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_LTO_CLANG
111 select ARCH_SUPPORTS_LTO_CLANG_THIN
112 select ARCH_USE_BUILTIN_BSWAP
113 select ARCH_USE_MEMTEST
114 select ARCH_USE_QUEUED_RWLOCKS
115 select ARCH_USE_QUEUED_SPINLOCKS
116 select ARCH_USE_SYM_ANNOTATIONS
117 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
118 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
119 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
120 select ARCH_WANTS_NO_INSTR
121 select ARCH_WANT_GENERAL_HUGETLB
122 select ARCH_WANT_HUGE_PMD_SHARE
123 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
124 select ARCH_WANT_LD_ORPHAN_WARN
125 select ARCH_WANTS_THP_SWAP if X86_64
126 select ARCH_HAS_PARANOID_L1D_FLUSH
127 select BUILDTIME_TABLE_SORT
129 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
130 select CLOCKSOURCE_WATCHDOG
131 select DCACHE_WORD_ACCESS
132 select DYNAMIC_SIGFRAME
133 select EDAC_ATOMIC_SCRUB
135 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
136 select GENERIC_CLOCKEVENTS_MIN_ADJUST
137 select GENERIC_CMOS_UPDATE
138 select GENERIC_CPU_AUTOPROBE
139 select GENERIC_CPU_VULNERABILITIES
140 select GENERIC_EARLY_IOREMAP
143 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
144 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
145 select GENERIC_IRQ_MIGRATION if SMP
146 select GENERIC_IRQ_PROBE
147 select GENERIC_IRQ_RESERVATION_MODE
148 select GENERIC_IRQ_SHOW
149 select GENERIC_PENDING_IRQ if SMP
150 select GENERIC_PTDUMP
151 select GENERIC_SMP_IDLE_THREAD
152 select GENERIC_TIME_VSYSCALL
153 select GENERIC_GETTIMEOFDAY
154 select GENERIC_VDSO_TIME_NS
155 select GUP_GET_PTE_LOW_HIGH if X86_PAE
156 select HARDIRQS_SW_RESEND
157 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
158 select HAVE_ACPI_APEI if ACPI
159 select HAVE_ACPI_APEI_NMI if ACPI
160 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
161 select HAVE_ARCH_AUDITSYSCALL
162 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
163 select HAVE_ARCH_HUGE_VMALLOC if X86_64
164 select HAVE_ARCH_JUMP_LABEL
165 select HAVE_ARCH_JUMP_LABEL_RELATIVE
166 select HAVE_ARCH_KASAN if X86_64
167 select HAVE_ARCH_KASAN_VMALLOC if X86_64
168 select HAVE_ARCH_KFENCE
169 select HAVE_ARCH_KGDB
170 select HAVE_ARCH_MMAP_RND_BITS if MMU
171 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
172 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
173 select HAVE_ARCH_PREL32_RELOCATIONS
174 select HAVE_ARCH_SECCOMP_FILTER
175 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
176 select HAVE_ARCH_STACKLEAK
177 select HAVE_ARCH_TRACEHOOK
178 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
180 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
181 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
182 select HAVE_ARCH_VMAP_STACK if X86_64
183 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
184 select HAVE_ARCH_WITHIN_STACK_FRAMES
185 select HAVE_ASM_MODVERSIONS
186 select HAVE_CMPXCHG_DOUBLE
187 select HAVE_CMPXCHG_LOCAL
188 select HAVE_CONTEXT_TRACKING_USER if X86_64
189 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
190 select HAVE_C_RECORDMCOUNT
191 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
192 select HAVE_BUILDTIME_MCOUNT_SORT
193 select HAVE_DEBUG_KMEMLEAK
194 select HAVE_DMA_CONTIGUOUS
195 select HAVE_DYNAMIC_FTRACE
196 select HAVE_DYNAMIC_FTRACE_WITH_REGS
197 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
198 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
199 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
200 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
202 select HAVE_EFFICIENT_UNALIGNED_ACCESS
204 select HAVE_EXIT_THREAD
206 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
207 select HAVE_FTRACE_MCOUNT_RECORD
208 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
209 select HAVE_FUNCTION_TRACER
210 select HAVE_GCC_PLUGINS
211 select HAVE_HW_BREAKPOINT
212 select HAVE_IOREMAP_PROT
213 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
214 select HAVE_IRQ_TIME_ACCOUNTING
215 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
216 select HAVE_KERNEL_BZIP2
217 select HAVE_KERNEL_GZIP
218 select HAVE_KERNEL_LZ4
219 select HAVE_KERNEL_LZMA
220 select HAVE_KERNEL_LZO
221 select HAVE_KERNEL_XZ
222 select HAVE_KERNEL_ZSTD
224 select HAVE_KPROBES_ON_FTRACE
225 select HAVE_FUNCTION_ERROR_INJECTION
226 select HAVE_KRETPROBES
229 select HAVE_LIVEPATCH if X86_64
230 select HAVE_MIXED_BREAKPOINTS_REGS
231 select HAVE_MOD_ARCH_SPECIFIC
234 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
236 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
237 select HAVE_OBJTOOL if X86_64
238 select HAVE_OPTPROBES
239 select HAVE_PCSPKR_PLATFORM
240 select HAVE_PERF_EVENTS
241 select HAVE_PERF_EVENTS_NMI
242 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
244 select HAVE_PERF_REGS
245 select HAVE_PERF_USER_STACK_DUMP
246 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
247 select MMU_GATHER_MERGE_VMAS
248 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
249 select HAVE_REGS_AND_STACK_ACCESS_API
250 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
251 select HAVE_FUNCTION_ARG_ACCESS_API
252 select HAVE_SETUP_PER_CPU_AREA
253 select HAVE_SOFTIRQ_ON_OWN_STACK
254 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
255 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
256 select HAVE_STATIC_CALL
257 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
258 select HAVE_PREEMPT_DYNAMIC_CALL
260 select HAVE_SYSCALL_TRACEPOINTS
261 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
262 select HAVE_UNSTABLE_SCHED_CLOCK
263 select HAVE_USER_RETURN_NOTIFIER
264 select HAVE_GENERIC_VDSO
265 select HOTPLUG_SMT if SMP
266 select IRQ_FORCED_THREADING
267 select NEED_PER_CPU_EMBED_FIRST_CHUNK
268 select NEED_PER_CPU_PAGE_FIRST_CHUNK
269 select NEED_SG_DMA_LENGTH
270 select PCI_DOMAINS if PCI
271 select PCI_LOCKLESS_CONFIG if PCI
274 select RTC_MC146818_LIB
277 select SYSCTL_EXCEPTION_TRACE
278 select THREAD_INFO_IN_TASK
279 select TRACE_IRQFLAGS_SUPPORT
280 select TRACE_IRQFLAGS_NMI_SUPPORT
281 select USER_STACKTRACE_SUPPORT
282 select HAVE_ARCH_KCSAN if X86_64
283 select X86_FEATURE_NAMES if PROC_FS
284 select PROC_PID_ARCH_STATUS if PROC_FS
285 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
286 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
288 config INSTRUCTION_DECODER
290 depends on KPROBES || PERF_EVENTS || UPROBES
294 default "elf32-i386" if X86_32
295 default "elf64-x86-64" if X86_64
297 config LOCKDEP_SUPPORT
300 config STACKTRACE_SUPPORT
306 config ARCH_MMAP_RND_BITS_MIN
310 config ARCH_MMAP_RND_BITS_MAX
314 config ARCH_MMAP_RND_COMPAT_BITS_MIN
317 config ARCH_MMAP_RND_COMPAT_BITS_MAX
323 config GENERIC_ISA_DMA
325 depends on ISA_DMA_API
330 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
332 config GENERIC_BUG_RELATIVE_POINTERS
335 config ARCH_MAY_HAVE_PC_FDC
337 depends on ISA_DMA_API
339 config GENERIC_CALIBRATE_DELAY
342 config ARCH_HAS_CPU_RELAX
345 config ARCH_HIBERNATION_POSSIBLE
350 default 1024 if X86_64
353 config ARCH_SUSPEND_POSSIBLE
359 config KASAN_SHADOW_OFFSET
362 default 0xdffffc0000000000
364 config HAVE_INTEL_TXT
366 depends on INTEL_IOMMU && ACPI
370 depends on X86_32 && SMP
374 depends on X86_64 && SMP
376 config ARCH_SUPPORTS_UPROBES
379 config FIX_EARLYCON_MEM
382 config DYNAMIC_PHYSICAL_MASK
385 config PGTABLE_LEVELS
387 default 5 if X86_5LEVEL
392 config CC_HAS_SANE_STACKPROTECTOR
394 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
395 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
397 We have to make sure stack protector is unconditionally disabled if
398 the compiler produces broken code or if it does not let us control
399 the segment on 32-bit kernels.
401 menu "Processor type and features"
404 bool "Symmetric multi-processing support"
406 This enables support for systems with more than one CPU. If you have
407 a system with only one CPU, say N. If you have a system with more
410 If you say N here, the kernel will run on uni- and multiprocessor
411 machines, but will use only one CPU of a multiprocessor machine. If
412 you say Y here, the kernel will run on many, but not all,
413 uniprocessor machines. On a uniprocessor machine, the kernel
414 will run faster if you say N here.
416 Note that if you say Y here and choose architecture "586" or
417 "Pentium" under "Processor family", the kernel will not work on 486
418 architectures. Similarly, multiprocessor kernels for the "PPro"
419 architecture may not work on all Pentium based boards.
421 People using multiprocessor machines who say Y here should also say
422 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
423 Management" code will be disabled if you say Y here.
425 See also <file:Documentation/x86/i386/IO-APIC.rst>,
426 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
427 <http://www.tldp.org/docs.html#howto>.
429 If you don't know what to do here, say N.
431 config X86_FEATURE_NAMES
432 bool "Processor feature human-readable names" if EMBEDDED
435 This option compiles in a table of x86 feature bits and corresponding
436 names. This is required to support /proc/cpuinfo and a few kernel
437 messages. You can disable this to save space, at the expense of
438 making those few kernel messages show numeric feature bits instead.
443 bool "Support x2apic"
444 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
446 This enables x2apic support on CPUs that have this feature.
448 This allows 32-bit apic IDs (so it can support very large systems),
449 and accesses the local apic via MSRs not via mmio.
