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 HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
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_CPU_PASID if IOMMU_SVA
76 select ARCH_HAS_CURRENT_STACK_POINTER
77 select ARCH_HAS_DEBUG_VIRTUAL
78 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
79 select ARCH_HAS_DEVMEM_IS_ALLOWED
80 select ARCH_HAS_EARLY_DEBUG if KGDB
81 select ARCH_HAS_ELF_RANDOMIZE
82 select ARCH_HAS_FAST_MULTIPLIER
83 select ARCH_HAS_FORTIFY_SOURCE
84 select ARCH_HAS_GCOV_PROFILE_ALL
85 select ARCH_HAS_KCOV if X86_64
86 select ARCH_HAS_MEM_ENCRYPT
87 select ARCH_HAS_MEMBARRIER_SYNC_CORE
88 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
89 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
90 select ARCH_HAS_PMEM_API if X86_64
91 select ARCH_HAS_PTE_DEVMAP if X86_64
92 select ARCH_HAS_PTE_SPECIAL
93 select ARCH_HAS_HW_PTE_YOUNG
94 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
95 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
96 select ARCH_HAS_COPY_MC if X86_64
97 select ARCH_HAS_SET_MEMORY
98 select ARCH_HAS_SET_DIRECT_MAP
99 select ARCH_HAS_STRICT_KERNEL_RWX
100 select ARCH_HAS_STRICT_MODULE_RWX
101 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
102 select ARCH_HAS_SYSCALL_WRAPPER
103 select ARCH_HAS_UBSAN_SANITIZE_ALL
104 select ARCH_HAS_DEBUG_WX
105 select ARCH_HAS_ZONE_DMA_SET if EXPERT
106 select ARCH_HAVE_NMI_SAFE_CMPXCHG
107 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
108 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
109 select ARCH_MIGHT_HAVE_PC_PARPORT
110 select ARCH_MIGHT_HAVE_PC_SERIO
111 select ARCH_STACKWALK
112 select ARCH_SUPPORTS_ACPI
113 select ARCH_SUPPORTS_ATOMIC_RMW
114 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
115 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
116 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
117 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
118 select ARCH_SUPPORTS_CFI_CLANG if X86_64
119 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
120 select ARCH_SUPPORTS_LTO_CLANG
121 select ARCH_SUPPORTS_LTO_CLANG_THIN
122 select ARCH_USE_BUILTIN_BSWAP
123 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
124 select ARCH_USE_MEMTEST
125 select ARCH_USE_QUEUED_RWLOCKS
126 select ARCH_USE_QUEUED_SPINLOCKS
127 select ARCH_USE_SYM_ANNOTATIONS
128 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
129 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
130 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
131 select ARCH_WANTS_NO_INSTR
132 select ARCH_WANT_GENERAL_HUGETLB
133 select ARCH_WANT_HUGE_PMD_SHARE
134 select ARCH_WANT_LD_ORPHAN_WARN
135 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
136 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
137 select ARCH_WANTS_THP_SWAP if X86_64
138 select ARCH_HAS_PARANOID_L1D_FLUSH
139 select BUILDTIME_TABLE_SORT
141 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
142 select CLOCKSOURCE_WATCHDOG
143 # Word-size accesses may read uninitialized data past the trailing \0
144 # in strings and cause false KMSAN reports.
145 select DCACHE_WORD_ACCESS if !KMSAN
146 select DYNAMIC_SIGFRAME
147 select EDAC_ATOMIC_SCRUB
149 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
150 select GENERIC_CLOCKEVENTS_MIN_ADJUST
151 select GENERIC_CMOS_UPDATE
152 select GENERIC_CPU_AUTOPROBE
153 select GENERIC_CPU_DEVICES
154 select GENERIC_CPU_VULNERABILITIES
155 select GENERIC_EARLY_IOREMAP
158 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
159 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
160 select GENERIC_IRQ_MIGRATION if SMP
161 select GENERIC_IRQ_PROBE
162 select GENERIC_IRQ_RESERVATION_MODE
163 select GENERIC_IRQ_SHOW
164 select GENERIC_PENDING_IRQ if SMP
165 select GENERIC_PTDUMP
166 select GENERIC_SMP_IDLE_THREAD
167 select GENERIC_TIME_VSYSCALL
168 select GENERIC_GETTIMEOFDAY
169 select GENERIC_VDSO_TIME_NS
170 select GUP_GET_PXX_LOW_HIGH if X86_PAE
171 select HARDIRQS_SW_RESEND
172 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
174 select HAVE_ACPI_APEI if ACPI
175 select HAVE_ACPI_APEI_NMI if ACPI
176 select HAVE_ALIGNED_STRUCT_PAGE
177 select HAVE_ARCH_AUDITSYSCALL
178 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
179 select HAVE_ARCH_HUGE_VMALLOC if X86_64
180 select HAVE_ARCH_JUMP_LABEL
181 select HAVE_ARCH_JUMP_LABEL_RELATIVE
182 select HAVE_ARCH_KASAN if X86_64
183 select HAVE_ARCH_KASAN_VMALLOC if X86_64
184 select HAVE_ARCH_KFENCE
185 select HAVE_ARCH_KMSAN if X86_64
186 select HAVE_ARCH_KGDB
187 select HAVE_ARCH_MMAP_RND_BITS if MMU
188 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
189 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
190 select HAVE_ARCH_PREL32_RELOCATIONS
191 select HAVE_ARCH_SECCOMP_FILTER
192 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
193 select HAVE_ARCH_STACKLEAK
194 select HAVE_ARCH_TRACEHOOK
195 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
196 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
197 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
198 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
199 select HAVE_ARCH_VMAP_STACK if X86_64
200 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
201 select HAVE_ARCH_WITHIN_STACK_FRAMES
202 select HAVE_ASM_MODVERSIONS
203 select HAVE_CMPXCHG_DOUBLE
204 select HAVE_CMPXCHG_LOCAL
205 select HAVE_CONTEXT_TRACKING_USER if X86_64
206 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
207 select HAVE_C_RECORDMCOUNT
208 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
209 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
210 select HAVE_BUILDTIME_MCOUNT_SORT
211 select HAVE_DEBUG_KMEMLEAK
212 select HAVE_DMA_CONTIGUOUS
213 select HAVE_DYNAMIC_FTRACE
214 select HAVE_DYNAMIC_FTRACE_WITH_REGS
215 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
216 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
217 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
218 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
220 select HAVE_EFFICIENT_UNALIGNED_ACCESS
222 select HAVE_EXIT_THREAD
224 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
225 select HAVE_FTRACE_MCOUNT_RECORD
226 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
227 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
228 select HAVE_FUNCTION_TRACER
229 select HAVE_GCC_PLUGINS
230 select HAVE_HW_BREAKPOINT
231 select HAVE_IOREMAP_PROT
232 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
233 select HAVE_IRQ_TIME_ACCOUNTING
234 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
235 select HAVE_KERNEL_BZIP2
236 select HAVE_KERNEL_GZIP
237 select HAVE_KERNEL_LZ4
238 select HAVE_KERNEL_LZMA
239 select HAVE_KERNEL_LZO
240 select HAVE_KERNEL_XZ
241 select HAVE_KERNEL_ZSTD
243 select HAVE_KPROBES_ON_FTRACE
244 select HAVE_FUNCTION_ERROR_INJECTION
245 select HAVE_KRETPROBES
248 select HAVE_LIVEPATCH if X86_64
249 select HAVE_MIXED_BREAKPOINTS_REGS
250 select HAVE_MOD_ARCH_SPECIFIC
253 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
255 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
256 select HAVE_OBJTOOL if X86_64
257 select HAVE_OPTPROBES
258 select HAVE_PCSPKR_PLATFORM
259 select HAVE_PERF_EVENTS
260 select HAVE_PERF_EVENTS_NMI
261 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
263 select HAVE_PERF_REGS
264 select HAVE_PERF_USER_STACK_DUMP
265 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
266 select MMU_GATHER_MERGE_VMAS
267 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
268 select HAVE_REGS_AND_STACK_ACCESS_API
269 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
270 select HAVE_FUNCTION_ARG_ACCESS_API
271 select HAVE_SETUP_PER_CPU_AREA
272 select HAVE_SOFTIRQ_ON_OWN_STACK
273 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
274 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
275 select HAVE_STATIC_CALL
276 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
277 select HAVE_PREEMPT_DYNAMIC_CALL
279 select HAVE_RUST if X86_64
280 select HAVE_SYSCALL_TRACEPOINTS
281 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
282 select HAVE_UNSTABLE_SCHED_CLOCK
283 select HAVE_USER_RETURN_NOTIFIER
284 select HAVE_GENERIC_VDSO
285 select HOTPLUG_PARALLEL if SMP && X86_64
286 select HOTPLUG_SMT if SMP
287 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
288 select IRQ_FORCED_THREADING
289 select LOCK_MM_AND_FIND_VMA
290 select NEED_PER_CPU_EMBED_FIRST_CHUNK
291 select NEED_PER_CPU_PAGE_FIRST_CHUNK
292 select NEED_SG_DMA_LENGTH
293 select PCI_DOMAINS if PCI
294 select PCI_LOCKLESS_CONFIG if PCI
297 select RTC_MC146818_LIB
299 select SYSCTL_EXCEPTION_TRACE
300 select THREAD_INFO_IN_TASK
301 select TRACE_IRQFLAGS_SUPPORT
302 select TRACE_IRQFLAGS_NMI_SUPPORT
303 select USER_STACKTRACE_SUPPORT
304 select HAVE_ARCH_KCSAN if X86_64
305 select PROC_PID_ARCH_STATUS if PROC_FS
306 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
307 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
308 select FUNCTION_ALIGNMENT_4B
309 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
310 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
312 config INSTRUCTION_DECODER
314 depends on KPROBES || PERF_EVENTS || UPROBES
318 default "elf32-i386" if X86_32
319 default "elf64-x86-64" if X86_64
321 config LOCKDEP_SUPPORT
324 config STACKTRACE_SUPPORT
330 config ARCH_MMAP_RND_BITS_MIN
334 config ARCH_MMAP_RND_BITS_MAX
338 config ARCH_MMAP_RND_COMPAT_BITS_MIN
341 config ARCH_MMAP_RND_COMPAT_BITS_MAX
347 config GENERIC_ISA_DMA
349 depends on ISA_DMA_API
353 default y if KMSAN || KASAN
358 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
360 config GENERIC_BUG_RELATIVE_POINTERS
363 config ARCH_MAY_HAVE_PC_FDC
365 depends on ISA_DMA_API
367 config GENERIC_CALIBRATE_DELAY
370 config ARCH_HAS_CPU_RELAX
373 config ARCH_HIBERNATION_POSSIBLE
376 config ARCH_SUSPEND_POSSIBLE
382 config KASAN_SHADOW_OFFSET
385 default 0xdffffc0000000000
387 config HAVE_INTEL_TXT
389 depends on INTEL_IOMMU && ACPI
393 depends on X86_64 && SMP
395 config ARCH_SUPPORTS_UPROBES
398 config FIX_EARLYCON_MEM
401 config DYNAMIC_PHYSICAL_MASK
404 config PGTABLE_LEVELS
406 default 5 if X86_5LEVEL
411 config CC_HAS_SANE_STACKPROTECTOR
413 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
414 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
416 We have to make sure stack protector is unconditionally disabled if
417 the compiler produces broken code or if it does not let us control
418 the segment on 32-bit kernels.
