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_CONFIGURES_CPU_MITIGATIONS
66 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
67 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
68 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
69 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
70 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
71 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
72 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
73 select ARCH_HAS_CACHE_LINE_SIZE
74 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
75 select ARCH_HAS_CPU_FINALIZE_INIT
76 select ARCH_HAS_CPU_PASID if IOMMU_SVA
77 select ARCH_HAS_CURRENT_STACK_POINTER
78 select ARCH_HAS_DEBUG_VIRTUAL
79 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
80 select ARCH_HAS_DEVMEM_IS_ALLOWED
81 select ARCH_HAS_EARLY_DEBUG if KGDB
82 select ARCH_HAS_ELF_RANDOMIZE
83 select ARCH_HAS_FAST_MULTIPLIER
84 select ARCH_HAS_FORTIFY_SOURCE
85 select ARCH_HAS_GCOV_PROFILE_ALL
86 select ARCH_HAS_KCOV if X86_64
87 select ARCH_HAS_MEM_ENCRYPT
88 select ARCH_HAS_MEMBARRIER_SYNC_CORE
89 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
90 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
91 select ARCH_HAS_PMEM_API if X86_64
92 select ARCH_HAS_PTE_DEVMAP if X86_64
93 select ARCH_HAS_PTE_SPECIAL
94 select ARCH_HAS_HW_PTE_YOUNG
95 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
96 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
97 select ARCH_HAS_COPY_MC if X86_64
98 select ARCH_HAS_SET_MEMORY
99 select ARCH_HAS_SET_DIRECT_MAP
100 select ARCH_HAS_STRICT_KERNEL_RWX
101 select ARCH_HAS_STRICT_MODULE_RWX
102 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
103 select ARCH_HAS_SYSCALL_WRAPPER
104 select ARCH_HAS_UBSAN
105 select ARCH_HAS_DEBUG_WX
106 select ARCH_HAS_ZONE_DMA_SET if EXPERT
107 select ARCH_HAVE_NMI_SAFE_CMPXCHG
108 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
109 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
110 select ARCH_MIGHT_HAVE_PC_PARPORT
111 select ARCH_MIGHT_HAVE_PC_SERIO
112 select ARCH_STACKWALK
113 select ARCH_SUPPORTS_ACPI
114 select ARCH_SUPPORTS_ATOMIC_RMW
115 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
116 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
117 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
118 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
119 select ARCH_SUPPORTS_CFI_CLANG if X86_64
120 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
121 select ARCH_SUPPORTS_LTO_CLANG
122 select ARCH_SUPPORTS_LTO_CLANG_THIN
123 select ARCH_USE_BUILTIN_BSWAP
124 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
125 select ARCH_USE_MEMTEST
126 select ARCH_USE_QUEUED_RWLOCKS
127 select ARCH_USE_QUEUED_SPINLOCKS
128 select ARCH_USE_SYM_ANNOTATIONS
129 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
130 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
131 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
132 select ARCH_WANTS_NO_INSTR
133 select ARCH_WANT_GENERAL_HUGETLB
134 select ARCH_WANT_HUGE_PMD_SHARE
135 select ARCH_WANT_LD_ORPHAN_WARN
136 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
137 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
138 select ARCH_WANTS_THP_SWAP if X86_64
139 select ARCH_HAS_PARANOID_L1D_FLUSH
140 select BUILDTIME_TABLE_SORT
142 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
143 select CLOCKSOURCE_WATCHDOG
144 # Word-size accesses may read uninitialized data past the trailing \0
145 # in strings and cause false KMSAN reports.
146 select DCACHE_WORD_ACCESS if !KMSAN
147 select DYNAMIC_SIGFRAME
148 select EDAC_ATOMIC_SCRUB
150 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
151 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST
152 select GENERIC_CLOCKEVENTS_MIN_ADJUST
153 select GENERIC_CMOS_UPDATE
154 select GENERIC_CPU_AUTOPROBE
155 select GENERIC_CPU_DEVICES
156 select GENERIC_CPU_VULNERABILITIES
157 select GENERIC_EARLY_IOREMAP
160 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
161 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
162 select GENERIC_IRQ_MIGRATION if SMP
163 select GENERIC_IRQ_PROBE
164 select GENERIC_IRQ_RESERVATION_MODE
165 select GENERIC_IRQ_SHOW
166 select GENERIC_PENDING_IRQ if SMP
167 select GENERIC_PTDUMP
168 select GENERIC_SMP_IDLE_THREAD
169 select GENERIC_TIME_VSYSCALL
170 select GENERIC_GETTIMEOFDAY
171 select GENERIC_VDSO_TIME_NS
172 select GUP_GET_PXX_LOW_HIGH if X86_PAE
173 select HARDIRQS_SW_RESEND
174 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
176 select HAVE_ACPI_APEI if ACPI
177 select HAVE_ACPI_APEI_NMI if ACPI
178 select HAVE_ALIGNED_STRUCT_PAGE
179 select HAVE_ARCH_AUDITSYSCALL
180 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
181 select HAVE_ARCH_HUGE_VMALLOC if X86_64
182 select HAVE_ARCH_JUMP_LABEL
183 select HAVE_ARCH_JUMP_LABEL_RELATIVE
184 select HAVE_ARCH_KASAN if X86_64
185 select HAVE_ARCH_KASAN_VMALLOC if X86_64
186 select HAVE_ARCH_KFENCE
187 select HAVE_ARCH_KMSAN if X86_64
188 select HAVE_ARCH_KGDB
189 select HAVE_ARCH_MMAP_RND_BITS if MMU
190 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
191 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
192 select HAVE_ARCH_PREL32_RELOCATIONS
193 select HAVE_ARCH_SECCOMP_FILTER
194 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
195 select HAVE_ARCH_STACKLEAK
196 select HAVE_ARCH_TRACEHOOK
197 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
198 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
199 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
200 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
201 select HAVE_ARCH_VMAP_STACK if X86_64
202 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
203 select HAVE_ARCH_WITHIN_STACK_FRAMES
204 select HAVE_ASM_MODVERSIONS
205 select HAVE_CMPXCHG_DOUBLE
206 select HAVE_CMPXCHG_LOCAL
207 select HAVE_CONTEXT_TRACKING_USER if X86_64
208 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
209 select HAVE_C_RECORDMCOUNT
210 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
211 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
212 select HAVE_BUILDTIME_MCOUNT_SORT
213 select HAVE_DEBUG_KMEMLEAK
214 select HAVE_DMA_CONTIGUOUS
215 select HAVE_DYNAMIC_FTRACE
216 select HAVE_DYNAMIC_FTRACE_WITH_REGS
217 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
218 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
219 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
220 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
222 select HAVE_EFFICIENT_UNALIGNED_ACCESS
224 select HAVE_EXIT_THREAD
226 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
227 select HAVE_FTRACE_MCOUNT_RECORD
228 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
229 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
230 select HAVE_FUNCTION_TRACER
231 select HAVE_GCC_PLUGINS
232 select HAVE_HW_BREAKPOINT
233 select HAVE_IOREMAP_PROT
234 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
235 select HAVE_IRQ_TIME_ACCOUNTING
236 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
237 select HAVE_KERNEL_BZIP2
238 select HAVE_KERNEL_GZIP
239 select HAVE_KERNEL_LZ4
240 select HAVE_KERNEL_LZMA
241 select HAVE_KERNEL_LZO
242 select HAVE_KERNEL_XZ
243 select HAVE_KERNEL_ZSTD
245 select HAVE_KPROBES_ON_FTRACE
246 select HAVE_FUNCTION_ERROR_INJECTION
247 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
476 config X86_CPU_RESCTRL
477 bool "x86 CPU resource control support"
478 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
480 select PROC_CPU_RESCTRL if PROC_FS
482 Enable x86 CPU resource control support.
484 Provide support for the allocation and monitoring of system resources
487 Intel calls this Intel Resource Director Technology
488 (Intel(R) RDT). More information about RDT can be found in the
489 Intel x86 Architecture Software Developer Manual.
491 AMD calls this AMD Platform Quality of Service (AMD QoS).
492 More information about AMD QoS can be found in the AMD64 Technology
493 Platform Quality of Service Extensions manual.
498 bool "Flexible Return and Event Delivery"
501 When enabled, try to use Flexible Return and Event Delivery
502 instead of the legacy SYSCALL/SYSENTER/IDT architecture for
503 ring transitions and exception/interrupt handling if the
507 bool "Support for big SMP systems with more than 8 CPUs"
508 depends on SMP && X86_32
510 This option is needed for the systems that have more than 8 CPUs.
512 config X86_EXTENDED_PLATFORM
513 bool "Support for extended (non-PC) x86 platforms"
516 If you disable this option then the kernel will only support
517 standard PC platforms. (which covers the vast majority of
520 If you enable this option then you'll be able to select support
521 for the following non-PC x86 platforms, depending on the value of
524 32-bit platforms (CONFIG_64BIT=n):
525 Goldfish (Android emulator)
528 SGI 320/540 (Visual Workstation)
529 STA2X11-based (e.g. Northville)
530 Moorestown MID devices
532 64-bit platforms (CONFIG_64BIT=y):
537 If you have one of these systems, or if you want to build a
538 generic distribution kernel, say Y here - otherwise say N.
540 # This is an alphabetically sorted list of 64 bit extended platforms
541 # Please maintain the alphabetic order if and when there are additions
543 bool "Numascale NumaChip"
545 depends on X86_EXTENDED_PLATFORM
548 depends on X86_X2APIC
549 depends on PCI_MMCONFIG
551 Adds support for Numascale NumaChip large-SMP systems. Needed to
552 enable more than ~168 cores.
553 If you don't have one of these, you should say N here.
557 select HYPERVISOR_GUEST
559 depends on X86_64 && PCI
560 depends on X86_EXTENDED_PLATFORM
563 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
564 supposed to run on these EM64T-based machines. Only choose this option
565 if you have one of these machines.
