1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
71 select ARCH_HAS_CACHE_LINE_SIZE
72 select ARCH_HAS_CURRENT_STACK_POINTER
73 select ARCH_HAS_DEBUG_VIRTUAL
74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
75 select ARCH_HAS_DEVMEM_IS_ALLOWED
76 select ARCH_HAS_EARLY_DEBUG if KGDB
77 select ARCH_HAS_ELF_RANDOMIZE
78 select ARCH_HAS_FAST_MULTIPLIER
79 select ARCH_HAS_FORTIFY_SOURCE
80 select ARCH_HAS_GCOV_PROFILE_ALL
81 select ARCH_HAS_KCOV if X86_64
82 select ARCH_HAS_MEM_ENCRYPT
83 select ARCH_HAS_MEMBARRIER_SYNC_CORE
84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85 select ARCH_HAS_PMEM_API if X86_64
86 select ARCH_HAS_PTE_DEVMAP if X86_64
87 select ARCH_HAS_PTE_SPECIAL
88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
89 select ARCH_HAS_COPY_MC if X86_64
90 select ARCH_HAS_SET_MEMORY
91 select ARCH_HAS_SET_DIRECT_MAP
92 select ARCH_HAS_STRICT_KERNEL_RWX
93 select ARCH_HAS_STRICT_MODULE_RWX
94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95 select ARCH_HAS_SYSCALL_WRAPPER
96 select ARCH_HAS_UBSAN_SANITIZE_ALL
97 select ARCH_HAS_VM_GET_PAGE_PROT
98 select ARCH_HAS_DEBUG_WX
99 select ARCH_HAS_ZONE_DMA_SET if EXPERT
100 select ARCH_HAVE_NMI_SAFE_CMPXCHG
101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
102 select ARCH_MIGHT_HAVE_PC_PARPORT
103 select ARCH_MIGHT_HAVE_PC_SERIO
104 select ARCH_STACKWALK
105 select ARCH_SUPPORTS_ACPI
106 select ARCH_SUPPORTS_ATOMIC_RMW
107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
111 select ARCH_SUPPORTS_LTO_CLANG
112 select ARCH_SUPPORTS_LTO_CLANG_THIN
113 select ARCH_USE_BUILTIN_BSWAP
114 select ARCH_USE_MEMTEST
115 select ARCH_USE_QUEUED_RWLOCKS
116 select ARCH_USE_QUEUED_SPINLOCKS
117 select ARCH_USE_SYM_ANNOTATIONS
118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
121 select ARCH_WANTS_NO_INSTR
122 select ARCH_WANT_GENERAL_HUGETLB
123 select ARCH_WANT_HUGE_PMD_SHARE
124 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
125 select ARCH_WANT_LD_ORPHAN_WARN
126 select ARCH_WANTS_THP_SWAP if X86_64
127 select ARCH_HAS_PARANOID_L1D_FLUSH
128 select BUILDTIME_TABLE_SORT
130 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
131 select CLOCKSOURCE_WATCHDOG
132 select DCACHE_WORD_ACCESS
133 select DYNAMIC_SIGFRAME
134 select EDAC_ATOMIC_SCRUB
136 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
137 select GENERIC_CLOCKEVENTS_MIN_ADJUST
138 select GENERIC_CMOS_UPDATE
139 select GENERIC_CPU_AUTOPROBE
140 select GENERIC_CPU_VULNERABILITIES
141 select GENERIC_EARLY_IOREMAP
144 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
145 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
146 select GENERIC_IRQ_MIGRATION if SMP
147 select GENERIC_IRQ_PROBE
148 select GENERIC_IRQ_RESERVATION_MODE
149 select GENERIC_IRQ_SHOW
150 select GENERIC_PENDING_IRQ if SMP
151 select GENERIC_PTDUMP
152 select GENERIC_SMP_IDLE_THREAD
153 select GENERIC_TIME_VSYSCALL
154 select GENERIC_GETTIMEOFDAY
155 select GENERIC_VDSO_TIME_NS
156 select GUP_GET_PTE_LOW_HIGH if X86_PAE
157 select HARDIRQS_SW_RESEND
158 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
159 select HAVE_ACPI_APEI if ACPI
160 select HAVE_ACPI_APEI_NMI if ACPI
161 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
162 select HAVE_ARCH_AUDITSYSCALL
163 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
164 select HAVE_ARCH_HUGE_VMALLOC if X86_64
165 select HAVE_ARCH_JUMP_LABEL
166 select HAVE_ARCH_JUMP_LABEL_RELATIVE
167 select HAVE_ARCH_KASAN if X86_64
168 select HAVE_ARCH_KASAN_VMALLOC if X86_64
169 select HAVE_ARCH_KFENCE
170 select HAVE_ARCH_KGDB
171 select HAVE_ARCH_MMAP_RND_BITS if MMU
172 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
173 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
174 select HAVE_ARCH_PREL32_RELOCATIONS
175 select HAVE_ARCH_SECCOMP_FILTER
176 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
177 select HAVE_ARCH_STACKLEAK
178 select HAVE_ARCH_TRACEHOOK
179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
181 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
182 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
183 select HAVE_ARCH_VMAP_STACK if X86_64
184 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
185 select HAVE_ARCH_WITHIN_STACK_FRAMES
186 select HAVE_ASM_MODVERSIONS
187 select HAVE_CMPXCHG_DOUBLE
188 select HAVE_CMPXCHG_LOCAL
189 select HAVE_CONTEXT_TRACKING_USER if X86_64
190 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
191 select HAVE_C_RECORDMCOUNT
192 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
193 select HAVE_BUILDTIME_MCOUNT_SORT
194 select HAVE_DEBUG_KMEMLEAK
195 select HAVE_DMA_CONTIGUOUS
196 select HAVE_DYNAMIC_FTRACE
197 select HAVE_DYNAMIC_FTRACE_WITH_REGS
198 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
199 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
200 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
201 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
203 select HAVE_EFFICIENT_UNALIGNED_ACCESS
205 select HAVE_EXIT_THREAD
207 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
208 select HAVE_FTRACE_MCOUNT_RECORD
209 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
210 select HAVE_FUNCTION_TRACER
211 select HAVE_GCC_PLUGINS
212 select HAVE_HW_BREAKPOINT
213 select HAVE_IOREMAP_PROT
214 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
215 select HAVE_IRQ_TIME_ACCOUNTING
216 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
217 select HAVE_KERNEL_BZIP2
218 select HAVE_KERNEL_GZIP
219 select HAVE_KERNEL_LZ4
220 select HAVE_KERNEL_LZMA
221 select HAVE_KERNEL_LZO
222 select HAVE_KERNEL_XZ
223 select HAVE_KERNEL_ZSTD
225 select HAVE_KPROBES_ON_FTRACE
226 select HAVE_FUNCTION_ERROR_INJECTION
227 select HAVE_KRETPROBES
230 select HAVE_LIVEPATCH if X86_64
231 select HAVE_MIXED_BREAKPOINTS_REGS
232 select HAVE_MOD_ARCH_SPECIFIC
235 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
237 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
238 select HAVE_OBJTOOL if X86_64
239 select HAVE_OPTPROBES
240 select HAVE_PCSPKR_PLATFORM
241 select HAVE_PERF_EVENTS
242 select HAVE_PERF_EVENTS_NMI
243 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
245 select HAVE_PERF_REGS
246 select HAVE_PERF_USER_STACK_DUMP
247 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
248 select MMU_GATHER_MERGE_VMAS
249 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
250 select HAVE_REGS_AND_STACK_ACCESS_API
251 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
252 select HAVE_FUNCTION_ARG_ACCESS_API
253 select HAVE_SETUP_PER_CPU_AREA
254 select HAVE_SOFTIRQ_ON_OWN_STACK
255 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
256 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
257 select HAVE_STATIC_CALL
258 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
259 select HAVE_PREEMPT_DYNAMIC_CALL
261 select HAVE_SYSCALL_TRACEPOINTS
262 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
263 select HAVE_UNSTABLE_SCHED_CLOCK
264 select HAVE_USER_RETURN_NOTIFIER
265 select HAVE_GENERIC_VDSO
266 select HOTPLUG_SMT if SMP
267 select IRQ_FORCED_THREADING
268 select NEED_PER_CPU_EMBED_FIRST_CHUNK
269 select NEED_PER_CPU_PAGE_FIRST_CHUNK
270 select NEED_SG_DMA_LENGTH
271 select PCI_DOMAINS if PCI
272 select PCI_LOCKLESS_CONFIG if PCI
275 select RTC_MC146818_LIB
278 select SYSCTL_EXCEPTION_TRACE
279 select THREAD_INFO_IN_TASK
280 select TRACE_IRQFLAGS_SUPPORT
281 select TRACE_IRQFLAGS_NMI_SUPPORT
282 select USER_STACKTRACE_SUPPORT
284 select HAVE_ARCH_KCSAN if X86_64
285 select X86_FEATURE_NAMES if PROC_FS
286 select PROC_PID_ARCH_STATUS if PROC_FS
287 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
288 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
290 config INSTRUCTION_DECODER
292 depends on KPROBES || PERF_EVENTS || UPROBES
296 default "elf32-i386" if X86_32
297 default "elf64-x86-64" if X86_64
299 config LOCKDEP_SUPPORT
302 config STACKTRACE_SUPPORT
308 config ARCH_MMAP_RND_BITS_MIN
312 config ARCH_MMAP_RND_BITS_MAX
316 config ARCH_MMAP_RND_COMPAT_BITS_MIN
319 config ARCH_MMAP_RND_COMPAT_BITS_MAX
325 config GENERIC_ISA_DMA
327 depends on ISA_DMA_API
332 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
334 config GENERIC_BUG_RELATIVE_POINTERS
337 config ARCH_MAY_HAVE_PC_FDC
339 depends on ISA_DMA_API
341 config GENERIC_CALIBRATE_DELAY
344 config ARCH_HAS_CPU_RELAX
347 config ARCH_HIBERNATION_POSSIBLE
352 default 1024 if X86_64
355 config ARCH_SUSPEND_POSSIBLE
361 config KASAN_SHADOW_OFFSET
364 default 0xdffffc0000000000
366 config HAVE_INTEL_TXT
368 depends on INTEL_IOMMU && ACPI
372 depends on X86_32 && SMP
376 depends on X86_64 && SMP
378 config ARCH_SUPPORTS_UPROBES
381 config FIX_EARLYCON_MEM
384 config DYNAMIC_PHYSICAL_MASK
387 config PGTABLE_LEVELS
389 default 5 if X86_5LEVEL
394 config CC_HAS_SANE_STACKPROTECTOR
396 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
397 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
399 We have to make sure stack protector is unconditionally disabled if
400 the compiler produces broken code or if it does not let us control
401 the segment on 32-bit kernels.
