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_SUPPORTS_PER_VMA_LOCK
31 select ARCH_USE_CMPXCHG_LOCKREF
32 select HAVE_ARCH_SOFT_DIRTY
33 select MODULES_USE_ELF_RELA
34 select NEED_DMA_MAP_STATE
36 select ARCH_HAS_ELFCORE_COMPAT
39 config FORCE_DYNAMIC_FTRACE
42 depends on FUNCTION_TRACER
45 We keep the static function tracing (!DYNAMIC_FTRACE) around
46 in order to test the non static function tracing in the
47 generic code, as other architectures still use it. But we
48 only need to keep it around for x86_64. No need to keep it
49 for x86_32. For x86_32, force DYNAMIC_FTRACE.
53 # ( Note that options that are marked 'if X86_64' could in principle be
54 # ported to 32-bit as well. )
59 # Note: keep this list sorted alphabetically
61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
63 select ARCH_32BIT_OFF_T if X86_32
64 select ARCH_CLOCKSOURCE_INIT
65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
72 select ARCH_HAS_CACHE_LINE_SIZE
73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
74 select ARCH_HAS_CPU_FINALIZE_INIT
75 select ARCH_HAS_CURRENT_STACK_POINTER
76 select ARCH_HAS_DEBUG_VIRTUAL
77 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
78 select ARCH_HAS_DEVMEM_IS_ALLOWED
79 select ARCH_HAS_EARLY_DEBUG if KGDB
80 select ARCH_HAS_ELF_RANDOMIZE
81 select ARCH_HAS_FAST_MULTIPLIER
82 select ARCH_HAS_FORTIFY_SOURCE
83 select ARCH_HAS_GCOV_PROFILE_ALL
84 select ARCH_HAS_KCOV if X86_64
85 select ARCH_HAS_MEM_ENCRYPT
86 select ARCH_HAS_MEMBARRIER_SYNC_CORE
87 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
88 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
89 select ARCH_HAS_PMEM_API if X86_64
90 select ARCH_HAS_PTE_DEVMAP if X86_64
91 select ARCH_HAS_PTE_SPECIAL
92 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
93 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
94 select ARCH_HAS_COPY_MC if X86_64
95 select ARCH_HAS_SET_MEMORY
96 select ARCH_HAS_SET_DIRECT_MAP
97 select ARCH_HAS_STRICT_KERNEL_RWX
98 select ARCH_HAS_STRICT_MODULE_RWX
99 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
100 select ARCH_HAS_SYSCALL_WRAPPER
101 select ARCH_HAS_UBSAN_SANITIZE_ALL
102 select ARCH_HAS_DEBUG_WX
103 select ARCH_HAS_ZONE_DMA_SET if EXPERT
104 select ARCH_HAVE_NMI_SAFE_CMPXCHG
105 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
106 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
107 select ARCH_MIGHT_HAVE_PC_PARPORT
108 select ARCH_MIGHT_HAVE_PC_SERIO
109 select ARCH_STACKWALK
110 select ARCH_SUPPORTS_ACPI
111 select ARCH_SUPPORTS_ATOMIC_RMW
112 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
113 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
114 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
115 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
116 select ARCH_SUPPORTS_CFI_CLANG if X86_64
117 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
118 select ARCH_SUPPORTS_LTO_CLANG
119 select ARCH_SUPPORTS_LTO_CLANG_THIN
120 select ARCH_USE_BUILTIN_BSWAP
121 select ARCH_USE_MEMTEST
122 select ARCH_USE_QUEUED_RWLOCKS
123 select ARCH_USE_QUEUED_SPINLOCKS
124 select ARCH_USE_SYM_ANNOTATIONS
125 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
126 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
127 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
128 select ARCH_WANTS_NO_INSTR
129 select ARCH_WANT_GENERAL_HUGETLB
130 select ARCH_WANT_HUGE_PMD_SHARE
131 select ARCH_WANT_LD_ORPHAN_WARN
132 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
133 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
134 select ARCH_WANTS_THP_SWAP if X86_64
135 select ARCH_HAS_PARANOID_L1D_FLUSH
136 select BUILDTIME_TABLE_SORT
138 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
139 select CLOCKSOURCE_WATCHDOG
140 # Word-size accesses may read uninitialized data past the trailing \0
141 # in strings and cause false KMSAN reports.
142 select DCACHE_WORD_ACCESS if !KMSAN
143 select DYNAMIC_SIGFRAME
144 select EDAC_ATOMIC_SCRUB
146 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
147 select GENERIC_CLOCKEVENTS_MIN_ADJUST
148 select GENERIC_CMOS_UPDATE
149 select GENERIC_CPU_AUTOPROBE
150 select GENERIC_CPU_VULNERABILITIES
151 select GENERIC_EARLY_IOREMAP
154 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
155 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
156 select GENERIC_IRQ_MIGRATION if SMP
157 select GENERIC_IRQ_PROBE
158 select GENERIC_IRQ_RESERVATION_MODE
159 select GENERIC_IRQ_SHOW
160 select GENERIC_PENDING_IRQ if SMP
161 select GENERIC_PTDUMP
162 select GENERIC_SMP_IDLE_THREAD
163 select GENERIC_TIME_VSYSCALL
164 select GENERIC_GETTIMEOFDAY
165 select GENERIC_VDSO_TIME_NS
166 select GUP_GET_PXX_LOW_HIGH if X86_PAE
167 select HARDIRQS_SW_RESEND
168 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
170 select HAVE_ACPI_APEI if ACPI
171 select HAVE_ACPI_APEI_NMI if ACPI
172 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
173 select HAVE_ARCH_AUDITSYSCALL
174 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
175 select HAVE_ARCH_HUGE_VMALLOC if X86_64
176 select HAVE_ARCH_JUMP_LABEL
177 select HAVE_ARCH_JUMP_LABEL_RELATIVE
178 select HAVE_ARCH_KASAN if X86_64
179 select HAVE_ARCH_KASAN_VMALLOC if X86_64
180 select HAVE_ARCH_KFENCE
181 select HAVE_ARCH_KMSAN if X86_64
182 select HAVE_ARCH_KGDB
183 select HAVE_ARCH_MMAP_RND_BITS if MMU
184 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
185 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
186 select HAVE_ARCH_PREL32_RELOCATIONS
187 select HAVE_ARCH_SECCOMP_FILTER
188 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
189 select HAVE_ARCH_STACKLEAK
190 select HAVE_ARCH_TRACEHOOK
191 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
192 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
193 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
194 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
195 select HAVE_ARCH_VMAP_STACK if X86_64
196 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
197 select HAVE_ARCH_WITHIN_STACK_FRAMES
198 select HAVE_ASM_MODVERSIONS
199 select HAVE_CMPXCHG_DOUBLE
200 select HAVE_CMPXCHG_LOCAL
201 select HAVE_CONTEXT_TRACKING_USER if X86_64
202 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
203 select HAVE_C_RECORDMCOUNT
204 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
205 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
206 select HAVE_BUILDTIME_MCOUNT_SORT
207 select HAVE_DEBUG_KMEMLEAK
208 select HAVE_DMA_CONTIGUOUS
209 select HAVE_DYNAMIC_FTRACE
210 select HAVE_DYNAMIC_FTRACE_WITH_REGS
211 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
212 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
213 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
214 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
216 select HAVE_EFFICIENT_UNALIGNED_ACCESS
218 select HAVE_EXIT_THREAD
220 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
221 select HAVE_FTRACE_MCOUNT_RECORD
222 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
223 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
224 select HAVE_FUNCTION_TRACER
225 select HAVE_GCC_PLUGINS
226 select HAVE_HW_BREAKPOINT
227 select HAVE_IOREMAP_PROT
228 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
229 select HAVE_IRQ_TIME_ACCOUNTING
230 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
231 select HAVE_KERNEL_BZIP2
232 select HAVE_KERNEL_GZIP
233 select HAVE_KERNEL_LZ4
234 select HAVE_KERNEL_LZMA
235 select HAVE_KERNEL_LZO
236 select HAVE_KERNEL_XZ
237 select HAVE_KERNEL_ZSTD
239 select HAVE_KPROBES_ON_FTRACE
240 select HAVE_FUNCTION_ERROR_INJECTION
241 select HAVE_KRETPROBES
244 select HAVE_LIVEPATCH if X86_64
245 select HAVE_MIXED_BREAKPOINTS_REGS
246 select HAVE_MOD_ARCH_SPECIFIC
249 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
251 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
252 select HAVE_OBJTOOL if X86_64
253 select HAVE_OPTPROBES
254 select HAVE_PCSPKR_PLATFORM
255 select HAVE_PERF_EVENTS
256 select HAVE_PERF_EVENTS_NMI
257 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
259 select HAVE_PERF_REGS
260 select HAVE_PERF_USER_STACK_DUMP
261 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
262 select MMU_GATHER_MERGE_VMAS
263 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
264 select HAVE_REGS_AND_STACK_ACCESS_API
265 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
266 select HAVE_FUNCTION_ARG_ACCESS_API
267 select HAVE_SETUP_PER_CPU_AREA
268 select HAVE_SOFTIRQ_ON_OWN_STACK
269 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
270 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
271 select HAVE_STATIC_CALL
272 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
273 select HAVE_PREEMPT_DYNAMIC_CALL
275 select HAVE_RUST if X86_64
276 select HAVE_SYSCALL_TRACEPOINTS
277 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
278 select HAVE_UNSTABLE_SCHED_CLOCK
279 select HAVE_USER_RETURN_NOTIFIER
280 select HAVE_GENERIC_VDSO
281 select HOTPLUG_PARALLEL if SMP && X86_64
282 select HOTPLUG_SMT if SMP
283 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
284 select IRQ_FORCED_THREADING
285 select LOCK_MM_AND_FIND_VMA
286 select NEED_PER_CPU_EMBED_FIRST_CHUNK
287 select NEED_PER_CPU_PAGE_FIRST_CHUNK
288 select NEED_SG_DMA_LENGTH
289 select PCI_DOMAINS if PCI
290 select PCI_LOCKLESS_CONFIG if PCI
293 select RTC_MC146818_LIB
295 select SYSCTL_EXCEPTION_TRACE
296 select THREAD_INFO_IN_TASK
297 select TRACE_IRQFLAGS_SUPPORT
298 select TRACE_IRQFLAGS_NMI_SUPPORT
299 select USER_STACKTRACE_SUPPORT
300 select HAVE_ARCH_KCSAN if X86_64
301 select PROC_PID_ARCH_STATUS if PROC_FS
302 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
303 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
304 select FUNCTION_ALIGNMENT_4B
305 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
306 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
308 config INSTRUCTION_DECODER
310 depends on KPROBES || PERF_EVENTS || UPROBES
314 default "elf32-i386" if X86_32
315 default "elf64-x86-64" if X86_64
317 config LOCKDEP_SUPPORT
320 config STACKTRACE_SUPPORT
326 config ARCH_MMAP_RND_BITS_MIN
330 config ARCH_MMAP_RND_BITS_MAX
334 config ARCH_MMAP_RND_COMPAT_BITS_MIN
337 config ARCH_MMAP_RND_COMPAT_BITS_MAX
343 config GENERIC_ISA_DMA
345 depends on ISA_DMA_API
349 default y if KMSAN || KASAN
354 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
356 config GENERIC_BUG_RELATIVE_POINTERS
359 config ARCH_MAY_HAVE_PC_FDC
361 depends on ISA_DMA_API
363 config GENERIC_CALIBRATE_DELAY
366 config ARCH_HAS_CPU_RELAX
369 config ARCH_HIBERNATION_POSSIBLE
372 config ARCH_SUSPEND_POSSIBLE
378 config KASAN_SHADOW_OFFSET
381 default 0xdffffc0000000000
383 config HAVE_INTEL_TXT
385 depends on INTEL_IOMMU && ACPI
389 depends on X86_32 && SMP
393 depends on X86_64 && SMP
395 config ARCH_SUPPORTS_UPROBES
398 config FIX_EARLYCON_MEM
401 config DYNAMIC_PHYSICAL_MASK
404 config PGTABLE_LEVELS
406 default 5 if X86_5LEVEL
411 config CC_HAS_SANE_STACKPROTECTOR
413 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
414 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
416 We have to make sure stack protector is unconditionally disabled if
417 the compiler produces broken code or if it does not let us control
418 the segment on 32-bit kernels.
