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
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_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST
151 select GENERIC_CLOCKEVENTS_MIN_ADJUST
152 select GENERIC_CMOS_UPDATE
153 select GENERIC_CPU_AUTOPROBE
154 select GENERIC_CPU_DEVICES
155 select GENERIC_CPU_VULNERABILITIES
156 select GENERIC_EARLY_IOREMAP
159 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
160 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
161 select GENERIC_IRQ_MIGRATION if SMP
162 select GENERIC_IRQ_PROBE
163 select GENERIC_IRQ_RESERVATION_MODE
164 select GENERIC_IRQ_SHOW
165 select GENERIC_PENDING_IRQ if SMP
166 select GENERIC_PTDUMP
167 select GENERIC_SMP_IDLE_THREAD
168 select GENERIC_TIME_VSYSCALL
169 select GENERIC_GETTIMEOFDAY
170 select GENERIC_VDSO_TIME_NS
171 select GUP_GET_PXX_LOW_HIGH if X86_PAE
172 select HARDIRQS_SW_RESEND
173 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
175 select HAVE_ACPI_APEI if ACPI
176 select HAVE_ACPI_APEI_NMI if ACPI
177 select HAVE_ALIGNED_STRUCT_PAGE
178 select HAVE_ARCH_AUDITSYSCALL
179 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
180 select HAVE_ARCH_HUGE_VMALLOC if X86_64
181 select HAVE_ARCH_JUMP_LABEL
182 select HAVE_ARCH_JUMP_LABEL_RELATIVE
183 select HAVE_ARCH_KASAN if X86_64
184 select HAVE_ARCH_KASAN_VMALLOC if X86_64
185 select HAVE_ARCH_KFENCE
186 select HAVE_ARCH_KMSAN if X86_64
187 select HAVE_ARCH_KGDB
188 select HAVE_ARCH_MMAP_RND_BITS if MMU
189 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
190 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
191 select HAVE_ARCH_PREL32_RELOCATIONS
192 select HAVE_ARCH_SECCOMP_FILTER
193 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
194 select HAVE_ARCH_STACKLEAK
195 select HAVE_ARCH_TRACEHOOK
196 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
197 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
198 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
199 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
200 select HAVE_ARCH_VMAP_STACK if X86_64
201 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
202 select HAVE_ARCH_WITHIN_STACK_FRAMES
203 select HAVE_ASM_MODVERSIONS
204 select HAVE_CMPXCHG_DOUBLE
205 select HAVE_CMPXCHG_LOCAL
206 select HAVE_CONTEXT_TRACKING_USER if X86_64
207 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
208 select HAVE_C_RECORDMCOUNT
209 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
210 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
211 select HAVE_BUILDTIME_MCOUNT_SORT
212 select HAVE_DEBUG_KMEMLEAK
213 select HAVE_DMA_CONTIGUOUS
214 select HAVE_DYNAMIC_FTRACE
215 select HAVE_DYNAMIC_FTRACE_WITH_REGS
216 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
217 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
218 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
219 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
221 select HAVE_EFFICIENT_UNALIGNED_ACCESS
223 select HAVE_EXIT_THREAD
225 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
226 select HAVE_FTRACE_MCOUNT_RECORD
227 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
228 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
229 select HAVE_FUNCTION_TRACER
230 select HAVE_GCC_PLUGINS
231 select HAVE_HW_BREAKPOINT
232 select HAVE_IOREMAP_PROT
233 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
234 select HAVE_IRQ_TIME_ACCOUNTING
235 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
236 select HAVE_KERNEL_BZIP2
237 select HAVE_KERNEL_GZIP
238 select HAVE_KERNEL_LZ4
239 select HAVE_KERNEL_LZMA
240 select HAVE_KERNEL_LZO
241 select HAVE_KERNEL_XZ
242 select HAVE_KERNEL_ZSTD
244 select HAVE_KPROBES_ON_FTRACE
245 select HAVE_FUNCTION_ERROR_INJECTION
246 select HAVE_KRETPROBES
249 select HAVE_LIVEPATCH if X86_64
250 select HAVE_MIXED_BREAKPOINTS_REGS
251 select HAVE_MOD_ARCH_SPECIFIC
254 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
256 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
257 select HAVE_OBJTOOL if X86_64
258 select HAVE_OPTPROBES
259 select HAVE_PAGE_SIZE_4KB
260 select HAVE_PCSPKR_PLATFORM
261 select HAVE_PERF_EVENTS
262 select HAVE_PERF_EVENTS_NMI
263 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
265 select HAVE_PERF_REGS
266 select HAVE_PERF_USER_STACK_DUMP
267 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
268 select MMU_GATHER_MERGE_VMAS
269 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
270 select HAVE_REGS_AND_STACK_ACCESS_API
271 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
272 select HAVE_FUNCTION_ARG_ACCESS_API
273 select HAVE_SETUP_PER_CPU_AREA
274 select HAVE_SOFTIRQ_ON_OWN_STACK
275 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
276 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
277 select HAVE_STATIC_CALL
278 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
279 select HAVE_PREEMPT_DYNAMIC_CALL
281 select HAVE_RUST if X86_64
282 select HAVE_SYSCALL_TRACEPOINTS
283 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
284 select HAVE_UNSTABLE_SCHED_CLOCK
285 select HAVE_USER_RETURN_NOTIFIER
286 select HAVE_GENERIC_VDSO
287 select HOTPLUG_PARALLEL if SMP && X86_64
288 select HOTPLUG_SMT if SMP
289 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
290 select IRQ_FORCED_THREADING
291 select LOCK_MM_AND_FIND_VMA
292 select NEED_PER_CPU_EMBED_FIRST_CHUNK
293 select NEED_PER_CPU_PAGE_FIRST_CHUNK
294 select NEED_SG_DMA_LENGTH
295 select PCI_DOMAINS if PCI
296 select PCI_LOCKLESS_CONFIG if PCI
299 select RTC_MC146818_LIB
301 select SYSCTL_EXCEPTION_TRACE
302 select THREAD_INFO_IN_TASK
303 select TRACE_IRQFLAGS_SUPPORT
304 select TRACE_IRQFLAGS_NMI_SUPPORT
305 select USER_STACKTRACE_SUPPORT
306 select HAVE_ARCH_KCSAN if X86_64
307 select PROC_PID_ARCH_STATUS if PROC_FS
308 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
309 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
310 select FUNCTION_ALIGNMENT_4B
311 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
312 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
314 config INSTRUCTION_DECODER
316 depends on KPROBES || PERF_EVENTS || UPROBES
320 default "elf32-i386" if X86_32
321 default "elf64-x86-64" if X86_64
323 config LOCKDEP_SUPPORT
326 config STACKTRACE_SUPPORT
332 config ARCH_MMAP_RND_BITS_MIN
336 config ARCH_MMAP_RND_BITS_MAX
340 config ARCH_MMAP_RND_COMPAT_BITS_MIN
343 config ARCH_MMAP_RND_COMPAT_BITS_MAX
349 config GENERIC_ISA_DMA
351 depends on ISA_DMA_API
355 default y if KMSAN || KASAN
360 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
362 config GENERIC_BUG_RELATIVE_POINTERS
365 config ARCH_MAY_HAVE_PC_FDC
367 depends on ISA_DMA_API
369 config GENERIC_CALIBRATE_DELAY
372 config ARCH_HAS_CPU_RELAX
375 config ARCH_HIBERNATION_POSSIBLE
378 config ARCH_SUSPEND_POSSIBLE
384 config KASAN_SHADOW_OFFSET
387 default 0xdffffc0000000000
389 config HAVE_INTEL_TXT
391 depends on INTEL_IOMMU && ACPI
395 depends on X86_64 && SMP
397 config ARCH_SUPPORTS_UPROBES
400 config FIX_EARLYCON_MEM
403 config DYNAMIC_PHYSICAL_MASK
406 config PGTABLE_LEVELS
408 default 5 if X86_5LEVEL
413 config CC_HAS_SANE_STACKPROTECTOR
415 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
416 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
418 We have to make sure stack protector is unconditionally disabled if
419 the compiler produces broken code or if it does not let us control
420 the segment on 32-bit kernels.
422 menu "Processor type and features"
425 bool "Symmetric multi-processing support"
427 This enables support for systems with more than one CPU. If you have
428 a system with only one CPU, say N. If you have a system with more
431 If you say N here, the kernel will run on uni- and multiprocessor
432 machines, but will use only one CPU of a multiprocessor machine. If
433 you say Y here, the kernel will run on many, but not all,
434 uniprocessor machines. On a uniprocessor machine, the kernel
435 will run faster if you say N here.
437 Note that if you say Y here and choose architecture "586" or
438 "Pentium" under "Processor family", the kernel will not work on 486
439 architectures. Similarly, multiprocessor kernels for the "PPro"
440 architecture may not work on all Pentium based boards.
442 People using multiprocessor machines who say Y here should also say
443 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
444 Management" code will be disabled if you say Y here.
446 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
447 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
448 <http://www.tldp.org/docs.html#howto>.
450 If you don't know what to do here, say N.
453 bool "Support x2apic"
454 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
456 This enables x2apic support on CPUs that have this feature.
458 This allows 32-bit apic IDs (so it can support very large systems),
459 and accesses the local apic via MSRs not via mmio.
461 Some Intel systems circa 2022 and later are locked into x2APIC mode
462 and can not fall back to the legacy APIC modes if SGX or TDX are
463 enabled in the BIOS. They will boot with very reduced functionality
464 without enabling this option.
466 If you don't know what to do here, say N.
469 bool "Enable MPS table" if ACPI
471 depends on X86_LOCAL_APIC
473 For old smp systems that do not have proper acpi support. Newer systems
474 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
478 depends on X86_GOLDFISH
480 config X86_CPU_RESCTRL
481 bool "x86 CPU resource control support"
482 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
484 select PROC_CPU_RESCTRL if PROC_FS
486 Enable x86 CPU resource control support.
488 Provide support for the allocation and monitoring of system resources
491 Intel calls this Intel Resource Director Technology
492 (Intel(R) RDT). More information about RDT can be found in the
493 Intel x86 Architecture Software Developer Manual.
495 AMD calls this AMD Platform Quality of Service (AMD QoS).
496 More information about AMD QoS can be found in the AMD64 Technology
497 Platform Quality of Service Extensions manual.
502 bool "Flexible Return and Event Delivery"
505 When enabled, try to use Flexible Return and Event Delivery
506 instead of the legacy SYSCALL/SYSENTER/IDT architecture for
507 ring transitions and exception/interrupt handling if the
512 bool "Support for big SMP systems with more than 8 CPUs"
515 This option is needed for the systems that have more than 8 CPUs.
517 config X86_EXTENDED_PLATFORM
518 bool "Support for extended (non-PC) x86 platforms"
521 If you disable this option then the kernel will only support
522 standard PC platforms. (which covers the vast majority of
525 If you enable this option then you'll be able to select support
526 for the following (non-PC) 32 bit x86 platforms:
527 Goldfish (Android emulator)
530 SGI 320/540 (Visual Workstation)
531 STA2X11-based (e.g. Northville)
532 Moorestown MID devices
534 If you have one of these systems, or if you want to build a
535 generic distribution kernel, say Y here - otherwise say N.
