1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_SUPPORTS_PER_VMA_LOCK
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
63 select ARCH_32BIT_OFF_T if X86_32
64 select ARCH_CLOCKSOURCE_INIT
65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
72 select ARCH_HAS_CACHE_LINE_SIZE
73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
74 select ARCH_HAS_CPU_FINALIZE_INIT
75 select ARCH_HAS_CPU_PASID if IOMMU_SVA
76 select ARCH_HAS_CURRENT_STACK_POINTER
77 select ARCH_HAS_DEBUG_VIRTUAL
78 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
79 select ARCH_HAS_DEVMEM_IS_ALLOWED
80 select ARCH_HAS_EARLY_DEBUG if KGDB
81 select ARCH_HAS_ELF_RANDOMIZE
82 select ARCH_HAS_FAST_MULTIPLIER
83 select ARCH_HAS_FORTIFY_SOURCE
84 select ARCH_HAS_GCOV_PROFILE_ALL
85 select ARCH_HAS_KCOV if X86_64
86 select ARCH_HAS_MEM_ENCRYPT
87 select ARCH_HAS_MEMBARRIER_SYNC_CORE
88 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
89 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
90 select ARCH_HAS_PMEM_API if X86_64
91 select ARCH_HAS_PTE_DEVMAP if X86_64
92 select ARCH_HAS_PTE_SPECIAL
93 select ARCH_HAS_HW_PTE_YOUNG
94 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
95 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
96 select ARCH_HAS_COPY_MC if X86_64
97 select ARCH_HAS_SET_MEMORY
98 select ARCH_HAS_SET_DIRECT_MAP
99 select ARCH_HAS_STRICT_KERNEL_RWX
100 select ARCH_HAS_STRICT_MODULE_RWX
101 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
102 select ARCH_HAS_SYSCALL_WRAPPER
103 select ARCH_HAS_UBSAN_SANITIZE_ALL
104 select ARCH_HAS_DEBUG_WX
105 select ARCH_HAS_ZONE_DMA_SET if EXPERT
106 select ARCH_HAVE_NMI_SAFE_CMPXCHG
107 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
108 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
109 select ARCH_MIGHT_HAVE_PC_PARPORT
110 select ARCH_MIGHT_HAVE_PC_SERIO
111 select ARCH_STACKWALK
112 select ARCH_SUPPORTS_ACPI
113 select ARCH_SUPPORTS_ATOMIC_RMW
114 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
115 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
116 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
117 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
118 select ARCH_SUPPORTS_CFI_CLANG if X86_64
119 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
120 select ARCH_SUPPORTS_LTO_CLANG
121 select ARCH_SUPPORTS_LTO_CLANG_THIN
122 select ARCH_USE_BUILTIN_BSWAP
123 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
124 select ARCH_USE_MEMTEST
125 select ARCH_USE_QUEUED_RWLOCKS
126 select ARCH_USE_QUEUED_SPINLOCKS
127 select ARCH_USE_SYM_ANNOTATIONS
128 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
129 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
130 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
131 select ARCH_WANTS_NO_INSTR
132 select ARCH_WANT_GENERAL_HUGETLB
133 select ARCH_WANT_HUGE_PMD_SHARE
134 select ARCH_WANT_LD_ORPHAN_WARN
135 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
136 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
137 select ARCH_WANTS_THP_SWAP if X86_64
138 select ARCH_HAS_PARANOID_L1D_FLUSH
139 select BUILDTIME_TABLE_SORT
141 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
142 select CLOCKSOURCE_WATCHDOG
143 # Word-size accesses may read uninitialized data past the trailing \0
144 # in strings and cause false KMSAN reports.
