1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
71 select ARCH_HAS_CACHE_LINE_SIZE
72 select ARCH_HAS_CURRENT_STACK_POINTER
73 select ARCH_HAS_DEBUG_VIRTUAL
74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
75 select ARCH_HAS_DEVMEM_IS_ALLOWED
76 select ARCH_HAS_EARLY_DEBUG if KGDB
77 select ARCH_HAS_ELF_RANDOMIZE
78 select ARCH_HAS_FAST_MULTIPLIER
79 select ARCH_HAS_FORTIFY_SOURCE
80 select ARCH_HAS_GCOV_PROFILE_ALL
81 select ARCH_HAS_KCOV if X86_64
82 select ARCH_HAS_MEM_ENCRYPT
83 select ARCH_HAS_MEMBARRIER_SYNC_CORE
84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85 select ARCH_HAS_PMEM_API if X86_64
86 select ARCH_HAS_PTE_DEVMAP if X86_64
87 select ARCH_HAS_PTE_SPECIAL
88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
89 select ARCH_HAS_COPY_MC if X86_64
90 select ARCH_HAS_SET_MEMORY
91 select ARCH_HAS_SET_DIRECT_MAP
92 select ARCH_HAS_STRICT_KERNEL_RWX
93 select ARCH_HAS_STRICT_MODULE_RWX
94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95 select ARCH_HAS_SYSCALL_WRAPPER
96 select ARCH_HAS_UBSAN_SANITIZE_ALL
97 select ARCH_HAS_VM_GET_PAGE_PROT
98 select ARCH_HAS_DEBUG_WX
99 select ARCH_HAS_ZONE_DMA_SET if EXPERT
100 select ARCH_HAVE_NMI_SAFE_CMPXCHG
101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
102 select ARCH_MIGHT_HAVE_PC_PARPORT
103 select ARCH_MIGHT_HAVE_PC_SERIO
104 select ARCH_STACKWALK
105 select ARCH_SUPPORTS_ACPI
106 select ARCH_SUPPORTS_ATOMIC_RMW
107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
111 select ARCH_SUPPORTS_LTO_CLANG
112 select ARCH_SUPPORTS_LTO_CLANG_THIN
113 select ARCH_USE_BUILTIN_BSWAP
114 select ARCH_USE_MEMTEST
115 select ARCH_USE_QUEUED_RWLOCKS
116 select ARCH_USE_QUEUED_SPINLOCKS
117 select ARCH_USE_SYM_ANNOTATIONS
118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
121 select ARCH_WANTS_NO_INSTR
122 select ARCH_WANT_GENERAL_HUGETLB
123 select ARCH_WANT_HUGE_PMD_SHARE
124 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
125 select ARCH_WANT_LD_ORPHAN_WARN
126 select ARCH_WANTS_THP_SWAP if X86_64
127 select ARCH_HAS_PARANOID_L1D_FLUSH
128 select BUILDTIME_TABLE_SORT
130 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
131 select CLOCKSOURCE_WATCHDOG
132 select DCACHE_WORD_ACCESS
133 select DYNAMIC_SIGFRAME
134 select EDAC_ATOMIC_SCRUB
136 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
137 select GENERIC_CLOCKEVENTS_MIN_ADJUST
138 select GENERIC_CMOS_UPDATE
139 select GENERIC_CPU_AUTOPROBE
140 select GENERIC_CPU_VULNERABILITIES
141 select GENERIC_EARLY_IOREMAP
144 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
145 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
146 select GENERIC_IRQ_MIGRATION if SMP
147 select GENERIC_IRQ_PROBE
148 select GENERIC_IRQ_RESERVATION_MODE
149 select GENERIC_IRQ_SHOW
150 select GENERIC_PENDING_IRQ if SMP
151 select GENERIC_PTDUMP
152 select GENERIC_SMP_IDLE_THREAD
153 select GENERIC_TIME_VSYSCALL
154 select GENERIC_GETTIMEOFDAY
155 select GENERIC_VDSO_TIME_NS
156 select GUP_GET_PTE_LOW_HIGH if X86_PAE
157 select HARDIRQS_SW_RESEND
158 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
159 select HAVE_ACPI_APEI if ACPI
160 select HAVE_ACPI_APEI_NMI if ACPI
161 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
162 select HAVE_ARCH_AUDITSYSCALL
163 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
164 select HAVE_ARCH_HUGE_VMALLOC if X86_64
165 select HAVE_ARCH_JUMP_LABEL
166 select HAVE_ARCH_JUMP_LABEL_RELATIVE
167 select HAVE_ARCH_KASAN if X86_64
168 select HAVE_ARCH_KASAN_VMALLOC if X86_64
169 select HAVE_ARCH_KFENCE
170 select HAVE_ARCH_KGDB
171 select HAVE_ARCH_MMAP_RND_BITS if MMU
172 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
173 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
174 select HAVE_ARCH_PREL32_RELOCATIONS
175 select HAVE_ARCH_SECCOMP_FILTER
176 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
177 select HAVE_ARCH_STACKLEAK
178 select HAVE_ARCH_TRACEHOOK
179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
181 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
182 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
183 select HAVE_ARCH_VMAP_STACK if X86_64
184 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
185 select HAVE_ARCH_WITHIN_STACK_FRAMES
186 select HAVE_ASM_MODVERSIONS
187 select HAVE_CMPXCHG_DOUBLE
188 select HAVE_CMPXCHG_LOCAL
189 select HAVE_CONTEXT_TRACKING if X86_64
190 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
191 select HAVE_C_RECORDMCOUNT
192 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
193 select HAVE_BUILDTIME_MCOUNT_SORT
194 select HAVE_DEBUG_KMEMLEAK
195 select HAVE_DMA_CONTIGUOUS
196 select HAVE_DYNAMIC_FTRACE
197 select HAVE_DYNAMIC_FTRACE_WITH_REGS
198 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
199 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
200 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
201 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
203 select HAVE_EFFICIENT_UNALIGNED_ACCESS
205 select HAVE_EXIT_THREAD
207 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
208 select HAVE_FTRACE_MCOUNT_RECORD
209 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
210 select HAVE_FUNCTION_TRACER
211 select HAVE_GCC_PLUGINS
212 select HAVE_HW_BREAKPOINT
213 select HAVE_IOREMAP_PROT
214 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
215 select HAVE_IRQ_TIME_ACCOUNTING
216 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
217 select HAVE_KERNEL_BZIP2
218 select HAVE_KERNEL_GZIP
219 select HAVE_KERNEL_LZ4
220 select HAVE_KERNEL_LZMA
221 select HAVE_KERNEL_LZO
222 select HAVE_KERNEL_XZ
223 select HAVE_KERNEL_ZSTD
225 select HAVE_KPROBES_ON_FTRACE
226 select HAVE_FUNCTION_ERROR_INJECTION
227 select HAVE_KRETPROBES
230 select HAVE_LIVEPATCH if X86_64
231 select HAVE_MIXED_BREAKPOINTS_REGS
232 select HAVE_MOD_ARCH_SPECIFIC
235 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
237 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
238 select HAVE_OBJTOOL if X86_64
239 select HAVE_OPTPROBES
240 select HAVE_PCSPKR_PLATFORM
241 select HAVE_PERF_EVENTS
242 select HAVE_PERF_EVENTS_NMI
243 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
245 select HAVE_PERF_REGS
246 select HAVE_PERF_USER_STACK_DUMP
247 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
248 select MMU_GATHER_MERGE_VMAS
249 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
250 select HAVE_REGS_AND_STACK_ACCESS_API
251 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
252 select HAVE_FUNCTION_ARG_ACCESS_API
253 select HAVE_SETUP_PER_CPU_AREA
254 select HAVE_SOFTIRQ_ON_OWN_STACK
255 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
256 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
257 select HAVE_STATIC_CALL
258 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
259 select HAVE_PREEMPT_DYNAMIC_CALL
261 select HAVE_SYSCALL_TRACEPOINTS
262 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
263 select HAVE_UNSTABLE_SCHED_CLOCK
264 select HAVE_USER_RETURN_NOTIFIER
265 select HAVE_GENERIC_VDSO
266 select HOTPLUG_SMT if SMP
267 select IRQ_FORCED_THREADING
268 select NEED_PER_CPU_EMBED_FIRST_CHUNK
269 select NEED_PER_CPU_PAGE_FIRST_CHUNK
270 select NEED_SG_DMA_LENGTH
271 select PCI_DOMAINS if PCI
272 select PCI_LOCKLESS_CONFIG if PCI
275 select RTC_MC146818_LIB
278 select SYSCTL_EXCEPTION_TRACE
279 select THREAD_INFO_IN_TASK
280 select TRACE_IRQFLAGS_SUPPORT
281 select USER_STACKTRACE_SUPPORT
283 select HAVE_ARCH_KCSAN if X86_64
284 select X86_FEATURE_NAMES if PROC_FS
285 select PROC_PID_ARCH_STATUS if PROC_FS
286 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
287 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
289 config INSTRUCTION_DECODER
291 depends on KPROBES || PERF_EVENTS || UPROBES
295 default "elf32-i386" if X86_32
296 default "elf64-x86-64" if X86_64
298 config LOCKDEP_SUPPORT
301 config STACKTRACE_SUPPORT
307 config ARCH_MMAP_RND_BITS_MIN
311 config ARCH_MMAP_RND_BITS_MAX
315 config ARCH_MMAP_RND_COMPAT_BITS_MIN
318 config ARCH_MMAP_RND_COMPAT_BITS_MAX
324 config GENERIC_ISA_DMA
326 depends on ISA_DMA_API
331 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
333 config GENERIC_BUG_RELATIVE_POINTERS
336 config ARCH_MAY_HAVE_PC_FDC
338 depends on ISA_DMA_API
340 config GENERIC_CALIBRATE_DELAY
343 config ARCH_HAS_CPU_RELAX
346 config ARCH_HIBERNATION_POSSIBLE
351 default 1024 if X86_64
354 config ARCH_SUSPEND_POSSIBLE
360 config KASAN_SHADOW_OFFSET
363 default 0xdffffc0000000000
365 config HAVE_INTEL_TXT
367 depends on INTEL_IOMMU && ACPI
371 depends on X86_32 && SMP
375 depends on X86_64 && SMP
377 config ARCH_SUPPORTS_UPROBES
380 config FIX_EARLYCON_MEM
383 config DYNAMIC_PHYSICAL_MASK
386 config PGTABLE_LEVELS
388 default 5 if X86_5LEVEL
393 config CC_HAS_SANE_STACKPROTECTOR
395 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
396 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
398 We have to make sure stack protector is unconditionally disabled if
399 the compiler produces broken code or if it does not let us control
400 the segment on 32-bit kernels.