568 bool "SGI Ultraviolet"
570 depends on X86_EXTENDED_PLATFORM
573 depends on KEXEC_CORE
574 depends on X86_X2APIC
577 This option is needed in order to support SGI Ultraviolet systems.
578 If you don't have one of these, you should say N here.
580 # Following is an alphabetically sorted list of 32 bit extended platforms
581 # Please maintain the alphabetic order if and when there are additions
584 bool "Goldfish (Virtual Platform)"
585 depends on X86_EXTENDED_PLATFORM
587 Enable support for the Goldfish virtual platform used primarily
588 for Android development. Unless you are building for the Android
589 Goldfish emulator say N here.
592 bool "CE4100 TV platform"
594 depends on PCI_GODIRECT
595 depends on X86_IO_APIC
597 depends on X86_EXTENDED_PLATFORM
598 select X86_REBOOTFIXUPS
600 select OF_EARLY_FLATTREE
602 Select for the Intel CE media processor (CE4100) SOC.
603 This option compiles in support for the CE4100 SOC for settop
604 boxes and media devices.
607 bool "Intel MID platform support"
608 depends on X86_EXTENDED_PLATFORM
609 depends on X86_PLATFORM_DEVICES
611 depends on X86_64 || (PCI_GOANY && X86_32)
612 depends on X86_IO_APIC
617 Select to build a kernel capable of supporting Intel MID (Mobile
618 Internet Device) platform systems which do not have the PCI legacy
619 interfaces. If you are building for a PC class system say N here.
621 Intel MID platforms are based on an Intel processor and chipset which
622 consume less power than most of the x86 derivatives.
624 config X86_INTEL_QUARK
625 bool "Intel Quark platform support"
627 depends on X86_EXTENDED_PLATFORM
628 depends on X86_PLATFORM_DEVICES
632 depends on X86_IO_APIC
637 Select to include support for Quark X1000 SoC.
638 Say Y here if you have a Quark based system such as the Arduino
639 compatible Intel Galileo.
641 config X86_INTEL_LPSS
642 bool "Intel Low Power Subsystem Support"
643 depends on X86 && ACPI && PCI
648 Select to build support for Intel Low Power Subsystem such as
649 found on Intel Lynxpoint PCH. Selecting this option enables
650 things like clock tree (common clock framework) and pincontrol
651 which are needed by the LPSS peripheral drivers.
653 config X86_AMD_PLATFORM_DEVICE
654 bool "AMD ACPI2Platform devices support"
659 Select to interpret AMD specific ACPI device to platform device
660 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
661 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
662 implemented under PINCTRL subsystem.
665 tristate "Intel SoC IOSF Sideband support for SoC platforms"
668 This option enables sideband register access support for Intel SoC
669 platforms. On these platforms the IOSF sideband is used in lieu of
670 MSR's for some register accesses, mostly but not limited to thermal
671 and power. Drivers may query the availability of this device to
672 determine if they need the sideband in order to work on these
673 platforms. The sideband is available on the following SoC products.
674 This list is not meant to be exclusive.
679 You should say Y if you are running a kernel on one of these SoC's.
681 config IOSF_MBI_DEBUG
682 bool "Enable IOSF sideband access through debugfs"
683 depends on IOSF_MBI && DEBUG_FS
685 Select this option to expose the IOSF sideband access registers (MCR,
686 MDR, MCRX) through debugfs to write and read register information from
687 different units on the SoC. This is most useful for obtaining device
688 state information for debug and analysis. As this is a general access
689 mechanism, users of this option would have specific knowledge of the
690 device they want to access.
692 If you don't require the option or are in doubt, say N.
695 bool "RDC R-321x SoC"
697 depends on X86_EXTENDED_PLATFORM
699 select X86_REBOOTFIXUPS
701 This option is needed for RDC R-321x system-on-chip, also known
703 If you don't have one of these chips, you should say N here.
705 config X86_32_NON_STANDARD
706 bool "Support non-standard 32-bit SMP architectures"
707 depends on X86_32 && SMP
708 depends on X86_EXTENDED_PLATFORM
710 This option compiles in the bigsmp and STA2X11 default
711 subarchitectures. It is intended for a generic binary
712 kernel. If you select them all, kernel will probe it one by
713 one and will fallback to default.
715 # Alphabetically sorted list of Non standard 32 bit platforms
717 config X86_SUPPORTS_MEMORY_FAILURE
719 # MCE code calls memory_failure():
721 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
722 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
723 depends on X86_64 || !SPARSEMEM
724 select ARCH_SUPPORTS_MEMORY_FAILURE
727 bool "STA2X11 Companion Chip Support"
728 depends on X86_32_NON_STANDARD && PCI
733 This adds support for boards based on the STA2X11 IO-Hub,
734 a.k.a. "ConneXt". The chip is used in place of the standard
735 PC chipset, so all "standard" peripherals are missing. If this
736 option is selected the kernel will still be able to boot on
737 standard PC machines.
740 tristate "Eurobraille/Iris poweroff module"
743 The Iris machines from EuroBraille do not have APM or ACPI support
744 to shut themselves down properly. A special I/O sequence is
745 needed to do so, which is what this module does at
748 This is only for Iris machines from EuroBraille.
752 config SCHED_OMIT_FRAME_POINTER
754 prompt "Single-depth WCHAN output"
757 Calculate simpler /proc/<PID>/wchan values. If this option
758 is disabled then wchan values will recurse back to the
759 caller function. This provides more accurate wchan values,
760 at the expense of slightly more scheduling overhead.
762 If in doubt, say "Y".
764 menuconfig HYPERVISOR_GUEST
765 bool "Linux guest support"
767 Say Y here to enable options for running Linux under various hyper-
768 visors. This option enables basic hypervisor detection and platform
771 If you say N, all options in this submenu will be skipped and
772 disabled, and Linux guest support won't be built in.
777 bool "Enable paravirtualization code"
778 depends on HAVE_STATIC_CALL
780 This changes the kernel so it can modify itself when it is run
781 under a hypervisor, potentially improving performance significantly
782 over full virtualization. However, when run without a hypervisor
783 the kernel is theoretically slower and slightly larger.
788 config PARAVIRT_DEBUG
789 bool "paravirt-ops debugging"
790 depends on PARAVIRT && DEBUG_KERNEL
792 Enable to debug paravirt_ops internals. Specifically, BUG if
793 a paravirt_op is missing when it is called.
795 config PARAVIRT_SPINLOCKS
796 bool "Paravirtualization layer for spinlocks"
797 depends on PARAVIRT && SMP
799 Paravirtualized spinlocks allow a pvops backend to replace the
800 spinlock implementation with something virtualization-friendly
801 (for example, block the virtual CPU rather than spinning).
803 It has a minimal impact on native kernels and gives a nice performance
804 benefit on paravirtualized KVM / Xen kernels.
806 If you are unsure how to answer this question, answer Y.
808 config X86_HV_CALLBACK_VECTOR
811 source "arch/x86/xen/Kconfig"
814 bool "KVM Guest support (including kvmclock)"
816 select PARAVIRT_CLOCK
817 select ARCH_CPUIDLE_HALTPOLL
818 select X86_HV_CALLBACK_VECTOR
821 This option enables various optimizations for running under the KVM
822 hypervisor. It includes a paravirtualized clock, so that instead
823 of relying on a PIT (or probably other) emulation by the
824 underlying device model, the host provides the guest with
825 timing infrastructure such as time of day, and system time
827 config ARCH_CPUIDLE_HALTPOLL
829 prompt "Disable host haltpoll when loading haltpoll driver"
831 If virtualized under KVM, disable host haltpoll.
834 bool "Support for running PVH guests"
836 This option enables the PVH entry point for guest virtual machines
837 as specified in the x86/HVM direct boot ABI.
839 config PARAVIRT_TIME_ACCOUNTING
840 bool "Paravirtual steal time accounting"
843 Select this option to enable fine granularity task steal time
844 accounting. Time spent executing other tasks in parallel with
845 the current vCPU is discounted from the vCPU power. To account for
846 that, there can be a small performance impact.
848 If in doubt, say N here.
850 config PARAVIRT_CLOCK
853 config JAILHOUSE_GUEST
854 bool "Jailhouse non-root cell support"
855 depends on X86_64 && PCI
858 This option allows to run Linux as guest in a Jailhouse non-root
859 cell. You can leave this option disabled if you only want to start
860 Jailhouse and run Linux afterwards in the root cell.
863 bool "ACRN Guest support"
865 select X86_HV_CALLBACK_VECTOR
867 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
868 a flexible, lightweight reference open-source hypervisor, built with
869 real-time and safety-criticality in mind. It is built for embedded
870 IOT with small footprint and real-time features. More details can be
871 found in https://projectacrn.org/.
873 config INTEL_TDX_GUEST
874 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
875 depends on X86_64 && CPU_SUP_INTEL
876 depends on X86_X2APIC
878 select ARCH_HAS_CC_PLATFORM
879 select X86_MEM_ENCRYPT
881 select UNACCEPTED_MEMORY
883 Support running as a guest under Intel TDX. Without this support,
884 the guest kernel can not boot or run under TDX.
885 TDX includes memory encryption and integrity capabilities
886 which protect the confidentiality and integrity of guest
887 memory contents and CPU state. TDX guests are protected from
888 some attacks from the VMM.
890 endif # HYPERVISOR_GUEST
892 source "arch/x86/Kconfig.cpu"
896 prompt "HPET Timer Support" if X86_32
898 Use the IA-PC HPET (High Precision Event Timer) to manage
899 time in preference to the PIT and RTC, if a HPET is
901 HPET is the next generation timer replacing legacy 8254s.
902 The HPET provides a stable time base on SMP
903 systems, unlike the TSC, but it is more expensive to access,
904 as it is off-chip. The interface used is documented
905 in the HPET spec, revision 1.
907 You can safely choose Y here. However, HPET will only be
908 activated if the platform and the BIOS support this feature.
909 Otherwise the 8254 will be used for timing services.
911 Choose N to continue using the legacy 8254 timer.
913 config HPET_EMULATE_RTC
915 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
917 # Mark as expert because too many people got it wrong.
918 # The code disables itself when not needed.
921 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
922 bool "Enable DMI scanning" if EXPERT
924 Enabled scanning of DMI to identify machine quirks. Say Y
925 here unless you have verified that your setup is not
926 affected by entries in the DMI blacklist. Required by PNP
930 bool "Old AMD GART IOMMU support"
934 depends on X86_64 && PCI && AMD_NB
936 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
937 GART based hardware IOMMUs.
939 The GART supports full DMA access for devices with 32-bit access
940 limitations, on systems with more than 3 GB. This is usually needed
941 for USB, sound, many IDE/SATA chipsets and some other devices.