420 menu "Processor type and features"
423 bool "Symmetric multi-processing support"
425 This enables support for systems with more than one CPU. If you have
426 a system with only one CPU, say N. If you have a system with more
429 If you say N here, the kernel will run on uni- and multiprocessor
430 machines, but will use only one CPU of a multiprocessor machine. If
431 you say Y here, the kernel will run on many, but not all,
432 uniprocessor machines. On a uniprocessor machine, the kernel
433 will run faster if you say N here.
435 Note that if you say Y here and choose architecture "586" or
436 "Pentium" under "Processor family", the kernel will not work on 486
437 architectures. Similarly, multiprocessor kernels for the "PPro"
438 architecture may not work on all Pentium based boards.
440 People using multiprocessor machines who say Y here should also say
441 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
442 Management" code will be disabled if you say Y here.
444 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
445 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
446 <http://www.tldp.org/docs.html#howto>.
448 If you don't know what to do here, say N.
451 bool "Support x2apic"
452 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
454 This enables x2apic support on CPUs that have this feature.
456 This allows 32-bit apic IDs (so it can support very large systems),
457 and accesses the local apic via MSRs not via mmio.
459 Some Intel systems circa 2022 and later are locked into x2APIC mode
460 and can not fall back to the legacy APIC modes if SGX or TDX are
461 enabled in the BIOS. They will boot with very reduced functionality
462 without enabling this option.
464 If you don't know what to do here, say N.
467 bool "Enable MPS table" if ACPI
469 depends on X86_LOCAL_APIC
471 For old smp systems that do not have proper acpi support. Newer systems
472 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
476 depends on X86_GOLDFISH
478 config X86_CPU_RESCTRL
479 bool "x86 CPU resource control support"
480 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
482 select PROC_CPU_RESCTRL if PROC_FS
484 Enable x86 CPU resource control support.
486 Provide support for the allocation and monitoring of system resources
489 Intel calls this Intel Resource Director Technology
490 (Intel(R) RDT). More information about RDT can be found in the
491 Intel x86 Architecture Software Developer Manual.
493 AMD calls this AMD Platform Quality of Service (AMD QoS).
494 More information about AMD QoS can be found in the AMD64 Technology
495 Platform Quality of Service Extensions manual.
500 bool "Flexible Return and Event Delivery"
503 When enabled, try to use Flexible Return and Event Delivery
504 instead of the legacy SYSCALL/SYSENTER/IDT architecture for
505 ring transitions and exception/interrupt handling if the
510 bool "Support for big SMP systems with more than 8 CPUs"
513 This option is needed for the systems that have more than 8 CPUs.
515 config X86_EXTENDED_PLATFORM
516 bool "Support for extended (non-PC) x86 platforms"
519 If you disable this option then the kernel will only support
520 standard PC platforms. (which covers the vast majority of
523 If you enable this option then you'll be able to select support
524 for the following (non-PC) 32 bit x86 platforms:
525 Goldfish (Android emulator)
528 SGI 320/540 (Visual Workstation)
529 STA2X11-based (e.g. Northville)
530 Moorestown MID devices
532 If you have one of these systems, or if you want to build a
533 generic distribution kernel, say Y here - otherwise say N.
537 config X86_EXTENDED_PLATFORM
538 bool "Support for extended (non-PC) x86 platforms"
541 If you disable this option then the kernel will only support
542 standard PC platforms. (which covers the vast majority of
545 If you enable this option then you'll be able to select support
546 for the following (non-PC) 64 bit x86 platforms:
551 If you have one of these systems, or if you want to build a
552 generic distribution kernel, say Y here - otherwise say N.
554 # This is an alphabetically sorted list of 64 bit extended platforms
555 # Please maintain the alphabetic order if and when there are additions
557 bool "Numascale NumaChip"
559 depends on X86_EXTENDED_PLATFORM
562 depends on X86_X2APIC
563 depends on PCI_MMCONFIG
565 Adds support for Numascale NumaChip large-SMP systems. Needed to
566 enable more than ~168 cores.
567 If you don't have one of these, you should say N here.
571 select HYPERVISOR_GUEST
573 depends on X86_64 && PCI
574 depends on X86_EXTENDED_PLATFORM
577 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
578 supposed to run on these EM64T-based machines. Only choose this option
579 if you have one of these machines.
582 bool "SGI Ultraviolet"
584 depends on X86_EXTENDED_PLATFORM
587 depends on KEXEC_CORE
588 depends on X86_X2APIC
591 This option is needed in order to support SGI Ultraviolet systems.
592 If you don't have one of these, you should say N here.
594 # Following is an alphabetically sorted list of 32 bit extended platforms
595 # Please maintain the alphabetic order if and when there are additions
598 bool "Goldfish (Virtual Platform)"
599 depends on X86_EXTENDED_PLATFORM
601 Enable support for the Goldfish virtual platform used primarily
602 for Android development. Unless you are building for the Android
603 Goldfish emulator say N here.
606 bool "CE4100 TV platform"
608 depends on PCI_GODIRECT
609 depends on X86_IO_APIC
611 depends on X86_EXTENDED_PLATFORM
612 select X86_REBOOTFIXUPS
614 select OF_EARLY_FLATTREE
616 Select for the Intel CE media processor (CE4100) SOC.
617 This option compiles in support for the CE4100 SOC for settop
618 boxes and media devices.
621 bool "Intel MID platform support"
622 depends on X86_EXTENDED_PLATFORM
623 depends on X86_PLATFORM_DEVICES
625 depends on X86_64 || (PCI_GOANY && X86_32)
626 depends on X86_IO_APIC
631 Select to build a kernel capable of supporting Intel MID (Mobile
632 Internet Device) platform systems which do not have the PCI legacy
633 interfaces. If you are building for a PC class system say N here.
635 Intel MID platforms are based on an Intel processor and chipset which
636 consume less power than most of the x86 derivatives.
638 config X86_INTEL_QUARK
639 bool "Intel Quark platform support"
641 depends on X86_EXTENDED_PLATFORM
642 depends on X86_PLATFORM_DEVICES
646 depends on X86_IO_APIC
651 Select to include support for Quark X1000 SoC.
652 Say Y here if you have a Quark based system such as the Arduino
653 compatible Intel Galileo.
655 config X86_INTEL_LPSS
656 bool "Intel Low Power Subsystem Support"
657 depends on X86 && ACPI && PCI
662 Select to build support for Intel Low Power Subsystem such as
663 found on Intel Lynxpoint PCH. Selecting this option enables
664 things like clock tree (common clock framework) and pincontrol
665 which are needed by the LPSS peripheral drivers.
667 config X86_AMD_PLATFORM_DEVICE
668 bool "AMD ACPI2Platform devices support"
673 Select to interpret AMD specific ACPI device to platform device
674 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
675 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
676 implemented under PINCTRL subsystem.
679 tristate "Intel SoC IOSF Sideband support for SoC platforms"
682 This option enables sideband register access support for Intel SoC
683 platforms. On these platforms the IOSF sideband is used in lieu of
684 MSR's for some register accesses, mostly but not limited to thermal
685 and power. Drivers may query the availability of this device to
686 determine if they need the sideband in order to work on these
687 platforms. The sideband is available on the following SoC products.
688 This list is not meant to be exclusive.
693 You should say Y if you are running a kernel on one of these SoC's.
695 config IOSF_MBI_DEBUG
696 bool "Enable IOSF sideband access through debugfs"
697 depends on IOSF_MBI && DEBUG_FS
699 Select this option to expose the IOSF sideband access registers (MCR,
700 MDR, MCRX) through debugfs to write and read register information from
701 different units on the SoC. This is most useful for obtaining device
702 state information for debug and analysis. As this is a general access
703 mechanism, users of this option would have specific knowledge of the
704 device they want to access.
706 If you don't require the option or are in doubt, say N.
709 bool "RDC R-321x SoC"
711 depends on X86_EXTENDED_PLATFORM
713 select X86_REBOOTFIXUPS
715 This option is needed for RDC R-321x system-on-chip, also known
717 If you don't have one of these chips, you should say N here.
719 config X86_32_NON_STANDARD
720 bool "Support non-standard 32-bit SMP architectures"
721 depends on X86_32 && SMP
722 depends on X86_EXTENDED_PLATFORM
724 This option compiles in the bigsmp and STA2X11 default
725 subarchitectures. It is intended for a generic binary
726 kernel. If you select them all, kernel will probe it one by
727 one and will fallback to default.
729 # Alphabetically sorted list of Non standard 32 bit platforms
731 config X86_SUPPORTS_MEMORY_FAILURE
733 # MCE code calls memory_failure():
735 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
736 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
737 depends on X86_64 || !SPARSEMEM
738 select ARCH_SUPPORTS_MEMORY_FAILURE
741 bool "STA2X11 Companion Chip Support"
742 depends on X86_32_NON_STANDARD && PCI
747 This adds support for boards based on the STA2X11 IO-Hub,
748 a.k.a. "ConneXt". The chip is used in place of the standard
749 PC chipset, so all "standard" peripherals are missing. If this
750 option is selected the kernel will still be able to boot on
751 standard PC machines.
754 tristate "Eurobraille/Iris poweroff module"
757 The Iris machines from EuroBraille do not have APM or ACPI support
758 to shut themselves down properly. A special I/O sequence is
759 needed to do so, which is what this module does at
762 This is only for Iris machines from EuroBraille.
766 config SCHED_OMIT_FRAME_POINTER
768 prompt "Single-depth WCHAN output"
771 Calculate simpler /proc/<PID>/wchan values. If this option
772 is disabled then wchan values will recurse back to the
773 caller function. This provides more accurate wchan values,
774 at the expense of slightly more scheduling overhead.
776 If in doubt, say "Y".
778 menuconfig HYPERVISOR_GUEST
779 bool "Linux guest support"
781 Say Y here to enable options for running Linux under various hyper-
782 visors. This option enables basic hypervisor detection and platform
785 If you say N, all options in this submenu will be skipped and
786 disabled, and Linux guest support won't be built in.
791 bool "Enable paravirtualization code"
792 depends on HAVE_STATIC_CALL
794 This changes the kernel so it can modify itself when it is run
795 under a hypervisor, potentially improving performance significantly
796 over full virtualization. However, when run without a hypervisor
797 the kernel is theoretically slower and slightly larger.
