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_SUPPORTS_RT
121 select ARCH_USE_BUILTIN_BSWAP
122 select ARCH_USE_MEMTEST
123 select ARCH_USE_QUEUED_RWLOCKS
124 select ARCH_USE_QUEUED_SPINLOCKS
125 select ARCH_USE_SYM_ANNOTATIONS
126 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
127 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
128 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
129 select ARCH_WANTS_NO_INSTR
130 select ARCH_WANT_GENERAL_HUGETLB
131 select ARCH_WANT_HUGE_PMD_SHARE
132 select ARCH_WANT_LD_ORPHAN_WARN
133 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
134 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
135 select ARCH_WANTS_THP_SWAP if X86_64
136 select ARCH_HAS_PARANOID_L1D_FLUSH
137 select BUILDTIME_TABLE_SORT
139 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
140 select CLOCKSOURCE_WATCHDOG
141 # Word-size accesses may read uninitialized data past the trailing \0
142 # in strings and cause false KMSAN reports.
143 select DCACHE_WORD_ACCESS if !KMSAN
144 select DYNAMIC_SIGFRAME
145 select EDAC_ATOMIC_SCRUB
147 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
148 select GENERIC_CLOCKEVENTS_MIN_ADJUST
149 select GENERIC_CMOS_UPDATE
150 select GENERIC_CPU_AUTOPROBE
151 select GENERIC_CPU_VULNERABILITIES
152 select GENERIC_EARLY_IOREMAP
155 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
156 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
157 select GENERIC_IRQ_MIGRATION if SMP
158 select GENERIC_IRQ_PROBE
159 select GENERIC_IRQ_RESERVATION_MODE
160 select GENERIC_IRQ_SHOW
161 select GENERIC_PENDING_IRQ if SMP
162 select GENERIC_PTDUMP
163 select GENERIC_SMP_IDLE_THREAD
164 select GENERIC_TIME_VSYSCALL
165 select GENERIC_GETTIMEOFDAY
166 select GENERIC_VDSO_TIME_NS
167 select GUP_GET_PXX_LOW_HIGH if X86_PAE
168 select HARDIRQS_SW_RESEND
169 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
171 select HAVE_ACPI_APEI if ACPI
172 select HAVE_ACPI_APEI_NMI if ACPI
173 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
174 select HAVE_ARCH_AUDITSYSCALL
175 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
176 select HAVE_ARCH_HUGE_VMALLOC if X86_64
177 select HAVE_ARCH_JUMP_LABEL
178 select HAVE_ARCH_JUMP_LABEL_RELATIVE
179 select HAVE_ARCH_KASAN if X86_64
180 select HAVE_ARCH_KASAN_VMALLOC if X86_64
181 select HAVE_ARCH_KFENCE
182 select HAVE_ARCH_KMSAN if X86_64
183 select HAVE_ARCH_KGDB
184 select HAVE_ARCH_MMAP_RND_BITS if MMU
185 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
186 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
187 select HAVE_ARCH_PREL32_RELOCATIONS
188 select HAVE_ARCH_SECCOMP_FILTER
189 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
190 select HAVE_ARCH_STACKLEAK
191 select HAVE_ARCH_TRACEHOOK
192 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
193 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
194 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
195 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
196 select HAVE_ARCH_VMAP_STACK if X86_64
197 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
198 select HAVE_ARCH_WITHIN_STACK_FRAMES
199 select HAVE_ASM_MODVERSIONS
200 select HAVE_CMPXCHG_DOUBLE
201 select HAVE_CMPXCHG_LOCAL
202 select HAVE_CONTEXT_TRACKING_USER if X86_64
203 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
204 select HAVE_C_RECORDMCOUNT
205 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
206 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
207 select HAVE_BUILDTIME_MCOUNT_SORT
208 select HAVE_DEBUG_KMEMLEAK
209 select HAVE_DMA_CONTIGUOUS
210 select HAVE_DYNAMIC_FTRACE
211 select HAVE_DYNAMIC_FTRACE_WITH_REGS
212 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
213 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
214 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
215 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
217 select HAVE_EFFICIENT_UNALIGNED_ACCESS
219 select HAVE_EXIT_THREAD
221 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
222 select HAVE_FTRACE_MCOUNT_RECORD
223 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
224 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
225 select HAVE_FUNCTION_TRACER
226 select HAVE_GCC_PLUGINS
227 select HAVE_HW_BREAKPOINT
228 select HAVE_IOREMAP_PROT
229 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
230 select HAVE_IRQ_TIME_ACCOUNTING
231 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
232 select HAVE_KERNEL_BZIP2
233 select HAVE_KERNEL_GZIP
234 select HAVE_KERNEL_LZ4
235 select HAVE_KERNEL_LZMA
236 select HAVE_KERNEL_LZO
237 select HAVE_KERNEL_XZ
238 select HAVE_KERNEL_ZSTD
240 select HAVE_KPROBES_ON_FTRACE
241 select HAVE_FUNCTION_ERROR_INJECTION
242 select HAVE_KRETPROBES
245 select HAVE_LIVEPATCH if X86_64
246 select HAVE_MIXED_BREAKPOINTS_REGS
247 select HAVE_MOD_ARCH_SPECIFIC
250 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
252 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
253 select HAVE_OBJTOOL if X86_64
254 select HAVE_OPTPROBES
255 select HAVE_PCSPKR_PLATFORM
256 select HAVE_PERF_EVENTS
257 select HAVE_PERF_EVENTS_NMI
258 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
260 select HAVE_PERF_REGS
261 select HAVE_PERF_USER_STACK_DUMP
262 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
263 select MMU_GATHER_MERGE_VMAS
264 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
265 select HAVE_REGS_AND_STACK_ACCESS_API
266 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
267 select HAVE_FUNCTION_ARG_ACCESS_API
268 select HAVE_SETUP_PER_CPU_AREA
269 select HAVE_SOFTIRQ_ON_OWN_STACK
270 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
271 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
272 select HAVE_STATIC_CALL
273 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
274 select HAVE_PREEMPT_DYNAMIC_CALL
275 select HAVE_PREEMPT_AUTO
277 select HAVE_RUST if X86_64
278 select HAVE_SYSCALL_TRACEPOINTS
279 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
280 select HAVE_UNSTABLE_SCHED_CLOCK
281 select HAVE_USER_RETURN_NOTIFIER
282 select HAVE_GENERIC_VDSO
283 select HOTPLUG_PARALLEL if SMP && X86_64
284 select HOTPLUG_SMT if SMP
285 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
286 select IRQ_FORCED_THREADING
287 select LOCK_MM_AND_FIND_VMA
288 select NEED_PER_CPU_EMBED_FIRST_CHUNK
289 select NEED_PER_CPU_PAGE_FIRST_CHUNK
290 select NEED_SG_DMA_LENGTH
291 select PCI_DOMAINS if PCI
292 select PCI_LOCKLESS_CONFIG if PCI
295 select RTC_MC146818_LIB
297 select SYSCTL_EXCEPTION_TRACE
298 select THREAD_INFO_IN_TASK
299 select TRACE_IRQFLAGS_SUPPORT
300 select TRACE_IRQFLAGS_NMI_SUPPORT
301 select USER_STACKTRACE_SUPPORT
302 select HAVE_ARCH_KCSAN if X86_64
303 select PROC_PID_ARCH_STATUS if PROC_FS
304 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
305 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
306 select FUNCTION_ALIGNMENT_4B
307 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
308 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
310 config INSTRUCTION_DECODER
312 depends on KPROBES || PERF_EVENTS || UPROBES
316 default "elf32-i386" if X86_32
317 default "elf64-x86-64" if X86_64
319 config LOCKDEP_SUPPORT
322 config STACKTRACE_SUPPORT
328 config ARCH_MMAP_RND_BITS_MIN
332 config ARCH_MMAP_RND_BITS_MAX
336 config ARCH_MMAP_RND_COMPAT_BITS_MIN
339 config ARCH_MMAP_RND_COMPAT_BITS_MAX
345 config GENERIC_ISA_DMA
347 depends on ISA_DMA_API
351 default y if KMSAN || KASAN
356 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
358 config GENERIC_BUG_RELATIVE_POINTERS
361 config ARCH_MAY_HAVE_PC_FDC
363 depends on ISA_DMA_API
365 config GENERIC_CALIBRATE_DELAY
368 config ARCH_HAS_CPU_RELAX
371 config ARCH_HIBERNATION_POSSIBLE
374 config ARCH_SUSPEND_POSSIBLE
380 config KASAN_SHADOW_OFFSET
383 default 0xdffffc0000000000
385 config HAVE_INTEL_TXT
387 depends on INTEL_IOMMU && ACPI
391 depends on X86_32 && SMP
395 depends on X86_64 && SMP
397 config ARCH_SUPPORTS_UPROBES
400 config FIX_EARLYCON_MEM
403 config DYNAMIC_PHYSICAL_MASK
406 config PGTABLE_LEVELS
408 default 5 if X86_5LEVEL
413 config CC_HAS_SANE_STACKPROTECTOR
415 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
416 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
418 We have to make sure stack protector is unconditionally disabled if
419 the compiler produces broken code or if it does not let us control
420 the segment on 32-bit kernels.
422 menu "Processor type and features"
425 bool "Symmetric multi-processing support"
427 This enables support for systems with more than one CPU. If you have
428 a system with only one CPU, say N. If you have a system with more
431 If you say N here, the kernel will run on uni- and multiprocessor
432 machines, but will use only one CPU of a multiprocessor machine. If
433 you say Y here, the kernel will run on many, but not all,
434 uniprocessor machines. On a uniprocessor machine, the kernel
435 will run faster if you say N here.
437 Note that if you say Y here and choose architecture "586" or
438 "Pentium" under "Processor family", the kernel will not work on 486
439 architectures. Similarly, multiprocessor kernels for the "PPro"
440 architecture may not work on all Pentium based boards.
442 People using multiprocessor machines who say Y here should also say
443 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
444 Management" code will be disabled if you say Y here.
446 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
447 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
448 <http://www.tldp.org/docs.html#howto>.
450 If you don't know what to do here, say N.
453 bool "Support x2apic"
454 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
456 This enables x2apic support on CPUs that have this feature.
458 This allows 32-bit apic IDs (so it can support very large systems),
459 and accesses the local apic via MSRs not via mmio.