420 menu "Processor type and features"
423 bool "Symmetric multi-processing support"
425 This enables support for systems with more than one CPU. If you have
426 a system with only one CPU, say N. If you have a system with more
429 If you say N here, the kernel will run on uni- and multiprocessor
430 machines, but will use only one CPU of a multiprocessor machine. If
431 you say Y here, the kernel will run on many, but not all,
432 uniprocessor machines. On a uniprocessor machine, the kernel
433 will run faster if you say N here.
435 Note that if you say Y here and choose architecture "586" or
436 "Pentium" under "Processor family", the kernel will not work on 486
437 architectures. Similarly, multiprocessor kernels for the "PPro"
438 architecture may not work on all Pentium based boards.
440 People using multiprocessor machines who say Y here should also say
441 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
442 Management" code will be disabled if you say Y here.
444 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
445 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
446 <http://www.tldp.org/docs.html#howto>.
448 If you don't know what to do here, say N.
451 bool "Support x2apic"
452 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
454 This enables x2apic support on CPUs that have this feature.
456 This allows 32-bit apic IDs (so it can support very large systems),
457 and accesses the local apic via MSRs not via mmio.
459 Some Intel systems circa 2022 and later are locked into x2APIC mode
460 and can not fall back to the legacy APIC modes if SGX or TDX are
461 enabled in the BIOS. They will boot with very reduced functionality
462 without enabling this option.
464 If you don't know what to do here, say N.
467 bool "Enable MPS table" if ACPI
469 depends on X86_LOCAL_APIC
471 For old smp systems that do not have proper acpi support. Newer systems
472 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
476 depends on X86_GOLDFISH
478 config X86_CPU_RESCTRL
479 bool "x86 CPU resource control support"
480 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
482 select PROC_CPU_RESCTRL if PROC_FS
484 Enable x86 CPU resource control support.
486 Provide support for the allocation and monitoring of system resources
489 Intel calls this Intel Resource Director Technology
490 (Intel(R) RDT). More information about RDT can be found in the
491 Intel x86 Architecture Software Developer Manual.
493 AMD calls this AMD Platform Quality of Service (AMD QoS).
494 More information about AMD QoS can be found in the AMD64 Technology
495 Platform Quality of Service Extensions manual.
501 bool "Support for big SMP systems with more than 8 CPUs"
504 This option is needed for the systems that have more than 8 CPUs.
506 config X86_EXTENDED_PLATFORM
507 bool "Support for extended (non-PC) x86 platforms"
510 If you disable this option then the kernel will only support
511 standard PC platforms. (which covers the vast majority of
514 If you enable this option then you'll be able to select support
515 for the following (non-PC) 32 bit x86 platforms:
516 Goldfish (Android emulator)
519 SGI 320/540 (Visual Workstation)
520 STA2X11-based (e.g. Northville)
521 Moorestown MID devices
523 If you have one of these systems, or if you want to build a
524 generic distribution kernel, say Y here - otherwise say N.
528 config X86_EXTENDED_PLATFORM
529 bool "Support for extended (non-PC) x86 platforms"
532 If you disable this option then the kernel will only support
533 standard PC platforms. (which covers the vast majority of
536 If you enable this option then you'll be able to select support
537 for the following (non-PC) 64 bit x86 platforms:
542 If you have one of these systems, or if you want to build a
543 generic distribution kernel, say Y here - otherwise say N.
545 # This is an alphabetically sorted list of 64 bit extended platforms
546 # Please maintain the alphabetic order if and when there are additions
548 bool "Numascale NumaChip"
550 depends on X86_EXTENDED_PLATFORM
553 depends on X86_X2APIC
554 depends on PCI_MMCONFIG
556 Adds support for Numascale NumaChip large-SMP systems. Needed to
557 enable more than ~168 cores.
558 If you don't have one of these, you should say N here.
562 select HYPERVISOR_GUEST
564 depends on X86_64 && PCI
565 depends on X86_EXTENDED_PLATFORM
568 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
569 supposed to run on these EM64T-based machines. Only choose this option
570 if you have one of these machines.
573 bool "SGI Ultraviolet"
575 depends on X86_EXTENDED_PLATFORM
578 depends on KEXEC_CORE
579 depends on X86_X2APIC
582 This option is needed in order to support SGI Ultraviolet systems.
583 If you don't have one of these, you should say N here.
585 # Following is an alphabetically sorted list of 32 bit extended platforms
586 # Please maintain the alphabetic order if and when there are additions
589 bool "Goldfish (Virtual Platform)"
590 depends on X86_EXTENDED_PLATFORM
592 Enable support for the Goldfish virtual platform used primarily
593 for Android development. Unless you are building for the Android
594 Goldfish emulator say N here.
597 bool "CE4100 TV platform"
599 depends on PCI_GODIRECT
600 depends on X86_IO_APIC
602 depends on X86_EXTENDED_PLATFORM
603 select X86_REBOOTFIXUPS
605 select OF_EARLY_FLATTREE
607 Select for the Intel CE media processor (CE4100) SOC.
608 This option compiles in support for the CE4100 SOC for settop
609 boxes and media devices.
612 bool "Intel MID platform support"
613 depends on X86_EXTENDED_PLATFORM
614 depends on X86_PLATFORM_DEVICES
616 depends on X86_64 || (PCI_GOANY && X86_32)
617 depends on X86_IO_APIC
622 Select to build a kernel capable of supporting Intel MID (Mobile
623 Internet Device) platform systems which do not have the PCI legacy
624 interfaces. If you are building for a PC class system say N here.
626 Intel MID platforms are based on an Intel processor and chipset which
627 consume less power than most of the x86 derivatives.
629 config X86_INTEL_QUARK
630 bool "Intel Quark platform support"
632 depends on X86_EXTENDED_PLATFORM
633 depends on X86_PLATFORM_DEVICES
637 depends on X86_IO_APIC
642 Select to include support for Quark X1000 SoC.
643 Say Y here if you have a Quark based system such as the Arduino
644 compatible Intel Galileo.
646 config X86_INTEL_LPSS
647 bool "Intel Low Power Subsystem Support"
648 depends on X86 && ACPI && PCI
653 Select to build support for Intel Low Power Subsystem such as
654 found on Intel Lynxpoint PCH. Selecting this option enables
655 things like clock tree (common clock framework) and pincontrol
656 which are needed by the LPSS peripheral drivers.
658 config X86_AMD_PLATFORM_DEVICE
659 bool "AMD ACPI2Platform devices support"
664 Select to interpret AMD specific ACPI device to platform device
665 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
666 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
667 implemented under PINCTRL subsystem.
670 tristate "Intel SoC IOSF Sideband support for SoC platforms"
673 This option enables sideband register access support for Intel SoC
674 platforms. On these platforms the IOSF sideband is used in lieu of
675 MSR's for some register accesses, mostly but not limited to thermal
676 and power. Drivers may query the availability of this device to
677 determine if they need the sideband in order to work on these
678 platforms. The sideband is available on the following SoC products.
679 This list is not meant to be exclusive.
684 You should say Y if you are running a kernel on one of these SoC's.
686 config IOSF_MBI_DEBUG
687 bool "Enable IOSF sideband access through debugfs"
688 depends on IOSF_MBI && DEBUG_FS
690 Select this option to expose the IOSF sideband access registers (MCR,
691 MDR, MCRX) through debugfs to write and read register information from
692 different units on the SoC. This is most useful for obtaining device
693 state information for debug and analysis. As this is a general access
694 mechanism, users of this option would have specific knowledge of the
695 device they want to access.
697 If you don't require the option or are in doubt, say N.
700 bool "RDC R-321x SoC"
702 depends on X86_EXTENDED_PLATFORM
704 select X86_REBOOTFIXUPS
706 This option is needed for RDC R-321x system-on-chip, also known
708 If you don't have one of these chips, you should say N here.
710 config X86_32_NON_STANDARD
711 bool "Support non-standard 32-bit SMP architectures"
712 depends on X86_32 && SMP
713 depends on X86_EXTENDED_PLATFORM
715 This option compiles in the bigsmp and STA2X11 default
716 subarchitectures. It is intended for a generic binary
717 kernel. If you select them all, kernel will probe it one by
718 one and will fallback to default.
720 # Alphabetically sorted list of Non standard 32 bit platforms
722 config X86_SUPPORTS_MEMORY_FAILURE
724 # MCE code calls memory_failure():
726 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
727 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
728 depends on X86_64 || !SPARSEMEM
729 select ARCH_SUPPORTS_MEMORY_FAILURE
732 bool "STA2X11 Companion Chip Support"
733 depends on X86_32_NON_STANDARD && PCI
738 This adds support for boards based on the STA2X11 IO-Hub,
739 a.k.a. "ConneXt". The chip is used in place of the standard
740 PC chipset, so all "standard" peripherals are missing. If this
741 option is selected the kernel will still be able to boot on
742 standard PC machines.
745 tristate "Eurobraille/Iris poweroff module"
748 The Iris machines from EuroBraille do not have APM or ACPI support
749 to shut themselves down properly. A special I/O sequence is
750 needed to do so, which is what this module does at
753 This is only for Iris machines from EuroBraille.
757 config SCHED_OMIT_FRAME_POINTER
759 prompt "Single-depth WCHAN output"
762 Calculate simpler /proc/<PID>/wchan values. If this option
763 is disabled then wchan values will recurse back to the
764 caller function. This provides more accurate wchan values,
765 at the expense of slightly more scheduling overhead.