539 config X86_EXTENDED_PLATFORM
540 bool "Support for extended (non-PC) x86 platforms"
543 If you disable this option then the kernel will only support
544 standard PC platforms. (which covers the vast majority of
547 If you enable this option then you'll be able to select support
548 for the following (non-PC) 64 bit x86 platforms:
553 If you have one of these systems, or if you want to build a
554 generic distribution kernel, say Y here - otherwise say N.
556 # This is an alphabetically sorted list of 64 bit extended platforms
557 # Please maintain the alphabetic order if and when there are additions
559 bool "Numascale NumaChip"
561 depends on X86_EXTENDED_PLATFORM
564 depends on X86_X2APIC
565 depends on PCI_MMCONFIG
567 Adds support for Numascale NumaChip large-SMP systems. Needed to
568 enable more than ~168 cores.
569 If you don't have one of these, you should say N here.
573 select HYPERVISOR_GUEST
575 depends on X86_64 && PCI
576 depends on X86_EXTENDED_PLATFORM
579 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
580 supposed to run on these EM64T-based machines. Only choose this option
581 if you have one of these machines.
584 bool "SGI Ultraviolet"
586 depends on X86_EXTENDED_PLATFORM
589 depends on KEXEC_CORE
590 depends on X86_X2APIC
593 This option is needed in order to support SGI Ultraviolet systems.
594 If you don't have one of these, you should say N here.
596 # Following is an alphabetically sorted list of 32 bit extended platforms
597 # Please maintain the alphabetic order if and when there are additions
600 bool "Goldfish (Virtual Platform)"
601 depends on X86_EXTENDED_PLATFORM
603 Enable support for the Goldfish virtual platform used primarily
604 for Android development. Unless you are building for the Android
605 Goldfish emulator say N here.
608 bool "CE4100 TV platform"
610 depends on PCI_GODIRECT
611 depends on X86_IO_APIC
613 depends on X86_EXTENDED_PLATFORM
614 select X86_REBOOTFIXUPS
616 select OF_EARLY_FLATTREE
618 Select for the Intel CE media processor (CE4100) SOC.
619 This option compiles in support for the CE4100 SOC for settop
620 boxes and media devices.
623 bool "Intel MID platform support"
624 depends on X86_EXTENDED_PLATFORM
625 depends on X86_PLATFORM_DEVICES
627 depends on X86_64 || (PCI_GOANY && X86_32)
628 depends on X86_IO_APIC
633 Select to build a kernel capable of supporting Intel MID (Mobile
634 Internet Device) platform systems which do not have the PCI legacy
635 interfaces. If you are building for a PC class system say N here.
637 Intel MID platforms are based on an Intel processor and chipset which
638 consume less power than most of the x86 derivatives.
640 config X86_INTEL_QUARK
641 bool "Intel Quark platform support"
643 depends on X86_EXTENDED_PLATFORM
644 depends on X86_PLATFORM_DEVICES
648 depends on X86_IO_APIC
653 Select to include support for Quark X1000 SoC.
654 Say Y here if you have a Quark based system such as the Arduino
655 compatible Intel Galileo.
657 config X86_INTEL_LPSS
658 bool "Intel Low Power Subsystem Support"
659 depends on X86 && ACPI && PCI
664 Select to build support for Intel Low Power Subsystem such as
665 found on Intel Lynxpoint PCH. Selecting this option enables
666 things like clock tree (common clock framework) and pincontrol
667 which are needed by the LPSS peripheral drivers.
669 config X86_AMD_PLATFORM_DEVICE
670 bool "AMD ACPI2Platform devices support"
675 Select to interpret AMD specific ACPI device to platform device
676 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
677 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
678 implemented under PINCTRL subsystem.
681 tristate "Intel SoC IOSF Sideband support for SoC platforms"
684 This option enables sideband register access support for Intel SoC
685 platforms. On these platforms the IOSF sideband is used in lieu of
686 MSR's for some register accesses, mostly but not limited to thermal
687 and power. Drivers may query the availability of this device to
688 determine if they need the sideband in order to work on these
689 platforms. The sideband is available on the following SoC products.
690 This list is not meant to be exclusive.
695 You should say Y if you are running a kernel on one of these SoC's.
697 config IOSF_MBI_DEBUG
698 bool "Enable IOSF sideband access through debugfs"
699 depends on IOSF_MBI && DEBUG_FS
701 Select this option to expose the IOSF sideband access registers (MCR,
702 MDR, MCRX) through debugfs to write and read register information from
703 different units on the SoC. This is most useful for obtaining device
704 state information for debug and analysis. As this is a general access
705 mechanism, users of this option would have specific knowledge of the
706 device they want to access.
708 If you don't require the option or are in doubt, say N.
711 bool "RDC R-321x SoC"
713 depends on X86_EXTENDED_PLATFORM
715 select X86_REBOOTFIXUPS
717 This option is needed for RDC R-321x system-on-chip, also known
719 If you don't have one of these chips, you should say N here.
721 config X86_32_NON_STANDARD
722 bool "Support non-standard 32-bit SMP architectures"
723 depends on X86_32 && SMP
724 depends on X86_EXTENDED_PLATFORM
726 This option compiles in the bigsmp and STA2X11 default
727 subarchitectures. It is intended for a generic binary
728 kernel. If you select them all, kernel will probe it one by
729 one and will fallback to default.
731 # Alphabetically sorted list of Non standard 32 bit platforms
733 config X86_SUPPORTS_MEMORY_FAILURE
735 # MCE code calls memory_failure():
737 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
738 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
739 depends on X86_64 || !SPARSEMEM
740 select ARCH_SUPPORTS_MEMORY_FAILURE
743 bool "STA2X11 Companion Chip Support"
744 depends on X86_32_NON_STANDARD && PCI
749 This adds support for boards based on the STA2X11 IO-Hub,
750 a.k.a. "ConneXt". The chip is used in place of the standard
751 PC chipset, so all "standard" peripherals are missing. If this
752 option is selected the kernel will still be able to boot on
753 standard PC machines.
756 tristate "Eurobraille/Iris poweroff module"
759 The Iris machines from EuroBraille do not have APM or ACPI support
760 to shut themselves down properly. A special I/O sequence is
761 needed to do so, which is what this module does at
764 This is only for Iris machines from EuroBraille.
768 config SCHED_OMIT_FRAME_POINTER
770 prompt "Single-depth WCHAN output"
773 Calculate simpler /proc/<PID>/wchan values. If this option
774 is disabled then wchan values will recurse back to the
775 caller function. This provides more accurate wchan values,
776 at the expense of slightly more scheduling overhead.
778 If in doubt, say "Y".
780 menuconfig HYPERVISOR_GUEST
781 bool "Linux guest support"
783 Say Y here to enable options for running Linux under various hyper-
784 visors. This option enables basic hypervisor detection and platform
787 If you say N, all options in this submenu will be skipped and
788 disabled, and Linux guest support won't be built in.
793 bool "Enable paravirtualization code"
794 depends on HAVE_STATIC_CALL
796 This changes the kernel so it can modify itself when it is run
797 under a hypervisor, potentially improving performance significantly
798 over full virtualization. However, when run without a hypervisor
799 the kernel is theoretically slower and slightly larger.
804 config PARAVIRT_DEBUG
805 bool "paravirt-ops debugging"
806 depends on PARAVIRT && DEBUG_KERNEL
808 Enable to debug paravirt_ops internals. Specifically, BUG if
809 a paravirt_op is missing when it is called.
811 config PARAVIRT_SPINLOCKS
812 bool "Paravirtualization layer for spinlocks"
813 depends on PARAVIRT && SMP
815 Paravirtualized spinlocks allow a pvops backend to replace the
816 spinlock implementation with something virtualization-friendly
817 (for example, block the virtual CPU rather than spinning).
819 It has a minimal impact on native kernels and gives a nice performance
820 benefit on paravirtualized KVM / Xen kernels.
822 If you are unsure how to answer this question, answer Y.
824 config X86_HV_CALLBACK_VECTOR
827 source "arch/x86/xen/Kconfig"
830 bool "KVM Guest support (including kvmclock)"
832 select PARAVIRT_CLOCK
833 select ARCH_CPUIDLE_HALTPOLL
834 select X86_HV_CALLBACK_VECTOR
837 This option enables various optimizations for running under the KVM
838 hypervisor. It includes a paravirtualized clock, so that instead
839 of relying on a PIT (or probably other) emulation by the
840 underlying device model, the host provides the guest with
841 timing infrastructure such as time of day, and system time
843 config ARCH_CPUIDLE_HALTPOLL
845 prompt "Disable host haltpoll when loading haltpoll driver"
847 If virtualized under KVM, disable host haltpoll.
850 bool "Support for running PVH guests"
852 This option enables the PVH entry point for guest virtual machines
853 as specified in the x86/HVM direct boot ABI.
855 config PARAVIRT_TIME_ACCOUNTING
856 bool "Paravirtual steal time accounting"
859 Select this option to enable fine granularity task steal time
860 accounting. Time spent executing other tasks in parallel with
861 the current vCPU is discounted from the vCPU power. To account for
862 that, there can be a small performance impact.
864 If in doubt, say N here.
866 config PARAVIRT_CLOCK
869 config JAILHOUSE_GUEST
870 bool "Jailhouse non-root cell support"
871 depends on X86_64 && PCI
874 This option allows to run Linux as guest in a Jailhouse non-root
875 cell. You can leave this option disabled if you only want to start
876 Jailhouse and run Linux afterwards in the root cell.
879 bool "ACRN Guest support"
881 select X86_HV_CALLBACK_VECTOR
883 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
884 a flexible, lightweight reference open-source hypervisor, built with
885 real-time and safety-criticality in mind. It is built for embedded
886 IOT with small footprint and real-time features. More details can be
887 found in https://projectacrn.org/.