461 Some Intel systems circa 2022 and later are locked into x2APIC mode
462 and can not fall back to the legacy APIC modes if SGX or TDX are
463 enabled in the BIOS. They will boot with very reduced functionality
464 without enabling this option.
466 If you don't know what to do here, say N.
469 bool "Enable MPS table" if ACPI
471 depends on X86_LOCAL_APIC
473 For old smp systems that do not have proper acpi support. Newer systems
474 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
478 depends on X86_GOLDFISH
480 config X86_CPU_RESCTRL
481 bool "x86 CPU resource control support"
482 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
484 select PROC_CPU_RESCTRL if PROC_FS
486 Enable x86 CPU resource control support.
488 Provide support for the allocation and monitoring of system resources
491 Intel calls this Intel Resource Director Technology
492 (Intel(R) RDT). More information about RDT can be found in the
493 Intel x86 Architecture Software Developer Manual.
495 AMD calls this AMD Platform Quality of Service (AMD QoS).
496 More information about AMD QoS can be found in the AMD64 Technology
497 Platform Quality of Service Extensions manual.
503 bool "Support for big SMP systems with more than 8 CPUs"
506 This option is needed for the systems that have more than 8 CPUs.
508 config X86_EXTENDED_PLATFORM
509 bool "Support for extended (non-PC) x86 platforms"
512 If you disable this option then the kernel will only support
513 standard PC platforms. (which covers the vast majority of
516 If you enable this option then you'll be able to select support
517 for the following (non-PC) 32 bit x86 platforms:
518 Goldfish (Android emulator)
521 SGI 320/540 (Visual Workstation)
522 STA2X11-based (e.g. Northville)
523 Moorestown MID devices
525 If you have one of these systems, or if you want to build a
526 generic distribution kernel, say Y here - otherwise say N.
530 config X86_EXTENDED_PLATFORM
531 bool "Support for extended (non-PC) x86 platforms"
534 If you disable this option then the kernel will only support
535 standard PC platforms. (which covers the vast majority of
538 If you enable this option then you'll be able to select support
539 for the following (non-PC) 64 bit x86 platforms:
544 If you have one of these systems, or if you want to build a
545 generic distribution kernel, say Y here - otherwise say N.
547 # This is an alphabetically sorted list of 64 bit extended platforms
548 # Please maintain the alphabetic order if and when there are additions
550 bool "Numascale NumaChip"
552 depends on X86_EXTENDED_PLATFORM
555 depends on X86_X2APIC
556 depends on PCI_MMCONFIG
558 Adds support for Numascale NumaChip large-SMP systems. Needed to
559 enable more than ~168 cores.
560 If you don't have one of these, you should say N here.
564 select HYPERVISOR_GUEST
566 depends on X86_64 && PCI
567 depends on X86_EXTENDED_PLATFORM
570 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
571 supposed to run on these EM64T-based machines. Only choose this option
572 if you have one of these machines.
575 bool "SGI Ultraviolet"
577 depends on X86_EXTENDED_PLATFORM
580 depends on KEXEC_CORE
581 depends on X86_X2APIC
584 This option is needed in order to support SGI Ultraviolet systems.
585 If you don't have one of these, you should say N here.
587 # Following is an alphabetically sorted list of 32 bit extended platforms
588 # Please maintain the alphabetic order if and when there are additions
591 bool "Goldfish (Virtual Platform)"
592 depends on X86_EXTENDED_PLATFORM
594 Enable support for the Goldfish virtual platform used primarily
595 for Android development. Unless you are building for the Android
596 Goldfish emulator say N here.
599 bool "CE4100 TV platform"
601 depends on PCI_GODIRECT
602 depends on X86_IO_APIC
604 depends on X86_EXTENDED_PLATFORM
605 select X86_REBOOTFIXUPS
607 select OF_EARLY_FLATTREE
609 Select for the Intel CE media processor (CE4100) SOC.
610 This option compiles in support for the CE4100 SOC for settop
611 boxes and media devices.
614 bool "Intel MID platform support"
615 depends on X86_EXTENDED_PLATFORM
616 depends on X86_PLATFORM_DEVICES
618 depends on X86_64 || (PCI_GOANY && X86_32)
619 depends on X86_IO_APIC
624 Select to build a kernel capable of supporting Intel MID (Mobile
625 Internet Device) platform systems which do not have the PCI legacy
626 interfaces. If you are building for a PC class system say N here.
628 Intel MID platforms are based on an Intel processor and chipset which
629 consume less power than most of the x86 derivatives.
631 config X86_INTEL_QUARK
632 bool "Intel Quark platform support"
634 depends on X86_EXTENDED_PLATFORM
635 depends on X86_PLATFORM_DEVICES
639 depends on X86_IO_APIC
644 Select to include support for Quark X1000 SoC.
645 Say Y here if you have a Quark based system such as the Arduino
646 compatible Intel Galileo.
648 config X86_INTEL_LPSS
649 bool "Intel Low Power Subsystem Support"
650 depends on X86 && ACPI && PCI
655 Select to build support for Intel Low Power Subsystem such as
656 found on Intel Lynxpoint PCH. Selecting this option enables
657 things like clock tree (common clock framework) and pincontrol
658 which are needed by the LPSS peripheral drivers.
660 config X86_AMD_PLATFORM_DEVICE
661 bool "AMD ACPI2Platform devices support"
666 Select to interpret AMD specific ACPI device to platform device
667 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
668 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
669 implemented under PINCTRL subsystem.
672 tristate "Intel SoC IOSF Sideband support for SoC platforms"
675 This option enables sideband register access support for Intel SoC
676 platforms. On these platforms the IOSF sideband is used in lieu of
677 MSR's for some register accesses, mostly but not limited to thermal
678 and power. Drivers may query the availability of this device to
679 determine if they need the sideband in order to work on these
680 platforms. The sideband is available on the following SoC products.
681 This list is not meant to be exclusive.
686 You should say Y if you are running a kernel on one of these SoC's.
688 config IOSF_MBI_DEBUG
689 bool "Enable IOSF sideband access through debugfs"
690 depends on IOSF_MBI && DEBUG_FS
692 Select this option to expose the IOSF sideband access registers (MCR,
693 MDR, MCRX) through debugfs to write and read register information from
694 different units on the SoC. This is most useful for obtaining device
695 state information for debug and analysis. As this is a general access
696 mechanism, users of this option would have specific knowledge of the
697 device they want to access.
699 If you don't require the option or are in doubt, say N.
702 bool "RDC R-321x SoC"
704 depends on X86_EXTENDED_PLATFORM
706 select X86_REBOOTFIXUPS
708 This option is needed for RDC R-321x system-on-chip, also known
710 If you don't have one of these chips, you should say N here.
712 config X86_32_NON_STANDARD
713 bool "Support non-standard 32-bit SMP architectures"
714 depends on X86_32 && SMP
715 depends on X86_EXTENDED_PLATFORM
717 This option compiles in the bigsmp and STA2X11 default
718 subarchitectures. It is intended for a generic binary
719 kernel. If you select them all, kernel will probe it one by
720 one and will fallback to default.
722 # Alphabetically sorted list of Non standard 32 bit platforms
724 config X86_SUPPORTS_MEMORY_FAILURE
726 # MCE code calls memory_failure():
728 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
729 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
730 depends on X86_64 || !SPARSEMEM
731 select ARCH_SUPPORTS_MEMORY_FAILURE
734 bool "STA2X11 Companion Chip Support"
735 depends on X86_32_NON_STANDARD && PCI
740 This adds support for boards based on the STA2X11 IO-Hub,
741 a.k.a. "ConneXt". The chip is used in place of the standard
742 PC chipset, so all "standard" peripherals are missing. If this
743 option is selected the kernel will still be able to boot on
744 standard PC machines.
747 tristate "Eurobraille/Iris poweroff module"
750 The Iris machines from EuroBraille do not have APM or ACPI support
751 to shut themselves down properly. A special I/O sequence is
752 needed to do so, which is what this module does at
755 This is only for Iris machines from EuroBraille.
759 config SCHED_OMIT_FRAME_POINTER
761 prompt "Single-depth WCHAN output"
764 Calculate simpler /proc/<PID>/wchan values. If this option
765 is disabled then wchan values will recurse back to the
766 caller function. This provides more accurate wchan values,
767 at the expense of slightly more scheduling overhead.
769 If in doubt, say "Y".
771 menuconfig HYPERVISOR_GUEST
772 bool "Linux guest support"
774 Say Y here to enable options for running Linux under various hyper-
775 visors. This option enables basic hypervisor detection and platform
778 If you say N, all options in this submenu will be skipped and
779 disabled, and Linux guest support won't be built in.
784 bool "Enable paravirtualization code"
785 depends on HAVE_STATIC_CALL
787 This changes the kernel so it can modify itself when it is run
788 under a hypervisor, potentially improving performance significantly
789 over full virtualization. However, when run without a hypervisor
790 the kernel is theoretically slower and slightly larger.
795 config PARAVIRT_DEBUG
796 bool "paravirt-ops debugging"
797 depends on PARAVIRT && DEBUG_KERNEL
799 Enable to debug paravirt_ops internals. Specifically, BUG if
800 a paravirt_op is missing when it is called.
802 config PARAVIRT_SPINLOCKS
803 bool "Paravirtualization layer for spinlocks"
804 depends on PARAVIRT && SMP
806 Paravirtualized spinlocks allow a pvops backend to replace the
807 spinlock implementation with something virtualization-friendly
808 (for example, block the virtual CPU rather than spinning).
810 It has a minimal impact on native kernels and gives a nice performance
811 benefit on paravirtualized KVM / Xen kernels.
813 If you are unsure how to answer this question, answer Y.
815 config X86_HV_CALLBACK_VECTOR
818 source "arch/x86/xen/Kconfig"
821 bool "KVM Guest support (including kvmclock)"
823 select PARAVIRT_CLOCK
824 select ARCH_CPUIDLE_HALTPOLL
825 select X86_HV_CALLBACK_VECTOR
828 This option enables various optimizations for running under the KVM
829 hypervisor. It includes a paravirtualized clock, so that instead
830 of relying on a PIT (or probably other) emulation by the
831 underlying device model, the host provides the guest with
832 timing infrastructure such as time of day, and system time
834 config ARCH_CPUIDLE_HALTPOLL
836 prompt "Disable host haltpoll when loading haltpoll driver"
838 If virtualized under KVM, disable host haltpoll.
841 bool "Support for running PVH guests"
843 This option enables the PVH entry point for guest virtual machines
844 as specified in the x86/HVM direct boot ABI.
