIRECT
596 depends on X86_IO_APIC
598 depends on X86_EXTENDED_PLATFORM
599 select X86_REBOOTFIXUPS
601 select OF_EARLY_FLATTREE
603 Select for the Intel CE media processor (CE4100) SOC.
604 This option compiles in support for the CE4100 SOC for settop
605 boxes and media devices.
608 bool "Intel MID platform support"
609 depends on X86_EXTENDED_PLATFORM
610 depends on X86_PLATFORM_DEVICES
612 depends on X86_64 || (PCI_GOANY && X86_32)
613 depends on X86_IO_APIC
618 Select to build a kernel capable of supporting Intel MID (Mobile
619 Internet Device) platform systems which do not have the PCI legacy
620 interfaces. If you are building for a PC class system say N here.
622 Intel MID platforms are based on an Intel processor and chipset which
623 consume less power than most of the x86 derivatives.
625 config X86_INTEL_QUARK
626 bool "Intel Quark platform support"
628 depends on X86_EXTENDED_PLATFORM
629 depends on X86_PLATFORM_DEVICES
633 depends on X86_IO_APIC
638 Select to include support for Quark X1000 SoC.
639 Say Y here if you have a Quark based system such as the Arduino
640 compatible Intel Galileo.
642 config X86_INTEL_LPSS
643 bool "Intel Low Power Subsystem Support"
644 depends on X86 && ACPI && PCI
649 Select to build support for Intel Low Power Subsystem such as
650 found on Intel Lynxpoint PCH. Selecting this option enables
651 things like clock tree (common clock framework) and pincontrol
652 which are needed by the LPSS peripheral drivers.
654 config X86_AMD_PLATFORM_DEVICE
655 bool "AMD ACPI2Platform devices support"
660 Select to interpret AMD specific ACPI device to platform device
661 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
662 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
663 implemented under PINCTRL subsystem.
666 tristate "Intel SoC IOSF Sideband support for SoC platforms"
669 This option enables sideband register access support for Intel SoC
670 platforms. On these platforms the IOSF sideband is used in lieu of
671 MSR's for some register accesses, mostly but not limited to thermal
672 and power. Drivers may query the availability of this device to
673 determine if they need the sideband in order to work on these
674 platforms. The sideband is available on the following SoC products.
675 This list is not meant to be exclusive.
680 You should say Y if you are running a kernel on one of these SoC's.
682 config IOSF_MBI_DEBUG
683 bool "Enable IOSF sideband access through debugfs"
684 depends on IOSF_MBI && DEBUG_FS
686 Select this option to expose the IOSF sideband access registers (MCR,
687 MDR, MCRX) through debugfs to write and read register information from
688 different units on the SoC. This is most useful for obtaining device
689 state information for debug and analysis. As this is a general access
690 mechanism, users of this option would have specific knowledge of the
691 device they want to access.
693 If you don't require the option or are in doubt, say N.
696 bool "RDC R-321x SoC"
698 depends on X86_EXTENDED_PLATFORM
700 select X86_REBOOTFIXUPS
702 This option is needed for RDC R-321x system-on-chip, also known
704 If you don't have one of these chips, you should say N here.
706 config X86_32_NON_STANDARD
707 bool "Support non-standard 32-bit SMP architectures"
708 depends on X86_32 && SMP
709 depends on X86_EXTENDED_PLATFORM
711 This option compiles in the bigsmp and STA2X11 default
712 subarchitectures. It is intended for a generic binary
713 kernel. If you select them all, kernel will probe it one by
714 one and will fallback to default.
716 # Alphabetically sorted list of Non standard 32 bit platforms
718 config X86_SUPPORTS_MEMORY_FAILURE
720 # MCE code calls memory_failure():
722 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
723 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
724 depends on X86_64 || !SPARSEMEM
725 select ARCH_SUPPORTS_MEMORY_FAILURE
728 bool "STA2X11 Companion Chip Support"
729 depends on X86_32_NON_STANDARD && PCI
734 This adds support for boards based on the STA2X11 IO-Hub,
735 a.k.a. "ConneXt". The chip is used in place of the standard
736 PC chipset, so all "standard" peripherals are missing. If this
737 option is selected the kernel will still be able to boot on
738 standard PC machines.
741 tristate "Eurobraille/Iris poweroff module"
744 The Iris machines from EuroBraille do not have APM or ACPI support
745 to shut themselves down properly. A special I/O sequence is
746 needed to do so, which is what this module does at
749 This is only for Iris machines from EuroBraille.
753 config SCHED_OMIT_FRAME_POINTER
755 prompt "Single-depth WCHAN output"
758 Calculate simpler /proc/<PID>/wchan values. If this option
759 is disabled then wchan values will recurse back to the
760 caller function. This provides more accurate wchan values,
761 at the expense of slightly more scheduling overhead.
763 If in doubt, say "Y".
765 menuconfig HYPERVISOR_GUEST
766 bool "Linux guest support"
768 Say Y here to enable options for running Linux under various hyper-
769 visors. This option enables basic hypervisor detection and platform
772 If you say N, all options in this submenu will be skipped and
773 disabled, and Linux guest support won't be built in.
778 bool "Enable paravirtualization code"
779 depends on HAVE_STATIC_CALL
781 This changes the kernel so it can modify itself when it is run
782 under a hypervisor, potentially improving performance significantly
783 over full virtualization. However, when run without a hypervisor
784 the kernel is theoretically slower and slightly larger.
789 config PARAVIRT_DEBUG
790 bool "paravirt-ops debugging"
791 depends on PARAVIRT && DEBUG_KERNEL
793 Enable to debug paravirt_ops internals. Specifically, BUG if
794 a paravirt_op is missing when it is called.
796 config PARAVIRT_SPINLOCKS
797 bool "Paravirtualization layer for spinlocks"
798 depends on PARAVIRT && SMP
800 Paravirtualized spinlocks allow a pvops backend to replace the
801 spinlock implementation with something virtualization-friendly
802 (for example, block the virtual CPU rather than spinning).
804 It has a minimal impact on native kernels and gives a nice performance
805 benefit on paravirtualized KVM / Xen kernels.
807 If you are unsure how to answer this question, answer Y.
809 config X86_HV_CALLBACK_VECTOR
812 source "arch/x86/xen/Kconfig"
815 bool "KVM Guest support (including kvmclock)"
817 select PARAVIRT_CLOCK
818 select ARCH_CPUIDLE_HALTPOLL
819 select X86_HV_CALLBACK_VECTOR
822 This option enables various optimizations for running under the KVM
823 hypervisor. It includes a paravirtualized clock, so that instead
824 of relying on a PIT (or probably other) emulation by the
825 underlying device model, the host provides the guest with
826 timing infrastructure such as time of day, and system time
828 config ARCH_CPUIDLE_HALTPOLL
830 prompt "Disable host haltpoll when loading haltpoll driver"
832 If virtualized under KVM, disable host haltpoll.
835 bool "Support for running PVH guests"
837 This option enables the PVH entry point for guest virtual machines
838 as specified in the x86/HVM direct boot ABI.
840 config PARAVIRT_TIME_ACCOUNTING
841 bool "Paravirtual steal time accounting"
844 Select this option to enable fine granularity task steal time
845 accounting. Time spent executing other tasks in parallel with
846 the current vCPU is discounted from the vCPU power. To account for
847 that, there can be a small performance impact.
849 If in doubt, say N here.
851 config PARAVIRT_CLOCK
854 config JAILHOUSE_GUEST
855 bool "Jailhouse non-root cell support"
856 depends on X86_64 && PCI
859 This option allows to run Linux as guest in a Jailhouse non-root
860 cell. You can leave this option disabled if you only want to start
861 Jailhouse and run Linux afterwards in the root cell.
864 bool "ACRN Guest support"
866 select X86_HV_CALLBACK_VECTOR
868 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
869 a flexible, lightweight reference open-source hypervisor, built with
870 real-time and safety-criticality in mind. It is built for embedded
871 IOT with small footprint and real-time features. More details can be
872 found in https://projectacrn.org/.
874 config INTEL_TDX_GUEST
875 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
876 depends on X86_64 && CPU_SUP_INTEL
877 depends on X86_X2APIC
878 select ARCH_HAS_CC_PLATFORM
879 select X86_MEM_ENCRYPT
882 Support running as a guest under Intel TDX. Without this support,
883 the guest kernel can not boot or run under TDX.
884 TDX includes memory encryption and integrity capabilities
885 which protect the confidentiality and integrity of guest
886 memory contents and CPU state. TDX guests are protected from
887 some attacks from the VMM.