943 Newer systems typically have a modern AMD IOMMU, supported via
944 the CONFIG_AMD_IOMMU=y config option.
946 In normal configurations this driver is only active when needed:
947 there's more than 3 GB of memory and the system contains a
948 32-bit limited device.
952 config BOOT_VESA_SUPPORT
955 If true, at least one selected framebuffer driver can take advantage
956 of VESA video modes set at an early boot stage via the vga= parameter.
959 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
960 depends on X86_64 && SMP && DEBUG_KERNEL
961 select CPUMASK_OFFSTACK
963 Enable maximum number of CPUS and NUMA Nodes for this architecture.
967 # The maximum number of CPUs supported:
969 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
970 # and which can be configured interactively in the
971 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
973 # The ranges are different on 32-bit and 64-bit kernels, depending on
974 # hardware capabilities and scalability features of the kernel.
976 # ( If MAXSMP is enabled we just use the highest possible value and disable
977 # interactive configuration. )
980 config NR_CPUS_RANGE_BEGIN
982 default NR_CPUS_RANGE_END if MAXSMP
986 config NR_CPUS_RANGE_END
989 default 64 if SMP && X86_BIGSMP
990 default 8 if SMP && !X86_BIGSMP
993 config NR_CPUS_RANGE_END
996 default 8192 if SMP && CPUMASK_OFFSTACK
997 default 512 if SMP && !CPUMASK_OFFSTACK
1000 config NR_CPUS_DEFAULT
1003 default 32 if X86_BIGSMP
1007 config NR_CPUS_DEFAULT
1010 default 8192 if MAXSMP
1015 int "Maximum number of CPUs" if SMP && !MAXSMP
1016 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1017 default NR_CPUS_DEFAULT
1019 This allows you to specify the maximum number of CPUs which this
1020 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1021 supported value is 8192, otherwise the maximum value is 512. The
1022 minimum value which makes sense is 2.
1024 This is purely to save memory: each supported CPU adds about 8KB
1025 to the kernel image.
1027 config SCHED_CLUSTER
1028 bool "Cluster scheduler support"
1032 Cluster scheduler support improves the CPU scheduler's decision
1033 making when dealing with machines that have clusters of CPUs.
1034 Cluster usually means a couple of CPUs which are placed closely
1035 by sharing mid-level caches, last-level cache tags or internal
1043 prompt "Multi-core scheduler support"
1046 Multi-core scheduler support improves the CPU scheduler's decision
1047 making when dealing with multi-core CPU chips at a cost of slightly
1048 increased overhead in some places. If unsure say N here.
1050 config SCHED_MC_PRIO
1051 bool "CPU core priorities scheduler support"
1053 select X86_INTEL_PSTATE if CPU_SUP_INTEL
1054 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
1058 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1059 core ordering determined at manufacturing time, which allows
1060 certain cores to reach higher turbo frequencies (when running
1061 single threaded workloads) than others.
1063 Enabling this kernel feature teaches the scheduler about
1064 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1065 scheduler's CPU selection logic accordingly, so that higher
1066 overall system performance can be achieved.
1068 This feature will have no effect on CPUs without this feature.
1070 If unsure say Y here.
1074 depends on !SMP && X86_LOCAL_APIC
1077 bool "Local APIC support on uniprocessors" if !PCI_MSI
1079 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1081 A local APIC (Advanced Programmable Interrupt Controller) is an
1082 integrated interrupt controller in the CPU. If you have a single-CPU
1083 system which has a processor with a local APIC, you can say Y here to
1084 enable and use it. If you say Y here even though your machine doesn't
1085 have a local APIC, then the kernel will still run with no slowdown at
1086 all. The local APIC supports CPU-generated self-interrupts (timer,
1087 performance counters), and the NMI watchdog which detects hard
1090 config X86_UP_IOAPIC
1091 bool "IO-APIC support on uniprocessors"
1092 depends on X86_UP_APIC
1094 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1095 SMP-capable replacement for PC-style interrupt controllers. Most
1096 SMP systems and many recent uniprocessor systems have one.
1098 If you have a single-CPU system with an IO-APIC, you can say Y here
1099 to use it. If you say Y here even though your machine doesn't have
1100 an IO-APIC, then the kernel will still run with no slowdown at all.
1102 config X86_LOCAL_APIC
1104 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1105 select IRQ_DOMAIN_HIERARCHY
1109 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1111 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1112 bool "Reroute for broken boot IRQs"
1113 depends on X86_IO_APIC
1115 This option enables a workaround that fixes a source of
1116 spurious interrupts. This is recommended when threaded
1117 interrupt handling is used on systems where the generation of
1118 superfluous "boot interrupts" cannot be disabled.
1120 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1121 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1122 kernel does during interrupt handling). On chipsets where this
1123 boot IRQ generation cannot be disabled, this workaround keeps
1124 the original IRQ line masked so that only the equivalent "boot
1125 IRQ" is delivered to the CPUs. The workaround also tells the
1126 kernel to set up the IRQ handler on the boot IRQ line. In this
1127 way only one interrupt is delivered to the kernel. Otherwise
1128 the spurious second interrupt may cause the kernel to bring
1129 down (vital) interrupt lines.
1131 Only affects "broken" chipsets. Interrupt sharing may be
1132 increased on these systems.
1135 bool "Machine Check / overheating reporting"
1136 select GENERIC_ALLOCATOR
1139 Machine Check support allows the processor to notify the
1140 kernel if it detects a problem (e.g. overheating, data corruption).
1141 The action the kernel takes depends on the severity of the problem,
1142 ranging from warning messages to halting the machine.
1144 config X86_MCELOG_LEGACY
1145 bool "Support for deprecated /dev/mcelog character device"
1148 Enable support for /dev/mcelog which is needed by the old mcelog
1149 userspace logging daemon. Consider switching to the new generation
1152 config X86_MCE_INTEL
1154 prompt "Intel MCE features"
1155 depends on X86_MCE && X86_LOCAL_APIC
1157 Additional support for intel specific MCE features such as
1158 the thermal monitor.
1162 prompt "AMD MCE features"
1163 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1165 Additional support for AMD specific MCE features such as
1166 the DRAM Error Threshold.
1168 config X86_ANCIENT_MCE
1169 bool "Support for old Pentium 5 / WinChip machine checks"
1170 depends on X86_32 && X86_MCE
1172 Include support for machine check handling on old Pentium 5 or WinChip
1173 systems. These typically need to be enabled explicitly on the command
1176 config X86_MCE_THRESHOLD
1177 depends on X86_MCE_AMD || X86_MCE_INTEL
1180 config X86_MCE_INJECT
1181 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1182 tristate "Machine check injector support"
1184 Provide support for injecting machine checks for testing purposes.
1185 If you don't know what a machine check is and you don't do kernel
1186 QA it is safe to say n.
1188 source "arch/x86/events/Kconfig"
1190 config X86_LEGACY_VM86
1191 bool "Legacy VM86 support"
1194 This option allows user programs to put the CPU into V8086
1195 mode, which is an 80286-era approximation of 16-bit real mode.
1197 Some very old versions of X and/or vbetool require this option
1198 for user mode setting. Similarly, DOSEMU will use it if
1199 available to accelerate real mode DOS programs. However, any
1200 recent version of DOSEMU, X, or vbetool should be fully
1201 functional even without kernel VM86 support, as they will all
1202 fall back to software emulation. Nevertheless, if you are using
1203 a 16-bit DOS program where 16-bit performance matters, vm86
1204 mode might be faster than emulation and you might want to
1207 Note that any app that works on a 64-bit kernel is unlikely to
1208 need this option, as 64-bit kernels don't, and can't, support
1209 V8086 mode. This option is also unrelated to 16-bit protected
1210 mode and is not needed to run most 16-bit programs under Wine.
1212 Enabling this option increases the complexity of the kernel
1213 and slows down exception handling a tiny bit.
1215 If unsure, say N here.
1219 default X86_LEGACY_VM86
1222 bool "Enable support for 16-bit segments" if EXPERT
1224 depends on MODIFY_LDT_SYSCALL
1226 This option is required by programs like Wine to run 16-bit
1227 protected mode legacy code on x86 processors. Disabling
1228 this option saves about 300 bytes on i386, or around 6K text
1229 plus 16K runtime memory on x86-64,
1233 depends on X86_16BIT && X86_32
1237 depends on X86_16BIT && X86_64
1239 config X86_VSYSCALL_EMULATION
1240 bool "Enable vsyscall emulation" if EXPERT
1244 This enables emulation of the legacy vsyscall page. Disabling
1245 it is roughly equivalent to booting with vsyscall=none, except
1246 that it will also disable the helpful warning if a program
1247 tries to use a vsyscall. With this option set to N, offending
1248 programs will just segfault, citing addresses of the form
1251 This option is required by many programs built before 2013, and
1252 care should be used even with newer programs if set to N.
1254 Disabling this option saves about 7K of kernel size and
1255 possibly 4K of additional runtime pagetable memory.
1257 config X86_IOPL_IOPERM
1258 bool "IOPERM and IOPL Emulation"
1261 This enables the ioperm() and iopl() syscalls which are necessary
1262 for legacy applications.
1264 Legacy IOPL support is an overbroad mechanism which allows user
1265 space aside of accessing all 65536 I/O ports also to disable
1266 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1267 capabilities and permission from potentially active security
1270 The emulation restricts the functionality of the syscall to
1271 only allowing the full range I/O port access, but prevents the
1272 ability to disable interrupts from user space which would be
1273 granted if the hardware IOPL mechanism would be used.
1276 tristate "Toshiba Laptop support"
1279 This adds a driver to safely access the System Management Mode of
1280 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1281 not work on models with a Phoenix BIOS. The System Management Mode
1282 is used to set the BIOS and power saving options on Toshiba portables.
1284 For information on utilities to make use of this driver see the
1285 Toshiba Linux utilities web site at:
1286 <http://www.buzzard.org.uk/toshiba/>.
1288 Say Y if you intend to run this kernel on a Toshiba portable.
1291 config X86_REBOOTFIXUPS
1292 bool "Enable X86 board specific fixups for reboot"
1295 This enables chipset and/or board specific fixups to be done
1296 in order to get reboot to work correctly. This is only needed on
1297 some combinations of hardware and BIOS. The symptom, for which
1298 this config is intended, is when reboot ends with a stalled/hung
1301 Currently, the only fixup is for the Geode machines using
1302 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1304 Say Y if you want to enable the fixup. Currently, it's safe to
1305 enable this option even if you don't need it.