846 config PARAVIRT_TIME_ACCOUNTING
847 bool "Paravirtual steal time accounting"
850 Select this option to enable fine granularity task steal time
851 accounting. Time spent executing other tasks in parallel with
852 the current vCPU is discounted from the vCPU power. To account for
853 that, there can be a small performance impact.
855 If in doubt, say N here.
857 config PARAVIRT_CLOCK
860 config JAILHOUSE_GUEST
861 bool "Jailhouse non-root cell support"
862 depends on X86_64 && PCI
865 This option allows to run Linux as guest in a Jailhouse non-root
866 cell. You can leave this option disabled if you only want to start
867 Jailhouse and run Linux afterwards in the root cell.
870 bool "ACRN Guest support"
872 select X86_HV_CALLBACK_VECTOR
874 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
875 a flexible, lightweight reference open-source hypervisor, built with
876 real-time and safety-criticality in mind. It is built for embedded
877 IOT with small footprint and real-time features. More details can be
878 found in https://projectacrn.org/.
880 config INTEL_TDX_GUEST
881 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
882 depends on X86_64 && CPU_SUP_INTEL
883 depends on X86_X2APIC
885 select ARCH_HAS_CC_PLATFORM
886 select X86_MEM_ENCRYPT
888 select UNACCEPTED_MEMORY
890 Support running as a guest under Intel TDX. Without this support,
891 the guest kernel can not boot or run under TDX.
892 TDX includes memory encryption and integrity capabilities
893 which protect the confidentiality and integrity of guest
894 memory contents and CPU state. TDX guests are protected from
895 some attacks from the VMM.
897 endif # HYPERVISOR_GUEST
899 source "arch/x86/Kconfig.cpu"
903 prompt "HPET Timer Support" if X86_32
905 Use the IA-PC HPET (High Precision Event Timer) to manage
906 time in preference to the PIT and RTC, if a HPET is
908 HPET is the next generation timer replacing legacy 8254s.
909 The HPET provides a stable time base on SMP
910 systems, unlike the TSC, but it is more expensive to access,
911 as it is off-chip. The interface used is documented
912 in the HPET spec, revision 1.
914 You can safely choose Y here. However, HPET will only be
915 activated if the platform and the BIOS support this feature.
916 Otherwise the 8254 will be used for timing services.
918 Choose N to continue using the legacy 8254 timer.
920 config HPET_EMULATE_RTC
922 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
924 # Mark as expert because too many people got it wrong.
925 # The code disables itself when not needed.
928 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
929 bool "Enable DMI scanning" if EXPERT
931 Enabled scanning of DMI to identify machine quirks. Say Y
932 here unless you have verified that your setup is not
933 affected by entries in the DMI blacklist. Required by PNP
937 bool "Old AMD GART IOMMU support"
941 depends on X86_64 && PCI && AMD_NB
943 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
944 GART based hardware IOMMUs.
946 The GART supports full DMA access for devices with 32-bit access
947 limitations, on systems with more than 3 GB. This is usually needed
948 for USB, sound, many IDE/SATA chipsets and some other devices.
950 Newer systems typically have a modern AMD IOMMU, supported via
951 the CONFIG_AMD_IOMMU=y config option.
953 In normal configurations this driver is only active when needed:
954 there's more than 3 GB of memory and the system contains a
955 32-bit limited device.
959 config BOOT_VESA_SUPPORT
962 If true, at least one selected framebuffer driver can take advantage
963 of VESA video modes set at an early boot stage via the vga= parameter.
966 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
967 depends on X86_64 && SMP && DEBUG_KERNEL
968 select CPUMASK_OFFSTACK
970 Enable maximum number of CPUS and NUMA Nodes for this architecture.
974 # The maximum number of CPUs supported:
976 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
977 # and which can be configured interactively in the
978 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
980 # The ranges are different on 32-bit and 64-bit kernels, depending on
981 # hardware capabilities and scalability features of the kernel.
983 # ( If MAXSMP is enabled we just use the highest possible value and disable
984 # interactive configuration. )
987 config NR_CPUS_RANGE_BEGIN
989 default NR_CPUS_RANGE_END if MAXSMP
993 config NR_CPUS_RANGE_END
996 default 64 if SMP && X86_BIGSMP
997 default 8 if SMP && !X86_BIGSMP
1000 config NR_CPUS_RANGE_END
1003 default 8192 if SMP && CPUMASK_OFFSTACK
1004 default 512 if SMP && !CPUMASK_OFFSTACK
1007 config NR_CPUS_DEFAULT
1010 default 32 if X86_BIGSMP
1014 config NR_CPUS_DEFAULT
1017 default 8192 if MAXSMP
1022 int "Maximum number of CPUs" if SMP && !MAXSMP
1023 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1024 default NR_CPUS_DEFAULT
1026 This allows you to specify the maximum number of CPUs which this
1027 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1028 supported value is 8192, otherwise the maximum value is 512. The
1029 minimum value which makes sense is 2.
1031 This is purely to save memory: each supported CPU adds about 8KB
1032 to the kernel image.
1034 config SCHED_CLUSTER
1035 bool "Cluster scheduler support"
1039 Cluster scheduler support improves the CPU scheduler's decision
1040 making when dealing with machines that have clusters of CPUs.
1041 Cluster usually means a couple of CPUs which are placed closely
1042 by sharing mid-level caches, last-level cache tags or internal
1050 prompt "Multi-core scheduler support"
1053 Multi-core scheduler support improves the CPU scheduler's decision
1054 making when dealing with multi-core CPU chips at a cost of slightly
1055 increased overhead in some places. If unsure say N here.
1057 config SCHED_MC_PRIO
1058 bool "CPU core priorities scheduler support"
1059 depends on SCHED_MC && CPU_SUP_INTEL
1060 select X86_INTEL_PSTATE
1064 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1065 core ordering determined at manufacturing time, which allows
1066 certain cores to reach higher turbo frequencies (when running
1067 single threaded workloads) than others.
1069 Enabling this kernel feature teaches the scheduler about
1070 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1071 scheduler's CPU selection logic accordingly, so that higher
1072 overall system performance can be achieved.
1074 This feature will have no effect on CPUs without this feature.
1076 If unsure say Y here.
1080 depends on !SMP && X86_LOCAL_APIC
1083 bool "Local APIC support on uniprocessors" if !PCI_MSI
1085 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1087 A local APIC (Advanced Programmable Interrupt Controller) is an
1088 integrated interrupt controller in the CPU. If you have a single-CPU
1089 system which has a processor with a local APIC, you can say Y here to
1090 enable and use it. If you say Y here even though your machine doesn't
1091 have a local APIC, then the kernel will still run with no slowdown at
1092 all. The local APIC supports CPU-generated self-interrupts (timer,
1093 performance counters), and the NMI watchdog which detects hard
1096 config X86_UP_IOAPIC
1097 bool "IO-APIC support on uniprocessors"
1098 depends on X86_UP_APIC
1100 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1101 SMP-capable replacement for PC-style interrupt controllers. Most
1102 SMP systems and many recent uniprocessor systems have one.
1104 If you have a single-CPU system with an IO-APIC, you can say Y here
1105 to use it. If you say Y here even though your machine doesn't have
1106 an IO-APIC, then the kernel will still run with no slowdown at all.
1108 config X86_LOCAL_APIC
1110 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1111 select IRQ_DOMAIN_HIERARCHY
1115 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1117 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1118 bool "Reroute for broken boot IRQs"
1119 depends on X86_IO_APIC
1121 This option enables a workaround that fixes a source of
1122 spurious interrupts. This is recommended when threaded
1123 interrupt handling is used on systems where the generation of
1124 superfluous "boot interrupts" cannot be disabled.
1126 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1127 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1128 kernel does during interrupt handling). On chipsets where this
1129 boot IRQ generation cannot be disabled, this workaround keeps
1130 the original IRQ line masked so that only the equivalent "boot
1131 IRQ" is delivered to the CPUs. The workaround also tells the
1132 kernel to set up the IRQ handler on the boot IRQ line. In this
1133 way only one interrupt is delivered to the kernel. Otherwise
1134 the spurious second interrupt may cause the kernel to bring
1135 down (vital) interrupt lines.
1137 Only affects "broken" chipsets. Interrupt sharing may be
1138 increased on these systems.
1141 bool "Machine Check / overheating reporting"
1142 select GENERIC_ALLOCATOR
1145 Machine Check support allows the processor to notify the
1146 kernel if it detects a problem (e.g. overheating, data corruption).
1147 The action the kernel takes depends on the severity of the problem,
1148 ranging from warning messages to halting the machine.
1150 config X86_MCELOG_LEGACY
1151 bool "Support for deprecated /dev/mcelog character device"
1154 Enable support for /dev/mcelog which is needed by the old mcelog
1155 userspace logging daemon. Consider switching to the new generation
1158 config X86_MCE_INTEL
1160 prompt "Intel MCE features"
1161 depends on X86_MCE && X86_LOCAL_APIC
1163 Additional support for intel specific MCE features such as
1164 the thermal monitor.
1168 prompt "AMD MCE features"
1169 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1171 Additional support for AMD specific MCE features such as
1172 the DRAM Error Threshold.
1174 config X86_ANCIENT_MCE
1175 bool "Support for old Pentium 5 / WinChip machine checks"
1176 depends on X86_32 && X86_MCE
1178 Include support for machine check handling on old Pentium 5 or WinChip
1179 systems. These typically need to be enabled explicitly on the command
1182 config X86_MCE_THRESHOLD
1183 depends on X86_MCE_AMD || X86_MCE_INTEL
1186 config X86_MCE_INJECT
1187 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1188 tristate "Machine check injector support"
1190 Provide support for injecting machine checks for testing purposes.
1191 If you don't know what a machine check is and you don't do kernel
1192 QA it is safe to say n.
1194 source "arch/x86/events/Kconfig"
1196 config X86_LEGACY_VM86
1197 bool "Legacy VM86 support"
1200 This option allows user programs to put the CPU into V8086
1201 mode, which is an 80286-era approximation of 16-bit real mode.