889 endif # HYPERVISOR_GUEST
891 source "arch/x86/Kconfig.cpu"
895 prompt "HPET Timer Support" if X86_32
897 Use the IA-PC HPET (High Precision Event Timer) to manage
898 time in preference to the PIT and RTC, if a HPET is
900 HPET is the next generation timer replacing legacy 8254s.
901 The HPET provides a stable time base on SMP
902 systems, unlike the TSC, but it is more expensive to access,
903 as it is off-chip. The interface used is documented
904 in the HPET spec, revision 1.
906 You can safely choose Y here. However, HPET will only be
907 activated if the platform and the BIOS support this feature.
908 Otherwise the 8254 will be used for timing services.
910 Choose N to continue using the legacy 8254 timer.
912 config HPET_EMULATE_RTC
914 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
916 # Mark as expert because too many people got it wrong.
917 # The code disables itself when not needed.
920 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
921 bool "Enable DMI scanning" if EXPERT
923 Enabled scanning of DMI to identify machine quirks. Say Y
924 here unless you have verified that your setup is not
925 affected by entries in the DMI blacklist. Required by PNP
929 bool "Old AMD GART IOMMU support"
933 depends on X86_64 && PCI && AMD_NB
935 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
936 GART based hardware IOMMUs.
938 The GART supports full DMA access for devices with 32-bit access
939 limitations, on systems with more than 3 GB. This is usually needed
940 for USB, sound, many IDE/SATA chipsets and some other devices.
942 Newer systems typically have a modern AMD IOMMU, supported via
943 the CONFIG_AMD_IOMMU=y config option.
945 In normal configurations this driver is only active when needed:
946 there's more than 3 GB of memory and the system contains a
947 32-bit limited device.
951 config BOOT_VESA_SUPPORT
954 If true, at least one selected framebuffer driver can take advantage
955 of VESA video modes set at an early boot stage via the vga= parameter.
958 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
959 depends on X86_64 && SMP && DEBUG_KERNEL
960 select CPUMASK_OFFSTACK
962 Enable maximum number of CPUS and NUMA Nodes for this architecture.
966 # The maximum number of CPUs supported:
968 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
969 # and which can be configured interactively in the
970 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
972 # The ranges are different on 32-bit and 64-bit kernels, depending on
973 # hardware capabilities and scalability features of the kernel.
975 # ( If MAXSMP is enabled we just use the highest possible value and disable
976 # interactive configuration. )
979 config NR_CPUS_RANGE_BEGIN
981 default NR_CPUS_RANGE_END if MAXSMP
985 config NR_CPUS_RANGE_END
988 default 64 if SMP && X86_BIGSMP
989 default 8 if SMP && !X86_BIGSMP
992 config NR_CPUS_RANGE_END
995 default 8192 if SMP && CPUMASK_OFFSTACK
996 default 512 if SMP && !CPUMASK_OFFSTACK
999 config NR_CPUS_DEFAULT
1002 default 32 if X86_BIGSMP
1006 config NR_CPUS_DEFAULT
1009 default 8192 if MAXSMP
1014 int "Maximum number of CPUs" if SMP && !MAXSMP
1015 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1016 default NR_CPUS_DEFAULT
1018 This allows you to specify the maximum number of CPUs which this
1019 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1020 supported value is 8192, otherwise the maximum value is 512. The
1021 minimum value which makes sense is 2.
1023 This is purely to save memory: each supported CPU adds about 8KB
1024 to the kernel image.
1026 config SCHED_CLUSTER
1027 bool "Cluster scheduler support"
1031 Cluster scheduler support improves the CPU scheduler's decision
1032 making when dealing with machines that have clusters of CPUs.
1033 Cluster usually means a couple of CPUs which are placed closely
1034 by sharing mid-level caches, last-level cache tags or internal
1042 prompt "Multi-core scheduler support"
1045 Multi-core scheduler support improves the CPU scheduler's decision
1046 making when dealing with multi-core CPU chips at a cost of slightly
1047 increased overhead in some places. If unsure say N here.
1049 config SCHED_MC_PRIO
1050 bool "CPU core priorities scheduler support"
1051 depends on SCHED_MC && CPU_SUP_INTEL
1052 select X86_INTEL_PSTATE
1056 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1057 core ordering determined at manufacturing time, which allows
1058 certain cores to reach higher turbo frequencies (when running
1059 single threaded workloads) than others.
1061 Enabling this kernel feature teaches the scheduler about
1062 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1063 scheduler's CPU selection logic accordingly, so that higher
1064 overall system performance can be achieved.
1066 This feature will have no effect on CPUs without this feature.
1068 If unsure say Y here.
1072 depends on !SMP && X86_LOCAL_APIC
1075 bool "Local APIC support on uniprocessors" if !PCI_MSI
1077 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1079 A local APIC (Advanced Programmable Interrupt Controller) is an
1080 integrated interrupt controller in the CPU. If you have a single-CPU
1081 system which has a processor with a local APIC, you can say Y here to
1082 enable and use it. If you say Y here even though your machine doesn't
1083 have a local APIC, then the kernel will still run with no slowdown at
1084 all. The local APIC supports CPU-generated self-interrupts (timer,
1085 performance counters), and the NMI watchdog which detects hard
1088 config X86_UP_IOAPIC
1089 bool "IO-APIC support on uniprocessors"
1090 depends on X86_UP_APIC
1092 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1093 SMP-capable replacement for PC-style interrupt controllers. Most
1094 SMP systems and many recent uniprocessor systems have one.
1096 If you have a single-CPU system with an IO-APIC, you can say Y here
1097 to use it. If you say Y here even though your machine doesn't have
1098 an IO-APIC, then the kernel will still run with no slowdown at all.
1100 config X86_LOCAL_APIC
1102 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1103 select IRQ_DOMAIN_HIERARCHY
1104 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1108 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1110 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1111 bool "Reroute for broken boot IRQs"
1112 depends on X86_IO_APIC
1114 This option enables a workaround that fixes a source of
1115 spurious interrupts. This is recommended when threaded
1116 interrupt handling is used on systems where the generation of
1117 superfluous "boot interrupts" cannot be disabled.
1119 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1120 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1121 kernel does during interrupt handling). On chipsets where this
1122 boot IRQ generation cannot be disabled, this workaround keeps
1123 the original IRQ line masked so that only the equivalent "boot
1124 IRQ" is delivered to the CPUs. The workaround also tells the
1125 kernel to set up the IRQ handler on the boot IRQ line. In this
1126 way only one interrupt is delivered to the kernel. Otherwise
1127 the spurious second interrupt may cause the kernel to bring
1128 down (vital) interrupt lines.
1130 Only affects "broken" chipsets. Interrupt sharing may be
1131 increased on these systems.
1134 bool "Machine Check / overheating reporting"
1135 select GENERIC_ALLOCATOR
1138 Machine Check support allows the processor to notify the
1139 kernel if it detects a problem (e.g. overheating, data corruption).
1140 The action the kernel takes depends on the severity of the problem,
1141 ranging from warning messages to halting the machine.
1143 config X86_MCELOG_LEGACY
1144 bool "Support for deprecated /dev/mcelog character device"
1147 Enable support for /dev/mcelog which is needed by the old mcelog
1148 userspace logging daemon. Consider switching to the new generation
1151 config X86_MCE_INTEL
1153 prompt "Intel MCE features"
1154 depends on X86_MCE && X86_LOCAL_APIC
1156 Additional support for intel specific MCE features such as
1157 the thermal monitor.
1161 prompt "AMD MCE features"
1162 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1164 Additional support for AMD specific MCE features such as
1165 the DRAM Error Threshold.
1167 config X86_ANCIENT_MCE
1168 bool "Support for old Pentium 5 / WinChip machine checks"
1169 depends on X86_32 && X86_MCE
1171 Include support for machine check handling on old Pentium 5 or WinChip
1172 systems. These typically need to be enabled explicitly on the command
1175 config X86_MCE_THRESHOLD
1176 depends on X86_MCE_AMD || X86_MCE_INTEL
1179 config X86_MCE_INJECT
1180 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1181 tristate "Machine check injector support"
1183 Provide support for injecting machine checks for testing purposes.
1184 If you don't know what a machine check is and you don't do kernel
1185 QA it is safe to say n.
1187 source "arch/x86/events/Kconfig"
1189 config X86_LEGACY_VM86
1190 bool "Legacy VM86 support"
1193 This option allows user programs to put the CPU into V8086
1194 mode, which is an 80286-era approximation of 16-bit real mode.