802 config PARAVIRT_DEBUG
803 bool "paravirt-ops debugging"
804 depends on PARAVIRT && DEBUG_KERNEL
806 Enable to debug paravirt_ops internals. Specifically, BUG if
807 a paravirt_op is missing when it is called.
809 config PARAVIRT_SPINLOCKS
810 bool "Paravirtualization layer for spinlocks"
811 depends on PARAVIRT && SMP
813 Paravirtualized spinlocks allow a pvops backend to replace the
814 spinlock implementation with something virtualization-friendly
815 (for example, block the virtual CPU rather than spinning).
817 It has a minimal impact on native kernels and gives a nice performance
818 benefit on paravirtualized KVM / Xen kernels.
820 If you are unsure how to answer this question, answer Y.
822 config X86_HV_CALLBACK_VECTOR
825 source "arch/x86/xen/Kconfig"
828 bool "KVM Guest support (including kvmclock)"
830 select PARAVIRT_CLOCK
831 select ARCH_CPUIDLE_HALTPOLL
832 select X86_HV_CALLBACK_VECTOR
835 This option enables various optimizations for running under the KVM
836 hypervisor. It includes a paravirtualized clock, so that instead
837 of relying on a PIT (or probably other) emulation by the
838 underlying device model, the host provides the guest with
839 timing infrastructure such as time of day, and system time
841 config ARCH_CPUIDLE_HALTPOLL
843 prompt "Disable host haltpoll when loading haltpoll driver"
845 If virtualized under KVM, disable host haltpoll.
848 bool "Support for running PVH guests"
850 This option enables the PVH entry point for guest virtual machines
851 as specified in the x86/HVM direct boot ABI.
853 config PARAVIRT_TIME_ACCOUNTING
854 bool "Paravirtual steal time accounting"
857 Select this option to enable fine granularity task steal time
858 accounting. Time spent executing other tasks in parallel with
859 the current vCPU is discounted from the vCPU power. To account for
860 that, there can be a small performance impact.
862 If in doubt, say N here.
864 config PARAVIRT_CLOCK
867 config JAILHOUSE_GUEST
868 bool "Jailhouse non-root cell support"
869 depends on X86_64 && PCI
872 This option allows to run Linux as guest in a Jailhouse non-root
873 cell. You can leave this option disabled if you only want to start
874 Jailhouse and run Linux afterwards in the root cell.
877 bool "ACRN Guest support"
879 select X86_HV_CALLBACK_VECTOR
881 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
882 a flexible, lightweight reference open-source hypervisor, built with
883 real-time and safety-criticality in mind. It is built for embedded
884 IOT with small footprint and real-time features. More details can be
885 found in https://projectacrn.org/.
887 config INTEL_TDX_GUEST
888 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
889 depends on X86_64 && CPU_SUP_INTEL
890 depends on X86_X2APIC
892 select ARCH_HAS_CC_PLATFORM
893 select X86_MEM_ENCRYPT
895 select UNACCEPTED_MEMORY
897 Support running as a guest under Intel TDX. Without this support,
898 the guest kernel can not boot or run under TDX.
899 TDX includes memory encryption and integrity capabilities
900 which protect the confidentiality and integrity of guest
901 memory contents and CPU state. TDX guests are protected from
902 some attacks from the VMM.
904 endif # HYPERVISOR_GUEST
906 source "arch/x86/Kconfig.cpu"
910 prompt "HPET Timer Support" if X86_32
912 Use the IA-PC HPET (High Precision Event Timer) to manage
913 time in preference to the PIT and RTC, if a HPET is
915 HPET is the next generation timer replacing legacy 8254s.
916 The HPET provides a stable time base on SMP
917 systems, unlike the TSC, but it is more expensive to access,
918 as it is off-chip. The interface used is documented
919 in the HPET spec, revision 1.
921 You can safely choose Y here. However, HPET will only be
922 activated if the platform and the BIOS support this feature.
923 Otherwise the 8254 will be used for timing services.
925 Choose N to continue using the legacy 8254 timer.
927 config HPET_EMULATE_RTC
929 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
931 # Mark as expert because too many people got it wrong.
932 # The code disables itself when not needed.
935 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
936 bool "Enable DMI scanning" if EXPERT
938 Enabled scanning of DMI to identify machine quirks. Say Y
939 here unless you have verified that your setup is not
940 affected by entries in the DMI blacklist. Required by PNP
944 bool "Old AMD GART IOMMU support"
948 depends on X86_64 && PCI && AMD_NB
950 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
951 GART based hardware IOMMUs.
953 The GART supports full DMA access for devices with 32-bit access
954 limitations, on systems with more than 3 GB. This is usually needed
955 for USB, sound, many IDE/SATA chipsets and some other devices.
957 Newer systems typically have a modern AMD IOMMU, supported via
958 the CONFIG_AMD_IOMMU=y config option.
960 In normal configurations this driver is only active when needed:
961 there's more than 3 GB of memory and the system contains a
962 32-bit limited device.
966 config BOOT_VESA_SUPPORT
969 If true, at least one selected framebuffer driver can take advantage
970 of VESA video modes set at an early boot stage via the vga= parameter.
973 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
974 depends on X86_64 && SMP && DEBUG_KERNEL
975 select CPUMASK_OFFSTACK
977 Enable maximum number of CPUS and NUMA Nodes for this architecture.
981 # The maximum number of CPUs supported:
983 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
984 # and which can be configured interactively in the
985 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
987 # The ranges are different on 32-bit and 64-bit kernels, depending on
988 # hardware capabilities and scalability features of the kernel.
990 # ( If MAXSMP is enabled we just use the highest possible value and disable
991 # interactive configuration. )
994 config NR_CPUS_RANGE_BEGIN
996 default NR_CPUS_RANGE_END if MAXSMP
1000 config NR_CPUS_RANGE_END
1003 default 64 if SMP && X86_BIGSMP
1004 default 8 if SMP && !X86_BIGSMP
1007 config NR_CPUS_RANGE_END
1010 default 8192 if SMP && CPUMASK_OFFSTACK
1011 default 512 if SMP && !CPUMASK_OFFSTACK
1014 config NR_CPUS_DEFAULT
1017 default 32 if X86_BIGSMP
1021 config NR_CPUS_DEFAULT
1024 default 8192 if MAXSMP
1029 int "Maximum number of CPUs" if SMP && !MAXSMP
1030 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1031 default NR_CPUS_DEFAULT
1033 This allows you to specify the maximum number of CPUs which this
1034 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1035 supported value is 8192, otherwise the maximum value is 512. The
1036 minimum value which makes sense is 2.
1038 This is purely to save memory: each supported CPU adds about 8KB
1039 to the kernel image.
1041 config SCHED_CLUSTER
1042 bool "Cluster scheduler support"
1046 Cluster scheduler support improves the CPU scheduler's decision
1047 making when dealing with machines that have clusters of CPUs.
1048 Cluster usually means a couple of CPUs which are placed closely
1049 by sharing mid-level caches, last-level cache tags or internal
1057 prompt "Multi-core scheduler support"
1060 Multi-core scheduler support improves the CPU scheduler's decision
1061 making when dealing with multi-core CPU chips at a cost of slightly
1062 increased overhead in some places. If unsure say N here.
1064 config SCHED_MC_PRIO
1065 bool "CPU core priorities scheduler support"
1066 depends on SCHED_MC && CPU_SUP_INTEL
1067 select X86_INTEL_PSTATE
1071 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1072 core ordering determined at manufacturing time, which allows
1073 certain cores to reach higher turbo frequencies (when running
1074 single threaded workloads) than others.
1076 Enabling this kernel feature teaches the scheduler about
1077 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1078 scheduler's CPU selection logic accordingly, so that higher
1079 overall system performance can be achieved.
1081 This feature will have no effect on CPUs without this feature.
1083 If unsure say Y here.
1087 depends on !SMP && X86_LOCAL_APIC
1090 bool "Local APIC support on uniprocessors" if !PCI_MSI
1092 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1094 A local APIC (Advanced Programmable Interrupt Controller) is an
1095 integrated interrupt controller in the CPU. If you have a single-CPU
1096 system which has a processor with a local APIC, you can say Y here to
1097 enable and use it. If you say Y here even though your machine doesn't
1098 have a local APIC, then the kernel will still run with no slowdown at
1099 all. The local APIC supports CPU-generated self-interrupts (timer,
1100 performance counters), and the NMI watchdog which detects hard
1103 config X86_UP_IOAPIC
1104 bool "IO-APIC support on uniprocessors"
1105 depends on X86_UP_APIC
1107 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1108 SMP-capable replacement for PC-style interrupt controllers. Most
1109 SMP systems and many recent uniprocessor systems have one.
1111 If you have a single-CPU system with an IO-APIC, you can say Y here
1112 to use it. If you say Y here even though your machine doesn't have
1113 an IO-APIC, then the kernel will still run with no slowdown at all.
1115 config X86_LOCAL_APIC
1117 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1118 select IRQ_DOMAIN_HIERARCHY
1122 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1124 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1125 bool "Reroute for broken boot IRQs"
1126 depends on X86_IO_APIC
1128 This option enables a workaround that fixes a source of
1129 spurious interrupts. This is recommended when threaded
1130 interrupt handling is used on systems where the generation of
1131 superfluous "boot interrupts" cannot be disabled.
1133 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1134 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1135 kernel does during interrupt handling). On chipsets where this
1136 boot IRQ generation cannot be disabled, this workaround keeps
1137 the original IRQ line masked so that only the equivalent "boot
1138 IRQ" is delivered to the CPUs. The workaround also tells the
1139 kernel to set up the IRQ handler on the boot IRQ line. In this
1140 way only one interrupt is delivered to the kernel. Otherwise
1141 the spurious second interrupt may cause the kernel to bring
1142 down (vital) interrupt lines.
1144 Only affects "broken" chipsets. Interrupt sharing may be
1145 increased on these systems.
1148 bool "Machine Check / overheating reporting"
1149 select GENERIC_ALLOCATOR
1152 Machine Check support allows the processor to notify the
1153 kernel if it detects a problem (e.g. overheating, data corruption).
1154 The action the kernel takes depends on the severity of the problem,
1155 ranging from warning messages to halting the machine.
1157 config X86_MCELOG_LEGACY
1158 bool "Support for deprecated /dev/mcelog character device"
1161 Enable support for /dev/mcelog which is needed by the old mcelog
1162 userspace logging daemon. Consider switching to the new generation
1165 config X86_MCE_INTEL
1167 prompt "Intel MCE features"
1168 depends on X86_MCE && X86_LOCAL_APIC
1170 Additional support for intel specific MCE features such as
1171 the thermal monitor.
1175 prompt "AMD MCE features"
1176 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1178 Additional support for AMD specific MCE features such as
1179 the DRAM Error Threshold.