402 menu "Processor type and features"
405 bool "Symmetric multi-processing support"
407 This enables support for systems with more than one CPU. If you have
408 a system with only one CPU, say N. If you have a system with more
411 If you say N here, the kernel will run on uni- and multiprocessor
412 machines, but will use only one CPU of a multiprocessor machine. If
413 you say Y here, the kernel will run on many, but not all,
414 uniprocessor machines. On a uniprocessor machine, the kernel
415 will run faster if you say N here.
417 Note that if you say Y here and choose architecture "586" or
418 "Pentium" under "Processor family", the kernel will not work on 486
419 architectures. Similarly, multiprocessor kernels for the "PPro"
420 architecture may not work on all Pentium based boards.
422 People using multiprocessor machines who say Y here should also say
423 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
424 Management" code will be disabled if you say Y here.
426 See also <file:Documentation/x86/i386/IO-APIC.rst>,
427 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
428 <http://www.tldp.org/docs.html#howto>.
430 If you don't know what to do here, say N.
432 config X86_FEATURE_NAMES
433 bool "Processor feature human-readable names" if EMBEDDED
436 This option compiles in a table of x86 feature bits and corresponding
437 names. This is required to support /proc/cpuinfo and a few kernel
438 messages. You can disable this to save space, at the expense of
439 making those few kernel messages show numeric feature bits instead.
444 bool "Support x2apic"
445 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
447 This enables x2apic support on CPUs that have this feature.
449 This allows 32-bit apic IDs (so it can support very large systems),
450 and accesses the local apic via MSRs not via mmio.
452 If you don't know what to do here, say N.
455 bool "Enable MPS table" if ACPI
457 depends on X86_LOCAL_APIC
459 For old smp systems that do not have proper acpi support. Newer systems
460 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
464 depends on X86_GOLDFISH
466 config X86_CPU_RESCTRL
467 bool "x86 CPU resource control support"
468 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
470 select PROC_CPU_RESCTRL if PROC_FS
472 Enable x86 CPU resource control support.
474 Provide support for the allocation and monitoring of system resources
477 Intel calls this Intel Resource Director Technology
478 (Intel(R) RDT). More information about RDT can be found in the
479 Intel x86 Architecture Software Developer Manual.
481 AMD calls this AMD Platform Quality of Service (AMD QoS).
482 More information about AMD QoS can be found in the AMD64 Technology
483 Platform Quality of Service Extensions manual.
489 bool "Support for big SMP systems with more than 8 CPUs"
492 This option is needed for the systems that have more than 8 CPUs.
494 config X86_EXTENDED_PLATFORM
495 bool "Support for extended (non-PC) x86 platforms"
498 If you disable this option then the kernel will only support
499 standard PC platforms. (which covers the vast majority of
502 If you enable this option then you'll be able to select support
503 for the following (non-PC) 32 bit x86 platforms:
504 Goldfish (Android emulator)
507 SGI 320/540 (Visual Workstation)
508 STA2X11-based (e.g. Northville)
509 Moorestown MID devices
511 If you have one of these systems, or if you want to build a
512 generic distribution kernel, say Y here - otherwise say N.
516 config X86_EXTENDED_PLATFORM
517 bool "Support for extended (non-PC) x86 platforms"
520 If you disable this option then the kernel will only support
521 standard PC platforms. (which covers the vast majority of
524 If you enable this option then you'll be able to select support
525 for the following (non-PC) 64 bit x86 platforms:
530 If you have one of these systems, or if you want to build a
531 generic distribution kernel, say Y here - otherwise say N.
533 # This is an alphabetically sorted list of 64 bit extended platforms
534 # Please maintain the alphabetic order if and when there are additions
536 bool "Numascale NumaChip"
538 depends on X86_EXTENDED_PLATFORM
541 depends on X86_X2APIC
542 depends on PCI_MMCONFIG
544 Adds support for Numascale NumaChip large-SMP systems. Needed to
545 enable more than ~168 cores.
546 If you don't have one of these, you should say N here.
550 select HYPERVISOR_GUEST
552 depends on X86_64 && PCI
553 depends on X86_EXTENDED_PLATFORM
556 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
557 supposed to run on these EM64T-based machines. Only choose this option
558 if you have one of these machines.
561 bool "SGI Ultraviolet"
563 depends on X86_EXTENDED_PLATFORM
566 depends on KEXEC_CORE
567 depends on X86_X2APIC
570 This option is needed in order to support SGI Ultraviolet systems.
571 If you don't have one of these, you should say N here.
573 # Following is an alphabetically sorted list of 32 bit extended platforms
574 # Please maintain the alphabetic order if and when there are additions
577 bool "Goldfish (Virtual Platform)"
578 depends on X86_EXTENDED_PLATFORM
580 Enable support for the Goldfish virtual platform used primarily
581 for Android development. Unless you are building for the Android
582 Goldfish emulator say N here.
585 bool "CE4100 TV platform"
587 depends on PCI_GODIRECT
588 depends on X86_IO_APIC
590 depends on X86_EXTENDED_PLATFORM
591 select X86_REBOOTFIXUPS
593 select OF_EARLY_FLATTREE
595 Select for the Intel CE media processor (CE4100) SOC.
596 This option compiles in support for the CE4100 SOC for settop
597 boxes and media devices.
600 bool "Intel MID platform support"
601 depends on X86_EXTENDED_PLATFORM
602 depends on X86_PLATFORM_DEVICES
604 depends on X86_64 || (PCI_GOANY && X86_32)
605 depends on X86_IO_APIC
610 Select to build a kernel capable of supporting Intel MID (Mobile
611 Internet Device) platform systems which do not have the PCI legacy
612 interfaces. If you are building for a PC class system say N here.
614 Intel MID platforms are based on an Intel processor and chipset which
615 consume less power than most of the x86 derivatives.
617 config X86_INTEL_QUARK
618 bool "Intel Quark platform support"
620 depends on X86_EXTENDED_PLATFORM
621 depends on X86_PLATFORM_DEVICES
625 depends on X86_IO_APIC
630 Select to include support for Quark X1000 SoC.
631 Say Y here if you have a Quark based system such as the Arduino
632 compatible Intel Galileo.
634 config X86_INTEL_LPSS
635 bool "Intel Low Power Subsystem Support"
636 depends on X86 && ACPI && PCI
641 Select to build support for Intel Low Power Subsystem such as
642 found on Intel Lynxpoint PCH. Selecting this option enables
643 things like clock tree (common clock framework) and pincontrol
644 which are needed by the LPSS peripheral drivers.
646 config X86_AMD_PLATFORM_DEVICE
647 bool "AMD ACPI2Platform devices support"
652 Select to interpret AMD specific ACPI device to platform device
653 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
654 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
655 implemented under PINCTRL subsystem.
658 tristate "Intel SoC IOSF Sideband support for SoC platforms"
661 This option enables sideband register access support for Intel SoC
662 platforms. On these platforms the IOSF sideband is used in lieu of
663 MSR's for some register accesses, mostly but not limited to thermal
664 and power. Drivers may query the availability of this device to
665 determine if they need the sideband in order to work on these
666 platforms. The sideband is available on the following SoC products.
667 This list is not meant to be exclusive.
672 You should say Y if you are running a kernel on one of these SoC's.
674 config IOSF_MBI_DEBUG
675 bool "Enable IOSF sideband access through debugfs"
676 depends on IOSF_MBI && DEBUG_FS
678 Select this option to expose the IOSF sideband access registers (MCR,
679 MDR, MCRX) through debugfs to write and read register information from
680 different units on the SoC. This is most useful for obtaining device
681 state information for debug and analysis. As this is a general access
682 mechanism, users of this option would have specific knowledge of the
683 device they want to access.
685 If you don't require the option or are in doubt, say N.
688 bool "RDC R-321x SoC"
690 depends on X86_EXTENDED_PLATFORM
692 select X86_REBOOTFIXUPS
694 This option is needed for RDC R-321x system-on-chip, also known
696 If you don't have one of these chips, you should say N here.
698 config X86_32_NON_STANDARD
699 bool "Support non-standard 32-bit SMP architectures"
700 depends on X86_32 && SMP
701 depends on X86_EXTENDED_PLATFORM
703 This option compiles in the bigsmp and STA2X11 default
704 subarchitectures. It is intended for a generic binary
705 kernel. If you select them all, kernel will probe it one by
706 one and will fallback to default.
708 # Alphabetically sorted list of Non standard 32 bit platforms
710 config X86_SUPPORTS_MEMORY_FAILURE
712 # MCE code calls memory_failure():
714 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
715 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
716 depends on X86_64 || !SPARSEMEM
717 select ARCH_SUPPORTS_MEMORY_FAILURE
720 bool "STA2X11 Companion Chip Support"
721 depends on X86_32_NON_STANDARD && PCI
726 This adds support for boards based on the STA2X11 IO-Hub,
727 a.k.a. "ConneXt". The chip is used in place of the standard
728 PC chipset, so all "standard" peripherals are missing. If this
729 option is selected the kernel will still be able to boot on
730 standard PC machines.
733 tristate "Eurobraille/Iris poweroff module"
736 The Iris machines from EuroBraille do not have APM or ACPI support
737 to shut themselves down properly. A special I/O sequence is
738 needed to do so, which is what this module does at
741 This is only for Iris machines from EuroBraille.
745 config SCHED_OMIT_FRAME_POINTER
747 prompt "Single-depth WCHAN output"
750 Calculate simpler /proc/<PID>/wchan values. If this option
751 is disabled then wchan values will recurse back to the
752 caller function. This provides more accurate wchan values,
753 at the expense of slightly more scheduling overhead.
755 If in doubt, say "Y".
757 menuconfig HYPERVISOR_GUEST
758 bool "Linux guest support"
760 Say Y here to enable options for running Linux under various hyper-
761 visors. This option enables basic hypervisor detection and platform
764 If you say N, all options in this submenu will be skipped and
765 disabled, and Linux guest support won't be built in.
770 bool "Enable paravirtualization code"
771 depends on HAVE_STATIC_CALL
773 This changes the kernel so it can modify itself when it is run
774 under a hypervisor, potentially improving performance significantly
775 over full virtualization. However, when run without a hypervisor
776 the kernel is theoretically slower and slightly larger.