1196 Some very old versions of X and/or vbetool require this option
1197 for user mode setting. Similarly, DOSEMU will use it if
1198 available to accelerate real mode DOS programs. However, any
1199 recent version of DOSEMU, X, or vbetool should be fully
1200 functional even without kernel VM86 support, as they will all
1201 fall back to software emulation. Nevertheless, if you are using
1202 a 16-bit DOS program where 16-bit performance matters, vm86
1203 mode might be faster than emulation and you might want to
1206 Note that any app that works on a 64-bit kernel is unlikely to
1207 need this option, as 64-bit kernels don't, and can't, support
1208 V8086 mode. This option is also unrelated to 16-bit protected
1209 mode and is not needed to run most 16-bit programs under Wine.
1211 Enabling this option increases the complexity of the kernel
1212 and slows down exception handling a tiny bit.
1214 If unsure, say N here.
1218 default X86_LEGACY_VM86
1221 bool "Enable support for 16-bit segments" if EXPERT
1223 depends on MODIFY_LDT_SYSCALL
1225 This option is required by programs like Wine to run 16-bit
1226 protected mode legacy code on x86 processors. Disabling
1227 this option saves about 300 bytes on i386, or around 6K text
1228 plus 16K runtime memory on x86-64,
1232 depends on X86_16BIT && X86_32
1236 depends on X86_16BIT && X86_64
1238 config X86_VSYSCALL_EMULATION
1239 bool "Enable vsyscall emulation" if EXPERT
1243 This enables emulation of the legacy vsyscall page. Disabling
1244 it is roughly equivalent to booting with vsyscall=none, except
1245 that it will also disable the helpful warning if a program
1246 tries to use a vsyscall. With this option set to N, offending
1247 programs will just segfault, citing addresses of the form
1250 This option is required by many programs built before 2013, and
1251 care should be used even with newer programs if set to N.
1253 Disabling this option saves about 7K of kernel size and
1254 possibly 4K of additional runtime pagetable memory.
1256 config X86_IOPL_IOPERM
1257 bool "IOPERM and IOPL Emulation"
1260 This enables the ioperm() and iopl() syscalls which are necessary
1261 for legacy applications.
1263 Legacy IOPL support is an overbroad mechanism which allows user
1264 space aside of accessing all 65536 I/O ports also to disable
1265 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1266 capabilities and permission from potentially active security
1269 The emulation restricts the functionality of the syscall to
1270 only allowing the full range I/O port access, but prevents the
1271 ability to disable interrupts from user space which would be
1272 granted if the hardware IOPL mechanism would be used.
1275 tristate "Toshiba Laptop support"
1278 This adds a driver to safely access the System Management Mode of
1279 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1280 not work on models with a Phoenix BIOS. The System Management Mode
1281 is used to set the BIOS and power saving options on Toshiba portables.
1283 For information on utilities to make use of this driver see the
1284 Toshiba Linux utilities web site at:
1285 <http://www.buzzard.org.uk/toshiba/>.
1287 Say Y if you intend to run this kernel on a Toshiba portable.
1290 config X86_REBOOTFIXUPS
1291 bool "Enable X86 board specific fixups for reboot"
1294 This enables chipset and/or board specific fixups to be done
1295 in order to get reboot to work correctly. This is only needed on
1296 some combinations of hardware and BIOS. The symptom, for which
1297 this config is intended, is when reboot ends with a stalled/hung
1300 Currently, the only fixup is for the Geode machines using
1301 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1303 Say Y if you want to enable the fixup. Currently, it's safe to
1304 enable this option even if you don't need it.
1308 bool "CPU microcode loading support"
1310 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1312 If you say Y here, you will be able to update the microcode on
1313 Intel and AMD processors. The Intel support is for the IA32 family,
1314 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1315 AMD support is for families 0x10 and later. You will obviously need
1316 the actual microcode binary data itself which is not shipped with
1319 The preferred method to load microcode from a detached initrd is described
1320 in Documentation/x86/microcode.rst. For that you need to enable
1321 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1322 initrd for microcode blobs.
1324 In addition, you can build the microcode into the kernel. For that you
1325 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1328 config MICROCODE_INTEL
1329 bool "Intel microcode loading support"
1330 depends on CPU_SUP_INTEL && MICROCODE
1333 This options enables microcode patch loading support for Intel
1336 For the current Intel microcode data package go to
1337 <https://downloadcenter.intel.com> and search for
1338 'Linux Processor Microcode Data File'.
1340 config MICROCODE_AMD
1341 bool "AMD microcode loading support"
1342 depends on CPU_SUP_AMD && MICROCODE
1344 If you select this option, microcode patch loading support for AMD
1345 processors will be enabled.
1347 config MICROCODE_LATE_LOADING
1348 bool "Late microcode loading (DANGEROUS)"
1350 depends on MICROCODE
1352 Loading microcode late, when the system is up and executing instructions
1353 is a tricky business and should be avoided if possible. Just the sequence
1354 of synchronizing all cores and SMT threads is one fragile dance which does
1355 not guarantee that cores might not softlock after the loading. Therefore,
1356 use this at your own risk. Late loading taints the kernel too.
1359 tristate "/dev/cpu/*/msr - Model-specific register support"
1361 This device gives privileged processes access to the x86
1362 Model-Specific Registers (MSRs). It is a character device with
1363 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1364 MSR accesses are directed to a specific CPU on multi-processor
1368 tristate "/dev/cpu/*/cpuid - CPU information support"
1370 This device gives processes access to the x86 CPUID instruction to
1371 be executed on a specific processor. It is a character device
1372 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1376 prompt "High Memory Support"
1383 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1384 However, the address space of 32-bit x86 processors is only 4
1385 Gigabytes large. That means that, if you have a large amount of
1386 physical memory, not all of it can be "permanently mapped" by the
1387 kernel. The physical memory that's not permanently mapped is called
1390 If you are compiling a kernel which will never run on a machine with
1391 more than 1 Gigabyte total physical RAM, answer "off" here (default
1392 choice and suitable for most users). This will result in a "3GB/1GB"
1393 split: 3GB are mapped so that each process sees a 3GB virtual memory
1394 space and the remaining part of the 4GB virtual memory space is used
1395 by the kernel to permanently map as much physical memory as
1398 If the machine has between 1 and 4 Gigabytes physical RAM, then
1401 If more than 4 Gigabytes is used then answer "64GB" here. This
1402 selection turns Intel PAE (Physical Address Extension) mode on.
1403 PAE implements 3-level paging on IA32 processors. PAE is fully
1404 supported by Linux, PAE mode is implemented on all recent Intel
1405 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1406 then the kernel will not boot on CPUs that don't support PAE!
1408 The actual amount of total physical memory will either be
1409 auto detected or can be forced by using a kernel command line option
1410 such as "mem=256M". (Try "man bootparam" or see the documentation of
1411 your boot loader (lilo or loadlin) about how to pass options to the
1412 kernel at boot time.)
1414 If unsure, say "off".
1419 Select this if you have a 32-bit processor and between 1 and 4
1420 gigabytes of physical RAM.
1424 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1427 Select this if you have a 32-bit processor and more than 4
1428 gigabytes of physical RAM.
1433 prompt "Memory split" if EXPERT
1437 Select the desired split between kernel and user memory.
1439 If the address range available to the kernel is less than the
1440 physical memory installed, the remaining memory will be available
1441 as "high memory". Accessing high memory is a little more costly
1442 than low memory, as it needs to be mapped into the kernel first.
1443 Note that increasing the kernel address space limits the range
1444 available to user programs, making the address space there
1445 tighter. Selecting anything other than the default 3G/1G split
1446 will also likely make your kernel incompatible with binary-only
1449 If you are not absolutely sure what you are doing, leave this
1453 bool "3G/1G user/kernel split"
1454 config VMSPLIT_3G_OPT
1456 bool "3G/1G user/kernel split (for full 1G low memory)"
1458 bool "2G/2G user/kernel split"
1459 config VMSPLIT_2G_OPT
1461 bool "2G/2G user/kernel split (for full 2G low memory)"
1463 bool "1G/3G user/kernel split"
1468 default 0xB0000000 if VMSPLIT_3G_OPT
1469 default 0x80000000 if VMSPLIT_2G
1470 default 0x78000000 if VMSPLIT_2G_OPT
1471 default 0x40000000 if VMSPLIT_1G
1477 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1480 bool "PAE (Physical Address Extension) Support"
1481 depends on X86_32 && !HIGHMEM4G
1482 select PHYS_ADDR_T_64BIT
1485 PAE is required for NX support, and furthermore enables
1486 larger swapspace support for non-overcommit purposes. It
1487 has the cost of more pagetable lookup overhead, and also
1488 consumes more pagetable space per process.