451 If you don't know what to do here, say N.
454 bool "Enable MPS table" if ACPI
456 depends on X86_LOCAL_APIC
458 For old smp systems that do not have proper acpi support. Newer systems
459 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
463 depends on X86_GOLDFISH
465 config X86_CPU_RESCTRL
466 bool "x86 CPU resource control support"
467 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
469 select PROC_CPU_RESCTRL if PROC_FS
471 Enable x86 CPU resource control support.
473 Provide support for the allocation and monitoring of system resources
476 Intel calls this Intel Resource Director Technology
477 (Intel(R) RDT). More information about RDT can be found in the
478 Intel x86 Architecture Software Developer Manual.
480 AMD calls this AMD Platform Quality of Service (AMD QoS).
481 More information about AMD QoS can be found in the AMD64 Technology
482 Platform Quality of Service Extensions manual.
488 bool "Support for big SMP systems with more than 8 CPUs"
491 This option is needed for the systems that have more than 8 CPUs.
493 config X86_EXTENDED_PLATFORM
494 bool "Support for extended (non-PC) x86 platforms"
497 If you disable this option then the kernel will only support
498 standard PC platforms. (which covers the vast majority of
501 If you enable this option then you'll be able to select support
502 for the following (non-PC) 32 bit x86 platforms:
503 Goldfish (Android emulator)
506 SGI 320/540 (Visual Workstation)
507 STA2X11-based (e.g. Northville)
508 Moorestown MID devices
510 If you have one of these systems, or if you want to build a
511 generic distribution kernel, say Y here - otherwise say N.
515 config X86_EXTENDED_PLATFORM
516 bool "Support for extended (non-PC) x86 platforms"
519 If you disable this option then the kernel will only support
520 standard PC platforms. (which covers the vast majority of
523 If you enable this option then you'll be able to select support
524 for the following (non-PC) 64 bit x86 platforms:
529 If you have one of these systems, or if you want to build a
530 generic distribution kernel, say Y here - otherwise say N.
532 # This is an alphabetically sorted list of 64 bit extended platforms
533 # Please maintain the alphabetic order if and when there are additions
535 bool "Numascale NumaChip"
537 depends on X86_EXTENDED_PLATFORM
540 depends on X86_X2APIC
541 depends on PCI_MMCONFIG
543 Adds support for Numascale NumaChip large-SMP systems. Needed to
544 enable more than ~168 cores.
545 If you don't have one of these, you should say N here.
549 select HYPERVISOR_GUEST
551 depends on X86_64 && PCI
552 depends on X86_EXTENDED_PLATFORM
555 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
556 supposed to run on these EM64T-based machines. Only choose this option
557 if you have one of these machines.
560 bool "SGI Ultraviolet"
562 depends on X86_EXTENDED_PLATFORM
565 depends on KEXEC_CORE
566 depends on X86_X2APIC
569 This option is needed in order to support SGI Ultraviolet systems.
570 If you don't have one of these, you should say N here.
572 # Following is an alphabetically sorted list of 32 bit extended platforms
573 # Please maintain the alphabetic order if and when there are additions
576 bool "Goldfish (Virtual Platform)"
577 depends on X86_EXTENDED_PLATFORM
579 Enable support for the Goldfish virtual platform used primarily
580 for Android development. Unless you are building for the Android
581 Goldfish emulator say N here.
584 bool "CE4100 TV platform"
586 depends on PCI_GODIRECT
587 depends on X86_IO_APIC
589 depends on X86_EXTENDED_PLATFORM
590 select X86_REBOOTFIXUPS
592 select OF_EARLY_FLATTREE
594 Select for the Intel CE media processor (CE4100) SOC.
595 This option compiles in support for the CE4100 SOC for settop
596 boxes and media devices.
599 bool "Intel MID platform support"
600 depends on X86_EXTENDED_PLATFORM
601 depends on X86_PLATFORM_DEVICES
603 depends on X86_64 || (PCI_GOANY && X86_32)
604 depends on X86_IO_APIC
609 Select to build a kernel capable of supporting Intel MID (Mobile
610 Internet Device) platform systems which do not have the PCI legacy
611 interfaces. If you are building for a PC class system say N here.
613 Intel MID platforms are based on an Intel processor and chipset which
614 consume less power than most of the x86 derivatives.
616 config X86_INTEL_QUARK
617 bool "Intel Quark platform support"
619 depends on X86_EXTENDED_PLATFORM
620 depends on X86_PLATFORM_DEVICES
624 depends on X86_IO_APIC
629 Select to include support for Quark X1000 SoC.
630 Say Y here if you have a Quark based system such as the Arduino
631 compatible Intel Galileo.
633 config X86_INTEL_LPSS
634 bool "Intel Low Power Subsystem Support"
635 depends on X86 && ACPI && PCI
640 Select to build support for Intel Low Power Subsystem such as
641 found on Intel Lynxpoint PCH. Selecting this option enables
642 things like clock tree (common clock framework) and pincontrol
643 which are needed by the LPSS peripheral drivers.
645 config X86_AMD_PLATFORM_DEVICE
646 bool "AMD ACPI2Platform devices support"
651 Select to interpret AMD specific ACPI device to platform device
652 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
653 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
654 implemented under PINCTRL subsystem.
657 tristate "Intel SoC IOSF Sideband support for SoC platforms"
660 This option enables sideband register access support for Intel SoC
661 platforms. On these platforms the IOSF sideband is used in lieu of
662 MSR's for some register accesses, mostly but not limited to thermal
663 and power. Drivers may query the availability of this device to
664 determine if they need the sideband in order to work on these
665 platforms. The sideband is available on the following SoC products.
666 This list is not meant to be exclusive.
671 You should say Y if you are running a kernel on one of these SoC's.
673 config IOSF_MBI_DEBUG
674 bool "Enable IOSF sideband access through debugfs"
675 depends on IOSF_MBI && DEBUG_FS
677 Select this option to expose the IOSF sideband access registers (MCR,
678 MDR, MCRX) through debugfs to write and read register information from
679 different units on the SoC. This is most useful for obtaining device
680 state information for debug and analysis. As this is a general access
681 mechanism, users of this option would have specific knowledge of the
682 device they want to access.
684 If you don't require the option or are in doubt, say N.
687 bool "RDC R-321x SoC"
689 depends on X86_EXTENDED_PLATFORM
691 select X86_REBOOTFIXUPS
693 This option is needed for RDC R-321x system-on-chip, also known
695 If you don't have one of these chips, you should say N here.
697 config X86_32_NON_STANDARD
698 bool "Support non-standard 32-bit SMP architectures"
699 depends on X86_32 && SMP
700 depends on X86_EXTENDED_PLATFORM
702 This option compiles in the bigsmp and STA2X11 default
703 subarchitectures. It is intended for a generic binary
704 kernel. If you select them all, kernel will probe it one by
705 one and will fallback to default.
707 # Alphabetically sorted list of Non standard 32 bit platforms
709 config X86_SUPPORTS_MEMORY_FAILURE
711 # MCE code calls memory_failure():
713 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
714 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
715 depends on X86_64 || !SPARSEMEM
716 select ARCH_SUPPORTS_MEMORY_FAILURE
719 bool "STA2X11 Companion Chip Support"
720 depends on X86_32_NON_STANDARD && PCI
725 This adds support for boards based on the STA2X11 IO-Hub,
726 a.k.a. "ConneXt". The chip is used in place of the standard
727 PC chipset, so all "standard" peripherals are missing. If this
728 option is selected the kernel will still be able to boot on
729 standard PC machines.
732 tristate "Eurobraille/Iris poweroff module"
735 The Iris machines from EuroBraille do not have APM or ACPI support
736 to shut themselves down properly. A special I/O sequence is
737 needed to do so, which is what this module does at
740 This is only for Iris machines from EuroBraille.
744 config SCHED_OMIT_FRAME_POINTER
746 prompt "Single-depth WCHAN output"
749 Calculate simpler /proc/<PID>/wchan values. If this option
750 is disabled then wchan values will recurse back to the
751 caller function. This provides more accurate wchan values,
752 at the expense of slightly more scheduling overhead.
754 If in doubt, say "Y".
756 menuconfig HYPERVISOR_GUEST
757 bool "Linux guest support"
759 Say Y here to enable options for running Linux under various hyper-
760 visors. This option enables basic hypervisor detection and platform
763 If you say N, all options in this submenu will be skipped and
764 disabled, and Linux guest support won't be built in.
769 bool "Enable paravirtualization code"
770 depends on HAVE_STATIC_CALL
772 This changes the kernel so it can modify itself when it is run
773 under a hypervisor, potentially improving performance significantly
774 over full virtualization. However, when run without a hypervisor
775 the kernel is theoretically slower and slightly larger.
780 config PARAVIRT_DEBUG
781 bool "paravirt-ops debugging"
782 depends on PARAVIRT && DEBUG_KERNEL
784 Enable to debug paravirt_ops internals. Specifically, BUG if
785 a paravirt_op is missing when it is called.
787 config PARAVIRT_SPINLOCKS
788 bool "Paravirtualization layer for spinlocks"
789 depends on PARAVIRT && SMP
791 Paravirtualized spinlocks allow a pvops backend to replace the
792 spinlock implementation with something virtualization-friendly
793 (for example, block the virtual CPU rather than spinning).
795 It has a minimal impact on native kernels and gives a nice performance
796 benefit on paravirtualized KVM / Xen kernels.
798 If you are unsure how to answer this question, answer Y.
800 config X86_HV_CALLBACK_VECTOR
803 source "arch/x86/xen/Kconfig"
806 bool "KVM Guest support (including kvmclock)"
808 select PARAVIRT_CLOCK
809 select ARCH_CPUIDLE_HALTPOLL
810 select X86_HV_CALLBACK_VECTOR
813 This option enables various optimizations for running under the KVM
814 hypervisor. It includes a paravirtualized clock, so that instead
815 of relying on a PIT (or probably other) emulation by the
816 underlying device model, the host provides the guest with
817 timing infrastructure such as time of day, and system time
819 config ARCH_CPUIDLE_HALTPOLL
821 prompt "Disable host haltpoll when loading haltpoll driver"
823 If virtualized under KVM, disable host haltpoll.
826 bool "Support for running PVH guests"
828 This option enables the PVH entry point for guest virtual machines
829 as specified in the x86/HVM direct boot ABI.