403 menu "Processor type and features"
406 bool "Symmetric multi-processing support"
408 This enables support for systems with more than one CPU. If you have
409 a system with only one CPU, say N. If you have a system with more
412 If you say N here, the kernel will run on uni- and multiprocessor
413 machines, but will use only one CPU of a multiprocessor machine. If
414 you say Y here, the kernel will run on many, but not all,
415 uniprocessor machines. On a uniprocessor machine, the kernel
416 will run faster if you say N here.
418 Note that if you say Y here and choose architecture "586" or
419 "Pentium" under "Processor family", the kernel will not work on 486
420 architectures. Similarly, multiprocessor kernels for the "PPro"
421 architecture may not work on all Pentium based boards.
423 People using multiprocessor machines who say Y here should also say
424 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
425 Management" code will be disabled if you say Y here.
427 See also <file:Documentation/x86/i386/IO-APIC.rst>,
428 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
429 <http://www.tldp.org/docs.html#howto>.
431 If you don't know what to do here, say N.
433 config X86_FEATURE_NAMES
434 bool "Processor feature human-readable names" if EMBEDDED
437 This option compiles in a table of x86 feature bits and corresponding
438 names. This is required to support /proc/cpuinfo and a few kernel
439 messages. You can disable this to save space, at the expense of
440 making those few kernel messages show numeric feature bits instead.
445 bool "Support x2apic"
446 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
448 This enables x2apic support on CPUs that have this feature.
450 This allows 32-bit apic IDs (so it can support very large systems),
451 and accesses the local apic via MSRs not via mmio.
453 If you don't know what to do here, say N.
456 bool "Enable MPS table" if ACPI
458 depends on X86_LOCAL_APIC
460 For old smp systems that do not have proper acpi support. Newer systems
461 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
465 depends on X86_GOLDFISH
467 config X86_CPU_RESCTRL
468 bool "x86 CPU resource control support"
469 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
471 select PROC_CPU_RESCTRL if PROC_FS
473 Enable x86 CPU resource control support.
475 Provide support for the allocation and monitoring of system resources
478 Intel calls this Intel Resource Director Technology
479 (Intel(R) RDT). More information about RDT can be found in the
480 Intel x86 Architecture Software Developer Manual.
482 AMD calls this AMD Platform Quality of Service (AMD QoS).
483 More information about AMD QoS can be found in the AMD64 Technology
484 Platform Quality of Service Extensions manual.
490 bool "Support for big SMP systems with more than 8 CPUs"
493 This option is needed for the systems that have more than 8 CPUs.
495 config X86_EXTENDED_PLATFORM
496 bool "Support for extended (non-PC) x86 platforms"
499 If you disable this option then the kernel will only support
500 standard PC platforms. (which covers the vast majority of
503 If you enable this option then you'll be able to select support
504 for the following (non-PC) 32 bit x86 platforms:
505 Goldfish (Android emulator)
508 SGI 320/540 (Visual Workstation)
509 STA2X11-based (e.g. Northville)
510 Moorestown MID devices
512 If you have one of these systems, or if you want to build a
513 generic distribution kernel, say Y here - otherwise say N.
517 config X86_EXTENDED_PLATFORM
518 bool "Support for extended (non-PC) x86 platforms"
521 If you disable this option then the kernel will only support
522 standard PC platforms. (which covers the vast majority of
525 If you enable this option then you'll be able to select support
526 for the following (non-PC) 64 bit x86 platforms:
531 If you have one of these systems, or if you want to build a
532 generic distribution kernel, say Y here - otherwise say N.
534 # This is an alphabetically sorted list of 64 bit extended platforms
535 # Please maintain the alphabetic order if and when there are additions
537 bool "Numascale NumaChip"
539 depends on X86_EXTENDED_PLATFORM
542 depends on X86_X2APIC
543 depends on PCI_MMCONFIG
545 Adds support for Numascale NumaChip large-SMP systems. Needed to
546 enable more than ~168 cores.
547 If you don't have one of these, you should say N here.
551 select HYPERVISOR_GUEST
553 depends on X86_64 && PCI
554 depends on X86_EXTENDED_PLATFORM
557 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
558 supposed to run on these EM64T-based machines. Only choose this option
559 if you have one of these machines.
562 bool "SGI Ultraviolet"
564 depends on X86_EXTENDED_PLATFORM
567 depends on KEXEC_CORE
568 depends on X86_X2APIC
571 This option is needed in order to support SGI Ultraviolet systems.
572 If you don't have one of these, you should say N here.
574 # Following is an alphabetically sorted list of 32 bit extended platforms
575 # Please maintain the alphabetic order if and when there are additions
578 bool "Goldfish (Virtual Platform)"
579 depends on X86_EXTENDED_PLATFORM
581 Enable support for the Goldfish virtual platform used primarily
582 for Android development. Unless you are building for the Android
583 Goldfish emulator say N here.
586 bool "CE4100 TV platform"
588 depends on PCI_GODIRECT
589 depends on X86_IO_APIC
591 depends on X86_EXTENDED_PLATFORM
592 select X86_REBOOTFIXUPS
594 select OF_EARLY_FLATTREE
596 Select for the Intel CE media processor (CE4100) SOC.
597 This option compiles in support for the CE4100 SOC for settop
598 boxes and media devices.
601 bool "Intel MID platform support"
602 depends on X86_EXTENDED_PLATFORM
603 depends on X86_PLATFORM_DEVICES
605 depends on X86_64 || (PCI_GOANY && X86_32)
606 depends on X86_IO_APIC
611 Select to build a kernel capable of supporting Intel MID (Mobile
612 Internet Device) platform systems which do not have the PCI legacy
613 interfaces. If you are building for a PC class system say N here.
615 Intel MID platforms are based on an Intel processor and chipset which
616 consume less power than most of the x86 derivatives.
618 config X86_INTEL_QUARK
619 bool "Intel Quark platform support"
621 depends on X86_EXTENDED_PLATFORM
622 depends on X86_PLATFORM_DEVICES
626 depends on X86_IO_APIC
631 Select to include support for Quark X1000 SoC.
632 Say Y here if you have a Quark based system such as the Arduino
633 compatible Intel Galileo.
635 config X86_INTEL_LPSS
636 bool "Intel Low Power Subsystem Support"
637 depends on X86 && ACPI && PCI
642 Select to build support for Intel Low Power Subsystem such as
643 found on Intel Lynxpoint PCH. Selecting this option enables
644 things like clock tree (common clock framework) and pincontrol
645 which are needed by the LPSS peripheral drivers.
647 config X86_AMD_PLATFORM_DEVICE
648 bool "AMD ACPI2Platform devices support"
653 Select to interpret AMD specific ACPI device to platform device
654 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
655 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
656 implemented under PINCTRL subsystem.
659 tristate "Intel SoC IOSF Sideband support for SoC platforms"
662 This option enables sideband register access support for Intel SoC
663 platforms. On these platforms the IOSF sideband is used in lieu of
664 MSR's for some register accesses, mostly but not limited to thermal
665 and power. Drivers may query the availability of this device to
666 determine if they need the sideband in order to work on these
667 platforms. The sideband is available on the following SoC products.
668 This list is not meant to be exclusive.
673 You should say Y if you are running a kernel on one of these SoC's.
675 config IOSF_MBI_DEBUG
676 bool "Enable IOSF sideband access through debugfs"
677 depends on IOSF_MBI && DEBUG_FS
679 Select this option to expose the IOSF sideband access registers (MCR,
680 MDR, MCRX) through debugfs to write and read register information from
681 different units on the SoC. This is most useful for obtaining device
682 state information for debug and analysis. As this is a general access
683 mechanism, users of this option would have specific knowledge of the
684 device they want to access.
686 If you don't require the option or are in doubt, say N.
689 bool "RDC R-321x SoC"
691 depends on X86_EXTENDED_PLATFORM
693 select X86_REBOOTFIXUPS
695 This option is needed for RDC R-321x system-on-chip, also known
697 If you don't have one of these chips, you should say N here.
699 config X86_32_NON_STANDARD
700 bool "Support non-standard 32-bit SMP architectures"
701 depends on X86_32 && SMP
702 depends on X86_EXTENDED_PLATFORM
704 This option compiles in the bigsmp and STA2X11 default
705 subarchitectures. It is intended for a generic binary
706 kernel. If you select them all, kernel will probe it one by
707 one and will fallback to default.
709 # Alphabetically sorted list of Non standard 32 bit platforms
711 config X86_SUPPORTS_MEMORY_FAILURE
713 # MCE code calls memory_failure():
715 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
716 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
717 depends on X86_64 || !SPARSEMEM
718 select ARCH_SUPPORTS_MEMORY_FAILURE
721 bool "STA2X11 Companion Chip Support"
722 depends on X86_32_NON_STANDARD && PCI
727 This adds support for boards based on the STA2X11 IO-Hub,
728 a.k.a. "ConneXt". The chip is used in place of the standard
729 PC chipset, so all "standard" peripherals are missing. If this
730 option is selected the kernel will still be able to boot on
731 standard PC machines.
734 tristate "Eurobraille/Iris poweroff module"
737 The Iris machines from EuroBraille do not have APM or ACPI support
738 to shut themselves down properly. A special I/O sequence is
739 needed to do so, which is what this module does at
742 This is only for Iris machines from EuroBraille.
746 config SCHED_OMIT_FRAME_POINTER
748 prompt "Single-depth WCHAN output"
751 Calculate simpler /proc/<PID>/wchan values. If this option
752 is disabled then wchan values will recurse back to the
753 caller function. This provides more accurate wchan values,
754 at the expense of slightly more scheduling overhead.
756 If in doubt, say "Y".
758 menuconfig HYPERVISOR_GUEST
759 bool "Linux guest support"
761 Say Y here to enable options for running Linux under various hyper-
762 visors. This option enables basic hypervisor detection and platform
765 If you say N, all options in this submenu will be skipped and
766 disabled, and Linux guest support won't be built in.
771 bool "Enable paravirtualization code"
772 depends on HAVE_STATIC_CALL
774 This changes the kernel so it can modify itself when it is run
775 under a hypervisor, potentially improving performance significantly
776 over full virtualization. However, when run without a hypervisor
777 the kernel is theoretically slower and slightly larger.