1310 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1312 config MICROCODE_INITRD32
1314 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1316 config MICROCODE_LATE_LOADING
1317 bool "Late microcode loading (DANGEROUS)"
1319 depends on MICROCODE && SMP
1321 Loading microcode late, when the system is up and executing instructions
1322 is a tricky business and should be avoided if possible. Just the sequence
1323 of synchronizing all cores and SMT threads is one fragile dance which does
1324 not guarantee that cores might not softlock after the loading. Therefore,
1325 use this at your own risk. Late loading taints the kernel unless the
1326 microcode header indicates that it is safe for late loading via the
1327 minimal revision check. This minimal revision check can be enforced on
1328 the kernel command line with "microcode.minrev=Y".
1330 config MICROCODE_LATE_FORCE_MINREV
1331 bool "Enforce late microcode loading minimal revision check"
1333 depends on MICROCODE_LATE_LOADING
1335 To prevent that users load microcode late which modifies already
1336 in use features, newer microcode patches have a minimum revision field
1337 in the microcode header, which tells the kernel which minimum
1338 revision must be active in the CPU to safely load that new microcode
1339 late into the running system. If disabled the check will not
1340 be enforced but the kernel will be tainted when the minimal
1341 revision check fails.
1343 This minimal revision check can also be controlled via the
1344 "microcode.minrev" parameter on the kernel command line.
1349 tristate "/dev/cpu/*/msr - Model-specific register support"
1351 This device gives privileged processes access to the x86
1352 Model-Specific Registers (MSRs). It is a character device with
1353 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1354 MSR accesses are directed to a specific CPU on multi-processor
1358 tristate "/dev/cpu/*/cpuid - CPU information support"
1360 This device gives processes access to the x86 CPUID instruction to
1361 be executed on a specific processor. It is a character device
1362 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1366 prompt "High Memory Support"
1373 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1374 However, the address space of 32-bit x86 processors is only 4
1375 Gigabytes large. That means that, if you have a large amount of
1376 physical memory, not all of it can be "permanently mapped" by the
1377 kernel. The physical memory that's not permanently mapped is called
1380 If you are compiling a kernel which will never run on a machine with
1381 more than 1 Gigabyte total physical RAM, answer "off" here (default
1382 choice and suitable for most users). This will result in a "3GB/1GB"
1383 split: 3GB are mapped so that each process sees a 3GB virtual memory
1384 space and the remaining part of the 4GB virtual memory space is used
1385 by the kernel to permanently map as much physical memory as
1388 If the machine has between 1 and 4 Gigabytes physical RAM, then
1391 If more than 4 Gigabytes is used then answer "64GB" here. This
1392 selection turns Intel PAE (Physical Address Extension) mode on.
1393 PAE implements 3-level paging on IA32 processors. PAE is fully
1394 supported by Linux, PAE mode is implemented on all recent Intel
1395 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1396 then the kernel will not boot on CPUs that don't support PAE!
1398 The actual amount of total physical memory will either be
1399 auto detected or can be forced by using a kernel command line option
1400 such as "mem=256M". (Try "man bootparam" or see the documentation of
1401 your boot loader (lilo or loadlin) about how to pass options to the
1402 kernel at boot time.)
1404 If unsure, say "off".
1409 Select this if you have a 32-bit processor and between 1 and 4
1410 gigabytes of physical RAM.
1414 depends on X86_HAVE_PAE
1417 Select this if you have a 32-bit processor and more than 4
1418 gigabytes of physical RAM.
1423 prompt "Memory split" if EXPERT
1427 Select the desired split between kernel and user memory.
1429 If the address range available to the kernel is less than the
1430 physical memory installed, the remaining memory will be available
1431 as "high memory". Accessing high memory is a little more costly
1432 than low memory, as it needs to be mapped into the kernel first.
1433 Note that increasing the kernel address space limits the range
1434 available to user programs, making the address space there
1435 tighter. Selecting anything other than the default 3G/1G split
1436 will also likely make your kernel incompatible with binary-only
1439 If you are not absolutely sure what you are doing, leave this
1443 bool "3G/1G user/kernel split"
1444 config VMSPLIT_3G_OPT
1446 bool "3G/1G user/kernel split (for full 1G low memory)"
1448 bool "2G/2G user/kernel split"
1449 config VMSPLIT_2G_OPT
1451 bool "2G/2G user/kernel split (for full 2G low memory)"
1453 bool "1G/3G user/kernel split"
1458 default 0xB0000000 if VMSPLIT_3G_OPT
1459 default 0x80000000 if VMSPLIT_2G
1460 default 0x78000000 if VMSPLIT_2G_OPT
1461 default 0x40000000 if VMSPLIT_1G
1467 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1470 bool "PAE (Physical Address Extension) Support"
1471 depends on X86_32 && X86_HAVE_PAE
1472 select PHYS_ADDR_T_64BIT
1475 PAE is required for NX support, and furthermore enables
1476 larger swapspace support for non-overcommit purposes. It
1477 has the cost of more pagetable lookup overhead, and also
1478 consumes more pagetable space per process.
1481 bool "Enable 5-level page tables support"
1483 select DYNAMIC_MEMORY_LAYOUT
1484 select SPARSEMEM_VMEMMAP
1487 5-level paging enables access to larger address space:
1488 up to 128 PiB of virtual address space and 4 PiB of
1489 physical address space.
1491 It will be supported by future Intel CPUs.
1493 A kernel with the option enabled can be booted on machines that
1494 support 4- or 5-level paging.
1496 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1501 config X86_DIRECT_GBPAGES
1505 Certain kernel features effectively disable kernel
1506 linear 1 GB mappings (even if the CPU otherwise
1507 supports them), so don't confuse the user by printing
1508 that we have them enabled.
1510 config X86_CPA_STATISTICS
1511 bool "Enable statistic for Change Page Attribute"
1514 Expose statistics about the Change Page Attribute mechanism, which
1515 helps to determine the effectiveness of preserving large and huge
1516 page mappings when mapping protections are changed.
1518 config X86_MEM_ENCRYPT
1519 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1520 select DYNAMIC_PHYSICAL_MASK
1523 config AMD_MEM_ENCRYPT
1524 bool "AMD Secure Memory Encryption (SME) support"
1525 depends on X86_64 && CPU_SUP_AMD
1527 select DMA_COHERENT_POOL
1528 select ARCH_USE_MEMREMAP_PROT
1529 select INSTRUCTION_DECODER
1530 select ARCH_HAS_CC_PLATFORM
1531 select X86_MEM_ENCRYPT
1532 select UNACCEPTED_MEMORY
1534 Say yes to enable support for the encryption of system memory.
1535 This requires an AMD processor that supports Secure Memory
1538 # Common NUMA Features
1540 bool "NUMA Memory Allocation and Scheduler Support"
1542 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1543 default y if X86_BIGSMP
1544 select USE_PERCPU_NUMA_NODE_ID
1545 select OF_NUMA if OF
1547 Enable NUMA (Non-Uniform Memory Access) support.
1549 The kernel will try to allocate memory used by a CPU on the
1550 local memory controller of the CPU and add some more
1551 NUMA awareness to the kernel.
1553 For 64-bit this is recommended if the system is Intel Core i7
1554 (or later), AMD Opteron, or EM64T NUMA.
1556 For 32-bit this is only needed if you boot a 32-bit
1557 kernel on a 64-bit NUMA platform.
1559 Otherwise, you should say N.
1563 prompt "Old style AMD Opteron NUMA detection"
1564 depends on X86_64 && NUMA && PCI
1566 Enable AMD NUMA node topology detection. You should say Y here if
1567 you have a multi processor AMD system. This uses an old method to
1568 read the NUMA configuration directly from the builtin Northbridge
1569 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1570 which also takes priority if both are compiled in.
1572 config X86_64_ACPI_NUMA
1574 prompt "ACPI NUMA detection"
1575 depends on X86_64 && NUMA && ACPI && PCI
1578 Enable ACPI SRAT based node topology detection.
1581 bool "NUMA emulation"
1584 Enable NUMA emulation. A flat machine will be split
1585 into virtual nodes when booted with "numa=fake=N", where N is the
1586 number of nodes. This is only useful for debugging.
1589 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1591 default "10" if MAXSMP
1592 default "6" if X86_64
1596 Specify the maximum number of NUMA Nodes available on the target
1597 system. Increases memory reserved to accommodate various tables.
1599 config ARCH_FLATMEM_ENABLE
1601 depends on X86_32 && !NUMA
1603 config ARCH_SPARSEMEM_ENABLE
1605 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1606 select SPARSEMEM_STATIC if X86_32
1607 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1609 config ARCH_SPARSEMEM_DEFAULT
1610 def_bool X86_64 || (NUMA && X86_32)
1612 config ARCH_SELECT_MEMORY_MODEL
1614 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1616 config ARCH_MEMORY_PROBE
1617 bool "Enable sysfs memory/probe interface"
1618 depends on MEMORY_HOTPLUG
1620 This option enables a sysfs memory/probe interface for testing.
1621 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1622 If you are unsure how to answer this question, answer N.
1624 config ARCH_PROC_KCORE_TEXT
1626 depends on X86_64 && PROC_KCORE
1628 config ILLEGAL_POINTER_VALUE
1631 default 0xdead000000000000 if X86_64
1633 config X86_PMEM_LEGACY_DEVICE
1636 config X86_PMEM_LEGACY
1637 tristate "Support non-standard NVDIMMs and ADR protected memory"
1638 depends on PHYS_ADDR_T_64BIT
1640 select X86_PMEM_LEGACY_DEVICE
1641 select NUMA_KEEP_MEMINFO if NUMA
1644 Treat memory marked using the non-standard e820 type of 12 as used
1645 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1646 The kernel will offer these regions to the 'pmem' driver so
1647 they can be used for persistent storage.
1652 bool "Allocate 3rd-level pagetables from highmem"
1655 The VM uses one page table entry for each page of physical memory.
1656 For systems with a lot of RAM, this can be wasteful of precious
1657 low memory. Setting this option will put user-space page table
1658 entries in high memory.