767 If in doubt, say "Y".
769 menuconfig HYPERVISOR_GUEST
770 bool "Linux guest support"
772 Say Y here to enable options for running Linux under various hyper-
773 visors. This option enables basic hypervisor detection and platform
776 If you say N, all options in this submenu will be skipped and
777 disabled, and Linux guest support won't be built in.
782 bool "Enable paravirtualization code"
783 depends on HAVE_STATIC_CALL
785 This changes the kernel so it can modify itself when it is run
786 under a hypervisor, potentially improving performance significantly
787 over full virtualization. However, when run without a hypervisor
788 the kernel is theoretically slower and slightly larger.
793 config PARAVIRT_DEBUG
794 bool "paravirt-ops debugging"
795 depends on PARAVIRT && DEBUG_KERNEL
797 Enable to debug paravirt_ops internals. Specifically, BUG if
798 a paravirt_op is missing when it is called.
800 config PARAVIRT_SPINLOCKS
801 bool "Paravirtualization layer for spinlocks"
802 depends on PARAVIRT && SMP
804 Paravirtualized spinlocks allow a pvops backend to replace the
805 spinlock implementation with something virtualization-friendly
806 (for example, block the virtual CPU rather than spinning).
808 It has a minimal impact on native kernels and gives a nice performance
809 benefit on paravirtualized KVM / Xen kernels.
811 If you are unsure how to answer this question, answer Y.
813 config X86_HV_CALLBACK_VECTOR
816 source "arch/x86/xen/Kconfig"
819 bool "KVM Guest support (including kvmclock)"
821 select PARAVIRT_CLOCK
822 select ARCH_CPUIDLE_HALTPOLL
823 select X86_HV_CALLBACK_VECTOR
826 This option enables various optimizations for running under the KVM
827 hypervisor. It includes a paravirtualized clock, so that instead
828 of relying on a PIT (or probably other) emulation by the
829 underlying device model, the host provides the guest with
830 timing infrastructure such as time of day, and system time
832 config ARCH_CPUIDLE_HALTPOLL
834 prompt "Disable host haltpoll when loading haltpoll driver"
836 If virtualized under KVM, disable host haltpoll.
839 bool "Support for running PVH guests"
841 This option enables the PVH entry point for guest virtual machines
842 as specified in the x86/HVM direct boot ABI.
844 config PARAVIRT_TIME_ACCOUNTING
845 bool "Paravirtual steal time accounting"
848 Select this option to enable fine granularity task steal time
849 accounting. Time spent executing other tasks in parallel with
850 the current vCPU is discounted from the vCPU power. To account for
851 that, there can be a small performance impact.
853 If in doubt, say N here.
855 config PARAVIRT_CLOCK
858 config JAILHOUSE_GUEST
859 bool "Jailhouse non-root cell support"
860 depends on X86_64 && PCI
863 This option allows to run Linux as guest in a Jailhouse non-root
864 cell. You can leave this option disabled if you only want to start
865 Jailhouse and run Linux afterwards in the root cell.
868 bool "ACRN Guest support"
870 select X86_HV_CALLBACK_VECTOR
872 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
873 a flexible, lightweight reference open-source hypervisor, built with
874 real-time and safety-criticality in mind. It is built for embedded
875 IOT with small footprint and real-time features. More details can be
876 found in https://projectacrn.org/.
878 config INTEL_TDX_GUEST
879 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
880 depends on X86_64 && CPU_SUP_INTEL
881 depends on X86_X2APIC
883 select ARCH_HAS_CC_PLATFORM
884 select X86_MEM_ENCRYPT
886 select UNACCEPTED_MEMORY
888 Support running as a guest under Intel TDX. Without this support,
889 the guest kernel can not boot or run under TDX.
890 TDX includes memory encryption and integrity capabilities
891 which protect the confidentiality and integrity of guest
892 memory contents and CPU state. TDX guests are protected from
893 some attacks from the VMM.
895 endif # HYPERVISOR_GUEST
897 source "arch/x86/Kconfig.cpu"
901 prompt "HPET Timer Support" if X86_32
903 Use the IA-PC HPET (High Precision Event Timer) to manage
904 time in preference to the PIT and RTC, if a HPET is
906 HPET is the next generation timer replacing legacy 8254s.
907 The HPET provides a stable time base on SMP
908 systems, unlike the TSC, but it is more expensive to access,
909 as it is off-chip. The interface used is documented
910 in the HPET spec, revision 1.
912 You can safely choose Y here. However, HPET will only be
913 activated if the platform and the BIOS support this feature.
914 Otherwise the 8254 will be used for timing services.
916 Choose N to continue using the legacy 8254 timer.
918 config HPET_EMULATE_RTC
920 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
922 # Mark as expert because too many people got it wrong.
923 # The code disables itself when not needed.
926 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
927 bool "Enable DMI scanning" if EXPERT
929 Enabled scanning of DMI to identify machine quirks. Say Y
930 here unless you have verified that your setup is not
931 affected by entries in the DMI blacklist. Required by PNP
935 bool "Old AMD GART IOMMU support"
939 depends on X86_64 && PCI && AMD_NB
941 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
942 GART based hardware IOMMUs.
944 The GART supports full DMA access for devices with 32-bit access
945 limitations, on systems with more than 3 GB. This is usually needed
946 for USB, sound, many IDE/SATA chipsets and some other devices.
948 Newer systems typically have a modern AMD IOMMU, supported via
949 the CONFIG_AMD_IOMMU=y config option.
951 In normal configurations this driver is only active when needed:
952 there's more than 3 GB of memory and the system contains a
953 32-bit limited device.
957 config BOOT_VESA_SUPPORT
960 If true, at least one selected framebuffer driver can take advantage
961 of VESA video modes set at an early boot stage via the vga= parameter.
964 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
965 depends on X86_64 && SMP && DEBUG_KERNEL
966 select CPUMASK_OFFSTACK
968 Enable maximum number of CPUS and NUMA Nodes for this architecture.
972 # The maximum number of CPUs supported:
974 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
975 # and which can be configured interactively in the
976 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
978 # The ranges are different on 32-bit and 64-bit kernels, depending on
979 # hardware capabilities and scalability features of the kernel.
981 # ( If MAXSMP is enabled we just use the highest possible value and disable
982 # interactive configuration. )
985 config NR_CPUS_RANGE_BEGIN
987 default NR_CPUS_RANGE_END if MAXSMP
991 config NR_CPUS_RANGE_END
994 default 64 if SMP && X86_BIGSMP
995 default 8 if SMP && !X86_BIGSMP
998 config NR_CPUS_RANGE_END
1001 default 8192 if SMP && CPUMASK_OFFSTACK
1002 default 512 if SMP && !CPUMASK_OFFSTACK
1005 config NR_CPUS_DEFAULT
1008 default 32 if X86_BIGSMP
1012 config NR_CPUS_DEFAULT
1015 default 8192 if MAXSMP
1020 int "Maximum number of CPUs" if SMP && !MAXSMP
1021 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1022 default NR_CPUS_DEFAULT
1024 This allows you to specify the maximum number of CPUs which this
1025 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1026 supported value is 8192, otherwise the maximum value is 512. The
1027 minimum value which makes sense is 2.
1029 This is purely to save memory: each supported CPU adds about 8KB
1030 to the kernel image.
1032 config SCHED_CLUSTER
1033 bool "Cluster scheduler support"
1037 Cluster scheduler support improves the CPU scheduler's decision
1038 making when dealing with machines that have clusters of CPUs.
1039 Cluster usually means a couple of CPUs which are placed closely
1040 by sharing mid-level caches, last-level cache tags or internal
1048 prompt "Multi-core scheduler support"
1051 Multi-core scheduler support improves the CPU scheduler's decision
1052 making when dealing with multi-core CPU chips at a cost of slightly
1053 increased overhead in some places. If unsure say N here.
1055 config SCHED_MC_PRIO
1056 bool "CPU core priorities scheduler support"
1057 depends on SCHED_MC && CPU_SUP_INTEL
1058 select X86_INTEL_PSTATE
1062 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1063 core ordering determined at manufacturing time, which allows
1064 certain cores to reach higher turbo frequencies (when running
1065 single threaded workloads) than others.
1067 Enabling this kernel feature teaches the scheduler about
1068 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1069 scheduler's CPU selection logic accordingly, so that higher
1070 overall system performance can be achieved.
1072 This feature will have no effect on CPUs without this feature.
1074 If unsure say Y here.
1078 depends on !SMP && X86_LOCAL_APIC
1081 bool "Local APIC support on uniprocessors" if !PCI_MSI
1083 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1085 A local APIC (Advanced Programmable Interrupt Controller) is an
1086 integrated interrupt controller in the CPU. If you have a single-CPU
1087 system which has a processor with a local APIC, you can say Y here to
1088 enable and use it. If you say Y here even though your machine doesn't
1089 have a local APIC, then the kernel will still run with no slowdown at
1090 all. The local APIC supports CPU-generated self-interrupts (timer,
1091 performance counters), and the NMI watchdog which detects hard
1094 config X86_UP_IOAPIC
1095 bool "IO-APIC support on uniprocessors"
1096 depends on X86_UP_APIC
1098 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1099 SMP-capable replacement for PC-style interrupt controllers. Most
1100 SMP systems and many recent uniprocessor systems have one.
1102 If you have a single-CPU system with an IO-APIC, you can say Y here
1103 to use it. If you say Y here even though your machine doesn't have
1104 an IO-APIC, then the kernel will still run with no slowdown at all.
1106 config X86_LOCAL_APIC
1108 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1109 select IRQ_DOMAIN_HIERARCHY
1113 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1115 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1116 bool "Reroute for broken boot IRQs"
1117 depends on X86_IO_APIC
1119 This option enables a workaround that fixes a source of
1120 spurious interrupts. This is recommended when threaded
1121 interrupt handling is used on systems where the generation of
1122 superfluous "boot interrupts" cannot be disabled.
1124 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1125 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1126 kernel does during interrupt handling). On chipsets where this
1127 boot IRQ generation cannot be disabled, this workaround keeps
1128 the original IRQ line masked so that only the equivalent "boot
1129 IRQ" is delivered to the CPUs. The workaround also tells the
1130 kernel to set up the IRQ handler on the boot IRQ line. In this
1131 way only one interrupt is delivered to the kernel. Otherwise
1132 the spurious second interrupt may cause the kernel to bring
1133 down (vital) interrupt lines.
1135 Only affects "broken" chipsets. Interrupt sharing may be
1136 increased on these systems.