781 config PARAVIRT_DEBUG
782 bool "paravirt-ops debugging"
783 depends on PARAVIRT && DEBUG_KERNEL
785 Enable to debug paravirt_ops internals. Specifically, BUG if
786 a paravirt_op is missing when it is called.
788 config PARAVIRT_SPINLOCKS
789 bool "Paravirtualization layer for spinlocks"
790 depends on PARAVIRT && SMP
792 Paravirtualized spinlocks allow a pvops backend to replace the
793 spinlock implementation with something virtualization-friendly
794 (for example, block the virtual CPU rather than spinning).
796 It has a minimal impact on native kernels and gives a nice performance
797 benefit on paravirtualized KVM / Xen kernels.
799 If you are unsure how to answer this question, answer Y.
801 config X86_HV_CALLBACK_VECTOR
804 source "arch/x86/xen/Kconfig"
807 bool "KVM Guest support (including kvmclock)"
809 select PARAVIRT_CLOCK
810 select ARCH_CPUIDLE_HALTPOLL
811 select X86_HV_CALLBACK_VECTOR
814 This option enables various optimizations for running under the KVM
815 hypervisor. It includes a paravirtualized clock, so that instead
816 of relying on a PIT (or probably other) emulation by the
817 underlying device model, the host provides the guest with
818 timing infrastructure such as time of day, and system time
820 config ARCH_CPUIDLE_HALTPOLL
822 prompt "Disable host haltpoll when loading haltpoll driver"
824 If virtualized under KVM, disable host haltpoll.
827 bool "Support for running PVH guests"
829 This option enables the PVH entry point for guest virtual machines
830 as specified in the x86/HVM direct boot ABI.
832 config PARAVIRT_TIME_ACCOUNTING
833 bool "Paravirtual steal time accounting"
836 Select this option to enable fine granularity task steal time
837 accounting. Time spent executing other tasks in parallel with
838 the current vCPU is discounted from the vCPU power. To account for
839 that, there can be a small performance impact.
841 If in doubt, say N here.
843 config PARAVIRT_CLOCK
846 config JAILHOUSE_GUEST
847 bool "Jailhouse non-root cell support"
848 depends on X86_64 && PCI
851 This option allows to run Linux as guest in a Jailhouse non-root
852 cell. You can leave this option disabled if you only want to start
853 Jailhouse and run Linux afterwards in the root cell.
856 bool "ACRN Guest support"
858 select X86_HV_CALLBACK_VECTOR
860 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
861 a flexible, lightweight reference open-source hypervisor, built with
862 real-time and safety-criticality in mind. It is built for embedded
863 IOT with small footprint and real-time features. More details can be
864 found in https://projectacrn.org/.
866 config INTEL_TDX_GUEST
867 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
868 depends on X86_64 && CPU_SUP_INTEL
869 depends on X86_X2APIC
870 select ARCH_HAS_CC_PLATFORM
871 select X86_MEM_ENCRYPT
874 Support running as a guest under Intel TDX. Without this support,
875 the guest kernel can not boot or run under TDX.
876 TDX includes memory encryption and integrity capabilities
877 which protect the confidentiality and integrity of guest
878 memory contents and CPU state. TDX guests are protected from
879 some attacks from the VMM.
881 endif # HYPERVISOR_GUEST
883 source "arch/x86/Kconfig.cpu"
887 prompt "HPET Timer Support" if X86_32
889 Use the IA-PC HPET (High Precision Event Timer) to manage
890 time in preference to the PIT and RTC, if a HPET is
892 HPET is the next generation timer replacing legacy 8254s.
893 The HPET provides a stable time base on SMP
894 systems, unlike the TSC, but it is more expensive to access,
895 as it is off-chip. The interface used is documented
896 in the HPET spec, revision 1.
898 You can safely choose Y here. However, HPET will only be
899 activated if the platform and the BIOS support this feature.
900 Otherwise the 8254 will be used for timing services.
902 Choose N to continue using the legacy 8254 timer.
904 config HPET_EMULATE_RTC
906 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
908 # Mark as expert because too many people got it wrong.
909 # The code disables itself when not needed.
912 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
913 bool "Enable DMI scanning" if EXPERT
915 Enabled scanning of DMI to identify machine quirks. Say Y
916 here unless you have verified that your setup is not
917 affected by entries in the DMI blacklist. Required by PNP
921 bool "Old AMD GART IOMMU support"
925 depends on X86_64 && PCI && AMD_NB
927 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
928 GART based hardware IOMMUs.
930 The GART supports full DMA access for devices with 32-bit access
931 limitations, on systems with more than 3 GB. This is usually needed
932 for USB, sound, many IDE/SATA chipsets and some other devices.
934 Newer systems typically have a modern AMD IOMMU, supported via
935 the CONFIG_AMD_IOMMU=y config option.
937 In normal configurations this driver is only active when needed:
938 there's more than 3 GB of memory and the system contains a
939 32-bit limited device.
943 config BOOT_VESA_SUPPORT
946 If true, at least one selected framebuffer driver can take advantage
947 of VESA video modes set at an early boot stage via the vga= parameter.
950 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
951 depends on X86_64 && SMP && DEBUG_KERNEL
952 select CPUMASK_OFFSTACK
954 Enable maximum number of CPUS and NUMA Nodes for this architecture.
958 # The maximum number of CPUs supported:
960 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
961 # and which can be configured interactively in the
962 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
964 # The ranges are different on 32-bit and 64-bit kernels, depending on
965 # hardware capabilities and scalability features of the kernel.
967 # ( If MAXSMP is enabled we just use the highest possible value and disable
968 # interactive configuration. )
971 config NR_CPUS_RANGE_BEGIN
973 default NR_CPUS_RANGE_END if MAXSMP
977 config NR_CPUS_RANGE_END
980 default 64 if SMP && X86_BIGSMP
981 default 8 if SMP && !X86_BIGSMP
984 config NR_CPUS_RANGE_END
987 default 8192 if SMP && CPUMASK_OFFSTACK
988 default 512 if SMP && !CPUMASK_OFFSTACK
991 config NR_CPUS_DEFAULT
994 default 32 if X86_BIGSMP
998 config NR_CPUS_DEFAULT
1001 default 8192 if MAXSMP
1006 int "Maximum number of CPUs" if SMP && !MAXSMP
1007 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1008 default NR_CPUS_DEFAULT
1010 This allows you to specify the maximum number of CPUs which this
1011 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1012 supported value is 8192, otherwise the maximum value is 512. The
1013 minimum value which makes sense is 2.
1015 This is purely to save memory: each supported CPU adds about 8KB
1016 to the kernel image.
1018 config SCHED_CLUSTER
1019 bool "Cluster scheduler support"
1023 Cluster scheduler support improves the CPU scheduler's decision
1024 making when dealing with machines that have clusters of CPUs.
1025 Cluster usually means a couple of CPUs which are placed closely
1026 by sharing mid-level caches, last-level cache tags or internal
1034 prompt "Multi-core scheduler support"
1037 Multi-core scheduler support improves the CPU scheduler's decision
1038 making when dealing with multi-core CPU chips at a cost of slightly
1039 increased overhead in some places. If unsure say N here.
1041 config SCHED_MC_PRIO
1042 bool "CPU core priorities scheduler support"
1043 depends on SCHED_MC && CPU_SUP_INTEL
1044 select X86_INTEL_PSTATE
1048 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1049 core ordering determined at manufacturing time, which allows
1050 certain cores to reach higher turbo frequencies (when running
1051 single threaded workloads) than others.
1053 Enabling this kernel feature teaches the scheduler about
1054 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1055 scheduler's CPU selection logic accordingly, so that higher
1056 overall system performance can be achieved.
1058 This feature will have no effect on CPUs without this feature.
1060 If unsure say Y here.
1064 depends on !SMP && X86_LOCAL_APIC
1067 bool "Local APIC support on uniprocessors" if !PCI_MSI
1069 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1071 A local APIC (Advanced Programmable Interrupt Controller) is an
1072 integrated interrupt controller in the CPU. If you have a single-CPU
1073 system which has a processor with a local APIC, you can say Y here to
1074 enable and use it. If you say Y here even though your machine doesn't
1075 have a local APIC, then the kernel will still run with no slowdown at
1076 all. The local APIC supports CPU-generated self-interrupts (timer,
1077 performance counters), and the NMI watchdog which detects hard
1080 config X86_UP_IOAPIC
1081 bool "IO-APIC support on uniprocessors"
1082 depends on X86_UP_APIC
1084 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1085 SMP-capable replacement for PC-style interrupt controllers. Most
1086 SMP systems and many recent uniprocessor systems have one.
1088 If you have a single-CPU system with an IO-APIC, you can say Y here
1089 to use it. If you say Y here even though your machine doesn't have
1090 an IO-APIC, then the kernel will still run with no slowdown at all.
1092 config X86_LOCAL_APIC
1094 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1095 select IRQ_DOMAIN_HIERARCHY
1096 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1100 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1102 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1103 bool "Reroute for broken boot IRQs"
1104 depends on X86_IO_APIC
1106 This option enables a workaround that fixes a source of
1107 spurious interrupts. This is recommended when threaded
1108 interrupt handling is used on systems where the generation of
1109 superfluous "boot interrupts" cannot be disabled.
1111 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1112 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1113 kernel does during interrupt handling). On chipsets where this
1114 boot IRQ generation cannot be disabled, this workaround keeps
1115 the original IRQ line masked so that only the equivalent "boot
1116 IRQ" is delivered to the CPUs. The workaround also tells the
1117 kernel to set up the IRQ handler on the boot IRQ line. In this
1118 way only one interrupt is delivered to the kernel. Otherwise
1119 the spurious second interrupt may cause the kernel to bring
1120 down (vital) interrupt lines.
1122 Only affects "broken" chipsets. Interrupt sharing may be
1123 increased on these systems.
1126 bool "Machine Check / overheating reporting"
1127 select GENERIC_ALLOCATOR
1130 Machine Check support allows the processor to notify the
1131 kernel if it detects a problem (e.g. overheating, data corruption).
1132 The action the kernel takes depends on the severity of the problem,
1133 ranging from warning messages to halting the machine.
1135 config X86_MCELOG_LEGACY
1136 bool "Support for deprecated /dev/mcelog character device"
1139 Enable support for /dev/mcelog which is needed by the old mcelog
1140 userspace logging daemon. Consider switching to the new generation
1143 config X86_MCE_INTEL
1145 prompt "Intel MCE features"
1146 depends on X86_MCE && X86_LOCAL_APIC
1148 Additional support for intel specific MCE features such as
1149 the thermal monitor.