889 config INTEL_TDX_GUEST
890 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
891 depends on X86_64 && CPU_SUP_INTEL
892 depends on X86_X2APIC
894 select ARCH_HAS_CC_PLATFORM
895 select X86_MEM_ENCRYPT
897 select UNACCEPTED_MEMORY
899 Support running as a guest under Intel TDX. Without this support,
900 the guest kernel can not boot or run under TDX.
901 TDX includes memory encryption and integrity capabilities
902 which protect the confidentiality and integrity of guest
903 memory contents and CPU state. TDX guests are protected from
904 some attacks from the VMM.
906 endif # HYPERVISOR_GUEST
908 source "arch/x86/Kconfig.cpu"
912 prompt "HPET Timer Support" if X86_32
914 Use the IA-PC HPET (High Precision Event Timer) to manage
915 time in preference to the PIT and RTC, if a HPET is
917 HPET is the next generation timer replacing legacy 8254s.
918 The HPET provides a stable time base on SMP
919 systems, unlike the TSC, but it is more expensive to access,
920 as it is off-chip. The interface used is documented
921 in the HPET spec, revision 1.
923 You can safely choose Y here. However, HPET will only be
924 activated if the platform and the BIOS support this feature.
925 Otherwise the 8254 will be used for timing services.
927 Choose N to continue using the legacy 8254 timer.
929 config HPET_EMULATE_RTC
931 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
933 # Mark as expert because too many people got it wrong.
934 # The code disables itself when not needed.
937 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
938 bool "Enable DMI scanning" if EXPERT
940 Enabled scanning of DMI to identify machine quirks. Say Y
941 here unless you have verified that your setup is not
942 affected by entries in the DMI blacklist. Required by PNP
946 bool "Old AMD GART IOMMU support"
950 depends on X86_64 && PCI && AMD_NB
952 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
953 GART based hardware IOMMUs.
955 The GART supports full DMA access for devices with 32-bit access
956 limitations, on systems with more than 3 GB. This is usually needed
957 for USB, sound, many IDE/SATA chipsets and some other devices.
959 Newer systems typically have a modern AMD IOMMU, supported via
960 the CONFIG_AMD_IOMMU=y config option.
962 In normal configurations this driver is only active when needed:
963 there's more than 3 GB of memory and the system contains a
964 32-bit limited device.
968 config BOOT_VESA_SUPPORT
971 If true, at least one selected framebuffer driver can take advantage
972 of VESA video modes set at an early boot stage via the vga= parameter.
975 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
976 depends on X86_64 && SMP && DEBUG_KERNEL
977 select CPUMASK_OFFSTACK
979 Enable maximum number of CPUS and NUMA Nodes for this architecture.
983 # The maximum number of CPUs supported:
985 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
986 # and which can be configured interactively in the
987 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
989 # The ranges are different on 32-bit and 64-bit kernels, depending on
990 # hardware capabilities and scalability features of the kernel.
992 # ( If MAXSMP is enabled we just use the highest possible value and disable
993 # interactive configuration. )
996 config NR_CPUS_RANGE_BEGIN
998 default NR_CPUS_RANGE_END if MAXSMP
1002 config NR_CPUS_RANGE_END
1005 default 64 if SMP && X86_BIGSMP
1006 default 8 if SMP && !X86_BIGSMP
1009 config NR_CPUS_RANGE_END
1012 default 8192 if SMP && CPUMASK_OFFSTACK
1013 default 512 if SMP && !CPUMASK_OFFSTACK
1016 config NR_CPUS_DEFAULT
1019 default 32 if X86_BIGSMP
1023 config NR_CPUS_DEFAULT
1026 default 8192 if MAXSMP
1031 int "Maximum number of CPUs" if SMP && !MAXSMP
1032 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1033 default NR_CPUS_DEFAULT
1035 This allows you to specify the maximum number of CPUs which this
1036 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1037 supported value is 8192, otherwise the maximum value is 512. The
1038 minimum value which makes sense is 2.
1040 This is purely to save memory: each supported CPU adds about 8KB
1041 to the kernel image.
1043 config SCHED_CLUSTER
1044 bool "Cluster scheduler support"
1048 Cluster scheduler support improves the CPU scheduler's decision
1049 making when dealing with machines that have clusters of CPUs.
1050 Cluster usually means a couple of CPUs which are placed closely
1051 by sharing mid-level caches, last-level cache tags or internal
1059 prompt "Multi-core scheduler support"
1062 Multi-core scheduler support improves the CPU scheduler's decision
1063 making when dealing with multi-core CPU chips at a cost of slightly
1064 increased overhead in some places. If unsure say N here.
1066 config SCHED_MC_PRIO
1067 bool "CPU core priorities scheduler support"
1068 depends on SCHED_MC && CPU_SUP_INTEL
1069 select X86_INTEL_PSTATE
1073 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1074 core ordering determined at manufacturing time, which allows
1075 certain cores to reach higher turbo frequencies (when running
1076 single threaded workloads) than others.
1078 Enabling this kernel feature teaches the scheduler about
1079 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1080 scheduler's CPU selection logic accordingly, so that higher
1081 overall system performance can be achieved.
1083 This feature will have no effect on CPUs without this feature.
1085 If unsure say Y here.
1089 depends on !SMP && X86_LOCAL_APIC
1092 bool "Local APIC support on uniprocessors" if !PCI_MSI
1094 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1096 A local APIC (Advanced Programmable Interrupt Controller) is an
1097 integrated interrupt controller in the CPU. If you have a single-CPU
1098 system which has a processor with a local APIC, you can say Y here to
1099 enable and use it. If you say Y here even though your machine doesn't
1100 have a local APIC, then the kernel will still run with no slowdown at
1101 all. The local APIC supports CPU-generated self-interrupts (timer,
1102 performance counters), and the NMI watchdog which detects hard
1105 config X86_UP_IOAPIC
1106 bool "IO-APIC support on uniprocessors"
1107 depends on X86_UP_APIC
1109 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1110 SMP-capable replacement for PC-style interrupt controllers. Most
1111 SMP systems and many recent uniprocessor systems have one.
1113 If you have a single-CPU system with an IO-APIC, you can say Y here
1114 to use it. If you say Y here even though your machine doesn't have
1115 an IO-APIC, then the kernel will still run with no slowdown at all.
1117 config X86_LOCAL_APIC
1119 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1120 select IRQ_DOMAIN_HIERARCHY
1124 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1126 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1127 bool "Reroute for broken boot IRQs"
1128 depends on X86_IO_APIC
1130 This option enables a workaround that fixes a source of
1131 spurious interrupts. This is recommended when threaded
1132 interrupt handling is used on systems where the generation of
1133 superfluous "boot interrupts" cannot be disabled.
1135 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1136 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1137 kernel does during interrupt handling). On chipsets where this
1138 boot IRQ generation cannot be disabled, this workaround keeps
1139 the original IRQ line masked so that only the equivalent "boot
1140 IRQ" is delivered to the CPUs. The workaround also tells the
1141 kernel to set up the IRQ handler on the boot IRQ line. In this
1142 way only one interrupt is delivered to the kernel. Otherwise
1143 the spurious second interrupt may cause the kernel to bring
1144 down (vital) interrupt lines.
1146 Only affects "broken" chipsets. Interrupt sharing may be
1147 increased on these systems.
1150 bool "Machine Check / overheating reporting"
1151 select GENERIC_ALLOCATOR
1154 Machine Check support allows the processor to notify the
1155 kernel if it detects a problem (e.g. overheating, data corruption).
1156 The action the kernel takes depends on the severity of the problem,
1157 ranging from warning messages to halting the machine.
1159 config X86_MCELOG_LEGACY
1160 bool "Support for deprecated /dev/mcelog character device"
1163 Enable support for /dev/mcelog which is needed by the old mcelog
1164 userspace logging daemon. Consider switching to the new generation
1167 config X86_MCE_INTEL
1169 prompt "Intel MCE features"
1170 depends on X86_MCE && X86_LOCAL_APIC
1172 Additional support for intel specific MCE features such as
1173 the thermal monitor.
1177 prompt "AMD MCE features"
1178 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1180 Additional support for AMD specific MCE features such as
1181 the DRAM Error Threshold.
1183 config X86_ANCIENT_MCE
1184 bool "Support for old Pentium 5 / WinChip machine checks"
1185 depends on X86_32 && X86_MCE
1187 Include support for machine check handling on old Pentium 5 or WinChip
1188 systems. These typically need to be enabled explicitly on the command
1191 config X86_MCE_THRESHOLD
1192 depends on X86_MCE_AMD || X86_MCE_INTEL
1195 config X86_MCE_INJECT
1196 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1197 tristate "Machine check injector support"
1199 Provide support for injecting machine checks for testing purposes.
1200 If you don't know what a machine check is and you don't do kernel
1201 QA it is safe to say n.
1203 source "arch/x86/events/Kconfig"
1205 config X86_LEGACY_VM86
1206 bool "Legacy VM86 support"
1209 This option allows user programs to put the CPU into V8086
1210 mode, which is an 80286-era approximation of 16-bit real mode.
1212 Some very old versions of X and/or vbetool require this option
1213 for user mode setting. Similarly, DOSEMU will use it if
1214 available to accelerate real mode DOS programs. However, any
1215 recent version of DOSEMU, X, or vbetool should be fully
1216 functional even without kernel VM86 support, as they will all
1217 fall back to software emulation. Nevertheless, if you are using
1218 a 16-bit DOS program where 16-bit performance matters, vm86
1219 mode might be faster than emulation and you might want to
1222 Note that any app that works on a 64-bit kernel is unlikely to
1223 need this option, as 64-bit kernels don't, and can't, support
1224 V8086 mode. This option is also unrelated to 16-bit protected
1225 mode and is not needed to run most 16-bit programs under Wine.
1227 Enabling this option increases the complexity of the kernel
1228 and slows down exception handling a tiny bit.
1230 If unsure, say N here.
1234 default X86_LEGACY_VM86
1237 bool "Enable support for 16-bit segments" if EXPERT
1239 depends on MODIFY_LDT_SYSCALL
1241 This option is required by programs like Wine to run 16-bit
1242 protected mode legacy code on x86 processors. Disabling
1243 this option saves about 300 bytes on i386, or around 6K text
1244 plus 16K runtime memory on x86-64,
1248 depends on X86_16BIT && X86_32
1252 depends on X86_16BIT && X86_64
1254 config X86_VSYSCALL_EMULATION
1255 bool "Enable vsyscall emulation" if EXPERT
1259 This enables emulation of the legacy vsyscall page. Disabling
1260 it is roughly equivalent to booting with vsyscall=none, except
1261 that it will also disable the helpful warning if a program
1262 tries to use a vsyscall. With this option set to N, offending
1263 programs will just segfault, citing addresses of the form
1266 This option is required by many programs built before 2013, and
1267 care should be used even with newer programs if set to N.