1139 bool "Machine Check / overheating reporting"
1140 select GENERIC_ALLOCATOR
1143 Machine Check support allows the processor to notify the
1144 kernel if it detects a problem (e.g. overheating, data corruption).
1145 The action the kernel takes depends on the severity of the problem,
1146 ranging from warning messages to halting the machine.
1148 config X86_MCELOG_LEGACY
1149 bool "Support for deprecated /dev/mcelog character device"
1152 Enable support for /dev/mcelog which is needed by the old mcelog
1153 userspace logging daemon. Consider switching to the new generation
1156 config X86_MCE_INTEL
1158 prompt "Intel MCE features"
1159 depends on X86_MCE && X86_LOCAL_APIC
1161 Additional support for intel specific MCE features such as
1162 the thermal monitor.
1166 prompt "AMD MCE features"
1167 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1169 Additional support for AMD specific MCE features such as
1170 the DRAM Error Threshold.
1172 config X86_ANCIENT_MCE
1173 bool "Support for old Pentium 5 / WinChip machine checks"
1174 depends on X86_32 && X86_MCE
1176 Include support for machine check handling on old Pentium 5 or WinChip
1177 systems. These typically need to be enabled explicitly on the command
1180 config X86_MCE_THRESHOLD
1181 depends on X86_MCE_AMD || X86_MCE_INTEL
1184 config X86_MCE_INJECT
1185 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1186 tristate "Machine check injector support"
1188 Provide support for injecting machine checks for testing purposes.
1189 If you don't know what a machine check is and you don't do kernel
1190 QA it is safe to say n.
1192 source "arch/x86/events/Kconfig"
1194 config X86_LEGACY_VM86
1195 bool "Legacy VM86 support"
1198 This option allows user programs to put the CPU into V8086
1199 mode, which is an 80286-era approximation of 16-bit real mode.
1201 Some very old versions of X and/or vbetool require this option
1202 for user mode setting. Similarly, DOSEMU will use it if
1203 available to accelerate real mode DOS programs. However, any
1204 recent version of DOSEMU, X, or vbetool should be fully
1205 functional even without kernel VM86 support, as they will all
1206 fall back to software emulation. Nevertheless, if you are using
1207 a 16-bit DOS program where 16-bit performance matters, vm86
1208 mode might be faster than emulation and you might want to
1211 Note that any app that works on a 64-bit kernel is unlikely to
1212 need this option, as 64-bit kernels don't, and can't, support
1213 V8086 mode. This option is also unrelated to 16-bit protected
1214 mode and is not needed to run most 16-bit programs under Wine.
1216 Enabling this option increases the complexity of the kernel
1217 and slows down exception handling a tiny bit.
1219 If unsure, say N here.
1223 default X86_LEGACY_VM86
1226 bool "Enable support for 16-bit segments" if EXPERT
1228 depends on MODIFY_LDT_SYSCALL
1230 This option is required by programs like Wine to run 16-bit
1231 protected mode legacy code on x86 processors. Disabling
1232 this option saves about 300 bytes on i386, or around 6K text
1233 plus 16K runtime memory on x86-64,
1237 depends on X86_16BIT && X86_32
1241 depends on X86_16BIT && X86_64
1243 config X86_VSYSCALL_EMULATION
1244 bool "Enable vsyscall emulation" if EXPERT
1248 This enables emulation of the legacy vsyscall page. Disabling
1249 it is roughly equivalent to booting with vsyscall=none, except
1250 that it will also disable the helpful warning if a program
1251 tries to use a vsyscall. With this option set to N, offending
1252 programs will just segfault, citing addresses of the form
1255 This option is required by many programs built before 2013, and
1256 care should be used even with newer programs if set to N.
1258 Disabling this option saves about 7K of kernel size and
1259 possibly 4K of additional runtime pagetable memory.
1261 config X86_IOPL_IOPERM
1262 bool "IOPERM and IOPL Emulation"
1265 This enables the ioperm() and iopl() syscalls which are necessary
1266 for legacy applications.
1268 Legacy IOPL support is an overbroad mechanism which allows user
1269 space aside of accessing all 65536 I/O ports also to disable
1270 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1271 capabilities and permission from potentially active security
1274 The emulation restricts the functionality of the syscall to
1275 only allowing the full range I/O port access, but prevents the
1276 ability to disable interrupts from user space which would be
1277 granted if the hardware IOPL mechanism would be used.
1280 tristate "Toshiba Laptop support"
1283 This adds a driver to safely access the System Management Mode of
1284 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1285 not work on models with a Phoenix BIOS. The System Management Mode
1286 is used to set the BIOS and power saving options on Toshiba portables.
1288 For information on utilities to make use of this driver see the
1289 Toshiba Linux utilities web site at:
1290 <http://www.buzzard.org.uk/toshiba/>.
1292 Say Y if you intend to run this kernel on a Toshiba portable.
1295 config X86_REBOOTFIXUPS
1296 bool "Enable X86 board specific fixups for reboot"
1299 This enables chipset and/or board specific fixups to be done
1300 in order to get reboot to work correctly. This is only needed on
1301 some combinations of hardware and BIOS. The symptom, for which
1302 this config is intended, is when reboot ends with a stalled/hung
1305 Currently, the only fixup is for the Geode machines using
1306 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1308 Say Y if you want to enable the fixup. Currently, it's safe to
1309 enable this option even if you don't need it.
1314 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1316 config MICROCODE_LATE_LOADING
1317 bool "Late microcode loading (DANGEROUS)"
1319 depends on MICROCODE
1321 Loading microcode late, when the system is up and executing instructions
1322 is a tricky business and should be avoided if possible. Just the sequence
1323 of synchronizing all cores and SMT threads is one fragile dance which does
1324 not guarantee that cores might not softlock after the loading. Therefore,
1325 use this at your own risk. Late loading taints the kernel too.
1328 tristate "/dev/cpu/*/msr - Model-specific register support"
1330 This device gives privileged processes access to the x86
1331 Model-Specific Registers (MSRs). It is a character device with
1332 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1333 MSR accesses are directed to a specific CPU on multi-processor
1337 tristate "/dev/cpu/*/cpuid - CPU information support"
1339 This device gives processes access to the x86 CPUID instruction to
1340 be executed on a specific processor. It is a character device
1341 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1345 prompt "High Memory Support"
1352 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1353 However, the address space of 32-bit x86 processors is only 4
1354 Gigabytes large. That means that, if you have a large amount of
1355 physical memory, not all of it can be "permanently mapped" by the
1356 kernel. The physical memory that's not permanently mapped is called
1359 If you are compiling a kernel which will never run on a machine with
1360 more than 1 Gigabyte total physical RAM, answer "off" here (default
1361 choice and suitable for most users). This will result in a "3GB/1GB"
1362 split: 3GB are mapped so that each process sees a 3GB virtual memory
1363 space and the remaining part of the 4GB virtual memory space is used
1364 by the kernel to permanently map as much physical memory as
1367 If the machine has between 1 and 4 Gigabytes physical RAM, then
1370 If more than 4 Gigabytes is used then answer "64GB" here. This
1371 selection turns Intel PAE (Physical Address Extension) mode on.
1372 PAE implements 3-level paging on IA32 processors. PAE is fully
1373 supported by Linux, PAE mode is implemented on all recent Intel
1374 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1375 then the kernel will not boot on CPUs that don't support PAE!
1377 The actual amount of total physical memory will either be
1378 auto detected or can be forced by using a kernel command line option
1379 such as "mem=256M". (Try "man bootparam" or see the documentation of
1380 your boot loader (lilo or loadlin) about how to pass options to the
1381 kernel at boot time.)
1383 If unsure, say "off".
1388 Select this if you have a 32-bit processor and between 1 and 4
1389 gigabytes of physical RAM.
1393 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1396 Select this if you have a 32-bit processor and more than 4
1397 gigabytes of physical RAM.
1402 prompt "Memory split" if EXPERT
1406 Select the desired split between kernel and user memory.
1408 If the address range available to the kernel is less than the
1409 physical memory installed, the remaining memory will be available
1410 as "high memory". Accessing high memory is a little more costly
1411 than low memory, as it needs to be mapped into the kernel first.
1412 Note that increasing the kernel address space limits the range
1413 available to user programs, making the address space there
1414 tighter. Selecting anything other than the default 3G/1G split
1415 will also likely make your kernel incompatible with binary-only
1418 If you are not absolutely sure what you are doing, leave this
1422 bool "3G/1G user/kernel split"
1423 config VMSPLIT_3G_OPT
1425 bool "3G/1G user/kernel split (for full 1G low memory)"
1427 bool "2G/2G user/kernel split"
1428 config VMSPLIT_2G_OPT
1430 bool "2G/2G user/kernel split (for full 2G low memory)"
1432 bool "1G/3G user/kernel split"
1437 default 0xB0000000 if VMSPLIT_3G_OPT
1438 default 0x80000000 if VMSPLIT_2G
1439 default 0x78000000 if VMSPLIT_2G_OPT
1440 default 0x40000000 if VMSPLIT_1G
1446 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1449 bool "PAE (Physical Address Extension) Support"
1450 depends on X86_32 && !HIGHMEM4G
1451 select PHYS_ADDR_T_64BIT
1454 PAE is required for NX support, and furthermore enables
1455 larger swapspace support for non-overcommit purposes. It
1456 has the cost of more pagetable lookup overhead, and also
1457 consumes more pagetable space per process.
1460 bool "Enable 5-level page tables support"
1462 select DYNAMIC_MEMORY_LAYOUT
1463 select SPARSEMEM_VMEMMAP
1466 5-level paging enables access to larger address space:
1467 up to 128 PiB of virtual address space and 4 PiB of
1468 physical address space.
1470 It will be supported by future Intel CPUs.
1472 A kernel with the option enabled can be booted on machines that
1473 support 4- or 5-level paging.
1475 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1480 config X86_DIRECT_GBPAGES
1484 Certain kernel features effectively disable kernel
1485 linear 1 GB mappings (even if the CPU otherwise
1486 supports them), so don't confuse the user by printing
1487 that we have them enabled.
1489 config X86_CPA_STATISTICS
1490 bool "Enable statistic for Change Page Attribute"
1493 Expose statistics about the Change Page Attribute mechanism, which
1494 helps to determine the effectiveness of preserving large and huge
1495 page mappings when mapping protections are changed.
1497 config X86_MEM_ENCRYPT
1498 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1499 select DYNAMIC_PHYSICAL_MASK
1502 config AMD_MEM_ENCRYPT
1503 bool "AMD Secure Memory Encryption (SME) support"
1504 depends on X86_64 && CPU_SUP_AMD
1506 select DMA_COHERENT_POOL
1507 select ARCH_USE_MEMREMAP_PROT
1508 select INSTRUCTION_DECODER
1509 select ARCH_HAS_CC_PLATFORM
1510 select X86_MEM_ENCRYPT
1511 select UNACCEPTED_MEMORY
1513 Say yes to enable support for the encryption of system memory.
1514 This requires an AMD processor that supports Secure Memory
1517 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1518 bool "Activate AMD Secure Memory Encryption (SME) by default"
1519 depends on AMD_MEM_ENCRYPT
1521 Say yes to have system memory encrypted by default if running on
1522 an AMD processor that supports Secure Memory Encryption (SME).