1153 prompt "AMD MCE features"
1154 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1156 Additional support for AMD specific MCE features such as
1157 the DRAM Error Threshold.
1159 config X86_ANCIENT_MCE
1160 bool "Support for old Pentium 5 / WinChip machine checks"
1161 depends on X86_32 && X86_MCE
1163 Include support for machine check handling on old Pentium 5 or WinChip
1164 systems. These typically need to be enabled explicitly on the command
1167 config X86_MCE_THRESHOLD
1168 depends on X86_MCE_AMD || X86_MCE_INTEL
1171 config X86_MCE_INJECT
1172 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1173 tristate "Machine check injector support"
1175 Provide support for injecting machine checks for testing purposes.
1176 If you don't know what a machine check is and you don't do kernel
1177 QA it is safe to say n.
1179 source "arch/x86/events/Kconfig"
1181 config X86_LEGACY_VM86
1182 bool "Legacy VM86 support"
1185 This option allows user programs to put the CPU into V8086
1186 mode, which is an 80286-era approximation of 16-bit real mode.
1188 Some very old versions of X and/or vbetool require this option
1189 for user mode setting. Similarly, DOSEMU will use it if
1190 available to accelerate real mode DOS programs. However, any
1191 recent version of DOSEMU, X, or vbetool should be fully
1192 functional even without kernel VM86 support, as they will all
1193 fall back to software emulation. Nevertheless, if you are using
1194 a 16-bit DOS program where 16-bit performance matters, vm86
1195 mode might be faster than emulation and you might want to
1198 Note that any app that works on a 64-bit kernel is unlikely to
1199 need this option, as 64-bit kernels don't, and can't, support
1200 V8086 mode. This option is also unrelated to 16-bit protected
1201 mode and is not needed to run most 16-bit programs under Wine.
1203 Enabling this option increases the complexity of the kernel
1204 and slows down exception handling a tiny bit.
1206 If unsure, say N here.
1210 default X86_LEGACY_VM86
1213 bool "Enable support for 16-bit segments" if EXPERT
1215 depends on MODIFY_LDT_SYSCALL
1217 This option is required by programs like Wine to run 16-bit
1218 protected mode legacy code on x86 processors. Disabling
1219 this option saves about 300 bytes on i386, or around 6K text
1220 plus 16K runtime memory on x86-64,
1224 depends on X86_16BIT && X86_32
1228 depends on X86_16BIT && X86_64
1230 config X86_VSYSCALL_EMULATION
1231 bool "Enable vsyscall emulation" if EXPERT
1235 This enables emulation of the legacy vsyscall page. Disabling
1236 it is roughly equivalent to booting with vsyscall=none, except
1237 that it will also disable the helpful warning if a program
1238 tries to use a vsyscall. With this option set to N, offending
1239 programs will just segfault, citing addresses of the form
1242 This option is required by many programs built before 2013, and
1243 care should be used even with newer programs if set to N.
1245 Disabling this option saves about 7K of kernel size and
1246 possibly 4K of additional runtime pagetable memory.
1248 config X86_IOPL_IOPERM
1249 bool "IOPERM and IOPL Emulation"
1252 This enables the ioperm() and iopl() syscalls which are necessary
1253 for legacy applications.
1255 Legacy IOPL support is an overbroad mechanism which allows user
1256 space aside of accessing all 65536 I/O ports also to disable
1257 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1258 capabilities and permission from potentially active security
1261 The emulation restricts the functionality of the syscall to
1262 only allowing the full range I/O port access, but prevents the
1263 ability to disable interrupts from user space which would be
1264 granted if the hardware IOPL mechanism would be used.
1267 tristate "Toshiba Laptop support"
1270 This adds a driver to safely access the System Management Mode of
1271 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1272 not work on models with a Phoenix BIOS. The System Management Mode
1273 is used to set the BIOS and power saving options on Toshiba portables.
1275 For information on utilities to make use of this driver see the
1276 Toshiba Linux utilities web site at:
1277 <http://www.buzzard.org.uk/toshiba/>.
1279 Say Y if you intend to run this kernel on a Toshiba portable.
1282 config X86_REBOOTFIXUPS
1283 bool "Enable X86 board specific fixups for reboot"
1286 This enables chipset and/or board specific fixups to be done
1287 in order to get reboot to work correctly. This is only needed on
1288 some combinations of hardware and BIOS. The symptom, for which
1289 this config is intended, is when reboot ends with a stalled/hung
1292 Currently, the only fixup is for the Geode machines using
1293 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1295 Say Y if you want to enable the fixup. Currently, it's safe to
1296 enable this option even if you don't need it.
1300 bool "CPU microcode loading support"
1302 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1304 If you say Y here, you will be able to update the microcode on
1305 Intel and AMD processors. The Intel support is for the IA32 family,
1306 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1307 AMD support is for families 0x10 and later. You will obviously need
1308 the actual microcode binary data itself which is not shipped with
1311 The preferred method to load microcode from a detached initrd is described
1312 in Documentation/x86/microcode.rst. For that you need to enable
1313 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1314 initrd for microcode blobs.
1316 In addition, you can build the microcode into the kernel. For that you
1317 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1320 config MICROCODE_INTEL
1321 bool "Intel microcode loading support"
1322 depends on CPU_SUP_INTEL && MICROCODE
1325 This options enables microcode patch loading support for Intel
1328 For the current Intel microcode data package go to
1329 <https://downloadcenter.intel.com> and search for
1330 'Linux Processor Microcode Data File'.
1332 config MICROCODE_AMD
1333 bool "AMD microcode loading support"
1334 depends on CPU_SUP_AMD && MICROCODE
1336 If you select this option, microcode patch loading support for AMD
1337 processors will be enabled.
1339 config MICROCODE_LATE_LOADING
1340 bool "Late microcode loading (DANGEROUS)"
1342 depends on MICROCODE
1344 Loading microcode late, when the system is up and executing instructions
1345 is a tricky business and should be avoided if possible. Just the sequence
1346 of synchronizing all cores and SMT threads is one fragile dance which does
1347 not guarantee that cores might not softlock after the loading. Therefore,
1348 use this at your own risk. Late loading taints the kernel too.
1351 tristate "/dev/cpu/*/msr - Model-specific register support"
1353 This device gives privileged processes access to the x86
1354 Model-Specific Registers (MSRs). It is a character device with
1355 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1356 MSR accesses are directed to a specific CPU on multi-processor
1360 tristate "/dev/cpu/*/cpuid - CPU information support"
1362 This device gives processes access to the x86 CPUID instruction to
1363 be executed on a specific processor. It is a character device
1364 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1368 prompt "High Memory Support"
1375 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1376 However, the address space of 32-bit x86 processors is only 4
1377 Gigabytes large. That means that, if you have a large amount of
1378 physical memory, not all of it can be "permanently mapped" by the
1379 kernel. The physical memory that's not permanently mapped is called
1382 If you are compiling a kernel which will never run on a machine with
1383 more than 1 Gigabyte total physical RAM, answer "off" here (default
1384 choice and suitable for most users). This will result in a "3GB/1GB"
1385 split: 3GB are mapped so that each process sees a 3GB virtual memory
1386 space and the remaining part of the 4GB virtual memory space is used
1387 by the kernel to permanently map as much physical memory as
1390 If the machine has between 1 and 4 Gigabytes physical RAM, then
1393 If more than 4 Gigabytes is used then answer "64GB" here. This
1394 selection turns Intel PAE (Physical Address Extension) mode on.
1395 PAE implements 3-level paging on IA32 processors. PAE is fully
1396 supported by Linux, PAE mode is implemented on all recent Intel
1397 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1398 then the kernel will not boot on CPUs that don't support PAE!
1400 The actual amount of total physical memory will either be
1401 auto detected or can be forced by using a kernel command line option
1402 such as "mem=256M". (Try "man bootparam" or see the documentation of
1403 your boot loader (lilo or loadlin) about how to pass options to the
1404 kernel at boot time.)
1406 If unsure, say "off".
1411 Select this if you have a 32-bit processor and between 1 and 4
1412 gigabytes of physical RAM.
1416 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1419 Select this if you have a 32-bit processor and more than 4
1420 gigabytes of physical RAM.
1425 prompt "Memory split" if EXPERT
1429 Select the desired split between kernel and user memory.
1431 If the address range available to the kernel is less than the
1432 physical memory installed, the remaining memory will be available
1433 as "high memory". Accessing high memory is a little more costly
1434 than low memory, as it needs to be mapped into the kernel first.
1435 Note that increasing the kernel address space limits the range
1436 available to user programs, making the address space there
1437 tighter. Selecting anything other than the default 3G/1G split
1438 will also likely make your kernel incompatible with binary-only
1441 If you are not absolutely sure what you are doing, leave this
1445 bool "3G/1G user/kernel split"
1446 config VMSPLIT_3G_OPT
1448 bool "3G/1G user/kernel split (for full 1G low memory)"
1450 bool "2G/2G user/kernel split"
1451 config VMSPLIT_2G_OPT
1453 bool "2G/2G user/kernel split (for full 2G low memory)"
1455 bool "1G/3G user/kernel split"
1460 default 0xB0000000 if VMSPLIT_3G_OPT
1461 default 0x80000000 if VMSPLIT_2G
1462 default 0x78000000 if VMSPLIT_2G_OPT
1463 default 0x40000000 if VMSPLIT_1G
1469 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1472 bool "PAE (Physical Address Extension) Support"
1473 depends on X86_32 && !HIGHMEM4G
1474 select PHYS_ADDR_T_64BIT
1477 PAE is required for NX support, and furthermore enables
1478 larger swapspace support for non-overcommit purposes. It
1479 has the cost of more pagetable lookup overhead, and also
1480 consumes more pagetable space per process.
1483 bool "Enable 5-level page tables support"
1485 select DYNAMIC_MEMORY_LAYOUT
1486 select SPARSEMEM_VMEMMAP
1489 5-level paging enables access to larger address space:
1490 upto 128 PiB of virtual address space and 4 PiB of
1491 physical address space.
1493 It will be supported by future Intel CPUs.
1495 A kernel with the option enabled can be booted on machines that
1496 support 4- or 5-level paging.
1498 See Documentation/x86/x86_64/5level-paging.rst for more
1503 config X86_DIRECT_GBPAGES
1507 Certain kernel features effectively disable kernel
1508 linear 1 GB mappings (even if the CPU otherwise
1509 supports them), so don't confuse the user by printing
1510 that we have them enabled.
1512 config X86_CPA_STATISTICS
1513 bool "Enable statistic for Change Page Attribute"
1516 Expose statistics about the Change Page Attribute mechanism, which
1517 helps to determine the effectiveness of preserving large and huge
1518 page mappings when mapping protections are changed.
