1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_SUPPORTS_PER_VMA_LOCK
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
63 select ARCH_32BIT_OFF_T if X86_32
64 select ARCH_CLOCKSOURCE_INIT
65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
72 select ARCH_HAS_CACHE_LINE_SIZE
73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
74 select ARCH_HAS_CPU_FINALIZE_INIT
75 select ARCH_HAS_CPU_PASID if IOMMU_SVA
76 select ARCH_HAS_CURRENT_STACK_POINTER
77 select ARCH_HAS_DEBUG_VIRTUAL
78 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
79 select ARCH_HAS_DEVMEM_IS_ALLOWED
80 select ARCH_HAS_EARLY_DEBUG if KGDB
81 select ARCH_HAS_ELF_RANDOMIZE
82 select ARCH_HAS_FAST_MULTIPLIER
83 select ARCH_HAS_FORTIFY_SOURCE
84 select ARCH_HAS_GCOV_PROFILE_ALL
85 select ARCH_HAS_KCOV if X86_64
86 select ARCH_HAS_MEM_ENCRYPT
87 select ARCH_HAS_MEMBARRIER_SYNC_CORE
88 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
89 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
90 select ARCH_HAS_PMEM_API if X86_64
91 select ARCH_HAS_PTE_DEVMAP if X86_64
92 select ARCH_HAS_PTE_SPECIAL
93 select ARCH_HAS_HW_PTE_YOUNG
94 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
95 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
96 select ARCH_HAS_COPY_MC if X86_64
97 select ARCH_HAS_SET_MEMORY
98 select ARCH_HAS_SET_DIRECT_MAP
99 select ARCH_HAS_STRICT_KERNEL_RWX
100 select ARCH_HAS_STRICT_MODULE_RWX
101 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
102 select ARCH_HAS_SYSCALL_WRAPPER
103 select ARCH_HAS_UBSAN
104 select ARCH_HAS_DEBUG_WX
105 select ARCH_HAS_ZONE_DMA_SET if EXPERT
106 select ARCH_HAVE_NMI_SAFE_CMPXCHG
107 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
108 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
109 select ARCH_MIGHT_HAVE_PC_PARPORT
110 select ARCH_MIGHT_HAVE_PC_SERIO
111 select ARCH_STACKWALK
112 select ARCH_SUPPORTS_ACPI
113 select ARCH_SUPPORTS_ATOMIC_RMW
114 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
115 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
116 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
117 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
118 select ARCH_SUPPORTS_CFI_CLANG if X86_64
119 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
120 select ARCH_SUPPORTS_LTO_CLANG
121 select ARCH_SUPPORTS_LTO_CLANG_THIN
122 select ARCH_USE_BUILTIN_BSWAP
123 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
124 select ARCH_USE_MEMTEST
125 select ARCH_USE_QUEUED_RWLOCKS
126 select ARCH_USE_QUEUED_SPINLOCKS
127 select ARCH_USE_SYM_ANNOTATIONS
128 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
129 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
130 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
131 select ARCH_WANTS_NO_INSTR
132 select ARCH_WANT_GENERAL_HUGETLB
133 select ARCH_WANT_HUGE_PMD_SHARE
134 select ARCH_WANT_LD_ORPHAN_WARN
135 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
136 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
137 select ARCH_WANTS_THP_SWAP if X86_64
138 select ARCH_HAS_PARANOID_L1D_FLUSH
139 select BUILDTIME_TABLE_SORT
141 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
142 select CLOCKSOURCE_WATCHDOG
143 # Word-size accesses may read uninitialized data past the trailing \0
144 # in strings and cause false KMSAN reports.
145 select DCACHE_WORD_ACCESS if !KMSAN
146 select DYNAMIC_SIGFRAME
147 select EDAC_ATOMIC_SCRUB
149 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
150 select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST
151 select GENERIC_CLOCKEVENTS_MIN_ADJUST
152 select GENERIC_CMOS_UPDATE
153 select GENERIC_CPU_AUTOPROBE
154 select GENERIC_CPU_DEVICES
155 select GENERIC_CPU_VULNERABILITIES
156 select GENERIC_EARLY_IOREMAP
159 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
160 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
161 select GENERIC_IRQ_MIGRATION if SMP
162 select GENERIC_IRQ_PROBE
163 select GENERIC_IRQ_RESERVATION_MODE
164 select GENERIC_IRQ_SHOW
165 select GENERIC_PENDING_IRQ if SMP
166 select GENERIC_PTDUMP
167 select GENERIC_SMP_IDLE_THREAD
168 select GENERIC_TIME_VSYSCALL
169 select GENERIC_GETTIMEOFDAY
170 select GENERIC_VDSO_TIME_NS
171 select GUP_GET_PXX_LOW_HIGH if X86_PAE
172 select HARDIRQS_SW_RESEND
173 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
175 select HAVE_ACPI_APEI if ACPI
176 select HAVE_ACPI_APEI_NMI if ACPI
177 select HAVE_ALIGNED_STRUCT_PAGE
178 select HAVE_ARCH_AUDITSYSCALL
179 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
180 select HAVE_ARCH_HUGE_VMALLOC if X86_64
181 select HAVE_ARCH_JUMP_LABEL
182 select HAVE_ARCH_JUMP_LABEL_RELATIVE
183 select HAVE_ARCH_KASAN if X86_64
184 select HAVE_ARCH_KASAN_VMALLOC if X86_64
185 select HAVE_ARCH_KFENCE
186 select HAVE_ARCH_KMSAN if X86_64
187 select HAVE_ARCH_KGDB
188 select HAVE_ARCH_MMAP_RND_BITS if MMU
189 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
190 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
191 select HAVE_ARCH_PREL32_RELOCATIONS
192 select HAVE_ARCH_SECCOMP_FILTER
193 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
194 select HAVE_ARCH_STACKLEAK
195 select HAVE_ARCH_TRACEHOOK
196 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
197 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
198 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
199 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
200 select HAVE_ARCH_VMAP_STACK if X86_64
201 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
202 select HAVE_ARCH_WITHIN_STACK_FRAMES
203 select HAVE_ASM_MODVERSIONS
204 select HAVE_CMPXCHG_DOUBLE
205 select HAVE_CMPXCHG_LOCAL
206 select HAVE_CONTEXT_TRACKING_USER if X86_64
207 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
208 select HAVE_C_RECORDMCOUNT
209 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
210 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
211 select HAVE_BUILDTIME_MCOUNT_SORT
212 select HAVE_DEBUG_KMEMLEAK
213 select HAVE_DMA_CONTIGUOUS
214 select HAVE_DYNAMIC_FTRACE
215 select HAVE_DYNAMIC_FTRACE_WITH_REGS
216 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
217 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
218 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
219 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
221 select HAVE_EFFICIENT_UNALIGNED_ACCESS
223 select HAVE_EXIT_THREAD
225 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
226 select HAVE_FTRACE_MCOUNT_RECORD
227 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
228 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
229 select HAVE_FUNCTION_TRACER
230 select HAVE_GCC_PLUGINS
231 select HAVE_HW_BREAKPOINT
232 select HAVE_IOREMAP_PROT
233 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
234 select HAVE_IRQ_TIME_ACCOUNTING
235 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
236 select HAVE_KERNEL_BZIP2
237 select HAVE_KERNEL_GZIP
238 select HAVE_KERNEL_LZ4
239 select HAVE_KERNEL_LZMA
240 select HAVE_KERNEL_LZO
241 select HAVE_KERNEL_XZ
242 select HAVE_KERNEL_ZSTD
244 select HAVE_KPROBES_ON_FTRACE
245 select HAVE_FUNCTION_ERROR_INJECTION
246 select HAVE_KRETPROBES
249 select HAVE_LIVEPATCH if X86_64
250 select HAVE_MIXED_BREAKPOINTS_REGS
251 select HAVE_MOD_ARCH_SPECIFIC
254 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
256 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
257 select HAVE_OBJTOOL if X86_64
258 select HAVE_OPTPROBES
259 select HAVE_PAGE_SIZE_4KB
260 select HAVE_PCSPKR_PLATFORM
261 select HAVE_PERF_EVENTS
262 select HAVE_PERF_EVENTS_NMI
263 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
265 select HAVE_PERF_REGS
266 select HAVE_PERF_USER_STACK_DUMP
267 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
268 select MMU_GATHER_MERGE_VMAS
269 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
270 select HAVE_REGS_AND_STACK_ACCESS_API
271 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
272 select HAVE_FUNCTION_ARG_ACCESS_API
273 select HAVE_SETUP_PER_CPU_AREA
274 select HAVE_SOFTIRQ_ON_OWN_STACK
275 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
276 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
277 select HAVE_STATIC_CALL
278 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
279 select HAVE_PREEMPT_DYNAMIC_CALL
281 select HAVE_RUST if X86_64
282 select HAVE_SYSCALL_TRACEPOINTS
283 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
284 select HAVE_UNSTABLE_SCHED_CLOCK
285 select HAVE_USER_RETURN_NOTIFIER
286 select HAVE_GENERIC_VDSO
287 select HOTPLUG_PARALLEL if SMP && X86_64
288 select HOTPLUG_SMT if SMP
289 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
290 select IRQ_FORCED_THREADING
291 select LOCK_MM_AND_FIND_VMA
292 select NEED_PER_CPU_EMBED_FIRST_CHUNK
293 select NEED_PER_CPU_PAGE_FIRST_CHUNK
294 select NEED_SG_DMA_LENGTH
295 select PCI_DOMAINS if PCI
296 select PCI_LOCKLESS_CONFIG if PCI
299 select RTC_MC146818_LIB
301 select SYSCTL_EXCEPTION_TRACE
302 select THREAD_INFO_IN_TASK
303 select TRACE_IRQFLAGS_SUPPORT
304 select TRACE_IRQFLAGS_NMI_SUPPORT
305 select USER_STACKTRACE_SUPPORT
306 select HAVE_ARCH_KCSAN if X86_64
307 select PROC_PID_ARCH_STATUS if PROC_FS
308 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
309 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
310 select FUNCTION_ALIGNMENT_4B
311 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
312 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
314 config INSTRUCTION_DECODER
316 depends on KPROBES || PERF_EVENTS || UPROBES
320 default "elf32-i386" if X86_32
321 default "elf64-x86-64" if X86_64
323 config LOCKDEP_SUPPORT
326 config STACKTRACE_SUPPORT
332 config ARCH_MMAP_RND_BITS_MIN
336 config ARCH_MMAP_RND_BITS_MAX
340 config ARCH_MMAP_RND_COMPAT_BITS_MIN
343 config ARCH_MMAP_RND_COMPAT_BITS_MAX
349 config GENERIC_ISA_DMA
351 depends on ISA_DMA_API
355 default y if KMSAN || KASAN
360 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
362 config GENERIC_BUG_RELATIVE_POINTERS
365 config ARCH_MAY_HAVE_PC_FDC
367 depends on ISA_DMA_API
369 config GENERIC_CALIBRATE_DELAY
372 config ARCH_HAS_CPU_RELAX
375 config ARCH_HIBERNATION_POSSIBLE
378 config ARCH_SUSPEND_POSSIBLE
384 config KASAN_SHADOW_OFFSET
387 default 0xdffffc0000000000
389 config HAVE_INTEL_TXT
391 depends on INTEL_IOMMU && ACPI
395 depends on X86_64 && SMP
397 config ARCH_SUPPORTS_UPROBES
400 config FIX_EARLYCON_MEM
403 config DYNAMIC_PHYSICAL_MASK
406 config PGTABLE_LEVELS
408 default 5 if X86_5LEVEL
413 config CC_HAS_SANE_STACKPROTECTOR
415 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
416 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
418 We have to make sure stack protector is unconditionally disabled if
419 the compiler produces broken code or if it does not let us control
420 the segment on 32-bit kernels.