1524 If set to Y, then the encryption of system memory can be
1525 deactivated with the mem_encrypt=off command line option.
1527 If set to N, then the encryption of system memory can be
1528 activated with the mem_encrypt=on command line option.
1530 # Common NUMA Features
1532 bool "NUMA Memory Allocation and Scheduler Support"
1534 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1535 default y if X86_BIGSMP
1536 select USE_PERCPU_NUMA_NODE_ID
1538 Enable NUMA (Non-Uniform Memory Access) support.
1540 The kernel will try to allocate memory used by a CPU on the
1541 local memory controller of the CPU and add some more
1542 NUMA awareness to the kernel.
1544 For 64-bit this is recommended if the system is Intel Core i7
1545 (or later), AMD Opteron, or EM64T NUMA.
1547 For 32-bit this is only needed if you boot a 32-bit
1548 kernel on a 64-bit NUMA platform.
1550 Otherwise, you should say N.
1554 prompt "Old style AMD Opteron NUMA detection"
1555 depends on X86_64 && NUMA && PCI
1557 Enable AMD NUMA node topology detection. You should say Y here if
1558 you have a multi processor AMD system. This uses an old method to
1559 read the NUMA configuration directly from the builtin Northbridge
1560 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1561 which also takes priority if both are compiled in.
1563 config X86_64_ACPI_NUMA
1565 prompt "ACPI NUMA detection"
1566 depends on X86_64 && NUMA && ACPI && PCI
1569 Enable ACPI SRAT based node topology detection.
1572 bool "NUMA emulation"
1575 Enable NUMA emulation. A flat machine will be split
1576 into virtual nodes when booted with "numa=fake=N", where N is the
1577 number of nodes. This is only useful for debugging.
1580 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1582 default "10" if MAXSMP
1583 default "6" if X86_64
1587 Specify the maximum number of NUMA Nodes available on the target
1588 system. Increases memory reserved to accommodate various tables.
1590 config ARCH_FLATMEM_ENABLE
1592 depends on X86_32 && !NUMA
1594 config ARCH_SPARSEMEM_ENABLE
1596 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1597 select SPARSEMEM_STATIC if X86_32
1598 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1600 config ARCH_SPARSEMEM_DEFAULT
1601 def_bool X86_64 || (NUMA && X86_32)
1603 config ARCH_SELECT_MEMORY_MODEL
1605 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1607 config ARCH_MEMORY_PROBE
1608 bool "Enable sysfs memory/probe interface"
1609 depends on MEMORY_HOTPLUG
1611 This option enables a sysfs memory/probe interface for testing.
1612 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1613 If you are unsure how to answer this question, answer N.
1615 config ARCH_PROC_KCORE_TEXT
1617 depends on X86_64 && PROC_KCORE
1619 config ILLEGAL_POINTER_VALUE
1622 default 0xdead000000000000 if X86_64
1624 config X86_PMEM_LEGACY_DEVICE
1627 config X86_PMEM_LEGACY
1628 tristate "Support non-standard NVDIMMs and ADR protected memory"
1629 depends on PHYS_ADDR_T_64BIT
1631 select X86_PMEM_LEGACY_DEVICE
1632 select NUMA_KEEP_MEMINFO if NUMA
1635 Treat memory marked using the non-standard e820 type of 12 as used
1636 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1637 The kernel will offer these regions to the 'pmem' driver so
1638 they can be used for persistent storage.
1643 bool "Allocate 3rd-level pagetables from highmem"
1646 The VM uses one page table entry for each page of physical memory.
1647 For systems with a lot of RAM, this can be wasteful of precious
1648 low memory. Setting this option will put user-space page table
1649 entries in high memory.
1651 config X86_CHECK_BIOS_CORRUPTION
1652 bool "Check for low memory corruption"
1654 Periodically check for memory corruption in low memory, which
1655 is suspected to be caused by BIOS. Even when enabled in the
1656 configuration, it is disabled at runtime. Enable it by
1657 setting "memory_corruption_check=1" on the kernel command
1658 line. By default it scans the low 64k of memory every 60
1659 seconds; see the memory_corruption_check_size and
1660 memory_corruption_check_period parameters in
1661 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1663 When enabled with the default parameters, this option has
1664 almost no overhead, as it reserves a relatively small amount
1665 of memory and scans it infrequently. It both detects corruption
1666 and prevents it from affecting the running system.
1668 It is, however, intended as a diagnostic tool; if repeatable
1669 BIOS-originated corruption always affects the same memory,
1670 you can use memmap= to prevent the kernel from using that
1673 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1674 bool "Set the default setting of memory_corruption_check"
1675 depends on X86_CHECK_BIOS_CORRUPTION
1678 Set whether the default state of memory_corruption_check is
1681 config MATH_EMULATION
1683 depends on MODIFY_LDT_SYSCALL
1684 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1686 Linux can emulate a math coprocessor (used for floating point
1687 operations) if you don't have one. 486DX and Pentium processors have
1688 a math coprocessor built in, 486SX and 386 do not, unless you added
1689 a 487DX or 387, respectively. (The messages during boot time can
1690 give you some hints here ["man dmesg"].) Everyone needs either a
1691 coprocessor or this emulation.
1693 If you don't have a math coprocessor, you need to say Y here; if you
1694 say Y here even though you have a coprocessor, the coprocessor will
1695 be used nevertheless. (This behavior can be changed with the kernel
1696 command line option "no387", which comes handy if your coprocessor
1697 is broken. Try "man bootparam" or see the documentation of your boot
1698 loader (lilo or loadlin) about how to pass options to the kernel at
1699 boot time.) This means that it is a good idea to say Y here if you
1700 intend to use this kernel on different machines.
1702 More information about the internals of the Linux math coprocessor
1703 emulation can be found in <file:arch/x86/math-emu/README>.
1705 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1706 kernel, it won't hurt.
1710 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1712 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1713 the Memory Type Range Registers (MTRRs) may be used to control
1714 processor access to memory ranges. This is most useful if you have
1715 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1716 allows bus write transfers to be combined into a larger transfer
1717 before bursting over the PCI/AGP bus. This can increase performance
1718 of image write operations 2.5 times or more. Saying Y here creates a
1719 /proc/mtrr file which may be used to manipulate your processor's
1720 MTRRs. Typically the X server should use this.
1722 This code has a reasonably generic interface so that similar
1723 control registers on other processors can be easily supported
1726 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1727 Registers (ARRs) which provide a similar functionality to MTRRs. For
1728 these, the ARRs are used to emulate the MTRRs.
1729 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1730 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1731 write-combining. All of these processors are supported by this code
1732 and it makes sense to say Y here if you have one of them.
1734 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1735 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1736 can lead to all sorts of problems, so it's good to say Y here.
1738 You can safely say Y even if your machine doesn't have MTRRs, you'll
1739 just add about 9 KB to your kernel.
1741 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1743 config MTRR_SANITIZER
1745 prompt "MTRR cleanup support"
1748 Convert MTRR layout from continuous to discrete, so X drivers can
1749 add writeback entries.
1751 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1752 The largest mtrr entry size for a continuous block can be set with
1757 config MTRR_SANITIZER_ENABLE_DEFAULT
1758 int "MTRR cleanup enable value (0-1)"
1761 depends on MTRR_SANITIZER
1763 Enable mtrr cleanup default value
1765 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1766 int "MTRR cleanup spare reg num (0-7)"
1769 depends on MTRR_SANITIZER
1771 mtrr cleanup spare entries default, it can be changed via
1772 mtrr_spare_reg_nr=N on the kernel command line.
1776 prompt "x86 PAT support" if EXPERT
1779 Use PAT attributes to setup page level cache control.
1781 PATs are the modern equivalents of MTRRs and are much more
1782 flexible than MTRRs.
1784 Say N here if you see bootup problems (boot crash, boot hang,
1785 spontaneous reboots) or a non-working video driver.
1789 config ARCH_USES_PG_UNCACHED
1795 prompt "User Mode Instruction Prevention" if EXPERT
1797 User Mode Instruction Prevention (UMIP) is a security feature in
1798 some x86 processors. If enabled, a general protection fault is
1799 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1800 executed in user mode. These instructions unnecessarily expose
1801 information about the hardware state.
1803 The vast majority of applications do not use these instructions.
1804 For the very few that do, software emulation is provided in
1805 specific cases in protected and virtual-8086 modes. Emulated
1809 # GCC >= 9 and binutils >= 2.29
1810 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1812 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1813 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1814 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1815 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1821 CET features configured (Shadow stack or IBT)
1823 config X86_KERNEL_IBT
1824 prompt "Indirect Branch Tracking"
1826 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1827 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1828 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1832 Build the kernel with support for Indirect Branch Tracking, a
1833 hardware support course-grain forward-edge Control Flow Integrity
1834 protection. It enforces that all indirect calls must land on
1835 an ENDBR instruction, as such, the compiler will instrument the
1836 code with them to make this happen.
1838 In addition to building the kernel with IBT, seal all functions that
1839 are not indirect call targets, avoiding them ever becoming one.
1841 This requires LTO like objtool runs and will slow down the build. It
1842 does significantly reduce the number of ENDBR instructions in the
1845 config X86_INTEL_MEMORY_PROTECTION_KEYS
1846 prompt "Memory Protection Keys"
1848 # Note: only available in 64-bit mode
1849 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1850 select ARCH_USES_HIGH_VMA_FLAGS
1851 select ARCH_HAS_PKEYS
1853 Memory Protection Keys provides a mechanism for enforcing
1854 page-based protections, but without requiring modification of the
1855 page tables when an application changes protection domains.
1857 For details, see Documentation/core-api/protection-keys.rst
1862 prompt "TSX enable mode"
1863 depends on CPU_SUP_INTEL
1864 default X86_INTEL_TSX_MODE_OFF
1866 Intel's TSX (Transactional Synchronization Extensions) feature
1867 allows to optimize locking protocols through lock elision which
1868 can lead to a noticeable performance boost.
1870 On the other hand it has been shown that TSX can be exploited
1871 to form side channel attacks (e.g. TAA) and chances are there
1872 will be more of those attacks discovered in the future.
1874 Therefore TSX is not enabled by default (aka tsx=off). An admin
1875 might override this decision by tsx=on the command line parameter.
1876 Even with TSX enabled, the kernel will attempt to enable the best
1877 possible TAA mitigation setting depending on the microcode available
1878 for the particular machine.