1660 config X86_CHECK_BIOS_CORRUPTION
1661 bool "Check for low memory corruption"
1663 Periodically check for memory corruption in low memory, which
1664 is suspected to be caused by BIOS. Even when enabled in the
1665 configuration, it is disabled at runtime. Enable it by
1666 setting "memory_corruption_check=1" on the kernel command
1667 line. By default it scans the low 64k of memory every 60
1668 seconds; see the memory_corruption_check_size and
1669 memory_corruption_check_period parameters in
1670 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1672 When enabled with the default parameters, this option has
1673 almost no overhead, as it reserves a relatively small amount
1674 of memory and scans it infrequently. It both detects corruption
1675 and prevents it from affecting the running system.
1677 It is, however, intended as a diagnostic tool; if repeatable
1678 BIOS-originated corruption always affects the same memory,
1679 you can use memmap= to prevent the kernel from using that
1682 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1683 bool "Set the default setting of memory_corruption_check"
1684 depends on X86_CHECK_BIOS_CORRUPTION
1687 Set whether the default state of memory_corruption_check is
1690 config MATH_EMULATION
1692 depends on MODIFY_LDT_SYSCALL
1693 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1695 Linux can emulate a math coprocessor (used for floating point
1696 operations) if you don't have one. 486DX and Pentium processors have
1697 a math coprocessor built in, 486SX and 386 do not, unless you added
1698 a 487DX or 387, respectively. (The messages during boot time can
1699 give you some hints here ["man dmesg"].) Everyone needs either a
1700 coprocessor or this emulation.
1702 If you don't have a math coprocessor, you need to say Y here; if you
1703 say Y here even though you have a coprocessor, the coprocessor will
1704 be used nevertheless. (This behavior can be changed with the kernel
1705 command line option "no387", which comes handy if your coprocessor
1706 is broken. Try "man bootparam" or see the documentation of your boot
1707 loader (lilo or loadlin) about how to pass options to the kernel at
1708 boot time.) This means that it is a good idea to say Y here if you
1709 intend to use this kernel on different machines.
1711 More information about the internals of the Linux math coprocessor
1712 emulation can be found in <file:arch/x86/math-emu/README>.
1714 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1715 kernel, it won't hurt.
1719 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1721 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1722 the Memory Type Range Registers (MTRRs) may be used to control
1723 processor access to memory ranges. This is most useful if you have
1724 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1725 allows bus write transfers to be combined into a larger transfer
1726 before bursting over the PCI/AGP bus. This can increase performance
1727 of image write operations 2.5 times or more. Saying Y here creates a
1728 /proc/mtrr file which may be used to manipulate your processor's
1729 MTRRs. Typically the X server should use this.
1731 This code has a reasonably generic interface so that similar
1732 control registers on other processors can be easily supported
1735 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1736 Registers (ARRs) which provide a similar functionality to MTRRs. For
1737 these, the ARRs are used to emulate the MTRRs.
1738 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1739 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1740 write-combining. All of these processors are supported by this code
1741 and it makes sense to say Y here if you have one of them.
1743 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1744 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1745 can lead to all sorts of problems, so it's good to say Y here.
1747 You can safely say Y even if your machine doesn't have MTRRs, you'll
1748 just add about 9 KB to your kernel.
1750 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1752 config MTRR_SANITIZER
1754 prompt "MTRR cleanup support"
1757 Convert MTRR layout from continuous to discrete, so X drivers can
1758 add writeback entries.
1760 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1761 The largest mtrr entry size for a continuous block can be set with
1766 config MTRR_SANITIZER_ENABLE_DEFAULT
1767 int "MTRR cleanup enable value (0-1)"
1770 depends on MTRR_SANITIZER
1772 Enable mtrr cleanup default value
1774 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1775 int "MTRR cleanup spare reg num (0-7)"
1778 depends on MTRR_SANITIZER
1780 mtrr cleanup spare entries default, it can be changed via
1781 mtrr_spare_reg_nr=N on the kernel command line.
1785 prompt "x86 PAT support" if EXPERT
1788 Use PAT attributes to setup page level cache control.
1790 PATs are the modern equivalents of MTRRs and are much more
1791 flexible than MTRRs.
1793 Say N here if you see bootup problems (boot crash, boot hang,
1794 spontaneous reboots) or a non-working video driver.
1798 config ARCH_USES_PG_UNCACHED
1804 prompt "User Mode Instruction Prevention" if EXPERT
1806 User Mode Instruction Prevention (UMIP) is a security feature in
1807 some x86 processors. If enabled, a general protection fault is
1808 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1809 executed in user mode. These instructions unnecessarily expose
1810 information about the hardware state.
1812 The vast majority of applications do not use these instructions.
1813 For the very few that do, software emulation is provided in
1814 specific cases in protected and virtual-8086 modes. Emulated
1818 # GCC >= 9 and binutils >= 2.29
1819 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1821 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1822 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1823 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1824 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1830 CET features configured (Shadow stack or IBT)
1832 config X86_KERNEL_IBT
1833 prompt "Indirect Branch Tracking"
1835 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1836 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1837 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1841 Build the kernel with support for Indirect Branch Tracking, a
1842 hardware support course-grain forward-edge Control Flow Integrity
1843 protection. It enforces that all indirect calls must land on
1844 an ENDBR instruction, as such, the compiler will instrument the
1845 code with them to make this happen.
1847 In addition to building the kernel with IBT, seal all functions that
1848 are not indirect call targets, avoiding them ever becoming one.
1850 This requires LTO like objtool runs and will slow down the build. It
1851 does significantly reduce the number of ENDBR instructions in the
1854 config X86_INTEL_MEMORY_PROTECTION_KEYS
1855 prompt "Memory Protection Keys"
1857 # Note: only available in 64-bit mode
1858 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1859 select ARCH_USES_HIGH_VMA_FLAGS
1860 select ARCH_HAS_PKEYS
1862 Memory Protection Keys provides a mechanism for enforcing
1863 page-based protections, but without requiring modification of the
1864 page tables when an application changes protection domains.
1866 For details, see Documentation/core-api/protection-keys.rst
1871 prompt "TSX enable mode"
1872 depends on CPU_SUP_INTEL
1873 default X86_INTEL_TSX_MODE_OFF
1875 Intel's TSX (Transactional Synchronization Extensions) feature
1876 allows to optimize locking protocols through lock elision which
1877 can lead to a noticeable performance boost.
1879 On the other hand it has been shown that TSX can be exploited
1880 to form side channel attacks (e.g. TAA) and chances are there
1881 will be more of those attacks discovered in the future.
1883 Therefore TSX is not enabled by default (aka tsx=off). An admin
1884 might override this decision by tsx=on the command line parameter.
1885 Even with TSX enabled, the kernel will attempt to enable the best
1886 possible TAA mitigation setting depending on the microcode available
1887 for the particular machine.
1889 This option allows to set the default tsx mode between tsx=on, =off
1890 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1893 Say off if not sure, auto if TSX is in use but it should be used on safe
1894 platforms or on if TSX is in use and the security aspect of tsx is not
1897 config X86_INTEL_TSX_MODE_OFF
1900 TSX is disabled if possible - equals to tsx=off command line parameter.
1902 config X86_INTEL_TSX_MODE_ON
1905 TSX is always enabled on TSX capable HW - equals the tsx=on command
1908 config X86_INTEL_TSX_MODE_AUTO
1911 TSX is enabled on TSX capable HW that is believed to be safe against
1912 side channel attacks- equals the tsx=auto command line parameter.
1916 bool "Software Guard eXtensions (SGX)"
1917 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1919 depends on CRYPTO_SHA256=y
1921 select NUMA_KEEP_MEMINFO if NUMA
1924 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1925 that can be used by applications to set aside private regions of code
1926 and data, referred to as enclaves. An enclave's private memory can
1927 only be accessed by code running within the enclave. Accesses from
1928 outside the enclave, including other enclaves, are disallowed by
1933 config X86_USER_SHADOW_STACK
1934 bool "X86 userspace shadow stack"
1937 select ARCH_USES_HIGH_VMA_FLAGS
1940 Shadow stack protection is a hardware feature that detects function
1941 return address corruption. This helps mitigate ROP attacks.
1942 Applications must be enabled to use it, and old userspace does not
1943 get protection "for free".
1945 CPUs supporting shadow stacks were first released in 2020.
1947 See Documentation/arch/x86/shstk.rst for more information.
1951 config INTEL_TDX_HOST
1952 bool "Intel Trust Domain Extensions (TDX) host support"
1953 depends on CPU_SUP_INTEL
1955 depends on KVM_INTEL
1956 depends on X86_X2APIC
1957 select ARCH_KEEP_MEMBLOCK
1958 depends on CONTIG_ALLOC
1959 depends on !KEXEC_CORE
1962 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1963 host and certain physical attacks. This option enables necessary TDX
1964 support in the host kernel to run confidential VMs.
1969 bool "EFI runtime service support"
1972 select EFI_RUNTIME_WRAPPERS
1973 select ARCH_USE_MEMREMAP_PROT
1974 select EFI_RUNTIME_MAP if KEXEC_CORE
1976 This enables the kernel to use EFI runtime services that are
1977 available (such as the EFI variable services).
1979 This option is only useful on systems that have EFI firmware.
1980 In addition, you should use the latest ELILO loader available
1981 at <http://elilo.sourceforge.net> in order to take advantage
1982 of EFI runtime services. However, even with this option, the
1983 resultant kernel should continue to boot on existing non-EFI
1987 bool "EFI stub support"
1991 This kernel feature allows a bzImage to be loaded directly
1992 by EFI firmware without the use of a bootloader.
1994 See Documentation/admin-guide/efi-stub.rst for more information.
1996 config EFI_HANDOVER_PROTOCOL
1997 bool "EFI handover protocol (DEPRECATED)"
2001 Select this in order to include support for the deprecated EFI
2002 handover protocol, which defines alternative entry points into the
2003 EFI stub. This is a practice that has no basis in the UEFI
2004 specification, and requires a priori knowledge on the part of the
2005 bootloader about Linux/x86 specific ways of passing the command line
2006 and initrd, and where in memory those assets may be loaded.
2008 If in doubt, say Y. Even though the corresponding support is not
2009 present in upstream GRUB or other bootloaders, most distros build
2010 GRUB with numerous downstream patches applied, and may rely on the
2011 handover protocol as as result.