1491 bool "Enable 5-level page tables support"
1493 select DYNAMIC_MEMORY_LAYOUT
1494 select SPARSEMEM_VMEMMAP
1497 5-level paging enables access to larger address space:
1498 upto 128 PiB of virtual address space and 4 PiB of
1499 physical address space.
1501 It will be supported by future Intel CPUs.
1503 A kernel with the option enabled can be booted on machines that
1504 support 4- or 5-level paging.
1506 See Documentation/x86/x86_64/5level-paging.rst for more
1511 config X86_DIRECT_GBPAGES
1515 Certain kernel features effectively disable kernel
1516 linear 1 GB mappings (even if the CPU otherwise
1517 supports them), so don't confuse the user by printing
1518 that we have them enabled.
1520 config X86_CPA_STATISTICS
1521 bool "Enable statistic for Change Page Attribute"
1524 Expose statistics about the Change Page Attribute mechanism, which
1525 helps to determine the effectiveness of preserving large and huge
1526 page mappings when mapping protections are changed.
1528 config X86_MEM_ENCRYPT
1529 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1530 select DYNAMIC_PHYSICAL_MASK
1533 config AMD_MEM_ENCRYPT
1534 bool "AMD Secure Memory Encryption (SME) support"
1535 depends on X86_64 && CPU_SUP_AMD
1536 select DMA_COHERENT_POOL
1537 select ARCH_USE_MEMREMAP_PROT
1538 select INSTRUCTION_DECODER
1539 select ARCH_HAS_CC_PLATFORM
1540 select X86_MEM_ENCRYPT
1542 Say yes to enable support for the encryption of system memory.
1543 This requires an AMD processor that supports Secure Memory
1546 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1547 bool "Activate AMD Secure Memory Encryption (SME) by default"
1548 depends on AMD_MEM_ENCRYPT
1550 Say yes to have system memory encrypted by default if running on
1551 an AMD processor that supports Secure Memory Encryption (SME).
1553 If set to Y, then the encryption of system memory can be
1554 deactivated with the mem_encrypt=off command line option.
1556 If set to N, then the encryption of system memory can be
1557 activated with the mem_encrypt=on command line option.
1559 # Common NUMA Features
1561 bool "NUMA Memory Allocation and Scheduler Support"
1563 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1564 default y if X86_BIGSMP
1565 select USE_PERCPU_NUMA_NODE_ID
1567 Enable NUMA (Non-Uniform Memory Access) support.
1569 The kernel will try to allocate memory used by a CPU on the
1570 local memory controller of the CPU and add some more
1571 NUMA awareness to the kernel.
1573 For 64-bit this is recommended if the system is Intel Core i7
1574 (or later), AMD Opteron, or EM64T NUMA.
1576 For 32-bit this is only needed if you boot a 32-bit
1577 kernel on a 64-bit NUMA platform.
1579 Otherwise, you should say N.
1583 prompt "Old style AMD Opteron NUMA detection"
1584 depends on X86_64 && NUMA && PCI
1586 Enable AMD NUMA node topology detection. You should say Y here if
1587 you have a multi processor AMD system. This uses an old method to
1588 read the NUMA configuration directly from the builtin Northbridge
1589 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1590 which also takes priority if both are compiled in.
1592 config X86_64_ACPI_NUMA
1594 prompt "ACPI NUMA detection"
1595 depends on X86_64 && NUMA && ACPI && PCI
1598 Enable ACPI SRAT based node topology detection.
1601 bool "NUMA emulation"
1604 Enable NUMA emulation. A flat machine will be split
1605 into virtual nodes when booted with "numa=fake=N", where N is the
1606 number of nodes. This is only useful for debugging.
1609 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1611 default "10" if MAXSMP
1612 default "6" if X86_64
1616 Specify the maximum number of NUMA Nodes available on the target
1617 system. Increases memory reserved to accommodate various tables.
1619 config ARCH_FLATMEM_ENABLE
1621 depends on X86_32 && !NUMA
1623 config ARCH_SPARSEMEM_ENABLE
1625 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1626 select SPARSEMEM_STATIC if X86_32
1627 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1629 config ARCH_SPARSEMEM_DEFAULT
1630 def_bool X86_64 || (NUMA && X86_32)
1632 config ARCH_SELECT_MEMORY_MODEL
1634 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1636 config ARCH_MEMORY_PROBE
1637 bool "Enable sysfs memory/probe interface"
1638 depends on MEMORY_HOTPLUG
1640 This option enables a sysfs memory/probe interface for testing.
1641 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1642 If you are unsure how to answer this question, answer N.
1644 config ARCH_PROC_KCORE_TEXT
1646 depends on X86_64 && PROC_KCORE
1648 config ILLEGAL_POINTER_VALUE
1651 default 0xdead000000000000 if X86_64
1653 config X86_PMEM_LEGACY_DEVICE
1656 config X86_PMEM_LEGACY
1657 tristate "Support non-standard NVDIMMs and ADR protected memory"
1658 depends on PHYS_ADDR_T_64BIT
1660 select X86_PMEM_LEGACY_DEVICE
1661 select NUMA_KEEP_MEMINFO if NUMA
1664 Treat memory marked using the non-standard e820 type of 12 as used
1665 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1666 The kernel will offer these regions to the 'pmem' driver so
1667 they can be used for persistent storage.
1672 bool "Allocate 3rd-level pagetables from highmem"
1675 The VM uses one page table entry for each page of physical memory.
1676 For systems with a lot of RAM, this can be wasteful of precious
1677 low memory. Setting this option will put user-space page table
1678 entries in high memory.
1680 config X86_CHECK_BIOS_CORRUPTION
1681 bool "Check for low memory corruption"
1683 Periodically check for memory corruption in low memory, which
1684 is suspected to be caused by BIOS. Even when enabled in the
1685 configuration, it is disabled at runtime. Enable it by
1686 setting "memory_corruption_check=1" on the kernel command
1687 line. By default it scans the low 64k of memory every 60
1688 seconds; see the memory_corruption_check_size and
1689 memory_corruption_check_period parameters in
1690 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1692 When enabled with the default parameters, this option has
1693 almost no overhead, as it reserves a relatively small amount
1694 of memory and scans it infrequently. It both detects corruption
1695 and prevents it from affecting the running system.
1697 It is, however, intended as a diagnostic tool; if repeatable
1698 BIOS-originated corruption always affects the same memory,
1699 you can use memmap= to prevent the kernel from using that
1702 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1703 bool "Set the default setting of memory_corruption_check"
1704 depends on X86_CHECK_BIOS_CORRUPTION
1707 Set whether the default state of memory_corruption_check is
1710 config MATH_EMULATION
1712 depends on MODIFY_LDT_SYSCALL
1713 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1715 Linux can emulate a math coprocessor (used for floating point
1716 operations) if you don't have one. 486DX and Pentium processors have
1717 a math coprocessor built in, 486SX and 386 do not, unless you added
1718 a 487DX or 387, respectively. (The messages during boot time can
1719 give you some hints here ["man dmesg"].) Everyone needs either a
1720 coprocessor or this emulation.
1722 If you don't have a math coprocessor, you need to say Y here; if you
1723 say Y here even though you have a coprocessor, the coprocessor will
1724 be used nevertheless. (This behavior can be changed with the kernel
1725 command line option "no387", which comes handy if your coprocessor
1726 is broken. Try "man bootparam" or see the documentation of your boot
1727 loader (lilo or loadlin) about how to pass options to the kernel at
1728 boot time.) This means that it is a good idea to say Y here if you
1729 intend to use this kernel on different machines.
1731 More information about the internals of the Linux math coprocessor
1732 emulation can be found in <file:arch/x86/math-emu/README>.
1734 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1735 kernel, it won't hurt.
1739 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1741 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1742 the Memory Type Range Registers (MTRRs) may be used to control
1743 processor access to memory ranges. This is most useful if you have
1744 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1745 allows bus write transfers to be combined into a larger transfer
1746 before bursting over the PCI/AGP bus. This can increase performance
1747 of image write operations 2.5 times or more. Saying Y here creates a
1748 /proc/mtrr file which may be used to manipulate your processor's
1749 MTRRs. Typically the X server should use this.
1751 This code has a reasonably generic interface so that similar
1752 control registers on other processors can be easily supported
1755 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1756 Registers (ARRs) which provide a similar functionality to MTRRs. For
1757 these, the ARRs are used to emulate the MTRRs.
1758 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1759 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1760 write-combining. All of these processors are supported by this code
1761 and it makes sense to say Y here if you have one of them.