1520 config X86_MEM_ENCRYPT
1521 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1522 select DYNAMIC_PHYSICAL_MASK
1525 config AMD_MEM_ENCRYPT
1526 bool "AMD Secure Memory Encryption (SME) support"
1527 depends on X86_64 && CPU_SUP_AMD
1528 select DMA_COHERENT_POOL
1529 select ARCH_USE_MEMREMAP_PROT
1530 select INSTRUCTION_DECODER
1531 select ARCH_HAS_CC_PLATFORM
1532 select X86_MEM_ENCRYPT
1534 Say yes to enable support for the encryption of system memory.
1535 This requires an AMD processor that supports Secure Memory
1538 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1539 bool "Activate AMD Secure Memory Encryption (SME) by default"
1540 depends on AMD_MEM_ENCRYPT
1542 Say yes to have system memory encrypted by default if running on
1543 an AMD processor that supports Secure Memory Encryption (SME).
1545 If set to Y, then the encryption of system memory can be
1546 deactivated with the mem_encrypt=off command line option.
1548 If set to N, then the encryption of system memory can be
1549 activated with the mem_encrypt=on command line option.
1551 # Common NUMA Features
1553 bool "NUMA Memory Allocation and Scheduler Support"
1555 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1556 default y if X86_BIGSMP
1557 select USE_PERCPU_NUMA_NODE_ID
1559 Enable NUMA (Non-Uniform Memory Access) support.
1561 The kernel will try to allocate memory used by a CPU on the
1562 local memory controller of the CPU and add some more
1563 NUMA awareness to the kernel.
1565 For 64-bit this is recommended if the system is Intel Core i7
1566 (or later), AMD Opteron, or EM64T NUMA.
1568 For 32-bit this is only needed if you boot a 32-bit
1569 kernel on a 64-bit NUMA platform.
1571 Otherwise, you should say N.
1575 prompt "Old style AMD Opteron NUMA detection"
1576 depends on X86_64 && NUMA && PCI
1578 Enable AMD NUMA node topology detection. You should say Y here if
1579 you have a multi processor AMD system. This uses an old method to
1580 read the NUMA configuration directly from the builtin Northbridge
1581 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1582 which also takes priority if both are compiled in.
1584 config X86_64_ACPI_NUMA
1586 prompt "ACPI NUMA detection"
1587 depends on X86_64 && NUMA && ACPI && PCI
1590 Enable ACPI SRAT based node topology detection.
1593 bool "NUMA emulation"
1596 Enable NUMA emulation. A flat machine will be split
1597 into virtual nodes when booted with "numa=fake=N", where N is the
1598 number of nodes. This is only useful for debugging.
1601 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1603 default "10" if MAXSMP
1604 default "6" if X86_64
1608 Specify the maximum number of NUMA Nodes available on the target
1609 system. Increases memory reserved to accommodate various tables.
1611 config ARCH_FLATMEM_ENABLE
1613 depends on X86_32 && !NUMA
1615 config ARCH_SPARSEMEM_ENABLE
1617 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1618 select SPARSEMEM_STATIC if X86_32
1619 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1621 config ARCH_SPARSEMEM_DEFAULT
1622 def_bool X86_64 || (NUMA && X86_32)
1624 config ARCH_SELECT_MEMORY_MODEL
1626 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1628 config ARCH_MEMORY_PROBE
1629 bool "Enable sysfs memory/probe interface"
1630 depends on MEMORY_HOTPLUG
1632 This option enables a sysfs memory/probe interface for testing.
1633 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1634 If you are unsure how to answer this question, answer N.
1636 config ARCH_PROC_KCORE_TEXT
1638 depends on X86_64 && PROC_KCORE
1640 config ILLEGAL_POINTER_VALUE
1643 default 0xdead000000000000 if X86_64
1645 config X86_PMEM_LEGACY_DEVICE
1648 config X86_PMEM_LEGACY
1649 tristate "Support non-standard NVDIMMs and ADR protected memory"
1650 depends on PHYS_ADDR_T_64BIT
1652 select X86_PMEM_LEGACY_DEVICE
1653 select NUMA_KEEP_MEMINFO if NUMA
1656 Treat memory marked using the non-standard e820 type of 12 as used
1657 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1658 The kernel will offer these regions to the 'pmem' driver so
1659 they can be used for persistent storage.
1664 bool "Allocate 3rd-level pagetables from highmem"
1667 The VM uses one page table entry for each page of physical memory.
1668 For systems with a lot of RAM, this can be wasteful of precious
1669 low memory. Setting this option will put user-space page table
1670 entries in high memory.
1672 config X86_CHECK_BIOS_CORRUPTION
1673 bool "Check for low memory corruption"
1675 Periodically check for memory corruption in low memory, which
1676 is suspected to be caused by BIOS. Even when enabled in the
1677 configuration, it is disabled at runtime. Enable it by
1678 setting "memory_corruption_check=1" on the kernel command
1679 line. By default it scans the low 64k of memory every 60
1680 seconds; see the memory_corruption_check_size and
1681 memory_corruption_check_period parameters in
1682 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1684 When enabled with the default parameters, this option has
1685 almost no overhead, as it reserves a relatively small amount
1686 of memory and scans it infrequently. It both detects corruption
1687 and prevents it from affecting the running system.
1689 It is, however, intended as a diagnostic tool; if repeatable
1690 BIOS-originated corruption always affects the same memory,
1691 you can use memmap= to prevent the kernel from using that
1694 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1695 bool "Set the default setting of memory_corruption_check"
1696 depends on X86_CHECK_BIOS_CORRUPTION
1699 Set whether the default state of memory_corruption_check is
1702 config MATH_EMULATION
1704 depends on MODIFY_LDT_SYSCALL
1705 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1707 Linux can emulate a math coprocessor (used for floating point
1708 operations) if you don't have one. 486DX and Pentium processors have
1709 a math coprocessor built in, 486SX and 386 do not, unless you added
1710 a 487DX or 387, respectively. (The messages during boot time can
1711 give you some hints here ["man dmesg"].) Everyone needs either a
1712 coprocessor or this emulation.
1714 If you don't have a math coprocessor, you need to say Y here; if you
1715 say Y here even though you have a coprocessor, the coprocessor will
1716 be used nevertheless. (This behavior can be changed with the kernel
1717 command line option "no387", which comes handy if your coprocessor
1718 is broken. Try "man bootparam" or see the documentation of your boot
1719 loader (lilo or loadlin) about how to pass options to the kernel at
1720 boot time.) This means that it is a good idea to say Y here if you
1721 intend to use this kernel on different machines.
1723 More information about the internals of the Linux math coprocessor
1724 emulation can be found in <file:arch/x86/math-emu/README>.
1726 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1727 kernel, it won't hurt.
1731 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1733 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1734 the Memory Type Range Registers (MTRRs) may be used to control
1735 processor access to memory ranges. This is most useful if you have
1736 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1737 allows bus write transfers to be combined into a larger transfer
1738 before bursting over the PCI/AGP bus. This can increase performance
1739 of image write operations 2.5 times or more. Saying Y here creates a
1740 /proc/mtrr file which may be used to manipulate your processor's
1741 MTRRs. Typically the X server should use this.
1743 This code has a reasonably generic interface so that similar
1744 control registers on other processors can be easily supported
1747 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1748 Registers (ARRs) which provide a similar functionality to MTRRs. For
1749 these, the ARRs are used to emulate the MTRRs.
1750 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1751 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1752 write-combining. All of these processors are supported by this code
1753 and it makes sense to say Y here if you have one of them.
1755 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1756 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1757 can lead to all sorts of problems, so it's good to say Y here.
1759 You can safely say Y even if your machine doesn't have MTRRs, you'll
1760 just add about 9 KB to your kernel.
1762 See <file:Documentation/x86/mtrr.rst> for more information.
1764 config MTRR_SANITIZER
1766 prompt "MTRR cleanup support"
1769 Convert MTRR layout from continuous to discrete, so X drivers can
1770 add writeback entries.
1772 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1773 The largest mtrr entry size for a continuous block can be set with
1778 config MTRR_SANITIZER_ENABLE_DEFAULT
1779 int "MTRR cleanup enable value (0-1)"
1782 depends on MTRR_SANITIZER
1784 Enable mtrr cleanup default value
1786 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1787 int "MTRR cleanup spare reg num (0-7)"
1790 depends on MTRR_SANITIZER
1792 mtrr cleanup spare entries default, it can be changed via
1793 mtrr_spare_reg_nr=N on the kernel command line.
1797 prompt "x86 PAT support" if EXPERT
1800 Use PAT attributes to setup page level cache control.
1802 PATs are the modern equivalents of MTRRs and are much more
1803 flexible than MTRRs.
1805 Say N here if you see bootup problems (boot crash, boot hang,
1806 spontaneous reboots) or a non-working video driver.
1810 config ARCH_USES_PG_UNCACHED
1816 prompt "x86 architectural random number generator" if EXPERT
1818 Enable the x86 architectural RDRAND instruction
1819 (Intel Bull Mountain technology) to generate random numbers.
1820 If supported, this is a high bandwidth, cryptographically
1821 secure hardware random number generator.
1825 prompt "User Mode Instruction Prevention" if EXPERT
1827 User Mode Instruction Prevention (UMIP) is a security feature in
1828 some x86 processors. If enabled, a general protection fault is
1829 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1830 executed in user mode. These instructions unnecessarily expose
1831 information about the hardware state.
1833 The vast majority of applications do not use these instructions.
1834 For the very few that do, software emulation is provided in
1835 specific cases in protected and virtual-8086 modes. Emulated
1839 # GCC >= 9 and binutils >= 2.29
1840 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1842 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1843 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1844 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1845 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1848 config X86_KERNEL_IBT
1849 prompt "Indirect Branch Tracking"
1851 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1852 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1853 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1856 Build the kernel with support for Indirect Branch Tracking, a
1857 hardware support course-grain forward-edge Control Flow Integrity
1858 protection. It enforces that all indirect calls must land on
1859 an ENDBR instruction, as such, the compiler will instrument the
1860 code with them to make this happen.
1862 In addition to building the kernel with IBT, seal all functions that
1863 are not indirect call targets, avoiding them ever becoming one.