1203 Some very old versions of X and/or vbetool require this option
1204 for user mode setting. Similarly, DOSEMU will use it if
1205 available to accelerate real mode DOS programs. However, any
1206 recent version of DOSEMU, X, or vbetool should be fully
1207 functional even without kernel VM86 support, as they will all
1208 fall back to software emulation. Nevertheless, if you are using
1209 a 16-bit DOS program where 16-bit performance matters, vm86
1210 mode might be faster than emulation and you might want to
1213 Note that any app that works on a 64-bit kernel is unlikely to
1214 need this option, as 64-bit kernels don't, and can't, support
1215 V8086 mode. This option is also unrelated to 16-bit protected
1216 mode and is not needed to run most 16-bit programs under Wine.
1218 Enabling this option increases the complexity of the kernel
1219 and slows down exception handling a tiny bit.
1221 If unsure, say N here.
1225 default X86_LEGACY_VM86
1228 bool "Enable support for 16-bit segments" if EXPERT
1230 depends on MODIFY_LDT_SYSCALL
1232 This option is required by programs like Wine to run 16-bit
1233 protected mode legacy code on x86 processors. Disabling
1234 this option saves about 300 bytes on i386, or around 6K text
1235 plus 16K runtime memory on x86-64,
1239 depends on X86_16BIT && X86_32
1243 depends on X86_16BIT && X86_64
1245 config X86_VSYSCALL_EMULATION
1246 bool "Enable vsyscall emulation" if EXPERT
1250 This enables emulation of the legacy vsyscall page. Disabling
1251 it is roughly equivalent to booting with vsyscall=none, except
1252 that it will also disable the helpful warning if a program
1253 tries to use a vsyscall. With this option set to N, offending
1254 programs will just segfault, citing addresses of the form
1257 This option is required by many programs built before 2013, and
1258 care should be used even with newer programs if set to N.
1260 Disabling this option saves about 7K of kernel size and
1261 possibly 4K of additional runtime pagetable memory.
1263 config X86_IOPL_IOPERM
1264 bool "IOPERM and IOPL Emulation"
1267 This enables the ioperm() and iopl() syscalls which are necessary
1268 for legacy applications.
1270 Legacy IOPL support is an overbroad mechanism which allows user
1271 space aside of accessing all 65536 I/O ports also to disable
1272 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1273 capabilities and permission from potentially active security
1276 The emulation restricts the functionality of the syscall to
1277 only allowing the full range I/O port access, but prevents the
1278 ability to disable interrupts from user space which would be
1279 granted if the hardware IOPL mechanism would be used.
1282 tristate "Toshiba Laptop support"
1285 This adds a driver to safely access the System Management Mode of
1286 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1287 not work on models with a Phoenix BIOS. The System Management Mode
1288 is used to set the BIOS and power saving options on Toshiba portables.
1290 For information on utilities to make use of this driver see the
1291 Toshiba Linux utilities web site at:
1292 <http://www.buzzard.org.uk/toshiba/>.
1294 Say Y if you intend to run this kernel on a Toshiba portable.
1297 config X86_REBOOTFIXUPS
1298 bool "Enable X86 board specific fixups for reboot"
1301 This enables chipset and/or board specific fixups to be done
1302 in order to get reboot to work correctly. This is only needed on
1303 some combinations of hardware and BIOS. The symptom, for which
1304 this config is intended, is when reboot ends with a stalled/hung
1307 Currently, the only fixup is for the Geode machines using
1308 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1310 Say Y if you want to enable the fixup. Currently, it's safe to
1311 enable this option even if you don't need it.
1316 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1318 config MICROCODE_LATE_LOADING
1319 bool "Late microcode loading (DANGEROUS)"
1321 depends on MICROCODE
1323 Loading microcode late, when the system is up and executing instructions
1324 is a tricky business and should be avoided if possible. Just the sequence
1325 of synchronizing all cores and SMT threads is one fragile dance which does
1326 not guarantee that cores might not softlock after the loading. Therefore,
1327 use this at your own risk. Late loading taints the kernel too.
1330 tristate "/dev/cpu/*/msr - Model-specific register support"
1332 This device gives privileged processes access to the x86
1333 Model-Specific Registers (MSRs). It is a character device with
1334 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1335 MSR accesses are directed to a specific CPU on multi-processor
1339 tristate "/dev/cpu/*/cpuid - CPU information support"
1341 This device gives processes access to the x86 CPUID instruction to
1342 be executed on a specific processor. It is a character device
1343 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1347 prompt "High Memory Support"
1354 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1355 However, the address space of 32-bit x86 processors is only 4
1356 Gigabytes large. That means that, if you have a large amount of
1357 physical memory, not all of it can be "permanently mapped" by the
1358 kernel. The physical memory that's not permanently mapped is called
1361 If you are compiling a kernel which will never run on a machine with
1362 more than 1 Gigabyte total physical RAM, answer "off" here (default
1363 choice and suitable for most users). This will result in a "3GB/1GB"
1364 split: 3GB are mapped so that each process sees a 3GB virtual memory
1365 space and the remaining part of the 4GB virtual memory space is used
1366 by the kernel to permanently map as much physical memory as
1369 If the machine has between 1 and 4 Gigabytes physical RAM, then
1372 If more than 4 Gigabytes is used then answer "64GB" here. This
1373 selection turns Intel PAE (Physical Address Extension) mode on.
1374 PAE implements 3-level paging on IA32 processors. PAE is fully
1375 supported by Linux, PAE mode is implemented on all recent Intel
1376 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1377 then the kernel will not boot on CPUs that don't support PAE!
1379 The actual amount of total physical memory will either be
1380 auto detected or can be forced by using a kernel command line option
1381 such as "mem=256M". (Try "man bootparam" or see the documentation of
1382 your boot loader (lilo or loadlin) about how to pass options to the
1383 kernel at boot time.)
1385 If unsure, say "off".
1390 Select this if you have a 32-bit processor and between 1 and 4
1391 gigabytes of physical RAM.
1395 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1398 Select this if you have a 32-bit processor and more than 4
1399 gigabytes of physical RAM.
1404 prompt "Memory split" if EXPERT
1408 Select the desired split between kernel and user memory.
1410 If the address range available to the kernel is less than the
1411 physical memory installed, the remaining memory will be available
1412 as "high memory". Accessing high memory is a little more costly
1413 than low memory, as it needs to be mapped into the kernel first.
1414 Note that increasing the kernel address space limits the range
1415 available to user programs, making the address space there
1416 tighter. Selecting anything other than the default 3G/1G split
1417 will also likely make your kernel incompatible with binary-only
1420 If you are not absolutely sure what you are doing, leave this
1424 bool "3G/1G user/kernel split"
1425 config VMSPLIT_3G_OPT
1427 bool "3G/1G user/kernel split (for full 1G low memory)"
1429 bool "2G/2G user/kernel split"
1430 config VMSPLIT_2G_OPT
1432 bool "2G/2G user/kernel split (for full 2G low memory)"
1434 bool "1G/3G user/kernel split"
1439 default 0xB0000000 if VMSPLIT_3G_OPT
1440 default 0x80000000 if VMSPLIT_2G
1441 default 0x78000000 if VMSPLIT_2G_OPT
1442 default 0x40000000 if VMSPLIT_1G
1448 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1451 bool "PAE (Physical Address Extension) Support"
1452 depends on X86_32 && !HIGHMEM4G
1453 select PHYS_ADDR_T_64BIT
1456 PAE is required for NX support, and furthermore enables
1457 larger swapspace support for non-overcommit purposes. It
1458 has the cost of more pagetable lookup overhead, and also
1459 consumes more pagetable space per process.
1462 bool "Enable 5-level page tables support"
1464 select DYNAMIC_MEMORY_LAYOUT
1465 select SPARSEMEM_VMEMMAP
1468 5-level paging enables access to larger address space:
1469 up to 128 PiB of virtual address space and 4 PiB of
1470 physical address space.
1472 It will be supported by future Intel CPUs.
1474 A kernel with the option enabled can be booted on machines that
1475 support 4- or 5-level paging.
1477 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1482 config X86_DIRECT_GBPAGES
1486 Certain kernel features effectively disable kernel
1487 linear 1 GB mappings (even if the CPU otherwise
1488 supports them), so don't confuse the user by printing
1489 that we have them enabled.
1491 config X86_CPA_STATISTICS
1492 bool "Enable statistic for Change Page Attribute"
1495 Expose statistics about the Change Page Attribute mechanism, which
1496 helps to determine the effectiveness of preserving large and huge
1497 page mappings when mapping protections are changed.
1499 config X86_MEM_ENCRYPT
1500 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1501 select DYNAMIC_PHYSICAL_MASK
1504 config AMD_MEM_ENCRYPT
1505 bool "AMD Secure Memory Encryption (SME) support"
1506 depends on X86_64 && CPU_SUP_AMD
1508 select DMA_COHERENT_POOL
1509 select ARCH_USE_MEMREMAP_PROT
1510 select INSTRUCTION_DECODER
1511 select ARCH_HAS_CC_PLATFORM
1512 select X86_MEM_ENCRYPT
1513 select UNACCEPTED_MEMORY
1515 Say yes to enable support for the encryption of system memory.
1516 This requires an AMD processor that supports Secure Memory
1519 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1520 bool "Activate AMD Secure Memory Encryption (SME) by default"
1521 depends on AMD_MEM_ENCRYPT
1523 Say yes to have system memory encrypted by default if running on
1524 an AMD processor that supports Secure Memory Encryption (SME).
1526 If set to Y, then the encryption of system memory can be
1527 deactivated with the mem_encrypt=off command line option.
1529 If set to N, then the encryption of system memory can be
1530 activated with the mem_encrypt=on command line option.
1532 # Common NUMA Features
1534 bool "NUMA Memory Allocation and Scheduler Support"
1536 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1537 default y if X86_BIGSMP
1538 select USE_PERCPU_NUMA_NODE_ID
1540 Enable NUMA (Non-Uniform Memory Access) support.
1542 The kernel will try to allocate memory used by a CPU on the
1543 local memory controller of the CPU and add some more
1544 NUMA awareness to the kernel.
1546 For 64-bit this is recommended if the system is Intel Core i7
1547 (or later), AMD Opteron, or EM64T NUMA.
1549 For 32-bit this is only needed if you boot a 32-bit
1550 kernel on a 64-bit NUMA platform.
1552 Otherwise, you should say N.
1556 prompt "Old style AMD Opteron NUMA detection"
1557 depends on X86_64 && NUMA && PCI
1559 Enable AMD NUMA node topology detection. You should say Y here if
1560 you have a multi processor AMD system. This uses an old method to
1561 read the NUMA configuration directly from the builtin Northbridge
1562 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1563 which also takes priority if both are compiled in.