145 select DCACHE_WORD_ACCESS if !KMSAN
146 select DYNAMIC_SIGFRAME
147 select EDAC_ATOMIC_SCRUB
149 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
150 select GENERIC_CLOCKEVENTS_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_PCSPKR_PLATFORM
260 select HAVE_PERF_EVENTS
261 select HAVE_PERF_EVENTS_NMI
262 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
264 select HAVE_PERF_REGS
265 select HAVE_PERF_USER_STACK_DUMP
266 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
267 select MMU_GATHER_MERGE_VMAS
268 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
269 select HAVE_REGS_AND_STACK_ACCESS_API
270 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
271 select HAVE_FUNCTION_ARG_ACCESS_API
272 select HAVE_SETUP_PER_CPU_AREA
273 select HAVE_SOFTIRQ_ON_OWN_STACK
274 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
275 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
276 select HAVE_STATIC_CALL
277 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
278 select HAVE_PREEMPT_DYNAMIC_CALL
280 select HAVE_RUST if X86_64
281 select HAVE_SYSCALL_TRACEPOINTS
282 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
283 select HAVE_UNSTABLE_SCHED_CLOCK
284 select HAVE_USER_RETURN_NOTIFIER
285 select HAVE_GENERIC_VDSO
286 select HOTPLUG_PARALLEL if SMP && X86_64
287 select HOTPLUG_SMT if SMP
288 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
289 select IRQ_FORCED_THREADING
290 select LOCK_MM_AND_FIND_VMA
291 select NEED_PER_CPU_EMBED_FIRST_CHUNK
292 select NEED_PER_CPU_PAGE_FIRST_CHUNK
293 select NEED_SG_DMA_LENGTH
294 select PCI_DOMAINS if PCI
295 select PCI_LOCKLESS_CONFIG if PCI
298 select RTC_MC146818_LIB
300 select SYSCTL_EXCEPTION_TRACE
301 select THREAD_INFO_IN_TASK
302 select TRACE_IRQFLAGS_SUPPORT
303 select TRACE_IRQFLAGS_NMI_SUPPORT
304 select USER_STACKTRACE_SUPPORT
305 select HAVE_ARCH_KCSAN if X86_64
306 select PROC_PID_ARCH_STATUS if PROC_FS
307 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
308 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
309 select FUNCTION_ALIGNMENT_4B
310 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
311 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
313 config INSTRUCTION_DECODER
315 depends on KPROBES || PERF_EVENTS || UPROBES
319 default "elf32-i386" if X86_32
320 default "elf64-x86-64" if X86_64
322 config LOCKDEP_SUPPORT
325 config STACKTRACE_SUPPORT
331 config ARCH_MMAP_RND_BITS_MIN
335 config ARCH_MMAP_RND_BITS_MAX
339 config ARCH_MMAP_RND_COMPAT_BITS_MIN
342 config ARCH_MMAP_RND_COMPAT_BITS_MAX
348 config GENERIC_ISA_DMA
350 depends on ISA_DMA_API
354 default y if KMSAN || KASAN
359 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
361 config GENERIC_BUG_RELATIVE_POINTERS
364 config ARCH_MAY_HAVE_PC_FDC
366 depends on ISA_DMA_API
368 config GENERIC_CALIBRATE_DELAY
371 config ARCH_HAS_CPU_RELAX
374 config ARCH_HIBERNATION_POSSIBLE
377 config ARCH_SUSPEND_POSSIBLE
383 config KASAN_SHADOW_OFFSET
386 default 0xdffffc0000000000
388 config HAVE_INTEL_TXT
390 depends on INTEL_IOMMU && ACPI
394 depends on X86_64 && SMP
396 config ARCH_SUPPORTS_UPROBES
399 config FIX_EARLYCON_MEM
402 config DYNAMIC_PHYSICAL_MASK
405 config PGTABLE_LEVELS
407 default 5 if X86_5LEVEL
412 config CC_HAS_SANE_STACKPROTECTOR
414 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
415 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
417 We have to make sure stack protector is unconditionally disabled if
418 the compiler produces broken code or if it does not let us control
419 the segment on 32-bit kernels.
421 menu "Processor type and features"
424 bool "Symmetric multi-processing support"
426 This enables support for systems with more than one CPU. If you have
427 a system with only one CPU, say N. If you have a system with more
430 If you say N here, the kernel will run on uni- and multiprocessor
431 machines, but will use only one CPU of a multiprocessor machine. If
432 you say Y here, the kernel will run on many, but not all,
433 uniprocessor machines. On a uniprocessor machine, the kernel
434 will run faster if you say N here.