831 config PARAVIRT_TIME_ACCOUNTING
832 bool "Paravirtual steal time accounting"
835 Select this option to enable fine granularity task steal time
836 accounting. Time spent executing other tasks in parallel with
837 the current vCPU is discounted from the vCPU power. To account for
838 that, there can be a small performance impact.
840 If in doubt, say N here.
842 config PARAVIRT_CLOCK
845 config JAILHOUSE_GUEST
846 bool "Jailhouse non-root cell support"
847 depends on X86_64 && PCI
850 This option allows to run Linux as guest in a Jailhouse non-root
851 cell. You can leave this option disabled if you only want to start
852 Jailhouse and run Linux afterwards in the root cell.
855 bool "ACRN Guest support"
857 select X86_HV_CALLBACK_VECTOR
859 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
860 a flexible, lightweight reference open-source hypervisor, built with
861 real-time and safety-criticality in mind. It is built for embedded
862 IOT with small footprint and real-time features. More details can be
863 found in https://projectacrn.org/.
865 config INTEL_TDX_GUEST
866 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
867 depends on X86_64 && CPU_SUP_INTEL
868 depends on X86_X2APIC
869 select ARCH_HAS_CC_PLATFORM
870 select X86_MEM_ENCRYPT
873 Support running as a guest under Intel TDX. Without this support,
874 the guest kernel can not boot or run under TDX.
875 TDX includes memory encryption and integrity capabilities
876 which protect the confidentiality and integrity of guest
877 memory contents and CPU state. TDX guests are protected from
878 some attacks from the VMM.
880 endif # HYPERVISOR_GUEST
882 source "arch/x86/Kconfig.cpu"
886 prompt "HPET Timer Support" if X86_32
888 Use the IA-PC HPET (High Precision Event Timer) to manage
889 time in preference to the PIT and RTC, if a HPET is
891 HPET is the next generation timer replacing legacy 8254s.
892 The HPET provides a stable time base on SMP
893 systems, unlike the TSC, but it is more expensive to access,
894 as it is off-chip. The interface used is documented
895 in the HPET spec, revision 1.
897 You can safely choose Y here. However, HPET will only be
898 activated if the platform and the BIOS support this feature.
899 Otherwise the 8254 will be used for timing services.
901 Choose N to continue using the legacy 8254 timer.
903 config HPET_EMULATE_RTC
905 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
907 # Mark as expert because too many people got it wrong.
908 # The code disables itself when not needed.
911 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
912 bool "Enable DMI scanning" if EXPERT
914 Enabled scanning of DMI to identify machine quirks. Say Y
915 here unless you have verified that your setup is not
916 affected by entries in the DMI blacklist. Required by PNP
920 bool "Old AMD GART IOMMU support"
924 depends on X86_64 && PCI && AMD_NB
926 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
927 GART based hardware IOMMUs.
929 The GART supports full DMA access for devices with 32-bit access
930 limitations, on systems with more than 3 GB. This is usually needed
931 for USB, sound, many IDE/SATA chipsets and some other devices.
933 Newer systems typically have a modern AMD IOMMU, supported via
934 the CONFIG_AMD_IOMMU=y config option.
936 In normal configurations this driver is only active when needed:
937 there's more than 3 GB of memory and the system contains a
938 32-bit limited device.
942 config BOOT_VESA_SUPPORT
945 If true, at least one selected framebuffer driver can take advantage
946 of VESA video modes set at an early boot stage via the vga= parameter.
949 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
950 depends on X86_64 && SMP && DEBUG_KERNEL
951 select CPUMASK_OFFSTACK
953 Enable maximum number of CPUS and NUMA Nodes for this architecture.
957 # The maximum number of CPUs supported:
959 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
960 # and which can be configured interactively in the
961 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
963 # The ranges are different on 32-bit and 64-bit kernels, depending on
964 # hardware capabilities and scalability features of the kernel.
966 # ( If MAXSMP is enabled we just use the highest possible value and disable
967 # interactive configuration. )
970 config NR_CPUS_RANGE_BEGIN
972 default NR_CPUS_RANGE_END if MAXSMP
976 config NR_CPUS_RANGE_END
979 default 64 if SMP && X86_BIGSMP
980 default 8 if SMP && !X86_BIGSMP
983 config NR_CPUS_RANGE_END
986 default 8192 if SMP && CPUMASK_OFFSTACK
987 default 512 if SMP && !CPUMASK_OFFSTACK
990 config NR_CPUS_DEFAULT
993 default 32 if X86_BIGSMP
997 config NR_CPUS_DEFAULT
1000 default 8192 if MAXSMP
1005 int "Maximum number of CPUs" if SMP && !MAXSMP
1006 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1007 default NR_CPUS_DEFAULT
1009 This allows you to specify the maximum number of CPUs which this
1010 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1011 supported value is 8192, otherwise the maximum value is 512. The
1012 minimum value which makes sense is 2.
1014 This is purely to save memory: each supported CPU adds about 8KB
1015 to the kernel image.
1017 config SCHED_CLUSTER
1018 bool "Cluster scheduler support"
1022 Cluster scheduler support improves the CPU scheduler's decision
1023 making when dealing with machines that have clusters of CPUs.
1024 Cluster usually means a couple of CPUs which are placed closely
1025 by sharing mid-level caches, last-level cache tags or internal
1033 prompt "Multi-core scheduler support"
1036 Multi-core scheduler support improves the CPU scheduler's decision
1037 making when dealing with multi-core CPU chips at a cost of slightly
1038 increased overhead in some places. If unsure say N here.
1040 config SCHED_MC_PRIO
1041 bool "CPU core priorities scheduler support"
1042 depends on SCHED_MC && CPU_SUP_INTEL
1043 select X86_INTEL_PSTATE
1047 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1048 core ordering determined at manufacturing time, which allows
1049 certain cores to reach higher turbo frequencies (when running
1050 single threaded workloads) than others.
1052 Enabling this kernel feature teaches the scheduler about
1053 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1054 scheduler's CPU selection logic accordingly, so that higher
1055 overall system performance can be achieved.
1057 This feature will have no effect on CPUs without this feature.
1059 If unsure say Y here.
1063 depends on !SMP && X86_LOCAL_APIC
1066 bool "Local APIC support on uniprocessors" if !PCI_MSI
1068 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1070 A local APIC (Advanced Programmable Interrupt Controller) is an
1071 integrated interrupt controller in the CPU. If you have a single-CPU
1072 system which has a processor with a local APIC, you can say Y here to
1073 enable and use it. If you say Y here even though your machine doesn't
1074 have a local APIC, then the kernel will still run with no slowdown at
1075 all. The local APIC supports CPU-generated self-interrupts (timer,
1076 performance counters), and the NMI watchdog which detects hard
1079 config X86_UP_IOAPIC
1080 bool "IO-APIC support on uniprocessors"
1081 depends on X86_UP_APIC
1083 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1084 SMP-capable replacement for PC-style interrupt controllers. Most
1085 SMP systems and many recent uniprocessor systems have one.
1087 If you have a single-CPU system with an IO-APIC, you can say Y here
1088 to use it. If you say Y here even though your machine doesn't have
1089 an IO-APIC, then the kernel will still run with no slowdown at all.
1091 config X86_LOCAL_APIC
1093 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1094 select IRQ_DOMAIN_HIERARCHY
1095 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1099 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1101 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1102 bool "Reroute for broken boot IRQs"
1103 depends on X86_IO_APIC
1105 This option enables a workaround that fixes a source of
1106 spurious interrupts. This is recommended when threaded
1107 interrupt handling is used on systems where the generation of
1108 superfluous "boot interrupts" cannot be disabled.
1110 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1111 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1112 kernel does during interrupt handling). On chipsets where this
1113 boot IRQ generation cannot be disabled, this workaround keeps
1114 the original IRQ line masked so that only the equivalent "boot
1115 IRQ" is delivered to the CPUs. The workaround also tells the
1116 kernel to set up the IRQ handler on the boot IRQ line. In this
1117 way only one interrupt is delivered to the kernel. Otherwise
1118 the spurious second interrupt may cause the kernel to bring
1119 down (vital) interrupt lines.
1121 Only affects "broken" chipsets. Interrupt sharing may be
1122 increased on these systems.
1125 bool "Machine Check / overheating reporting"
1126 select GENERIC_ALLOCATOR
1129 Machine Check support allows the processor to notify the
1130 kernel if it detects a problem (e.g. overheating, data corruption).
1131 The action the kernel takes depends on the severity of the problem,
1132 ranging from warning messages to halting the machine.
1134 config X86_MCELOG_LEGACY
1135 bool "Support for deprecated /dev/mcelog character device"
1138 Enable support for /dev/mcelog which is needed by the old mcelog
1139 userspace logging daemon. Consider switching to the new generation
1142 config X86_MCE_INTEL
1144 prompt "Intel MCE features"
1145 depends on X86_MCE && X86_LOCAL_APIC
1147 Additional support for intel specific MCE features such as
1148 the thermal monitor.
1152 prompt "AMD MCE features"
1153 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1155 Additional support for AMD specific MCE features such as
1156 the DRAM Error Threshold.
1158 config X86_ANCIENT_MCE
1159 bool "Support for old Pentium 5 / WinChip machine checks"
1160 depends on X86_32 && X86_MCE
1162 Include support for machine check handling on old Pentium 5 or WinChip
1163 systems. These typically need to be enabled explicitly on the command
1166 config X86_MCE_THRESHOLD
1167 depends on X86_MCE_AMD || X86_MCE_INTEL
1170 config X86_MCE_INJECT
1171 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1172 tristate "Machine check injector support"
1174 Provide support for injecting machine checks for testing purposes.
1175 If you don't know what a machine check is and you don't do kernel
1176 QA it is safe to say n.
1178 source "arch/x86/events/Kconfig"
1180 config X86_LEGACY_VM86
1181 bool "Legacy VM86 support"
1184 This option allows user programs to put the CPU into V8086
1185 mode, which is an 80286-era approximation of 16-bit real mode.