1269 Disabling this option saves about 7K of kernel size and
1270 possibly 4K of additional runtime pagetable memory.
1272 config X86_IOPL_IOPERM
1273 bool "IOPERM and IOPL Emulation"
1276 This enables the ioperm() and iopl() syscalls which are necessary
1277 for legacy applications.
1279 Legacy IOPL support is an overbroad mechanism which allows user
1280 space aside of accessing all 65536 I/O ports also to disable
1281 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1282 capabilities and permission from potentially active security
1285 The emulation restricts the functionality of the syscall to
1286 only allowing the full range I/O port access, but prevents the
1287 ability to disable interrupts from user space which would be
1288 granted if the hardware IOPL mechanism would be used.
1291 tristate "Toshiba Laptop support"
1294 This adds a driver to safely access the System Management Mode of
1295 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1296 not work on models with a Phoenix BIOS. The System Management Mode
1297 is used to set the BIOS and power saving options on Toshiba portables.
1299 For information on utilities to make use of this driver see the
1300 Toshiba Linux utilities web site at:
1301 <http://www.buzzard.org.uk/toshiba/>.
1303 Say Y if you intend to run this kernel on a Toshiba portable.
1306 config X86_REBOOTFIXUPS
1307 bool "Enable X86 board specific fixups for reboot"
1310 This enables chipset and/or board specific fixups to be done
1311 in order to get reboot to work correctly. This is only needed on
1312 some combinations of hardware and BIOS. The symptom, for which
1313 this config is intended, is when reboot ends with a stalled/hung
1316 Currently, the only fixup is for the Geode machines using
1317 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1319 Say Y if you want to enable the fixup. Currently, it's safe to
1320 enable this option even if you don't need it.
1325 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1327 config MICROCODE_INITRD32
1329 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1331 config MICROCODE_LATE_LOADING
1332 bool "Late microcode loading (DANGEROUS)"
1334 depends on MICROCODE && SMP
1336 Loading microcode late, when the system is up and executing instructions
1337 is a tricky business and should be avoided if possible. Just the sequence
1338 of synchronizing all cores and SMT threads is one fragile dance which does
1339 not guarantee that cores might not softlock after the loading. Therefore,
1340 use this at your own risk. Late loading taints the kernel unless the
1341 microcode header indicates that it is safe for late loading via the
1342 minimal revision check. This minimal revision check can be enforced on
1343 the kernel command line with "microcode.minrev=Y".
1345 config MICROCODE_LATE_FORCE_MINREV
1346 bool "Enforce late microcode loading minimal revision check"
1348 depends on MICROCODE_LATE_LOADING
1350 To prevent that users load microcode late which modifies already
1351 in use features, newer microcode patches have a minimum revision field
1352 in the microcode header, which tells the kernel which minimum
1353 revision must be active in the CPU to safely load that new microcode
1354 late into the running system. If disabled the check will not
1355 be enforced but the kernel will be tainted when the minimal
1356 revision check fails.
1358 This minimal revision check can also be controlled via the
1359 "microcode.minrev" parameter on the kernel command line.
1364 tristate "/dev/cpu/*/msr - Model-specific register support"
1366 This device gives privileged processes access to the x86
1367 Model-Specific Registers (MSRs). It is a character device with
1368 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1369 MSR accesses are directed to a specific CPU on multi-processor
1373 tristate "/dev/cpu/*/cpuid - CPU information support"
1375 This device gives processes access to the x86 CPUID instruction to
1376 be executed on a specific processor. It is a character device
1377 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1381 prompt "High Memory Support"
1388 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1389 However, the address space of 32-bit x86 processors is only 4
1390 Gigabytes large. That means that, if you have a large amount of
1391 physical memory, not all of it can be "permanently mapped" by the
1392 kernel. The physical memory that's not permanently mapped is called
1395 If you are compiling a kernel which will never run on a machine with
1396 more than 1 Gigabyte total physical RAM, answer "off" here (default
1397 choice and suitable for most users). This will result in a "3GB/1GB"
1398 split: 3GB are mapped so that each process sees a 3GB virtual memory
1399 space and the remaining part of the 4GB virtual memory space is used
1400 by the kernel to permanently map as much physical memory as
1403 If the machine has between 1 and 4 Gigabytes physical RAM, then
1406 If more than 4 Gigabytes is used then answer "64GB" here. This
1407 selection turns Intel PAE (Physical Address Extension) mode on.
1408 PAE implements 3-level paging on IA32 processors. PAE is fully
1409 supported by Linux, PAE mode is implemented on all recent Intel
1410 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1411 then the kernel will not boot on CPUs that don't support PAE!
1413 The actual amount of total physical memory will either be
1414 auto detected or can be forced by using a kernel command line option
1415 such as "mem=256M". (Try "man bootparam" or see the documentation of
1416 your boot loader (lilo or loadlin) about how to pass options to the
1417 kernel at boot time.)
1419 If unsure, say "off".
1424 Select this if you have a 32-bit processor and between 1 and 4
1425 gigabytes of physical RAM.
1429 depends on X86_HAVE_PAE
1432 Select this if you have a 32-bit processor and more than 4
1433 gigabytes of physical RAM.
1438 prompt "Memory split" if EXPERT
1442 Select the desired split between kernel and user memory.
1444 If the address range available to the kernel is less than the
1445 physical memory installed, the remaining memory will be available
1446 as "high memory". Accessing high memory is a little more costly
1447 than low memory, as it needs to be mapped into the kernel first.
1448 Note that increasing the kernel address space limits the range
1449 available to user programs, making the address space there
1450 tighter. Selecting anything other than the default 3G/1G split
1451 will also likely make your kernel incompatible with binary-only
1454 If you are not absolutely sure what you are doing, leave this
1458 bool "3G/1G user/kernel split"
1459 config VMSPLIT_3G_OPT
1461 bool "3G/1G user/kernel split (for full 1G low memory)"
1463 bool "2G/2G user/kernel split"
1464 config VMSPLIT_2G_OPT
1466 bool "2G/2G user/kernel split (for full 2G low memory)"
1468 bool "1G/3G user/kernel split"
1473 default 0xB0000000 if VMSPLIT_3G_OPT
1474 default 0x80000000 if VMSPLIT_2G
1475 default 0x78000000 if VMSPLIT_2G_OPT
1476 default 0x40000000 if VMSPLIT_1G
1482 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1485 bool "PAE (Physical Address Extension) Support"
1486 depends on X86_32 && X86_HAVE_PAE
1487 select PHYS_ADDR_T_64BIT
1490 PAE is required for NX support, and furthermore enables
1491 larger swapspace support for non-overcommit purposes. It
1492 has the cost of more pagetable lookup overhead, and also
1493 consumes more pagetable space per process.
1496 bool "Enable 5-level page tables support"
1498 select DYNAMIC_MEMORY_LAYOUT
1499 select SPARSEMEM_VMEMMAP
1502 5-level paging enables access to larger address space:
1503 up to 128 PiB of virtual address space and 4 PiB of
1504 physical address space.
1506 It will be supported by future Intel CPUs.
1508 A kernel with the option enabled can be booted on machines that
1509 support 4- or 5-level paging.
1511 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1516 config X86_DIRECT_GBPAGES
1520 Certain kernel features effectively disable kernel
1521 linear 1 GB mappings (even if the CPU otherwise
1522 supports them), so don't confuse the user by printing
1523 that we have them enabled.
1525 config X86_CPA_STATISTICS
1526 bool "Enable statistic for Change Page Attribute"
1529 Expose statistics about the Change Page Attribute mechanism, which
1530 helps to determine the effectiveness of preserving large and huge
1531 page mappings when mapping protections are changed.
1533 config X86_MEM_ENCRYPT
1534 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1535 select DYNAMIC_PHYSICAL_MASK
1538 config AMD_MEM_ENCRYPT
1539 bool "AMD Secure Memory Encryption (SME) support"
1540 depends on X86_64 && CPU_SUP_AMD
1542 select DMA_COHERENT_POOL
1543 select ARCH_USE_MEMREMAP_PROT
1544 select INSTRUCTION_DECODER
1545 select ARCH_HAS_CC_PLATFORM
1546 select X86_MEM_ENCRYPT
1547 select UNACCEPTED_MEMORY
1549 Say yes to enable support for the encryption of system memory.
1550 This requires an AMD processor that supports Secure Memory
1553 # Common NUMA Features
1555 bool "NUMA Memory Allocation and Scheduler Support"
1557 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1558 default y if X86_BIGSMP
1559 select USE_PERCPU_NUMA_NODE_ID
1560 select OF_NUMA if OF
1562 Enable NUMA (Non-Uniform Memory Access) support.
1564 The kernel will try to allocate memory used by a CPU on the
1565 local memory controller of the CPU and add some more
1566 NUMA awareness to the kernel.
1568 For 64-bit this is recommended if the system is Intel Core i7
1569 (or later), AMD Opteron, or EM64T NUMA.
1571 For 32-bit this is only needed if you boot a 32-bit
1572 kernel on a 64-bit NUMA platform.
1574 Otherwise, you should say N.
1578 prompt "Old style AMD Opteron NUMA detection"
1579 depends on X86_64 && NUMA && PCI
1581 Enable AMD NUMA node topology detection. You should say Y here if
1582 you have a multi processor AMD system. This uses an old method to
1583 read the NUMA configuration directly from the builtin Northbridge
1584 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1585 which also takes priority if both are compiled in.
1587 config X86_64_ACPI_NUMA
1589 prompt "ACPI NUMA detection"
1590 depends on X86_64 && NUMA && ACPI && PCI
1593 Enable ACPI SRAT based node topology detection.
1596 bool "NUMA emulation"
1599 Enable NUMA emulation. A flat machine will be split
1600 into virtual nodes when booted with "numa=fake=N", where N is the
1601 number of nodes. This is only useful for debugging.
1604 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1606 default "10" if MAXSMP
1607 default "6" if X86_64
1611 Specify the maximum number of NUMA Nodes available on the target
1612 system. Increases memory reserved to accommodate various tables.