1865 This requires LTO like objtool runs and will slow down the build. It
1866 does significantly reduce the number of ENDBR instructions in the
1869 config X86_INTEL_MEMORY_PROTECTION_KEYS
1870 prompt "Memory Protection Keys"
1872 # Note: only available in 64-bit mode
1873 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1874 select ARCH_USES_HIGH_VMA_FLAGS
1875 select ARCH_HAS_PKEYS
1877 Memory Protection Keys provides a mechanism for enforcing
1878 page-based protections, but without requiring modification of the
1879 page tables when an application changes protection domains.
1881 For details, see Documentation/core-api/protection-keys.rst
1886 prompt "TSX enable mode"
1887 depends on CPU_SUP_INTEL
1888 default X86_INTEL_TSX_MODE_OFF
1890 Intel's TSX (Transactional Synchronization Extensions) feature
1891 allows to optimize locking protocols through lock elision which
1892 can lead to a noticeable performance boost.
1894 On the other hand it has been shown that TSX can be exploited
1895 to form side channel attacks (e.g. TAA) and chances are there
1896 will be more of those attacks discovered in the future.
1898 Therefore TSX is not enabled by default (aka tsx=off). An admin
1899 might override this decision by tsx=on the command line parameter.
1900 Even with TSX enabled, the kernel will attempt to enable the best
1901 possible TAA mitigation setting depending on the microcode available
1902 for the particular machine.
1904 This option allows to set the default tsx mode between tsx=on, =off
1905 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1908 Say off if not sure, auto if TSX is in use but it should be used on safe
1909 platforms or on if TSX is in use and the security aspect of tsx is not
1912 config X86_INTEL_TSX_MODE_OFF
1915 TSX is disabled if possible - equals to tsx=off command line parameter.
1917 config X86_INTEL_TSX_MODE_ON
1920 TSX is always enabled on TSX capable HW - equals the tsx=on command
1923 config X86_INTEL_TSX_MODE_AUTO
1926 TSX is enabled on TSX capable HW that is believed to be safe against
1927 side channel attacks- equals the tsx=auto command line parameter.
1931 bool "Software Guard eXtensions (SGX)"
1932 depends on X86_64 && CPU_SUP_INTEL
1934 depends on CRYPTO_SHA256=y
1937 select NUMA_KEEP_MEMINFO if NUMA
1940 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1941 that can be used by applications to set aside private regions of code
1942 and data, referred to as enclaves. An enclave's private memory can
1943 only be accessed by code running within the enclave. Accesses from
1944 outside the enclave, including other enclaves, are disallowed by
1950 bool "EFI runtime service support"
1953 select EFI_RUNTIME_WRAPPERS
1954 select ARCH_USE_MEMREMAP_PROT
1956 This enables the kernel to use EFI runtime services that are
1957 available (such as the EFI variable services).
1959 This option is only useful on systems that have EFI firmware.
1960 In addition, you should use the latest ELILO loader available
1961 at <http://elilo.sourceforge.net> in order to take advantage
1962 of EFI runtime services. However, even with this option, the
1963 resultant kernel should continue to boot on existing non-EFI
1967 bool "EFI stub support"
1969 depends on $(cc-option,-mabi=ms) || X86_32
1972 This kernel feature allows a bzImage to be loaded directly
1973 by EFI firmware without the use of a bootloader.
1975 See Documentation/admin-guide/efi-stub.rst for more information.
1978 bool "EFI mixed-mode support"
1979 depends on EFI_STUB && X86_64
1981 Enabling this feature allows a 64-bit kernel to be booted
1982 on a 32-bit firmware, provided that your CPU supports 64-bit
1985 Note that it is not possible to boot a mixed-mode enabled
1986 kernel via the EFI boot stub - a bootloader that supports
1987 the EFI handover protocol must be used.
1991 source "kernel/Kconfig.hz"
1994 bool "kexec system call"
1997 kexec is a system call that implements the ability to shutdown your
1998 current kernel, and to start another kernel. It is like a reboot
1999 but it is independent of the system firmware. And like a reboot
2000 you can start any kernel with it, not just Linux.
2002 The name comes from the similarity to the exec system call.
2004 It is an ongoing process to be certain the hardware in a machine
2005 is properly shutdown, so do not be surprised if this code does not
2006 initially work for you. As of this writing the exact hardware
2007 interface is strongly in flux, so no good recommendation can be
2011 bool "kexec file based system call"
2016 depends on CRYPTO_SHA256=y
2018 This is new version of kexec system call. This system call is
2019 file based and takes file descriptors as system call argument
2020 for kernel and initramfs as opposed to list of segments as
2021 accepted by previous system call.
2023 config ARCH_HAS_KEXEC_PURGATORY
2027 bool "Verify kernel signature during kexec_file_load() syscall"
2028 depends on KEXEC_FILE
2031 This option makes the kexec_file_load() syscall check for a valid
2032 signature of the kernel image. The image can still be loaded without
2033 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2034 there's a signature that we can check, then it must be valid.
2036 In addition to this option, you need to enable signature
2037 verification for the corresponding kernel image type being
2038 loaded in order for this to work.
2040 config KEXEC_SIG_FORCE
2041 bool "Require a valid signature in kexec_file_load() syscall"
2042 depends on KEXEC_SIG
2044 This option makes kernel signature verification mandatory for
2045 the kexec_file_load() syscall.
2047 config KEXEC_BZIMAGE_VERIFY_SIG
2048 bool "Enable bzImage signature verification support"
2049 depends on KEXEC_SIG
2050 depends on SIGNED_PE_FILE_VERIFICATION
2051 select SYSTEM_TRUSTED_KEYRING
2053 Enable bzImage signature verification support.
2056 bool "kernel crash dumps"
2057 depends on X86_64 || (X86_32 && HIGHMEM)
2059 Generate crash dump after being started by kexec.
2060 This should be normally only set in special crash dump kernels
2061 which are loaded in the main kernel with kexec-tools into
2062 a specially reserved region and then later executed after
2063 a crash by kdump/kexec. The crash dump kernel must be compiled
2064 to a memory address not used by the main kernel or BIOS using
2065 PHYSICAL_START, or it must be built as a relocatable image
2066 (CONFIG_RELOCATABLE=y).
2067 For more details see Documentation/admin-guide/kdump/kdump.rst
2071 depends on KEXEC && HIBERNATION
2073 Jump between original kernel and kexeced kernel and invoke
2074 code in physical address mode via KEXEC
2076 config PHYSICAL_START
2077 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2080 This gives the physical address where the kernel is loaded.
2082 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2083 bzImage will decompress itself to above physical address and
2084 run from there. Otherwise, bzImage will run from the address where
2085 it has been loaded by the boot loader and will ignore above physical
2088 In normal kdump cases one does not have to set/change this option
2089 as now bzImage can be compiled as a completely relocatable image
2090 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2091 address. This option is mainly useful for the folks who don't want
2092 to use a bzImage for capturing the crash dump and want to use a
2093 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2094 to be specifically compiled to run from a specific memory area
2095 (normally a reserved region) and this option comes handy.
2097 So if you are using bzImage for capturing the crash dump,
2098 leave the value here unchanged to 0x1000000 and set
2099 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2100 for capturing the crash dump change this value to start of
2101 the reserved region. In other words, it can be set based on
2102 the "X" value as specified in the "crashkernel=YM@XM"
2103 command line boot parameter passed to the panic-ed
2104 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2105 for more details about crash dumps.
2107 Usage of bzImage for capturing the crash dump is recommended as
2108 one does not have to build two kernels. Same kernel can be used
2109 as production kernel and capture kernel. Above option should have
2110 gone away after relocatable bzImage support is introduced. But it
2111 is present because there are users out there who continue to use
2112 vmlinux for dump capture. This option should go away down the
2115 Don't change this unless you know what you are doing.
2118 bool "Build a relocatable kernel"
2121 This builds a kernel image that retains relocation information
2122 so it can be loaded someplace besides the default 1MB.
2123 The relocations tend to make the kernel binary about 10% larger,
2124 but are discarded at runtime.
2126 One use is for the kexec on panic case where the recovery kernel
2127 must live at a different physical address than the primary
2130 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2131 it has been loaded at and the compile time physical address
2132 (CONFIG_PHYSICAL_START) is used as the minimum location.
2134 config RANDOMIZE_BASE
2135 bool "Randomize the address of the kernel image (KASLR)"
2136 depends on RELOCATABLE
2139 In support of Kernel Address Space Layout Randomization (KASLR),
2140 this randomizes the physical address at which the kernel image
2141 is decompressed and the virtual address where the kernel
2142 image is mapped, as a security feature that deters exploit
2143 attempts relying on knowledge of the location of kernel
2146 On 64-bit, the kernel physical and virtual addresses are
2147 randomized separately. The physical address will be anywhere
2148 between 16MB and the top of physical memory (up to 64TB). The
2149 virtual address will be randomized from 16MB up to 1GB (9 bits
2150 of entropy). Note that this also reduces the memory space
2151 available to kernel modules from 1.5GB to 1GB.
2153 On 32-bit, the kernel physical and virtual addresses are
2154 randomized together. They will be randomized from 16MB up to
2155 512MB (8 bits of entropy).
2157 Entropy is generated using the RDRAND instruction if it is
2158 supported. If RDTSC is supported, its value is mixed into
2159 the entropy pool as well. If neither RDRAND nor RDTSC are
2160 supported, then entropy is read from the i8254 timer. The
2161 usable entropy is limited by the kernel being built using
2162 2GB addressing, and that PHYSICAL_ALIGN must be at a
2163 minimum of 2MB. As a result, only 10 bits of entropy are
2164 theoretically possible, but the implementations are further
2165 limited due to memory layouts.
2169 # Relocation on x86 needs some additional build support
2170 config X86_NEED_RELOCS
2172 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2174 config PHYSICAL_ALIGN
2175 hex "Alignment value to which kernel should be aligned"
2177 range 0x2000 0x1000000 if X86_32
2178 range 0x200000 0x1000000 if X86_64
2180 This value puts the alignment restrictions on physical address
2181 where kernel is loaded and run from. Kernel is compiled for an
2182 address which meets above alignment restriction.
2184 If bootloader loads the kernel at a non-aligned address and
2185 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2186 address aligned to above value and run from there.
2188 If bootloader loads the kernel at a non-aligned address and
2189 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2190 load address and decompress itself to the address it has been
2191 compiled for and run from there. The address for which kernel is
2192 compiled already meets above alignment restrictions. Hence the
2193 end result is that kernel runs from a physical address meeting
2194 above alignment restrictions.
2196 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2197 this value must be a multiple of 0x200000.
2199 Don't change this unless you know what you are doing.
2201 config DYNAMIC_MEMORY_LAYOUT
2204 This option makes base addresses of vmalloc and vmemmap as well as
2205 __PAGE_OFFSET movable during boot.