1565 config X86_64_ACPI_NUMA
1567 prompt "ACPI NUMA detection"
1568 depends on X86_64 && NUMA && ACPI && PCI
1571 Enable ACPI SRAT based node topology detection.
1574 bool "NUMA emulation"
1577 Enable NUMA emulation. A flat machine will be split
1578 into virtual nodes when booted with "numa=fake=N", where N is the
1579 number of nodes. This is only useful for debugging.
1582 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1584 default "10" if MAXSMP
1585 default "6" if X86_64
1589 Specify the maximum number of NUMA Nodes available on the target
1590 system. Increases memory reserved to accommodate various tables.
1592 config ARCH_FLATMEM_ENABLE
1594 depends on X86_32 && !NUMA
1596 config ARCH_SPARSEMEM_ENABLE
1598 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1599 select SPARSEMEM_STATIC if X86_32
1600 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1602 config ARCH_SPARSEMEM_DEFAULT
1603 def_bool X86_64 || (NUMA && X86_32)
1605 config ARCH_SELECT_MEMORY_MODEL
1607 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1609 config ARCH_MEMORY_PROBE
1610 bool "Enable sysfs memory/probe interface"
1611 depends on MEMORY_HOTPLUG
1613 This option enables a sysfs memory/probe interface for testing.
1614 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1615 If you are unsure how to answer this question, answer N.
1617 config ARCH_PROC_KCORE_TEXT
1619 depends on X86_64 && PROC_KCORE
1621 config ILLEGAL_POINTER_VALUE
1624 default 0xdead000000000000 if X86_64
1626 config X86_PMEM_LEGACY_DEVICE
1629 config X86_PMEM_LEGACY
1630 tristate "Support non-standard NVDIMMs and ADR protected memory"
1631 depends on PHYS_ADDR_T_64BIT
1633 select X86_PMEM_LEGACY_DEVICE
1634 select NUMA_KEEP_MEMINFO if NUMA
1637 Treat memory marked using the non-standard e820 type of 12 as used
1638 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1639 The kernel will offer these regions to the 'pmem' driver so
1640 they can be used for persistent storage.
1645 bool "Allocate 3rd-level pagetables from highmem"
1648 The VM uses one page table entry for each page of physical memory.
1649 For systems with a lot of RAM, this can be wasteful of precious
1650 low memory. Setting this option will put user-space page table
1651 entries in high memory.
1653 config X86_CHECK_BIOS_CORRUPTION
1654 bool "Check for low memory corruption"
1656 Periodically check for memory corruption in low memory, which
1657 is suspected to be caused by BIOS. Even when enabled in the
1658 configuration, it is disabled at runtime. Enable it by
1659 setting "memory_corruption_check=1" on the kernel command
1660 line. By default it scans the low 64k of memory every 60
1661 seconds; see the memory_corruption_check_size and
1662 memory_corruption_check_period parameters in
1663 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1665 When enabled with the default parameters, this option has
1666 almost no overhead, as it reserves a relatively small amount
1667 of memory and scans it infrequently. It both detects corruption
1668 and prevents it from affecting the running system.
1670 It is, however, intended as a diagnostic tool; if repeatable
1671 BIOS-originated corruption always affects the same memory,
1672 you can use memmap= to prevent the kernel from using that
1675 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1676 bool "Set the default setting of memory_corruption_check"
1677 depends on X86_CHECK_BIOS_CORRUPTION
1680 Set whether the default state of memory_corruption_check is
1683 config MATH_EMULATION
1685 depends on MODIFY_LDT_SYSCALL
1686 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1688 Linux can emulate a math coprocessor (used for floating point
1689 operations) if you don't have one. 486DX and Pentium processors have
1690 a math coprocessor built in, 486SX and 386 do not, unless you added
1691 a 487DX or 387, respectively. (The messages during boot time can
1692 give you some hints here ["man dmesg"].) Everyone needs either a
1693 coprocessor or this emulation.
1695 If you don't have a math coprocessor, you need to say Y here; if you
1696 say Y here even though you have a coprocessor, the coprocessor will
1697 be used nevertheless. (This behavior can be changed with the kernel
1698 command line option "no387", which comes handy if your coprocessor
1699 is broken. Try "man bootparam" or see the documentation of your boot
1700 loader (lilo or loadlin) about how to pass options to the kernel at
1701 boot time.) This means that it is a good idea to say Y here if you
1702 intend to use this kernel on different machines.
1704 More information about the internals of the Linux math coprocessor
1705 emulation can be found in <file:arch/x86/math-emu/README>.
1707 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1708 kernel, it won't hurt.
1712 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1714 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1715 the Memory Type Range Registers (MTRRs) may be used to control
1716 processor access to memory ranges. This is most useful if you have
1717 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1718 allows bus write transfers to be combined into a larger transfer
1719 before bursting over the PCI/AGP bus. This can increase performance
1720 of image write operations 2.5 times or more. Saying Y here creates a
1721 /proc/mtrr file which may be used to manipulate your processor's
1722 MTRRs. Typically the X server should use this.
1724 This code has a reasonably generic interface so that similar
1725 control registers on other processors can be easily supported
1728 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1729 Registers (ARRs) which provide a similar functionality to MTRRs. For
1730 these, the ARRs are used to emulate the MTRRs.
1731 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1732 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1733 write-combining. All of these processors are supported by this code
1734 and it makes sense to say Y here if you have one of them.
1736 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1737 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1738 can lead to all sorts of problems, so it's good to say Y here.
1740 You can safely say Y even if your machine doesn't have MTRRs, you'll
1741 just add about 9 KB to your kernel.
1743 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1745 config MTRR_SANITIZER
1747 prompt "MTRR cleanup support"
1750 Convert MTRR layout from continuous to discrete, so X drivers can
1751 add writeback entries.
1753 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1754 The largest mtrr entry size for a continuous block can be set with
1759 config MTRR_SANITIZER_ENABLE_DEFAULT
1760 int "MTRR cleanup enable value (0-1)"
1763 depends on MTRR_SANITIZER
1765 Enable mtrr cleanup default value
1767 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1768 int "MTRR cleanup spare reg num (0-7)"
1771 depends on MTRR_SANITIZER
1773 mtrr cleanup spare entries default, it can be changed via
1774 mtrr_spare_reg_nr=N on the kernel command line.
1778 prompt "x86 PAT support" if EXPERT
1781 Use PAT attributes to setup page level cache control.
1783 PATs are the modern equivalents of MTRRs and are much more
1784 flexible than MTRRs.
1786 Say N here if you see bootup problems (boot crash, boot hang,
1787 spontaneous reboots) or a non-working video driver.
1791 config ARCH_USES_PG_UNCACHED
1797 prompt "User Mode Instruction Prevention" if EXPERT
1799 User Mode Instruction Prevention (UMIP) is a security feature in
1800 some x86 processors. If enabled, a general protection fault is
1801 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1802 executed in user mode. These instructions unnecessarily expose
1803 information about the hardware state.
1805 The vast majority of applications do not use these instructions.
1806 For the very few that do, software emulation is provided in
1807 specific cases in protected and virtual-8086 modes. Emulated
1811 # GCC >= 9 and binutils >= 2.29
1812 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1814 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1815 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1816 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1817 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1823 CET features configured (Shadow stack or IBT)
1825 config X86_KERNEL_IBT
1826 prompt "Indirect Branch Tracking"
1828 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1829 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1830 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1834 Build the kernel with support for Indirect Branch Tracking, a
1835 hardware support course-grain forward-edge Control Flow Integrity
1836 protection. It enforces that all indirect calls must land on
1837 an ENDBR instruction, as such, the compiler will instrument the
1838 code with them to make this happen.
1840 In addition to building the kernel with IBT, seal all functions that
1841 are not indirect call targets, avoiding them ever becoming one.
1843 This requires LTO like objtool runs and will slow down the build. It
1844 does significantly reduce the number of ENDBR instructions in the
1847 config X86_INTEL_MEMORY_PROTECTION_KEYS
1848 prompt "Memory Protection Keys"
1850 # Note: only available in 64-bit mode
1851 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1852 select ARCH_USES_HIGH_VMA_FLAGS
1853 select ARCH_HAS_PKEYS
1855 Memory Protection Keys provides a mechanism for enforcing
1856 page-based protections, but without requiring modification of the
1857 page tables when an application changes protection domains.
1859 For details, see Documentation/core-api/protection-keys.rst
1864 prompt "TSX enable mode"
1865 depends on CPU_SUP_INTEL
1866 default X86_INTEL_TSX_MODE_OFF
1868 Intel's TSX (Transactional Synchronization Extensions) feature
1869 allows to optimize locking protocols through lock elision which
1870 can lead to a noticeable performance boost.
1872 On the other hand it has been shown that TSX can be exploited
1873 to form side channel attacks (e.g. TAA) and chances are there
1874 will be more of those attacks discovered in the future.
1876 Therefore TSX is not enabled by default (aka tsx=off). An admin
1877 might override this decision by tsx=on the command line parameter.
1878 Even with TSX enabled, the kernel will attempt to enable the best
1879 possible TAA mitigation setting depending on the microcode available
1880 for the particular machine.
1882 This option allows to set the default tsx mode between tsx=on, =off
1883 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1886 Say off if not sure, auto if TSX is in use but it should be used on safe
1887 platforms or on if TSX is in use and the security aspect of tsx is not
1890 config X86_INTEL_TSX_MODE_OFF
1893 TSX is disabled if possible - equals to tsx=off command line parameter.
1895 config X86_INTEL_TSX_MODE_ON
1898 TSX is always enabled on TSX capable HW - equals the tsx=on command
1901 config X86_INTEL_TSX_MODE_AUTO
1904 TSX is enabled on TSX capable HW that is believed to be safe against
1905 side channel attacks- equals the tsx=auto command line parameter.
1909 bool "Software Guard eXtensions (SGX)"
1910 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1912 depends on CRYPTO_SHA256=y
1914 select NUMA_KEEP_MEMINFO if NUMA
1917 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1918 that can be used by applications to set aside private regions of code
1919 and data, referred to as enclaves. An enclave's private memory can
1920 only be accessed by code running within the enclave. Accesses from
1921 outside the enclave, including other enclaves, are disallowed by
1926 config X86_USER_SHADOW_STACK
1927 bool "X86 userspace shadow stack"
1930 select ARCH_USES_HIGH_VMA_FLAGS
1933 Shadow stack protection is a hardware feature that detects function
1934 return address corruption. This helps mitigate ROP attacks.