422 menu "Processor type and features"
425 bool "Symmetric multi-processing support"
427 This enables support for systems with more than one CPU. If you have
428 a system with only one CPU, say N. If you have a system with more
431 If you say N here, the kernel will run on uni- and multiprocessor
432 machines, but will use only one CPU of a multiprocessor machine. If
433 you say Y here, the kernel will run on many, but not all,
434 uniprocessor machines. On a uniprocessor machine, the kernel
435 will run faster if you say N here.
437 Note that if you say Y here and choose architecture "586" or
438 "Pentium" under "Processor family", the kernel will not work on 486
439 architectures. Similarly, multiprocessor kernels for the "PPro"
440 architecture may not work on all Pentium based boards.
442 People using multiprocessor machines who say Y here should also say
443 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
444 Management" code will be disabled if you say Y here.
446 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
447 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
448 <http://www.tldp.org/docs.html#howto>.
450 If you don't know what to do here, say N.
453 bool "Support x2apic"
454 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
456 This enables x2apic support on CPUs that have this feature.
458 This allows 32-bit apic IDs (so it can support very large systems),
459 and accesses the local apic via MSRs not via mmio.
461 Some Intel systems circa 2022 and later are locked into x2APIC mode
462 and can not fall back to the legacy APIC modes if SGX or TDX are
463 enabled in the BIOS. They will boot with very reduced functionality
464 without enabling this option.
466 If you don't know what to do here, say N.
469 bool "Enable MPS table" if ACPI
471 depends on X86_LOCAL_APIC
473 For old smp systems that do not have proper acpi support. Newer systems
474 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
478 depends on X86_GOLDFISH
480 config X86_CPU_RESCTRL
481 bool "x86 CPU resource control support"
482 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
484 select PROC_CPU_RESCTRL if PROC_FS
486 Enable x86 CPU resource control support.
488 Provide support for the allocation and monitoring of system resources
491 Intel calls this Intel Resource Director Technology
492 (Intel(R) RDT). More information about RDT can be found in the
493 Intel x86 Architecture Software Developer Manual.
495 AMD calls this AMD Platform Quality of Service (AMD QoS).
496 More information about AMD QoS can be found in the AMD64 Technology
497 Platform Quality of Service Extensions manual.
502 bool "Flexible Return and Event Delivery"
505 When enabled, try to use Flexible Return and Event Delivery
506 instead of the legacy SYSCALL/SYSENTER/IDT architecture for
507 ring transitions and exception/interrupt handling if the
512 bool "Support for big SMP systems with more than 8 CPUs"
515 This option is needed for the systems that have more than 8 CPUs.
517 config X86_EXTENDED_PLATFORM
518 bool "Support for extended (non-PC) x86 platforms"
521 If you disable this option then the kernel will only support
522 standard PC platforms. (which covers the vast majority of
525 If you enable this option then you'll be able to select support
526 for the following (non-PC) 32 bit x86 platforms:
527 Goldfish (Android emulator)
530 SGI 320/540 (Visual Workstation)
531 STA2X11-based (e.g. Northville)
532 Moorestown MID devices
534 If you have one of these systems, or if you want to build a
535 generic distribution kernel, say Y here - otherwise say N.
539 config X86_EXTENDED_PLATFORM
540 bool "Support for extended (non-PC) x86 platforms"
543 If you disable this option then the kernel will only support
544 standard PC platforms. (which covers the vast majority of
547 If you enable this option then you'll be able to select support
548 for the following (non-PC) 64 bit x86 platforms:
553 If you have one of these systems, or if you want to build a
554 generic distribution kernel, say Y here - otherwise say N.
556 # This is an alphabetically sorted list of 64 bit extended platforms
557 # Please maintain the alphabetic order if and when there are additions
559 bool "Numascale NumaChip"
561 depends on X86_EXTENDED_PLATFORM
564 depends on X86_X2APIC
565 depends on PCI_MMCONFIG
567 Adds support for Numascale NumaChip large-SMP systems. Needed to
568 enable more than ~168 cores.
569 If you don't have one of these, you should say N here.
573 select HYPERVISOR_GUEST
575 depends on X86_64 && PCI
576 depends on X86_EXTENDED_PLATFORM
579 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
580 supposed to run on these EM64T-based machines. Only choose this option
581 if you have one of these machines.
584 bool "SGI Ultraviolet"
586 depends on X86_EXTENDED_PLATFORM
589 depends on KEXEC_CORE
590 depends on X86_X2APIC
593 This option is needed in order to support SGI Ultraviolet systems.
594 If you don't have one of these, you should say N here.
596 # Following is an alphabetically sorted list of 32 bit extended platforms
597 # Please maintain the alphabetic order if and when there are additions
600 bool "Goldfish (Virtual Platform)"
601 depends on X86_EXTENDED_PLATFORM
603 Enable support for the Goldfish virtual platform used primarily
604 for Android development. Unless you are building for the Android
605 Goldfish emulator say N here.
608 bool "CE4100 TV platform"
610 depends on PCI_GODIRECT
611 depends on X86_IO_APIC
613 depends on X86_EXTENDED_PLATFORM
614 select X86_REBOOTFIXUPS
616 select OF_EARLY_FLATTREE
618 Select for the Intel CE media processor (CE4100) SOC.
619 This option compiles in support for the CE4100 SOC for settop
620 boxes and media devices.
623 bool "Intel MID platform support"
624 depends on X86_EXTENDED_PLATFORM
625 depends on X86_PLATFORM_DEVICES
627 depends on X86_64 || (PCI_GOANY && X86_32)
628 depends on X86_IO_APIC
633 Select to build a kernel capable of supporting Intel MID (Mobile
634 Internet Device) platform systems which do not have the PCI legacy
635 interfaces. If you are building for a PC class system say N here.
637 Intel MID platforms are based on an Intel processor and chipset which
638 consume less power than most of the x86 derivatives.
640 config X86_INTEL_QUARK
641 bool "Intel Quark platform support"
643 depends on X86_EXTENDED_PLATFORM
644 depends on X86_PLATFORM_DEVICES
648 depends on X86_IO_APIC
653 Select to include support for Quark X1000 SoC.
654 Say Y here if you have a Quark based system such as the Arduino
655 compatible Intel Galileo.
657 config X86_INTEL_LPSS
658 bool "Intel Low Power Subsystem Support"
659 depends on X86 && ACPI && PCI
664 Select to build support for Intel Low Power Subsystem such as
665 found on Intel Lynxpoint PCH. Selecting this option enables
666 things like clock tree (common clock framework) and pincontrol
667 which are needed by the LPSS peripheral drivers.
669 config X86_AMD_PLATFORM_DEVICE
670 bool "AMD ACPI2Platform devices support"
675 Select to interpret AMD specific ACPI device to platform device
676 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
677 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
678 implemented under PINCTRL subsystem.
681 tristate "Intel SoC IOSF Sideband support for SoC platforms"
684 This option enables sideband register access support for Intel SoC
685 platforms. On these platforms the IOSF sideband is used in lieu of
686 MSR's for some register accesses, mostly but not limited to thermal
687 and power. Drivers may query the availability of this device to
688 determine if they need the sideband in order to work on these
689 platforms. The sideband is available on the following SoC products.