1181 config X86_ANCIENT_MCE
1182 bool "Support for old Pentium 5 / WinChip machine checks"
1183 depends on X86_32 && X86_MCE
1185 Include support for machine check handling on old Pentium 5 or WinChip
1186 systems. These typically need to be enabled explicitly on the command
1189 config X86_MCE_THRESHOLD
1190 depends on X86_MCE_AMD || X86_MCE_INTEL
1193 config X86_MCE_INJECT
1194 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1195 tristate "Machine check injector support"
1197 Provide support for injecting machine checks for testing purposes.
1198 If you don't know what a machine check is and you don't do kernel
1199 QA it is safe to say n.
1201 source "arch/x86/events/Kconfig"
1203 config X86_LEGACY_VM86
1204 bool "Legacy VM86 support"
1207 This option allows user programs to put the CPU into V8086
1208 mode, which is an 80286-era approximation of 16-bit real mode.
1210 Some very old versions of X and/or vbetool require this option
1211 for user mode setting. Similarly, DOSEMU will use it if
1212 available to accelerate real mode DOS programs. However, any
1213 recent version of DOSEMU, X, or vbetool should be fully
1214 functional even without kernel VM86 support, as they will all
1215 fall back to software emulation. Nevertheless, if you are using
1216 a 16-bit DOS program where 16-bit performance matters, vm86
1217 mode might be faster than emulation and you might want to
1220 Note that any app that works on a 64-bit kernel is unlikely to
1221 need this option, as 64-bit kernels don't, and can't, support
1222 V8086 mode. This option is also unrelated to 16-bit protected
1223 mode and is not needed to run most 16-bit programs under Wine.
1225 Enabling this option increases the complexity of the kernel
1226 and slows down exception handling a tiny bit.
1228 If unsure, say N here.
1232 default X86_LEGACY_VM86
1235 bool "Enable support for 16-bit segments" if EXPERT
1237 depends on MODIFY_LDT_SYSCALL
1239 This option is required by programs like Wine to run 16-bit
1240 protected mode legacy code on x86 processors. Disabling
1241 this option saves about 300 bytes on i386, or around 6K text
1242 plus 16K runtime memory on x86-64,
1246 depends on X86_16BIT && X86_32
1250 depends on X86_16BIT && X86_64
1252 config X86_VSYSCALL_EMULATION
1253 bool "Enable vsyscall emulation" if EXPERT
1257 This enables emulation of the legacy vsyscall page. Disabling
1258 it is roughly equivalent to booting with vsyscall=none, except
1259 that it will also disable the helpful warning if a program
1260 tries to use a vsyscall. With this option set to N, offending
1261 programs will just segfault, citing addresses of the form
1264 This option is required by many programs built before 2013, and
1265 care should be used even with newer programs if set to N.
1267 Disabling this option saves about 7K of kernel size and
1268 possibly 4K of additional runtime pagetable memory.
1270 config X86_IOPL_IOPERM
1271 bool "IOPERM and IOPL Emulation"
1274 This enables the ioperm() and iopl() syscalls which are necessary
1275 for legacy applications.
1277 Legacy IOPL support is an overbroad mechanism which allows user
1278 space aside of accessing all 65536 I/O ports also to disable
1279 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1280 capabilities and permission from potentially active security
1283 The emulation restricts the functionality of the syscall to
1284 only allowing the full range I/O port access, but prevents the
1285 ability to disable interrupts from user space which would be
1286 granted if the hardware IOPL mechanism would be used.
1289 tristate "Toshiba Laptop support"
1292 This adds a driver to safely access the System Management Mode of
1293 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1294 not work on models with a Phoenix BIOS. The System Management Mode
1295 is used to set the BIOS and power saving options on Toshiba portables.
1297 For information on utilities to make use of this driver see the
1298 Toshiba Linux utilities web site at:
1299 <http://www.buzzard.org.uk/toshiba/>.
1301 Say Y if you intend to run this kernel on a Toshiba portable.
1304 config X86_REBOOTFIXUPS
1305 bool "Enable X86 board specific fixups for reboot"
1308 This enables chipset and/or board specific fixups to be done
1309 in order to get reboot to work correctly. This is only needed on
1310 some combinations of hardware and BIOS. The symptom, for which
1311 this config is intended, is when reboot ends with a stalled/hung
1314 Currently, the only fixup is for the Geode machines using
1315 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1317 Say Y if you want to enable the fixup. Currently, it's safe to
1318 enable this option even if you don't need it.
1323 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1325 config MICROCODE_INITRD32
1327 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1329 config MICROCODE_LATE_LOADING
1330 bool "Late microcode loading (DANGEROUS)"
1332 depends on MICROCODE && SMP
1334 Loading microcode late, when the system is up and executing instructions
1335 is a tricky business and should be avoided if possible. Just the sequence
1336 of synchronizing all cores and SMT threads is one fragile dance which does
1337 not guarantee that cores might not softlock after the loading. Therefore,
1338 use this at your own risk. Late loading taints the kernel unless the
1339 microcode header indicates that it is safe for late loading via the
1340 minimal revision check. This minimal revision check can be enforced on
1341 the kernel command line with "microcode.minrev=Y".
1343 config MICROCODE_LATE_FORCE_MINREV
1344 bool "Enforce late microcode loading minimal revision check"
1346 depends on MICROCODE_LATE_LOADING
1348 To prevent that users load microcode late which modifies already
1349 in use features, newer microcode patches have a minimum revision field
1350 in the microcode header, which tells the kernel which minimum
1351 revision must be active in the CPU to safely load that new microcode
1352 late into the running system. If disabled the check will not
1353 be enforced but the kernel will be tainted when the minimal
1354 revision check fails.
1356 This minimal revision check can also be controlled via the
1357 "microcode.minrev" parameter on the kernel command line.
1362 tristate "/dev/cpu/*/msr - Model-specific register support"
1364 This device gives privileged processes access to the x86
1365 Model-Specific Registers (MSRs). It is a character device with
1366 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1367 MSR accesses are directed to a specific CPU on multi-processor
1371 tristate "/dev/cpu/*/cpuid - CPU information support"
1373 This device gives processes access to the x86 CPUID instruction to
1374 be executed on a specific processor. It is a character device
1375 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1379 prompt "High Memory Support"
1386 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1387 However, the address space of 32-bit x86 processors is only 4
1388 Gigabytes large. That means that, if you have a large amount of
1389 physical memory, not all of it can be "permanently mapped" by the
1390 kernel. The physical memory that's not permanently mapped is called
1393 If you are compiling a kernel which will never run on a machine with
1394 more than 1 Gigabyte total physical RAM, answer "off" here (default
1395 choice and suitable for most users). This will result in a "3GB/1GB"
1396 split: 3GB are mapped so that each process sees a 3GB virtual memory
1397 space and the remaining part of the 4GB virtual memory space is used
1398 by the kernel to permanently map as much physical memory as
1401 If the machine has between 1 and 4 Gigabytes physical RAM, then
1404 If more than 4 Gigabytes is used then answer "64GB" here. This
1405 selection turns Intel PAE (Physical Address Extension) mode on.
1406 PAE implements 3-level paging on IA32 processors. PAE is fully
1407 supported by Linux, PAE mode is implemented on all recent Intel
1408 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1409 then the kernel will not boot on CPUs that don't support PAE!
1411 The actual amount of total physical memory will either be
1412 auto detected or can be forced by using a kernel command line option
1413 such as "mem=256M". (Try "man bootparam" or see the documentation of
1414 your boot loader (lilo or loadlin) about how to pass options to the
1415 kernel at boot time.)
1417 If unsure, say "off".
1422 Select this if you have a 32-bit processor and between 1 and 4
1423 gigabytes of physical RAM.
1427 depends on X86_HAVE_PAE
1430 Select this if you have a 32-bit processor and more than 4
1431 gigabytes of physical RAM.
1436 prompt "Memory split" if EXPERT
1440 Select the desired split between kernel and user memory.
1442 If the address range available to the kernel is less than the
1443 physical memory installed, the remaining memory will be available
1444 as "high memory". Accessing high memory is a little more costly
1445 than low memory, as it needs to be mapped into the kernel first.
1446 Note that increasing the kernel address space limits the range
1447 available to user programs, making the address space there
1448 tighter. Selecting anything other than the default 3G/1G split
1449 will also likely make your kernel incompatible with binary-only
1452 If you are not absolutely sure what you are doing, leave this
1456 bool "3G/1G user/kernel split"
1457 config VMSPLIT_3G_OPT
1459 bool "3G/1G user/kernel split (for full 1G low memory)"
1461 bool "2G/2G user/kernel split"
1462 config VMSPLIT_2G_OPT
1464 bool "2G/2G user/kernel split (for full 2G low memory)"
1466 bool "1G/3G user/kernel split"
1471 default 0xB0000000 if VMSPLIT_3G_OPT
1472 default 0x80000000 if VMSPLIT_2G
1473 default 0x78000000 if VMSPLIT_2G_OPT
1474 default 0x40000000 if VMSPLIT_1G
1480 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1483 bool "PAE (Physical Address Extension) Support"
1484 depends on X86_32 && X86_HAVE_PAE
1485 select PHYS_ADDR_T_64BIT
1488 PAE is required for NX support, and furthermore enables
1489 larger swapspace support for non-overcommit purposes. It
1490 has the cost of more pagetable lookup overhead, and also
1491 consumes more pagetable space per process.
1494 bool "Enable 5-level page tables support"
1496 select DYNAMIC_MEMORY_LAYOUT
1497 select SPARSEMEM_VMEMMAP
1500 5-level paging enables access to larger address space:
1501 up to 128 PiB of virtual address space and 4 PiB of
1502 physical address space.
1504 It will be supported by future Intel CPUs.
1506 A kernel with the option enabled can be booted on machines that
1507 support 4- or 5-level paging.
1509 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1514 config X86_DIRECT_GBPAGES
1518 Certain kernel features effectively disable kernel
1519 linear 1 GB mappings (even if the CPU otherwise
1520 supports them), so don't confuse the user by printing
1521 that we have them enabled.
1523 config X86_CPA_STATISTICS
1524 bool "Enable statistic for Change Page Attribute"
1527 Expose statistics about the Change Page Attribute mechanism, which
1528 helps to determine the effectiveness of preserving large and huge
1529 page mappings when mapping protections are changed.
1531 config X86_MEM_ENCRYPT
1532 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1533 select DYNAMIC_PHYSICAL_MASK
1536 config AMD_MEM_ENCRYPT
1537 bool "AMD Secure Memory Encryption (SME) support"
1538 depends on X86_64 && CPU_SUP_AMD
1540 select DMA_COHERENT_POOL
1541 select ARCH_USE_MEMREMAP_PROT
1542 select INSTRUCTION_DECODER
1543 select ARCH_HAS_CC_PLATFORM
1544 select X86_MEM_ENCRYPT
1545 select UNACCEPTED_MEMORY
1547 Say yes to enable support for the encryption of system memory.
1548 This requires an AMD processor that supports Secure Memory
1551 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1552 bool "Activate AMD Secure Memory Encryption (SME) by default"
1553 depends on AMD_MEM_ENCRYPT
1555 Say yes to have system memory encrypted by default if running on
1556 an AMD processor that supports Secure Memory Encryption (SME).