782 config PARAVIRT_DEBUG
783 bool "paravirt-ops debugging"
784 depends on PARAVIRT && DEBUG_KERNEL
786 Enable to debug paravirt_ops internals. Specifically, BUG if
787 a paravirt_op is missing when it is called.
789 config PARAVIRT_SPINLOCKS
790 bool "Paravirtualization layer for spinlocks"
791 depends on PARAVIRT && SMP
793 Paravirtualized spinlocks allow a pvops backend to replace the
794 spinlock implementation with something virtualization-friendly
795 (for example, block the virtual CPU rather than spinning).
797 It has a minimal impact on native kernels and gives a nice performance
798 benefit on paravirtualized KVM / Xen kernels.
800 If you are unsure how to answer this question, answer Y.
802 config X86_HV_CALLBACK_VECTOR
805 source "arch/x86/xen/Kconfig"
808 bool "KVM Guest support (including kvmclock)"
810 select PARAVIRT_CLOCK
811 select ARCH_CPUIDLE_HALTPOLL
812 select X86_HV_CALLBACK_VECTOR
815 This option enables various optimizations for running under the KVM
816 hypervisor. It includes a paravirtualized clock, so that instead
817 of relying on a PIT (or probably other) emulation by the
818 underlying device model, the host provides the guest with
819 timing infrastructure such as time of day, and system time
821 config ARCH_CPUIDLE_HALTPOLL
823 prompt "Disable host haltpoll when loading haltpoll driver"
825 If virtualized under KVM, disable host haltpoll.
828 bool "Support for running PVH guests"
830 This option enables the PVH entry point for guest virtual machines
831 as specified in the x86/HVM direct boot ABI.
833 config PARAVIRT_TIME_ACCOUNTING
834 bool "Paravirtual steal time accounting"
837 Select this option to enable fine granularity task steal time
838 accounting. Time spent executing other tasks in parallel with
839 the current vCPU is discounted from the vCPU power. To account for
840 that, there can be a small performance impact.
842 If in doubt, say N here.
844 config PARAVIRT_CLOCK
847 config JAILHOUSE_GUEST
848 bool "Jailhouse non-root cell support"
849 depends on X86_64 && PCI
852 This option allows to run Linux as guest in a Jailhouse non-root
853 cell. You can leave this option disabled if you only want to start
854 Jailhouse and run Linux afterwards in the root cell.
857 bool "ACRN Guest support"
859 select X86_HV_CALLBACK_VECTOR
861 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
862 a flexible, lightweight reference open-source hypervisor, built with
863 real-time and safety-criticality in mind. It is built for embedded
864 IOT with small footprint and real-time features. More details can be
865 found in https://projectacrn.org/.
867 config INTEL_TDX_GUEST
868 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
869 depends on X86_64 && CPU_SUP_INTEL
870 depends on X86_X2APIC
871 select ARCH_HAS_CC_PLATFORM
872 select X86_MEM_ENCRYPT
875 Support running as a guest under Intel TDX. Without this support,
876 the guest kernel can not boot or run under TDX.
877 TDX includes memory encryption and integrity capabilities
878 which protect the confidentiality and integrity of guest
879 memory contents and CPU state. TDX guests are protected from
880 some attacks from the VMM.
882 endif # HYPERVISOR_GUEST
884 source "arch/x86/Kconfig.cpu"
888 prompt "HPET Timer Support" if X86_32
890 Use the IA-PC HPET (High Precision Event Timer) to manage
891 time in preference to the PIT and RTC, if a HPET is
893 HPET is the next generation timer replacing legacy 8254s.
894 The HPET provides a stable time base on SMP
895 systems, unlike the TSC, but it is more expensive to access,
896 as it is off-chip. The interface used is documented
897 in the HPET spec, revision 1.
899 You can safely choose Y here. However, HPET will only be
900 activated if the platform and the BIOS support this feature.
901 Otherwise the 8254 will be used for timing services.
903 Choose N to continue using the legacy 8254 timer.
905 config HPET_EMULATE_RTC
907 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
909 # Mark as expert because too many people got it wrong.
910 # The code disables itself when not needed.
913 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
914 bool "Enable DMI scanning" if EXPERT
916 Enabled scanning of DMI to identify machine quirks. Say Y
917 here unless you have verified that your setup is not
918 affected by entries in the DMI blacklist. Required by PNP
922 bool "Old AMD GART IOMMU support"
926 depends on X86_64 && PCI && AMD_NB
928 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
929 GART based hardware IOMMUs.
931 The GART supports full DMA access for devices with 32-bit access
932 limitations, on systems with more than 3 GB. This is usually needed
933 for USB, sound, many IDE/SATA chipsets and some other devices.
935 Newer systems typically have a modern AMD IOMMU, supported via
936 the CONFIG_AMD_IOMMU=y config option.
938 In normal configurations this driver is only active when needed:
939 there's more than 3 GB of memory and the system contains a
940 32-bit limited device.
944 config BOOT_VESA_SUPPORT
947 If true, at least one selected framebuffer driver can take advantage
948 of VESA video modes set at an early boot stage via the vga= parameter.
951 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
952 depends on X86_64 && SMP && DEBUG_KERNEL
953 select CPUMASK_OFFSTACK
955 Enable maximum number of CPUS and NUMA Nodes for this architecture.
959 # The maximum number of CPUs supported:
961 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
962 # and which can be configured interactively in the
963 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
965 # The ranges are different on 32-bit and 64-bit kernels, depending on
966 # hardware capabilities and scalability features of the kernel.
968 # ( If MAXSMP is enabled we just use the highest possible value and disable
969 # interactive configuration. )
972 config NR_CPUS_RANGE_BEGIN
974 default NR_CPUS_RANGE_END if MAXSMP
978 config NR_CPUS_RANGE_END
981 default 64 if SMP && X86_BIGSMP
982 default 8 if SMP && !X86_BIGSMP
985 config NR_CPUS_RANGE_END
988 default 8192 if SMP && CPUMASK_OFFSTACK
989 default 512 if SMP && !CPUMASK_OFFSTACK
992 config NR_CPUS_DEFAULT
995 default 32 if X86_BIGSMP
999 config NR_CPUS_DEFAULT
1002 default 8192 if MAXSMP
1007 int "Maximum number of CPUs" if SMP && !MAXSMP
1008 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1009 default NR_CPUS_DEFAULT
1011 This allows you to specify the maximum number of CPUs which this
1012 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1013 supported value is 8192, otherwise the maximum value is 512. The
1014 minimum value which makes sense is 2.
1016 This is purely to save memory: each supported CPU adds about 8KB
1017 to the kernel image.
1019 config SCHED_CLUSTER
1020 bool "Cluster scheduler support"
1024 Cluster scheduler support improves the CPU scheduler's decision
1025 making when dealing with machines that have clusters of CPUs.
1026 Cluster usually means a couple of CPUs which are placed closely
1027 by sharing mid-level caches, last-level cache tags or internal
1035 prompt "Multi-core scheduler support"
1038 Multi-core scheduler support improves the CPU scheduler's decision
1039 making when dealing with multi-core CPU chips at a cost of slightly
1040 increased overhead in some places. If unsure say N here.
1042 config SCHED_MC_PRIO
1043 bool "CPU core priorities scheduler support"
1044 depends on SCHED_MC && CPU_SUP_INTEL
1045 select X86_INTEL_PSTATE
1049 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1050 core ordering determined at manufacturing time, which allows
1051 certain cores to reach higher turbo frequencies (when running
1052 single threaded workloads) than others.
1054 Enabling this kernel feature teaches the scheduler about
1055 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1056 scheduler's CPU selection logic accordingly, so that higher
1057 overall system performance can be achieved.
1059 This feature will have no effect on CPUs without this feature.
1061 If unsure say Y here.
1065 depends on !SMP && X86_LOCAL_APIC
1068 bool "Local APIC support on uniprocessors" if !PCI_MSI
1070 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1072 A local APIC (Advanced Programmable Interrupt Controller) is an
1073 integrated interrupt controller in the CPU. If you have a single-CPU
1074 system which has a processor with a local APIC, you can say Y here to
1075 enable and use it. If you say Y here even though your machine doesn't
1076 have a local APIC, then the kernel will still run with no slowdown at
1077 all. The local APIC supports CPU-generated self-interrupts (timer,
1078 performance counters), and the NMI watchdog which detects hard
1081 config X86_UP_IOAPIC
1082 bool "IO-APIC support on uniprocessors"
1083 depends on X86_UP_APIC
1085 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1086 SMP-capable replacement for PC-style interrupt controllers. Most
1087 SMP systems and many recent uniprocessor systems have one.
1089 If you have a single-CPU system with an IO-APIC, you can say Y here
1090 to use it. If you say Y here even though your machine doesn't have
1091 an IO-APIC, then the kernel will still run with no slowdown at all.
1093 config X86_LOCAL_APIC
1095 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1096 select IRQ_DOMAIN_HIERARCHY
1097 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1101 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1103 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1104 bool "Reroute for broken boot IRQs"
1105 depends on X86_IO_APIC
1107 This option enables a workaround that fixes a source of
1108 spurious interrupts. This is recommended when threaded
1109 interrupt handling is used on systems where the generation of
1110 superfluous "boot interrupts" cannot be disabled.
1112 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1113 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1114 kernel does during interrupt handling). On chipsets where this
1115 boot IRQ generation cannot be disabled, this workaround keeps
1116 the original IRQ line masked so that only the equivalent "boot
1117 IRQ" is delivered to the CPUs. The workaround also tells the
1118 kernel to set up the IRQ handler on the boot IRQ line. In this
1119 way only one interrupt is delivered to the kernel. Otherwise
1120 the spurious second interrupt may cause the kernel to bring
1121 down (vital) interrupt lines.
1123 Only affects "broken" chipsets. Interrupt sharing may be
1124 increased on these systems.
1127 bool "Machine Check / overheating reporting"
1128 select GENERIC_ALLOCATOR
1131 Machine Check support allows the processor to notify the
1132 kernel if it detects a problem (e.g. overheating, data corruption).
1133 The action the kernel takes depends on the severity of the problem,
1134 ranging from warning messages to halting the machine.
1136 config X86_MCELOG_LEGACY
1137 bool "Support for deprecated /dev/mcelog character device"
1140 Enable support for /dev/mcelog which is needed by the old mcelog
1141 userspace logging daemon. Consider switching to the new generation
1144 config X86_MCE_INTEL
1146 prompt "Intel MCE features"
1147 depends on X86_MCE && X86_LOCAL_APIC
1149 Additional support for intel specific MCE features such as
1150 the thermal monitor.