690 This list is not meant to be exclusive.
695 You should say Y if you are running a kernel on one of these SoC's.
697 config IOSF_MBI_DEBUG
698 bool "Enable IOSF sideband access through debugfs"
699 depends on IOSF_MBI && DEBUG_FS
701 Select this option to expose the IOSF sideband access registers (MCR,
702 MDR, MCRX) through debugfs to write and read register information from
703 different units on the SoC. This is most useful for obtaining device
704 state information for debug and analysis. As this is a general access
705 mechanism, users of this option would have specific knowledge of the
706 device they want to access.
708 If you don't require the option or are in doubt, say N.
711 bool "RDC R-321x SoC"
713 depends on X86_EXTENDED_PLATFORM
715 select X86_REBOOTFIXUPS
717 This option is needed for RDC R-321x system-on-chip, also known
719 If you don't have one of these chips, you should say N here.
721 config X86_32_NON_STANDARD
722 bool "Support non-standard 32-bit SMP architectures"
723 depends on X86_32 && SMP
724 depends on X86_EXTENDED_PLATFORM
726 This option compiles in the bigsmp and STA2X11 default
727 subarchitectures. It is intended for a generic binary
728 kernel. If you select them all, kernel will probe it one by
729 one and will fallback to default.
731 # Alphabetically sorted list of Non standard 32 bit platforms
733 config X86_SUPPORTS_MEMORY_FAILURE
735 # MCE code calls memory_failure():
737 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
738 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
739 depends on X86_64 || !SPARSEMEM
740 select ARCH_SUPPORTS_MEMORY_FAILURE
743 bool "STA2X11 Companion Chip Support"
744 depends on X86_32_NON_STANDARD && PCI
749 This adds support for boards based on the STA2X11 IO-Hub,
750 a.k.a. "ConneXt". The chip is used in place of the standard
751 PC chipset, so all "standard" peripherals are missing. If this
752 option is selected the kernel will still be able to boot on
753 standard PC machines.
756 tristate "Eurobraille/Iris poweroff module"
759 The Iris machines from EuroBraille do not have APM or ACPI support
760 to shut themselves down properly. A special I/O sequence is
761 needed to do so, which is what this module does at
764 This is only for Iris machines from EuroBraille.
768 config SCHED_OMIT_FRAME_POINTER
770 prompt "Single-depth WCHAN output"
773 Calculate simpler /proc/<PID>/wchan values. If this option
774 is disabled then wchan values will recurse back to the
775 caller function. This provides more accurate wchan values,
776 at the expense of slightly more scheduling overhead.
778 If in doubt, say "Y".
780 menuconfig HYPERVISOR_GUEST
781 bool "Linux guest support"
783 Say Y here to enable options for running Linux under various hyper-
784 visors. This option enables basic hypervisor detection and platform
787 If you say N, all options in this submenu will be skipped and
788 disabled, and Linux guest support won't be built in.
793 bool "Enable paravirtualization code"
794 depends on HAVE_STATIC_CALL
796 This changes the kernel so it can modify itself when it is run
797 under a hypervisor, potentially improving performance significantly
798 over full virtualization. However, when run without a hypervisor
799 the kernel is theoretically slower and slightly larger.
804 config PARAVIRT_DEBUG
805 bool "paravirt-ops debugging"
806 depends on PARAVIRT && DEBUG_KERNEL
808 Enable to debug paravirt_ops internals. Specifically, BUG if
809 a paravirt_op is missing when it is called.
811 config PARAVIRT_SPINLOCKS
812 bool "Paravirtualization layer for spinlocks"
813 depends on PARAVIRT && SMP
815 Paravirtualized spinlocks allow a pvops backend to replace the
816 spinlock implementation with something virtualization-friendly
817 (for example, block the virtual CPU rather than spinning).
819 It has a minimal impact on native kernels and gives a nice performance
820 benefit on paravirtualized KVM / Xen kernels.
822 If you are unsure how to answer this question, answer Y.
824 config X86_HV_CALLBACK_VECTOR
827 source "arch/x86/xen/Kconfig"
830 bool "KVM Guest support (including kvmclock)"
832 select PARAVIRT_CLOCK
833 select ARCH_CPUIDLE_HALTPOLL
834 select X86_HV_CALLBACK_VECTOR
837 This option enables various optimizations for running under the KVM
838 hypervisor. It includes a paravirtualized clock, so that instead
839 of relying on a PIT (or probably other) emulation by the
840 underlying device model, the host provides the guest with
841 timing infrastructure such as time of day, and system time
843 config ARCH_CPUIDLE_HALTPOLL
845 prompt "Disable host haltpoll when loading haltpoll driver"
847 If virtualized under KVM, disable host haltpoll.
850 bool "Support for running PVH guests"
852 This option enables the PVH entry point for guest virtual machines
853 as specified in the x86/HVM direct boot ABI.
855 config PARAVIRT_TIME_ACCOUNTING
856 bool "Paravirtual steal time accounting"
859 Select this option to enable fine granularity task steal time
860 accounting. Time spent executing other tasks in parallel with
861 the current vCPU is discounted from the vCPU power. To account for
862 that, there can be a small performance impact.
864 If in doubt, say N here.
866 config PARAVIRT_CLOCK
869 config JAILHOUSE_GUEST
870 bool "Jailhouse non-root cell support"
871 depends on X86_64 && PCI
874 This option allows to run Linux as guest in a Jailhouse non-root
875 cell. You can leave this option disabled if you only want to start
876 Jailhouse and run Linux afterwards in the root cell.
879 bool "ACRN Guest support"
881 select X86_HV_CALLBACK_VECTOR
883 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
884 a flexible, lightweight reference open-source hypervisor, built with
885 real-time and safety-criticality in mind. It is built for embedded
886 IOT with small footprint and real-time features. More details can be
887 found in https://projectacrn.org/.
889 config INTEL_TDX_GUEST
890 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
891 depends on X86_64 && CPU_SUP_INTEL
892 depends on X86_X2APIC
894 select ARCH_HAS_CC_PLATFORM
895 select X86_MEM_ENCRYPT
897 select UNACCEPTED_MEMORY
899 Support running as a guest under Intel TDX. Without this support,
900 the guest kernel can not boot or run under TDX.
901 TDX includes memory encryption and integrity capabilities
902 which protect the confidentiality and integrity of guest
903 memory contents and CPU state. TDX guests are protected from
904 some attacks from the VMM.
906 endif # HYPERVISOR_GUEST
908 source "arch/x86/Kconfig.cpu"
912 prompt "HPET Timer Support" if X86_32
914 Use the IA-PC HPET (High Precision Event Timer) to manage
915 time in preference to the PIT and RTC, if a HPET is
917 HPET is the next generation timer replacing legacy 8254s.
918 The HPET provides a stable time base on SMP
919 systems, unlike the TSC, but it is more expensive to access,
920 as it is off-chip. The interface used is documented
921 in the HPET spec, revision 1.
923 You can safely choose Y here. However, HPET will only be
924 activated if the platform and the BIOS support this feature.
925 Otherwise the 8254 will be used for timing services.
927 Choose N to continue using the legacy 8254 timer.
929 config HPET_EMULATE_RTC
931 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
933 # Mark as expert because too many people got it wrong.
934 # The code disables itself when not needed.
937 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
938 bool "Enable DMI scanning" if EXPERT
940 Enabled scanning of DMI to identify machine quirks. Say Y
941 here unless you have verified that your setup is not
942 affected by entries in the DMI blacklist. Required by PNP
946 bool "Old AMD GART IOMMU support"
950 depends on X86_64 && PCI && AMD_NB
952 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
953 GART based hardware IOMMUs.
955 The GART supports full DMA access for devices with 32-bit access
956 limitations, on systems with more than 3 GB. This is usually needed
957 for USB, sound, many IDE/SATA chipsets and some other devices.
959 Newer systems typically have a modern AMD IOMMU, supported via
960 the CONFIG_AMD_IOMMU=y config option.
962 In normal configurations this driver is only active when needed:
963 there's more than 3 GB of memory and the system contains a
964 32-bit limited device.
968 config BOOT_VESA_SUPPORT
971 If true, at least one selected framebuffer driver can take advantage
972 of VESA video modes set at an early boot stage via the vga= parameter.
975 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
976 depends on X86_64 && SMP && DEBUG_KERNEL
977 select CPUMASK_OFFSTACK
979 Enable maximum number of CPUS and NUMA Nodes for this architecture.
983 # The maximum number of CPUs supported:
985 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
986 # and which can be configured interactively in the
987 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
989 # The ranges are different on 32-bit and 64-bit kernels, depending on
990 # hardware capabilities and scalability features of the kernel.
992 # ( If MAXSMP is enabled we just use the highest possible value and disable
993 # interactive configuration. )
996 config NR_CPUS_RANGE_BEGIN
998 default NR_CPUS_RANGE_END if MAXSMP
1002 config NR_CPUS_RANGE_END
1005 default 64 if SMP && X86_BIGSMP
1006 default 8 if SMP && !X86_BIGSMP
1009 config NR_CPUS_RANGE_END
1012 default 8192 if SMP && CPUMASK_OFFSTACK
1013 default 512 if SMP && !CPUMASK_OFFSTACK
1016 config NR_CPUS_DEFAULT
1019 default 32 if X86_BIGSMP
1023 config NR_CPUS_DEFAULT
1026 default 8192 if MAXSMP
1031 int "Maximum number of CPUs" if SMP && !MAXSMP
1032 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1033 default NR_CPUS_DEFAULT
1035 This allows you to specify the maximum number of CPUs which this
1036 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1037 supported value is 8192, otherwise the maximum value is 512. The
1038 minimum value which makes sense is 2.
1040 This is purely to save memory: each supported CPU adds about 8KB
1041 to the kernel image.