1880 This option allows to set the default tsx mode between tsx=on, =off
1881 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1884 Say off if not sure, auto if TSX is in use but it should be used on safe
1885 platforms or on if TSX is in use and the security aspect of tsx is not
1888 config X86_INTEL_TSX_MODE_OFF
1891 TSX is disabled if possible - equals to tsx=off command line parameter.
1893 config X86_INTEL_TSX_MODE_ON
1896 TSX is always enabled on TSX capable HW - equals the tsx=on command
1899 config X86_INTEL_TSX_MODE_AUTO
1902 TSX is enabled on TSX capable HW that is believed to be safe against
1903 side channel attacks- equals the tsx=auto command line parameter.
1907 bool "Software Guard eXtensions (SGX)"
1908 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1910 depends on CRYPTO_SHA256=y
1912 select NUMA_KEEP_MEMINFO if NUMA
1915 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1916 that can be used by applications to set aside private regions of code
1917 and data, referred to as enclaves. An enclave's private memory can
1918 only be accessed by code running within the enclave. Accesses from
1919 outside the enclave, including other enclaves, are disallowed by
1924 config X86_USER_SHADOW_STACK
1925 bool "X86 userspace shadow stack"
1928 select ARCH_USES_HIGH_VMA_FLAGS
1931 Shadow stack protection is a hardware feature that detects function
1932 return address corruption. This helps mitigate ROP attacks.
1933 Applications must be enabled to use it, and old userspace does not
1934 get protection "for free".
1936 CPUs supporting shadow stacks were first released in 2020.
1938 See Documentation/arch/x86/shstk.rst for more information.
1943 bool "EFI runtime service support"
1946 select EFI_RUNTIME_WRAPPERS
1947 select ARCH_USE_MEMREMAP_PROT
1948 select EFI_RUNTIME_MAP if KEXEC_CORE
1950 This enables the kernel to use EFI runtime services that are
1951 available (such as the EFI variable services).
1953 This option is only useful on systems that have EFI firmware.
1954 In addition, you should use the latest ELILO loader available
1955 at <http://elilo.sourceforge.net> in order to take advantage
1956 of EFI runtime services. However, even with this option, the
1957 resultant kernel should continue to boot on existing non-EFI
1961 bool "EFI stub support"
1965 This kernel feature allows a bzImage to be loaded directly
1966 by EFI firmware without the use of a bootloader.
1968 See Documentation/admin-guide/efi-stub.rst for more information.
1970 config EFI_HANDOVER_PROTOCOL
1971 bool "EFI handover protocol (DEPRECATED)"
1975 Select this in order to include support for the deprecated EFI
1976 handover protocol, which defines alternative entry points into the
1977 EFI stub. This is a practice that has no basis in the UEFI
1978 specification, and requires a priori knowledge on the part of the
1979 bootloader about Linux/x86 specific ways of passing the command line
1980 and initrd, and where in memory those assets may be loaded.
1982 If in doubt, say Y. Even though the corresponding support is not
1983 present in upstream GRUB or other bootloaders, most distros build
1984 GRUB with numerous downstream patches applied, and may rely on the
1985 handover protocol as as result.
1988 bool "EFI mixed-mode support"
1989 depends on EFI_STUB && X86_64
1991 Enabling this feature allows a 64-bit kernel to be booted
1992 on a 32-bit firmware, provided that your CPU supports 64-bit
1995 Note that it is not possible to boot a mixed-mode enabled
1996 kernel via the EFI boot stub - a bootloader that supports
1997 the EFI handover protocol must be used.
2001 config EFI_FAKE_MEMMAP
2002 bool "Enable EFI fake memory map"
2005 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2006 this parameter, you can add arbitrary attribute to specific memory
2007 range by updating original (firmware provided) EFI memmap. This is
2008 useful for debugging of EFI memmap related feature, e.g., Address
2009 Range Mirroring feature.
2011 config EFI_MAX_FAKE_MEM
2012 int "maximum allowable number of ranges in efi_fake_mem boot option"
2013 depends on EFI_FAKE_MEMMAP
2017 Maximum allowable number of ranges in efi_fake_mem boot option.
2018 Ranges can be set up to this value using comma-separated list.
2019 The default value is 8.
2021 config EFI_RUNTIME_MAP
2022 bool "Export EFI runtime maps to sysfs" if EXPERT
2025 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2026 That memory map is required by the 2nd kernel to set up EFI virtual
2027 mappings after kexec, but can also be used for debugging purposes.
2029 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2031 source "kernel/Kconfig.hz"
2033 config ARCH_SUPPORTS_KEXEC
2036 config ARCH_SUPPORTS_KEXEC_FILE
2037 def_bool X86_64 && CRYPTO && CRYPTO_SHA256
2039 config ARCH_SELECTS_KEXEC_FILE
2041 depends on KEXEC_FILE
2042 select HAVE_IMA_KEXEC if IMA
2044 config ARCH_SUPPORTS_KEXEC_PURGATORY
2047 config ARCH_SUPPORTS_KEXEC_SIG
2050 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2053 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2056 config ARCH_SUPPORTS_KEXEC_JUMP
2059 config ARCH_SUPPORTS_CRASH_DUMP
2060 def_bool X86_64 || (X86_32 && HIGHMEM)
2062 config ARCH_SUPPORTS_CRASH_HOTPLUG
2065 config PHYSICAL_START
2066 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2069 This gives the physical address where the kernel is loaded.
2071 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2072 bzImage will decompress itself to above physical address and
2073 run from there. Otherwise, bzImage will run from the address where
2074 it has been loaded by the boot loader and will ignore above physical
2077 In normal kdump cases one does not have to set/change this option
2078 as now bzImage can be compiled as a completely relocatable image
2079 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2080 address. This option is mainly useful for the folks who don't want
2081 to use a bzImage for capturing the crash dump and want to use a
2082 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2083 to be specifically compiled to run from a specific memory area
2084 (normally a reserved region) and this option comes handy.
2086 So if you are using bzImage for capturing the crash dump,
2087 leave the value here unchanged to 0x1000000 and set
2088 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2089 for capturing the crash dump change this value to start of
2090 the reserved region. In other words, it can be set based on
2091 the "X" value as specified in the "crashkernel=YM@XM"
2092 command line boot parameter passed to the panic-ed
2093 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2094 for more details about crash dumps.
2096 Usage of bzImage for capturing the crash dump is recommended as
2097 one does not have to build two kernels. Same kernel can be used
2098 as production kernel and capture kernel. Above option should have
2099 gone away after relocatable bzImage support is introduced. But it
2100 is present because there are users out there who continue to use
2101 vmlinux for dump capture. This option should go away down the
2104 Don't change this unless you know what you are doing.
2107 bool "Build a relocatable kernel"
2110 This builds a kernel image that retains relocation information
2111 so it can be loaded someplace besides the default 1MB.
2112 The relocations tend to make the kernel binary about 10% larger,
2113 but are discarded at runtime.
2115 One use is for the kexec on panic case where the recovery kernel
2116 must live at a different physical address than the primary
2119 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2120 it has been loaded at and the compile time physical address
2121 (CONFIG_PHYSICAL_START) is used as the minimum location.
2123 config RANDOMIZE_BASE
2124 bool "Randomize the address of the kernel image (KASLR)"
2125 depends on RELOCATABLE
2128 In support of Kernel Address Space Layout Randomization (KASLR),
2129 this randomizes the physical address at which the kernel image
2130 is decompressed and the virtual address where the kernel
2131 image is mapped, as a security feature that deters exploit
2132 attempts relying on knowledge of the location of kernel
2135 On 64-bit, the kernel physical and virtual addresses are
2136 randomized separately. The physical address will be anywhere
2137 between 16MB and the top of physical memory (up to 64TB). The
2138 virtual address will be randomized from 16MB up to 1GB (9 bits
2139 of entropy). Note that this also reduces the memory space
2140 available to kernel modules from 1.5GB to 1GB.
2142 On 32-bit, the kernel physical and virtual addresses are
2143 randomized together. They will be randomized from 16MB up to
2144 512MB (8 bits of entropy).
2146 Entropy is generated using the RDRAND instruction if it is
2147 supported. If RDTSC is supported, its value is mixed into
2148 the entropy pool as well. If neither RDRAND nor RDTSC are
2149 supported, then entropy is read from the i8254 timer. The
2150 usable entropy is limited by the kernel being built using
2151 2GB addressing, and that PHYSICAL_ALIGN must be at a
2152 minimum of 2MB. As a result, only 10 bits of entropy are
2153 theoretically possible, but the implementations are further
2154 limited due to memory layouts.
2158 # Relocation on x86 needs some additional build support
2159 config X86_NEED_RELOCS
2161 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2163 config PHYSICAL_ALIGN
2164 hex "Alignment value to which kernel should be aligned"
2166 range 0x2000 0x1000000 if X86_32
2167 range 0x200000 0x1000000 if X86_64
2169 This value puts the alignment restrictions on physical address
2170 where kernel is loaded and run from. Kernel is compiled for an
2171 address which meets above alignment restriction.
2173 If bootloader loads the kernel at a non-aligned address and
2174 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2175 address aligned to above value and run from there.
2177 If bootloader loads the kernel at a non-aligned address and
2178 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2179 load address and decompress itself to the address it has been
2180 compiled for and run from there. The address for which kernel is
2181 compiled already meets above alignment restrictions. Hence the
2182 end result is that kernel runs from a physical address meeting
2183 above alignment restrictions.
2185 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2186 this value must be a multiple of 0x200000.
2188 Don't change this unless you know what you are doing.
2190 config DYNAMIC_MEMORY_LAYOUT
2193 This option makes base addresses of vmalloc and vmemmap as well as
2194 __PAGE_OFFSET movable during boot.
2196 config RANDOMIZE_MEMORY
2197 bool "Randomize the kernel memory sections"
2199 depends on RANDOMIZE_BASE
2200 select DYNAMIC_MEMORY_LAYOUT
2201 default RANDOMIZE_BASE
2203 Randomizes the base virtual address of kernel memory sections
2204 (physical memory mapping, vmalloc & vmemmap). This security feature
2205 makes exploits relying on predictable memory locations less reliable.
2207 The order of allocations remains unchanged. Entropy is generated in
2208 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2209 configuration have in average 30,000 different possible virtual
2210 addresses for each memory section.
2214 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2215 hex "Physical memory mapping padding" if EXPERT
2216 depends on RANDOMIZE_MEMORY
2217 default "0xa" if MEMORY_HOTPLUG
2219 range 0x1 0x40 if MEMORY_HOTPLUG
2222 Define the padding in terabytes added to the existing physical
2223 memory size during kernel memory randomization. It is useful
2224 for memory hotplug support but reduces the entropy available for
2225 address randomization.