1187 Some very old versions of X and/or vbetool require this option
1188 for user mode setting. Similarly, DOSEMU will use it if
1189 available to accelerate real mode DOS programs. However, any
1190 recent version of DOSEMU, X, or vbetool should be fully
1191 functional even without kernel VM86 support, as they will all
1192 fall back to software emulation. Nevertheless, if you are using
1193 a 16-bit DOS program where 16-bit performance matters, vm86
1194 mode might be faster than emulation and you might want to
1197 Note that any app that works on a 64-bit kernel is unlikely to
1198 need this option, as 64-bit kernels don't, and can't, support
1199 V8086 mode. This option is also unrelated to 16-bit protected
1200 mode and is not needed to run most 16-bit programs under Wine.
1202 Enabling this option increases the complexity of the kernel
1203 and slows down exception handling a tiny bit.
1205 If unsure, say N here.
1209 default X86_LEGACY_VM86
1212 bool "Enable support for 16-bit segments" if EXPERT
1214 depends on MODIFY_LDT_SYSCALL
1216 This option is required by programs like Wine to run 16-bit
1217 protected mode legacy code on x86 processors. Disabling
1218 this option saves about 300 bytes on i386, or around 6K text
1219 plus 16K runtime memory on x86-64,
1223 depends on X86_16BIT && X86_32
1227 depends on X86_16BIT && X86_64
1229 config X86_VSYSCALL_EMULATION
1230 bool "Enable vsyscall emulation" if EXPERT
1234 This enables emulation of the legacy vsyscall page. Disabling
1235 it is roughly equivalent to booting with vsyscall=none, except
1236 that it will also disable the helpful warning if a program
1237 tries to use a vsyscall. With this option set to N, offending
1238 programs will just segfault, citing addresses of the form
1241 This option is required by many programs built before 2013, and
1242 care should be used even with newer programs if set to N.
1244 Disabling this option saves about 7K of kernel size and
1245 possibly 4K of additional runtime pagetable memory.
1247 config X86_IOPL_IOPERM
1248 bool "IOPERM and IOPL Emulation"
1251 This enables the ioperm() and iopl() syscalls which are necessary
1252 for legacy applications.
1254 Legacy IOPL support is an overbroad mechanism which allows user
1255 space aside of accessing all 65536 I/O ports also to disable
1256 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1257 capabilities and permission from potentially active security
1260 The emulation restricts the functionality of the syscall to
1261 only allowing the full range I/O port access, but prevents the
1262 ability to disable interrupts from user space which would be
1263 granted if the hardware IOPL mechanism would be used.
1266 tristate "Toshiba Laptop support"
1269 This adds a driver to safely access the System Management Mode of
1270 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1271 not work on models with a Phoenix BIOS. The System Management Mode
1272 is used to set the BIOS and power saving options on Toshiba portables.
1274 For information on utilities to make use of this driver see the
1275 Toshiba Linux utilities web site at:
1276 <http://www.buzzard.org.uk/toshiba/>.
1278 Say Y if you intend to run this kernel on a Toshiba portable.
1281 config X86_REBOOTFIXUPS
1282 bool "Enable X86 board specific fixups for reboot"
1285 This enables chipset and/or board specific fixups to be done
1286 in order to get reboot to work correctly. This is only needed on
1287 some combinations of hardware and BIOS. The symptom, for which
1288 this config is intended, is when reboot ends with a stalled/hung
1291 Currently, the only fixup is for the Geode machines using
1292 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1294 Say Y if you want to enable the fixup. Currently, it's safe to
1295 enable this option even if you don't need it.
1299 bool "CPU microcode loading support"
1301 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1303 If you say Y here, you will be able to update the microcode on
1304 Intel and AMD processors. The Intel support is for the IA32 family,
1305 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1306 AMD support is for families 0x10 and later. You will obviously need
1307 the actual microcode binary data itself which is not shipped with
1310 The preferred method to load microcode from a detached initrd is described
1311 in Documentation/x86/microcode.rst. For that you need to enable
1312 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1313 initrd for microcode blobs.
1315 In addition, you can build the microcode into the kernel. For that you
1316 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1319 config MICROCODE_INTEL
1320 bool "Intel microcode loading support"
1321 depends on CPU_SUP_INTEL && MICROCODE
1324 This options enables microcode patch loading support for Intel
1327 For the current Intel microcode data package go to
1328 <https://downloadcenter.intel.com> and search for
1329 'Linux Processor Microcode Data File'.
1331 config MICROCODE_AMD
1332 bool "AMD microcode loading support"
1333 depends on CPU_SUP_AMD && MICROCODE
1335 If you select this option, microcode patch loading support for AMD
1336 processors will be enabled.
1338 config MICROCODE_LATE_LOADING
1339 bool "Late microcode loading (DANGEROUS)"
1341 depends on MICROCODE
1343 Loading microcode late, when the system is up and executing instructions
1344 is a tricky business and should be avoided if possible. Just the sequence
1345 of synchronizing all cores and SMT threads is one fragile dance which does
1346 not guarantee that cores might not softlock after the loading. Therefore,
1347 use this at your own risk. Late loading taints the kernel too.
1350 tristate "/dev/cpu/*/msr - Model-specific register support"
1352 This device gives privileged processes access to the x86
1353 Model-Specific Registers (MSRs). It is a character device with
1354 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1355 MSR accesses are directed to a specific CPU on multi-processor
1359 tristate "/dev/cpu/*/cpuid - CPU information support"
1361 This device gives processes access to the x86 CPUID instruction to
1362 be executed on a specific processor. It is a character device
1363 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1367 prompt "High Memory Support"
1374 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1375 However, the address space of 32-bit x86 processors is only 4
1376 Gigabytes large. That means that, if you have a large amount of
1377 physical memory, not all of it can be "permanently mapped" by the
1378 kernel. The physical memory that's not permanently mapped is called
1381 If you are compiling a kernel which will never run on a machine with
1382 more than 1 Gigabyte total physical RAM, answer "off" here (default
1383 choice and suitable for most users). This will result in a "3GB/1GB"
1384 split: 3GB are mapped so that each process sees a 3GB virtual memory
1385 space and the remaining part of the 4GB virtual memory space is used
1386 by the kernel to permanently map as much physical memory as
1389 If the machine has between 1 and 4 Gigabytes physical RAM, then
1392 If more than 4 Gigabytes is used then answer "64GB" here. This
1393 selection turns Intel PAE (Physical Address Extension) mode on.
1394 PAE implements 3-level paging on IA32 processors. PAE is fully
1395 supported by Linux, PAE mode is implemented on all recent Intel
1396 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1397 then the kernel will not boot on CPUs that don't support PAE!
1399 The actual amount of total physical memory will either be
1400 auto detected or can be forced by using a kernel command line option
1401 such as "mem=256M". (Try "man bootparam" or see the documentation of
1402 your boot loader (lilo or loadlin) about how to pass options to the
1403 kernel at boot time.)
1405 If unsure, say "off".
1410 Select this if you have a 32-bit processor and between 1 and 4
1411 gigabytes of physical RAM.
1415 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1418 Select this if you have a 32-bit processor and more than 4
1419 gigabytes of physical RAM.
1424 prompt "Memory split" if EXPERT
1428 Select the desired split between kernel and user memory.
1430 If the address range available to the kernel is less than the
1431 physical memory installed, the remaining memory will be available
1432 as "high memory". Accessing high memory is a little more costly
1433 than low memory, as it needs to be mapped into the kernel first.
1434 Note that increasing the kernel address space limits the range
1435 available to user programs, making the address space there
1436 tighter. Selecting anything other than the default 3G/1G split
1437 will also likely make your kernel incompatible with binary-only
1440 If you are not absolutely sure what you are doing, leave this
1444 bool "3G/1G user/kernel split"
1445 config VMSPLIT_3G_OPT
1447 bool "3G/1G user/kernel split (for full 1G low memory)"
1449 bool "2G/2G user/kernel split"
1450 config VMSPLIT_2G_OPT
1452 bool "2G/2G user/kernel split (for full 2G low memory)"
1454 bool "1G/3G user/kernel split"
1459 default 0xB0000000 if VMSPLIT_3G_OPT
1460 default 0x80000000 if VMSPLIT_2G
1461 default 0x78000000 if VMSPLIT_2G_OPT
1462 default 0x40000000 if VMSPLIT_1G
1468 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1471 bool "PAE (Physical Address Extension) Support"
1472 depends on X86_32 && !HIGHMEM4G
1473 select PHYS_ADDR_T_64BIT
1476 PAE is required for NX support, and furthermore enables
1477 larger swapspace support for non-overcommit purposes. It
1478 has the cost of more pagetable lookup overhead, and also
1479 consumes more pagetable space per process.
1482 bool "Enable 5-level page tables support"
1484 select DYNAMIC_MEMORY_LAYOUT
1485 select SPARSEMEM_VMEMMAP
1488 5-level paging enables access to larger address space:
1489 upto 128 PiB of virtual address space and 4 PiB of
1490 physical address space.
1492 It will be supported by future Intel CPUs.
1494 A kernel with the option enabled can be booted on machines that
1495 support 4- or 5-level paging.
1497 See Documentation/x86/x86_64/5level-paging.rst for more
1502 config X86_DIRECT_GBPAGES
1506 Certain kernel features effectively disable kernel
1507 linear 1 GB mappings (even if the CPU otherwise
1508 supports them), so don't confuse the user by printing
1509 that we have them enabled.
1511 config X86_CPA_STATISTICS
1512 bool "Enable statistic for Change Page Attribute"
1515 Expose statistics about the Change Page Attribute mechanism, which
1516 helps to determine the effectiveness of preserving large and huge
1517 page mappings when mapping protections are changed.
1519 config X86_MEM_ENCRYPT
1520 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1521 select DYNAMIC_PHYSICAL_MASK
1524 config AMD_MEM_ENCRYPT
1525 bool "AMD Secure Memory Encryption (SME) support"
1526 depends on X86_64 && CPU_SUP_AMD
1527 select DMA_COHERENT_POOL
1528 select ARCH_USE_MEMREMAP_PROT
1529 select INSTRUCTION_DECODER
1530 select ARCH_HAS_CC_PLATFORM
1531 select X86_MEM_ENCRYPT
1533 Say yes to enable support for the encryption of system memory.
1534 This requires an AMD processor that supports Secure Memory
1537 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1538 bool "Activate AMD Secure Memory Encryption (SME) by default"
1539 depends on AMD_MEM_ENCRYPT
1541 Say yes to have system memory encrypted by default if running on
1542 an AMD processor that supports Secure Memory Encryption (SME).