1043 config SCHED_CLUSTER
1044 bool "Cluster scheduler support"
1048 Cluster scheduler support improves the CPU scheduler's decision
1049 making when dealing with machines that have clusters of CPUs.
1050 Cluster usually means a couple of CPUs which are placed closely
1051 by sharing mid-level caches, last-level cache tags or internal
1059 prompt "Multi-core scheduler support"
1062 Multi-core scheduler support improves the CPU scheduler's decision
1063 making when dealing with multi-core CPU chips at a cost of slightly
1064 increased overhead in some places. If unsure say N here.
1066 config SCHED_MC_PRIO
1067 bool "CPU core priorities scheduler support"
1069 select X86_INTEL_PSTATE if CPU_SUP_INTEL
1070 select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
1074 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1075 core ordering determined at manufacturing time, which allows
1076 certain cores to reach higher turbo frequencies (when running
1077 single threaded workloads) than others.
1079 Enabling this kernel feature teaches the scheduler about
1080 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1081 scheduler's CPU selection logic accordingly, so that higher
1082 overall system performance can be achieved.
1084 This feature will have no effect on CPUs without this feature.
1086 If unsure say Y here.
1090 depends on !SMP && X86_LOCAL_APIC
1093 bool "Local APIC support on uniprocessors" if !PCI_MSI
1095 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1097 A local APIC (Advanced Programmable Interrupt Controller) is an
1098 integrated interrupt controller in the CPU. If you have a single-CPU
1099 system which has a processor with a local APIC, you can say Y here to
1100 enable and use it. If you say Y here even though your machine doesn't
1101 have a local APIC, then the kernel will still run with no slowdown at
1102 all. The local APIC supports CPU-generated self-interrupts (timer,
1103 performance counters), and the NMI watchdog which detects hard
1106 config X86_UP_IOAPIC
1107 bool "IO-APIC support on uniprocessors"
1108 depends on X86_UP_APIC
1110 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1111 SMP-capable replacement for PC-style interrupt controllers. Most
1112 SMP systems and many recent uniprocessor systems have one.
1114 If you have a single-CPU system with an IO-APIC, you can say Y here
1115 to use it. If you say Y here even though your machine doesn't have
1116 an IO-APIC, then the kernel will still run with no slowdown at all.
1118 config X86_LOCAL_APIC
1120 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1121 select IRQ_DOMAIN_HIERARCHY
1125 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1127 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1128 bool "Reroute for broken boot IRQs"
1129 depends on X86_IO_APIC
1131 This option enables a workaround that fixes a source of
1132 spurious interrupts. This is recommended when threaded
1133 interrupt handling is used on systems where the generation of
1134 superfluous "boot interrupts" cannot be disabled.
1136 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1137 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1138 kernel does during interrupt handling). On chipsets where this
1139 boot IRQ generation cannot be disabled, this workaround keeps
1140 the original IRQ line masked so that only the equivalent "boot
1141 IRQ" is delivered to the CPUs. The workaround also tells the
1142 kernel to set up the IRQ handler on the boot IRQ line. In this
1143 way only one interrupt is delivered to the kernel. Otherwise
1144 the spurious second interrupt may cause the kernel to bring
1145 down (vital) interrupt lines.
1147 Only affects "broken" chipsets. Interrupt sharing may be
1148 increased on these systems.
1151 bool "Machine Check / overheating reporting"
1152 select GENERIC_ALLOCATOR
1155 Machine Check support allows the processor to notify the
1156 kernel if it detects a problem (e.g. overheating, data corruption).
1157 The action the kernel takes depends on the severity of the problem,
1158 ranging from warning messages to halting the machine.
1160 config X86_MCELOG_LEGACY
1161 bool "Support for deprecated /dev/mcelog character device"
1164 Enable support for /dev/mcelog which is needed by the old mcelog
1165 userspace logging daemon. Consider switching to the new generation
1168 config X86_MCE_INTEL
1170 prompt "Intel MCE features"
1171 depends on X86_MCE && X86_LOCAL_APIC
1173 Additional support for intel specific MCE features such as
1174 the thermal monitor.
1178 prompt "AMD MCE features"
1179 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1181 Additional support for AMD specific MCE features such as
1182 the DRAM Error Threshold.
1184 config X86_ANCIENT_MCE
1185 bool "Support for old Pentium 5 / WinChip machine checks"
1186 depends on X86_32 && X86_MCE
1188 Include support for machine check handling on old Pentium 5 or WinChip
1189 systems. These typically need to be enabled explicitly on the command
1192 config X86_MCE_THRESHOLD
1193 depends on X86_MCE_AMD || X86_MCE_INTEL
1196 config X86_MCE_INJECT
1197 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1198 tristate "Machine check injector support"
1200 Provide support for injecting machine checks for testing purposes.
1201 If you don't know what a machine check is and you don't do kernel
1202 QA it is safe to say n.
1204 source "arch/x86/events/Kconfig"
1206 config X86_LEGACY_VM86
1207 bool "Legacy VM86 support"
1210 This option allows user programs to put the CPU into V8086
1211 mode, which is an 80286-era approximation of 16-bit real mode.
1213 Some very old versions of X and/or vbetool require this option
1214 for user mode setting. Similarly, DOSEMU will use it if
1215 available to accelerate real mode DOS programs. However, any
1216 recent version of DOSEMU, X, or vbetool should be fully
1217 functional even without kernel VM86 support, as they will all
1218 fall back to software emulation. Nevertheless, if you are using
1219 a 16-bit DOS program where 16-bit performance matters, vm86
1220 mode might be faster than emulation and you might want to
1223 Note that any app that works on a 64-bit kernel is unlikely to
1224 need this option, as 64-bit kernels don't, and can't, support
1225 V8086 mode. This option is also unrelated to 16-bit protected
1226 mode and is not needed to run most 16-bit programs under Wine.
1228 Enabling this option increases the complexity of the kernel
1229 and slows down exception handling a tiny bit.
1231 If unsure, say N here.
1235 default X86_LEGACY_VM86
1238 bool "Enable support for 16-bit segments" if EXPERT
1240 depends on MODIFY_LDT_SYSCALL
1242 This option is required by programs like Wine to run 16-bit
1243 protected mode legacy code on x86 processors. Disabling
1244 this option saves about 300 bytes on i386, or around 6K text
1245 plus 16K runtime memory on x86-64,
1249 depends on X86_16BIT && X86_32
1253 depends on X86_16BIT && X86_64
1255 config X86_VSYSCALL_EMULATION
1256 bool "Enable vsyscall emulation" if EXPERT
1260 This enables emulation of the legacy vsyscall page. Disabling
1261 it is roughly equivalent to booting with vsyscall=none, except
1262 that it will also disable the helpful warning if a program
1263 tries to use a vsyscall. With this option set to N, offending
1264 programs will just segfault, citing addresses of the form
1267 This option is required by many programs built before 2013, and
1268 care should be used even with newer programs if set to N.
1270 Disabling this option saves about 7K of kernel size and
1271 possibly 4K of additional runtime pagetable memory.
1273 config X86_IOPL_IOPERM
1274 bool "IOPERM and IOPL Emulation"
1277 This enables the ioperm() and iopl() syscalls which are necessary
1278 for legacy applications.
1280 Legacy IOPL support is an overbroad mechanism which allows user
1281 space aside of accessing all 65536 I/O ports also to disable
1282 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1283 capabilities and permission from potentially active security
1286 The emulation restricts the functionality of the syscall to
1287 only allowing the full range I/O port access, but prevents the
1288 ability to disable interrupts from user space which would be
1289 granted if the hardware IOPL mechanism would be used.
1292 tristate "Toshiba Laptop support"
1295 This adds a driver to safely access the System Management Mode of
1296 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1297 not work on models with a Phoenix BIOS. The System Management Mode
1298 is used to set the BIOS and power saving options on Toshiba portables.
1300 For information on utilities to make use of this driver see the
1301 Toshiba Linux utilities web site at:
1302 <http://www.buzzard.org.uk/toshiba/>.
1304 Say Y if you intend to run this kernel on a Toshiba portable.
1307 config X86_REBOOTFIXUPS
1308 bool "Enable X86 board specific fixups for reboot"
1311 This enables chipset and/or board specific fixups to be done
1312 in order to get reboot to work correctly. This is only needed on
1313 some combinations of hardware and BIOS. The symptom, for which
1314 this config is intended, is when reboot ends with a stalled/hung
1317 Currently, the only fixup is for the Geode machines using
1318 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1320 Say Y if you want to enable the fixup. Currently, it's safe to
1321 enable this option even if you don't need it.
1326 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1328 config MICROCODE_INITRD32
1330 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1332 config MICROCODE_LATE_LOADING
1333 bool "Late microcode loading (DANGEROUS)"
1335 depends on MICROCODE && SMP
1337 Loading microcode late, when the system is up and executing instructions
1338 is a tricky business and should be avoided if possible. Just the sequence
1339 of synchronizing all cores and SMT threads is one fragile dance which does
1340 not guarantee that cores might not softlock after the loading. Therefore,
1341 use this at your own risk. Late loading taints the kernel unless the
1342 microcode header indicates that it is safe for late loading via the
1343 minimal revision check. This minimal revision check can be enforced on
1344 the kernel command line with "microcode.minrev=Y".
1346 config MICROCODE_LATE_FORCE_MINREV
1347 bool "Enforce late microcode loading minimal revision check"
1349 depends on MICROCODE_LATE_LOADING
1351 To prevent that users load microcode late which modifies already
1352 in use features, newer microcode patches have a minimum revision field
1353 in the microcode header, which tells the kernel which minimum
1354 revision must be active in the CPU to safely load that new microcode
1355 late into the running system. If disabled the check will not
1356 be enforced but the kernel will be tainted when the minimal
1357 revision check fails.