1935 Applications must be enabled to use it, and old userspace does not
1936 get protection "for free".
1938 CPUs supporting shadow stacks were first released in 2020.
1940 See Documentation/arch/x86/shstk.rst for more information.
1945 bool "EFI runtime service support"
1948 select EFI_RUNTIME_WRAPPERS
1949 select ARCH_USE_MEMREMAP_PROT
1950 select EFI_RUNTIME_MAP if KEXEC_CORE
1952 This enables the kernel to use EFI runtime services that are
1953 available (such as the EFI variable services).
1955 This option is only useful on systems that have EFI firmware.
1956 In addition, you should use the latest ELILO loader available
1957 at <http://elilo.sourceforge.net> in order to take advantage
1958 of EFI runtime services. However, even with this option, the
1959 resultant kernel should continue to boot on existing non-EFI
1963 bool "EFI stub support"
1967 This kernel feature allows a bzImage to be loaded directly
1968 by EFI firmware without the use of a bootloader.
1970 See Documentation/admin-guide/efi-stub.rst for more information.
1972 config EFI_HANDOVER_PROTOCOL
1973 bool "EFI handover protocol (DEPRECATED)"
1977 Select this in order to include support for the deprecated EFI
1978 handover protocol, which defines alternative entry points into the
1979 EFI stub. This is a practice that has no basis in the UEFI
1980 specification, and requires a priori knowledge on the part of the
1981 bootloader about Linux/x86 specific ways of passing the command line
1982 and initrd, and where in memory those assets may be loaded.
1984 If in doubt, say Y. Even though the corresponding support is not
1985 present in upstream GRUB or other bootloaders, most distros build
1986 GRUB with numerous downstream patches applied, and may rely on the
1987 handover protocol as as result.
1990 bool "EFI mixed-mode support"
1991 depends on EFI_STUB && X86_64
1993 Enabling this feature allows a 64-bit kernel to be booted
1994 on a 32-bit firmware, provided that your CPU supports 64-bit
1997 Note that it is not possible to boot a mixed-mode enabled
1998 kernel via the EFI boot stub - a bootloader that supports
1999 the EFI handover protocol must be used.
2003 config EFI_FAKE_MEMMAP
2004 bool "Enable EFI fake memory map"
2007 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2008 this parameter, you can add arbitrary attribute to specific memory
2009 range by updating original (firmware provided) EFI memmap. This is
2010 useful for debugging of EFI memmap related feature, e.g., Address
2011 Range Mirroring feature.
2013 config EFI_MAX_FAKE_MEM
2014 int "maximum allowable number of ranges in efi_fake_mem boot option"
2015 depends on EFI_FAKE_MEMMAP
2019 Maximum allowable number of ranges in efi_fake_mem boot option.
2020 Ranges can be set up to this value using comma-separated list.
2021 The default value is 8.
2023 config EFI_RUNTIME_MAP
2024 bool "Export EFI runtime maps to sysfs" if EXPERT
2027 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2028 That memory map is required by the 2nd kernel to set up EFI virtual
2029 mappings after kexec, but can also be used for debugging purposes.
2031 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2033 source "kernel/Kconfig.hz"
2035 config ARCH_SUPPORTS_KEXEC
2038 config ARCH_SUPPORTS_KEXEC_FILE
2041 config ARCH_SELECTS_KEXEC_FILE
2043 depends on KEXEC_FILE
2044 select HAVE_IMA_KEXEC if IMA
2046 config ARCH_SUPPORTS_KEXEC_PURGATORY
2049 config ARCH_SUPPORTS_KEXEC_SIG
2052 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2055 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2058 config ARCH_SUPPORTS_KEXEC_JUMP
2061 config ARCH_SUPPORTS_CRASH_DUMP
2062 def_bool X86_64 || (X86_32 && HIGHMEM)
2064 config ARCH_SUPPORTS_CRASH_HOTPLUG
2067 config PHYSICAL_START
2068 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2071 This gives the physical address where the kernel is loaded.
2073 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2074 bzImage will decompress itself to above physical address and
2075 run from there. Otherwise, bzImage will run from the address where
2076 it has been loaded by the boot loader and will ignore above physical
2079 In normal kdump cases one does not have to set/change this option
2080 as now bzImage can be compiled as a completely relocatable image
2081 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2082 address. This option is mainly useful for the folks who don't want
2083 to use a bzImage for capturing the crash dump and want to use a
2084 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2085 to be specifically compiled to run from a specific memory area
2086 (normally a reserved region) and this option comes handy.
2088 So if you are using bzImage for capturing the crash dump,
2089 leave the value here unchanged to 0x1000000 and set
2090 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2091 for capturing the crash dump change this value to start of
2092 the reserved region. In other words, it can be set based on
2093 the "X" value as specified in the "crashkernel=YM@XM"
2094 command line boot parameter passed to the panic-ed
2095 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2096 for more details about crash dumps.
2098 Usage of bzImage for capturing the crash dump is recommended as
2099 one does not have to build two kernels. Same kernel can be used
2100 as production kernel and capture kernel. Above option should have
2101 gone away after relocatable bzImage support is introduced. But it
2102 is present because there are users out there who continue to use
2103 vmlinux for dump capture. This option should go away down the
2106 Don't change this unless you know what you are doing.
2109 bool "Build a relocatable kernel"
2112 This builds a kernel image that retains relocation information
2113 so it can be loaded someplace besides the default 1MB.
2114 The relocations tend to make the kernel binary about 10% larger,
2115 but are discarded at runtime.
2117 One use is for the kexec on panic case where the recovery kernel
2118 must live at a different physical address than the primary
2121 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2122 it has been loaded at and the compile time physical address
2123 (CONFIG_PHYSICAL_START) is used as the minimum location.
2125 config RANDOMIZE_BASE
2126 bool "Randomize the address of the kernel image (KASLR)"
2127 depends on RELOCATABLE
2130 In support of Kernel Address Space Layout Randomization (KASLR),
2131 this randomizes the physical address at which the kernel image
2132 is decompressed and the virtual address where the kernel
2133 image is mapped, as a security feature that deters exploit
2134 attempts relying on knowledge of the location of kernel
2137 On 64-bit, the kernel physical and virtual addresses are
2138 randomized separately. The physical address will be anywhere
2139 between 16MB and the top of physical memory (up to 64TB). The
2140 virtual address will be randomized from 16MB up to 1GB (9 bits
2141 of entropy). Note that this also reduces the memory space
2142 available to kernel modules from 1.5GB to 1GB.
2144 On 32-bit, the kernel physical and virtual addresses are
2145 randomized together. They will be randomized from 16MB up to
2146 512MB (8 bits of entropy).
2148 Entropy is generated using the RDRAND instruction if it is
2149 supported. If RDTSC is supported, its value is mixed into
2150 the entropy pool as well. If neither RDRAND nor RDTSC are
2151 supported, then entropy is read from the i8254 timer. The
2152 usable entropy is limited by the kernel being built using
2153 2GB addressing, and that PHYSICAL_ALIGN must be at a
2154 minimum of 2MB. As a result, only 10 bits of entropy are
2155 theoretically possible, but the implementations are further
2156 limited due to memory layouts.
2160 # Relocation on x86 needs some additional build support
2161 config X86_NEED_RELOCS
2163 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2165 config PHYSICAL_ALIGN
2166 hex "Alignment value to which kernel should be aligned"
2168 range 0x2000 0x1000000 if X86_32
2169 range 0x200000 0x1000000 if X86_64
2171 This value puts the alignment restrictions on physical address
2172 where kernel is loaded and run from. Kernel is compiled for an
2173 address which meets above alignment restriction.
2175 If bootloader loads the kernel at a non-aligned address and
2176 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2177 address aligned to above value and run from there.
2179 If bootloader loads the kernel at a non-aligned address and
2180 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2181 load address and decompress itself to the address it has been
2182 compiled for and run from there. The address for which kernel is
2183 compiled already meets above alignment restrictions. Hence the
2184 end result is that kernel runs from a physical address meeting
2185 above alignment restrictions.
2187 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2188 this value must be a multiple of 0x200000.
2190 Don't change this unless you know what you are doing.
2192 config DYNAMIC_MEMORY_LAYOUT
2195 This option makes base addresses of vmalloc and vmemmap as well as
2196 __PAGE_OFFSET movable during boot.
2198 config RANDOMIZE_MEMORY
2199 bool "Randomize the kernel memory sections"
2201 depends on RANDOMIZE_BASE
2202 select DYNAMIC_MEMORY_LAYOUT
2203 default RANDOMIZE_BASE
2205 Randomizes the base virtual address of kernel memory sections
2206 (physical memory mapping, vmalloc & vmemmap). This security feature
2207 makes exploits relying on predictable memory locations less reliable.
2209 The order of allocations remains unchanged. Entropy is generated in
2210 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2211 configuration have in average 30,000 different possible virtual
2212 addresses for each memory section.
2216 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2217 hex "Physical memory mapping padding" if EXPERT
2218 depends on RANDOMIZE_MEMORY
2219 default "0xa" if MEMORY_HOTPLUG
2221 range 0x1 0x40 if MEMORY_HOTPLUG
2224 Define the padding in terabytes added to the existing physical
2225 memory size during kernel memory randomization. It is useful
2226 for memory hotplug support but reduces the entropy available for
2227 address randomization.
2229 If unsure, leave at the default value.
2231 config ADDRESS_MASKING
2232 bool "Linear Address Masking support"
2235 Linear Address Masking (LAM) modifies the checking that is applied
2236 to 64-bit linear addresses, allowing software to use of the
2237 untranslated address bits for metadata.
2239 The capability can be used for efficient address sanitizers (ASAN)
2240 implementation and for optimizations in JITs.
2248 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2249 depends on COMPAT_32
2251 Certain buggy versions of glibc will crash if they are
2252 presented with a 32-bit vDSO that is not mapped at the address
2253 indicated in its segment table.
2255 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2256 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2257 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2258 the only released version with the bug, but OpenSUSE 9
2259 contains a buggy "glibc 2.3.2".