1614 config ARCH_FLATMEM_ENABLE
1616 depends on X86_32 && !NUMA
1618 config ARCH_SPARSEMEM_ENABLE
1620 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1621 select SPARSEMEM_STATIC if X86_32
1622 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1624 config ARCH_SPARSEMEM_DEFAULT
1625 def_bool X86_64 || (NUMA && X86_32)
1627 config ARCH_SELECT_MEMORY_MODEL
1629 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1631 config ARCH_MEMORY_PROBE
1632 bool "Enable sysfs memory/probe interface"
1633 depends on MEMORY_HOTPLUG
1635 This option enables a sysfs memory/probe interface for testing.
1636 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1637 If you are unsure how to answer this question, answer N.
1639 config ARCH_PROC_KCORE_TEXT
1641 depends on X86_64 && PROC_KCORE
1643 config ILLEGAL_POINTER_VALUE
1646 default 0xdead000000000000 if X86_64
1648 config X86_PMEM_LEGACY_DEVICE
1651 config X86_PMEM_LEGACY
1652 tristate "Support non-standard NVDIMMs and ADR protected memory"
1653 depends on PHYS_ADDR_T_64BIT
1655 select X86_PMEM_LEGACY_DEVICE
1656 select NUMA_KEEP_MEMINFO if NUMA
1659 Treat memory marked using the non-standard e820 type of 12 as used
1660 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1661 The kernel will offer these regions to the 'pmem' driver so
1662 they can be used for persistent storage.
1667 bool "Allocate 3rd-level pagetables from highmem"
1670 The VM uses one page table entry for each page of physical memory.
1671 For systems with a lot of RAM, this can be wasteful of precious
1672 low memory. Setting this option will put user-space page table
1673 entries in high memory.
1675 config X86_CHECK_BIOS_CORRUPTION
1676 bool "Check for low memory corruption"
1678 Periodically check for memory corruption in low memory, which
1679 is suspected to be caused by BIOS. Even when enabled in the
1680 configuration, it is disabled at runtime. Enable it by
1681 setting "memory_corruption_check=1" on the kernel command
1682 line. By default it scans the low 64k of memory every 60
1683 seconds; see the memory_corruption_check_size and
1684 memory_corruption_check_period parameters in
1685 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1687 When enabled with the default parameters, this option has
1688 almost no overhead, as it reserves a relatively small amount
1689 of memory and scans it infrequently. It both detects corruption
1690 and prevents it from affecting the running system.
1692 It is, however, intended as a diagnostic tool; if repeatable
1693 BIOS-originated corruption always affects the same memory,
1694 you can use memmap= to prevent the kernel from using that
1697 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1698 bool "Set the default setting of memory_corruption_check"
1699 depends on X86_CHECK_BIOS_CORRUPTION
1702 Set whether the default state of memory_corruption_check is
1705 config MATH_EMULATION
1707 depends on MODIFY_LDT_SYSCALL
1708 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1710 Linux can emulate a math coprocessor (used for floating point
1711 operations) if you don't have one. 486DX and Pentium processors have
1712 a math coprocessor built in, 486SX and 386 do not, unless you added
1713 a 487DX or 387, respectively. (The messages during boot time can
1714 give you some hints here ["man dmesg"].) Everyone needs either a
1715 coprocessor or this emulation.
1717 If you don't have a math coprocessor, you need to say Y here; if you
1718 say Y here even though you have a coprocessor, the coprocessor will
1719 be used nevertheless. (This behavior can be changed with the kernel
1720 command line option "no387", which comes handy if your coprocessor
1721 is broken. Try "man bootparam" or see the documentation of your boot
1722 loader (lilo or loadlin) about how to pass options to the kernel at
1723 boot time.) This means that it is a good idea to say Y here if you
1724 intend to use this kernel on different machines.
1726 More information about the internals of the Linux math coprocessor
1727 emulation can be found in <file:arch/x86/math-emu/README>.
1729 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1730 kernel, it won't hurt.
1734 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1736 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1737 the Memory Type Range Registers (MTRRs) may be used to control
1738 processor access to memory ranges. This is most useful if you have
1739 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1740 allows bus write transfers to be combined into a larger transfer
1741 before bursting over the PCI/AGP bus. This can increase performance
1742 of image write operations 2.5 times or more. Saying Y here creates a
1743 /proc/mtrr file which may be used to manipulate your processor's
1744 MTRRs. Typically the X server should use this.
1746 This code has a reasonably generic interface so that similar
1747 control registers on other processors can be easily supported
1750 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1751 Registers (ARRs) which provide a similar functionality to MTRRs. For
1752 these, the ARRs are used to emulate the MTRRs.
1753 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1754 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1755 write-combining. All of these processors are supported by this code
1756 and it makes sense to say Y here if you have one of them.
1758 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1759 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1760 can lead to all sorts of problems, so it's good to say Y here.
1762 You can safely say Y even if your machine doesn't have MTRRs, you'll
1763 just add about 9 KB to your kernel.
1765 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1767 config MTRR_SANITIZER
1769 prompt "MTRR cleanup support"
1772 Convert MTRR layout from continuous to discrete, so X drivers can
1773 add writeback entries.
1775 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1776 The largest mtrr entry size for a continuous block can be set with
1781 config MTRR_SANITIZER_ENABLE_DEFAULT
1782 int "MTRR cleanup enable value (0-1)"
1785 depends on MTRR_SANITIZER
1787 Enable mtrr cleanup default value
1789 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1790 int "MTRR cleanup spare reg num (0-7)"
1793 depends on MTRR_SANITIZER
1795 mtrr cleanup spare entries default, it can be changed via
1796 mtrr_spare_reg_nr=N on the kernel command line.
1800 prompt "x86 PAT support" if EXPERT
1803 Use PAT attributes to setup page level cache control.
1805 PATs are the modern equivalents of MTRRs and are much more
1806 flexible than MTRRs.
1808 Say N here if you see bootup problems (boot crash, boot hang,
1809 spontaneous reboots) or a non-working video driver.
1813 config ARCH_USES_PG_UNCACHED
1819 prompt "User Mode Instruction Prevention" if EXPERT
1821 User Mode Instruction Prevention (UMIP) is a security feature in
1822 some x86 processors. If enabled, a general protection fault is
1823 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1824 executed in user mode. These instructions unnecessarily expose
1825 information about the hardware state.
1827 The vast majority of applications do not use these instructions.
1828 For the very few that do, software emulation is provided in
1829 specific cases in protected and virtual-8086 modes. Emulated
1833 # GCC >= 9 and binutils >= 2.29
1834 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1836 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1837 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1838 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1839 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1845 CET features configured (Shadow stack or IBT)
1847 config X86_KERNEL_IBT
1848 prompt "Indirect Branch Tracking"
1850 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1851 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1852 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1856 Build the kernel with support for Indirect Branch Tracking, a
1857 hardware support course-grain forward-edge Control Flow Integrity
1858 protection. It enforces that all indirect calls must land on
1859 an ENDBR instruction, as such, the compiler will instrument the
1860 code with them to make this happen.
1862 In addition to building the kernel with IBT, seal all functions that
1863 are not indirect call targets, avoiding them ever becoming one.
1865 This requires LTO like objtool runs and will slow down the build. It
1866 does significantly reduce the number of ENDBR instructions in the
1869 config X86_INTEL_MEMORY_PROTECTION_KEYS
1870 prompt "Memory Protection Keys"
1872 # Note: only available in 64-bit mode
1873 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1874 select ARCH_USES_HIGH_VMA_FLAGS
1875 select ARCH_HAS_PKEYS
1877 Memory Protection Keys provides a mechanism for enforcing
1878 page-based protections, but without requiring modification of the
1879 page tables when an application changes protection domains.
1881 For details, see Documentation/core-api/protection-keys.rst
1886 prompt "TSX enable mode"
1887 depends on CPU_SUP_INTEL
1888 default X86_INTEL_TSX_MODE_OFF
1890 Intel's TSX (Transactional Synchronization Extensions) feature
1891 allows to optimize locking protocols through lock elision which
1892 can lead to a noticeable performance boost.
1894 On the other hand it has been shown that TSX can be exploited
1895 to form side channel attacks (e.g. TAA) and chances are there
1896 will be more of those attacks discovered in the future.
1898 Therefore TSX is not enabled by default (aka tsx=off). An admin
1899 might override this decision by tsx=on the command line parameter.
1900 Even with TSX enabled, the kernel will attempt to enable the best
1901 possible TAA mitigation setting depending on the microcode available
1902 for the particular machine.
1904 This option allows to set the default tsx mode between tsx=on, =off
1905 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1908 Say off if not sure, auto if TSX is in use but it should be used on safe
1909 platforms or on if TSX is in use and the security aspect of tsx is not
1912 config X86_INTEL_TSX_MODE_OFF
1915 TSX is disabled if possible - equals to tsx=off command line parameter.
1917 config X86_INTEL_TSX_MODE_ON
1920 TSX is always enabled on TSX capable HW - equals the tsx=on command
1923 config X86_INTEL_TSX_MODE_AUTO
1926 TSX is enabled on TSX capable HW that is believed to be safe against
1927 side channel attacks- equals the tsx=auto command line parameter.
1931 bool "Software Guard eXtensions (SGX)"
1932 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1934 depends on CRYPTO_SHA256=y
1936 select NUMA_KEEP_MEMINFO if NUMA
1939 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1940 that can be used by applications to set aside private regions of code
1941 and data, referred to as enclaves. An enclave's private memory can
1942 only be accessed by code running within the enclave. Accesses from
1943 outside the enclave, including other enclaves, are disallowed by
1948 config X86_USER_SHADOW_STACK
1949 bool "X86 userspace shadow stack"
1952 select ARCH_USES_HIGH_VMA_FLAGS
1955 Shadow stack protection is a hardware feature that detects function
1956 return address corruption. This helps mitigate ROP attacks.
1957 Applications must be enabled to use it, and old userspace does not
1958 get protection "for free".
1960 CPUs supporting shadow stacks were first released in 2020.
1962 See Documentation/arch/x86/shstk.rst for more information.
1966 config INTEL_TDX_HOST
1967 bool "Intel Trust Domain Extensions (TDX) host support"
1968 depends on CPU_SUP_INTEL
1970 depends on KVM_INTEL
1971 depends on X86_X2APIC
1972 select ARCH_KEEP_MEMBLOCK
1973 depends on CONTIG_ALLOC
1974 depends on !KEXEC_CORE
1977 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1978 host and certain physical attacks. This option enables necessary TDX
1979 support in the host kernel to run confidential VMs.
1984 bool "EFI runtime service support"
1987 select EFI_RUNTIME_WRAPPERS
1988 select ARCH_USE_MEMREMAP_PROT
1989 select EFI_RUNTIME_MAP if KEXEC_CORE
1991 This enables the kernel to use EFI runtime services that are
1992 available (such as the EFI variable services).