1359 This minimal revision check can also be controlled via the
1360 "microcode.minrev" parameter on the kernel command line.
1365 tristate "/dev/cpu/*/msr - Model-specific register support"
1367 This device gives privileged processes access to the x86
1368 Model-Specific Registers (MSRs). It is a character device with
1369 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1370 MSR accesses are directed to a specific CPU on multi-processor
1374 tristate "/dev/cpu/*/cpuid - CPU information support"
1376 This device gives processes access to the x86 CPUID instruction to
1377 be executed on a specific processor. It is a character device
1378 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1382 prompt "High Memory Support"
1389 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1390 However, the address space of 32-bit x86 processors is only 4
1391 Gigabytes large. That means that, if you have a large amount of
1392 physical memory, not all of it can be "permanently mapped" by the
1393 kernel. The physical memory that's not permanently mapped is called
1396 If you are compiling a kernel which will never run on a machine with
1397 more than 1 Gigabyte total physical RAM, answer "off" here (default
1398 choice and suitable for most users). This will result in a "3GB/1GB"
1399 split: 3GB are mapped so that each process sees a 3GB virtual memory
1400 space and the remaining part of the 4GB virtual memory space is used
1401 by the kernel to permanently map as much physical memory as
1404 If the machine has between 1 and 4 Gigabytes physical RAM, then
1407 If more than 4 Gigabytes is used then answer "64GB" here. This
1408 selection turns Intel PAE (Physical Address Extension) mode on.
1409 PAE implements 3-level paging on IA32 processors. PAE is fully
1410 supported by Linux, PAE mode is implemented on all recent Intel
1411 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1412 then the kernel will not boot on CPUs that don't support PAE!
1414 The actual amount of total physical memory will either be
1415 auto detected or can be forced by using a kernel command line option
1416 such as "mem=256M". (Try "man bootparam" or see the documentation of
1417 your boot loader (lilo or loadlin) about how to pass options to the
1418 kernel at boot time.)
1420 If unsure, say "off".
1425 Select this if you have a 32-bit processor and between 1 and 4
1426 gigabytes of physical RAM.
1430 depends on X86_HAVE_PAE
1433 Select this if you have a 32-bit processor and more than 4
1434 gigabytes of physical RAM.
1439 prompt "Memory split" if EXPERT
1443 Select the desired split between kernel and user memory.
1445 If the address range available to the kernel is less than the
1446 physical memory installed, the remaining memory will be available
1447 as "high memory". Accessing high memory is a little more costly
1448 than low memory, as it needs to be mapped into the kernel first.
1449 Note that increasing the kernel address space limits the range
1450 available to user programs, making the address space there
1451 tighter. Selecting anything other than the default 3G/1G split
1452 will also likely make your kernel incompatible with binary-only
1455 If you are not absolutely sure what you are doing, leave this
1459 bool "3G/1G user/kernel split"
1460 config VMSPLIT_3G_OPT
1462 bool "3G/1G user/kernel split (for full 1G low memory)"
1464 bool "2G/2G user/kernel split"
1465 config VMSPLIT_2G_OPT
1467 bool "2G/2G user/kernel split (for full 2G low memory)"
1469 bool "1G/3G user/kernel split"
1474 default 0xB0000000 if VMSPLIT_3G_OPT
1475 default 0x80000000 if VMSPLIT_2G
1476 default 0x78000000 if VMSPLIT_2G_OPT
1477 default 0x40000000 if VMSPLIT_1G
1483 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1486 bool "PAE (Physical Address Extension) Support"
1487 depends on X86_32 && X86_HAVE_PAE
1488 select PHYS_ADDR_T_64BIT
1491 PAE is required for NX support, and furthermore enables
1492 larger swapspace support for non-overcommit purposes. It
1493 has the cost of more pagetable lookup overhead, and also
1494 consumes more pagetable space per process.
1497 bool "Enable 5-level page tables support"
1499 select DYNAMIC_MEMORY_LAYOUT
1500 select SPARSEMEM_VMEMMAP
1503 5-level paging enables access to larger address space:
1504 up to 128 PiB of virtual address space and 4 PiB of
1505 physical address space.
1507 It will be supported by future Intel CPUs.
1509 A kernel with the option enabled can be booted on machines that
1510 support 4- or 5-level paging.
1512 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1517 config X86_DIRECT_GBPAGES
1521 Certain kernel features effectively disable kernel
1522 linear 1 GB mappings (even if the CPU otherwise
1523 supports them), so don't confuse the user by printing
1524 that we have them enabled.
1526 config X86_CPA_STATISTICS
1527 bool "Enable statistic for Change Page Attribute"
1530 Expose statistics about the Change Page Attribute mechanism, which
1531 helps to determine the effectiveness of preserving large and huge
1532 page mappings when mapping protections are changed.
1534 config X86_MEM_ENCRYPT
1535 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1536 select DYNAMIC_PHYSICAL_MASK
1539 config AMD_MEM_ENCRYPT
1540 bool "AMD Secure Memory Encryption (SME) support"
1541 depends on X86_64 && CPU_SUP_AMD
1543 select DMA_COHERENT_POOL
1544 select ARCH_USE_MEMREMAP_PROT
1545 select INSTRUCTION_DECODER
1546 select ARCH_HAS_CC_PLATFORM
1547 select X86_MEM_ENCRYPT
1548 select UNACCEPTED_MEMORY
1550 Say yes to enable support for the encryption of system memory.
1551 This requires an AMD processor that supports Secure Memory
1554 # Common NUMA Features
1556 bool "NUMA Memory Allocation and Scheduler Support"
1558 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1559 default y if X86_BIGSMP
1560 select USE_PERCPU_NUMA_NODE_ID
1561 select OF_NUMA if OF
1563 Enable NUMA (Non-Uniform Memory Access) support.
1565 The kernel will try to allocate memory used by a CPU on the
1566 local memory controller of the CPU and add some more
1567 NUMA awareness to the kernel.
1569 For 64-bit this is recommended if the system is Intel Core i7
1570 (or later), AMD Opteron, or EM64T NUMA.
1572 For 32-bit this is only needed if you boot a 32-bit
1573 kernel on a 64-bit NUMA platform.
1575 Otherwise, you should say N.
1579 prompt "Old style AMD Opteron NUMA detection"
1580 depends on X86_64 && NUMA && PCI
1582 Enable AMD NUMA node topology detection. You should say Y here if
1583 you have a multi processor AMD system. This uses an old method to
1584 read the NUMA configuration directly from the builtin Northbridge
1585 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1586 which also takes priority if both are compiled in.
1588 config X86_64_ACPI_NUMA
1590 prompt "ACPI NUMA detection"
1591 depends on X86_64 && NUMA && ACPI && PCI
1594 Enable ACPI SRAT based node topology detection.
1597 bool "NUMA emulation"
1600 Enable NUMA emulation. A flat machine will be split
1601 into virtual nodes when booted with "numa=fake=N", where N is the
1602 number of nodes. This is only useful for debugging.
1605 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1607 default "10" if MAXSMP
1608 default "6" if X86_64
1612 Specify the maximum number of NUMA Nodes available on the target
1613 system. Increases memory reserved to accommodate various tables.
1615 config ARCH_FLATMEM_ENABLE
1617 depends on X86_32 && !NUMA
1619 config ARCH_SPARSEMEM_ENABLE
1621 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1622 select SPARSEMEM_STATIC if X86_32
1623 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1625 config ARCH_SPARSEMEM_DEFAULT
1626 def_bool X86_64 || (NUMA && X86_32)
1628 config ARCH_SELECT_MEMORY_MODEL
1630 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1632 config ARCH_MEMORY_PROBE
1633 bool "Enable sysfs memory/probe interface"
1634 depends on MEMORY_HOTPLUG
1636 This option enables a sysfs memory/probe interface for testing.
1637 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1638 If you are unsure how to answer this question, answer N.
1640 config ARCH_PROC_KCORE_TEXT
1642 depends on X86_64 && PROC_KCORE
1644 config ILLEGAL_POINTER_VALUE
1647 default 0xdead000000000000 if X86_64
1649 config X86_PMEM_LEGACY_DEVICE
1652 config X86_PMEM_LEGACY
1653 tristate "Support non-standard NVDIMMs and ADR protected memory"
1654 depends on PHYS_ADDR_T_64BIT
1656 select X86_PMEM_LEGACY_DEVICE
1657 select NUMA_KEEP_MEMINFO if NUMA
1660 Treat memory marked using the non-standard e820 type of 12 as used
1661 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1662 The kernel will offer these regions to the 'pmem' driver so
1663 they can be used for persistent storage.
1668 bool "Allocate 3rd-level pagetables from highmem"
1671 The VM uses one page table entry for each page of physical memory.
1672 For systems with a lot of RAM, this can be wasteful of precious
1673 low memory. Setting this option will put user-space page table
1674 entries in high memory.
1676 config X86_CHECK_BIOS_CORRUPTION
1677 bool "Check for low memory corruption"
1679 Periodically check for memory corruption in low memory, which
1680 is suspected to be caused by BIOS. Even when enabled in the
1681 configuration, it is disabled at runtime. Enable it by
1682 setting "memory_corruption_check=1" on the kernel command
1683 line. By default it scans the low 64k of memory every 60
1684 seconds; see the memory_corruption_check_size and
1685 memory_corruption_check_period parameters in
1686 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1688 When enabled with the default parameters, this option has
1689 almost no overhead, as it reserves a relatively small amount
1690 of memory and scans it infrequently. It both detects corruption
1691 and prevents it from affecting the running system.