1544 If set to Y, then the encryption of system memory can be
1545 deactivated with the mem_encrypt=off command line option.
1547 If set to N, then the encryption of system memory can be
1548 activated with the mem_encrypt=on command line option.
1550 # Common NUMA Features
1552 bool "NUMA Memory Allocation and Scheduler Support"
1554 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1555 default y if X86_BIGSMP
1556 select USE_PERCPU_NUMA_NODE_ID
1558 Enable NUMA (Non-Uniform Memory Access) support.
1560 The kernel will try to allocate memory used by a CPU on the
1561 local memory controller of the CPU and add some more
1562 NUMA awareness to the kernel.
1564 For 64-bit this is recommended if the system is Intel Core i7
1565 (or later), AMD Opteron, or EM64T NUMA.
1567 For 32-bit this is only needed if you boot a 32-bit
1568 kernel on a 64-bit NUMA platform.
1570 Otherwise, you should say N.
1574 prompt "Old style AMD Opteron NUMA detection"
1575 depends on X86_64 && NUMA && PCI
1577 Enable AMD NUMA node topology detection. You should say Y here if
1578 you have a multi processor AMD system. This uses an old method to
1579 read the NUMA configuration directly from the builtin Northbridge
1580 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1581 which also takes priority if both are compiled in.
1583 config X86_64_ACPI_NUMA
1585 prompt "ACPI NUMA detection"
1586 depends on X86_64 && NUMA && ACPI && PCI
1589 Enable ACPI SRAT based node topology detection.
1592 bool "NUMA emulation"
1595 Enable NUMA emulation. A flat machine will be split
1596 into virtual nodes when booted with "numa=fake=N", where N is the
1597 number of nodes. This is only useful for debugging.
1600 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1602 default "10" if MAXSMP
1603 default "6" if X86_64
1607 Specify the maximum number of NUMA Nodes available on the target
1608 system. Increases memory reserved to accommodate various tables.
1610 config ARCH_FLATMEM_ENABLE
1612 depends on X86_32 && !NUMA
1614 config ARCH_SPARSEMEM_ENABLE
1616 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1617 select SPARSEMEM_STATIC if X86_32
1618 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1620 config ARCH_SPARSEMEM_DEFAULT
1621 def_bool X86_64 || (NUMA && X86_32)
1623 config ARCH_SELECT_MEMORY_MODEL
1625 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1627 config ARCH_MEMORY_PROBE
1628 bool "Enable sysfs memory/probe interface"
1629 depends on MEMORY_HOTPLUG
1631 This option enables a sysfs memory/probe interface for testing.
1632 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1633 If you are unsure how to answer this question, answer N.
1635 config ARCH_PROC_KCORE_TEXT
1637 depends on X86_64 && PROC_KCORE
1639 config ILLEGAL_POINTER_VALUE
1642 default 0xdead000000000000 if X86_64
1644 config X86_PMEM_LEGACY_DEVICE
1647 config X86_PMEM_LEGACY
1648 tristate "Support non-standard NVDIMMs and ADR protected memory"
1649 depends on PHYS_ADDR_T_64BIT
1651 select X86_PMEM_LEGACY_DEVICE
1652 select NUMA_KEEP_MEMINFO if NUMA
1655 Treat memory marked using the non-standard e820 type of 12 as used
1656 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1657 The kernel will offer these regions to the 'pmem' driver so
1658 they can be used for persistent storage.
1663 bool "Allocate 3rd-level pagetables from highmem"
1666 The VM uses one page table entry for each page of physical memory.
1667 For systems with a lot of RAM, this can be wasteful of precious
1668 low memory. Setting this option will put user-space page table
1669 entries in high memory.
1671 config X86_CHECK_BIOS_CORRUPTION
1672 bool "Check for low memory corruption"
1674 Periodically check for memory corruption in low memory, which
1675 is suspected to be caused by BIOS. Even when enabled in the
1676 configuration, it is disabled at runtime. Enable it by
1677 setting "memory_corruption_check=1" on the kernel command
1678 line. By default it scans the low 64k of memory every 60
1679 seconds; see the memory_corruption_check_size and
1680 memory_corruption_check_period parameters in
1681 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1683 When enabled with the default parameters, this option has
1684 almost no overhead, as it reserves a relatively small amount
1685 of memory and scans it infrequently. It both detects corruption
1686 and prevents it from affecting the running system.
1688 It is, however, intended as a diagnostic tool; if repeatable
1689 BIOS-originated corruption always affects the same memory,
1690 you can use memmap= to prevent the kernel from using that
1693 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1694 bool "Set the default setting of memory_corruption_check"
1695 depends on X86_CHECK_BIOS_CORRUPTION
1698 Set whether the default state of memory_corruption_check is
1701 config MATH_EMULATION
1703 depends on MODIFY_LDT_SYSCALL
1704 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1706 Linux can emulate a math coprocessor (used for floating point
1707 operations) if you don't have one. 486DX and Pentium processors have
1708 a math coprocessor built in, 486SX and 386 do not, unless you added
1709 a 487DX or 387, respectively. (The messages during boot time can
1710 give you some hints here ["man dmesg"].) Everyone needs either a
1711 coprocessor or this emulation.
1713 If you don't have a math coprocessor, you need to say Y here; if you
1714 say Y here even though you have a coprocessor, the coprocessor will
1715 be used nevertheless. (This behavior can be changed with the kernel
1716 command line option "no387", which comes handy if your coprocessor
1717 is broken. Try "man bootparam" or see the documentation of your boot
1718 loader (lilo or loadlin) about how to pass options to the kernel at
1719 boot time.) This means that it is a good idea to say Y here if you
1720 intend to use this kernel on different machines.
1722 More information about the internals of the Linux math coprocessor
1723 emulation can be found in <file:arch/x86/math-emu/README>.
1725 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1726 kernel, it won't hurt.
1730 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1732 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1733 the Memory Type Range Registers (MTRRs) may be used to control
1734 processor access to memory ranges. This is most useful if you have
1735 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1736 allows bus write transfers to be combined into a larger transfer
1737 before bursting over the PCI/AGP bus. This can increase performance
1738 of image write operations 2.5 times or more. Saying Y here creates a
1739 /proc/mtrr file which may be used to manipulate your processor's
1740 MTRRs. Typically the X server should use this.
1742 This code has a reasonably generic interface so that similar
1743 control registers on other processors can be easily supported
1746 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1747 Registers (ARRs) which provide a similar functionality to MTRRs. For
1748 these, the ARRs are used to emulate the MTRRs.
1749 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1750 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1751 write-combining. All of these processors are supported by this code
1752 and it makes sense to say Y here if you have one of them.
1754 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1755 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1756 can lead to all sorts of problems, so it's good to say Y here.
1758 You can safely say Y even if your machine doesn't have MTRRs, you'll
1759 just add about 9 KB to your kernel.
1761 See <file:Documentation/x86/mtrr.rst> for more information.
1763 config MTRR_SANITIZER
1765 prompt "MTRR cleanup support"
1768 Convert MTRR layout from continuous to discrete, so X drivers can
1769 add writeback entries.
1771 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1772 The largest mtrr entry size for a continuous block can be set with
1777 config MTRR_SANITIZER_ENABLE_DEFAULT
1778 int "MTRR cleanup enable value (0-1)"
1781 depends on MTRR_SANITIZER
1783 Enable mtrr cleanup default value
1785 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1786 int "MTRR cleanup spare reg num (0-7)"
1789 depends on MTRR_SANITIZER
1791 mtrr cleanup spare entries default, it can be changed via
1792 mtrr_spare_reg_nr=N on the kernel command line.
1796 prompt "x86 PAT support" if EXPERT
1799 Use PAT attributes to setup page level cache control.
1801 PATs are the modern equivalents of MTRRs and are much more
1802 flexible than MTRRs.
1804 Say N here if you see bootup problems (boot crash, boot hang,
1805 spontaneous reboots) or a non-working video driver.
1809 config ARCH_USES_PG_UNCACHED
1815 prompt "User Mode Instruction Prevention" if EXPERT
1817 User Mode Instruction Prevention (UMIP) is a security feature in
1818 some x86 processors. If enabled, a general protection fault is
1819 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1820 executed in user mode. These instructions unnecessarily expose
1821 information about the hardware state.
1823 The vast majority of applications do not use these instructions.
1824 For the very few that do, software emulation is provided in
1825 specific cases in protected and virtual-8086 modes. Emulated
1829 # GCC >= 9 and binutils >= 2.29
1830 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1832 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1833 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1834 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1835 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1838 config X86_KERNEL_IBT
1839 prompt "Indirect Branch Tracking"
1841 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1842 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1843 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1846 Build the kernel with support for Indirect Branch Tracking, a
1847 hardware support course-grain forward-edge Control Flow Integrity
1848 protection. It enforces that all indirect calls must land on
1849 an ENDBR instruction, as such, the compiler will instrument the
1850 code with them to make this happen.
1852 In addition to building the kernel with IBT, seal all functions that
1853 are not indirect call targets, avoiding them ever becoming one.
1855 This requires LTO like objtool runs and will slow down the build. It
1856 does significantly reduce the number of ENDBR instructions in the
1859 config X86_INTEL_MEMORY_PROTECTION_KEYS
1860 prompt "Memory Protection Keys"
1862 # Note: only available in 64-bit mode
1863 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1864 select ARCH_USES_HIGH_VMA_FLAGS
1865 select ARCH_HAS_PKEYS
1867 Memory Protection Keys provides a mechanism for enforcing
1868 page-based protections, but without requiring modification of the
1869 page tables when an application changes protection domains.
1871 For details, see Documentation/core-api/protection-keys.rst
1876 prompt "TSX enable mode"
1877 depends on CPU_SUP_INTEL
1878 default X86_INTEL_TSX_MODE_OFF
1880 Intel's TSX (Transactional Synchronization Extensions) feature
1881 allows to optimize locking protocols through lock elision which
1882 can lead to a noticeable performance boost.
1884 On the other hand it has been shown that TSX can be exploited
1885 to form side channel attacks (e.g. TAA) and chances are there
1886 will be more of those attacks discovered in the future.