1763 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1764 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1765 can lead to all sorts of problems, so it's good to say Y here.
1767 You can safely say Y even if your machine doesn't have MTRRs, you'll
1768 just add about 9 KB to your kernel.
1770 See <file:Documentation/x86/mtrr.rst> for more information.
1772 config MTRR_SANITIZER
1774 prompt "MTRR cleanup support"
1777 Convert MTRR layout from continuous to discrete, so X drivers can
1778 add writeback entries.
1780 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1781 The largest mtrr entry size for a continuous block can be set with
1786 config MTRR_SANITIZER_ENABLE_DEFAULT
1787 int "MTRR cleanup enable value (0-1)"
1790 depends on MTRR_SANITIZER
1792 Enable mtrr cleanup default value
1794 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1795 int "MTRR cleanup spare reg num (0-7)"
1798 depends on MTRR_SANITIZER
1800 mtrr cleanup spare entries default, it can be changed via
1801 mtrr_spare_reg_nr=N on the kernel command line.
1805 prompt "x86 PAT support" if EXPERT
1808 Use PAT attributes to setup page level cache control.
1810 PATs are the modern equivalents of MTRRs and are much more
1811 flexible than MTRRs.
1813 Say N here if you see bootup problems (boot crash, boot hang,
1814 spontaneous reboots) or a non-working video driver.
1818 config ARCH_USES_PG_UNCACHED
1824 prompt "User Mode Instruction Prevention" if EXPERT
1826 User Mode Instruction Prevention (UMIP) is a security feature in
1827 some x86 processors. If enabled, a general protection fault is
1828 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1829 executed in user mode. These instructions unnecessarily expose
1830 information about the hardware state.
1832 The vast majority of applications do not use these instructions.
1833 For the very few that do, software emulation is provided in
1834 specific cases in protected and virtual-8086 modes. Emulated
1838 # GCC >= 9 and binutils >= 2.29
1839 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1841 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1842 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1843 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1844 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1847 config X86_KERNEL_IBT
1848 prompt "Indirect Branch Tracking"
1850 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1851 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1852 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1855 Build the kernel with support for Indirect Branch Tracking, a
1856 hardware support course-grain forward-edge Control Flow Integrity
1857 protection. It enforces that all indirect calls must land on
1858 an ENDBR instruction, as such, the compiler will instrument the
1859 code with them to make this happen.
1861 In addition to building the kernel with IBT, seal all functions that
1862 are not indirect call targets, avoiding them ever becoming one.
1864 This requires LTO like objtool runs and will slow down the build. It
1865 does significantly reduce the number of ENDBR instructions in the
1868 config X86_INTEL_MEMORY_PROTECTION_KEYS
1869 prompt "Memory Protection Keys"
1871 # Note: only available in 64-bit mode
1872 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1873 select ARCH_USES_HIGH_VMA_FLAGS
1874 select ARCH_HAS_PKEYS
1876 Memory Protection Keys provides a mechanism for enforcing
1877 page-based protections, but without requiring modification of the
1878 page tables when an application changes protection domains.
1880 For details, see Documentation/core-api/protection-keys.rst
1885 prompt "TSX enable mode"
1886 depends on CPU_SUP_INTEL
1887 default X86_INTEL_TSX_MODE_OFF
1889 Intel's TSX (Transactional Synchronization Extensions) feature
1890 allows to optimize locking protocols through lock elision which
1891 can lead to a noticeable performance boost.
1893 On the other hand it has been shown that TSX can be exploited
1894 to form side channel attacks (e.g. TAA) and chances are there
1895 will be more of those attacks discovered in the future.
1897 Therefore TSX is not enabled by default (aka tsx=off). An admin
1898 might override this decision by tsx=on the command line parameter.
1899 Even with TSX enabled, the kernel will attempt to enable the best
1900 possible TAA mitigation setting depending on the microcode available
1901 for the particular machine.
1903 This option allows to set the default tsx mode between tsx=on, =off
1904 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1907 Say off if not sure, auto if TSX is in use but it should be used on safe
1908 platforms or on if TSX is in use and the security aspect of tsx is not
1911 config X86_INTEL_TSX_MODE_OFF
1914 TSX is disabled if possible - equals to tsx=off command line parameter.
1916 config X86_INTEL_TSX_MODE_ON
1919 TSX is always enabled on TSX capable HW - equals the tsx=on command
1922 config X86_INTEL_TSX_MODE_AUTO
1925 TSX is enabled on TSX capable HW that is believed to be safe against
1926 side channel attacks- equals the tsx=auto command line parameter.
1930 bool "Software Guard eXtensions (SGX)"
1931 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1933 depends on CRYPTO_SHA256=y
1936 select NUMA_KEEP_MEMINFO if NUMA
1939 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1940 that can be used by applications to set aside private regions of code
1941 and data, referred to as enclaves. An enclave's private memory can
1942 only be accessed by code running within the enclave. Accesses from
1943 outside the enclave, including other enclaves, are disallowed by
1949 bool "EFI runtime service support"
1952 select EFI_RUNTIME_WRAPPERS
1953 select ARCH_USE_MEMREMAP_PROT
1955 This enables the kernel to use EFI runtime services that are
1956 available (such as the EFI variable services).
1958 This option is only useful on systems that have EFI firmware.
1959 In addition, you should use the latest ELILO loader available
1960 at <http://elilo.sourceforge.net> in order to take advantage
1961 of EFI runtime services. However, even with this option, the
1962 resultant kernel should continue to boot on existing non-EFI
1966 bool "EFI stub support"
1968 depends on $(cc-option,-mabi=ms) || X86_32
1971 This kernel feature allows a bzImage to be loaded directly
1972 by EFI firmware without the use of a bootloader.
1974 See Documentation/admin-guide/efi-stub.rst for more information.
1977 bool "EFI mixed-mode support"
1978 depends on EFI_STUB && X86_64
1980 Enabling this feature allows a 64-bit kernel to be booted
1981 on a 32-bit firmware, provided that your CPU supports 64-bit
1984 Note that it is not possible to boot a mixed-mode enabled
1985 kernel via the EFI boot stub - a bootloader that supports
1986 the EFI handover protocol must be used.
1990 source "kernel/Kconfig.hz"
1993 bool "kexec system call"
1996 kexec is a system call that implements the ability to shutdown your
1997 current kernel, and to start another kernel. It is like a reboot
1998 but it is independent of the system firmware. And like a reboot
1999 you can start any kernel with it, not just Linux.
2001 The name comes from the similarity to the exec system call.
2003 It is an ongoing process to be certain the hardware in a machine
2004 is properly shutdown, so do not be surprised if this code does not
2005 initially work for you. As of this writing the exact hardware
2006 interface is strongly in flux, so no good recommendation can be
2010 bool "kexec file based system call"
2012 select HAVE_IMA_KEXEC if IMA
2015 depends on CRYPTO_SHA256=y
2017 This is new version of kexec system call. This system call is
2018 file based and takes file descriptors as system call argument
2019 for kernel and initramfs as opposed to list of segments as
2020 accepted by previous system call.
2022 config ARCH_HAS_KEXEC_PURGATORY
2026 bool "Verify kernel signature during kexec_file_load() syscall"
2027 depends on KEXEC_FILE
2030 This option makes the kexec_file_load() syscall check for a valid
2031 signature of the kernel image. The image can still be loaded without
2032 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2033 there's a signature that we can check, then it must be valid.
2035 In addition to this option, you need to enable signature
2036 verification for the corresponding kernel image type being
2037 loaded in order for this to work.
2039 config KEXEC_SIG_FORCE
2040 bool "Require a valid signature in kexec_file_load() syscall"
2041 depends on KEXEC_SIG
2043 This option makes kernel signature verification mandatory for
2044 the kexec_file_load() syscall.
2046 config KEXEC_BZIMAGE_VERIFY_SIG
2047 bool "Enable bzImage signature verification support"
2048 depends on KEXEC_SIG
2049 depends on SIGNED_PE_FILE_VERIFICATION
2050 select SYSTEM_TRUSTED_KEYRING
2052 Enable bzImage signature verification support.
2055 bool "kernel crash dumps"
2056 depends on X86_64 || (X86_32 && HIGHMEM)
2058 Generate crash dump after being started by kexec.
2059 This should be normally only set in special crash dump kernels
2060 which are loaded in the main kernel with kexec-tools into
2061 a specially reserved region and then later executed after
2062 a crash by kdump/kexec. The crash dump kernel must be compiled
2063 to a memory address not used by the main kernel or BIOS using
2064 PHYSICAL_START, or it must be built as a relocatable image
2065 (CONFIG_RELOCATABLE=y).