2014 bool "EFI mixed-mode support"
2015 depends on EFI_STUB && X86_64
2017 Enabling this feature allows a 64-bit kernel to be booted
2018 on a 32-bit firmware, provided that your CPU supports 64-bit
2021 Note that it is not possible to boot a mixed-mode enabled
2022 kernel via the EFI boot stub - a bootloader that supports
2023 the EFI handover protocol must be used.
2027 config EFI_FAKE_MEMMAP
2028 bool "Enable EFI fake memory map"
2031 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2032 this parameter, you can add arbitrary attribute to specific memory
2033 range by updating original (firmware provided) EFI memmap. This is
2034 useful for debugging of EFI memmap related feature, e.g., Address
2035 Range Mirroring feature.
2037 config EFI_MAX_FAKE_MEM
2038 int "maximum allowable number of ranges in efi_fake_mem boot option"
2039 depends on EFI_FAKE_MEMMAP
2043 Maximum allowable number of ranges in efi_fake_mem boot option.
2044 Ranges can be set up to this value using comma-separated list.
2045 The default value is 8.
2047 config EFI_RUNTIME_MAP
2048 bool "Export EFI runtime maps to sysfs" if EXPERT
2051 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2052 That memory map is required by the 2nd kernel to set up EFI virtual
2053 mappings after kexec, but can also be used for debugging purposes.
2055 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2057 source "kernel/Kconfig.hz"
2059 config ARCH_SUPPORTS_KEXEC
2062 config ARCH_SUPPORTS_KEXEC_FILE
2065 config ARCH_SELECTS_KEXEC_FILE
2067 depends on KEXEC_FILE
2068 select HAVE_IMA_KEXEC if IMA
2070 config ARCH_SUPPORTS_KEXEC_PURGATORY
2073 config ARCH_SUPPORTS_KEXEC_SIG
2076 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2079 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2082 config ARCH_SUPPORTS_KEXEC_JUMP
2085 config ARCH_SUPPORTS_CRASH_DUMP
2086 def_bool X86_64 || (X86_32 && HIGHMEM)
2088 config ARCH_SUPPORTS_CRASH_HOTPLUG
2091 config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2092 def_bool CRASH_RESERVE
2094 config PHYSICAL_START
2095 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2098 This gives the physical address where the kernel is loaded.
2100 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2101 will decompress itself to above physical address and run from there.
2102 Otherwise, bzImage will run from the address where it has been loaded
2103 by the boot loader. The only exception is if it is loaded below the
2104 above physical address, in which case it will relocate itself there.
2106 In normal kdump cases one does not have to set/change this option
2107 as now bzImage can be compiled as a completely relocatable image
2108 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2109 address. This option is mainly useful for the folks who don't want
2110 to use a bzImage for capturing the crash dump and want to use a
2111 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2112 to be specifically compiled to run from a specific memory area
2113 (normally a reserved region) and this option comes handy.
2115 So if you are using bzImage for capturing the crash dump,
2116 leave the value here unchanged to 0x1000000 and set
2117 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2118 for capturing the crash dump change this value to start of
2119 the reserved region. In other words, it can be set based on
2120 the "X" value as specified in the "crashkernel=YM@XM"
2121 command line boot parameter passed to the panic-ed
2122 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2123 for more details about crash dumps.
2125 Usage of bzImage for capturing the crash dump is recommended as
2126 one does not have to build two kernels. Same kernel can be used
2127 as production kernel and capture kernel. Above option should have
2128 gone away after relocatable bzImage support is introduced. But it
2129 is present because there are users out there who continue to use
2130 vmlinux for dump capture. This option should go away down the
2133 Don't change this unless you know what you are doing.
2136 bool "Build a relocatable kernel"
2139 This builds a kernel image that retains relocation information
2140 so it can be loaded someplace besides the default 1MB.
2141 The relocations tend to make the kernel binary about 10% larger,
2142 but are discarded at runtime.
2144 One use is for the kexec on panic case where the recovery kernel
2145 must live at a different physical address than the primary
2148 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2149 it has been loaded at and the compile time physical address
2150 (CONFIG_PHYSICAL_START) is used as the minimum location.
2152 config RANDOMIZE_BASE
2153 bool "Randomize the address of the kernel image (KASLR)"
2154 depends on RELOCATABLE
2157 In support of Kernel Address Space Layout Randomization (KASLR),
2158 this randomizes the physical address at which the kernel image
2159 is decompressed and the virtual address where the kernel
2160 image is mapped, as a security feature that deters exploit
2161 attempts relying on knowledge of the location of kernel
2164 On 64-bit, the kernel physical and virtual addresses are
2165 randomized separately. The physical address will be anywhere
2166 between 16MB and the top of physical memory (up to 64TB). The
2167 virtual address will be randomized from 16MB up to 1GB (9 bits
2168 of entropy). Note that this also reduces the memory space
2169 available to kernel modules from 1.5GB to 1GB.
2171 On 32-bit, the kernel physical and virtual addresses are
2172 randomized together. They will be randomized from 16MB up to
2173 512MB (8 bits of entropy).
2175 Entropy is generated using the RDRAND instruction if it is
2176 supported. If RDTSC is supported, its value is mixed into
2177 the entropy pool as well. If neither RDRAND nor RDTSC are
2178 supported, then entropy is read from the i8254 timer. The
2179 usable entropy is limited by the kernel being built using
2180 2GB addressing, and that PHYSICAL_ALIGN must be at a
2181 minimum of 2MB. As a result, only 10 bits of entropy are
2182 theoretically possible, but the implementations are further
2183 limited due to memory layouts.
2187 # Relocation on x86 needs some additional build support
2188 config X86_NEED_RELOCS
2190 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2192 config PHYSICAL_ALIGN
2193 hex "Alignment value to which kernel should be aligned"
2195 range 0x2000 0x1000000 if X86_32
2196 range 0x200000 0x1000000 if X86_64
2198 This value puts the alignment restrictions on physical address
2199 where kernel is loaded and run from. Kernel is compiled for an
2200 address which meets above alignment restriction.
2202 If bootloader loads the kernel at a non-aligned address and
2203 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2204 address aligned to above value and run from there.
2206 If bootloader loads the kernel at a non-aligned address and
2207 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2208 load address and decompress itself to the address it has been
2209 compiled for and run from there. The address for which kernel is
2210 compiled already meets above alignment restrictions. Hence the
2211 end result is that kernel runs from a physical address meeting
2212 above alignment restrictions.
2214 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2215 this value must be a multiple of 0x200000.
2217 Don't change this unless you know what you are doing.
2219 config DYNAMIC_MEMORY_LAYOUT
2222 This option makes base addresses of vmalloc and vmemmap as well as
2223 __PAGE_OFFSET movable during boot.
2225 config RANDOMIZE_MEMORY
2226 bool "Randomize the kernel memory sections"
2228 depends on RANDOMIZE_BASE
2229 select DYNAMIC_MEMORY_LAYOUT
2230 default RANDOMIZE_BASE
2232 Randomizes the base virtual address of kernel memory sections
2233 (physical memory mapping, vmalloc & vmemmap). This security feature
2234 makes exploits relying on predictable memory locations less reliable.
2236 The order of allocations remains unchanged. Entropy is generated in
2237 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2238 configuration have in average 30,000 different possible virtual
2239 addresses for each memory section.
2243 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2244 hex "Physical memory mapping padding" if EXPERT
2245 depends on RANDOMIZE_MEMORY
2246 default "0xa" if MEMORY_HOTPLUG
2248 range 0x1 0x40 if MEMORY_HOTPLUG
2251 Define the padding in terabytes added to the existing physical
2252 memory size during kernel memory randomization. It is useful
2253 for memory hotplug support but reduces the entropy available for
2254 address randomization.
2256 If unsure, leave at the default value.
2258 config ADDRESS_MASKING
2259 bool "Linear Address Masking support"
2262 Linear Address Masking (LAM) modifies the checking that is applied
2263 to 64-bit linear addresses, allowing software to use of the
2264 untranslated address bits for metadata.
2266 The capability can be used for efficient address sanitizers (ASAN)
2267 implementation and for optimizations in JITs.
2275 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2276 depends on COMPAT_32
2278 Certain buggy versions of glibc will crash if they are
2279 presented with a 32-bit vDSO that is not mapped at the address
2280 indicated in its segment table.
2282 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2283 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2284 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2285 the only released version with the bug, but OpenSUSE 9
2286 contains a buggy "glibc 2.3.2".
2288 The symptom of the bug is that everything crashes on startup, saying:
2289 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2291 Saying Y here changes the default value of the vdso32 boot
2292 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2293 This works around the glibc bug but hurts performance.
2295 If unsure, say N: if you are compiling your own kernel, you
2296 are unlikely to be using a buggy version of glibc.
2299 prompt "vsyscall table for legacy applications"
2301 default LEGACY_VSYSCALL_XONLY
2303 Legacy user code that does not know how to find the vDSO expects
2304 to be able to issue three syscalls by calling fixed addresses in
2305 kernel space. Since this location is not randomized with ASLR,
2306 it can be used to assist security vulnerability exploitation.
2308 This setting can be changed at boot time via the kernel command
2309 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2310 is deprecated and can only be enabled using the kernel command
2313 On a system with recent enough glibc (2.14 or newer) and no
2314 static binaries, you can say None without a performance penalty
2315 to improve security.
2317 If unsure, select "Emulate execution only".
2319 config LEGACY_VSYSCALL_XONLY
2320 bool "Emulate execution only"
2322 The kernel traps and emulates calls into the fixed vsyscall
2323 address mapping and does not allow reads. This
2324 configuration is recommended when userspace might use the
2325 legacy vsyscall area but support for legacy binary
2326 instrumentation of legacy code is not needed. It mitigates
2327 certain uses of the vsyscall area as an ASLR-bypassing
2330 config LEGACY_VSYSCALL_NONE
2333 There will be no vsyscall mapping at all. This will
2334 eliminate any risk of ASLR bypass due to the vsyscall
2335 fixed address mapping. Attempts to use the vsyscalls
2336 will be reported to dmesg, so that either old or
2337 malicious userspace programs can be identified.