1693 It is, however, intended as a diagnostic tool; if repeatable
1694 BIOS-originated corruption always affects the same memory,
1695 you can use memmap= to prevent the kernel from using that
1698 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1699 bool "Set the default setting of memory_corruption_check"
1700 depends on X86_CHECK_BIOS_CORRUPTION
1703 Set whether the default state of memory_corruption_check is
1706 config MATH_EMULATION
1708 depends on MODIFY_LDT_SYSCALL
1709 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1711 Linux can emulate a math coprocessor (used for floating point
1712 operations) if you don't have one. 486DX and Pentium processors have
1713 a math coprocessor built in, 486SX and 386 do not, unless you added
1714 a 487DX or 387, respectively. (The messages during boot time can
1715 give you some hints here ["man dmesg"].) Everyone needs either a
1716 coprocessor or this emulation.
1718 If you don't have a math coprocessor, you need to say Y here; if you
1719 say Y here even though you have a coprocessor, the coprocessor will
1720 be used nevertheless. (This behavior can be changed with the kernel
1721 command line option "no387", which comes handy if your coprocessor
1722 is broken. Try "man bootparam" or see the documentation of your boot
1723 loader (lilo or loadlin) about how to pass options to the kernel at
1724 boot time.) This means that it is a good idea to say Y here if you
1725 intend to use this kernel on different machines.
1727 More information about the internals of the Linux math coprocessor
1728 emulation can be found in <file:arch/x86/math-emu/README>.
1730 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1731 kernel, it won't hurt.
1735 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1737 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1738 the Memory Type Range Registers (MTRRs) may be used to control
1739 processor access to memory ranges. This is most useful if you have
1740 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1741 allows bus write transfers to be combined into a larger transfer
1742 before bursting over the PCI/AGP bus. This can increase performance
1743 of image write operations 2.5 times or more. Saying Y here creates a
1744 /proc/mtrr file which may be used to manipulate your processor's
1745 MTRRs. Typically the X server should use this.
1747 This code has a reasonably generic interface so that similar
1748 control registers on other processors can be easily supported
1751 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1752 Registers (ARRs) which provide a similar functionality to MTRRs. For
1753 these, the ARRs are used to emulate the MTRRs.
1754 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1755 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1756 write-combining. All of these processors are supported by this code
1757 and it makes sense to say Y here if you have one of them.
1759 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1760 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1761 can lead to all sorts of problems, so it's good to say Y here.
1763 You can safely say Y even if your machine doesn't have MTRRs, you'll
1764 just add about 9 KB to your kernel.
1766 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1768 config MTRR_SANITIZER
1770 prompt "MTRR cleanup support"
1773 Convert MTRR layout from continuous to discrete, so X drivers can
1774 add writeback entries.
1776 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1777 The largest mtrr entry size for a continuous block can be set with
1782 config MTRR_SANITIZER_ENABLE_DEFAULT
1783 int "MTRR cleanup enable value (0-1)"
1786 depends on MTRR_SANITIZER
1788 Enable mtrr cleanup default value
1790 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1791 int "MTRR cleanup spare reg num (0-7)"
1794 depends on MTRR_SANITIZER
1796 mtrr cleanup spare entries default, it can be changed via
1797 mtrr_spare_reg_nr=N on the kernel command line.
1801 prompt "x86 PAT support" if EXPERT
1804 Use PAT attributes to setup page level cache control.
1806 PATs are the modern equivalents of MTRRs and are much more
1807 flexible than MTRRs.
1809 Say N here if you see bootup problems (boot crash, boot hang,
1810 spontaneous reboots) or a non-working video driver.
1814 config ARCH_USES_PG_UNCACHED
1820 prompt "User Mode Instruction Prevention" if EXPERT
1822 User Mode Instruction Prevention (UMIP) is a security feature in
1823 some x86 processors. If enabled, a general protection fault is
1824 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1825 executed in user mode. These instructions unnecessarily expose
1826 information about the hardware state.
1828 The vast majority of applications do not use these instructions.
1829 For the very few that do, software emulation is provided in
1830 specific cases in protected and virtual-8086 modes. Emulated
1834 # GCC >= 9 and binutils >= 2.29
1835 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1837 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1838 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1839 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1840 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1846 CET features configured (Shadow stack or IBT)
1848 config X86_KERNEL_IBT
1849 prompt "Indirect Branch Tracking"
1851 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1852 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1853 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1857 Build the kernel with support for Indirect Branch Tracking, a
1858 hardware support course-grain forward-edge Control Flow Integrity
1859 protection. It enforces that all indirect calls must land on
1860 an ENDBR instruction, as such, the compiler will instrument the
1861 code with them to make this happen.
1863 In addition to building the kernel with IBT, seal all functions that
1864 are not indirect call targets, avoiding them ever becoming one.
1866 This requires LTO like objtool runs and will slow down the build. It
1867 does significantly reduce the number of ENDBR instructions in the
1870 config X86_INTEL_MEMORY_PROTECTION_KEYS
1871 prompt "Memory Protection Keys"
1873 # Note: only available in 64-bit mode
1874 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1875 select ARCH_USES_HIGH_VMA_FLAGS
1876 select ARCH_HAS_PKEYS
1878 Memory Protection Keys provides a mechanism for enforcing
1879 page-based protections, but without requiring modification of the
1880 page tables when an application changes protection domains.
1882 For details, see Documentation/core-api/protection-keys.rst
1887 prompt "TSX enable mode"
1888 depends on CPU_SUP_INTEL
1889 default X86_INTEL_TSX_MODE_OFF
1891 Intel's TSX (Transactional Synchronization Extensions) feature
1892 allows to optimize locking protocols through lock elision which
1893 can lead to a noticeable performance boost.
1895 On the other hand it has been shown that TSX can be exploited
1896 to form side channel attacks (e.g. TAA) and chances are there
1897 will be more of those attacks discovered in the future.
1899 Therefore TSX is not enabled by default (aka tsx=off). An admin
1900 might override this decision by tsx=on the command line parameter.
1901 Even with TSX enabled, the kernel will attempt to enable the best
1902 possible TAA mitigation setting depending on the microcode available
1903 for the particular machine.
1905 This option allows to set the default tsx mode between tsx=on, =off
1906 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1909 Say off if not sure, auto if TSX is in use but it should be used on safe
1910 platforms or on if TSX is in use and the security aspect of tsx is not
1913 config X86_INTEL_TSX_MODE_OFF
1916 TSX is disabled if possible - equals to tsx=off command line parameter.
1918 config X86_INTEL_TSX_MODE_ON
1921 TSX is always enabled on TSX capable HW - equals the tsx=on command
1924 config X86_INTEL_TSX_MODE_AUTO
1927 TSX is enabled on TSX capable HW that is believed to be safe against
1928 side channel attacks- equals the tsx=auto command line parameter.
1932 bool "Software Guard eXtensions (SGX)"
1933 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1935 depends on CRYPTO_SHA256=y
1937 select NUMA_KEEP_MEMINFO if NUMA
1940 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1941 that can be used by applications to set aside private regions of code
1942 and data, referred to as enclaves. An enclave's private memory can
1943 only be accessed by code running within the enclave. Accesses from
1944 outside the enclave, including other enclaves, are disallowed by
1949 config X86_USER_SHADOW_STACK
1950 bool "X86 userspace shadow stack"
1953 select ARCH_USES_HIGH_VMA_FLAGS
1956 Shadow stack protection is a hardware feature that detects function
1957 return address corruption. This helps mitigate ROP attacks.
1958 Applications must be enabled to use it, and old userspace does not
1959 get protection "for free".
1961 CPUs supporting shadow stacks were first released in 2020.
1963 See Documentation/arch/x86/shstk.rst for more information.
1967 config INTEL_TDX_HOST
1968 bool "Intel Trust Domain Extensions (TDX) host support"
1969 depends on CPU_SUP_INTEL
1971 depends on KVM_INTEL
1972 depends on X86_X2APIC
1973 select ARCH_KEEP_MEMBLOCK
1974 depends on CONTIG_ALLOC
1975 depends on !KEXEC_CORE
1978 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1979 host and certain physical attacks. This option enables necessary TDX
1980 support in the host kernel to run confidential VMs.
1985 bool "EFI runtime service support"
1988 select EFI_RUNTIME_WRAPPERS
1989 select ARCH_USE_MEMREMAP_PROT
1990 select EFI_RUNTIME_MAP if KEXEC_CORE
1992 This enables the kernel to use EFI runtime services that are
1993 available (such as the EFI variable services).
1995 This option is only useful on systems that have EFI firmware.
1996 In addition, you should use the latest ELILO loader available
1997 at <http://elilo.sourceforge.net> in order to take advantage
1998 of EFI runtime services. However, even with this option, the
1999 resultant kernel should continue to boot on existing non-EFI
2003 bool "EFI stub support"
2007 This kernel feature allows a bzImage to be loaded directly
2008 by EFI firmware without the use of a bootloader.
2010 See Documentation/admin-guide/efi-stub.rst for more information.
2012 config EFI_HANDOVER_PROTOCOL
2013 bool "EFI handover protocol (DEPRECATED)"
2017 Select this in order to include support for the deprecated EFI
2018 handover protocol, which defines alternative entry points into the
2019 EFI stub. This is a practice that has no basis in the UEFI
2020 specification, and requires a priori knowledge on the part of the
2021 bootloader about Linux/x86 specific ways of passing the command line
2022 and initrd, and where in memory those assets may be loaded.