1558 If set to Y, then the encryption of system memory can be
1559 deactivated with the mem_encrypt=off command line option.
1561 If set to N, then the encryption of system memory can be
1562 activated with the mem_encrypt=on command line option.
1564 # Common NUMA Features
1566 bool "NUMA Memory Allocation and Scheduler Support"
1568 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1569 default y if X86_BIGSMP
1570 select USE_PERCPU_NUMA_NODE_ID
1571 select OF_NUMA if OF
1573 Enable NUMA (Non-Uniform Memory Access) support.
1575 The kernel will try to allocate memory used by a CPU on the
1576 local memory controller of the CPU and add some more
1577 NUMA awareness to the kernel.
1579 For 64-bit this is recommended if the system is Intel Core i7
1580 (or later), AMD Opteron, or EM64T NUMA.
1582 For 32-bit this is only needed if you boot a 32-bit
1583 kernel on a 64-bit NUMA platform.
1585 Otherwise, you should say N.
1589 prompt "Old style AMD Opteron NUMA detection"
1590 depends on X86_64 && NUMA && PCI
1592 Enable AMD NUMA node topology detection. You should say Y here if
1593 you have a multi processor AMD system. This uses an old method to
1594 read the NUMA configuration directly from the builtin Northbridge
1595 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1596 which also takes priority if both are compiled in.
1598 config X86_64_ACPI_NUMA
1600 prompt "ACPI NUMA detection"
1601 depends on X86_64 && NUMA && ACPI && PCI
1604 Enable ACPI SRAT based node topology detection.
1607 bool "NUMA emulation"
1610 Enable NUMA emulation. A flat machine will be split
1611 into virtual nodes when booted with "numa=fake=N", where N is the
1612 number of nodes. This is only useful for debugging.
1615 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1617 default "10" if MAXSMP
1618 default "6" if X86_64
1622 Specify the maximum number of NUMA Nodes available on the target
1623 system. Increases memory reserved to accommodate various tables.
1625 config ARCH_FLATMEM_ENABLE
1627 depends on X86_32 && !NUMA
1629 config ARCH_SPARSEMEM_ENABLE
1631 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1632 select SPARSEMEM_STATIC if X86_32
1633 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1635 config ARCH_SPARSEMEM_DEFAULT
1636 def_bool X86_64 || (NUMA && X86_32)
1638 config ARCH_SELECT_MEMORY_MODEL
1640 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1642 config ARCH_MEMORY_PROBE
1643 bool "Enable sysfs memory/probe interface"
1644 depends on MEMORY_HOTPLUG
1646 This option enables a sysfs memory/probe interface for testing.
1647 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1648 If you are unsure how to answer this question, answer N.
1650 config ARCH_PROC_KCORE_TEXT
1652 depends on X86_64 && PROC_KCORE
1654 config ILLEGAL_POINTER_VALUE
1657 default 0xdead000000000000 if X86_64
1659 config X86_PMEM_LEGACY_DEVICE
1662 config X86_PMEM_LEGACY
1663 tristate "Support non-standard NVDIMMs and ADR protected memory"
1664 depends on PHYS_ADDR_T_64BIT
1666 select X86_PMEM_LEGACY_DEVICE
1667 select NUMA_KEEP_MEMINFO if NUMA
1670 Treat memory marked using the non-standard e820 type of 12 as used
1671 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1672 The kernel will offer these regions to the 'pmem' driver so
1673 they can be used for persistent storage.
1678 bool "Allocate 3rd-level pagetables from highmem"
1681 The VM uses one page table entry for each page of physical memory.
1682 For systems with a lot of RAM, this can be wasteful of precious
1683 low memory. Setting this option will put user-space page table
1684 entries in high memory.
1686 config X86_CHECK_BIOS_CORRUPTION
1687 bool "Check for low memory corruption"
1689 Periodically check for memory corruption in low memory, which
1690 is suspected to be caused by BIOS. Even when enabled in the
1691 configuration, it is disabled at runtime. Enable it by
1692 setting "memory_corruption_check=1" on the kernel command
1693 line. By default it scans the low 64k of memory every 60
1694 seconds; see the memory_corruption_check_size and
1695 memory_corruption_check_period parameters in
1696 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1698 When enabled with the default parameters, this option has
1699 almost no overhead, as it reserves a relatively small amount
1700 of memory and scans it infrequently. It both detects corruption
1701 and prevents it from affecting the running system.
1703 It is, however, intended as a diagnostic tool; if repeatable
1704 BIOS-originated corruption always affects the same memory,
1705 you can use memmap= to prevent the kernel from using that
1708 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1709 bool "Set the default setting of memory_corruption_check"
1710 depends on X86_CHECK_BIOS_CORRUPTION
1713 Set whether the default state of memory_corruption_check is
1716 config MATH_EMULATION
1718 depends on MODIFY_LDT_SYSCALL
1719 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1721 Linux can emulate a math coprocessor (used for floating point
1722 operations) if you don't have one. 486DX and Pentium processors have
1723 a math coprocessor built in, 486SX and 386 do not, unless you added
1724 a 487DX or 387, respectively. (The messages during boot time can
1725 give you some hints here ["man dmesg"].) Everyone needs either a
1726 coprocessor or this emulation.
1728 If you don't have a math coprocessor, you need to say Y here; if you
1729 say Y here even though you have a coprocessor, the coprocessor will
1730 be used nevertheless. (This behavior can be changed with the kernel
1731 command line option "no387", which comes handy if your coprocessor
1732 is broken. Try "man bootparam" or see the documentation of your boot
1733 loader (lilo or loadlin) about how to pass options to the kernel at
1734 boot time.) This means that it is a good idea to say Y here if you
1735 intend to use this kernel on different machines.
1737 More information about the internals of the Linux math coprocessor
1738 emulation can be found in <file:arch/x86/math-emu/README>.
1740 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1741 kernel, it won't hurt.
1745 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1747 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1748 the Memory Type Range Registers (MTRRs) may be used to control
1749 processor access to memory ranges. This is most useful if you have
1750 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1751 allows bus write transfers to be combined into a larger transfer
1752 before bursting over the PCI/AGP bus. This can increase performance
1753 of image write operations 2.5 times or more. Saying Y here creates a
1754 /proc/mtrr file which may be used to manipulate your processor's
1755 MTRRs. Typically the X server should use this.
1757 This code has a reasonably generic interface so that similar
1758 control registers on other processors can be easily supported
1761 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1762 Registers (ARRs) which provide a similar functionality to MTRRs. For
1763 these, the ARRs are used to emulate the MTRRs.
1764 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1765 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1766 write-combining. All of these processors are supported by this code
1767 and it makes sense to say Y here if you have one of them.
1769 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1770 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1771 can lead to all sorts of problems, so it's good to say Y here.
1773 You can safely say Y even if your machine doesn't have MTRRs, you'll
1774 just add about 9 KB to your kernel.
1776 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1778 config MTRR_SANITIZER
1780 prompt "MTRR cleanup support"
1783 Convert MTRR layout from continuous to discrete, so X drivers can
1784 add writeback entries.
1786 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1787 The largest mtrr entry size for a continuous block can be set with
1792 config MTRR_SANITIZER_ENABLE_DEFAULT
1793 int "MTRR cleanup enable value (0-1)"
1796 depends on MTRR_SANITIZER
1798 Enable mtrr cleanup default value
1800 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1801 int "MTRR cleanup spare reg num (0-7)"
1804 depends on MTRR_SANITIZER
1806 mtrr cleanup spare entries default, it can be changed via
1807 mtrr_spare_reg_nr=N on the kernel command line.
1811 prompt "x86 PAT support" if EXPERT
1814 Use PAT attributes to setup page level cache control.
1816 PATs are the modern equivalents of MTRRs and are much more
1817 flexible than MTRRs.
1819 Say N here if you see bootup problems (boot crash, boot hang,
1820 spontaneous reboots) or a non-working video driver.
1824 config ARCH_USES_PG_UNCACHED
1830 prompt "User Mode Instruction Prevention" if EXPERT
1832 User Mode Instruction Prevention (UMIP) is a security feature in
1833 some x86 processors. If enabled, a general protection fault is
1834 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1835 executed in user mode. These instructions unnecessarily expose
1836 information about the hardware state.
1838 The vast majority of applications do not use these instructions.
1839 For the very few that do, software emulation is provided in
1840 specific cases in protected and virtual-8086 modes. Emulated
1844 # GCC >= 9 and binutils >= 2.29
1845 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1847 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1848 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1849 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1850 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1856 CET features configured (Shadow stack or IBT)
1858 config X86_KERNEL_IBT
1859 prompt "Indirect Branch Tracking"
1861 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1862 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1863 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1867 Build the kernel with support for Indirect Branch Tracking, a
1868 hardware support course-grain forward-edge Control Flow Integrity
1869 protection. It enforces that all indirect calls must land on
1870 an ENDBR instruction, as such, the compiler will instrument the
1871 code with them to make this happen.
1873 In addition to building the kernel with IBT, seal all functions that
1874 are not indirect call targets, avoiding them ever becoming one.
1876 This requires LTO like objtool runs and will slow down the build. It
1877 does significantly reduce the number of ENDBR instructions in the
1880 config X86_INTEL_MEMORY_PROTECTION_KEYS
1881 prompt "Memory Protection Keys"
1883 # Note: only available in 64-bit mode
1884 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1885 select ARCH_USES_HIGH_VMA_FLAGS
1886 select ARCH_HAS_PKEYS
1888 Memory Protection Keys provides a mechanism for enforcing
1889 page-based protections, but without requiring modification of the
1890 page tables when an application changes protection domains.
1892 For details, see Documentation/core-api/protection-keys.rst
1897 prompt "TSX enable mode"
1898 depends on CPU_SUP_INTEL
1899 default X86_INTEL_TSX_MODE_OFF
1901 Intel's TSX (Transactional Synchronization Extensions) feature
1902 allows to optimize locking protocols through lock elision which
1903 can lead to a noticeable performance boost.
1905 On the other hand it has been shown that TSX can be exploited
1906 to form side channel attacks (e.g. TAA) and chances are there
1907 will be more of those attacks discovered in the future.
1909 Therefore TSX is not enabled by default (aka tsx=off). An admin
1910 might override this decision by tsx=on the command line parameter.
1911 Even with TSX enabled, the kernel will attempt to enable the best
1912 possible TAA mitigation setting depending on the microcode available
1913 for the particular machine.