1994 This option is only useful on systems that have EFI firmware.
1995 In addition, you should use the latest ELILO loader available
1996 at <http://elilo.sourceforge.net> in order to take advantage
1997 of EFI runtime services. However, even with this option, the
1998 resultant kernel should continue to boot on existing non-EFI
2002 bool "EFI stub support"
2006 This kernel feature allows a bzImage to be loaded directly
2007 by EFI firmware without the use of a bootloader.
2009 See Documentation/admin-guide/efi-stub.rst for more information.
2011 config EFI_HANDOVER_PROTOCOL
2012 bool "EFI handover protocol (DEPRECATED)"
2016 Select this in order to include support for the deprecated EFI
2017 handover protocol, which defines alternative entry points into the
2018 EFI stub. This is a practice that has no basis in the UEFI
2019 specification, and requires a priori knowledge on the part of the
2020 bootloader about Linux/x86 specific ways of passing the command line
2021 and initrd, and where in memory those assets may be loaded.
2023 If in doubt, say Y. Even though the corresponding support is not
2024 present in upstream GRUB or other bootloaders, most distros build
2025 GRUB with numerous downstream patches applied, and may rely on the
2026 handover protocol as as result.
2029 bool "EFI mixed-mode support"
2030 depends on EFI_STUB && X86_64
2032 Enabling this feature allows a 64-bit kernel to be booted
2033 on a 32-bit firmware, provided that your CPU supports 64-bit
2036 Note that it is not possible to boot a mixed-mode enabled
2037 kernel via the EFI boot stub - a bootloader that supports
2038 the EFI handover protocol must be used.
2042 config EFI_FAKE_MEMMAP
2043 bool "Enable EFI fake memory map"
2046 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2047 this parameter, you can add arbitrary attribute to specific memory
2048 range by updating original (firmware provided) EFI memmap. This is
2049 useful for debugging of EFI memmap related feature, e.g., Address
2050 Range Mirroring feature.
2052 config EFI_MAX_FAKE_MEM
2053 int "maximum allowable number of ranges in efi_fake_mem boot option"
2054 depends on EFI_FAKE_MEMMAP
2058 Maximum allowable number of ranges in efi_fake_mem boot option.
2059 Ranges can be set up to this value using comma-separated list.
2060 The default value is 8.
2062 config EFI_RUNTIME_MAP
2063 bool "Export EFI runtime maps to sysfs" if EXPERT
2066 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2067 That memory map is required by the 2nd kernel to set up EFI virtual
2068 mappings after kexec, but can also be used for debugging purposes.
2070 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2072 source "kernel/Kconfig.hz"
2074 config ARCH_SUPPORTS_KEXEC
2077 config ARCH_SUPPORTS_KEXEC_FILE
2080 config ARCH_SELECTS_KEXEC_FILE
2082 depends on KEXEC_FILE
2083 select HAVE_IMA_KEXEC if IMA
2085 config ARCH_SUPPORTS_KEXEC_PURGATORY
2088 config ARCH_SUPPORTS_KEXEC_SIG
2091 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2094 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2097 config ARCH_SUPPORTS_KEXEC_JUMP
2100 config ARCH_SUPPORTS_CRASH_DUMP
2101 def_bool X86_64 || (X86_32 && HIGHMEM)
2103 config ARCH_SUPPORTS_CRASH_HOTPLUG
2106 config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2109 config PHYSICAL_START
2110 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2113 This gives the physical address where the kernel is loaded.
2115 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2116 will decompress itself to above physical address and run from there.
2117 Otherwise, bzImage will run from the address where it has been loaded
2118 by the boot loader. The only exception is if it is loaded below the
2119 above physical address, in which case it will relocate itself there.
2121 In normal kdump cases one does not have to set/change this option
2122 as now bzImage can be compiled as a completely relocatable image
2123 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2124 address. This option is mainly useful for the folks who don't want
2125 to use a bzImage for capturing the crash dump and want to use a
2126 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2127 to be specifically compiled to run from a specific memory area
2128 (normally a reserved region) and this option comes handy.
2130 So if you are using bzImage for capturing the crash dump,
2131 leave the value here unchanged to 0x1000000 and set
2132 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2133 for capturing the crash dump change this value to start of
2134 the reserved region. In other words, it can be set based on
2135 the "X" value as specified in the "crashkernel=YM@XM"
2136 command line boot parameter passed to the panic-ed
2137 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2138 for more details about crash dumps.
2140 Usage of bzImage for capturing the crash dump is recommended as
2141 one does not have to build two kernels. Same kernel can be used
2142 as production kernel and capture kernel. Above option should have
2143 gone away after relocatable bzImage support is introduced. But it
2144 is present because there are users out there who continue to use
2145 vmlinux for dump capture. This option should go away down the
2148 Don't change this unless you know what you are doing.
2151 bool "Build a relocatable kernel"
2154 This builds a kernel image that retains relocation information
2155 so it can be loaded someplace besides the default 1MB.
2156 The relocations tend to make the kernel binary about 10% larger,
2157 but are discarded at runtime.
2159 One use is for the kexec on panic case where the recovery kernel
2160 must live at a different physical address than the primary
2163 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2164 it has been loaded at and the compile time physical address
2165 (CONFIG_PHYSICAL_START) is used as the minimum location.
2167 config RANDOMIZE_BASE
2168 bool "Randomize the address of the kernel image (KASLR)"
2169 depends on RELOCATABLE
2172 In support of Kernel Address Space Layout Randomization (KASLR),
2173 this randomizes the physical address at which the kernel image
2174 is decompressed and the virtual address where the kernel
2175 image is mapped, as a security feature that deters exploit
2176 attempts relying on knowledge of the location of kernel
2179 On 64-bit, the kernel physical and virtual addresses are
2180 randomized separately. The physical address will be anywhere
2181 between 16MB and the top of physical memory (up to 64TB). The
2182 virtual address will be randomized from 16MB up to 1GB (9 bits
2183 of entropy). Note that this also reduces the memory space
2184 available to kernel modules from 1.5GB to 1GB.
2186 On 32-bit, the kernel physical and virtual addresses are
2187 randomized together. They will be randomized from 16MB up to
2188 512MB (8 bits of entropy).
2190 Entropy is generated using the RDRAND instruction if it is
2191 supported. If RDTSC is supported, its value is mixed into
2192 the entropy pool as well. If neither RDRAND nor RDTSC are
2193 supported, then entropy is read from the i8254 timer. The
2194 usable entropy is limited by the kernel being built using
2195 2GB addressing, and that PHYSICAL_ALIGN must be at a
2196 minimum of 2MB. As a result, only 10 bits of entropy are
2197 theoretically possible, but the implementations are further
2198 limited due to memory layouts.
2202 # Relocation on x86 needs some additional build support
2203 config X86_NEED_RELOCS
2205 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2207 config PHYSICAL_ALIGN
2208 hex "Alignment value to which kernel should be aligned"
2210 range 0x2000 0x1000000 if X86_32
2211 range 0x200000 0x1000000 if X86_64
2213 This value puts the alignment restrictions on physical address
2214 where kernel is loaded and run from. Kernel is compiled for an
2215 address which meets above alignment restriction.
2217 If bootloader loads the kernel at a non-aligned address and
2218 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2219 address aligned to above value and run from there.
2221 If bootloader loads the kernel at a non-aligned address and
2222 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2223 load address and decompress itself to the address it has been
2224 compiled for and run from there. The address for which kernel is
2225 compiled already meets above alignment restrictions. Hence the
2226 end result is that kernel runs from a physical address meeting
2227 above alignment restrictions.
2229 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2230 this value must be a multiple of 0x200000.
2232 Don't change this unless you know what you are doing.
2234 config DYNAMIC_MEMORY_LAYOUT
2237 This option makes base addresses of vmalloc and vmemmap as well as
2238 __PAGE_OFFSET movable during boot.
2240 config RANDOMIZE_MEMORY
2241 bool "Randomize the kernel memory sections"
2243 depends on RANDOMIZE_BASE
2244 select DYNAMIC_MEMORY_LAYOUT
2245 default RANDOMIZE_BASE
2247 Randomizes the base virtual address of kernel memory sections
2248 (physical memory mapping, vmalloc & vmemmap). This security feature
2249 makes exploits relying on predictable memory locations less reliable.
2251 The order of allocations remains unchanged. Entropy is generated in
2252 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2253 configuration have in average 30,000 different possible virtual
2254 addresses for each memory section.
2258 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2259 hex "Physical memory mapping padding" if EXPERT
2260 depends on RANDOMIZE_MEMORY
2261 default "0xa" if MEMORY_HOTPLUG
2263 range 0x1 0x40 if MEMORY_HOTPLUG
2266 Define the padding in terabytes added to the existing physical
2267 memory size during kernel memory randomization. It is useful
2268 for memory hotplug support but reduces the entropy available for
2269 address randomization.
2271 If unsure, leave at the default value.
2273 config ADDRESS_MASKING
2274 bool "Linear Address Masking support"
2277 Linear Address Masking (LAM) modifies the checking that is applied
2278 to 64-bit linear addresses, allowing software to use of the
2279 untranslated address bits for metadata.
2281 The capability can be used for efficient address sanitizers (ASAN)
2282 implementation and for optimizations in JITs.
2290 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2291 depends on COMPAT_32
2293 Certain buggy versions of glibc will crash if they are
2294 presented with a 32-bit vDSO that is not mapped at the address
2295 indicated in its segment table.
2297 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2298 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2299 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2300 the only released version with the bug, but OpenSUSE 9
2301 contains a buggy "glibc 2.3.2".
2303 The symptom of the bug is that everything crashes on startup, saying:
2304 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2306 Saying Y here changes the default value of the vdso32 boot
2307 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2308 This works around the glibc bug but hurts performance.
2310 If unsure, say N: if you are compiling your own kernel, you
2311 are unlikely to be using a buggy version of glibc.
2314 prompt "vsyscall table for legacy applications"
2316 default LEGACY_VSYSCALL_XONLY
2318 Legacy user code that does not know how to find the vDSO expects
2319 to be able to issue three syscalls by calling fixed addresses in
2320 kernel space. Since this location is not randomized with ASLR,
2321 it can be used to assist security vulnerability exploitation.
2323 This setting can be changed at boot time via the kernel command
2324 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2325 is deprecated and can only be enabled using the kernel command
2328 On a system with recent enough glibc (2.14 or newer) and no
2329 static binaries, you can say None without a performance penalty
2330 to improve security.