2024 If in doubt, say Y. Even though the corresponding support is not
2025 present in upstream GRUB or other bootloaders, most distros build
2026 GRUB with numerous downstream patches applied, and may rely on the
2027 handover protocol as as result.
2030 bool "EFI mixed-mode support"
2031 depends on EFI_STUB && X86_64
2033 Enabling this feature allows a 64-bit kernel to be booted
2034 on a 32-bit firmware, provided that your CPU supports 64-bit
2037 Note that it is not possible to boot a mixed-mode enabled
2038 kernel via the EFI boot stub - a bootloader that supports
2039 the EFI handover protocol must be used.
2043 config EFI_FAKE_MEMMAP
2044 bool "Enable EFI fake memory map"
2047 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2048 this parameter, you can add arbitrary attribute to specific memory
2049 range by updating original (firmware provided) EFI memmap. This is
2050 useful for debugging of EFI memmap related feature, e.g., Address
2051 Range Mirroring feature.
2053 config EFI_MAX_FAKE_MEM
2054 int "maximum allowable number of ranges in efi_fake_mem boot option"
2055 depends on EFI_FAKE_MEMMAP
2059 Maximum allowable number of ranges in efi_fake_mem boot option.
2060 Ranges can be set up to this value using comma-separated list.
2061 The default value is 8.
2063 config EFI_RUNTIME_MAP
2064 bool "Export EFI runtime maps to sysfs" if EXPERT
2067 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2068 That memory map is required by the 2nd kernel to set up EFI virtual
2069 mappings after kexec, but can also be used for debugging purposes.
2071 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2073 source "kernel/Kconfig.hz"
2075 config ARCH_SUPPORTS_KEXEC
2078 config ARCH_SUPPORTS_KEXEC_FILE
2081 config ARCH_SELECTS_KEXEC_FILE
2083 depends on KEXEC_FILE
2084 select HAVE_IMA_KEXEC if IMA
2086 config ARCH_SUPPORTS_KEXEC_PURGATORY
2089 config ARCH_SUPPORTS_KEXEC_SIG
2092 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2095 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2098 config ARCH_SUPPORTS_KEXEC_JUMP
2101 config ARCH_SUPPORTS_CRASH_DUMP
2102 def_bool X86_64 || (X86_32 && HIGHMEM)
2104 config ARCH_SUPPORTS_CRASH_HOTPLUG
2107 config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2110 config PHYSICAL_START
2111 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2114 This gives the physical address where the kernel is loaded.
2116 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2117 will decompress itself to above physical address and run from there.
2118 Otherwise, bzImage will run from the address where it has been loaded
2119 by the boot loader. The only exception is if it is loaded below the
2120 above physical address, in which case it will relocate itself there.
2122 In normal kdump cases one does not have to set/change this option
2123 as now bzImage can be compiled as a completely relocatable image
2124 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2125 address. This option is mainly useful for the folks who don't want
2126 to use a bzImage for capturing the crash dump and want to use a
2127 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2128 to be specifically compiled to run from a specific memory area
2129 (normally a reserved region) and this option comes handy.
2131 So if you are using bzImage for capturing the crash dump,
2132 leave the value here unchanged to 0x1000000 and set
2133 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2134 for capturing the crash dump change this value to start of
2135 the reserved region. In other words, it can be set based on
2136 the "X" value as specified in the "crashkernel=YM@XM"
2137 command line boot parameter passed to the panic-ed
2138 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2139 for more details about crash dumps.
2141 Usage of bzImage for capturing the crash dump is recommended as
2142 one does not have to build two kernels. Same kernel can be used
2143 as production kernel and capture kernel. Above option should have
2144 gone away after relocatable bzImage support is introduced. But it
2145 is present because there are users out there who continue to use
2146 vmlinux for dump capture. This option should go away down the
2149 Don't change this unless you know what you are doing.
2152 bool "Build a relocatable kernel"
2155 This builds a kernel image that retains relocation information
2156 so it can be loaded someplace besides the default 1MB.
2157 The relocations tend to make the kernel binary about 10% larger,
2158 but are discarded at runtime.
2160 One use is for the kexec on panic case where the recovery kernel
2161 must live at a different physical address than the primary
2164 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2165 it has been loaded at and the compile time physical address
2166 (CONFIG_PHYSICAL_START) is used as the minimum location.
2168 config RANDOMIZE_BASE
2169 bool "Randomize the address of the kernel image (KASLR)"
2170 depends on RELOCATABLE
2173 In support of Kernel Address Space Layout Randomization (KASLR),
2174 this randomizes the physical address at which the kernel image
2175 is decompressed and the virtual address where the kernel
2176 image is mapped, as a security feature that deters exploit
2177 attempts relying on knowledge of the location of kernel
2180 On 64-bit, the kernel physical and virtual addresses are
2181 randomized separately. The physical address will be anywhere
2182 between 16MB and the top of physical memory (up to 64TB). The
2183 virtual address will be randomized from 16MB up to 1GB (9 bits
2184 of entropy). Note that this also reduces the memory space
2185 available to kernel modules from 1.5GB to 1GB.
2187 On 32-bit, the kernel physical and virtual addresses are
2188 randomized together. They will be randomized from 16MB up to
2189 512MB (8 bits of entropy).
2191 Entropy is generated using the RDRAND instruction if it is
2192 supported. If RDTSC is supported, its value is mixed into
2193 the entropy pool as well. If neither RDRAND nor RDTSC are
2194 supported, then entropy is read from the i8254 timer. The
2195 usable entropy is limited by the kernel being built using
2196 2GB addressing, and that PHYSICAL_ALIGN must be at a
2197 minimum of 2MB. As a result, only 10 bits of entropy are
2198 theoretically possible, but the implementations are further
2199 limited due to memory layouts.
2203 # Relocation on x86 needs some additional build support
2204 config X86_NEED_RELOCS
2206 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2208 config PHYSICAL_ALIGN
2209 hex "Alignment value to which kernel should be aligned"
2211 range 0x2000 0x1000000 if X86_32
2212 range 0x200000 0x1000000 if X86_64
2214 This value puts the alignment restrictions on physical address
2215 where kernel is loaded and run from. Kernel is compiled for an
2216 address which meets above alignment restriction.
2218 If bootloader loads the kernel at a non-aligned address and
2219 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2220 address aligned to above value and run from there.
2222 If bootloader loads the kernel at a non-aligned address and
2223 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2224 load address and decompress itself to the address it has been
2225 compiled for and run from there. The address for which kernel is
2226 compiled already meets above alignment restrictions. Hence the
2227 end result is that kernel runs from a physical address meeting
2228 above alignment restrictions.
2230 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2231 this value must be a multiple of 0x200000.
2233 Don't change this unless you know what you are doing.
2235 config DYNAMIC_MEMORY_LAYOUT
2238 This option makes base addresses of vmalloc and vmemmap as well as
2239 __PAGE_OFFSET movable during boot.
2241 config RANDOMIZE_MEMORY
2242 bool "Randomize the kernel memory sections"
2244 depends on RANDOMIZE_BASE
2245 select DYNAMIC_MEMORY_LAYOUT
2246 default RANDOMIZE_BASE
2248 Randomizes the base virtual address of kernel memory sections
2249 (physical memory mapping, vmalloc & vmemmap). This security feature
2250 makes exploits relying on predictable memory locations less reliable.
2252 The order of allocations remains unchanged. Entropy is generated in
2253 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2254 configuration have in average 30,000 different possible virtual
2255 addresses for each memory section.
2259 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2260 hex "Physical memory mapping padding" if EXPERT
2261 depends on RANDOMIZE_MEMORY
2262 default "0xa" if MEMORY_HOTPLUG
2264 range 0x1 0x40 if MEMORY_HOTPLUG
2267 Define the padding in terabytes added to the existing physical
2268 memory size during kernel memory randomization. It is useful
2269 for memory hotplug support but reduces the entropy available for
2270 address randomization.
2272 If unsure, leave at the default value.
2274 config ADDRESS_MASKING
2275 bool "Linear Address Masking support"
2278 Linear Address Masking (LAM) modifies the checking that is applied
2279 to 64-bit linear addresses, allowing software to use of the
2280 untranslated address bits for metadata.
2282 The capability can be used for efficient address sanitizers (ASAN)
2283 implementation and for optimizations in JITs.
2291 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2292 depends on COMPAT_32
2294 Certain buggy versions of glibc will crash if they are
2295 presented with a 32-bit vDSO that is not mapped at the address
2296 indicated in its segment table.
2298 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2299 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2300 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2301 the only released version with the bug, but OpenSUSE 9
2302 contains a buggy "glibc 2.3.2".
2304 The symptom of the bug is that everything crashes on startup, saying:
2305 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2307 Saying Y here changes the default value of the vdso32 boot
2308 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2309 This works around the glibc bug but hurts performance.
2311 If unsure, say N: if you are compiling your own kernel, you
2312 are unlikely to be using a buggy version of glibc.
2315 prompt "vsyscall table for legacy applications"
2317 default LEGACY_VSYSCALL_XONLY
2319 Legacy user code that does not know how to find the vDSO expects
2320 to be able to issue three syscalls by calling fixed addresses in
2321 kernel space. Since this location is not randomized with ASLR,
2322 it can be used to assist security vulnerability exploitation.
2324 This setting can be changed at boot time via the kernel command
2325 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2326 is deprecated and can only be enabled using the kernel command
2329 On a system with recent enough glibc (2.14 or newer) and no
2330 static binaries, you can say None without a performance penalty
2331 to improve security.