1888 Therefore TSX is not enabled by default (aka tsx=off). An admin
1889 might override this decision by tsx=on the command line parameter.
1890 Even with TSX enabled, the kernel will attempt to enable the best
1891 possible TAA mitigation setting depending on the microcode available
1892 for the particular machine.
1894 This option allows to set the default tsx mode between tsx=on, =off
1895 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1898 Say off if not sure, auto if TSX is in use but it should be used on safe
1899 platforms or on if TSX is in use and the security aspect of tsx is not
1902 config X86_INTEL_TSX_MODE_OFF
1905 TSX is disabled if possible - equals to tsx=off command line parameter.
1907 config X86_INTEL_TSX_MODE_ON
1910 TSX is always enabled on TSX capable HW - equals the tsx=on command
1913 config X86_INTEL_TSX_MODE_AUTO
1916 TSX is enabled on TSX capable HW that is believed to be safe against
1917 side channel attacks- equals the tsx=auto command line parameter.
1921 bool "Software Guard eXtensions (SGX)"
1922 depends on X86_64 && CPU_SUP_INTEL
1924 depends on CRYPTO_SHA256=y
1927 select NUMA_KEEP_MEMINFO if NUMA
1930 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1931 that can be used by applications to set aside private regions of code
1932 and data, referred to as enclaves. An enclave's private memory can
1933 only be accessed by code running within the enclave. Accesses from
1934 outside the enclave, including other enclaves, are disallowed by
1940 bool "EFI runtime service support"
1943 select EFI_RUNTIME_WRAPPERS
1944 select ARCH_USE_MEMREMAP_PROT
1946 This enables the kernel to use EFI runtime services that are
1947 available (such as the EFI variable services).
1949 This option is only useful on systems that have EFI firmware.
1950 In addition, you should use the latest ELILO loader available
1951 at <http://elilo.sourceforge.net> in order to take advantage
1952 of EFI runtime services. However, even with this option, the
1953 resultant kernel should continue to boot on existing non-EFI
1957 bool "EFI stub support"
1959 depends on $(cc-option,-mabi=ms) || X86_32
1962 This kernel feature allows a bzImage to be loaded directly
1963 by EFI firmware without the use of a bootloader.
1965 See Documentation/admin-guide/efi-stub.rst for more information.
1968 bool "EFI mixed-mode support"
1969 depends on EFI_STUB && X86_64
1971 Enabling this feature allows a 64-bit kernel to be booted
1972 on a 32-bit firmware, provided that your CPU supports 64-bit
1975 Note that it is not possible to boot a mixed-mode enabled
1976 kernel via the EFI boot stub - a bootloader that supports
1977 the EFI handover protocol must be used.
1981 source "kernel/Kconfig.hz"
1984 bool "kexec system call"
1987 kexec is a system call that implements the ability to shutdown your
1988 current kernel, and to start another kernel. It is like a reboot
1989 but it is independent of the system firmware. And like a reboot
1990 you can start any kernel with it, not just Linux.
1992 The name comes from the similarity to the exec system call.
1994 It is an ongoing process to be certain the hardware in a machine
1995 is properly shutdown, so do not be surprised if this code does not
1996 initially work for you. As of this writing the exact hardware
1997 interface is strongly in flux, so no good recommendation can be
2001 bool "kexec file based system call"
2003 select HAVE_IMA_KEXEC if IMA
2006 depends on CRYPTO_SHA256=y
2008 This is new version of kexec system call. This system call is
2009 file based and takes file descriptors as system call argument
2010 for kernel and initramfs as opposed to list of segments as
2011 accepted by previous system call.
2013 config ARCH_HAS_KEXEC_PURGATORY
2017 bool "Verify kernel signature during kexec_file_load() syscall"
2018 depends on KEXEC_FILE
2021 This option makes the kexec_file_load() syscall check for a valid
2022 signature of the kernel image. The image can still be loaded without
2023 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2024 there's a signature that we can check, then it must be valid.
2026 In addition to this option, you need to enable signature
2027 verification for the corresponding kernel image type being
2028 loaded in order for this to work.
2030 config KEXEC_SIG_FORCE
2031 bool "Require a valid signature in kexec_file_load() syscall"
2032 depends on KEXEC_SIG
2034 This option makes kernel signature verification mandatory for
2035 the kexec_file_load() syscall.
2037 config KEXEC_BZIMAGE_VERIFY_SIG
2038 bool "Enable bzImage signature verification support"
2039 depends on KEXEC_SIG
2040 depends on SIGNED_PE_FILE_VERIFICATION
2041 select SYSTEM_TRUSTED_KEYRING
2043 Enable bzImage signature verification support.
2046 bool "kernel crash dumps"
2047 depends on X86_64 || (X86_32 && HIGHMEM)
2049 Generate crash dump after being started by kexec.
2050 This should be normally only set in special crash dump kernels
2051 which are loaded in the main kernel with kexec-tools into
2052 a specially reserved region and then later executed after
2053 a crash by kdump/kexec. The crash dump kernel must be compiled
2054 to a memory address not used by the main kernel or BIOS using
2055 PHYSICAL_START, or it must be built as a relocatable image
2056 (CONFIG_RELOCATABLE=y).
2057 For more details see Documentation/admin-guide/kdump/kdump.rst
2061 depends on KEXEC && HIBERNATION
2063 Jump between original kernel and kexeced kernel and invoke
2064 code in physical address mode via KEXEC
2066 config PHYSICAL_START
2067 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2070 This gives the physical address where the kernel is loaded.
2072 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2073 bzImage will decompress itself to above physical address and
2074 run from there. Otherwise, bzImage will run from the address where
2075 it has been loaded by the boot loader and will ignore above physical
2078 In normal kdump cases one does not have to set/change this option
2079 as now bzImage can be compiled as a completely relocatable image
2080 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2081 address. This option is mainly useful for the folks who don't want
2082 to use a bzImage for capturing the crash dump and want to use a
2083 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2084 to be specifically compiled to run from a specific memory area
2085 (normally a reserved region) and this option comes handy.
2087 So if you are using bzImage for capturing the crash dump,
2088 leave the value here unchanged to 0x1000000 and set
2089 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2090 for capturing the crash dump change this value to start of
2091 the reserved region. In other words, it can be set based on
2092 the "X" value as specified in the "crashkernel=YM@XM"
2093 command line boot parameter passed to the panic-ed
2094 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2095 for more details about crash dumps.
2097 Usage of bzImage for capturing the crash dump is recommended as
2098 one does not have to build two kernels. Same kernel can be used
2099 as production kernel and capture kernel. Above option should have
2100 gone away after relocatable bzImage support is introduced. But it
2101 is present because there are users out there who continue to use
2102 vmlinux for dump capture. This option should go away down the
2105 Don't change this unless you know what you are doing.
2108 bool "Build a relocatable kernel"
2111 This builds a kernel image that retains relocation information
2112 so it can be loaded someplace besides the default 1MB.
2113 The relocations tend to make the kernel binary about 10% larger,
2114 but are discarded at runtime.
2116 One use is for the kexec on panic case where the recovery kernel
2117 must live at a different physical address than the primary
2120 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2121 it has been loaded at and the compile time physical address
2122 (CONFIG_PHYSICAL_START) is used as the minimum location.
2124 config RANDOMIZE_BASE
2125 bool "Randomize the address of the kernel image (KASLR)"
2126 depends on RELOCATABLE
2129 In support of Kernel Address Space Layout Randomization (KASLR),
2130 this randomizes the physical address at which the kernel image
2131 is decompressed and the virtual address where the kernel
2132 image is mapped, as a security feature that deters exploit
2133 attempts relying on knowledge of the location of kernel
2136 On 64-bit, the kernel physical and virtual addresses are
2137 randomized separately. The physical address will be anywhere
2138 between 16MB and the top of physical memory (up to 64TB). The
2139 virtual address will be randomized from 16MB up to 1GB (9 bits
2140 of entropy). Note that this also reduces the memory space
2141 available to kernel modules from 1.5GB to 1GB.
2143 On 32-bit, the kernel physical and virtual addresses are
2144 randomized together. They will be randomized from 16MB up to
2145 512MB (8 bits of entropy).
2147 Entropy is generated using the RDRAND instruction if it is
2148 supported. If RDTSC is supported, its value is mixed into
2149 the entropy pool as well. If neither RDRAND nor RDTSC are
2150 supported, then entropy is read from the i8254 timer. The
2151 usable entropy is limited by the kernel being built using
2152 2GB addressing, and that PHYSICAL_ALIGN must be at a
2153 minimum of 2MB. As a result, only 10 bits of entropy are
2154 theoretically possible, but the implementations are further
2155 limited due to memory layouts.
2159 # Relocation on x86 needs some additional build support
2160 config X86_NEED_RELOCS
2162 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2164 config PHYSICAL_ALIGN
2165 hex "Alignment value to which kernel should be aligned"
2167 range 0x2000 0x1000000 if X86_32
2168 range 0x200000 0x1000000 if X86_64
2170 This value puts the alignment restrictions on physical address
2171 where kernel is loaded and run from. Kernel is compiled for an
2172 address which meets above alignment restriction.
2174 If bootloader loads the kernel at a non-aligned address and
2175 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2176 address aligned to above value and run from there.
2178 If bootloader loads the kernel at a non-aligned address and
2179 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2180 load address and decompress itself to the address it has been
2181 compiled for and run from there. The address for which kernel is
2182 compiled already meets above alignment restrictions. Hence the
2183 end result is that kernel runs from a physical address meeting
2184 above alignment restrictions.
2186 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2187 this value must be a multiple of 0x200000.
2189 Don't change this unless you know what you are doing.
2191 config DYNAMIC_MEMORY_LAYOUT
2194 This option makes base addresses of vmalloc and vmemmap as well as
2195 __PAGE_OFFSET movable during boot.
2197 config RANDOMIZE_MEMORY
2198 bool "Randomize the kernel memory sections"
2200 depends on RANDOMIZE_BASE
2201 select DYNAMIC_MEMORY_LAYOUT
2202 default RANDOMIZE_BASE
2204 Randomizes the base virtual address of kernel memory sections
2205 (physical memory mapping, vmalloc & vmemmap). This security feature
2206 makes exploits relying on predictable memory locations less reliable.