2342 bool "Built-in kernel command line"
2344 Allow for specifying boot arguments to the kernel at
2345 build time. On some systems (e.g. embedded ones), it is
2346 necessary or convenient to provide some or all of the
2347 kernel boot arguments with the kernel itself (that is,
2348 to not rely on the boot loader to provide them.)
2350 To compile command line arguments into the kernel,
2351 set this option to 'Y', then fill in the
2352 boot arguments in CONFIG_CMDLINE.
2354 Systems with fully functional boot loaders (i.e. non-embedded)
2355 should leave this option set to 'N'.
2358 string "Built-in kernel command string"
2359 depends on CMDLINE_BOOL
2362 Enter arguments here that should be compiled into the kernel
2363 image and used at boot time. If the boot loader provides a
2364 command line at boot time, it is appended to this string to
2365 form the full kernel command line, when the system boots.
2367 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2368 change this behavior.
2370 In most cases, the command line (whether built-in or provided
2371 by the boot loader) should specify the device for the root
2374 config CMDLINE_OVERRIDE
2375 bool "Built-in command line overrides boot loader arguments"
2376 depends on CMDLINE_BOOL && CMDLINE != ""
2378 Set this option to 'Y' to have the kernel ignore the boot loader
2379 command line, and use ONLY the built-in command line.
2381 This is used to work around broken boot loaders. This should
2382 be set to 'N' under normal conditions.
2384 config MODIFY_LDT_SYSCALL
2385 bool "Enable the LDT (local descriptor table)" if EXPERT
2388 Linux can allow user programs to install a per-process x86
2389 Local Descriptor Table (LDT) using the modify_ldt(2) system
2390 call. This is required to run 16-bit or segmented code such as
2391 DOSEMU or some Wine programs. It is also used by some very old
2392 threading libraries.
2394 Enabling this feature adds a small amount of overhead to
2395 context switches and increases the low-level kernel attack
2396 surface. Disabling it removes the modify_ldt(2) system call.
2398 Saying 'N' here may make sense for embedded or server kernels.
2400 config STRICT_SIGALTSTACK_SIZE
2401 bool "Enforce strict size checking for sigaltstack"
2402 depends on DYNAMIC_SIGFRAME
2404 For historical reasons MINSIGSTKSZ is a constant which became
2405 already too small with AVX512 support. Add a mechanism to
2406 enforce strict checking of the sigaltstack size against the
2407 real size of the FPU frame. This option enables the check
2408 by default. It can also be controlled via the kernel command
2409 line option 'strict_sas_size' independent of this config
2410 switch. Enabling it might break existing applications which
2411 allocate a too small sigaltstack but 'work' because they
2412 never get a signal delivered.
2414 Say 'N' unless you want to really enforce this check.
2416 source "kernel/livepatch/Kconfig"
2420 config CC_HAS_NAMED_AS
2421 def_bool CC_IS_GCC && GCC_VERSION >= 120100
2423 config USE_X86_SEG_SUPPORT
2425 depends on CC_HAS_NAMED_AS
2427 # -fsanitize=kernel-address (KASAN) is at the moment incompatible
2428 # with named address spaces - see GCC PR sanitizer/111736.
2431 # -fsanitize=thread (KCSAN) is also incompatible.
2435 def_bool $(cc-option,-mharden-sls=all)
2437 config CC_HAS_RETURN_THUNK
2438 def_bool $(cc-option,-mfunction-return=thunk-extern)
2440 config CC_HAS_ENTRY_PADDING
2441 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2443 config FUNCTION_PADDING_CFI
2445 default 59 if FUNCTION_ALIGNMENT_64B
2446 default 27 if FUNCTION_ALIGNMENT_32B
2447 default 11 if FUNCTION_ALIGNMENT_16B
2448 default 3 if FUNCTION_ALIGNMENT_8B
2451 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2452 # except Kconfig can't do arithmetic :/
2453 config FUNCTION_PADDING_BYTES
2455 default FUNCTION_PADDING_CFI if CFI_CLANG
2456 default FUNCTION_ALIGNMENT
2460 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2461 select FUNCTION_ALIGNMENT_16B
2465 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2468 config HAVE_CALL_THUNKS
2470 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2476 config PREFIX_SYMBOLS
2478 depends on CALL_PADDING && !CFI_CLANG
2480 menuconfig CPU_MITIGATIONS
2481 bool "Mitigations for CPU vulnerabilities"
2484 Say Y here to enable options which enable mitigations for hardware
2485 vulnerabilities (usually related to speculative execution).
2486 Mitigations can be disabled or restricted to SMT systems at runtime
2487 via the "mitigations" kernel parameter.
2489 If you say N, all mitigations will be disabled. This CANNOT be
2490 overridden at runtime.
2492 Say 'Y', unless you really know what you are doing.
2496 config MITIGATION_PAGE_TABLE_ISOLATION
2497 bool "Remove the kernel mapping in user mode"
2499 depends on (X86_64 || X86_PAE)
2501 This feature reduces the number of hardware side channels by
2502 ensuring that the majority of kernel addresses are not mapped
2505 See Documentation/arch/x86/pti.rst for more details.
2507 config MITIGATION_RETPOLINE
2508 bool "Avoid speculative indirect branches in kernel"
2509 select OBJTOOL if HAVE_OBJTOOL
2512 Compile kernel with the retpoline compiler options to guard against
2513 kernel-to-user data leaks by avoiding speculative indirect
2514 branches. Requires a compiler with -mindirect-branch=thunk-extern
2515 support for full protection. The kernel may run slower.
2517 config MITIGATION_RETHUNK
2518 bool "Enable return-thunks"
2519 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2520 select OBJTOOL if HAVE_OBJTOOL
2523 Compile the kernel with the return-thunks compiler option to guard
2524 against kernel-to-user data leaks by avoiding return speculation.
2525 Requires a compiler with -mfunction-return=thunk-extern
2526 support for full protection. The kernel may run slower.
2528 config MITIGATION_UNRET_ENTRY
2529 bool "Enable UNRET on kernel entry"
2530 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2533 Compile the kernel with support for the retbleed=unret mitigation.
2535 config MITIGATION_CALL_DEPTH_TRACKING
2536 bool "Mitigate RSB underflow with call depth tracking"
2537 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2538 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2542 Compile the kernel with call depth tracking to mitigate the Intel
2543 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2544 mitigation is off by default and needs to be enabled on the
2545 kernel command line via the retbleed=stuff option. For
2546 non-affected systems the overhead of this option is marginal as
2547 the call depth tracking is using run-time generated call thunks
2548 in a compiler generated padding area and call patching. This
2549 increases text size by ~5%. For non affected systems this space
2550 is unused. On affected SKL systems this results in a significant
2551 performance gain over the IBRS mitigation.
2553 config CALL_THUNKS_DEBUG
2554 bool "Enable call thunks and call depth tracking debugging"
2555 depends on MITIGATION_CALL_DEPTH_TRACKING
2556 select FUNCTION_ALIGNMENT_32B
2559 Enable call/ret counters for imbalance detection and build in
2560 a noisy dmesg about callthunks generation and call patching for
2561 trouble shooting. The debug prints need to be enabled on the
2562 kernel command line with 'debug-callthunks'.
2563 Only enable this when you are debugging call thunks as this
2564 creates a noticeable runtime overhead. If unsure say N.
2566 config MITIGATION_IBPB_ENTRY
2567 bool "Enable IBPB on kernel entry"
2568 depends on CPU_SUP_AMD && X86_64
2571 Compile the kernel with support for the retbleed=ibpb mitigation.
2573 config MITIGATION_IBRS_ENTRY
2574 bool "Enable IBRS on kernel entry"
2575 depends on CPU_SUP_INTEL && X86_64
2578 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2579 This mitigates both spectre_v2 and retbleed at great cost to
2582 config MITIGATION_SRSO
2583 bool "Mitigate speculative RAS overflow on AMD"
2584 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2587 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2589 config MITIGATION_SLS
2590 bool "Mitigate Straight-Line-Speculation"
2591 depends on CC_HAS_SLS && X86_64
2592 select OBJTOOL if HAVE_OBJTOOL
2595 Compile the kernel with straight-line-speculation options to guard
2596 against straight line speculation. The kernel image might be slightly
2599 config MITIGATION_GDS_FORCE
2600 bool "Force GDS Mitigation"
2601 depends on CPU_SUP_INTEL
2604 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2605 unprivileged speculative access to data which was previously stored in
2608 This option is equivalent to setting gather_data_sampling=force on the
2609 command line. The microcode mitigation is used if present, otherwise
2610 AVX is disabled as a mitigation. On affected systems that are missing
2611 the microcode any userspace code that unconditionally uses AVX will
2612 break with this option set.
2614 Setting this option on systems not vulnerable to GDS has no effect.
2618 config MITIGATION_RFDS
2619 bool "RFDS Mitigation"
2620 depends on CPU_SUP_INTEL
2623 Enable mitigation for Register File Data Sampling (RFDS) by default.
2624 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2625 allows unprivileged speculative access to stale data previously
2626 stored in floating point, vector and integer registers.
2627 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2629 config MITIGATION_SPECTRE_BHI
2630 bool "Mitigate Spectre-BHB (Branch History Injection)"
2631 depends on CPU_SUP_INTEL
2634 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2635 where the branch history buffer is poisoned to speculatively steer
2637 See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2641 config ARCH_HAS_ADD_PAGES
2643 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2645 menu "Power management and ACPI options"
2647 config ARCH_HIBERNATION_HEADER
2649 depends on HIBERNATION
2651 source "kernel/power/Kconfig"
2653 source "drivers/acpi/Kconfig"
2660 tristate "APM (Advanced Power Management) BIOS support"
2661 depends on X86_32 && PM_SLEEP
2663 APM is a BIOS specification for saving power using several different
2664 techniques. This is mostly useful for battery powered laptops with
2665 APM compliant BIOSes. If you say Y here, the system time will be
2666 reset after a RESUME operation, the /proc/apm device will provide
2667 battery status information, and user-space programs will receive
2668 notification of APM "events" (e.g. battery status change).
2670 If you select "Y" here, you can disable actual use of the APM
2671 BIOS by passing the "apm=off" option to the kernel at boot time.
2673 Note that the APM support is almost completely disabled for
2674 machines with more than one CPU.
2676 In order to use APM, you will need supporting software. For location
2677 and more information, read <file:Documentation/power/apm-acpi.rst>
2678 and the Battery Powered Linux mini-HOWTO, available from
2679 <http://www.tldp.org/docs.html#howto>.