1154 prompt "AMD MCE features"
1155 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1157 Additional support for AMD specific MCE features such as
1158 the DRAM Error Threshold.
1160 config X86_ANCIENT_MCE
1161 bool "Support for old Pentium 5 / WinChip machine checks"
1162 depends on X86_32 && X86_MCE
1164 Include support for machine check handling on old Pentium 5 or WinChip
1165 systems. These typically need to be enabled explicitly on the command
1168 config X86_MCE_THRESHOLD
1169 depends on X86_MCE_AMD || X86_MCE_INTEL
1172 config X86_MCE_INJECT
1173 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1174 tristate "Machine check injector support"
1176 Provide support for injecting machine checks for testing purposes.
1177 If you don't know what a machine check is and you don't do kernel
1178 QA it is safe to say n.
1180 source "arch/x86/events/Kconfig"
1182 config X86_LEGACY_VM86
1183 bool "Legacy VM86 support"
1186 This option allows user programs to put the CPU into V8086
1187 mode, which is an 80286-era approximation of 16-bit real mode.
1189 Some very old versions of X and/or vbetool require this option
1190 for user mode setting. Similarly, DOSEMU will use it if
1191 available to accelerate real mode DOS programs. However, any
1192 recent version of DOSEMU, X, or vbetool should be fully
1193 functional even without kernel VM86 support, as they will all
1194 fall back to software emulation. Nevertheless, if you are using
1195 a 16-bit DOS program where 16-bit performance matters, vm86
1196 mode might be faster than emulation and you might want to
1199 Note that any app that works on a 64-bit kernel is unlikely to
1200 need this option, as 64-bit kernels don't, and can't, support
1201 V8086 mode. This option is also unrelated to 16-bit protected
1202 mode and is not needed to run most 16-bit programs under Wine.
1204 Enabling this option increases the complexity of the kernel
1205 and slows down exception handling a tiny bit.
1207 If unsure, say N here.
1211 default X86_LEGACY_VM86
1214 bool "Enable support for 16-bit segments" if EXPERT
1216 depends on MODIFY_LDT_SYSCALL
1218 This option is required by programs like Wine to run 16-bit
1219 protected mode legacy code on x86 processors. Disabling
1220 this option saves about 300 bytes on i386, or around 6K text
1221 plus 16K runtime memory on x86-64,
1225 depends on X86_16BIT && X86_32
1229 depends on X86_16BIT && X86_64
1231 config X86_VSYSCALL_EMULATION
1232 bool "Enable vsyscall emulation" if EXPERT
1236 This enables emulation of the legacy vsyscall page. Disabling
1237 it is roughly equivalent to booting with vsyscall=none, except
1238 that it will also disable the helpful warning if a program
1239 tries to use a vsyscall. With this option set to N, offending
1240 programs will just segfault, citing addresses of the form
1243 This option is required by many programs built before 2013, and
1244 care should be used even with newer programs if set to N.
1246 Disabling this option saves about 7K of kernel size and
1247 possibly 4K of additional runtime pagetable memory.
1249 config X86_IOPL_IOPERM
1250 bool "IOPERM and IOPL Emulation"
1253 This enables the ioperm() and iopl() syscalls which are necessary
1254 for legacy applications.
1256 Legacy IOPL support is an overbroad mechanism which allows user
1257 space aside of accessing all 65536 I/O ports also to disable
1258 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1259 capabilities and permission from potentially active security
1262 The emulation restricts the functionality of the syscall to
1263 only allowing the full range I/O port access, but prevents the
1264 ability to disable interrupts from user space which would be
1265 granted if the hardware IOPL mechanism would be used.
1268 tristate "Toshiba Laptop support"
1271 This adds a driver to safely access the System Management Mode of
1272 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1273 not work on models with a Phoenix BIOS. The System Management Mode
1274 is used to set the BIOS and power saving options on Toshiba portables.
1276 For information on utilities to make use of this driver see the
1277 Toshiba Linux utilities web site at:
1278 <http://www.buzzard.org.uk/toshiba/>.
1280 Say Y if you intend to run this kernel on a Toshiba portable.
1283 config X86_REBOOTFIXUPS
1284 bool "Enable X86 board specific fixups for reboot"
1287 This enables chipset and/or board specific fixups to be done
1288 in order to get reboot to work correctly. This is only needed on
1289 some combinations of hardware and BIOS. The symptom, for which
1290 this config is intended, is when reboot ends with a stalled/hung
1293 Currently, the only fixup is for the Geode machines using
1294 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1296 Say Y if you want to enable the fixup. Currently, it's safe to
1297 enable this option even if you don't need it.
1301 bool "CPU microcode loading support"
1303 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1305 If you say Y here, you will be able to update the microcode on
1306 Intel and AMD processors. The Intel support is for the IA32 family,
1307 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1308 AMD support is for families 0x10 and later. You will obviously need
1309 the actual microcode binary data itself which is not shipped with
1312 The preferred method to load microcode from a detached initrd is described
1313 in Documentation/x86/microcode.rst. For that you need to enable
1314 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1315 initrd for microcode blobs.
1317 In addition, you can build the microcode into the kernel. For that you
1318 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1321 config MICROCODE_INTEL
1322 bool "Intel microcode loading support"
1323 depends on CPU_SUP_INTEL && MICROCODE
1326 This options enables microcode patch loading support for Intel
1329 For the current Intel microcode data package go to
1330 <https://downloadcenter.intel.com> and search for
1331 'Linux Processor Microcode Data File'.
1333 config MICROCODE_AMD
1334 bool "AMD microcode loading support"
1335 depends on CPU_SUP_AMD && MICROCODE
1337 If you select this option, microcode patch loading support for AMD
1338 processors will be enabled.
1340 config MICROCODE_LATE_LOADING
1341 bool "Late microcode loading (DANGEROUS)"
1343 depends on MICROCODE
1345 Loading microcode late, when the system is up and executing instructions
1346 is a tricky business and should be avoided if possible. Just the sequence
1347 of synchronizing all cores and SMT threads is one fragile dance which does
1348 not guarantee that cores might not softlock after the loading. Therefore,
1349 use this at your own risk. Late loading taints the kernel too.
1352 tristate "/dev/cpu/*/msr - Model-specific register support"
1354 This device gives privileged processes access to the x86
1355 Model-Specific Registers (MSRs). It is a character device with
1356 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1357 MSR accesses are directed to a specific CPU on multi-processor
1361 tristate "/dev/cpu/*/cpuid - CPU information support"
1363 This device gives processes access to the x86 CPUID instruction to
1364 be executed on a specific processor. It is a character device
1365 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1369 prompt "High Memory Support"
1376 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1377 However, the address space of 32-bit x86 processors is only 4
1378 Gigabytes large. That means that, if you have a large amount of
1379 physical memory, not all of it can be "permanently mapped" by the
1380 kernel. The physical memory that's not permanently mapped is called
1383 If you are compiling a kernel which will never run on a machine with
1384 more than 1 Gigabyte total physical RAM, answer "off" here (default
1385 choice and suitable for most users). This will result in a "3GB/1GB"
1386 split: 3GB are mapped so that each process sees a 3GB virtual memory
1387 space and the remaining part of the 4GB virtual memory space is used
1388 by the kernel to permanently map as much physical memory as
1391 If the machine has between 1 and 4 Gigabytes physical RAM, then
1394 If more than 4 Gigabytes is used then answer "64GB" here. This
1395 selection turns Intel PAE (Physical Address Extension) mode on.
1396 PAE implements 3-level paging on IA32 processors. PAE is fully
1397 supported by Linux, PAE mode is implemented on all recent Intel
1398 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1399 then the kernel will not boot on CPUs that don't support PAE!
1401 The actual amount of total physical memory will either be
1402 auto detected or can be forced by using a kernel command line option
1403 such as "mem=256M". (Try "man bootparam" or see the documentation of
1404 your boot loader (lilo or loadlin) about how to pass options to the
1405 kernel at boot time.)
1407 If unsure, say "off".
1412 Select this if you have a 32-bit processor and between 1 and 4
1413 gigabytes of physical RAM.
1417 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1420 Select this if you have a 32-bit processor and more than 4
1421 gigabytes of physical RAM.
1426 prompt "Memory split" if EXPERT
1430 Select the desired split between kernel and user memory.
1432 If the address range available to the kernel is less than the
1433 physical memory installed, the remaining memory will be available
1434 as "high memory". Accessing high memory is a little more costly
1435 than low memory, as it needs to be mapped into the kernel first.
1436 Note that increasing the kernel address space limits the range
1437 available to user programs, making the address space there
1438 tighter. Selecting anything other than the default 3G/1G split
1439 will also likely make your kernel incompatible with binary-only
1442 If you are not absolutely sure what you are doing, leave this
1446 bool "3G/1G user/kernel split"
1447 config VMSPLIT_3G_OPT
1449 bool "3G/1G user/kernel split (for full 1G low memory)"
1451 bool "2G/2G user/kernel split"
1452 config VMSPLIT_2G_OPT
1454 bool "2G/2G user/kernel split (for full 2G low memory)"
1456 bool "1G/3G user/kernel split"
1461 default 0xB0000000 if VMSPLIT_3G_OPT
1462 default 0x80000000 if VMSPLIT_2G
1463 default 0x78000000 if VMSPLIT_2G_OPT
1464 default 0x40000000 if VMSPLIT_1G
1470 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1473 bool "PAE (Physical Address Extension) Support"
1474 depends on X86_32 && !HIGHMEM4G
1475 select PHYS_ADDR_T_64BIT
1478 PAE is required for NX support, and furthermore enables
1479 larger swapspace support for non-overcommit purposes. It
1480 has the cost of more pagetable lookup overhead, and also
1481 consumes more pagetable space per process.
1484 bool "Enable 5-level page tables support"
1486 select DYNAMIC_MEMORY_LAYOUT
1487 select SPARSEMEM_VMEMMAP
1490 5-level paging enables access to larger address space:
1491 upto 128 PiB of virtual address space and 4 PiB of
1492 physical address space.
1494 It will be supported by future Intel CPUs.
1496 A kernel with the option enabled can be booted on machines that
1497 support 4- or 5-level paging.
1499 See Documentation/x86/x86_64/5level-paging.rst for more
1504 config X86_DIRECT_GBPAGES
1508 Certain kernel features effectively disable kernel
1509 linear 1 GB mappings (even if the CPU otherwise
1510 supports them), so don't confuse the user by printing
1511 that we have them enabled.