2208 The order of allocations remains unchanged. Entropy is generated in
2209 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2210 configuration have in average 30,000 different possible virtual
2211 addresses for each memory section.
2215 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2216 hex "Physical memory mapping padding" if EXPERT
2217 depends on RANDOMIZE_MEMORY
2218 default "0xa" if MEMORY_HOTPLUG
2220 range 0x1 0x40 if MEMORY_HOTPLUG
2223 Define the padding in terabytes added to the existing physical
2224 memory size during kernel memory randomization. It is useful
2225 for memory hotplug support but reduces the entropy available for
2226 address randomization.
2228 If unsure, leave at the default value.
2234 config BOOTPARAM_HOTPLUG_CPU0
2235 bool "Set default setting of cpu0_hotpluggable"
2236 depends on HOTPLUG_CPU
2238 Set whether default state of cpu0_hotpluggable is on or off.
2240 Say Y here to enable CPU0 hotplug by default. If this switch
2241 is turned on, there is no need to give cpu0_hotplug kernel
2242 parameter and the CPU0 hotplug feature is enabled by default.
2244 Please note: there are two known CPU0 dependencies if you want
2245 to enable the CPU0 hotplug feature either by this switch or by
2246 cpu0_hotplug kernel parameter.
2248 First, resume from hibernate or suspend always starts from CPU0.
2249 So hibernate and suspend are prevented if CPU0 is offline.
2251 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2252 offline if any interrupt can not migrate out of CPU0. There may
2253 be other CPU0 dependencies.
2255 Please make sure the dependencies are under your control before
2256 you enable this feature.
2258 Say N if you don't want to enable CPU0 hotplug feature by default.
2259 You still can enable the CPU0 hotplug feature at boot by kernel
2260 parameter cpu0_hotplug.
2262 config DEBUG_HOTPLUG_CPU0
2264 prompt "Debug CPU0 hotplug"
2265 depends on HOTPLUG_CPU
2267 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2268 soon as possible and boots up userspace with CPU0 offlined. User
2269 can online CPU0 back after boot time.
2271 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2272 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2273 compilation or giving cpu0_hotplug kernel parameter at boot.
2279 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2280 depends on COMPAT_32
2282 Certain buggy versions of glibc will crash if they are
2283 presented with a 32-bit vDSO that is not mapped at the address
2284 indicated in its segment table.
2286 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2287 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2288 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2289 the only released version with the bug, but OpenSUSE 9
2290 contains a buggy "glibc 2.3.2".
2292 The symptom of the bug is that everything crashes on startup, saying:
2293 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2295 Saying Y here changes the default value of the vdso32 boot
2296 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2297 This works around the glibc bug but hurts performance.
2299 If unsure, say N: if you are compiling your own kernel, you
2300 are unlikely to be using a buggy version of glibc.
2303 prompt "vsyscall table for legacy applications"
2305 default LEGACY_VSYSCALL_XONLY
2307 Legacy user code that does not know how to find the vDSO expects
2308 to be able to issue three syscalls by calling fixed addresses in
2309 kernel space. Since this location is not randomized with ASLR,
2310 it can be used to assist security vulnerability exploitation.
2312 This setting can be changed at boot time via the kernel command
2313 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2314 is deprecated and can only be enabled using the kernel command
2317 On a system with recent enough glibc (2.14 or newer) and no
2318 static binaries, you can say None without a performance penalty
2319 to improve security.
2321 If unsure, select "Emulate execution only".
2323 config LEGACY_VSYSCALL_XONLY
2324 bool "Emulate execution only"
2326 The kernel traps and emulates calls into the fixed vsyscall
2327 address mapping and does not allow reads. This
2328 configuration is recommended when userspace might use the
2329 legacy vsyscall area but support for legacy binary
2330 instrumentation of legacy code is not needed. It mitigates
2331 certain uses of the vsyscall area as an ASLR-bypassing
2334 config LEGACY_VSYSCALL_NONE
2337 There will be no vsyscall mapping at all. This will
2338 eliminate any risk of ASLR bypass due to the vsyscall
2339 fixed address mapping. Attempts to use the vsyscalls
2340 will be reported to dmesg, so that either old or
2341 malicious userspace programs can be identified.
2346 bool "Built-in kernel command line"
2348 Allow for specifying boot arguments to the kernel at
2349 build time. On some systems (e.g. embedded ones), it is
2350 necessary or convenient to provide some or all of the
2351 kernel boot arguments with the kernel itself (that is,
2352 to not rely on the boot loader to provide them.)
2354 To compile command line arguments into the kernel,
2355 set this option to 'Y', then fill in the
2356 boot arguments in CONFIG_CMDLINE.
2358 Systems with fully functional boot loaders (i.e. non-embedded)
2359 should leave this option set to 'N'.
2362 string "Built-in kernel command string"
2363 depends on CMDLINE_BOOL
2366 Enter arguments here that should be compiled into the kernel
2367 image and used at boot time. If the boot loader provides a
2368 command line at boot time, it is appended to this string to
2369 form the full kernel command line, when the system boots.
2371 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2372 change this behavior.
2374 In most cases, the command line (whether built-in or provided
2375 by the boot loader) should specify the device for the root
2378 config CMDLINE_OVERRIDE
2379 bool "Built-in command line overrides boot loader arguments"
2380 depends on CMDLINE_BOOL && CMDLINE != ""
2382 Set this option to 'Y' to have the kernel ignore the boot loader
2383 command line, and use ONLY the built-in command line.
2385 This is used to work around broken boot loaders. This should
2386 be set to 'N' under normal conditions.
2388 config MODIFY_LDT_SYSCALL
2389 bool "Enable the LDT (local descriptor table)" if EXPERT
2392 Linux can allow user programs to install a per-process x86
2393 Local Descriptor Table (LDT) using the modify_ldt(2) system
2394 call. This is required to run 16-bit or segmented code such as
2395 DOSEMU or some Wine programs. It is also used by some very old
2396 threading libraries.
2398 Enabling this feature adds a small amount of overhead to
2399 context switches and increases the low-level kernel attack
2400 surface. Disabling it removes the modify_ldt(2) system call.
2402 Saying 'N' here may make sense for embedded or server kernels.
2404 config STRICT_SIGALTSTACK_SIZE
2405 bool "Enforce strict size checking for sigaltstack"
2406 depends on DYNAMIC_SIGFRAME
2408 For historical reasons MINSIGSTKSZ is a constant which became
2409 already too small with AVX512 support. Add a mechanism to
2410 enforce strict checking of the sigaltstack size against the
2411 real size of the FPU frame. This option enables the check
2412 by default. It can also be controlled via the kernel command
2413 line option 'strict_sas_size' independent of this config
2414 switch. Enabling it might break existing applications which
2415 allocate a too small sigaltstack but 'work' because they
2416 never get a signal delivered.
2418 Say 'N' unless you want to really enforce this check.
2420 source "kernel/livepatch/Kconfig"
2425 def_bool $(cc-option,-mharden-sls=all)
2427 config CC_HAS_RETURN_THUNK
2428 def_bool $(cc-option,-mfunction-return=thunk-extern)
2430 menuconfig SPECULATION_MITIGATIONS
2431 bool "Mitigations for speculative execution vulnerabilities"
2434 Say Y here to enable options which enable mitigations for
2435 speculative execution hardware vulnerabilities.
2437 If you say N, all mitigations will be disabled. You really
2438 should know what you are doing to say so.
2440 if SPECULATION_MITIGATIONS
2442 config PAGE_TABLE_ISOLATION
2443 bool "Remove the kernel mapping in user mode"
2445 depends on (X86_64 || X86_PAE)
2447 This feature reduces the number of hardware side channels by
2448 ensuring that the majority of kernel addresses are not mapped
2451 See Documentation/x86/pti.rst for more details.
2454 bool "Avoid speculative indirect branches in kernel"
2455 select OBJTOOL if HAVE_OBJTOOL
2458 Compile kernel with the retpoline compiler options to guard against
2459 kernel-to-user data leaks by avoiding speculative indirect
2460 branches. Requires a compiler with -mindirect-branch=thunk-extern
2461 support for full protection. The kernel may run slower.
2464 bool "Enable return-thunks"
2465 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2466 select OBJTOOL if HAVE_OBJTOOL
2469 Compile the kernel with the return-thunks compiler option to guard
2470 against kernel-to-user data leaks by avoiding return speculation.
2471 Requires a compiler with -mfunction-return=thunk-extern
2472 support for full protection. The kernel may run slower.
2474 config CPU_UNRET_ENTRY
2475 bool "Enable UNRET on kernel entry"
2476 depends on CPU_SUP_AMD && RETHUNK && X86_64
2479 Compile the kernel with support for the retbleed=unret mitigation.
2481 config CPU_IBPB_ENTRY
2482 bool "Enable IBPB on kernel entry"
2483 depends on CPU_SUP_AMD && X86_64
2486 Compile the kernel with support for the retbleed=ibpb mitigation.
2488 config CPU_IBRS_ENTRY
2489 bool "Enable IBRS on kernel entry"
2490 depends on CPU_SUP_INTEL && X86_64
2493 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2494 This mitigates both spectre_v2 and retbleed at great cost to
2498 bool "Mitigate Straight-Line-Speculation"
2499 depends on CC_HAS_SLS && X86_64
2500 select OBJTOOL if HAVE_OBJTOOL
2503 Compile the kernel with straight-line-speculation options to guard
2504 against straight line speculation. The kernel image might be slightly
2509 config ARCH_HAS_ADD_PAGES
2511 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2513 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2516 menu "Power management and ACPI options"
2518 config ARCH_HIBERNATION_HEADER
2520 depends on HIBERNATION
2522 source "kernel/power/Kconfig"
2524 source "drivers/acpi/Kconfig"
2531 tristate "APM (Advanced Power Management) BIOS support"
2532 depends on X86_32 && PM_SLEEP
2534 APM is a BIOS specification for saving power using several different
2535 techniques. This is mostly useful for battery powered laptops with
2536 APM compliant BIOSes. If you say Y here, the system time will be
2537 reset after a RESUME operation, the /proc/apm device will provide
2538 battery status information, and user-space programs will receive
2539 notification of APM "events" (e.g. battery status change).