2207 config RANDOMIZE_MEMORY
2208 bool "Randomize the kernel memory sections"
2210 depends on RANDOMIZE_BASE
2211 select DYNAMIC_MEMORY_LAYOUT
2212 default RANDOMIZE_BASE
2214 Randomizes the base virtual address of kernel memory sections
2215 (physical memory mapping, vmalloc & vmemmap). This security feature
2216 makes exploits relying on predictable memory locations less reliable.
2218 The order of allocations remains unchanged. Entropy is generated in
2219 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2220 configuration have in average 30,000 different possible virtual
2221 addresses for each memory section.
2225 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2226 hex "Physical memory mapping padding" if EXPERT
2227 depends on RANDOMIZE_MEMORY
2228 default "0xa" if MEMORY_HOTPLUG
2230 range 0x1 0x40 if MEMORY_HOTPLUG
2233 Define the padding in terabytes added to the existing physical
2234 memory size during kernel memory randomization. It is useful
2235 for memory hotplug support but reduces the entropy available for
2236 address randomization.
2238 If unsure, leave at the default value.
2244 config BOOTPARAM_HOTPLUG_CPU0
2245 bool "Set default setting of cpu0_hotpluggable"
2246 depends on HOTPLUG_CPU
2248 Set whether default state of cpu0_hotpluggable is on or off.
2250 Say Y here to enable CPU0 hotplug by default. If this switch
2251 is turned on, there is no need to give cpu0_hotplug kernel
2252 parameter and the CPU0 hotplug feature is enabled by default.
2254 Please note: there are two known CPU0 dependencies if you want
2255 to enable the CPU0 hotplug feature either by this switch or by
2256 cpu0_hotplug kernel parameter.
2258 First, resume from hibernate or suspend always starts from CPU0.
2259 So hibernate and suspend are prevented if CPU0 is offline.
2261 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2262 offline if any interrupt can not migrate out of CPU0. There may
2263 be other CPU0 dependencies.
2265 Please make sure the dependencies are under your control before
2266 you enable this feature.
2268 Say N if you don't want to enable CPU0 hotplug feature by default.
2269 You still can enable the CPU0 hotplug feature at boot by kernel
2270 parameter cpu0_hotplug.
2272 config DEBUG_HOTPLUG_CPU0
2274 prompt "Debug CPU0 hotplug"
2275 depends on HOTPLUG_CPU
2277 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2278 soon as possible and boots up userspace with CPU0 offlined. User
2279 can online CPU0 back after boot time.
2281 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2282 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2283 compilation or giving cpu0_hotplug kernel parameter at boot.
2289 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2290 depends on COMPAT_32
2292 Certain buggy versions of glibc will crash if they are
2293 presented with a 32-bit vDSO that is not mapped at the address
2294 indicated in its segment table.
2296 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2297 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2298 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2299 the only released version with the bug, but OpenSUSE 9
2300 contains a buggy "glibc 2.3.2".
2302 The symptom of the bug is that everything crashes on startup, saying:
2303 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2305 Saying Y here changes the default value of the vdso32 boot
2306 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2307 This works around the glibc bug but hurts performance.
2309 If unsure, say N: if you are compiling your own kernel, you
2310 are unlikely to be using a buggy version of glibc.
2313 prompt "vsyscall table for legacy applications"
2315 default LEGACY_VSYSCALL_XONLY
2317 Legacy user code that does not know how to find the vDSO expects
2318 to be able to issue three syscalls by calling fixed addresses in
2319 kernel space. Since this location is not randomized with ASLR,
2320 it can be used to assist security vulnerability exploitation.
2322 This setting can be changed at boot time via the kernel command
2323 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2324 is deprecated and can only be enabled using the kernel command
2327 On a system with recent enough glibc (2.14 or newer) and no
2328 static binaries, you can say None without a performance penalty
2329 to improve security.
2331 If unsure, select "Emulate execution only".
2333 config LEGACY_VSYSCALL_XONLY
2334 bool "Emulate execution only"
2336 The kernel traps and emulates calls into the fixed vsyscall
2337 address mapping and does not allow reads. This
2338 configuration is recommended when userspace might use the
2339 legacy vsyscall area but support for legacy binary
2340 instrumentation of legacy code is not needed. It mitigates
2341 certain uses of the vsyscall area as an ASLR-bypassing
2344 config LEGACY_VSYSCALL_NONE
2347 There will be no vsyscall mapping at all. This will
2348 eliminate any risk of ASLR bypass due to the vsyscall
2349 fixed address mapping. Attempts to use the vsyscalls
2350 will be reported to dmesg, so that either old or
2351 malicious userspace programs can be identified.
2356 bool "Built-in kernel command line"
2358 Allow for specifying boot arguments to the kernel at
2359 build time. On some systems (e.g. embedded ones), it is
2360 necessary or convenient to provide some or all of the
2361 kernel boot arguments with the kernel itself (that is,
2362 to not rely on the boot loader to provide them.)
2364 To compile command line arguments into the kernel,
2365 set this option to 'Y', then fill in the
2366 boot arguments in CONFIG_CMDLINE.
2368 Systems with fully functional boot loaders (i.e. non-embedded)
2369 should leave this option set to 'N'.
2372 string "Built-in kernel command string"
2373 depends on CMDLINE_BOOL
2376 Enter arguments here that should be compiled into the kernel
2377 image and used at boot time. If the boot loader provides a
2378 command line at boot time, it is appended to this string to
2379 form the full kernel command line, when the system boots.
2381 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2382 change this behavior.
2384 In most cases, the command line (whether built-in or provided
2385 by the boot loader) should specify the device for the root
2388 config CMDLINE_OVERRIDE
2389 bool "Built-in command line overrides boot loader arguments"
2390 depends on CMDLINE_BOOL && CMDLINE != ""
2392 Set this option to 'Y' to have the kernel ignore the boot loader
2393 command line, and use ONLY the built-in command line.
2395 This is used to work around broken boot loaders. This should
2396 be set to 'N' under normal conditions.
2398 config MODIFY_LDT_SYSCALL
2399 bool "Enable the LDT (local descriptor table)" if EXPERT
2402 Linux can allow user programs to install a per-process x86
2403 Local Descriptor Table (LDT) using the modify_ldt(2) system
2404 call. This is required to run 16-bit or segmented code such as
2405 DOSEMU or some Wine programs. It is also used by some very old
2406 threading libraries.
2408 Enabling this feature adds a small amount of overhead to
2409 context switches and increases the low-level kernel attack
2410 surface. Disabling it removes the modify_ldt(2) system call.
2412 Saying 'N' here may make sense for embedded or server kernels.
2414 config STRICT_SIGALTSTACK_SIZE
2415 bool "Enforce strict size checking for sigaltstack"
2416 depends on DYNAMIC_SIGFRAME
2418 For historical reasons MINSIGSTKSZ is a constant which became
2419 already too small with AVX512 support. Add a mechanism to
2420 enforce strict checking of the sigaltstack size against the
2421 real size of the FPU frame. This option enables the check
2422 by default. It can also be controlled via the kernel command
2423 line option 'strict_sas_size' independent of this config
2424 switch. Enabling it might break existing applications which
2425 allocate a too small sigaltstack but 'work' because they
2426 never get a signal delivered.
2428 Say 'N' unless you want to really enforce this check.
2430 source "kernel/livepatch/Kconfig"
2435 def_bool $(cc-option,-mharden-sls=all)
2437 config CC_HAS_RETURN_THUNK
2438 def_bool $(cc-option,-mfunction-return=thunk-extern)
2440 menuconfig SPECULATION_MITIGATIONS
2441 bool "Mitigations for speculative execution vulnerabilities"
2444 Say Y here to enable options which enable mitigations for
2445 speculative execution hardware vulnerabilities.
2447 If you say N, all mitigations will be disabled. You really
2448 should know what you are doing to say so.
2450 if SPECULATION_MITIGATIONS
2452 config PAGE_TABLE_ISOLATION
2453 bool "Remove the kernel mapping in user mode"
2455 depends on (X86_64 || X86_PAE)
2457 This feature reduces the number of hardware side channels by
2458 ensuring that the majority of kernel addresses are not mapped
2461 See Documentation/x86/pti.rst for more details.
2464 bool "Avoid speculative indirect branches in kernel"
2465 select OBJTOOL if HAVE_OBJTOOL
2468 Compile kernel with the retpoline compiler options to guard against
2469 kernel-to-user data leaks by avoiding speculative indirect
2470 branches. Requires a compiler with -mindirect-branch=thunk-extern
2471 support for full protection. The kernel may run slower.
2474 bool "Enable return-thunks"
2475 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2476 select OBJTOOL if HAVE_OBJTOOL
2479 Compile the kernel with the return-thunks compiler option to guard
2480 against kernel-to-user data leaks by avoiding return speculation.
2481 Requires a compiler with -mfunction-return=thunk-extern
2482 support for full protection. The kernel may run slower.
2484 config CPU_UNRET_ENTRY
2485 bool "Enable UNRET on kernel entry"
2486 depends on CPU_SUP_AMD && RETHUNK && X86_64
2489 Compile the kernel with support for the retbleed=unret mitigation.
2491 config CPU_IBPB_ENTRY
2492 bool "Enable IBPB on kernel entry"
2493 depends on CPU_SUP_AMD && X86_64
2496 Compile the kernel with support for the retbleed=ibpb mitigation.
2498 config CPU_IBRS_ENTRY
2499 bool "Enable IBRS on kernel entry"
2500 depends on CPU_SUP_INTEL && X86_64
2503 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2504 This mitigates both spectre_v2 and retbleed at great cost to
2508 bool "Mitigate Straight-Line-Speculation"
2509 depends on CC_HAS_SLS && X86_64
2510 select OBJTOOL if HAVE_OBJTOOL
2513 Compile the kernel with straight-line-speculation options to guard
2514 against straight line speculation. The kernel image might be slightly
2519 config ARCH_HAS_ADD_PAGES
2521 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2523 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2526 menu "Power management and ACPI options"
2528 config ARCH_HIBERNATION_HEADER
2530 depends on HIBERNATION
2532 source "kernel/power/Kconfig"
2534 source "drivers/acpi/Kconfig"
2541 tristate "APM (Advanced Power Management) BIOS support"
2542 depends on X86_32 && PM_SLEEP
2544 APM is a BIOS specification for saving power using several different
2545 techniques. This is mostly useful for battery powered laptops with
2546 APM compliant BIOSes. If you say Y here, the system time will be
2547 reset after a RESUME operation, the /proc/apm device will provide
2548 battery status information, and user-space programs will receive
2549 notification of APM "events" (e.g. battery status change).