2227 If unsure, leave at the default value.
2229 config ADDRESS_MASKING
2230 bool "Linear Address Masking support"
2233 Linear Address Masking (LAM) modifies the checking that is applied
2234 to 64-bit linear addresses, allowing software to use of the
2235 untranslated address bits for metadata.
2237 The capability can be used for efficient address sanitizers (ASAN)
2238 implementation and for optimizations in JITs.
2246 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2247 depends on COMPAT_32
2249 Certain buggy versions of glibc will crash if they are
2250 presented with a 32-bit vDSO that is not mapped at the address
2251 indicated in its segment table.
2253 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2254 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2255 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2256 the only released version with the bug, but OpenSUSE 9
2257 contains a buggy "glibc 2.3.2".
2259 The symptom of the bug is that everything crashes on startup, saying:
2260 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2262 Saying Y here changes the default value of the vdso32 boot
2263 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2264 This works around the glibc bug but hurts performance.
2266 If unsure, say N: if you are compiling your own kernel, you
2267 are unlikely to be using a buggy version of glibc.
2270 prompt "vsyscall table for legacy applications"
2272 default LEGACY_VSYSCALL_XONLY
2274 Legacy user code that does not know how to find the vDSO expects
2275 to be able to issue three syscalls by calling fixed addresses in
2276 kernel space. Since this location is not randomized with ASLR,
2277 it can be used to assist security vulnerability exploitation.
2279 This setting can be changed at boot time via the kernel command
2280 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2281 is deprecated and can only be enabled using the kernel command
2284 On a system with recent enough glibc (2.14 or newer) and no
2285 static binaries, you can say None without a performance penalty
2286 to improve security.
2288 If unsure, select "Emulate execution only".
2290 config LEGACY_VSYSCALL_XONLY
2291 bool "Emulate execution only"
2293 The kernel traps and emulates calls into the fixed vsyscall
2294 address mapping and does not allow reads. This
2295 configuration is recommended when userspace might use the
2296 legacy vsyscall area but support for legacy binary
2297 instrumentation of legacy code is not needed. It mitigates
2298 certain uses of the vsyscall area as an ASLR-bypassing
2301 config LEGACY_VSYSCALL_NONE
2304 There will be no vsyscall mapping at all. This will
2305 eliminate any risk of ASLR bypass due to the vsyscall
2306 fixed address mapping. Attempts to use the vsyscalls
2307 will be reported to dmesg, so that either old or
2308 malicious userspace programs can be identified.
2313 bool "Built-in kernel command line"
2315 Allow for specifying boot arguments to the kernel at
2316 build time. On some systems (e.g. embedded ones), it is
2317 necessary or convenient to provide some or all of the
2318 kernel boot arguments with the kernel itself (that is,
2319 to not rely on the boot loader to provide them.)
2321 To compile command line arguments into the kernel,
2322 set this option to 'Y', then fill in the
2323 boot arguments in CONFIG_CMDLINE.
2325 Systems with fully functional boot loaders (i.e. non-embedded)
2326 should leave this option set to 'N'.
2329 string "Built-in kernel command string"
2330 depends on CMDLINE_BOOL
2333 Enter arguments here that should be compiled into the kernel
2334 image and used at boot time. If the boot loader provides a
2335 command line at boot time, it is appended to this string to
2336 form the full kernel command line, when the system boots.
2338 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2339 change this behavior.
2341 In most cases, the command line (whether built-in or provided
2342 by the boot loader) should specify the device for the root
2345 config CMDLINE_OVERRIDE
2346 bool "Built-in command line overrides boot loader arguments"
2347 depends on CMDLINE_BOOL && CMDLINE != ""
2349 Set this option to 'Y' to have the kernel ignore the boot loader
2350 command line, and use ONLY the built-in command line.
2352 This is used to work around broken boot loaders. This should
2353 be set to 'N' under normal conditions.
2355 config MODIFY_LDT_SYSCALL
2356 bool "Enable the LDT (local descriptor table)" if EXPERT
2359 Linux can allow user programs to install a per-process x86
2360 Local Descriptor Table (LDT) using the modify_ldt(2) system
2361 call. This is required to run 16-bit or segmented code such as
2362 DOSEMU or some Wine programs. It is also used by some very old
2363 threading libraries.
2365 Enabling this feature adds a small amount of overhead to
2366 context switches and increases the low-level kernel attack
2367 surface. Disabling it removes the modify_ldt(2) system call.
2369 Saying 'N' here may make sense for embedded or server kernels.
2371 config STRICT_SIGALTSTACK_SIZE
2372 bool "Enforce strict size checking for sigaltstack"
2373 depends on DYNAMIC_SIGFRAME
2375 For historical reasons MINSIGSTKSZ is a constant which became
2376 already too small with AVX512 support. Add a mechanism to
2377 enforce strict checking of the sigaltstack size against the
2378 real size of the FPU frame. This option enables the check
2379 by default. It can also be controlled via the kernel command
2380 line option 'strict_sas_size' independent of this config
2381 switch. Enabling it might break existing applications which
2382 allocate a too small sigaltstack but 'work' because they
2383 never get a signal delivered.
2385 Say 'N' unless you want to really enforce this check.
2387 source "kernel/livepatch/Kconfig"
2392 def_bool $(cc-option,-mharden-sls=all)
2394 config CC_HAS_RETURN_THUNK
2395 def_bool $(cc-option,-mfunction-return=thunk-extern)
2397 config CC_HAS_ENTRY_PADDING
2398 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2400 config FUNCTION_PADDING_CFI
2402 default 59 if FUNCTION_ALIGNMENT_64B
2403 default 27 if FUNCTION_ALIGNMENT_32B
2404 default 11 if FUNCTION_ALIGNMENT_16B
2405 default 3 if FUNCTION_ALIGNMENT_8B
2408 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2409 # except Kconfig can't do arithmetic :/
2410 config FUNCTION_PADDING_BYTES
2412 default FUNCTION_PADDING_CFI if CFI_CLANG
2413 default FUNCTION_ALIGNMENT
2417 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2418 select FUNCTION_ALIGNMENT_16B
2422 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2425 config HAVE_CALL_THUNKS
2427 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2433 config PREFIX_SYMBOLS
2435 depends on CALL_PADDING && !CFI_CLANG
2437 menuconfig SPECULATION_MITIGATIONS
2438 bool "Mitigations for speculative execution vulnerabilities"
2441 Say Y here to enable options which enable mitigations for
2442 speculative execution hardware vulnerabilities.
2444 If you say N, all mitigations will be disabled. You really
2445 should know what you are doing to say so.
2447 if SPECULATION_MITIGATIONS
2449 config PAGE_TABLE_ISOLATION
2450 bool "Remove the kernel mapping in user mode"
2452 depends on (X86_64 || X86_PAE)
2454 This feature reduces the number of hardware side channels by
2455 ensuring that the majority of kernel addresses are not mapped
2458 See Documentation/arch/x86/pti.rst for more details.
2461 bool "Avoid speculative indirect branches in kernel"
2462 select OBJTOOL if HAVE_OBJTOOL
2465 Compile kernel with the retpoline compiler options to guard against
2466 kernel-to-user data leaks by avoiding speculative indirect
2467 branches. Requires a compiler with -mindirect-branch=thunk-extern
2468 support for full protection. The kernel may run slower.
2471 bool "Enable return-thunks"
2472 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2473 select OBJTOOL if HAVE_OBJTOOL
2476 Compile the kernel with the return-thunks compiler option to guard
2477 against kernel-to-user data leaks by avoiding return speculation.
2478 Requires a compiler with -mfunction-return=thunk-extern
2479 support for full protection. The kernel may run slower.
2481 config CPU_UNRET_ENTRY
2482 bool "Enable UNRET on kernel entry"
2483 depends on CPU_SUP_AMD && RETHUNK && X86_64
2486 Compile the kernel with support for the retbleed=unret mitigation.
2488 config CALL_DEPTH_TRACKING
2489 bool "Mitigate RSB underflow with call depth tracking"
2490 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2491 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2495 Compile the kernel with call depth tracking to mitigate the Intel
2496 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2497 mitigation is off by default and needs to be enabled on the
2498 kernel command line via the retbleed=stuff option. For
2499 non-affected systems the overhead of this option is marginal as
2500 the call depth tracking is using run-time generated call thunks
2501 in a compiler generated padding area and call patching. This
2502 increases text size by ~5%. For non affected systems this space
2503 is unused. On affected SKL systems this results in a significant
2504 performance gain over the IBRS mitigation.
2506 config CALL_THUNKS_DEBUG
2507 bool "Enable call thunks and call depth tracking debugging"
2508 depends on CALL_DEPTH_TRACKING
2509 select FUNCTION_ALIGNMENT_32B
2512 Enable call/ret counters for imbalance detection and build in
2513 a noisy dmesg about callthunks generation and call patching for
2514 trouble shooting. The debug prints need to be enabled on the
2515 kernel command line with 'debug-callthunks'.
2516 Only enable this when you are debugging call thunks as this
2517 creates a noticeable runtime overhead. If unsure say N.
2519 config CPU_IBPB_ENTRY
2520 bool "Enable IBPB on kernel entry"
2521 depends on CPU_SUP_AMD && X86_64
2524 Compile the kernel with support for the retbleed=ibpb mitigation.
2526 config CPU_IBRS_ENTRY
2527 bool "Enable IBRS on kernel entry"
2528 depends on CPU_SUP_INTEL && X86_64
2531 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2532 This mitigates both spectre_v2 and retbleed at great cost to
2536 bool "Mitigate speculative RAS overflow on AMD"
2537 depends on CPU_SUP_AMD && X86_64 && RETHUNK
2540 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2543 bool "Mitigate Straight-Line-Speculation"
2544 depends on CC_HAS_SLS && X86_64
2545 select OBJTOOL if HAVE_OBJTOOL
2548 Compile the kernel with straight-line-speculation options to guard
2549 against straight line speculation. The kernel image might be slightly
2552 config GDS_FORCE_MITIGATION
2553 bool "Force GDS Mitigation"
2554 depends on CPU_SUP_INTEL
2557 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2558 unprivileged speculative access to data which was previously stored in
2561 This option is equivalent to setting gather_data_sampling=force on the
2562 command line. The microcode mitigation is used if present, otherwise
2563 AVX is disabled as a mitigation. On affected systems that are missing
2564 the microcode any userspace code that unconditionally uses AVX will
2565 break with this option set.