1915 This option allows to set the default tsx mode between tsx=on, =off
1916 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1919 Say off if not sure, auto if TSX is in use but it should be used on safe
1920 platforms or on if TSX is in use and the security aspect of tsx is not
1923 config X86_INTEL_TSX_MODE_OFF
1926 TSX is disabled if possible - equals to tsx=off command line parameter.
1928 config X86_INTEL_TSX_MODE_ON
1931 TSX is always enabled on TSX capable HW - equals the tsx=on command
1934 config X86_INTEL_TSX_MODE_AUTO
1937 TSX is enabled on TSX capable HW that is believed to be safe against
1938 side channel attacks- equals the tsx=auto command line parameter.
1942 bool "Software Guard eXtensions (SGX)"
1943 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1945 depends on CRYPTO_SHA256=y
1947 select NUMA_KEEP_MEMINFO if NUMA
1950 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1951 that can be used by applications to set aside private regions of code
1952 and data, referred to as enclaves. An enclave's private memory can
1953 only be accessed by code running within the enclave. Accesses from
1954 outside the enclave, including other enclaves, are disallowed by
1959 config X86_USER_SHADOW_STACK
1960 bool "X86 userspace shadow stack"
1963 select ARCH_USES_HIGH_VMA_FLAGS
1966 Shadow stack protection is a hardware feature that detects function
1967 return address corruption. This helps mitigate ROP attacks.
1968 Applications must be enabled to use it, and old userspace does not
1969 get protection "for free".
1971 CPUs supporting shadow stacks were first released in 2020.
1973 See Documentation/arch/x86/shstk.rst for more information.
1977 config INTEL_TDX_HOST
1978 bool "Intel Trust Domain Extensions (TDX) host support"
1979 depends on CPU_SUP_INTEL
1981 depends on KVM_INTEL
1982 depends on X86_X2APIC
1983 select ARCH_KEEP_MEMBLOCK
1984 depends on CONTIG_ALLOC
1985 depends on !KEXEC_CORE
1988 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1989 host and certain physical attacks. This option enables necessary TDX
1990 support in the host kernel to run confidential VMs.
1995 bool "EFI runtime service support"
1998 select EFI_RUNTIME_WRAPPERS
1999 select ARCH_USE_MEMREMAP_PROT
2000 select EFI_RUNTIME_MAP if KEXEC_CORE
2002 This enables the kernel to use EFI runtime services that are
2003 available (such as the EFI variable services).
2005 This option is only useful on systems that have EFI firmware.
2006 In addition, you should use the latest ELILO loader available
2007 at <http://elilo.sourceforge.net> in order to take advantage
2008 of EFI runtime services. However, even with this option, the
2009 resultant kernel should continue to boot on existing non-EFI
2013 bool "EFI stub support"
2017 This kernel feature allows a bzImage to be loaded directly
2018 by EFI firmware without the use of a bootloader.
2020 See Documentation/admin-guide/efi-stub.rst for more information.
2022 config EFI_HANDOVER_PROTOCOL
2023 bool "EFI handover protocol (DEPRECATED)"
2027 Select this in order to include support for the deprecated EFI
2028 handover protocol, which defines alternative entry points into the
2029 EFI stub. This is a practice that has no basis in the UEFI
2030 specification, and requires a priori knowledge on the part of the
2031 bootloader about Linux/x86 specific ways of passing the command line
2032 and initrd, and where in memory those assets may be loaded.
2034 If in doubt, say Y. Even though the corresponding support is not
2035 present in upstream GRUB or other bootloaders, most distros build
2036 GRUB with numerous downstream patches applied, and may rely on the
2037 handover protocol as as result.
2040 bool "EFI mixed-mode support"
2041 depends on EFI_STUB && X86_64
2043 Enabling this feature allows a 64-bit kernel to be booted
2044 on a 32-bit firmware, provided that your CPU supports 64-bit
2047 Note that it is not possible to boot a mixed-mode enabled
2048 kernel via the EFI boot stub - a bootloader that supports
2049 the EFI handover protocol must be used.
2053 config EFI_FAKE_MEMMAP
2054 bool "Enable EFI fake memory map"
2057 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2058 this parameter, you can add arbitrary attribute to specific memory
2059 range by updating original (firmware provided) EFI memmap. This is
2060 useful for debugging of EFI memmap related feature, e.g., Address
2061 Range Mirroring feature.
2063 config EFI_MAX_FAKE_MEM
2064 int "maximum allowable number of ranges in efi_fake_mem boot option"
2065 depends on EFI_FAKE_MEMMAP
2069 Maximum allowable number of ranges in efi_fake_mem boot option.
2070 Ranges can be set up to this value using comma-separated list.
2071 The default value is 8.
2073 config EFI_RUNTIME_MAP
2074 bool "Export EFI runtime maps to sysfs" if EXPERT
2077 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2078 That memory map is required by the 2nd kernel to set up EFI virtual
2079 mappings after kexec, but can also be used for debugging purposes.
2081 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2083 source "kernel/Kconfig.hz"
2085 config ARCH_SUPPORTS_KEXEC
2088 config ARCH_SUPPORTS_KEXEC_FILE
2091 config ARCH_SELECTS_KEXEC_FILE
2093 depends on KEXEC_FILE
2094 select HAVE_IMA_KEXEC if IMA
2096 config ARCH_SUPPORTS_KEXEC_PURGATORY
2099 config ARCH_SUPPORTS_KEXEC_SIG
2102 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2105 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2108 config ARCH_SUPPORTS_KEXEC_JUMP
2111 config ARCH_SUPPORTS_CRASH_DUMP
2112 def_bool X86_64 || (X86_32 && HIGHMEM)
2114 config ARCH_SUPPORTS_CRASH_HOTPLUG
2117 config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2120 config PHYSICAL_START
2121 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2124 This gives the physical address where the kernel is loaded.
2126 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2127 bzImage will decompress itself to above physical address and
2128 run from there. Otherwise, bzImage will run from the address where
2129 it has been loaded by the boot loader and will ignore above physical
2132 In normal kdump cases one does not have to set/change this option
2133 as now bzImage can be compiled as a completely relocatable image
2134 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2135 address. This option is mainly useful for the folks who don't want
2136 to use a bzImage for capturing the crash dump and want to use a
2137 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2138 to be specifically compiled to run from a specific memory area
2139 (normally a reserved region) and this option comes handy.
2141 So if you are using bzImage for capturing the crash dump,
2142 leave the value here unchanged to 0x1000000 and set
2143 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2144 for capturing the crash dump change this value to start of
2145 the reserved region. In other words, it can be set based on
2146 the "X" value as specified in the "crashkernel=YM@XM"
2147 command line boot parameter passed to the panic-ed
2148 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2149 for more details about crash dumps.
2151 Usage of bzImage for capturing the crash dump is recommended as
2152 one does not have to build two kernels. Same kernel can be used
2153 as production kernel and capture kernel. Above option should have
2154 gone away after relocatable bzImage support is introduced. But it
2155 is present because there are users out there who continue to use
2156 vmlinux for dump capture. This option should go away down the
2159 Don't change this unless you know what you are doing.
2162 bool "Build a relocatable kernel"
2165 This builds a kernel image that retains relocation information
2166 so it can be loaded someplace besides the default 1MB.
2167 The relocations tend to make the kernel binary about 10% larger,
2168 but are discarded at runtime.
2170 One use is for the kexec on panic case where the recovery kernel
2171 must live at a different physical address than the primary
2174 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2175 it has been loaded at and the compile time physical address
2176 (CONFIG_PHYSICAL_START) is used as the minimum location.
2178 config RANDOMIZE_BASE
2179 bool "Randomize the address of the kernel image (KASLR)"
2180 depends on RELOCATABLE
2183 In support of Kernel Address Space Layout Randomization (KASLR),
2184 this randomizes the physical address at which the kernel image
2185 is decompressed and the virtual address where the kernel
2186 image is mapped, as a security feature that deters exploit
2187 attempts relying on knowledge of the location of kernel
2190 On 64-bit, the kernel physical and virtual addresses are
2191 randomized separately. The physical address will be anywhere
2192 between 16MB and the top of physical memory (up to 64TB). The
2193 virtual address will be randomized from 16MB up to 1GB (9 bits
2194 of entropy). Note that this also reduces the memory space
2195 available to kernel modules from 1.5GB to 1GB.
2197 On 32-bit, the kernel physical and virtual addresses are
2198 randomized together. They will be randomized from 16MB up to
2199 512MB (8 bits of entropy).
2201 Entropy is generated using the RDRAND instruction if it is
2202 supported. If RDTSC is supported, its value is mixed into
2203 the entropy pool as well. If neither RDRAND nor RDTSC are
2204 supported, then entropy is read from the i8254 timer. The
2205 usable entropy is limited by the kernel being built using
2206 2GB addressing, and that PHYSICAL_ALIGN must be at a
2207 minimum of 2MB. As a result, only 10 bits of entropy are
2208 theoretically possible, but the implementations are further
2209 limited due to memory layouts.
2213 # Relocation on x86 needs some additional build support
2214 config X86_NEED_RELOCS
2216 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2218 config PHYSICAL_ALIGN
2219 hex "Alignment value to which kernel should be aligned"
2221 range 0x2000 0x1000000 if X86_32
2222 range 0x200000 0x1000000 if X86_64
2224 This value puts the alignment restrictions on physical address
2225 where kernel is loaded and run from. Kernel is compiled for an
2226 address which meets above alignment restriction.
2228 If bootloader loads the kernel at a non-aligned address and
2229 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2230 address aligned to above value and run from there.
2232 If bootloader loads the kernel at a non-aligned address and
2233 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2234 load address and decompress itself to the address it has been
2235 compiled for and run from there. The address for which kernel is
2236 compiled already meets above alignment restrictions. Hence the
2237 end result is that kernel runs from a physical address meeting
2238 above alignment restrictions.
2240 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2241 this value must be a multiple of 0x200000.
2243 Don't change this unless you know what you are doing.
2245 config DYNAMIC_MEMORY_LAYOUT
2248 This option makes base addresses of vmalloc and vmemmap as well as
2249 __PAGE_OFFSET movable during boot.
2251 config RANDOMIZE_MEMORY
2252 bool "Randomize the kernel memory sections"
2254 depends on RANDOMIZE_BASE
2255 select DYNAMIC_MEMORY_LAYOUT
2256 default RANDOMIZE_BASE
2258 Randomizes the base virtual address of kernel memory sections
2259 (physical memory mapping, vmalloc & vmemmap). This security feature
2260 makes exploits relying on predictable memory locations less reliable.
2262 The order of allocations remains unchanged. Entropy is generated in
2263 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2264 configuration have in average 30,000 different possible virtual
2265 addresses for each memory section.
2269 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2270 hex "Physical memory mapping padding" if EXPERT
2271 depends on RANDOMIZE_MEMORY
2272 default "0xa" if MEMORY_HOTPLUG
2274 range 0x1 0x40 if MEMORY_HOTPLUG
2277 Define the padding in terabytes added to the existing physical
2278 memory size during kernel memory randomization. It is useful
2279 for memory hotplug support but reduces the entropy available for
2280 address randomization.