2681 This driver does not spin down disk drives (see the hdparm(8)
2682 manpage ("man 8 hdparm") for that), and it doesn't turn off
2683 VESA-compliant "green" monitors.
2685 This driver does not support the TI 4000M TravelMate and the ACER
2686 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2687 desktop machines also don't have compliant BIOSes, and this driver
2688 may cause those machines to panic during the boot phase.
2690 Generally, if you don't have a battery in your machine, there isn't
2691 much point in using this driver and you should say N. If you get
2692 random kernel OOPSes or reboots that don't seem to be related to
2693 anything, try disabling/enabling this option (or disabling/enabling
2696 Some other things you should try when experiencing seemingly random,
2699 1) make sure that you have enough swap space and that it is
2701 2) pass the "idle=poll" option to the kernel
2702 3) switch on floating point emulation in the kernel and pass
2703 the "no387" option to the kernel
2704 4) pass the "floppy=nodma" option to the kernel
2705 5) pass the "mem=4M" option to the kernel (thereby disabling
2706 all but the first 4 MB of RAM)
2707 6) make sure that the CPU is not over clocked.
2708 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2709 8) disable the cache from your BIOS settings
2710 9) install a fan for the video card or exchange video RAM
2711 10) install a better fan for the CPU
2712 11) exchange RAM chips
2713 12) exchange the motherboard.
2715 To compile this driver as a module, choose M here: the
2716 module will be called apm.
2720 config APM_IGNORE_USER_SUSPEND
2721 bool "Ignore USER SUSPEND"
2723 This option will ignore USER SUSPEND requests. On machines with a
2724 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2725 series notebooks, it is necessary to say Y because of a BIOS bug.
2727 config APM_DO_ENABLE
2728 bool "Enable PM at boot time"
2730 Enable APM features at boot time. From page 36 of the APM BIOS
2731 specification: "When disabled, the APM BIOS does not automatically
2732 power manage devices, enter the Standby State, enter the Suspend
2733 State, or take power saving steps in response to CPU Idle calls."
2734 This driver will make CPU Idle calls when Linux is idle (unless this
2735 feature is turned off -- see "Do CPU IDLE calls", below). This
2736 should always save battery power, but more complicated APM features
2737 will be dependent on your BIOS implementation. You may need to turn
2738 this option off if your computer hangs at boot time when using APM
2739 support, or if it beeps continuously instead of suspending. Turn
2740 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2741 T400CDT. This is off by default since most machines do fine without
2746 bool "Make CPU Idle calls when idle"
2748 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2749 On some machines, this can activate improved power savings, such as
2750 a slowed CPU clock rate, when the machine is idle. These idle calls
2751 are made after the idle loop has run for some length of time (e.g.,
2752 333 mS). On some machines, this will cause a hang at boot time or
2753 whenever the CPU becomes idle. (On machines with more than one CPU,
2754 this option does nothing.)
2756 config APM_DISPLAY_BLANK
2757 bool "Enable console blanking using APM"
2759 Enable console blanking using the APM. Some laptops can use this to
2760 turn off the LCD backlight when the screen blanker of the Linux
2761 virtual console blanks the screen. Note that this is only used by
2762 the virtual console screen blanker, and won't turn off the backlight
2763 when using the X Window system. This also doesn't have anything to
2764 do with your VESA-compliant power-saving monitor. Further, this
2765 option doesn't work for all laptops -- it might not turn off your
2766 backlight at all, or it might print a lot of errors to the console,
2767 especially if you are using gpm.
2769 config APM_ALLOW_INTS
2770 bool "Allow interrupts during APM BIOS calls"
2772 Normally we disable external interrupts while we are making calls to
2773 the APM BIOS as a measure to lessen the effects of a badly behaving
2774 BIOS implementation. The BIOS should reenable interrupts if it
2775 needs to. Unfortunately, some BIOSes do not -- especially those in
2776 many of the newer IBM Thinkpads. If you experience hangs when you
2777 suspend, try setting this to Y. Otherwise, say N.
2781 source "drivers/cpufreq/Kconfig"
2783 source "drivers/cpuidle/Kconfig"
2785 source "drivers/idle/Kconfig"
2789 menu "Bus options (PCI etc.)"
2792 prompt "PCI access mode"
2793 depends on X86_32 && PCI
2796 On PCI systems, the BIOS can be used to detect the PCI devices and
2797 determine their configuration. However, some old PCI motherboards
2798 have BIOS bugs and may crash if this is done. Also, some embedded
2799 PCI-based systems don't have any BIOS at all. Linux can also try to
2800 detect the PCI hardware directly without using the BIOS.
2802 With this option, you can specify how Linux should detect the
2803 PCI devices. If you choose "BIOS", the BIOS will be used,
2804 if you choose "Direct", the BIOS won't be used, and if you
2805 choose "MMConfig", then PCI Express MMCONFIG will be used.
2806 If you choose "Any", the kernel will try MMCONFIG, then the
2807 direct access method and falls back to the BIOS if that doesn't
2808 work. If unsure, go with the default, which is "Any".
2813 config PCI_GOMMCONFIG
2830 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2832 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2835 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2838 bool "Support mmconfig PCI config space access" if X86_64
2840 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2841 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2845 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2849 depends on PCI && XEN
2851 config MMCONF_FAM10H
2853 depends on X86_64 && PCI_MMCONFIG && ACPI
2855 config PCI_CNB20LE_QUIRK
2856 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2859 Read the PCI windows out of the CNB20LE host bridge. This allows
2860 PCI hotplug to work on systems with the CNB20LE chipset which do
2863 There's no public spec for this chipset, and this functionality
2864 is known to be incomplete.
2866 You should say N unless you know you need this.
2869 bool "ISA bus support on modern systems" if EXPERT
2871 Expose ISA bus device drivers and options available for selection and
2872 configuration. Enable this option if your target machine has an ISA
2873 bus. ISA is an older system, displaced by PCI and newer bus
2874 architectures -- if your target machine is modern, it probably does
2875 not have an ISA bus.
2879 # x86_64 have no ISA slots, but can have ISA-style DMA.
2881 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2884 Enables ISA-style DMA support for devices requiring such controllers.
2892 Find out whether you have ISA slots on your motherboard. ISA is the
2893 name of a bus system, i.e. the way the CPU talks to the other stuff
2894 inside your box. Other bus systems are PCI, EISA, MicroChannel
2895 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2896 newer boards don't support it. If you have ISA, say Y, otherwise N.
2899 tristate "NatSemi SCx200 support"
2901 This provides basic support for National Semiconductor's
2902 (now AMD's) Geode processors. The driver probes for the
2903 PCI-IDs of several on-chip devices, so its a good dependency
2904 for other scx200_* drivers.
2906 If compiled as a module, the driver is named scx200.
2908 config SCx200HR_TIMER
2909 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2913 This driver provides a clocksource built upon the on-chip
2914 27MHz high-resolution timer. Its also a workaround for
2915 NSC Geode SC-1100's buggy TSC, which loses time when the
2916 processor goes idle (as is done by the scheduler). The
2917 other workaround is idle=poll boot option.
2920 bool "One Laptop Per Child support"
2928 Add support for detecting the unique features of the OLPC
2932 bool "OLPC XO-1 Power Management"
2933 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2935 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2938 bool "OLPC XO-1 Real Time Clock"
2939 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2941 Add support for the XO-1 real time clock, which can be used as a
2942 programmable wakeup source.
2945 bool "OLPC XO-1 SCI extras"
2946 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2950 Add support for SCI-based features of the OLPC XO-1 laptop:
2951 - EC-driven system wakeups
2955 - AC adapter status updates
2956 - Battery status updates
2958 config OLPC_XO15_SCI
2959 bool "OLPC XO-1.5 SCI extras"
2960 depends on OLPC && ACPI
2963 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2964 - EC-driven system wakeups
2965 - AC adapter status updates
2966 - Battery status updates
2969 bool "PCEngines ALIX System Support (LED setup)"
2972 This option enables system support for the PCEngines ALIX.
2973 At present this just sets up LEDs for GPIO control on
2974 ALIX2/3/6 boards. However, other system specific setup should
2977 Note: You must still enable the drivers for GPIO and LED support
2978 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2980 Note: You have to set alix.force=1 for boards with Award BIOS.
2983 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2986 This option enables system support for the Soekris Engineering net5501.
2989 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2993 This option enables system support for the Traverse Technologies GEOS.
2996 bool "Technologic Systems TS-5500 platform support"
2998 select CHECK_SIGNATURE
3002 This option enables system support for the Technologic Systems TS-5500.
3008 depends on CPU_SUP_AMD && PCI
3012 menu "Binary Emulations"
3014 config IA32_EMULATION
3015 bool "IA32 Emulation"
3017 select ARCH_WANT_OLD_COMPAT_IPC
3019 select COMPAT_OLD_SIGACTION
3021 Include code to run legacy 32-bit programs under a
3022 64-bit kernel. You should likely turn this on, unless you're
3023 100% sure that you don't have any 32-bit programs left.
3025 config IA32_EMULATION_DEFAULT_DISABLED
3026 bool "IA32 emulation disabled by default"
3028 depends on IA32_EMULATION
3030 Make IA32 emulation disabled by default. This prevents loading 32-bit
3031 processes and access to 32-bit syscalls. If unsure, leave it to its
3035 bool "x32 ABI for 64-bit mode"
3037 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3038 # compressed debug sections to x86_x32 properly:
3039 # https://github.com/ClangBuiltLinux/linux/issues/514
3040 # https://github.com/ClangBuiltLinux/linux/issues/1141
3041 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3043 Include code to run binaries for the x32 native 32-bit ABI
3044 for 64-bit processors. An x32 process gets access to the
3045 full 64-bit register file and wide data path while leaving
3046 pointers at 32 bits for smaller memory footprint.
3050 depends on IA32_EMULATION || X86_32
3052 select OLD_SIGSUSPEND3
3056 depends on IA32_EMULATION || X86_X32_ABI
3058 config COMPAT_FOR_U64_ALIGNMENT
3064 config HAVE_ATOMIC_IOMAP
3068 source "arch/x86/kvm/Kconfig"
3070 source "arch/x86/Kconfig.assembler"