2567 Setting this option on systems not vulnerable to GDS has no effect.
2573 config ARCH_HAS_ADD_PAGES
2575 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2577 menu "Power management and ACPI options"
2579 config ARCH_HIBERNATION_HEADER
2581 depends on HIBERNATION
2583 source "kernel/power/Kconfig"
2585 source "drivers/acpi/Kconfig"
2592 tristate "APM (Advanced Power Management) BIOS support"
2593 depends on X86_32 && PM_SLEEP
2595 APM is a BIOS specification for saving power using several different
2596 techniques. This is mostly useful for battery powered laptops with
2597 APM compliant BIOSes. If you say Y here, the system time will be
2598 reset after a RESUME operation, the /proc/apm device will provide
2599 battery status information, and user-space programs will receive
2600 notification of APM "events" (e.g. battery status change).
2602 If you select "Y" here, you can disable actual use of the APM
2603 BIOS by passing the "apm=off" option to the kernel at boot time.
2605 Note that the APM support is almost completely disabled for
2606 machines with more than one CPU.
2608 In order to use APM, you will need supporting software. For location
2609 and more information, read <file:Documentation/power/apm-acpi.rst>
2610 and the Battery Powered Linux mini-HOWTO, available from
2611 <http://www.tldp.org/docs.html#howto>.
2613 This driver does not spin down disk drives (see the hdparm(8)
2614 manpage ("man 8 hdparm") for that), and it doesn't turn off
2615 VESA-compliant "green" monitors.
2617 This driver does not support the TI 4000M TravelMate and the ACER
2618 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2619 desktop machines also don't have compliant BIOSes, and this driver
2620 may cause those machines to panic during the boot phase.
2622 Generally, if you don't have a battery in your machine, there isn't
2623 much point in using this driver and you should say N. If you get
2624 random kernel OOPSes or reboots that don't seem to be related to
2625 anything, try disabling/enabling this option (or disabling/enabling
2628 Some other things you should try when experiencing seemingly random,
2631 1) make sure that you have enough swap space and that it is
2633 2) pass the "idle=poll" option to the kernel
2634 3) switch on floating point emulation in the kernel and pass
2635 the "no387" option to the kernel
2636 4) pass the "floppy=nodma" option to the kernel
2637 5) pass the "mem=4M" option to the kernel (thereby disabling
2638 all but the first 4 MB of RAM)
2639 6) make sure that the CPU is not over clocked.
2640 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2641 8) disable the cache from your BIOS settings
2642 9) install a fan for the video card or exchange video RAM
2643 10) install a better fan for the CPU
2644 11) exchange RAM chips
2645 12) exchange the motherboard.
2647 To compile this driver as a module, choose M here: the
2648 module will be called apm.
2652 config APM_IGNORE_USER_SUSPEND
2653 bool "Ignore USER SUSPEND"
2655 This option will ignore USER SUSPEND requests. On machines with a
2656 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2657 series notebooks, it is necessary to say Y because of a BIOS bug.
2659 config APM_DO_ENABLE
2660 bool "Enable PM at boot time"
2662 Enable APM features at boot time. From page 36 of the APM BIOS
2663 specification: "When disabled, the APM BIOS does not automatically
2664 power manage devices, enter the Standby State, enter the Suspend
2665 State, or take power saving steps in response to CPU Idle calls."
2666 This driver will make CPU Idle calls when Linux is idle (unless this
2667 feature is turned off -- see "Do CPU IDLE calls", below). This
2668 should always save battery power, but more complicated APM features
2669 will be dependent on your BIOS implementation. You may need to turn
2670 this option off if your computer hangs at boot time when using APM
2671 support, or if it beeps continuously instead of suspending. Turn
2672 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2673 T400CDT. This is off by default since most machines do fine without
2678 bool "Make CPU Idle calls when idle"
2680 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2681 On some machines, this can activate improved power savings, such as
2682 a slowed CPU clock rate, when the machine is idle. These idle calls
2683 are made after the idle loop has run for some length of time (e.g.,
2684 333 mS). On some machines, this will cause a hang at boot time or
2685 whenever the CPU becomes idle. (On machines with more than one CPU,
2686 this option does nothing.)
2688 config APM_DISPLAY_BLANK
2689 bool "Enable console blanking using APM"
2691 Enable console blanking using the APM. Some laptops can use this to
2692 turn off the LCD backlight when the screen blanker of the Linux
2693 virtual console blanks the screen. Note that this is only used by
2694 the virtual console screen blanker, and won't turn off the backlight
2695 when using the X Window system. This also doesn't have anything to
2696 do with your VESA-compliant power-saving monitor. Further, this
2697 option doesn't work for all laptops -- it might not turn off your
2698 backlight at all, or it might print a lot of errors to the console,
2699 especially if you are using gpm.
2701 config APM_ALLOW_INTS
2702 bool "Allow interrupts during APM BIOS calls"
2704 Normally we disable external interrupts while we are making calls to
2705 the APM BIOS as a measure to lessen the effects of a badly behaving
2706 BIOS implementation. The BIOS should reenable interrupts if it
2707 needs to. Unfortunately, some BIOSes do not -- especially those in
2708 many of the newer IBM Thinkpads. If you experience hangs when you
2709 suspend, try setting this to Y. Otherwise, say N.
2713 source "drivers/cpufreq/Kconfig"
2715 source "drivers/cpuidle/Kconfig"
2717 source "drivers/idle/Kconfig"
2721 menu "Bus options (PCI etc.)"
2724 prompt "PCI access mode"
2725 depends on X86_32 && PCI
2728 On PCI systems, the BIOS can be used to detect the PCI devices and
2729 determine their configuration. However, some old PCI motherboards
2730 have BIOS bugs and may crash if this is done. Also, some embedded
2731 PCI-based systems don't have any BIOS at all. Linux can also try to
2732 detect the PCI hardware directly without using the BIOS.
2734 With this option, you can specify how Linux should detect the
2735 PCI devices. If you choose "BIOS", the BIOS will be used,
2736 if you choose "Direct", the BIOS won't be used, and if you
2737 choose "MMConfig", then PCI Express MMCONFIG will be used.
2738 If you choose "Any", the kernel will try MMCONFIG, then the
2739 direct access method and falls back to the BIOS if that doesn't
2740 work. If unsure, go with the default, which is "Any".
2745 config PCI_GOMMCONFIG
2762 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2764 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2767 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2770 bool "Support mmconfig PCI config space access" if X86_64
2772 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2773 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2777 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2781 depends on PCI && XEN
2783 config MMCONF_FAM10H
2785 depends on X86_64 && PCI_MMCONFIG && ACPI
2787 config PCI_CNB20LE_QUIRK
2788 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2791 Read the PCI windows out of the CNB20LE host bridge. This allows
2792 PCI hotplug to work on systems with the CNB20LE chipset which do
2795 There's no public spec for this chipset, and this functionality
2796 is known to be incomplete.
2798 You should say N unless you know you need this.
2801 bool "ISA bus support on modern systems" if EXPERT
2803 Expose ISA bus device drivers and options available for selection and
2804 configuration. Enable this option if your target machine has an ISA
2805 bus. ISA is an older system, displaced by PCI and newer bus
2806 architectures -- if your target machine is modern, it probably does
2807 not have an ISA bus.
2811 # x86_64 have no ISA slots, but can have ISA-style DMA.
2813 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2816 Enables ISA-style DMA support for devices requiring such controllers.
2824 Find out whether you have ISA slots on your motherboard. ISA is the
2825 name of a bus system, i.e. the way the CPU talks to the other stuff
2826 inside your box. Other bus systems are PCI, EISA, MicroChannel
2827 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2828 newer boards don't support it. If you have ISA, say Y, otherwise N.
2831 tristate "NatSemi SCx200 support"
2833 This provides basic support for National Semiconductor's
2834 (now AMD's) Geode processors. The driver probes for the
2835 PCI-IDs of several on-chip devices, so its a good dependency
2836 for other scx200_* drivers.
2838 If compiled as a module, the driver is named scx200.
2840 config SCx200HR_TIMER
2841 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2845 This driver provides a clocksource built upon the on-chip
2846 27MHz high-resolution timer. Its also a workaround for
2847 NSC Geode SC-1100's buggy TSC, which loses time when the
2848 processor goes idle (as is done by the scheduler). The
2849 other workaround is idle=poll boot option.
2852 bool "One Laptop Per Child support"
2860 Add support for detecting the unique features of the OLPC
2864 bool "OLPC XO-1 Power Management"
2865 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2867 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2870 bool "OLPC XO-1 Real Time Clock"
2871 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2873 Add support for the XO-1 real time clock, which can be used as a
2874 programmable wakeup source.
2877 bool "OLPC XO-1 SCI extras"
2878 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2882 Add support for SCI-based features of the OLPC XO-1 laptop:
2883 - EC-driven system wakeups
2887 - AC adapter status updates
2888 - Battery status updates
2890 config OLPC_XO15_SCI
2891 bool "OLPC XO-1.5 SCI extras"
2892 depends on OLPC && ACPI
2895 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2896 - EC-driven system wakeups
2897 - AC adapter status updates
2898 - Battery status updates
2901 bool "PCEngines ALIX System Support (LED setup)"
2904 This option enables system support for the PCEngines ALIX.
2905 At present this just sets up LEDs for GPIO control on
2906 ALIX2/3/6 boards. However, other system specific setup should
2909 Note: You must still enable the drivers for GPIO and LED support
2910 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2912 Note: You have to set alix.force=1 for boards with Award BIOS.
2915 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2918 This option enables system support for the Soekris Engineering net5501.
2921 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2925 This option enables system support for the Traverse Technologies GEOS.
2928 bool "Technologic Systems TS-5500 platform support"
2930 select CHECK_SIGNATURE
2934 This option enables system support for the Technologic Systems TS-5500.
2940 depends on CPU_SUP_AMD && PCI
2944 menu "Binary Emulations"
2946 config IA32_EMULATION
2947 bool "IA32 Emulation"
2949 select ARCH_WANT_OLD_COMPAT_IPC
2951 select COMPAT_OLD_SIGACTION
2953 Include code to run legacy 32-bit programs under a
2954 64-bit kernel. You should likely turn this on, unless you're
2955 100% sure that you don't have any 32-bit programs left.
2958 bool "x32 ABI for 64-bit mode"
2960 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2961 # compressed debug sections to x86_x32 properly:
2962 # https://github.com/ClangBuiltLinux/linux/issues/514
2963 # https://github.com/ClangBuiltLinux/linux/issues/1141
2964 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2966 Include code to run binaries for the x32 native 32-bit ABI
2967 for 64-bit processors. An x32 process gets access to the
2968 full 64-bit register file and wide data path while leaving
2969 pointers at 32 bits for smaller memory footprint.
2973 depends on IA32_EMULATION || X86_32
2975 select OLD_SIGSUSPEND3
2979 depends on IA32_EMULATION || X86_X32_ABI
2981 config COMPAT_FOR_U64_ALIGNMENT
2987 config HAVE_ATOMIC_IOMAP
2991 source "arch/x86/kvm/Kconfig"
2993 source "arch/x86/Kconfig.assembler"