2332 If unsure, select "Emulate execution only".
2334 config LEGACY_VSYSCALL_XONLY
2335 bool "Emulate execution only"
2337 The kernel traps and emulates calls into the fixed vsyscall
2338 address mapping and does not allow reads. This
2339 configuration is recommended when userspace might use the
2340 legacy vsyscall area but support for legacy binary
2341 instrumentation of legacy code is not needed. It mitigates
2342 certain uses of the vsyscall area as an ASLR-bypassing
2345 config LEGACY_VSYSCALL_NONE
2348 There will be no vsyscall mapping at all. This will
2349 eliminate any risk of ASLR bypass due to the vsyscall
2350 fixed address mapping. Attempts to use the vsyscalls
2351 will be reported to dmesg, so that either old or
2352 malicious userspace programs can be identified.
2357 bool "Built-in kernel command line"
2359 Allow for specifying boot arguments to the kernel at
2360 build time. On some systems (e.g. embedded ones), it is
2361 necessary or convenient to provide some or all of the
2362 kernel boot arguments with the kernel itself (that is,
2363 to not rely on the boot loader to provide them.)
2365 To compile command line arguments into the kernel,
2366 set this option to 'Y', then fill in the
2367 boot arguments in CONFIG_CMDLINE.
2369 Systems with fully functional boot loaders (i.e. non-embedded)
2370 should leave this option set to 'N'.
2373 string "Built-in kernel command string"
2374 depends on CMDLINE_BOOL
2377 Enter arguments here that should be compiled into the kernel
2378 image and used at boot time. If the boot loader provides a
2379 command line at boot time, it is appended to this string to
2380 form the full kernel command line, when the system boots.
2382 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2383 change this behavior.
2385 In most cases, the command line (whether built-in or provided
2386 by the boot loader) should specify the device for the root
2389 config CMDLINE_OVERRIDE
2390 bool "Built-in command line overrides boot loader arguments"
2391 depends on CMDLINE_BOOL && CMDLINE != ""
2393 Set this option to 'Y' to have the kernel ignore the boot loader
2394 command line, and use ONLY the built-in command line.
2396 This is used to work around broken boot loaders. This should
2397 be set to 'N' under normal conditions.
2399 config MODIFY_LDT_SYSCALL
2400 bool "Enable the LDT (local descriptor table)" if EXPERT
2403 Linux can allow user programs to install a per-process x86
2404 Local Descriptor Table (LDT) using the modify_ldt(2) system
2405 call. This is required to run 16-bit or segmented code such as
2406 DOSEMU or some Wine programs. It is also used by some very old
2407 threading libraries.
2409 Enabling this feature adds a small amount of overhead to
2410 context switches and increases the low-level kernel attack
2411 surface. Disabling it removes the modify_ldt(2) system call.
2413 Saying 'N' here may make sense for embedded or server kernels.
2415 config STRICT_SIGALTSTACK_SIZE
2416 bool "Enforce strict size checking for sigaltstack"
2417 depends on DYNAMIC_SIGFRAME
2419 For historical reasons MINSIGSTKSZ is a constant which became
2420 already too small with AVX512 support. Add a mechanism to
2421 enforce strict checking of the sigaltstack size against the
2422 real size of the FPU frame. This option enables the check
2423 by default. It can also be controlled via the kernel command
2424 line option 'strict_sas_size' independent of this config
2425 switch. Enabling it might break existing applications which
2426 allocate a too small sigaltstack but 'work' because they
2427 never get a signal delivered.
2429 Say 'N' unless you want to really enforce this check.
2431 source "kernel/livepatch/Kconfig"
2435 config CC_HAS_NAMED_AS
2436 def_bool CC_IS_GCC && GCC_VERSION >= 120100
2438 config USE_X86_SEG_SUPPORT
2440 depends on CC_HAS_NAMED_AS
2442 # -fsanitize=kernel-address (KASAN) is at the moment incompatible
2443 # with named address spaces - see GCC PR sanitizer/111736.
2448 def_bool $(cc-option,-mharden-sls=all)
2450 config CC_HAS_RETURN_THUNK
2451 def_bool $(cc-option,-mfunction-return=thunk-extern)
2453 config CC_HAS_ENTRY_PADDING
2454 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2456 config FUNCTION_PADDING_CFI
2458 default 59 if FUNCTION_ALIGNMENT_64B
2459 default 27 if FUNCTION_ALIGNMENT_32B
2460 default 11 if FUNCTION_ALIGNMENT_16B
2461 default 3 if FUNCTION_ALIGNMENT_8B
2464 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2465 # except Kconfig can't do arithmetic :/
2466 config FUNCTION_PADDING_BYTES
2468 default FUNCTION_PADDING_CFI if CFI_CLANG
2469 default FUNCTION_ALIGNMENT
2473 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2474 select FUNCTION_ALIGNMENT_16B
2478 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2481 config HAVE_CALL_THUNKS
2483 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2489 config PREFIX_SYMBOLS
2491 depends on CALL_PADDING && !CFI_CLANG
2493 menuconfig SPECULATION_MITIGATIONS
2494 bool "Mitigations for speculative execution vulnerabilities"
2497 Say Y here to enable options which enable mitigations for
2498 speculative execution hardware vulnerabilities.
2500 If you say N, all mitigations will be disabled. You really
2501 should know what you are doing to say so.
2503 if SPECULATION_MITIGATIONS
2505 config MITIGATION_PAGE_TABLE_ISOLATION
2506 bool "Remove the kernel mapping in user mode"
2508 depends on (X86_64 || X86_PAE)
2510 This feature reduces the number of hardware side channels by
2511 ensuring that the majority of kernel addresses are not mapped
2514 See Documentation/arch/x86/pti.rst for more details.
2516 config MITIGATION_RETPOLINE
2517 bool "Avoid speculative indirect branches in kernel"
2518 select OBJTOOL if HAVE_OBJTOOL
2521 Compile kernel with the retpoline compiler options to guard against
2522 kernel-to-user data leaks by avoiding speculative indirect
2523 branches. Requires a compiler with -mindirect-branch=thunk-extern
2524 support for full protection. The kernel may run slower.
2526 config MITIGATION_RETHUNK
2527 bool "Enable return-thunks"
2528 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2529 select OBJTOOL if HAVE_OBJTOOL
2532 Compile the kernel with the return-thunks compiler option to guard
2533 against kernel-to-user data leaks by avoiding return speculation.
2534 Requires a compiler with -mfunction-return=thunk-extern
2535 support for full protection. The kernel may run slower.
2537 config MITIGATION_UNRET_ENTRY
2538 bool "Enable UNRET on kernel entry"
2539 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2542 Compile the kernel with support for the retbleed=unret mitigation.
2544 config MITIGATION_CALL_DEPTH_TRACKING
2545 bool "Mitigate RSB underflow with call depth tracking"
2546 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2547 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2551 Compile the kernel with call depth tracking to mitigate the Intel
2552 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2553 mitigation is off by default and needs to be enabled on the
2554 kernel command line via the retbleed=stuff option. For
2555 non-affected systems the overhead of this option is marginal as
2556 the call depth tracking is using run-time generated call thunks
2557 in a compiler generated padding area and call patching. This
2558 increases text size by ~5%. For non affected systems this space
2559 is unused. On affected SKL systems this results in a significant
2560 performance gain over the IBRS mitigation.
2562 config CALL_THUNKS_DEBUG
2563 bool "Enable call thunks and call depth tracking debugging"
2564 depends on MITIGATION_CALL_DEPTH_TRACKING
2565 select FUNCTION_ALIGNMENT_32B
2568 Enable call/ret counters for imbalance detection and build in
2569 a noisy dmesg about callthunks generation and call patching for
2570 trouble shooting. The debug prints need to be enabled on the
2571 kernel command line with 'debug-callthunks'.
2572 Only enable this when you are debugging call thunks as this
2573 creates a noticeable runtime overhead. If unsure say N.
2575 config MITIGATION_IBPB_ENTRY
2576 bool "Enable IBPB on kernel entry"
2577 depends on CPU_SUP_AMD && X86_64
2580 Compile the kernel with support for the retbleed=ibpb mitigation.
2582 config MITIGATION_IBRS_ENTRY
2583 bool "Enable IBRS on kernel entry"
2584 depends on CPU_SUP_INTEL && X86_64
2587 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2588 This mitigates both spectre_v2 and retbleed at great cost to
2591 config MITIGATION_SRSO
2592 bool "Mitigate speculative RAS overflow on AMD"
2593 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2596 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2598 config MITIGATION_SLS
2599 bool "Mitigate Straight-Line-Speculation"
2600 depends on CC_HAS_SLS && X86_64
2601 select OBJTOOL if HAVE_OBJTOOL
2604 Compile the kernel with straight-line-speculation options to guard
2605 against straight line speculation. The kernel image might be slightly
2608 config MITIGATION_GDS_FORCE
2609 bool "Force GDS Mitigation"
2610 depends on CPU_SUP_INTEL
2613 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2614 unprivileged speculative access to data which was previously stored in
2617 This option is equivalent to setting gather_data_sampling=force on the
2618 command line. The microcode mitigation is used if present, otherwise
2619 AVX is disabled as a mitigation. On affected systems that are missing
2620 the microcode any userspace code that unconditionally uses AVX will
2621 break with this option set.
2623 Setting this option on systems not vulnerable to GDS has no effect.
2627 config MITIGATION_RFDS
2628 bool "RFDS Mitigation"
2629 depends on CPU_SUP_INTEL
2632 Enable mitigation for Register File Data Sampling (RFDS) by default.
2633 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2634 allows unprivileged speculative access to stale data previously
2635 stored in floating point, vector and integer registers.
2636 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2640 config ARCH_HAS_ADD_PAGES
2642 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2644 menu "Power management and ACPI options"
2646 config ARCH_HIBERNATION_HEADER
2648 depends on HIBERNATION
2650 source "kernel/power/Kconfig"
2652 source "drivers/acpi/Kconfig"
2659 tristate "APM (Advanced Power Management) BIOS support"
2660 depends on X86_32 && PM_SLEEP
2662 APM is a BIOS specification for saving power using several different
2663 techniques. This is mostly useful for battery powered laptops with
2664 APM compliant BIOSes. If you say Y here, the system time will be
2665 reset after a RESUME operation, the /proc/apm device will provide
2666 battery status information, and user-space programs will receive
2667 notification of APM "events" (e.g. battery status change).