1513 config X86_CPA_STATISTICS
1514 bool "Enable statistic for Change Page Attribute"
1517 Expose statistics about the Change Page Attribute mechanism, which
1518 helps to determine the effectiveness of preserving large and huge
1519 page mappings when mapping protections are changed.
1521 config X86_MEM_ENCRYPT
1522 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1523 select DYNAMIC_PHYSICAL_MASK
1526 config AMD_MEM_ENCRYPT
1527 bool "AMD Secure Memory Encryption (SME) support"
1528 depends on X86_64 && CPU_SUP_AMD
1529 select DMA_COHERENT_POOL
1530 select ARCH_USE_MEMREMAP_PROT
1531 select INSTRUCTION_DECODER
1532 select ARCH_HAS_CC_PLATFORM
1533 select X86_MEM_ENCRYPT
1535 Say yes to enable support for the encryption of system memory.
1536 This requires an AMD processor that supports Secure Memory
1539 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1540 bool "Activate AMD Secure Memory Encryption (SME) by default"
1541 depends on AMD_MEM_ENCRYPT
1543 Say yes to have system memory encrypted by default if running on
1544 an AMD processor that supports Secure Memory Encryption (SME).
1546 If set to Y, then the encryption of system memory can be
1547 deactivated with the mem_encrypt=off command line option.
1549 If set to N, then the encryption of system memory can be
1550 activated with the mem_encrypt=on command line option.
1552 # Common NUMA Features
1554 bool "NUMA Memory Allocation and Scheduler Support"
1556 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1557 default y if X86_BIGSMP
1558 select USE_PERCPU_NUMA_NODE_ID
1560 Enable NUMA (Non-Uniform Memory Access) support.
1562 The kernel will try to allocate memory used by a CPU on the
1563 local memory controller of the CPU and add some more
1564 NUMA awareness to the kernel.
1566 For 64-bit this is recommended if the system is Intel Core i7
1567 (or later), AMD Opteron, or EM64T NUMA.
1569 For 32-bit this is only needed if you boot a 32-bit
1570 kernel on a 64-bit NUMA platform.
1572 Otherwise, you should say N.
1576 prompt "Old style AMD Opteron NUMA detection"
1577 depends on X86_64 && NUMA && PCI
1579 Enable AMD NUMA node topology detection. You should say Y here if
1580 you have a multi processor AMD system. This uses an old method to
1581 read the NUMA configuration directly from the builtin Northbridge
1582 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1583 which also takes priority if both are compiled in.
1585 config X86_64_ACPI_NUMA
1587 prompt "ACPI NUMA detection"
1588 depends on X86_64 && NUMA && ACPI && PCI
1591 Enable ACPI SRAT based node topology detection.
1594 bool "NUMA emulation"
1597 Enable NUMA emulation. A flat machine will be split
1598 into virtual nodes when booted with "numa=fake=N", where N is the
1599 number of nodes. This is only useful for debugging.
1602 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1604 default "10" if MAXSMP
1605 default "6" if X86_64
1609 Specify the maximum number of NUMA Nodes available on the target
1610 system. Increases memory reserved to accommodate various tables.
1612 config ARCH_FLATMEM_ENABLE
1614 depends on X86_32 && !NUMA
1616 config ARCH_SPARSEMEM_ENABLE
1618 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1619 select SPARSEMEM_STATIC if X86_32
1620 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1622 config ARCH_SPARSEMEM_DEFAULT
1623 def_bool X86_64 || (NUMA && X86_32)
1625 config ARCH_SELECT_MEMORY_MODEL
1627 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1629 config ARCH_MEMORY_PROBE
1630 bool "Enable sysfs memory/probe interface"
1631 depends on MEMORY_HOTPLUG
1633 This option enables a sysfs memory/probe interface for testing.
1634 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1635 If you are unsure how to answer this question, answer N.
1637 config ARCH_PROC_KCORE_TEXT
1639 depends on X86_64 && PROC_KCORE
1641 config ILLEGAL_POINTER_VALUE
1644 default 0xdead000000000000 if X86_64
1646 config X86_PMEM_LEGACY_DEVICE
1649 config X86_PMEM_LEGACY
1650 tristate "Support non-standard NVDIMMs and ADR protected memory"
1651 depends on PHYS_ADDR_T_64BIT
1653 select X86_PMEM_LEGACY_DEVICE
1654 select NUMA_KEEP_MEMINFO if NUMA
1657 Treat memory marked using the non-standard e820 type of 12 as used
1658 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1659 The kernel will offer these regions to the 'pmem' driver so
1660 they can be used for persistent storage.
1665 bool "Allocate 3rd-level pagetables from highmem"
1668 The VM uses one page table entry for each page of physical memory.
1669 For systems with a lot of RAM, this can be wasteful of precious
1670 low memory. Setting this option will put user-space page table
1671 entries in high memory.
1673 config X86_CHECK_BIOS_CORRUPTION
1674 bool "Check for low memory corruption"
1676 Periodically check for memory corruption in low memory, which
1677 is suspected to be caused by BIOS. Even when enabled in the
1678 configuration, it is disabled at runtime. Enable it by
1679 setting "memory_corruption_check=1" on the kernel command
1680 line. By default it scans the low 64k of memory every 60
1681 seconds; see the memory_corruption_check_size and
1682 memory_corruption_check_period parameters in
1683 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1685 When enabled with the default parameters, this option has
1686 almost no overhead, as it reserves a relatively small amount
1687 of memory and scans it infrequently. It both detects corruption
1688 and prevents it from affecting the running system.
1690 It is, however, intended as a diagnostic tool; if repeatable
1691 BIOS-originated corruption always affects the same memory,
1692 you can use memmap= to prevent the kernel from using that
1695 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1696 bool "Set the default setting of memory_corruption_check"
1697 depends on X86_CHECK_BIOS_CORRUPTION
1700 Set whether the default state of memory_corruption_check is
1703 config MATH_EMULATION
1705 depends on MODIFY_LDT_SYSCALL
1706 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1708 Linux can emulate a math coprocessor (used for floating point
1709 operations) if you don't have one. 486DX and Pentium processors have
1710 a math coprocessor built in, 486SX and 386 do not, unless you added
1711 a 487DX or 387, respectively. (The messages during boot time can
1712 give you some hints here ["man dmesg"].) Everyone needs either a
1713 coprocessor or this emulation.
1715 If you don't have a math coprocessor, you need to say Y here; if you
1716 say Y here even though you have a coprocessor, the coprocessor will
1717 be used nevertheless. (This behavior can be changed with the kernel
1718 command line option "no387", which comes handy if your coprocessor
1719 is broken. Try "man bootparam" or see the documentation of your boot
1720 loader (lilo or loadlin) about how to pass options to the kernel at
1721 boot time.) This means that it is a good idea to say Y here if you
1722 intend to use this kernel on different machines.
1724 More information about the internals of the Linux math coprocessor
1725 emulation can be found in <file:arch/x86/math-emu/README>.
1727 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1728 kernel, it won't hurt.
1732 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1734 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1735 the Memory Type Range Registers (MTRRs) may be used to control
1736 processor access to memory ranges. This is most useful if you have
1737 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1738 allows bus write transfers to be combined into a larger transfer
1739 before bursting over the PCI/AGP bus. This can increase performance
1740 of image write operations 2.5 times or more. Saying Y here creates a
1741 /proc/mtrr file which may be used to manipulate your processor's
1742 MTRRs. Typically the X server should use this.
1744 This code has a reasonably generic interface so that similar
1745 control registers on other processors can be easily supported
1748 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1749 Registers (ARRs) which provide a similar functionality to MTRRs. For
1750 these, the ARRs are used to emulate the MTRRs.
1751 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1752 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1753 write-combining. All of these processors are supported by this code
1754 and it makes sense to say Y here if you have one of them.
1756 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1757 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1758 can lead to all sorts of problems, so it's good to say Y here.
1760 You can safely say Y even if your machine doesn't have MTRRs, you'll
1761 just add about 9 KB to your kernel.
1763 See <file:Documentation/x86/mtrr.rst> for more information.
1765 config MTRR_SANITIZER
1767 prompt "MTRR cleanup support"
1770 Convert MTRR layout from continuous to discrete, so X drivers can
1771 add writeback entries.
1773 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1774 The largest mtrr entry size for a continuous block can be set with
1779 config MTRR_SANITIZER_ENABLE_DEFAULT
1780 int "MTRR cleanup enable value (0-1)"
1783 depends on MTRR_SANITIZER
1785 Enable mtrr cleanup default value
1787 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1788 int "MTRR cleanup spare reg num (0-7)"
1791 depends on MTRR_SANITIZER
1793 mtrr cleanup spare entries default, it can be changed via
1794 mtrr_spare_reg_nr=N on the kernel command line.
1798 prompt "x86 PAT support" if EXPERT
1801 Use PAT attributes to setup page level cache control.
1803 PATs are the modern equivalents of MTRRs and are much more
1804 flexible than MTRRs.
1806 Say N here if you see bootup problems (boot crash, boot hang,
1807 spontaneous reboots) or a non-working video driver.
1811 config ARCH_USES_PG_UNCACHED
1817 prompt "User Mode Instruction Prevention" if EXPERT
1819 User Mode Instruction Prevention (UMIP) is a security feature in
1820 some x86 processors. If enabled, a general protection fault is
1821 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1822 executed in user mode. These instructions unnecessarily expose
1823 information about the hardware state.
1825 The vast majority of applications do not use these instructions.
1826 For the very few that do, software emulation is provided in
1827 specific cases in protected and virtual-8086 modes. Emulated
1831 # GCC >= 9 and binutils >= 2.29
1832 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1834 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1835 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1836 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1837 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1840 config X86_KERNEL_IBT
1841 prompt "Indirect Branch Tracking"
1843 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1844 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1845 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1848 Build the kernel with support for Indirect Branch Tracking, a
1849 hardware support course-grain forward-edge Control Flow Integrity
1850 protection. It enforces that all indirect calls must land on
1851 an ENDBR instruction, as such, the compiler will instrument the
1852 code with them to make this happen.
1854 In addition to building the kernel with IBT, seal all functions that
1855 are not indirect call targets, avoiding them ever becoming one.
1857 This requires LTO like objtool runs and will slow down the build. It
1858 does significantly reduce the number of ENDBR instructions in the
1861 config X86_INTEL_MEMORY_PROTECTION_KEYS
1862 prompt "Memory Protection Keys"
1864 # Note: only available in 64-bit mode
1865 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1866 select ARCH_USES_HIGH_VMA_FLAGS
1867 select ARCH_HAS_PKEYS
1869 Memory Protection Keys provides a mechanism for enforcing
1870 page-based protections, but without requiring modification of the
1871 page tables when an application changes protection domains.