2066 For more details see Documentation/admin-guide/kdump/kdump.rst
2070 depends on KEXEC && HIBERNATION
2072 Jump between original kernel and kexeced kernel and invoke
2073 code in physical address mode via KEXEC
2075 config PHYSICAL_START
2076 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2079 This gives the physical address where the kernel is loaded.
2081 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2082 bzImage will decompress itself to above physical address and
2083 run from there. Otherwise, bzImage will run from the address where
2084 it has been loaded by the boot loader and will ignore above physical
2087 In normal kdump cases one does not have to set/change this option
2088 as now bzImage can be compiled as a completely relocatable image
2089 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2090 address. This option is mainly useful for the folks who don't want
2091 to use a bzImage for capturing the crash dump and want to use a
2092 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2093 to be specifically compiled to run from a specific memory area
2094 (normally a reserved region) and this option comes handy.
2096 So if you are using bzImage for capturing the crash dump,
2097 leave the value here unchanged to 0x1000000 and set
2098 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2099 for capturing the crash dump change this value to start of
2100 the reserved region. In other words, it can be set based on
2101 the "X" value as specified in the "crashkernel=YM@XM"
2102 command line boot parameter passed to the panic-ed
2103 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2104 for more details about crash dumps.
2106 Usage of bzImage for capturing the crash dump is recommended as
2107 one does not have to build two kernels. Same kernel can be used
2108 as production kernel and capture kernel. Above option should have
2109 gone away after relocatable bzImage support is introduced. But it
2110 is present because there are users out there who continue to use
2111 vmlinux for dump capture. This option should go away down the
2114 Don't change this unless you know what you are doing.
2117 bool "Build a relocatable kernel"
2120 This builds a kernel image that retains relocation information
2121 so it can be loaded someplace besides the default 1MB.
2122 The relocations tend to make the kernel binary about 10% larger,
2123 but are discarded at runtime.
2125 One use is for the kexec on panic case where the recovery kernel
2126 must live at a different physical address than the primary
2129 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2130 it has been loaded at and the compile time physical address
2131 (CONFIG_PHYSICAL_START) is used as the minimum location.
2133 config RANDOMIZE_BASE
2134 bool "Randomize the address of the kernel image (KASLR)"
2135 depends on RELOCATABLE
2138 In support of Kernel Address Space Layout Randomization (KASLR),
2139 this randomizes the physical address at which the kernel image
2140 is decompressed and the virtual address where the kernel
2141 image is mapped, as a security feature that deters exploit
2142 attempts relying on knowledge of the location of kernel
2145 On 64-bit, the kernel physical and virtual addresses are
2146 randomized separately. The physical address will be anywhere
2147 between 16MB and the top of physical memory (up to 64TB). The
2148 virtual address will be randomized from 16MB up to 1GB (9 bits
2149 of entropy). Note that this also reduces the memory space
2150 available to kernel modules from 1.5GB to 1GB.
2152 On 32-bit, the kernel physical and virtual addresses are
2153 randomized together. They will be randomized from 16MB up to
2154 512MB (8 bits of entropy).
2156 Entropy is generated using the RDRAND instruction if it is
2157 supported. If RDTSC is supported, its value is mixed into
2158 the entropy pool as well. If neither RDRAND nor RDTSC are
2159 supported, then entropy is read from the i8254 timer. The
2160 usable entropy is limited by the kernel being built using
2161 2GB addressing, and that PHYSICAL_ALIGN must be at a
2162 minimum of 2MB. As a result, only 10 bits of entropy are
2163 theoretically possible, but the implementations are further
2164 limited due to memory layouts.
2168 # Relocation on x86 needs some additional build support
2169 config X86_NEED_RELOCS
2171 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2173 config PHYSICAL_ALIGN
2174 hex "Alignment value to which kernel should be aligned"
2176 range 0x2000 0x1000000 if X86_32
2177 range 0x200000 0x1000000 if X86_64
2179 This value puts the alignment restrictions on physical address
2180 where kernel is loaded and run from. Kernel is compiled for an
2181 address which meets above alignment restriction.
2183 If bootloader loads the kernel at a non-aligned address and
2184 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2185 address aligned to above value and run from there.
2187 If bootloader loads the kernel at a non-aligned address and
2188 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2189 load address and decompress itself to the address it has been
2190 compiled for and run from there. The address for which kernel is
2191 compiled already meets above alignment restrictions. Hence the
2192 end result is that kernel runs from a physical address meeting
2193 above alignment restrictions.
2195 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2196 this value must be a multiple of 0x200000.
2198 Don't change this unless you know what you are doing.
2200 config DYNAMIC_MEMORY_LAYOUT
2203 This option makes base addresses of vmalloc and vmemmap as well as
2204 __PAGE_OFFSET movable during boot.
2206 config RANDOMIZE_MEMORY
2207 bool "Randomize the kernel memory sections"
2209 depends on RANDOMIZE_BASE
2210 select DYNAMIC_MEMORY_LAYOUT
2211 default RANDOMIZE_BASE
2213 Randomizes the base virtual address of kernel memory sections
2214 (physical memory mapping, vmalloc & vmemmap). This security feature
2215 makes exploits relying on predictable memory locations less reliable.
2217 The order of allocations remains unchanged. Entropy is generated in
2218 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2219 configuration have in average 30,000 different possible virtual
2220 addresses for each memory section.
2224 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2225 hex "Physical memory mapping padding" if EXPERT
2226 depends on RANDOMIZE_MEMORY
2227 default "0xa" if MEMORY_HOTPLUG
2229 range 0x1 0x40 if MEMORY_HOTPLUG
2232 Define the padding in terabytes added to the existing physical
2233 memory size during kernel memory randomization. It is useful
2234 for memory hotplug support but reduces the entropy available for
2235 address randomization.
2237 If unsure, leave at the default value.
2243 config BOOTPARAM_HOTPLUG_CPU0
2244 bool "Set default setting of cpu0_hotpluggable"
2245 depends on HOTPLUG_CPU
2247 Set whether default state of cpu0_hotpluggable is on or off.
2249 Say Y here to enable CPU0 hotplug by default. If this switch
2250 is turned on, there is no need to give cpu0_hotplug kernel
2251 parameter and the CPU0 hotplug feature is enabled by default.
2253 Please note: there are two known CPU0 dependencies if you want
2254 to enable the CPU0 hotplug feature either by this switch or by
2255 cpu0_hotplug kernel parameter.
2257 First, resume from hibernate or suspend always starts from CPU0.
2258 So hibernate and suspend are prevented if CPU0 is offline.
2260 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2261 offline if any interrupt can not migrate out of CPU0. There may
2262 be other CPU0 dependencies.
2264 Please make sure the dependencies are under your control before
2265 you enable this feature.
2267 Say N if you don't want to enable CPU0 hotplug feature by default.
2268 You still can enable the CPU0 hotplug feature at boot by kernel
2269 parameter cpu0_hotplug.
2271 config DEBUG_HOTPLUG_CPU0
2273 prompt "Debug CPU0 hotplug"
2274 depends on HOTPLUG_CPU
2276 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2277 soon as possible and boots up userspace with CPU0 offlined. User
2278 can online CPU0 back after boot time.
2280 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2281 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2282 compilation or giving cpu0_hotplug kernel parameter at boot.
2288 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2289 depends on COMPAT_32
2291 Certain buggy versions of glibc will crash if they are
2292 presented with a 32-bit vDSO that is not mapped at the address
2293 indicated in its segment table.
2295 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2296 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2297 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2298 the only released version with the bug, but OpenSUSE 9
2299 contains a buggy "glibc 2.3.2".
2301 The symptom of the bug is that everything crashes on startup, saying:
2302 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2304 Saying Y here changes the default value of the vdso32 boot
2305 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2306 This works around the glibc bug but hurts performance.
2308 If unsure, say N: if you are compiling your own kernel, you
2309 are unlikely to be using a buggy version of glibc.
2312 prompt "vsyscall table for legacy applications"
2314 default LEGACY_VSYSCALL_XONLY
2316 Legacy user code that does not know how to find the vDSO expects
2317 to be able to issue three syscalls by calling fixed addresses in
2318 kernel space. Since this location is not randomized with ASLR,
2319 it can be used to assist security vulnerability exploitation.
2321 This setting can be changed at boot time via the kernel command
2322 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2323 is deprecated and can only be enabled using the kernel command
2326 On a system with recent enough glibc (2.14 or newer) and no
2327 static binaries, you can say None without a performance penalty
2328 to improve security.