2261 The symptom of the bug is that everything crashes on startup, saying:
2262 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2264 Saying Y here changes the default value of the vdso32 boot
2265 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2266 This works around the glibc bug but hurts performance.
2268 If unsure, say N: if you are compiling your own kernel, you
2269 are unlikely to be using a buggy version of glibc.
2272 prompt "vsyscall table for legacy applications"
2274 default LEGACY_VSYSCALL_XONLY
2276 Legacy user code that does not know how to find the vDSO expects
2277 to be able to issue three syscalls by calling fixed addresses in
2278 kernel space. Since this location is not randomized with ASLR,
2279 it can be used to assist security vulnerability exploitation.
2281 This setting can be changed at boot time via the kernel command
2282 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2283 is deprecated and can only be enabled using the kernel command
2286 On a system with recent enough glibc (2.14 or newer) and no
2287 static binaries, you can say None without a performance penalty
2288 to improve security.
2290 If unsure, select "Emulate execution only".
2292 config LEGACY_VSYSCALL_XONLY
2293 bool "Emulate execution only"
2295 The kernel traps and emulates calls into the fixed vsyscall
2296 address mapping and does not allow reads. This
2297 configuration is recommended when userspace might use the
2298 legacy vsyscall area but support for legacy binary
2299 instrumentation of legacy code is not needed. It mitigates
2300 certain uses of the vsyscall area as an ASLR-bypassing
2303 config LEGACY_VSYSCALL_NONE
2306 There will be no vsyscall mapping at all. This will
2307 eliminate any risk of ASLR bypass due to the vsyscall
2308 fixed address mapping. Attempts to use the vsyscalls
2309 will be reported to dmesg, so that either old or
2310 malicious userspace programs can be identified.
2315 bool "Built-in kernel command line"
2317 Allow for specifying boot arguments to the kernel at
2318 build time. On some systems (e.g. embedded ones), it is
2319 necessary or convenient to provide some or all of the
2320 kernel boot arguments with the kernel itself (that is,
2321 to not rely on the boot loader to provide them.)
2323 To compile command line arguments into the kernel,
2324 set this option to 'Y', then fill in the
2325 boot arguments in CONFIG_CMDLINE.
2327 Systems with fully functional boot loaders (i.e. non-embedded)
2328 should leave this option set to 'N'.
2331 string "Built-in kernel command string"
2332 depends on CMDLINE_BOOL
2335 Enter arguments here that should be compiled into the kernel
2336 image and used at boot time. If the boot loader provides a
2337 command line at boot time, it is appended to this string to
2338 form the full kernel command line, when the system boots.
2340 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2341 change this behavior.
2343 In most cases, the command line (whether built-in or provided
2344 by the boot loader) should specify the device for the root
2347 config CMDLINE_OVERRIDE
2348 bool "Built-in command line overrides boot loader arguments"
2349 depends on CMDLINE_BOOL && CMDLINE != ""
2351 Set this option to 'Y' to have the kernel ignore the boot loader
2352 command line, and use ONLY the built-in command line.
2354 This is used to work around broken boot loaders. This should
2355 be set to 'N' under normal conditions.
2357 config MODIFY_LDT_SYSCALL
2358 bool "Enable the LDT (local descriptor table)" if EXPERT
2361 Linux can allow user programs to install a per-process x86
2362 Local Descriptor Table (LDT) using the modify_ldt(2) system
2363 call. This is required to run 16-bit or segmented code such as
2364 DOSEMU or some Wine programs. It is also used by some very old
2365 threading libraries.
2367 Enabling this feature adds a small amount of overhead to
2368 context switches and increases the low-level kernel attack
2369 surface. Disabling it removes the modify_ldt(2) system call.
2371 Saying 'N' here may make sense for embedded or server kernels.
2373 config STRICT_SIGALTSTACK_SIZE
2374 bool "Enforce strict size checking for sigaltstack"
2375 depends on DYNAMIC_SIGFRAME
2377 For historical reasons MINSIGSTKSZ is a constant which became
2378 already too small with AVX512 support. Add a mechanism to
2379 enforce strict checking of the sigaltstack size against the
2380 real size of the FPU frame. This option enables the check
2381 by default. It can also be controlled via the kernel command
2382 line option 'strict_sas_size' independent of this config
2383 switch. Enabling it might break existing applications which
2384 allocate a too small sigaltstack but 'work' because they
2385 never get a signal delivered.
2387 Say 'N' unless you want to really enforce this check.
2389 source "kernel/livepatch/Kconfig"
2394 def_bool $(cc-option,-mharden-sls=all)
2396 config CC_HAS_RETURN_THUNK
2397 def_bool $(cc-option,-mfunction-return=thunk-extern)
2399 config CC_HAS_ENTRY_PADDING
2400 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2402 config FUNCTION_PADDING_CFI
2404 default 59 if FUNCTION_ALIGNMENT_64B
2405 default 27 if FUNCTION_ALIGNMENT_32B
2406 default 11 if FUNCTION_ALIGNMENT_16B
2407 default 3 if FUNCTION_ALIGNMENT_8B
2410 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2411 # except Kconfig can't do arithmetic :/
2412 config FUNCTION_PADDING_BYTES
2414 default FUNCTION_PADDING_CFI if CFI_CLANG
2415 default FUNCTION_ALIGNMENT
2419 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2420 select FUNCTION_ALIGNMENT_16B
2424 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2427 config HAVE_CALL_THUNKS
2429 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2435 config PREFIX_SYMBOLS
2437 depends on CALL_PADDING && !CFI_CLANG
2439 menuconfig SPECULATION_MITIGATIONS
2440 bool "Mitigations for speculative execution vulnerabilities"
2443 Say Y here to enable options which enable mitigations for
2444 speculative execution hardware vulnerabilities.
2446 If you say N, all mitigations will be disabled. You really
2447 should know what you are doing to say so.
2449 if SPECULATION_MITIGATIONS
2451 config PAGE_TABLE_ISOLATION
2452 bool "Remove the kernel mapping in user mode"
2454 depends on (X86_64 || X86_PAE)
2456 This feature reduces the number of hardware side channels by
2457 ensuring that the majority of kernel addresses are not mapped
2460 See Documentation/arch/x86/pti.rst for more details.
2463 bool "Avoid speculative indirect branches in kernel"
2464 select OBJTOOL if HAVE_OBJTOOL
2467 Compile kernel with the retpoline compiler options to guard against
2468 kernel-to-user data leaks by avoiding speculative indirect
2469 branches. Requires a compiler with -mindirect-branch=thunk-extern
2470 support for full protection. The kernel may run slower.
2473 bool "Enable return-thunks"
2474 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2475 select OBJTOOL if HAVE_OBJTOOL
2478 Compile the kernel with the return-thunks compiler option to guard
2479 against kernel-to-user data leaks by avoiding return speculation.
2480 Requires a compiler with -mfunction-return=thunk-extern
2481 support for full protection. The kernel may run slower.
2483 config CPU_UNRET_ENTRY
2484 bool "Enable UNRET on kernel entry"
2485 depends on CPU_SUP_AMD && RETHUNK && X86_64
2488 Compile the kernel with support for the retbleed=unret mitigation.
2490 config CALL_DEPTH_TRACKING
2491 bool "Mitigate RSB underflow with call depth tracking"
2492 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2493 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2497 Compile the kernel with call depth tracking to mitigate the Intel
2498 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2499 mitigation is off by default and needs to be enabled on the
2500 kernel command line via the retbleed=stuff option. For
2501 non-affected systems the overhead of this option is marginal as
2502 the call depth tracking is using run-time generated call thunks
2503 in a compiler generated padding area and call patching. This
2504 increases text size by ~5%. For non affected systems this space
2505 is unused. On affected SKL systems this results in a significant
2506 performance gain over the IBRS mitigation.
2508 config CALL_THUNKS_DEBUG
2509 bool "Enable call thunks and call depth tracking debugging"
2510 depends on CALL_DEPTH_TRACKING
2511 select FUNCTION_ALIGNMENT_32B
2514 Enable call/ret counters for imbalance detection and build in
2515 a noisy dmesg about callthunks generation and call patching for
2516 trouble shooting. The debug prints need to be enabled on the
2517 kernel command line with 'debug-callthunks'.
2518 Only enable this when you are debugging call thunks as this
2519 creates a noticeable runtime overhead. If unsure say N.
2521 config CPU_IBPB_ENTRY
2522 bool "Enable IBPB on kernel entry"
2523 depends on CPU_SUP_AMD && X86_64
2526 Compile the kernel with support for the retbleed=ibpb mitigation.
2528 config CPU_IBRS_ENTRY
2529 bool "Enable IBRS on kernel entry"
2530 depends on CPU_SUP_INTEL && X86_64
2533 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2534 This mitigates both spectre_v2 and retbleed at great cost to
2538 bool "Mitigate speculative RAS overflow on AMD"
2539 depends on CPU_SUP_AMD && X86_64 && RETHUNK
2542 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2545 bool "Mitigate Straight-Line-Speculation"
2546 depends on CC_HAS_SLS && X86_64
2547 select OBJTOOL if HAVE_OBJTOOL
2550 Compile the kernel with straight-line-speculation options to guard
2551 against straight line speculation. The kernel image might be slightly
2554 config GDS_FORCE_MITIGATION
2555 bool "Force GDS Mitigation"
2556 depends on CPU_SUP_INTEL
2559 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2560 unprivileged speculative access to data which was previously stored in
2563 This option is equivalent to setting gather_data_sampling=force on the
2564 command line. The microcode mitigation is used if present, otherwise
2565 AVX is disabled as a mitigation. On affected systems that are missing
2566 the microcode any userspace code that unconditionally uses AVX will
2567 break with this option set.
2569 Setting this option on systems not vulnerable to GDS has no effect.
2575 config ARCH_HAS_ADD_PAGES
2577 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2579 menu "Power management and ACPI options"
2581 config ARCH_HIBERNATION_HEADER
2583 depends on HIBERNATION
2585 source "kernel/power/Kconfig"
2587 source "drivers/acpi/Kconfig"
2594 tristate "APM (Advanced Power Management) BIOS support"
2595 depends on X86_32 && PM_SLEEP
2597 APM is a BIOS specification for saving power using several different
2598 techniques. This is mostly useful for battery powered laptops with
2599 APM compliant BIOSes. If you say Y here, the system time will be
2600 reset after a RESUME operation, the /proc/apm device will provide
2601 battery status information, and user-space programs will receive
2602 notification of APM "events" (e.g. battery status change).