2282 If unsure, leave at the default value.
2284 config ADDRESS_MASKING
2285 bool "Linear Address Masking support"
2288 Linear Address Masking (LAM) modifies the checking that is applied
2289 to 64-bit linear addresses, allowing software to use of the
2290 untranslated address bits for metadata.
2292 The capability can be used for efficient address sanitizers (ASAN)
2293 implementation and for optimizations in JITs.
2301 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2302 depends on COMPAT_32
2304 Certain buggy versions of glibc will crash if they are
2305 presented with a 32-bit vDSO that is not mapped at the address
2306 indicated in its segment table.
2308 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2309 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2310 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2311 the only released version with the bug, but OpenSUSE 9
2312 contains a buggy "glibc 2.3.2".
2314 The symptom of the bug is that everything crashes on startup, saying:
2315 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2317 Saying Y here changes the default value of the vdso32 boot
2318 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2319 This works around the glibc bug but hurts performance.
2321 If unsure, say N: if you are compiling your own kernel, you
2322 are unlikely to be using a buggy version of glibc.
2325 prompt "vsyscall table for legacy applications"
2327 default LEGACY_VSYSCALL_XONLY
2329 Legacy user code that does not know how to find the vDSO expects
2330 to be able to issue three syscalls by calling fixed addresses in
2331 kernel space. Since this location is not randomized with ASLR,
2332 it can be used to assist security vulnerability exploitation.
2334 This setting can be changed at boot time via the kernel command
2335 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2336 is deprecated and can only be enabled using the kernel command
2339 On a system with recent enough glibc (2.14 or newer) and no
2340 static binaries, you can say None without a performance penalty
2341 to improve security.
2343 If unsure, select "Emulate execution only".
2345 config LEGACY_VSYSCALL_XONLY
2346 bool "Emulate execution only"
2348 The kernel traps and emulates calls into the fixed vsyscall
2349 address mapping and does not allow reads. This
2350 configuration is recommended when userspace might use the
2351 legacy vsyscall area but support for legacy binary
2352 instrumentation of legacy code is not needed. It mitigates
2353 certain uses of the vsyscall area as an ASLR-bypassing
2356 config LEGACY_VSYSCALL_NONE
2359 There will be no vsyscall mapping at all. This will
2360 eliminate any risk of ASLR bypass due to the vsyscall
2361 fixed address mapping. Attempts to use the vsyscalls
2362 will be reported to dmesg, so that either old or
2363 malicious userspace programs can be identified.
2368 bool "Built-in kernel command line"
2370 Allow for specifying boot arguments to the kernel at
2371 build time. On some systems (e.g. embedded ones), it is
2372 necessary or convenient to provide some or all of the
2373 kernel boot arguments with the kernel itself (that is,
2374 to not rely on the boot loader to provide them.)
2376 To compile command line arguments into the kernel,
2377 set this option to 'Y', then fill in the
2378 boot arguments in CONFIG_CMDLINE.
2380 Systems with fully functional boot loaders (i.e. non-embedded)
2381 should leave this option set to 'N'.
2384 string "Built-in kernel command string"
2385 depends on CMDLINE_BOOL
2388 Enter arguments here that should be compiled into the kernel
2389 image and used at boot time. If the boot loader provides a
2390 command line at boot time, it is appended to this string to
2391 form the full kernel command line, when the system boots.
2393 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2394 change this behavior.
2396 In most cases, the command line (whether built-in or provided
2397 by the boot loader) should specify the device for the root
2400 config CMDLINE_OVERRIDE
2401 bool "Built-in command line overrides boot loader arguments"
2402 depends on CMDLINE_BOOL && CMDLINE != ""
2404 Set this option to 'Y' to have the kernel ignore the boot loader
2405 command line, and use ONLY the built-in command line.
2407 This is used to work around broken boot loaders. This should
2408 be set to 'N' under normal conditions.
2410 config MODIFY_LDT_SYSCALL
2411 bool "Enable the LDT (local descriptor table)" if EXPERT
2414 Linux can allow user programs to install a per-process x86
2415 Local Descriptor Table (LDT) using the modify_ldt(2) system
2416 call. This is required to run 16-bit or segmented code such as
2417 DOSEMU or some Wine programs. It is also used by some very old
2418 threading libraries.
2420 Enabling this feature adds a small amount of overhead to
2421 context switches and increases the low-level kernel attack
2422 surface. Disabling it removes the modify_ldt(2) system call.
2424 Saying 'N' here may make sense for embedded or server kernels.
2426 config STRICT_SIGALTSTACK_SIZE
2427 bool "Enforce strict size checking for sigaltstack"
2428 depends on DYNAMIC_SIGFRAME
2430 For historical reasons MINSIGSTKSZ is a constant which became
2431 already too small with AVX512 support. Add a mechanism to
2432 enforce strict checking of the sigaltstack size against the
2433 real size of the FPU frame. This option enables the check
2434 by default. It can also be controlled via the kernel command
2435 line option 'strict_sas_size' independent of this config
2436 switch. Enabling it might break existing applications which
2437 allocate a too small sigaltstack but 'work' because they
2438 never get a signal delivered.
2440 Say 'N' unless you want to really enforce this check.
2442 source "kernel/livepatch/Kconfig"
2447 def_bool $(cc-option,-mharden-sls=all)
2449 config CC_HAS_RETURN_THUNK
2450 def_bool $(cc-option,-mfunction-return=thunk-extern)
2452 config CC_HAS_ENTRY_PADDING
2453 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2455 config FUNCTION_PADDING_CFI
2457 default 59 if FUNCTION_ALIGNMENT_64B
2458 default 27 if FUNCTION_ALIGNMENT_32B
2459 default 11 if FUNCTION_ALIGNMENT_16B
2460 default 3 if FUNCTION_ALIGNMENT_8B
2463 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2464 # except Kconfig can't do arithmetic :/
2465 config FUNCTION_PADDING_BYTES
2467 default FUNCTION_PADDING_CFI if CFI_CLANG
2468 default FUNCTION_ALIGNMENT
2472 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2473 select FUNCTION_ALIGNMENT_16B
2477 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2480 config HAVE_CALL_THUNKS
2482 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2488 config PREFIX_SYMBOLS
2490 depends on CALL_PADDING && !CFI_CLANG
2492 menuconfig SPECULATION_MITIGATIONS
2493 bool "Mitigations for speculative execution vulnerabilities"
2496 Say Y here to enable options which enable mitigations for
2497 speculative execution hardware vulnerabilities.
2499 If you say N, all mitigations will be disabled. You really
2500 should know what you are doing to say so.
2502 if SPECULATION_MITIGATIONS
2504 config PAGE_TABLE_ISOLATION
2505 bool "Remove the kernel mapping in user mode"
2507 depends on (X86_64 || X86_PAE)
2509 This feature reduces the number of hardware side channels by
2510 ensuring that the majority of kernel addresses are not mapped
2513 See Documentation/arch/x86/pti.rst for more details.
2516 bool "Avoid speculative indirect branches in kernel"
2517 select OBJTOOL if HAVE_OBJTOOL
2520 Compile kernel with the retpoline compiler options to guard against
2521 kernel-to-user data leaks by avoiding speculative indirect
2522 branches. Requires a compiler with -mindirect-branch=thunk-extern
2523 support for full protection. The kernel may run slower.
2526 bool "Enable return-thunks"
2527 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2528 select OBJTOOL if HAVE_OBJTOOL
2531 Compile the kernel with the return-thunks compiler option to guard
2532 against kernel-to-user data leaks by avoiding return speculation.
2533 Requires a compiler with -mfunction-return=thunk-extern
2534 support for full protection. The kernel may run slower.
2536 config CPU_UNRET_ENTRY
2537 bool "Enable UNRET on kernel entry"
2538 depends on CPU_SUP_AMD && RETHUNK && X86_64
2541 Compile the kernel with support for the retbleed=unret mitigation.
2543 config CALL_DEPTH_TRACKING
2544 bool "Mitigate RSB underflow with call depth tracking"
2545 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2546 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2550 Compile the kernel with call depth tracking to mitigate the Intel
2551 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2552 mitigation is off by default and needs to be enabled on the
2553 kernel command line via the retbleed=stuff option. For
2554 non-affected systems the overhead of this option is marginal as
2555 the call depth tracking is using run-time generated call thunks
2556 in a compiler generated padding area and call patching. This
2557 increases text size by ~5%. For non affected systems this space
2558 is unused. On affected SKL systems this results in a significant
2559 performance gain over the IBRS mitigation.
2561 config CALL_THUNKS_DEBUG
2562 bool "Enable call thunks and call depth tracking debugging"
2563 depends on CALL_DEPTH_TRACKING
2564 select FUNCTION_ALIGNMENT_32B
2567 Enable call/ret counters for imbalance detection and build in
2568 a noisy dmesg about callthunks generation and call patching for
2569 trouble shooting. The debug prints need to be enabled on the
2570 kernel command line with 'debug-callthunks'.
2571 Only enable this when you are debugging call thunks as this
2572 creates a noticeable runtime overhead. If unsure say N.
2574 config CPU_IBPB_ENTRY
2575 bool "Enable IBPB on kernel entry"
2576 depends on CPU_SUP_AMD && X86_64
2579 Compile the kernel with support for the retbleed=ibpb mitigation.
2581 config CPU_IBRS_ENTRY
2582 bool "Enable IBRS on kernel entry"
2583 depends on CPU_SUP_INTEL && X86_64
2586 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2587 This mitigates both spectre_v2 and retbleed at great cost to
2591 bool "Mitigate speculative RAS overflow on AMD"
2592 depends on CPU_SUP_AMD && X86_64 && RETHUNK
2595 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2598 bool "Mitigate Straight-Line-Speculation"
2599 depends on CC_HAS_SLS && X86_64
2600 select OBJTOOL if HAVE_OBJTOOL
2603 Compile the kernel with straight-line-speculation options to guard
2604 against straight line speculation. The kernel image might be slightly
2607 config GDS_FORCE_MITIGATION
2608 bool "Force GDS Mitigation"
2609 depends on CPU_SUP_INTEL
2612 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2613 unprivileged speculative access to data which was previously stored in
2616 This option is equivalent to setting gather_data_sampling=force on the
2617 command line. The microcode mitigation is used if present, otherwise
2618 AVX is disabled as a mitigation. On affected systems that are missing
2619 the microcode any userspace code that unconditionally uses AVX will
2620 break with this option set.
2622 Setting this option on systems not vulnerable to GDS has no effect.
2628 config ARCH_HAS_ADD_PAGES
2630 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2632 menu "Power management and ACPI options"
2634 config ARCH_HIBERNATION_HEADER
2636 depends on HIBERNATION
2638 source "kernel/power/Kconfig"
2640 source "drivers/acpi/Kconfig"
2647 tristate "APM (Advanced Power Management) BIOS support"
2648 depends on X86_32 && PM_SLEEP
2650 APM is a BIOS specification for saving power using several different
2651 techniques. This is mostly useful for battery powered laptops with
2652 APM compliant BIOSes. If you say Y here, the system time will be
2653 reset after a RESUME operation, the /proc/apm device will provide
2654 battery status information, and user-space programs will receive
2655 notification of APM "events" (e.g. battery status change).