2333 If unsure, select "Emulate execution only".
2335 config LEGACY_VSYSCALL_XONLY
2336 bool "Emulate execution only"
2338 The kernel traps and emulates calls into the fixed vsyscall
2339 address mapping and does not allow reads. This
2340 configuration is recommended when userspace might use the
2341 legacy vsyscall area but support for legacy binary
2342 instrumentation of legacy code is not needed. It mitigates
2343 certain uses of the vsyscall area as an ASLR-bypassing
2346 config LEGACY_VSYSCALL_NONE
2349 There will be no vsyscall mapping at all. This will
2350 eliminate any risk of ASLR bypass due to the vsyscall
2351 fixed address mapping. Attempts to use the vsyscalls
2352 will be reported to dmesg, so that either old or
2353 malicious userspace programs can be identified.
2358 bool "Built-in kernel command line"
2360 Allow for specifying boot arguments to the kernel at
2361 build time. On some systems (e.g. embedded ones), it is
2362 necessary or convenient to provide some or all of the
2363 kernel boot arguments with the kernel itself (that is,
2364 to not rely on the boot loader to provide them.)
2366 To compile command line arguments into the kernel,
2367 set this option to 'Y', then fill in the
2368 boot arguments in CONFIG_CMDLINE.
2370 Systems with fully functional boot loaders (i.e. non-embedded)
2371 should leave this option set to 'N'.
2374 string "Built-in kernel command string"
2375 depends on CMDLINE_BOOL
2378 Enter arguments here that should be compiled into the kernel
2379 image and used at boot time. If the boot loader provides a
2380 command line at boot time, it is appended to this string to
2381 form the full kernel command line, when the system boots.
2383 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2384 change this behavior.
2386 In most cases, the command line (whether built-in or provided
2387 by the boot loader) should specify the device for the root
2390 config CMDLINE_OVERRIDE
2391 bool "Built-in command line overrides boot loader arguments"
2392 depends on CMDLINE_BOOL && CMDLINE != ""
2394 Set this option to 'Y' to have the kernel ignore the boot loader
2395 command line, and use ONLY the built-in command line.
2397 This is used to work around broken boot loaders. This should
2398 be set to 'N' under normal conditions.
2400 config MODIFY_LDT_SYSCALL
2401 bool "Enable the LDT (local descriptor table)" if EXPERT
2404 Linux can allow user programs to install a per-process x86
2405 Local Descriptor Table (LDT) using the modify_ldt(2) system
2406 call. This is required to run 16-bit or segmented code such as
2407 DOSEMU or some Wine programs. It is also used by some very old
2408 threading libraries.
2410 Enabling this feature adds a small amount of overhead to
2411 context switches and increases the low-level kernel attack
2412 surface. Disabling it removes the modify_ldt(2) system call.
2414 Saying 'N' here may make sense for embedded or server kernels.
2416 config STRICT_SIGALTSTACK_SIZE
2417 bool "Enforce strict size checking for sigaltstack"
2418 depends on DYNAMIC_SIGFRAME
2420 For historical reasons MINSIGSTKSZ is a constant which became
2421 already too small with AVX512 support. Add a mechanism to
2422 enforce strict checking of the sigaltstack size against the
2423 real size of the FPU frame. This option enables the check
2424 by default. It can also be controlled via the kernel command
2425 line option 'strict_sas_size' independent of this config
2426 switch. Enabling it might break existing applications which
2427 allocate a too small sigaltstack but 'work' because they
2428 never get a signal delivered.
2430 Say 'N' unless you want to really enforce this check.
2432 source "kernel/livepatch/Kconfig"
2436 config CC_HAS_NAMED_AS
2437 def_bool CC_IS_GCC && GCC_VERSION >= 120100
2439 config USE_X86_SEG_SUPPORT
2441 depends on CC_HAS_NAMED_AS
2443 # -fsanitize=kernel-address (KASAN) is at the moment incompatible
2444 # with named address spaces - see GCC PR sanitizer/111736.
2449 def_bool $(cc-option,-mharden-sls=all)
2451 config CC_HAS_RETURN_THUNK
2452 def_bool $(cc-option,-mfunction-return=thunk-extern)
2454 config CC_HAS_ENTRY_PADDING
2455 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2457 config FUNCTION_PADDING_CFI
2459 default 59 if FUNCTION_ALIGNMENT_64B
2460 default 27 if FUNCTION_ALIGNMENT_32B
2461 default 11 if FUNCTION_ALIGNMENT_16B
2462 default 3 if FUNCTION_ALIGNMENT_8B
2465 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2466 # except Kconfig can't do arithmetic :/
2467 config FUNCTION_PADDING_BYTES
2469 default FUNCTION_PADDING_CFI if CFI_CLANG
2470 default FUNCTION_ALIGNMENT
2474 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2475 select FUNCTION_ALIGNMENT_16B
2479 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2482 config HAVE_CALL_THUNKS
2484 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2490 config PREFIX_SYMBOLS
2492 depends on CALL_PADDING && !CFI_CLANG
2494 menuconfig SPECULATION_MITIGATIONS
2495 bool "Mitigations for speculative execution vulnerabilities"
2498 Say Y here to enable options which enable mitigations for
2499 speculative execution hardware vulnerabilities.
2501 If you say N, all mitigations will be disabled. You really
2502 should know what you are doing to say so.
2504 if SPECULATION_MITIGATIONS
2506 config MITIGATION_PAGE_TABLE_ISOLATION
2507 bool "Remove the kernel mapping in user mode"
2509 depends on (X86_64 || X86_PAE)
2511 This feature reduces the number of hardware side channels by
2512 ensuring that the majority of kernel addresses are not mapped
2515 See Documentation/arch/x86/pti.rst for more details.
2517 config MITIGATION_RETPOLINE
2518 bool "Avoid speculative indirect branches in kernel"
2519 select OBJTOOL if HAVE_OBJTOOL
2522 Compile kernel with the retpoline compiler options to guard against
2523 kernel-to-user data leaks by avoiding speculative indirect
2524 branches. Requires a compiler with -mindirect-branch=thunk-extern
2525 support for full protection. The kernel may run slower.
2527 config MITIGATION_RETHUNK
2528 bool "Enable return-thunks"
2529 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2530 select OBJTOOL if HAVE_OBJTOOL
2533 Compile the kernel with the return-thunks compiler option to guard
2534 against kernel-to-user data leaks by avoiding return speculation.
2535 Requires a compiler with -mfunction-return=thunk-extern
2536 support for full protection. The kernel may run slower.
2538 config MITIGATION_UNRET_ENTRY
2539 bool "Enable UNRET on kernel entry"
2540 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2543 Compile the kernel with support for the retbleed=unret mitigation.
2545 config MITIGATION_CALL_DEPTH_TRACKING
2546 bool "Mitigate RSB underflow with call depth tracking"
2547 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2548 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2552 Compile the kernel with call depth tracking to mitigate the Intel
2553 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2554 mitigation is off by default and needs to be enabled on the
2555 kernel command line via the retbleed=stuff option. For
2556 non-affected systems the overhead of this option is marginal as
2557 the call depth tracking is using run-time generated call thunks
2558 in a compiler generated padding area and call patching. This
2559 increases text size by ~5%. For non affected systems this space
2560 is unused. On affected SKL systems this results in a significant
2561 performance gain over the IBRS mitigation.
2563 config CALL_THUNKS_DEBUG
2564 bool "Enable call thunks and call depth tracking debugging"
2565 depends on MITIGATION_CALL_DEPTH_TRACKING
2566 select FUNCTION_ALIGNMENT_32B
2569 Enable call/ret counters for imbalance detection and build in
2570 a noisy dmesg about callthunks generation and call patching for
2571 trouble shooting. The debug prints need to be enabled on the
2572 kernel command line with 'debug-callthunks'.
2573 Only enable this when you are debugging call thunks as this
2574 creates a noticeable runtime overhead. If unsure say N.
2576 config MITIGATION_IBPB_ENTRY
2577 bool "Enable IBPB on kernel entry"
2578 depends on CPU_SUP_AMD && X86_64
2581 Compile the kernel with support for the retbleed=ibpb mitigation.
2583 config MITIGATION_IBRS_ENTRY
2584 bool "Enable IBRS on kernel entry"
2585 depends on CPU_SUP_INTEL && X86_64
2588 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2589 This mitigates both spectre_v2 and retbleed at great cost to
2592 config MITIGATION_SRSO
2593 bool "Mitigate speculative RAS overflow on AMD"
2594 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2597 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2599 config MITIGATION_SLS
2600 bool "Mitigate Straight-Line-Speculation"
2601 depends on CC_HAS_SLS && X86_64
2602 select OBJTOOL if HAVE_OBJTOOL
2605 Compile the kernel with straight-line-speculation options to guard
2606 against straight line speculation. The kernel image might be slightly
2609 config MITIGATION_GDS_FORCE
2610 bool "Force GDS Mitigation"
2611 depends on CPU_SUP_INTEL
2614 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2615 unprivileged speculative access to data which was previously stored in
2618 This option is equivalent to setting gather_data_sampling=force on the
2619 command line. The microcode mitigation is used if present, otherwise
2620 AVX is disabled as a mitigation. On affected systems that are missing
2621 the microcode any userspace code that unconditionally uses AVX will
2622 break with this option set.
2624 Setting this option on systems not vulnerable to GDS has no effect.
2628 config MITIGATION_RFDS
2629 bool "RFDS Mitigation"
2630 depends on CPU_SUP_INTEL
2633 Enable mitigation for Register File Data Sampling (RFDS) by default.
2634 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2635 allows unprivileged speculative access to stale data previously
2636 stored in floating point, vector and integer registers.
2637 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.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"