1873 For details, see Documentation/core-api/protection-keys.rst
1878 prompt "TSX enable mode"
1879 depends on CPU_SUP_INTEL
1880 default X86_INTEL_TSX_MODE_OFF
1882 Intel's TSX (Transactional Synchronization Extensions) feature
1883 allows to optimize locking protocols through lock elision which
1884 can lead to a noticeable performance boost.
1886 On the other hand it has been shown that TSX can be exploited
1887 to form side channel attacks (e.g. TAA) and chances are there
1888 will be more of those attacks discovered in the future.
1890 Therefore TSX is not enabled by default (aka tsx=off). An admin
1891 might override this decision by tsx=on the command line parameter.
1892 Even with TSX enabled, the kernel will attempt to enable the best
1893 possible TAA mitigation setting depending on the microcode available
1894 for the particular machine.
1896 This option allows to set the default tsx mode between tsx=on, =off
1897 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1900 Say off if not sure, auto if TSX is in use but it should be used on safe
1901 platforms or on if TSX is in use and the security aspect of tsx is not
1904 config X86_INTEL_TSX_MODE_OFF
1907 TSX is disabled if possible - equals to tsx=off command line parameter.
1909 config X86_INTEL_TSX_MODE_ON
1912 TSX is always enabled on TSX capable HW - equals the tsx=on command
1915 config X86_INTEL_TSX_MODE_AUTO
1918 TSX is enabled on TSX capable HW that is believed to be safe against
1919 side channel attacks- equals the tsx=auto command line parameter.
1923 bool "Software Guard eXtensions (SGX)"
1924 depends on X86_64 && CPU_SUP_INTEL
1926 depends on CRYPTO_SHA256=y
1929 select NUMA_KEEP_MEMINFO if NUMA
1932 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1933 that can be used by applications to set aside private regions of code
1934 and data, referred to as enclaves. An enclave's private memory can
1935 only be accessed by code running within the enclave. Accesses from
1936 outside the enclave, including other enclaves, are disallowed by
1942 bool "EFI runtime service support"
1945 select EFI_RUNTIME_WRAPPERS
1946 select ARCH_USE_MEMREMAP_PROT
1948 This enables the kernel to use EFI runtime services that are
1949 available (such as the EFI variable services).
1951 This option is only useful on systems that have EFI firmware.
1952 In addition, you should use the latest ELILO loader available
1953 at <http://elilo.sourceforge.net> in order to take advantage
1954 of EFI runtime services. However, even with this option, the
1955 resultant kernel should continue to boot on existing non-EFI
1959 bool "EFI stub support"
1961 depends on $(cc-option,-mabi=ms) || X86_32
1964 This kernel feature allows a bzImage to be loaded directly
1965 by EFI firmware without the use of a bootloader.
1967 See Documentation/admin-guide/efi-stub.rst for more information.
1970 bool "EFI mixed-mode support"
1971 depends on EFI_STUB && X86_64
1973 Enabling this feature allows a 64-bit kernel to be booted
1974 on a 32-bit firmware, provided that your CPU supports 64-bit
1977 Note that it is not possible to boot a mixed-mode enabled
1978 kernel via the EFI boot stub - a bootloader that supports
1979 the EFI handover protocol must be used.
1983 source "kernel/Kconfig.hz"
1986 bool "kexec system call"
1989 kexec is a system call that implements the ability to shutdown your
1990 current kernel, and to start another kernel. It is like a reboot
1991 but it is independent of the system firmware. And like a reboot
1992 you can start any kernel with it, not just Linux.
1994 The name comes from the similarity to the exec system call.
1996 It is an ongoing process to be certain the hardware in a machine
1997 is properly shutdown, so do not be surprised if this code does not
1998 initially work for you. As of this writing the exact hardware
1999 interface is strongly in flux, so no good recommendation can be
2003 bool "kexec file based system call"
2005 select HAVE_IMA_KEXEC if IMA
2008 depends on CRYPTO_SHA256=y
2010 This is new version of kexec system call. This system call is
2011 file based and takes file descriptors as system call argument
2012 for kernel and initramfs as opposed to list of segments as
2013 accepted by previous system call.
2015 config ARCH_HAS_KEXEC_PURGATORY
2019 bool "Verify kernel signature during kexec_file_load() syscall"
2020 depends on KEXEC_FILE
2023 This option makes the kexec_file_load() syscall check for a valid
2024 signature of the kernel image. The image can still be loaded without
2025 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2026 there's a signature that we can check, then it must be valid.
2028 In addition to this option, you need to enable signature
2029 verification for the corresponding kernel image type being
2030 loaded in order for this to work.
2032 config KEXEC_SIG_FORCE
2033 bool "Require a valid signature in kexec_file_load() syscall"
2034 depends on KEXEC_SIG
2036 This option makes kernel signature verification mandatory for
2037 the kexec_file_load() syscall.
2039 config KEXEC_BZIMAGE_VERIFY_SIG
2040 bool "Enable bzImage signature verification support"
2041 depends on KEXEC_SIG
2042 depends on SIGNED_PE_FILE_VERIFICATION
2043 select SYSTEM_TRUSTED_KEYRING
2045 Enable bzImage signature verification support.
2048 bool "kernel crash dumps"
2049 depends on X86_64 || (X86_32 && HIGHMEM)
2051 Generate crash dump after being started by kexec.
2052 This should be normally only set in special crash dump kernels
2053 which are loaded in the main kernel with kexec-tools into
2054 a specially reserved region and then later executed after
2055 a crash by kdump/kexec. The crash dump kernel must be compiled
2056 to a memory address not used by the main kernel or BIOS using
2057 PHYSICAL_START, or it must be built as a relocatable image
2058 (CONFIG_RELOCATABLE=y).
2059 For more details see Documentation/admin-guide/kdump/kdump.rst
2063 depends on KEXEC && HIBERNATION
2065 Jump between original kernel and kexeced kernel and invoke
2066 code in physical address mode via KEXEC
2068 config PHYSICAL_START
2069 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2072 This gives the physical address where the kernel is loaded.
2074 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2075 bzImage will decompress itself to above physical address and
2076 run from there. Otherwise, bzImage will run from the address where
2077 it has been loaded by the boot loader and will ignore above physical
2080 In normal kdump cases one does not have to set/change this option
2081 as now bzImage can be compiled as a completely relocatable image
2082 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2083 address. This option is mainly useful for the folks who don't want
2084 to use a bzImage for capturing the crash dump and want to use a
2085 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2086 to be specifically compiled to run from a specific memory area
2087 (normally a reserved region) and this option comes handy.
2089 So if you are using bzImage for capturing the crash dump,
2090 leave the value here unchanged to 0x1000000 and set
2091 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2092 for capturing the crash dump change this value to start of
2093 the reserved region. In other words, it can be set based on
2094 the "X" value as specified in the "crashkernel=YM@XM"
2095 command line boot parameter passed to the panic-ed
2096 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2097 for more details about crash dumps.
2099 Usage of bzImage for capturing the crash dump is recommended as
2100 one does not have to build two kernels. Same kernel can be used
2101 as production kernel and capture kernel. Above option should have
2102 gone away after relocatable bzImage support is introduced. But it
2103 is present because there are users out there who continue to use
2104 vmlinux for dump capture. This option should go away down the
2107 Don't change this unless you know what you are doing.
2110 bool "Build a relocatable kernel"
2113 This builds a kernel image that retains relocation information
2114 so it can be loaded someplace besides the default 1MB.
2115 The relocations tend to make the kernel binary about 10% larger,
2116 but are discarded at runtime.
2118 One use is for the kexec on panic case where the recovery kernel
2119 must live at a different physical address than the primary
2122 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2123 it has been loaded at and the compile time physical address
2124 (CONFIG_PHYSICAL_START) is used as the minimum location.
2126 config RANDOMIZE_BASE
2127 bool "Randomize the address of the kernel image (KASLR)"
2128 depends on RELOCATABLE
2131 In support of Kernel Address Space Layout Randomization (KASLR),
2132 this randomizes the physical address at which the kernel image
2133 is decompressed and the virtual address where the kernel
2134 image is mapped, as a security feature that deters exploit
2135 attempts relying on knowledge of the location of kernel
2138 On 64-bit, the kernel physical and virtual addresses are
2139 randomized separately. The physical address will be anywhere
2140 between 16MB and the top of physical memory (up to 64TB). The
2141 virtual address will be randomized from 16MB up to 1GB (9 bits
2142 of entropy). Note that this also reduces the memory space
2143 available to kernel modules from 1.5GB to 1GB.
2145 On 32-bit, the kernel physical and virtual addresses are
2146 randomized together. They will be randomized from 16MB up to
2147 512MB (8 bits of entropy).
2149 Entropy is generated using the RDRAND instruction if it is
2150 supported. If RDTSC is supported, its value is mixed into
2151 the entropy pool as well. If neither RDRAND nor RDTSC are
2152 supported, then entropy is read from the i8254 timer. The
2153 usable entropy is limited by the kernel being built using
2154 2GB addressing, and that PHYSICAL_ALIGN must be at a
2155 minimum of 2MB. As a result, only 10 bits of entropy are
2156 theoretically possible, but the implementations are further
2157 limited due to memory layouts.
2161 # Relocation on x86 needs some additional build support
2162 config X86_NEED_RELOCS
2164 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2166 config PHYSICAL_ALIGN
2167 hex "Alignment value to which kernel should be aligned"
2169 range 0x2000 0x1000000 if X86_32
2170 range 0x200000 0x1000000 if X86_64
2172 This value puts the alignment restrictions on physical address
2173 where kernel is loaded and run from. Kernel is compiled for an
2174 address which meets above alignment restriction.
2176 If bootloader loads the kernel at a non-aligned address and
2177 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2178 address aligned to above value and run from there.
2180 If bootloader loads the kernel at a non-aligned address and
2181 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2182 load address and decompress itself to the address it has been
2183 compiled for and run from there. The address for which kernel is
2184 compiled already meets above alignment restrictions. Hence the
2185 end result is that kernel runs from a physical address meeting
2186 above alignment restrictions.
2188 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2189 this value must be a multiple of 0x200000.
2191 Don't change this unless you know what you are doing.
2193 config DYNAMIC_MEMORY_LAYOUT
2196 This option makes base addresses of vmalloc and vmemmap as well as
2197 __PAGE_OFFSET movable during boot.