2669 If you select "Y" here, you can disable actual use of the APM
2670 BIOS by passing the "apm=off" option to the kernel at boot time.
2672 Note that the APM support is almost completely disabled for
2673 machines with more than one CPU.
2675 In order to use APM, you will need supporting software. For location
2676 and more information, read <file:Documentation/power/apm-acpi.rst>
2677 and the Battery Powered Linux mini-HOWTO, available from
2678 <http://www.tldp.org/docs.html#howto>.
2680 This driver does not spin down disk drives (see the hdparm(8)
2681 manpage ("man 8 hdparm") for that), and it doesn't turn off
2682 VESA-compliant "green" monitors.
2684 This driver does not support the TI 4000M TravelMate and the ACER
2685 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2686 desktop machines also don't have compliant BIOSes, and this driver
2687 may cause those machines to panic during the boot phase.
2689 Generally, if you don't have a battery in your machine, there isn't
2690 much point in using this driver and you should say N. If you get
2691 random kernel OOPSes or reboots that don't seem to be related to
2692 anything, try disabling/enabling this option (or disabling/enabling
2695 Some other things you should try when experiencing seemingly random,
2698 1) make sure that you have enough swap space and that it is
2700 2) pass the "idle=poll" option to the kernel
2701 3) switch on floating point emulation in the kernel and pass
2702 the "no387" option to the kernel
2703 4) pass the "floppy=nodma" option to the kernel
2704 5) pass the "mem=4M" option to the kernel (thereby disabling
2705 all but the first 4 MB of RAM)
2706 6) make sure that the CPU is not over clocked.
2707 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2708 8) disable the cache from your BIOS settings
2709 9) install a fan for the video card or exchange video RAM
2710 10) install a better fan for the CPU
2711 11) exchange RAM chips
2712 12) exchange the motherboard.
2714 To compile this driver as a module, choose M here: the
2715 module will be called apm.
2719 config APM_IGNORE_USER_SUSPEND
2720 bool "Ignore USER SUSPEND"
2722 This option will ignore USER SUSPEND requests. On machines with a
2723 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2724 series notebooks, it is necessary to say Y because of a BIOS bug.
2726 config APM_DO_ENABLE
2727 bool "Enable PM at boot time"
2729 Enable APM features at boot time. From page 36 of the APM BIOS
2730 specification: "When disabled, the APM BIOS does not automatically
2731 power manage devices, enter the Standby State, enter the Suspend
2732 State, or take power saving steps in response to CPU Idle calls."
2733 This driver will make CPU Idle calls when Linux is idle (unless this
2734 feature is turned off -- see "Do CPU IDLE calls", below). This
2735 should always save battery power, but more complicated APM features
2736 will be dependent on your BIOS implementation. You may need to turn
2737 this option off if your computer hangs at boot time when using APM
2738 support, or if it beeps continuously instead of suspending. Turn
2739 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2740 T400CDT. This is off by default since most machines do fine without
2745 bool "Make CPU Idle calls when idle"
2747 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2748 On some machines, this can activate improved power savings, such as
2749 a slowed CPU clock rate, when the machine is idle. These idle calls
2750 are made after the idle loop has run for some length of time (e.g.,
2751 333 mS). On some machines, this will cause a hang at boot time or
2752 whenever the CPU becomes idle. (On machines with more than one CPU,
2753 this option does nothing.)
2755 config APM_DISPLAY_BLANK
2756 bool "Enable console blanking using APM"
2758 Enable console blanking using the APM. Some laptops can use this to
2759 turn off the LCD backlight when the screen blanker of the Linux
2760 virtual console blanks the screen. Note that this is only used by
2761 the virtual console screen blanker, and won't turn off the backlight
2762 when using the X Window system. This also doesn't have anything to
2763 do with your VESA-compliant power-saving monitor. Further, this
2764 option doesn't work for all laptops -- it might not turn off your
2765 backlight at all, or it might print a lot of errors to the console,
2766 especially if you are using gpm.
2768 config APM_ALLOW_INTS
2769 bool "Allow interrupts during APM BIOS calls"
2771 Normally we disable external interrupts while we are making calls to
2772 the APM BIOS as a measure to lessen the effects of a badly behaving
2773 BIOS implementation. The BIOS should reenable interrupts if it
2774 needs to. Unfortunately, some BIOSes do not -- especially those in
2775 many of the newer IBM Thinkpads. If you experience hangs when you
2776 suspend, try setting this to Y. Otherwise, say N.
2780 source "drivers/cpufreq/Kconfig"
2782 source "drivers/cpuidle/Kconfig"
2784 source "drivers/idle/Kconfig"
2788 menu "Bus options (PCI etc.)"
2791 prompt "PCI access mode"
2792 depends on X86_32 && PCI
2795 On PCI systems, the BIOS can be used to detect the PCI devices and
2796 determine their configuration. However, some old PCI motherboards
2797 have BIOS bugs and may crash if this is done. Also, some embedded
2798 PCI-based systems don't have any BIOS at all. Linux can also try to
2799 detect the PCI hardware directly without using the BIOS.
2801 With this option, you can specify how Linux should detect the
2802 PCI devices. If you choose "BIOS", the BIOS will be used,
2803 if you choose "Direct", the BIOS won't be used, and if you
2804 choose "MMConfig", then PCI Express MMCONFIG will be used.
2805 If you choose "Any", the kernel will try MMCONFIG, then the
2806 direct access method and falls back to the BIOS if that doesn't
2807 work. If unsure, go with the default, which is "Any".
2812 config PCI_GOMMCONFIG
2829 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2831 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2834 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2837 bool "Support mmconfig PCI config space access" if X86_64
2839 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2840 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2844 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2848 depends on PCI && XEN
2850 config MMCONF_FAM10H
2852 depends on X86_64 && PCI_MMCONFIG && ACPI
2854 config PCI_CNB20LE_QUIRK
2855 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2858 Read the PCI windows out of the CNB20LE host bridge. This allows
2859 PCI hotplug to work on systems with the CNB20LE chipset which do
2862 There's no public spec for this chipset, and this functionality
2863 is known to be incomplete.
2865 You should say N unless you know you need this.
2868 bool "ISA bus support on modern systems" if EXPERT
2870 Expose ISA bus device drivers and options available for selection and
2871 configuration. Enable this option if your target machine has an ISA
2872 bus. ISA is an older system, displaced by PCI and newer bus
2873 architectures -- if your target machine is modern, it probably does
2874 not have an ISA bus.
2878 # x86_64 have no ISA slots, but can have ISA-style DMA.
2880 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2883 Enables ISA-style DMA support for devices requiring such controllers.
2891 Find out whether you have ISA slots on your motherboard. ISA is the
2892 name of a bus system, i.e. the way the CPU talks to the other stuff
2893 inside your box. Other bus systems are PCI, EISA, MicroChannel
2894 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2895 newer boards don't support it. If you have ISA, say Y, otherwise N.
2898 tristate "NatSemi SCx200 support"
2900 This provides basic support for National Semiconductor's
2901 (now AMD's) Geode processors. The driver probes for the
2902 PCI-IDs of several on-chip devices, so its a good dependency
2903 for other scx200_* drivers.
2905 If compiled as a module, the driver is named scx200.
2907 config SCx200HR_TIMER
2908 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2912 This driver provides a clocksource built upon the on-chip
2913 27MHz high-resolution timer. Its also a workaround for
2914 NSC Geode SC-1100's buggy TSC, which loses time when the
2915 processor goes idle (as is done by the scheduler). The
2916 other workaround is idle=poll boot option.
2919 bool "One Laptop Per Child support"
2927 Add support for detecting the unique features of the OLPC
2931 bool "OLPC XO-1 Power Management"
2932 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2934 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2937 bool "OLPC XO-1 Real Time Clock"
2938 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2940 Add support for the XO-1 real time clock, which can be used as a
2941 programmable wakeup source.
2944 bool "OLPC XO-1 SCI extras"
2945 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2949 Add support for SCI-based features of the OLPC XO-1 laptop:
2950 - EC-driven system wakeups
2954 - AC adapter status updates
2955 - Battery status updates
2957 config OLPC_XO15_SCI
2958 bool "OLPC XO-1.5 SCI extras"
2959 depends on OLPC && ACPI
2962 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2963 - EC-driven system wakeups
2964 - AC adapter status updates
2965 - Battery status updates
2968 bool "PCEngines ALIX System Support (LED setup)"
2971 This option enables system support for the PCEngines ALIX.
2972 At present this just sets up LEDs for GPIO control on
2973 ALIX2/3/6 boards. However, other system specific setup should
2976 Note: You must still enable the drivers for GPIO and LED support
2977 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2979 Note: You have to set alix.force=1 for boards with Award BIOS.
2982 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2985 This option enables system support for the Soekris Engineering net5501.
2988 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2992 This option enables system support for the Traverse Technologies GEOS.
2995 bool "Technologic Systems TS-5500 platform support"
2997 select CHECK_SIGNATURE
3001 This option enables system support for the Technologic Systems TS-5500.
3007 depends on CPU_SUP_AMD && PCI
3011 menu "Binary Emulations"
3013 config IA32_EMULATION
3014 bool "IA32 Emulation"
3016 select ARCH_WANT_OLD_COMPAT_IPC
3018 select COMPAT_OLD_SIGACTION
3020 Include code to run legacy 32-bit programs under a
3021 64-bit kernel. You should likely turn this on, unless you're
3022 100% sure that you don't have any 32-bit programs left.
3024 config IA32_EMULATION_DEFAULT_DISABLED
3025 bool "IA32 emulation disabled by default"
3027 depends on IA32_EMULATION
3029 Make IA32 emulation disabled by default. This prevents loading 32-bit
3030 processes and access to 32-bit syscalls. If unsure, leave it to its
3034 bool "x32 ABI for 64-bit mode"
3036 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3037 # compressed debug sections to x86_x32 properly:
3038 # https://github.com/ClangBuiltLinux/linux/issues/514
3039 # https://github.com/ClangBuiltLinux/linux/issues/1141
3040 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3042 Include code to run binaries for the x32 native 32-bit ABI
3043 for 64-bit processors. An x32 process gets access to the
3044 full 64-bit register file and wide data path while leaving
3045 pointers at 32 bits for smaller memory footprint.
3049 depends on IA32_EMULATION || X86_32
3051 select OLD_SIGSUSPEND3
3055 depends on IA32_EMULATION || X86_X32_ABI
3057 config COMPAT_FOR_U64_ALIGNMENT
3063 config HAVE_ATOMIC_IOMAP
3067 source "arch/x86/kvm/Kconfig"
3069 source "arch/x86/Kconfig.assembler"