2551 If you select "Y" here, you can disable actual use of the APM
2552 BIOS by passing the "apm=off" option to the kernel at boot time.
2554 Note that the APM support is almost completely disabled for
2555 machines with more than one CPU.
2557 In order to use APM, you will need supporting software. For location
2558 and more information, read <file:Documentation/power/apm-acpi.rst>
2559 and the Battery Powered Linux mini-HOWTO, available from
2560 <http://www.tldp.org/docs.html#howto>.
2562 This driver does not spin down disk drives (see the hdparm(8)
2563 manpage ("man 8 hdparm") for that), and it doesn't turn off
2564 VESA-compliant "green" monitors.
2566 This driver does not support the TI 4000M TravelMate and the ACER
2567 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2568 desktop machines also don't have compliant BIOSes, and this driver
2569 may cause those machines to panic during the boot phase.
2571 Generally, if you don't have a battery in your machine, there isn't
2572 much point in using this driver and you should say N. If you get
2573 random kernel OOPSes or reboots that don't seem to be related to
2574 anything, try disabling/enabling this option (or disabling/enabling
2577 Some other things you should try when experiencing seemingly random,
2580 1) make sure that you have enough swap space and that it is
2582 2) pass the "no-hlt" option to the kernel
2583 3) switch on floating point emulation in the kernel and pass
2584 the "no387" option to the kernel
2585 4) pass the "floppy=nodma" option to the kernel
2586 5) pass the "mem=4M" option to the kernel (thereby disabling
2587 all but the first 4 MB of RAM)
2588 6) make sure that the CPU is not over clocked.
2589 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2590 8) disable the cache from your BIOS settings
2591 9) install a fan for the video card or exchange video RAM
2592 10) install a better fan for the CPU
2593 11) exchange RAM chips
2594 12) exchange the motherboard.
2596 To compile this driver as a module, choose M here: the
2597 module will be called apm.
2601 config APM_IGNORE_USER_SUSPEND
2602 bool "Ignore USER SUSPEND"
2604 This option will ignore USER SUSPEND requests. On machines with a
2605 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2606 series notebooks, it is necessary to say Y because of a BIOS bug.
2608 config APM_DO_ENABLE
2609 bool "Enable PM at boot time"
2611 Enable APM features at boot time. From page 36 of the APM BIOS
2612 specification: "When disabled, the APM BIOS does not automatically
2613 power manage devices, enter the Standby State, enter the Suspend
2614 State, or take power saving steps in response to CPU Idle calls."
2615 This driver will make CPU Idle calls when Linux is idle (unless this
2616 feature is turned off -- see "Do CPU IDLE calls", below). This
2617 should always save battery power, but more complicated APM features
2618 will be dependent on your BIOS implementation. You may need to turn
2619 this option off if your computer hangs at boot time when using APM
2620 support, or if it beeps continuously instead of suspending. Turn
2621 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2622 T400CDT. This is off by default since most machines do fine without
2627 bool "Make CPU Idle calls when idle"
2629 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2630 On some machines, this can activate improved power savings, such as
2631 a slowed CPU clock rate, when the machine is idle. These idle calls
2632 are made after the idle loop has run for some length of time (e.g.,
2633 333 mS). On some machines, this will cause a hang at boot time or
2634 whenever the CPU becomes idle. (On machines with more than one CPU,
2635 this option does nothing.)
2637 config APM_DISPLAY_BLANK
2638 bool "Enable console blanking using APM"
2640 Enable console blanking using the APM. Some laptops can use this to
2641 turn off the LCD backlight when the screen blanker of the Linux
2642 virtual console blanks the screen. Note that this is only used by
2643 the virtual console screen blanker, and won't turn off the backlight
2644 when using the X Window system. This also doesn't have anything to
2645 do with your VESA-compliant power-saving monitor. Further, this
2646 option doesn't work for all laptops -- it might not turn off your
2647 backlight at all, or it might print a lot of errors to the console,
2648 especially if you are using gpm.
2650 config APM_ALLOW_INTS
2651 bool "Allow interrupts during APM BIOS calls"
2653 Normally we disable external interrupts while we are making calls to
2654 the APM BIOS as a measure to lessen the effects of a badly behaving
2655 BIOS implementation. The BIOS should reenable interrupts if it
2656 needs to. Unfortunately, some BIOSes do not -- especially those in
2657 many of the newer IBM Thinkpads. If you experience hangs when you
2658 suspend, try setting this to Y. Otherwise, say N.
2662 source "drivers/cpufreq/Kconfig"
2664 source "drivers/cpuidle/Kconfig"
2666 source "drivers/idle/Kconfig"
2670 menu "Bus options (PCI etc.)"
2673 prompt "PCI access mode"
2674 depends on X86_32 && PCI
2677 On PCI systems, the BIOS can be used to detect the PCI devices and
2678 determine their configuration. However, some old PCI motherboards
2679 have BIOS bugs and may crash if this is done. Also, some embedded
2680 PCI-based systems don't have any BIOS at all. Linux can also try to
2681 detect the PCI hardware directly without using the BIOS.
2683 With this option, you can specify how Linux should detect the
2684 PCI devices. If you choose "BIOS", the BIOS will be used,
2685 if you choose "Direct", the BIOS won't be used, and if you
2686 choose "MMConfig", then PCI Express MMCONFIG will be used.
2687 If you choose "Any", the kernel will try MMCONFIG, then the
2688 direct access method and falls back to the BIOS if that doesn't
2689 work. If unsure, go with the default, which is "Any".
2694 config PCI_GOMMCONFIG
2711 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2713 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2716 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2719 bool "Support mmconfig PCI config space access" if X86_64
2721 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2722 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2726 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2730 depends on PCI && XEN
2732 config MMCONF_FAM10H
2734 depends on X86_64 && PCI_MMCONFIG && ACPI
2736 config PCI_CNB20LE_QUIRK
2737 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2740 Read the PCI windows out of the CNB20LE host bridge. This allows
2741 PCI hotplug to work on systems with the CNB20LE chipset which do
2744 There's no public spec for this chipset, and this functionality
2745 is known to be incomplete.
2747 You should say N unless you know you need this.
2750 bool "ISA bus support on modern systems" if EXPERT
2752 Expose ISA bus device drivers and options available for selection and
2753 configuration. Enable this option if your target machine has an ISA
2754 bus. ISA is an older system, displaced by PCI and newer bus
2755 architectures -- if your target machine is modern, it probably does
2756 not have an ISA bus.
2760 # x86_64 have no ISA slots, but can have ISA-style DMA.
2762 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2765 Enables ISA-style DMA support for devices requiring such controllers.
2773 Find out whether you have ISA slots on your motherboard. ISA is the
2774 name of a bus system, i.e. the way the CPU talks to the other stuff
2775 inside your box. Other bus systems are PCI, EISA, MicroChannel
2776 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2777 newer boards don't support it. If you have ISA, say Y, otherwise N.
2780 tristate "NatSemi SCx200 support"
2782 This provides basic support for National Semiconductor's
2783 (now AMD's) Geode processors. The driver probes for the
2784 PCI-IDs of several on-chip devices, so its a good dependency
2785 for other scx200_* drivers.
2787 If compiled as a module, the driver is named scx200.
2789 config SCx200HR_TIMER
2790 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2794 This driver provides a clocksource built upon the on-chip
2795 27MHz high-resolution timer. Its also a workaround for
2796 NSC Geode SC-1100's buggy TSC, which loses time when the
2797 processor goes idle (as is done by the scheduler). The
2798 other workaround is idle=poll boot option.
2801 bool "One Laptop Per Child support"
2809 Add support for detecting the unique features of the OLPC
2813 bool "OLPC XO-1 Power Management"
2814 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2816 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2819 bool "OLPC XO-1 Real Time Clock"
2820 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2822 Add support for the XO-1 real time clock, which can be used as a
2823 programmable wakeup source.
2826 bool "OLPC XO-1 SCI extras"
2827 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2831 Add support for SCI-based features of the OLPC XO-1 laptop:
2832 - EC-driven system wakeups
2836 - AC adapter status updates
2837 - Battery status updates
2839 config OLPC_XO15_SCI
2840 bool "OLPC XO-1.5 SCI extras"
2841 depends on OLPC && ACPI
2844 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2845 - EC-driven system wakeups
2846 - AC adapter status updates
2847 - Battery status updates
2850 bool "PCEngines ALIX System Support (LED setup)"
2853 This option enables system support for the PCEngines ALIX.
2854 At present this just sets up LEDs for GPIO control on
2855 ALIX2/3/6 boards. However, other system specific setup should
2858 Note: You must still enable the drivers for GPIO and LED support
2859 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2861 Note: You have to set alix.force=1 for boards with Award BIOS.
2864 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2867 This option enables system support for the Soekris Engineering net5501.
2870 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2874 This option enables system support for the Traverse Technologies GEOS.
2877 bool "Technologic Systems TS-5500 platform support"
2879 select CHECK_SIGNATURE
2883 This option enables system support for the Technologic Systems TS-5500.
2889 depends on CPU_SUP_AMD && PCI
2893 menu "Binary Emulations"
2895 config IA32_EMULATION
2896 bool "IA32 Emulation"
2898 select ARCH_WANT_OLD_COMPAT_IPC
2900 select COMPAT_OLD_SIGACTION
2902 Include code to run legacy 32-bit programs under a
2903 64-bit kernel. You should likely turn this on, unless you're
2904 100% sure that you don't have any 32-bit programs left.
2907 bool "x32 ABI for 64-bit mode"
2909 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2910 # compressed debug sections to x86_x32 properly:
2911 # https://github.com/ClangBuiltLinux/linux/issues/514
2912 # https://github.com/ClangBuiltLinux/linux/issues/1141
2913 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2915 Include code to run binaries for the x32 native 32-bit ABI
2916 for 64-bit processors. An x32 process gets access to the
2917 full 64-bit register file and wide data path while leaving
2918 pointers at 32 bits for smaller memory footprint.
2922 depends on IA32_EMULATION || X86_32
2924 select OLD_SIGSUSPEND3
2928 depends on IA32_EMULATION || X86_X32_ABI
2930 config COMPAT_FOR_U64_ALIGNMENT
2936 config HAVE_ATOMIC_IOMAP
2940 source "arch/x86/kvm/Kconfig"
2942 source "arch/x86/Kconfig.assembler"