2199 config RANDOMIZE_MEMORY
2200 bool "Randomize the kernel memory sections"
2202 depends on RANDOMIZE_BASE
2203 select DYNAMIC_MEMORY_LAYOUT
2204 default RANDOMIZE_BASE
2206 Randomizes the base virtual address of kernel memory sections
2207 (physical memory mapping, vmalloc & vmemmap). This security feature
2208 makes exploits relying on predictable memory locations less reliable.
2210 The order of allocations remains unchanged. Entropy is generated in
2211 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2212 configuration have in average 30,000 different possible virtual
2213 addresses for each memory section.
2217 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2218 hex "Physical memory mapping padding" if EXPERT
2219 depends on RANDOMIZE_MEMORY
2220 default "0xa" if MEMORY_HOTPLUG
2222 range 0x1 0x40 if MEMORY_HOTPLUG
2225 Define the padding in terabytes added to the existing physical
2226 memory size during kernel memory randomization. It is useful
2227 for memory hotplug support but reduces the entropy available for
2228 address randomization.
2230 If unsure, leave at the default value.
2236 config BOOTPARAM_HOTPLUG_CPU0
2237 bool "Set default setting of cpu0_hotpluggable"
2238 depends on HOTPLUG_CPU
2240 Set whether default state of cpu0_hotpluggable is on or off.
2242 Say Y here to enable CPU0 hotplug by default. If this switch
2243 is turned on, there is no need to give cpu0_hotplug kernel
2244 parameter and the CPU0 hotplug feature is enabled by default.
2246 Please note: there are two known CPU0 dependencies if you want
2247 to enable the CPU0 hotplug feature either by this switch or by
2248 cpu0_hotplug kernel parameter.
2250 First, resume from hibernate or suspend always starts from CPU0.
2251 So hibernate and suspend are prevented if CPU0 is offline.
2253 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2254 offline if any interrupt can not migrate out of CPU0. There may
2255 be other CPU0 dependencies.
2257 Please make sure the dependencies are under your control before
2258 you enable this feature.
2260 Say N if you don't want to enable CPU0 hotplug feature by default.
2261 You still can enable the CPU0 hotplug feature at boot by kernel
2262 parameter cpu0_hotplug.
2264 config DEBUG_HOTPLUG_CPU0
2266 prompt "Debug CPU0 hotplug"
2267 depends on HOTPLUG_CPU
2269 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2270 soon as possible and boots up userspace with CPU0 offlined. User
2271 can online CPU0 back after boot time.
2273 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2274 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2275 compilation or giving cpu0_hotplug kernel parameter at boot.
2281 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2282 depends on COMPAT_32
2284 Certain buggy versions of glibc will crash if they are
2285 presented with a 32-bit vDSO that is not mapped at the address
2286 indicated in its segment table.
2288 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2289 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2290 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2291 the only released version with the bug, but OpenSUSE 9
2292 contains a buggy "glibc 2.3.2".
2294 The symptom of the bug is that everything crashes on startup, saying:
2295 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2297 Saying Y here changes the default value of the vdso32 boot
2298 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2299 This works around the glibc bug but hurts performance.
2301 If unsure, say N: if you are compiling your own kernel, you
2302 are unlikely to be using a buggy version of glibc.
2305 prompt "vsyscall table for legacy applications"
2307 default LEGACY_VSYSCALL_XONLY
2309 Legacy user code that does not know how to find the vDSO expects
2310 to be able to issue three syscalls by calling fixed addresses in
2311 kernel space. Since this location is not randomized with ASLR,
2312 it can be used to assist security vulnerability exploitation.
2314 This setting can be changed at boot time via the kernel command
2315 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2316 is deprecated and can only be enabled using the kernel command
2319 On a system with recent enough glibc (2.14 or newer) and no
2320 static binaries, you can say None without a performance penalty
2321 to improve security.
2323 If unsure, select "Emulate execution only".
2325 config LEGACY_VSYSCALL_XONLY
2326 bool "Emulate execution only"
2328 The kernel traps and emulates calls into the fixed vsyscall
2329 address mapping and does not allow reads. This
2330 configuration is recommended when userspace might use the
2331 legacy vsyscall area but support for legacy binary
2332 instrumentation of legacy code is not needed. It mitigates
2333 certain uses of the vsyscall area as an ASLR-bypassing
2336 config LEGACY_VSYSCALL_NONE
2339 There will be no vsyscall mapping at all. This will
2340 eliminate any risk of ASLR bypass due to the vsyscall
2341 fixed address mapping. Attempts to use the vsyscalls
2342 will be reported to dmesg, so that either old or
2343 malicious userspace programs can be identified.
2348 bool "Built-in kernel command line"
2350 Allow for specifying boot arguments to the kernel at
2351 build time. On some systems (e.g. embedded ones), it is
2352 necessary or convenient to provide some or all of the
2353 kernel boot arguments with the kernel itself (that is,
2354 to not rely on the boot loader to provide them.)
2356 To compile command line arguments into the kernel,
2357 set this option to 'Y', then fill in the
2358 boot arguments in CONFIG_CMDLINE.
2360 Systems with fully functional boot loaders (i.e. non-embedded)
2361 should leave this option set to 'N'.
2364 string "Built-in kernel command string"
2365 depends on CMDLINE_BOOL
2368 Enter arguments here that should be compiled into the kernel
2369 image and used at boot time. If the boot loader provides a
2370 command line at boot time, it is appended to this string to
2371 form the full kernel command line, when the system boots.
2373 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2374 change this behavior.
2376 In most cases, the command line (whether built-in or provided
2377 by the boot loader) should specify the device for the root
2380 config CMDLINE_OVERRIDE
2381 bool "Built-in command line overrides boot loader arguments"
2382 depends on CMDLINE_BOOL && CMDLINE != ""
2384 Set this option to 'Y' to have the kernel ignore the boot loader
2385 command line, and use ONLY the built-in command line.
2387 This is used to work around broken boot loaders. This should
2388 be set to 'N' under normal conditions.
2390 config MODIFY_LDT_SYSCALL
2391 bool "Enable the LDT (local descriptor table)" if EXPERT
2394 Linux can allow user programs to install a per-process x86
2395 Local Descriptor Table (LDT) using the modify_ldt(2) system
2396 call. This is required to run 16-bit or segmented code such as
2397 DOSEMU or some Wine programs. It is also used by some very old
2398 threading libraries.
2400 Enabling this feature adds a small amount of overhead to
2401 context switches and increases the low-level kernel attack
2402 surface. Disabling it removes the modify_ldt(2) system call.
2404 Saying 'N' here may make sense for embedded or server kernels.
2406 config STRICT_SIGALTSTACK_SIZE
2407 bool "Enforce strict size checking for sigaltstack"
2408 depends on DYNAMIC_SIGFRAME
2410 For historical reasons MINSIGSTKSZ is a constant which became
2411 already too small with AVX512 support. Add a mechanism to
2412 enforce strict checking of the sigaltstack size against the
2413 real size of the FPU frame. This option enables the check
2414 by default. It can also be controlled via the kernel command
2415 line option 'strict_sas_size' independent of this config
2416 switch. Enabling it might break existing applications which
2417 allocate a too small sigaltstack but 'work' because they
2418 never get a signal delivered.
2420 Say 'N' unless you want to really enforce this check.
2422 source "kernel/livepatch/Kconfig"
2427 def_bool $(cc-option,-mharden-sls=all)
2429 config CC_HAS_RETURN_THUNK
2430 def_bool $(cc-option,-mfunction-return=thunk-extern)
2432 menuconfig SPECULATION_MITIGATIONS
2433 bool "Mitigations for speculative execution vulnerabilities"
2436 Say Y here to enable options which enable mitigations for
2437 speculative execution hardware vulnerabilities.
2439 If you say N, all mitigations will be disabled. You really
2440 should know what you are doing to say so.
2442 if SPECULATION_MITIGATIONS
2444 config PAGE_TABLE_ISOLATION
2445 bool "Remove the kernel mapping in user mode"
2447 depends on (X86_64 || X86_PAE)
2449 This feature reduces the number of hardware side channels by
2450 ensuring that the majority of kernel addresses are not mapped
2453 See Documentation/x86/pti.rst for more details.
2456 bool "Avoid speculative indirect branches in kernel"
2457 select OBJTOOL if HAVE_OBJTOOL
2460 Compile kernel with the retpoline compiler options to guard against
2461 kernel-to-user data leaks by avoiding speculative indirect
2462 branches. Requires a compiler with -mindirect-branch=thunk-extern
2463 support for full protection. The kernel may run slower.
2466 bool "Enable return-thunks"
2467 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2468 select OBJTOOL if HAVE_OBJTOOL
2471 Compile the kernel with the return-thunks compiler option to guard
2472 against kernel-to-user data leaks by avoiding return speculation.
2473 Requires a compiler with -mfunction-return=thunk-extern
2474 support for full protection. The kernel may run slower.
2476 config CPU_UNRET_ENTRY
2477 bool "Enable UNRET on kernel entry"
2478 depends on CPU_SUP_AMD && RETHUNK && X86_64
2481 Compile the kernel with support for the retbleed=unret mitigation.
2483 config CPU_IBPB_ENTRY
2484 bool "Enable IBPB on kernel entry"
2485 depends on CPU_SUP_AMD && X86_64
2488 Compile the kernel with support for the retbleed=ibpb mitigation.
2490 config CPU_IBRS_ENTRY
2491 bool "Enable IBRS on kernel entry"
2492 depends on CPU_SUP_INTEL && X86_64
2495 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2496 This mitigates both spectre_v2 and retbleed at great cost to
2500 bool "Mitigate Straight-Line-Speculation"
2501 depends on CC_HAS_SLS && X86_64
2502 select OBJTOOL if HAVE_OBJTOOL
2505 Compile the kernel with straight-line-speculation options to guard
2506 against straight line speculation. The kernel image might be slightly
2511 config ARCH_HAS_ADD_PAGES
2513 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2515 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2518 menu "Power management and ACPI options"
2520 config ARCH_HIBERNATION_HEADER
2522 depends on HIBERNATION
2524 source "kernel/power/Kconfig"
2526 source "drivers/acpi/Kconfig"
2533 tristate "APM (Advanced Power Management) BIOS support"
2534 depends on X86_32 && PM_SLEEP
2536 APM is a BIOS specification for saving power using several different
2537 techniques. This is mostly useful for battery powered laptops with
2538 APM compliant BIOSes. If you say Y here, the system time will be
2539 reset after a RESUME operation, the /proc/apm device will provide
2540 battery status information, and user-space programs will receive
2541 notification of APM "events" (e.g. battery status change).