2657 If you select "Y" here, you can disable actual use of the APM
2658 BIOS by passing the "apm=off" option to the kernel at boot time.
2660 Note that the APM support is almost completely disabled for
2661 machines with more than one CPU.
2663 In order to use APM, you will need supporting software. For location
2664 and more information, read <file:Documentation/power/apm-acpi.rst>
2665 and the Battery Powered Linux mini-HOWTO, available from
2666 <http://www.tldp.org/docs.html#howto>.
2668 This driver does not spin down disk drives (see the hdparm(8)
2669 manpage ("man 8 hdparm") for that), and it doesn't turn off
2670 VESA-compliant "green" monitors.
2672 This driver does not support the TI 4000M TravelMate and the ACER
2673 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2674 desktop machines also don't have compliant BIOSes, and this driver
2675 may cause those machines to panic during the boot phase.
2677 Generally, if you don't have a battery in your machine, there isn't
2678 much point in using this driver and you should say N. If you get
2679 random kernel OOPSes or reboots that don't seem to be related to
2680 anything, try disabling/enabling this option (or disabling/enabling
2683 Some other things you should try when experiencing seemingly random,
2686 1) make sure that you have enough swap space and that it is
2688 2) pass the "idle=poll" option to the kernel
2689 3) switch on floating point emulation in the kernel and pass
2690 the "no387" option to the kernel
2691 4) pass the "floppy=nodma" option to the kernel
2692 5) pass the "mem=4M" option to the kernel (thereby disabling
2693 all but the first 4 MB of RAM)
2694 6) make sure that the CPU is not over clocked.
2695 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2696 8) disable the cache from your BIOS settings
2697 9) install a fan for the video card or exchange video RAM
2698 10) install a better fan for the CPU
2699 11) exchange RAM chips
2700 12) exchange the motherboard.
2702 To compile this driver as a module, choose M here: the
2703 module will be called apm.
2707 config APM_IGNORE_USER_SUSPEND
2708 bool "Ignore USER SUSPEND"
2710 This option will ignore USER SUSPEND requests. On machines with a
2711 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2712 series notebooks, it is necessary to say Y because of a BIOS bug.
2714 config APM_DO_ENABLE
2715 bool "Enable PM at boot time"
2717 Enable APM features at boot time. From page 36 of the APM BIOS
2718 specification: "When disabled, the APM BIOS does not automatically
2719 power manage devices, enter the Standby State, enter the Suspend
2720 State, or take power saving steps in response to CPU Idle calls."
2721 This driver will make CPU Idle calls when Linux is idle (unless this
2722 feature is turned off -- see "Do CPU IDLE calls", below). This
2723 should always save battery power, but more complicated APM features
2724 will be dependent on your BIOS implementation. You may need to turn
2725 this option off if your computer hangs at boot time when using APM
2726 support, or if it beeps continuously instead of suspending. Turn
2727 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2728 T400CDT. This is off by default since most machines do fine without
2733 bool "Make CPU Idle calls when idle"
2735 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2736 On some machines, this can activate improved power savings, such as
2737 a slowed CPU clock rate, when the machine is idle. These idle calls
2738 are made after the idle loop has run for some length of time (e.g.,
2739 333 mS). On some machines, this will cause a hang at boot time or
2740 whenever the CPU becomes idle. (On machines with more than one CPU,
2741 this option does nothing.)
2743 config APM_DISPLAY_BLANK
2744 bool "Enable console blanking using APM"
2746 Enable console blanking using the APM. Some laptops can use this to
2747 turn off the LCD backlight when the screen blanker of the Linux
2748 virtual console blanks the screen. Note that this is only used by
2749 the virtual console screen blanker, and won't turn off the backlight
2750 when using the X Window system. This also doesn't have anything to
2751 do with your VESA-compliant power-saving monitor. Further, this
2752 option doesn't work for all laptops -- it might not turn off your
2753 backlight at all, or it might print a lot of errors to the console,
2754 especially if you are using gpm.
2756 config APM_ALLOW_INTS
2757 bool "Allow interrupts during APM BIOS calls"
2759 Normally we disable external interrupts while we are making calls to
2760 the APM BIOS as a measure to lessen the effects of a badly behaving
2761 BIOS implementation. The BIOS should reenable interrupts if it
2762 needs to. Unfortunately, some BIOSes do not -- especially those in
2763 many of the newer IBM Thinkpads. If you experience hangs when you
2764 suspend, try setting this to Y. Otherwise, say N.
2768 source "drivers/cpufreq/Kconfig"
2770 source "drivers/cpuidle/Kconfig"
2772 source "drivers/idle/Kconfig"
2776 menu "Bus options (PCI etc.)"
2779 prompt "PCI access mode"
2780 depends on X86_32 && PCI
2783 On PCI systems, the BIOS can be used to detect the PCI devices and
2784 determine their configuration. However, some old PCI motherboards
2785 have BIOS bugs and may crash if this is done. Also, some embedded
2786 PCI-based systems don't have any BIOS at all. Linux can also try to
2787 detect the PCI hardware directly without using the BIOS.
2789 With this option, you can specify how Linux should detect the
2790 PCI devices. If you choose "BIOS", the BIOS will be used,
2791 if you choose "Direct", the BIOS won't be used, and if you
2792 choose "MMConfig", then PCI Express MMCONFIG will be used.
2793 If you choose "Any", the kernel will try MMCONFIG, then the
2794 direct access method and falls back to the BIOS if that doesn't
2795 work. If unsure, go with the default, which is "Any".
2800 config PCI_GOMMCONFIG
2817 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2819 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2822 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2825 bool "Support mmconfig PCI config space access" if X86_64
2827 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2828 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2832 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2836 depends on PCI && XEN
2838 config MMCONF_FAM10H
2840 depends on X86_64 && PCI_MMCONFIG && ACPI
2842 config PCI_CNB20LE_QUIRK
2843 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2846 Read the PCI windows out of the CNB20LE host bridge. This allows
2847 PCI hotplug to work on systems with the CNB20LE chipset which do
2850 There's no public spec for this chipset, and this functionality
2851 is known to be incomplete.
2853 You should say N unless you know you need this.
2856 bool "ISA bus support on modern systems" if EXPERT
2858 Expose ISA bus device drivers and options available for selection and
2859 configuration. Enable this option if your target machine has an ISA
2860 bus. ISA is an older system, displaced by PCI and newer bus
2861 architectures -- if your target machine is modern, it probably does
2862 not have an ISA bus.
2866 # x86_64 have no ISA slots, but can have ISA-style DMA.
2868 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2871 Enables ISA-style DMA support for devices requiring such controllers.
2879 Find out whether you have ISA slots on your motherboard. ISA is the
2880 name of a bus system, i.e. the way the CPU talks to the other stuff
2881 inside your box. Other bus systems are PCI, EISA, MicroChannel
2882 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2883 newer boards don't support it. If you have ISA, say Y, otherwise N.
2886 tristate "NatSemi SCx200 support"
2888 This provides basic support for National Semiconductor's
2889 (now AMD's) Geode processors. The driver probes for the
2890 PCI-IDs of several on-chip devices, so its a good dependency
2891 for other scx200_* drivers.
2893 If compiled as a module, the driver is named scx200.
2895 config SCx200HR_TIMER
2896 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2900 This driver provides a clocksource built upon the on-chip
2901 27MHz high-resolution timer. Its also a workaround for
2902 NSC Geode SC-1100's buggy TSC, which loses time when the
2903 processor goes idle (as is done by the scheduler). The
2904 other workaround is idle=poll boot option.
2907 bool "One Laptop Per Child support"
2915 Add support for detecting the unique features of the OLPC
2919 bool "OLPC XO-1 Power Management"
2920 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2922 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2925 bool "OLPC XO-1 Real Time Clock"
2926 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2928 Add support for the XO-1 real time clock, which can be used as a
2929 programmable wakeup source.
2932 bool "OLPC XO-1 SCI extras"
2933 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2937 Add support for SCI-based features of the OLPC XO-1 laptop:
2938 - EC-driven system wakeups
2942 - AC adapter status updates
2943 - Battery status updates
2945 config OLPC_XO15_SCI
2946 bool "OLPC XO-1.5 SCI extras"
2947 depends on OLPC && ACPI
2950 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2951 - EC-driven system wakeups
2952 - AC adapter status updates
2953 - Battery status updates
2956 bool "PCEngines ALIX System Support (LED setup)"
2959 This option enables system support for the PCEngines ALIX.
2960 At present this just sets up LEDs for GPIO control on
2961 ALIX2/3/6 boards. However, other system specific setup should
2964 Note: You must still enable the drivers for GPIO and LED support
2965 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2967 Note: You have to set alix.force=1 for boards with Award BIOS.
2970 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2973 This option enables system support for the Soekris Engineering net5501.
2976 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2980 This option enables system support for the Traverse Technologies GEOS.
2983 bool "Technologic Systems TS-5500 platform support"
2985 select CHECK_SIGNATURE
2989 This option enables system support for the Technologic Systems TS-5500.
2995 depends on CPU_SUP_AMD && PCI
2999 menu "Binary Emulations"
3001 config IA32_EMULATION
3002 bool "IA32 Emulation"
3004 select ARCH_WANT_OLD_COMPAT_IPC
3006 select COMPAT_OLD_SIGACTION
3008 Include code to run legacy 32-bit programs under a
3009 64-bit kernel. You should likely turn this on, unless you're
3010 100% sure that you don't have any 32-bit programs left.
3012 config IA32_EMULATION_DEFAULT_DISABLED
3013 bool "IA32 emulation disabled by default"
3015 depends on IA32_EMULATION
3017 Make IA32 emulation disabled by default. This prevents loading 32-bit
3018 processes and access to 32-bit syscalls. If unsure, leave it to its
3022 bool "x32 ABI for 64-bit mode"
3024 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3025 # compressed debug sections to x86_x32 properly:
3026 # https://github.com/ClangBuiltLinux/linux/issues/514
3027 # https://github.com/ClangBuiltLinux/linux/issues/1141
3028 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3030 Include code to run binaries for the x32 native 32-bit ABI
3031 for 64-bit processors. An x32 process gets access to the
3032 full 64-bit register file and wide data path while leaving
3033 pointers at 32 bits for smaller memory footprint.
3037 depends on IA32_EMULATION || X86_32
3039 select OLD_SIGSUSPEND3
3043 depends on IA32_EMULATION || X86_X32_ABI
3045 config COMPAT_FOR_U64_ALIGNMENT
3051 config HAVE_ATOMIC_IOMAP
3055 source "arch/x86/kvm/Kconfig"
3057 source "arch/x86/Kconfig.assembler"