2330 If unsure, select "Emulate execution only".
2332 config LEGACY_VSYSCALL_XONLY
2333 bool "Emulate execution only"
2335 The kernel traps and emulates calls into the fixed vsyscall
2336 address mapping and does not allow reads. This
2337 configuration is recommended when userspace might use the
2338 legacy vsyscall area but support for legacy binary
2339 instrumentation of legacy code is not needed. It mitigates
2340 certain uses of the vsyscall area as an ASLR-bypassing
2343 config LEGACY_VSYSCALL_NONE
2346 There will be no vsyscall mapping at all. This will
2347 eliminate any risk of ASLR bypass due to the vsyscall
2348 fixed address mapping. Attempts to use the vsyscalls
2349 will be reported to dmesg, so that either old or
2350 malicious userspace programs can be identified.
2355 bool "Built-in kernel command line"
2357 Allow for specifying boot arguments to the kernel at
2358 build time. On some systems (e.g. embedded ones), it is
2359 necessary or convenient to provide some or all of the
2360 kernel boot arguments with the kernel itself (that is,
2361 to not rely on the boot loader to provide them.)
2363 To compile command line arguments into the kernel,
2364 set this option to 'Y', then fill in the
2365 boot arguments in CONFIG_CMDLINE.
2367 Systems with fully functional boot loaders (i.e. non-embedded)
2368 should leave this option set to 'N'.
2371 string "Built-in kernel command string"
2372 depends on CMDLINE_BOOL
2375 Enter arguments here that should be compiled into the kernel
2376 image and used at boot time. If the boot loader provides a
2377 command line at boot time, it is appended to this string to
2378 form the full kernel command line, when the system boots.
2380 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2381 change this behavior.
2383 In most cases, the command line (whether built-in or provided
2384 by the boot loader) should specify the device for the root
2387 config CMDLINE_OVERRIDE
2388 bool "Built-in command line overrides boot loader arguments"
2389 depends on CMDLINE_BOOL && CMDLINE != ""
2391 Set this option to 'Y' to have the kernel ignore the boot loader
2392 command line, and use ONLY the built-in command line.
2394 This is used to work around broken boot loaders. This should
2395 be set to 'N' under normal conditions.
2397 config MODIFY_LDT_SYSCALL
2398 bool "Enable the LDT (local descriptor table)" if EXPERT
2401 Linux can allow user programs to install a per-process x86
2402 Local Descriptor Table (LDT) using the modify_ldt(2) system
2403 call. This is required to run 16-bit or segmented code such as
2404 DOSEMU or some Wine programs. It is also used by some very old
2405 threading libraries.
2407 Enabling this feature adds a small amount of overhead to
2408 context switches and increases the low-level kernel attack
2409 surface. Disabling it removes the modify_ldt(2) system call.
2411 Saying 'N' here may make sense for embedded or server kernels.
2413 config STRICT_SIGALTSTACK_SIZE
2414 bool "Enforce strict size checking for sigaltstack"
2415 depends on DYNAMIC_SIGFRAME
2417 For historical reasons MINSIGSTKSZ is a constant which became
2418 already too small with AVX512 support. Add a mechanism to
2419 enforce strict checking of the sigaltstack size against the
2420 real size of the FPU frame. This option enables the check
2421 by default. It can also be controlled via the kernel command
2422 line option 'strict_sas_size' independent of this config
2423 switch. Enabling it might break existing applications which
2424 allocate a too small sigaltstack but 'work' because they
2425 never get a signal delivered.
2427 Say 'N' unless you want to really enforce this check.
2429 source "kernel/livepatch/Kconfig"
2434 def_bool $(cc-option,-mharden-sls=all)
2436 config CC_HAS_RETURN_THUNK
2437 def_bool $(cc-option,-mfunction-return=thunk-extern)
2439 menuconfig SPECULATION_MITIGATIONS
2440 bool "Mitigations for speculative execution vulnerabilities"
2443 Say Y here to enable options which enable mitigations for
2444 speculative execution hardware vulnerabilities.
2446 If you say N, all mitigations will be disabled. You really
2447 should know what you are doing to say so.
2449 if SPECULATION_MITIGATIONS
2451 config PAGE_TABLE_ISOLATION
2452 bool "Remove the kernel mapping in user mode"
2454 depends on (X86_64 || X86_PAE)
2456 This feature reduces the number of hardware side channels by
2457 ensuring that the majority of kernel addresses are not mapped
2460 See Documentation/x86/pti.rst for more details.
2463 bool "Avoid speculative indirect branches in kernel"
2464 select OBJTOOL if HAVE_OBJTOOL
2467 Compile kernel with the retpoline compiler options to guard against
2468 kernel-to-user data leaks by avoiding speculative indirect
2469 branches. Requires a compiler with -mindirect-branch=thunk-extern
2470 support for full protection. The kernel may run slower.
2473 bool "Enable return-thunks"
2474 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2475 select OBJTOOL if HAVE_OBJTOOL
2478 Compile the kernel with the return-thunks compiler option to guard
2479 against kernel-to-user data leaks by avoiding return speculation.
2480 Requires a compiler with -mfunction-return=thunk-extern
2481 support for full protection. The kernel may run slower.
2483 config CPU_UNRET_ENTRY
2484 bool "Enable UNRET on kernel entry"
2485 depends on CPU_SUP_AMD && RETHUNK && X86_64
2488 Compile the kernel with support for the retbleed=unret mitigation.
2490 config CPU_IBPB_ENTRY
2491 bool "Enable IBPB on kernel entry"
2492 depends on CPU_SUP_AMD && X86_64
2495 Compile the kernel with support for the retbleed=ibpb mitigation.
2497 config CPU_IBRS_ENTRY
2498 bool "Enable IBRS on kernel entry"
2499 depends on CPU_SUP_INTEL && X86_64
2502 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2503 This mitigates both spectre_v2 and retbleed at great cost to
2507 bool "Mitigate Straight-Line-Speculation"
2508 depends on CC_HAS_SLS && X86_64
2509 select OBJTOOL if HAVE_OBJTOOL
2512 Compile the kernel with straight-line-speculation options to guard
2513 against straight line speculation. The kernel image might be slightly
2518 config ARCH_HAS_ADD_PAGES
2520 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2522 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2525 menu "Power management and ACPI options"
2527 config ARCH_HIBERNATION_HEADER
2529 depends on HIBERNATION
2531 source "kernel/power/Kconfig"
2533 source "drivers/acpi/Kconfig"
2540 tristate "APM (Advanced Power Management) BIOS support"
2541 depends on X86_32 && PM_SLEEP
2543 APM is a BIOS specification for saving power using several different
2544 techniques. This is mostly useful for battery powered laptops with
2545 APM compliant BIOSes. If you say Y here, the system time will be
2546 reset after a RESUME operation, the /proc/apm device will provide
2547 battery status information, and user-space programs will receive
2548 notification of APM "events" (e.g. battery status change).
2550 If you select "Y" here, you can disable actual use of the APM
2551 BIOS by passing the "apm=off" option to the kernel at boot time.
2553 Note that the APM support is almost completely disabled for
2554 machines with more than one CPU.
2556 In order to use APM, you will need supporting software. For location
2557 and more information, read <file:Documentation/power/apm-acpi.rst>
2558 and the Battery Powered Linux mini-HOWTO, available from
2559 <http://www.tldp.org/docs.html#howto>.
2561 This driver does not spin down disk drives (see the hdparm(8)
2562 manpage ("man 8 hdparm") for that), and it doesn't turn off
2563 VESA-compliant "green" monitors.
2565 This driver does not support the TI 4000M TravelMate and the ACER
2566 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2567 desktop machines also don't have compliant BIOSes, and this driver
2568 may cause those machines to panic during the boot phase.
2570 Generally, if you don't have a battery in your machine, there isn't
2571 much point in using this driver and you should say N. If you get
2572 random kernel OOPSes or reboots that don't seem to be related to
2573 anything, try disabling/enabling this option (or disabling/enabling
2576 Some other things you should try when experiencing seemingly random,
2579 1) make sure that you have enough swap space and that it is
2581 2) pass the "idle=poll" option to the kernel
2582 3) switch on floating point emulation in the kernel and pass
2583 the "no387" option to the kernel
2584 4) pass the "floppy=nodma" option to the kernel
2585 5) pass the "mem=4M" option to the kernel (thereby disabling
2586 all but the first 4 MB of RAM)
2587 6) make sure that the CPU is not over clocked.
2588 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2589 8) disable the cache from your BIOS settings
2590 9) install a fan for the video card or exchange video RAM
2591 10) install a better fan for the CPU
2592 11) exchange RAM chips
2593 12) exchange the motherboard.