2543 If you select "Y" here, you can disable actual use of the APM
2544 BIOS by passing the "apm=off" option to the kernel at boot time.
2546 Note that the APM support is almost completely disabled for
2547 machines with more than one CPU.
2549 In order to use APM, you will need supporting software. For location
2550 and more information, read <file:Documentation/power/apm-acpi.rst>
2551 and the Battery Powered Linux mini-HOWTO, available from
2552 <http://www.tldp.org/docs.html#howto>.
2554 This driver does not spin down disk drives (see the hdparm(8)
2555 manpage ("man 8 hdparm") for that), and it doesn't turn off
2556 VESA-compliant "green" monitors.
2558 This driver does not support the TI 4000M TravelMate and the ACER
2559 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2560 desktop machines also don't have compliant BIOSes, and this driver
2561 may cause those machines to panic during the boot phase.
2563 Generally, if you don't have a battery in your machine, there isn't
2564 much point in using this driver and you should say N. If you get
2565 random kernel OOPSes or reboots that don't seem to be related to
2566 anything, try disabling/enabling this option (or disabling/enabling
2569 Some other things you should try when experiencing seemingly random,
2572 1) make sure that you have enough swap space and that it is
2574 2) pass the "no-hlt" option to the kernel
2575 3) switch on floating point emulation in the kernel and pass
2576 the "no387" option to the kernel
2577 4) pass the "floppy=nodma" option to the kernel
2578 5) pass the "mem=4M" option to the kernel (thereby disabling
2579 all but the first 4 MB of RAM)
2580 6) make sure that the CPU is not over clocked.
2581 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2582 8) disable the cache from your BIOS settings
2583 9) install a fan for the video card or exchange video RAM
2584 10) install a better fan for the CPU
2585 11) exchange RAM chips
2586 12) exchange the motherboard.
2588 To compile this driver as a module, choose M here: the
2589 module will be called apm.
2593 config APM_IGNORE_USER_SUSPEND
2594 bool "Ignore USER SUSPEND"
2596 This option will ignore USER SUSPEND requests. On machines with a
2597 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2598 series notebooks, it is necessary to say Y because of a BIOS bug.
2600 config APM_DO_ENABLE
2601 bool "Enable PM at boot time"
2603 Enable APM features at boot time. From page 36 of the APM BIOS
2604 specification: "When disabled, the APM BIOS does not automatically
2605 power manage devices, enter the Standby State, enter the Suspend
2606 State, or take power saving steps in response to CPU Idle calls."
2607 This driver will make CPU Idle calls when Linux is idle (unless this
2608 feature is turned off -- see "Do CPU IDLE calls", below). This
2609 should always save battery power, but more complicated APM features
2610 will be dependent on your BIOS implementation. You may need to turn
2611 this option off if your computer hangs at boot time when using APM
2612 support, or if it beeps continuously instead of suspending. Turn
2613 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2614 T400CDT. This is off by default since most machines do fine without
2619 bool "Make CPU Idle calls when idle"
2621 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2622 On some machines, this can activate improved power savings, such as
2623 a slowed CPU clock rate, when the machine is idle. These idle calls
2624 are made after the idle loop has run for some length of time (e.g.,
2625 333 mS). On some machines, this will cause a hang at boot time or
2626 whenever the CPU becomes idle. (On machines with more than one CPU,
2627 this option does nothing.)
2629 config APM_DISPLAY_BLANK
2630 bool "Enable console blanking using APM"
2632 Enable console blanking using the APM. Some laptops can use this to
2633 turn off the LCD backlight when the screen blanker of the Linux
2634 virtual console blanks the screen. Note that this is only used by
2635 the virtual console screen blanker, and won't turn off the backlight
2636 when using the X Window system. This also doesn't have anything to
2637 do with your VESA-compliant power-saving monitor. Further, this
2638 option doesn't work for all laptops -- it might not turn off your
2639 backlight at all, or it might print a lot of errors to the console,
2640 especially if you are using gpm.
2642 config APM_ALLOW_INTS
2643 bool "Allow interrupts during APM BIOS calls"
2645 Normally we disable external interrupts while we are making calls to
2646 the APM BIOS as a measure to lessen the effects of a badly behaving
2647 BIOS implementation. The BIOS should reenable interrupts if it
2648 needs to. Unfortunately, some BIOSes do not -- especially those in
2649 many of the newer IBM Thinkpads. If you experience hangs when you
2650 suspend, try setting this to Y. Otherwise, say N.
2654 source "drivers/cpufreq/Kconfig"
2656 source "drivers/cpuidle/Kconfig"
2658 source "drivers/idle/Kconfig"
2662 menu "Bus options (PCI etc.)"
2665 prompt "PCI access mode"
2666 depends on X86_32 && PCI
2669 On PCI systems, the BIOS can be used to detect the PCI devices and
2670 determine their configuration. However, some old PCI motherboards
2671 have BIOS bugs and may crash if this is done. Also, some embedded
2672 PCI-based systems don't have any BIOS at all. Linux can also try to
2673 detect the PCI hardware directly without using the BIOS.
2675 With this option, you can specify how Linux should detect the
2676 PCI devices. If you choose "BIOS", the BIOS will be used,
2677 if you choose "Direct", the BIOS won't be used, and if you
2678 choose "MMConfig", then PCI Express MMCONFIG will be used.
2679 If you choose "Any", the kernel will try MMCONFIG, then the
2680 direct access method and falls back to the BIOS if that doesn't
2681 work. If unsure, go with the default, which is "Any".
2686 config PCI_GOMMCONFIG
2703 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2705 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2708 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2711 bool "Support mmconfig PCI config space access" if X86_64
2713 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2714 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2718 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2722 depends on PCI && XEN
2724 config MMCONF_FAM10H
2726 depends on X86_64 && PCI_MMCONFIG && ACPI
2728 config PCI_CNB20LE_QUIRK
2729 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2732 Read the PCI windows out of the CNB20LE host bridge. This allows
2733 PCI hotplug to work on systems with the CNB20LE chipset which do
2736 There's no public spec for this chipset, and this functionality
2737 is known to be incomplete.
2739 You should say N unless you know you need this.
2742 bool "ISA bus support on modern systems" if EXPERT
2744 Expose ISA bus device drivers and options available for selection and
2745 configuration. Enable this option if your target machine has an ISA
2746 bus. ISA is an older system, displaced by PCI and newer bus
2747 architectures -- if your target machine is modern, it probably does
2748 not have an ISA bus.
2752 # x86_64 have no ISA slots, but can have ISA-style DMA.
2754 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2757 Enables ISA-style DMA support for devices requiring such controllers.
2765 Find out whether you have ISA slots on your motherboard. ISA is the
2766 name of a bus system, i.e. the way the CPU talks to the other stuff
2767 inside your box. Other bus systems are PCI, EISA, MicroChannel
2768 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2769 newer boards don't support it. If you have ISA, say Y, otherwise N.
2772 tristate "NatSemi SCx200 support"
2774 This provides basic support for National Semiconductor's
2775 (now AMD's) Geode processors. The driver probes for the
2776 PCI-IDs of several on-chip devices, so its a good dependency
2777 for other scx200_* drivers.
2779 If compiled as a module, the driver is named scx200.
2781 config SCx200HR_TIMER
2782 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2786 This driver provides a clocksource built upon the on-chip
2787 27MHz high-resolution timer. Its also a workaround for
2788 NSC Geode SC-1100's buggy TSC, which loses time when the
2789 processor goes idle (as is done by the scheduler). The
2790 other workaround is idle=poll boot option.
2793 bool "One Laptop Per Child support"
2801 Add support for detecting the unique features of the OLPC
2805 bool "OLPC XO-1 Power Management"
2806 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2808 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2811 bool "OLPC XO-1 Real Time Clock"
2812 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2814 Add support for the XO-1 real time clock, which can be used as a
2815 programmable wakeup source.
2818 bool "OLPC XO-1 SCI extras"
2819 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2823 Add support for SCI-based features of the OLPC XO-1 laptop:
2824 - EC-driven system wakeups
2828 - AC adapter status updates
2829 - Battery status updates
2831 config OLPC_XO15_SCI
2832 bool "OLPC XO-1.5 SCI extras"
2833 depends on OLPC && ACPI
2836 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2837 - EC-driven system wakeups
2838 - AC adapter status updates
2839 - Battery status updates
2842 bool "PCEngines ALIX System Support (LED setup)"
2845 This option enables system support for the PCEngines ALIX.
2846 At present this just sets up LEDs for GPIO control on
2847 ALIX2/3/6 boards. However, other system specific setup should
2850 Note: You must still enable the drivers for GPIO and LED support
2851 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2853 Note: You have to set alix.force=1 for boards with Award BIOS.
2856 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2859 This option enables system support for the Soekris Engineering net5501.
2862 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2866 This option enables system support for the Traverse Technologies GEOS.
2869 bool "Technologic Systems TS-5500 platform support"
2871 select CHECK_SIGNATURE
2875 This option enables system support for the Technologic Systems TS-5500.
2881 depends on CPU_SUP_AMD && PCI
2885 menu "Binary Emulations"
2887 config IA32_EMULATION
2888 bool "IA32 Emulation"
2890 select ARCH_WANT_OLD_COMPAT_IPC
2892 select COMPAT_OLD_SIGACTION
2894 Include code to run legacy 32-bit programs under a
2895 64-bit kernel. You should likely turn this on, unless you're
2896 100% sure that you don't have any 32-bit programs left.
2899 bool "x32 ABI for 64-bit mode"
2901 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2902 # compressed debug sections to x86_x32 properly:
2903 # https://github.com/ClangBuiltLinux/linux/issues/514
2904 # https://github.com/ClangBuiltLinux/linux/issues/1141
2905 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2907 Include code to run binaries for the x32 native 32-bit ABI
2908 for 64-bit processors. An x32 process gets access to the
2909 full 64-bit register file and wide data path while leaving
2910 pointers at 32 bits for smaller memory footprint.
2914 depends on IA32_EMULATION || X86_32
2916 select OLD_SIGSUSPEND3
2920 depends on IA32_EMULATION || X86_X32_ABI
2922 config COMPAT_FOR_U64_ALIGNMENT
2928 config HAVE_ATOMIC_IOMAP
2932 source "arch/x86/kvm/Kconfig"
2934 source "arch/x86/Kconfig.assembler"