2604 If you select "Y" here, you can disable actual use of the APM
2605 BIOS by passing the "apm=off" option to the kernel at boot time.
2607 Note that the APM support is almost completely disabled for
2608 machines with more than one CPU.
2610 In order to use APM, you will need supporting software. For location
2611 and more information, read <file:Documentation/power/apm-acpi.rst>
2612 and the Battery Powered Linux mini-HOWTO, available from
2613 <http://www.tldp.org/docs.html#howto>.
2615 This driver does not spin down disk drives (see the hdparm(8)
2616 manpage ("man 8 hdparm") for that), and it doesn't turn off
2617 VESA-compliant "green" monitors.
2619 This driver does not support the TI 4000M TravelMate and the ACER
2620 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2621 desktop machines also don't have compliant BIOSes, and this driver
2622 may cause those machines to panic during the boot phase.
2624 Generally, if you don't have a battery in your machine, there isn't
2625 much point in using this driver and you should say N. If you get
2626 random kernel OOPSes or reboots that don't seem to be related to
2627 anything, try disabling/enabling this option (or disabling/enabling
2630 Some other things you should try when experiencing seemingly random,
2633 1) make sure that you have enough swap space and that it is
2635 2) pass the "idle=poll" option to the kernel
2636 3) switch on floating point emulation in the kernel and pass
2637 the "no387" option to the kernel
2638 4) pass the "floppy=nodma" option to the kernel
2639 5) pass the "mem=4M" option to the kernel (thereby disabling
2640 all but the first 4 MB of RAM)
2641 6) make sure that the CPU is not over clocked.
2642 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2643 8) disable the cache from your BIOS settings
2644 9) install a fan for the video card or exchange video RAM
2645 10) install a better fan for the CPU
2646 11) exchange RAM chips
2647 12) exchange the motherboard.
2649 To compile this driver as a module, choose M here: the
2650 module will be called apm.
2654 config APM_IGNORE_USER_SUSPEND
2655 bool "Ignore USER SUSPEND"
2657 This option will ignore USER SUSPEND requests. On machines with a
2658 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2659 series notebooks, it is necessary to say Y because of a BIOS bug.
2661 config APM_DO_ENABLE
2662 bool "Enable PM at boot time"
2664 Enable APM features at boot time. From page 36 of the APM BIOS
2665 specification: "When disabled, the APM BIOS does not automatically
2666 power manage devices, enter the Standby State, enter the Suspend
2667 State, or take power saving steps in response to CPU Idle calls."
2668 This driver will make CPU Idle calls when Linux is idle (unless this
2669 feature is turned off -- see "Do CPU IDLE calls", below). This
2670 should always save battery power, but more complicated APM features
2671 will be dependent on your BIOS implementation. You may need to turn
2672 this option off if your computer hangs at boot time when using APM
2673 support, or if it beeps continuously instead of suspending. Turn
2674 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2675 T400CDT. This is off by default since most machines do fine without
2680 bool "Make CPU Idle calls when idle"
2682 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2683 On some machines, this can activate improved power savings, such as
2684 a slowed CPU clock rate, when the machine is idle. These idle calls
2685 are made after the idle loop has run for some length of time (e.g.,
2686 333 mS). On some machines, this will cause a hang at boot time or
2687 whenever the CPU becomes idle. (On machines with more than one CPU,
2688 this option does nothing.)
2690 config APM_DISPLAY_BLANK
2691 bool "Enable console blanking using APM"
2693 Enable console blanking using the APM. Some laptops can use this to
2694 turn off the LCD backlight when the screen blanker of the Linux
2695 virtual console blanks the screen. Note that this is only used by
2696 the virtual console screen blanker, and won't turn off the backlight
2697 when using the X Window system. This also doesn't have anything to
2698 do with your VESA-compliant power-saving monitor. Further, this
2699 option doesn't work for all laptops -- it might not turn off your
2700 backlight at all, or it might print a lot of errors to the console,
2701 especially if you are using gpm.
2703 config APM_ALLOW_INTS
2704 bool "Allow interrupts during APM BIOS calls"
2706 Normally we disable external interrupts while we are making calls to
2707 the APM BIOS as a measure to lessen the effects of a badly behaving
2708 BIOS implementation. The BIOS should reenable interrupts if it
2709 needs to. Unfortunately, some BIOSes do not -- especially those in
2710 many of the newer IBM Thinkpads. If you experience hangs when you
2711 suspend, try setting this to Y. Otherwise, say N.
2715 source "drivers/cpufreq/Kconfig"
2717 source "drivers/cpuidle/Kconfig"
2719 source "drivers/idle/Kconfig"
2723 menu "Bus options (PCI etc.)"
2726 prompt "PCI access mode"
2727 depends on X86_32 && PCI
2730 On PCI systems, the BIOS can be used to detect the PCI devices and
2731 determine their configuration. However, some old PCI motherboards
2732 have BIOS bugs and may crash if this is done. Also, some embedded
2733 PCI-based systems don't have any BIOS at all. Linux can also try to
2734 detect the PCI hardware directly without using the BIOS.
2736 With this option, you can specify how Linux should detect the
2737 PCI devices. If you choose "BIOS", the BIOS will be used,
2738 if you choose "Direct", the BIOS won't be used, and if you
2739 choose "MMConfig", then PCI Express MMCONFIG will be used.
2740 If you choose "Any", the kernel will try MMCONFIG, then the
2741 direct access method and falls back to the BIOS if that doesn't
2742 work. If unsure, go with the default, which is "Any".
2747 config PCI_GOMMCONFIG
2764 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2766 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2769 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2772 bool "Support mmconfig PCI config space access" if X86_64
2774 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2775 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2779 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2783 depends on PCI && XEN
2785 config MMCONF_FAM10H
2787 depends on X86_64 && PCI_MMCONFIG && ACPI
2789 config PCI_CNB20LE_QUIRK
2790 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2793 Read the PCI windows out of the CNB20LE host bridge. This allows
2794 PCI hotplug to work on systems with the CNB20LE chipset which do
2797 There's no public spec for this chipset, and this functionality
2798 is known to be incomplete.
2800 You should say N unless you know you need this.
2803 bool "ISA bus support on modern systems" if EXPERT
2805 Expose ISA bus device drivers and options available for selection and
2806 configuration. Enable this option if your target machine has an ISA
2807 bus. ISA is an older system, displaced by PCI and newer bus
2808 architectures -- if your target machine is modern, it probably does
2809 not have an ISA bus.
2813 # x86_64 have no ISA slots, but can have ISA-style DMA.
2815 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2818 Enables ISA-style DMA support for devices requiring such controllers.
2826 Find out whether you have ISA slots on your motherboard. ISA is the
2827 name of a bus system, i.e. the way the CPU talks to the other stuff
2828 inside your box. Other bus systems are PCI, EISA, MicroChannel
2829 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2830 newer boards don't support it. If you have ISA, say Y, otherwise N.
2833 tristate "NatSemi SCx200 support"
2835 This provides basic support for National Semiconductor's
2836 (now AMD's) Geode processors. The driver probes for the
2837 PCI-IDs of several on-chip devices, so its a good dependency
2838 for other scx200_* drivers.
2840 If compiled as a module, the driver is named scx200.
2842 config SCx200HR_TIMER
2843 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2847 This driver provides a clocksource built upon the on-chip
2848 27MHz high-resolution timer. Its also a workaround for
2849 NSC Geode SC-1100's buggy TSC, which loses time when the
2850 processor goes idle (as is done by the scheduler). The
2851 other workaround is idle=poll boot option.
2854 bool "One Laptop Per Child support"
2862 Add support for detecting the unique features of the OLPC
2866 bool "OLPC XO-1 Power Management"
2867 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2869 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2872 bool "OLPC XO-1 Real Time Clock"
2873 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2875 Add support for the XO-1 real time clock, which can be used as a
2876 programmable wakeup source.
2879 bool "OLPC XO-1 SCI extras"
2880 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2884 Add support for SCI-based features of the OLPC XO-1 laptop:
2885 - EC-driven system wakeups
2889 - AC adapter status updates
2890 - Battery status updates
2892 config OLPC_XO15_SCI
2893 bool "OLPC XO-1.5 SCI extras"
2894 depends on OLPC && ACPI
2897 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2898 - EC-driven system wakeups
2899 - AC adapter status updates
2900 - Battery status updates
2903 bool "PCEngines ALIX System Support (LED setup)"
2906 This option enables system support for the PCEngines ALIX.
2907 At present this just sets up LEDs for GPIO control on
2908 ALIX2/3/6 boards. However, other system specific setup should
2911 Note: You must still enable the drivers for GPIO and LED support
2912 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2914 Note: You have to set alix.force=1 for boards with Award BIOS.
2917 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2920 This option enables system support for the Soekris Engineering net5501.
2923 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2927 This option enables system support for the Traverse Technologies GEOS.
2930 bool "Technologic Systems TS-5500 platform support"
2932 select CHECK_SIGNATURE
2936 This option enables system support for the Technologic Systems TS-5500.
2942 depends on CPU_SUP_AMD && PCI
2946 menu "Binary Emulations"
2948 config IA32_EMULATION
2949 bool "IA32 Emulation"
2951 select ARCH_WANT_OLD_COMPAT_IPC
2953 select COMPAT_OLD_SIGACTION
2955 Include code to run legacy 32-bit programs under a
2956 64-bit kernel. You should likely turn this on, unless you're
2957 100% sure that you don't have any 32-bit programs left.
2960 bool "x32 ABI for 64-bit mode"
2962 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2963 # compressed debug sections to x86_x32 properly:
2964 # https://github.com/ClangBuiltLinux/linux/issues/514
2965 # https://github.com/ClangBuiltLinux/linux/issues/1141
2966 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2968 Include code to run binaries for the x32 native 32-bit ABI
2969 for 64-bit processors. An x32 process gets access to the
2970 full 64-bit register file and wide data path while leaving
2971 pointers at 32 bits for smaller memory footprint.
2975 depends on IA32_EMULATION || X86_32
2977 select OLD_SIGSUSPEND3
2981 depends on IA32_EMULATION || X86_X32_ABI
2983 config COMPAT_FOR_U64_ALIGNMENT
2989 config HAVE_ATOMIC_IOMAP
2993 source "arch/x86/kvm/Kconfig"
2995 source "arch/x86/Kconfig.assembler"