2541 If you select "Y" here, you can disable actual use of the APM
2542 BIOS by passing the "apm=off" option to the kernel at boot time.
2544 Note that the APM support is almost completely disabled for
2545 machines with more than one CPU.
2547 In order to use APM, you will need supporting software. For location
2548 and more information, read <file:Documentation/power/apm-acpi.rst>
2549 and the Battery Powered Linux mini-HOWTO, available from
2550 <http://www.tldp.org/docs.html#howto>.
2552 This driver does not spin down disk drives (see the hdparm(8)
2553 manpage ("man 8 hdparm") for that), and it doesn't turn off
2554 VESA-compliant "green" monitors.
2556 This driver does not support the TI 4000M TravelMate and the ACER
2557 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2558 desktop machines also don't have compliant BIOSes, and this driver
2559 may cause those machines to panic during the boot phase.
2561 Generally, if you don't have a battery in your machine, there isn't
2562 much point in using this driver and you should say N. If you get
2563 random kernel OOPSes or reboots that don't seem to be related to
2564 anything, try disabling/enabling this option (or disabling/enabling
2567 Some other things you should try when experiencing seemingly random,
2570 1) make sure that you have enough swap space and that it is
2572 2) pass the "no-hlt" option to the kernel
2573 3) switch on floating point emulation in the kernel and pass
2574 the "no387" option to the kernel
2575 4) pass the "floppy=nodma" option to the kernel
2576 5) pass the "mem=4M" option to the kernel (thereby disabling
2577 all but the first 4 MB of RAM)
2578 6) make sure that the CPU is not over clocked.
2579 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2580 8) disable the cache from your BIOS settings
2581 9) install a fan for the video card or exchange video RAM
2582 10) install a better fan for the CPU
2583 11) exchange RAM chips
2584 12) exchange the motherboard.
2586 To compile this driver as a module, choose M here: the
2587 module will be called apm.
2591 config APM_IGNORE_USER_SUSPEND
2592 bool "Ignore USER SUSPEND"
2594 This option will ignore USER SUSPEND requests. On machines with a
2595 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2596 series notebooks, it is necessary to say Y because of a BIOS bug.
2598 config APM_DO_ENABLE
2599 bool "Enable PM at boot time"
2601 Enable APM features at boot time. From page 36 of the APM BIOS
2602 specification: "When disabled, the APM BIOS does not automatically
2603 power manage devices, enter the Standby State, enter the Suspend
2604 State, or take power saving steps in response to CPU Idle calls."
2605 This driver will make CPU Idle calls when Linux is idle (unless this
2606 feature is turned off -- see "Do CPU IDLE calls", below). This
2607 should always save battery power, but more complicated APM features
2608 will be dependent on your BIOS implementation. You may need to turn
2609 this option off if your computer hangs at boot time when using APM
2610 support, or if it beeps continuously instead of suspending. Turn
2611 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2612 T400CDT. This is off by default since most machines do fine without
2617 bool "Make CPU Idle calls when idle"
2619 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2620 On some machines, this can activate improved power savings, such as
2621 a slowed CPU clock rate, when the machine is idle. These idle calls
2622 are made after the idle loop has run for some length of time (e.g.,
2623 333 mS). On some machines, this will cause a hang at boot time or
2624 whenever the CPU becomes idle. (On machines with more than one CPU,
2625 this option does nothing.)
2627 config APM_DISPLAY_BLANK
2628 bool "Enable console blanking using APM"
2630 Enable console blanking using the APM. Some laptops can use this to
2631 turn off the LCD backlight when the screen blanker of the Linux
2632 virtual console blanks the screen. Note that this is only used by
2633 the virtual console screen blanker, and won't turn off the backlight
2634 when using the X Window system. This also doesn't have anything to
2635 do with your VESA-compliant power-saving monitor. Further, this
2636 option doesn't work for all laptops -- it might not turn off your
2637 backlight at all, or it might print a lot of errors to the console,
2638 especially if you are using gpm.
2640 config APM_ALLOW_INTS
2641 bool "Allow interrupts during APM BIOS calls"
2643 Normally we disable external interrupts while we are making calls to
2644 the APM BIOS as a measure to lessen the effects of a badly behaving
2645 BIOS implementation. The BIOS should reenable interrupts if it
2646 needs to. Unfortunately, some BIOSes do not -- especially those in
2647 many of the newer IBM Thinkpads. If you experience hangs when you
2648 suspend, try setting this to Y. Otherwise, say N.
2652 source "drivers/cpufreq/Kconfig"
2654 source "drivers/cpuidle/Kconfig"
2656 source "drivers/idle/Kconfig"
2660 menu "Bus options (PCI etc.)"
2663 prompt "PCI access mode"
2664 depends on X86_32 && PCI
2667 On PCI systems, the BIOS can be used to detect the PCI devices and
2668 determine their configuration. However, some old PCI motherboards
2669 have BIOS bugs and may crash if this is done. Also, some embedded
2670 PCI-based systems don't have any BIOS at all. Linux can also try to
2671 detect the PCI hardware directly without using the BIOS.
2673 With this option, you can specify how Linux should detect the
2674 PCI devices. If you choose "BIOS", the BIOS will be used,
2675 if you choose "Direct", the BIOS won't be used, and if you
2676 choose "MMConfig", then PCI Express MMCONFIG will be used.
2677 If you choose "Any", the kernel will try MMCONFIG, then the
2678 direct access method and falls back to the BIOS if that doesn't
2679 work. If unsure, go with the default, which is "Any".
2684 config PCI_GOMMCONFIG
2701 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2703 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2706 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2709 bool "Support mmconfig PCI config space access" if X86_64
2711 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2712 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2716 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2720 depends on PCI && XEN
2722 config MMCONF_FAM10H
2724 depends on X86_64 && PCI_MMCONFIG && ACPI
2726 config PCI_CNB20LE_QUIRK
2727 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2730 Read the PCI windows out of the CNB20LE host bridge. This allows
2731 PCI hotplug to work on systems with the CNB20LE chipset which do
2734 There's no public spec for this chipset, and this functionality
2735 is known to be incomplete.
2737 You should say N unless you know you need this.
2740 bool "ISA bus support on modern systems" if EXPERT
2742 Expose ISA bus device drivers and options available for selection and
2743 configuration. Enable this option if your target machine has an ISA
2744 bus. ISA is an older system, displaced by PCI and newer bus
2745 architectures -- if your target machine is modern, it probably does
2746 not have an ISA bus.
2750 # x86_64 have no ISA slots, but can have ISA-style DMA.
2752 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2755 Enables ISA-style DMA support for devices requiring such controllers.
2763 Find out whether you have ISA slots on your motherboard. ISA is the
2764 name of a bus system, i.e. the way the CPU talks to the other stuff
2765 inside your box. Other bus systems are PCI, EISA, MicroChannel
2766 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2767 newer boards don't support it. If you have ISA, say Y, otherwise N.
2770 tristate "NatSemi SCx200 support"
2772 This provides basic support for National Semiconductor's
2773 (now AMD's) Geode processors. The driver probes for the
2774 PCI-IDs of several on-chip devices, so its a good dependency
2775 for other scx200_* drivers.
2777 If compiled as a module, the driver is named scx200.
2779 config SCx200HR_TIMER
2780 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2784 This driver provides a clocksource built upon the on-chip
2785 27MHz high-resolution timer. Its also a workaround for
2786 NSC Geode SC-1100's buggy TSC, which loses time when the
2787 processor goes idle (as is done by the scheduler). The
2788 other workaround is idle=poll boot option.
2791 bool "One Laptop Per Child support"
2799 Add support for detecting the unique features of the OLPC
2803 bool "OLPC XO-1 Power Management"
2804 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2806 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2809 bool "OLPC XO-1 Real Time Clock"
2810 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2812 Add support for the XO-1 real time clock, which can be used as a
2813 programmable wakeup source.
2816 bool "OLPC XO-1 SCI extras"
2817 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2821 Add support for SCI-based features of the OLPC XO-1 laptop:
2822 - EC-driven system wakeups
2826 - AC adapter status updates
2827 - Battery status updates
2829 config OLPC_XO15_SCI
2830 bool "OLPC XO-1.5 SCI extras"
2831 depends on OLPC && ACPI
2834 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2835 - EC-driven system wakeups
2836 - AC adapter status updates
2837 - Battery status updates
2840 bool "PCEngines ALIX System Support (LED setup)"
2843 This option enables system support for the PCEngines ALIX.
2844 At present this just sets up LEDs for GPIO control on
2845 ALIX2/3/6 boards. However, other system specific setup should
2848 Note: You must still enable the drivers for GPIO and LED support
2849 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2851 Note: You have to set alix.force=1 for boards with Award BIOS.
2854 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2857 This option enables system support for the Soekris Engineering net5501.
2860 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2864 This option enables system support for the Traverse Technologies GEOS.
2867 bool "Technologic Systems TS-5500 platform support"
2869 select CHECK_SIGNATURE
2873 This option enables system support for the Technologic Systems TS-5500.
2879 depends on CPU_SUP_AMD && PCI
2883 menu "Binary Emulations"
2885 config IA32_EMULATION
2886 bool "IA32 Emulation"
2888 select ARCH_WANT_OLD_COMPAT_IPC
2890 select COMPAT_OLD_SIGACTION
2892 Include code to run legacy 32-bit programs under a
2893 64-bit kernel. You should likely turn this on, unless you're
2894 100% sure that you don't have any 32-bit programs left.
2897 bool "x32 ABI for 64-bit mode"
2899 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2900 # compressed debug sections to x86_x32 properly:
2901 # https://github.com/ClangBuiltLinux/linux/issues/514
2902 # https://github.com/ClangBuiltLinux/linux/issues/1141
2903 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2905 Include code to run binaries for the x32 native 32-bit ABI
2906 for 64-bit processors. An x32 process gets access to the
2907 full 64-bit register file and wide data path while leaving
2908 pointers at 32 bits for smaller memory footprint.
2912 depends on IA32_EMULATION || X86_32
2914 select OLD_SIGSUSPEND3
2918 depends on IA32_EMULATION || X86_X32_ABI
2920 config COMPAT_FOR_U64_ALIGNMENT
2926 config HAVE_ATOMIC_IOMAP
2930 source "arch/x86/kvm/Kconfig"
2932 source "arch/x86/Kconfig.assembler"