2595 To compile this driver as a module, choose M here: the
2596 module will be called apm.
2600 config APM_IGNORE_USER_SUSPEND
2601 bool "Ignore USER SUSPEND"
2603 This option will ignore USER SUSPEND requests. On machines with a
2604 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2605 series notebooks, it is necessary to say Y because of a BIOS bug.
2607 config APM_DO_ENABLE
2608 bool "Enable PM at boot time"
2610 Enable APM features at boot time. From page 36 of the APM BIOS
2611 specification: "When disabled, the APM BIOS does not automatically
2612 power manage devices, enter the Standby State, enter the Suspend
2613 State, or take power saving steps in response to CPU Idle calls."
2614 This driver will make CPU Idle calls when Linux is idle (unless this
2615 feature is turned off -- see "Do CPU IDLE calls", below). This
2616 should always save battery power, but more complicated APM features
2617 will be dependent on your BIOS implementation. You may need to turn
2618 this option off if your computer hangs at boot time when using APM
2619 support, or if it beeps continuously instead of suspending. Turn
2620 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2621 T400CDT. This is off by default since most machines do fine without
2626 bool "Make CPU Idle calls when idle"
2628 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2629 On some machines, this can activate improved power savings, such as
2630 a slowed CPU clock rate, when the machine is idle. These idle calls
2631 are made after the idle loop has run for some length of time (e.g.,
2632 333 mS). On some machines, this will cause a hang at boot time or
2633 whenever the CPU becomes idle. (On machines with more than one CPU,
2634 this option does nothing.)
2636 config APM_DISPLAY_BLANK
2637 bool "Enable console blanking using APM"
2639 Enable console blanking using the APM. Some laptops can use this to
2640 turn off the LCD backlight when the screen blanker of the Linux
2641 virtual console blanks the screen. Note that this is only used by
2642 the virtual console screen blanker, and won't turn off the backlight
2643 when using the X Window system. This also doesn't have anything to
2644 do with your VESA-compliant power-saving monitor. Further, this
2645 option doesn't work for all laptops -- it might not turn off your
2646 backlight at all, or it might print a lot of errors to the console,
2647 especially if you are using gpm.
2649 config APM_ALLOW_INTS
2650 bool "Allow interrupts during APM BIOS calls"
2652 Normally we disable external interrupts while we are making calls to
2653 the APM BIOS as a measure to lessen the effects of a badly behaving
2654 BIOS implementation. The BIOS should reenable interrupts if it
2655 needs to. Unfortunately, some BIOSes do not -- especially those in
2656 many of the newer IBM Thinkpads. If you experience hangs when you
2657 suspend, try setting this to Y. Otherwise, say N.
2661 source "drivers/cpufreq/Kconfig"
2663 source "drivers/cpuidle/Kconfig"
2665 source "drivers/idle/Kconfig"
2669 menu "Bus options (PCI etc.)"
2672 prompt "PCI access mode"
2673 depends on X86_32 && PCI
2676 On PCI systems, the BIOS can be used to detect the PCI devices and
2677 determine their configuration. However, some old PCI motherboards
2678 have BIOS bugs and may crash if this is done. Also, some embedded
2679 PCI-based systems don't have any BIOS at all. Linux can also try to
2680 detect the PCI hardware directly without using the BIOS.
2682 With this option, you can specify how Linux should detect the
2683 PCI devices. If you choose "BIOS", the BIOS will be used,
2684 if you choose "Direct", the BIOS won't be used, and if you
2685 choose "MMConfig", then PCI Express MMCONFIG will be used.
2686 If you choose "Any", the kernel will try MMCONFIG, then the
2687 direct access method and falls back to the BIOS if that doesn't
2688 work. If unsure, go with the default, which is "Any".
2693 config PCI_GOMMCONFIG
2710 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2712 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2715 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2718 bool "Support mmconfig PCI config space access" if X86_64
2720 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2721 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2725 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2729 depends on PCI && XEN
2731 config MMCONF_FAM10H
2733 depends on X86_64 && PCI_MMCONFIG && ACPI
2735 config PCI_CNB20LE_QUIRK
2736 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2739 Read the PCI windows out of the CNB20LE host bridge. This allows
2740 PCI hotplug to work on systems with the CNB20LE chipset which do
2743 There's no public spec for this chipset, and this functionality
2744 is known to be incomplete.
2746 You should say N unless you know you need this.
2749 bool "ISA bus support on modern systems" if EXPERT
2751 Expose ISA bus device drivers and options available for selection and
2752 configuration. Enable this option if your target machine has an ISA
2753 bus. ISA is an older system, displaced by PCI and newer bus
2754 architectures -- if your target machine is modern, it probably does
2755 not have an ISA bus.
2759 # x86_64 have no ISA slots, but can have ISA-style DMA.
2761 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2764 Enables ISA-style DMA support for devices requiring such controllers.
2772 Find out whether you have ISA slots on your motherboard. ISA is the
2773 name of a bus system, i.e. the way the CPU talks to the other stuff
2774 inside your box. Other bus systems are PCI, EISA, MicroChannel
2775 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2776 newer boards don't support it. If you have ISA, say Y, otherwise N.
2779 tristate "NatSemi SCx200 support"
2781 This provides basic support for National Semiconductor's
2782 (now AMD's) Geode processors. The driver probes for the
2783 PCI-IDs of several on-chip devices, so its a good dependency
2784 for other scx200_* drivers.
2786 If compiled as a module, the driver is named scx200.
2788 config SCx200HR_TIMER
2789 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2793 This driver provides a clocksource built upon the on-chip
2794 27MHz high-resolution timer. Its also a workaround for
2795 NSC Geode SC-1100's buggy TSC, which loses time when the
2796 processor goes idle (as is done by the scheduler). The
2797 other workaround is idle=poll boot option.
2800 bool "One Laptop Per Child support"
2808 Add support for detecting the unique features of the OLPC
2812 bool "OLPC XO-1 Power Management"
2813 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2815 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2818 bool "OLPC XO-1 Real Time Clock"
2819 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2821 Add support for the XO-1 real time clock, which can be used as a
2822 programmable wakeup source.
2825 bool "OLPC XO-1 SCI extras"
2826 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2830 Add support for SCI-based features of the OLPC XO-1 laptop:
2831 - EC-driven system wakeups
2835 - AC adapter status updates
2836 - Battery status updates
2838 config OLPC_XO15_SCI
2839 bool "OLPC XO-1.5 SCI extras"
2840 depends on OLPC && ACPI
2843 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2844 - EC-driven system wakeups
2845 - AC adapter status updates
2846 - Battery status updates
2849 bool "PCEngines ALIX System Support (LED setup)"
2852 This option enables system support for the PCEngines ALIX.
2853 At present this just sets up LEDs for GPIO control on
2854 ALIX2/3/6 boards. However, other system specific setup should
2857 Note: You must still enable the drivers for GPIO and LED support
2858 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2860 Note: You have to set alix.force=1 for boards with Award BIOS.
2863 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2866 This option enables system support for the Soekris Engineering net5501.
2869 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2873 This option enables system support for the Traverse Technologies GEOS.
2876 bool "Technologic Systems TS-5500 platform support"
2878 select CHECK_SIGNATURE
2882 This option enables system support for the Technologic Systems TS-5500.
2888 depends on CPU_SUP_AMD && PCI
2892 menu "Binary Emulations"
2894 config IA32_EMULATION
2895 bool "IA32 Emulation"
2897 select ARCH_WANT_OLD_COMPAT_IPC
2899 select COMPAT_OLD_SIGACTION
2901 Include code to run legacy 32-bit programs under a
2902 64-bit kernel. You should likely turn this on, unless you're
2903 100% sure that you don't have any 32-bit programs left.
2906 bool "x32 ABI for 64-bit mode"
2908 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2909 # compressed debug sections to x86_x32 properly:
2910 # https://github.com/ClangBuiltLinux/linux/issues/514
2911 # https://github.com/ClangBuiltLinux/linux/issues/1141
2912 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2914 Include code to run binaries for the x32 native 32-bit ABI
2915 for 64-bit processors. An x32 process gets access to the
2916 full 64-bit register file and wide data path while leaving
2917 pointers at 32 bits for smaller memory footprint.
2921 depends on IA32_EMULATION || X86_32
2923 select OLD_SIGSUSPEND3
2927 depends on IA32_EMULATION || X86_X32_ABI
2929 config COMPAT_FOR_U64_ALIGNMENT
2935 config HAVE_ATOMIC_IOMAP
2939 source "arch/x86/kvm/Kconfig"
2941 source "arch/x86/Kconfig.assembler"