436 Note that if you say Y here and choose architecture "586" or
437 "Pentium" under "Processor family", the kernel will not work on 486
438 architectures. Similarly, multiprocessor kernels for the "PPro"
439 architecture may not work on all Pentium based boards.
441 People using multiprocessor machines who say Y here should also say
442 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
443 Management" code will be disabled if you say Y here.
445 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
446 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
447 <http://www.tldp.org/docs.html#howto>.
449 If you don't know what to do here, say N.
452 bool "Support x2apic"
453 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
455 This enables x2apic support on CPUs that have this feature.
457 This allows 32-bit apic IDs (so it can support very large systems),
458 and accesses the local apic via MSRs not via mmio.
460 Some Intel systems circa 2022 and later are locked into x2APIC mode
461 and can not fall back to the legacy APIC modes if SGX or TDX are
462 enabled in the BIOS. They will boot with very reduced functionality
463 without enabling this option.
465 If you don't know what to do here, say N.
468 bool "Enable MPS table" if ACPI
470 depends on X86_LOCAL_APIC
472 For old smp systems that do not have proper acpi support. Newer systems
473 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
477 depends on X86_GOLDFISH
479 config X86_CPU_RESCTRL
480 bool "x86 CPU resource control support"
481 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
483 select PROC_CPU_RESCTRL if PROC_FS
485 Enable x86 CPU resource control support.
487 Provide support for the allocation and monitoring of system resources
490 Intel calls this Intel Resource Director Technology
491 (Intel(R) RDT). More information about RDT can be found in the
492 Intel x86 Architecture Software Developer Manual.
494 AMD calls this AMD Platform Quality of Service (AMD QoS).
495 More information about AMD QoS can be found in the AMD64 Technology
496 Platform Quality of Service Extensions manual.
501 bool "Flexible Return and Event Delivery"
504 When enabled, try to use Flexible Return and Event Delivery
505 instead of the legacy SYSCALL/SYSENTER/IDT architecture for
506 ring transitions and exception/interrupt handling if the
511 bool "Support for big SMP systems with more than 8 CPUs"
514 This option is needed for the systems that have more than 8 CPUs.
516 config X86_EXTENDED_PLATFORM
517 bool "Support for extended (non-PC) x86 platforms"
520 If you disable this option then the kernel will only support
521 standard PC platforms. (which covers the vast majority of
524 If you enable this option then you'll be able to select support
525 for the following (non-PC) 32 bit x86 platforms:
526 Goldfish (Android emulator)
529 SGI 320/540 (Visual Workstation)
530 STA2X11-based (e.g. Northville)
531 Moorestown MID devices
533 If you have one of these systems, or if you want to build a
534 generic distribution kernel, say Y here - otherwise say N.
538 config X86_EXTENDED_PLATFORM
539 bool "Support for extended (non-PC) x86 platforms"
542 If you disable this option then the kernel will only support
543 standard PC platforms. (which covers the vast majority of
546 If you enable this option then you'll be able to select support
547 for the following (non-PC) 64 bit x86 platforms:
552 If you have one of these systems, or if you want to build a
553 generic distribution kernel, say Y here - otherwise say N.
555 # This is an alphabetically sorted list of 64 bit extended platforms
556 # Please maintain the alphabetic order if and when there are additions
558 bool "Numascale NumaChip"
560 depends on X86_EXTENDED_PLATFORM
563 depends on X86_X2APIC
564 depends on PCI_MMCONFIG
566 Adds support for Numascale NumaChip large-SMP systems. Needed to
567 enable more than ~168 cores.
568 If you don't have one of these, you should say N here.
572 select HYPERVISOR_GUEST
574 depends on X86_64 && PCI
575 depends on X86_EXTENDED_PLATFORM
578 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
579 supposed to run on these EM64T-based machines. Only choose this option
580 if you have one of these machines.
583 bool "SGI Ultraviolet"
585 depends on X86_EXTENDED_PLATFORM
588 depends on KEXEC_CORE
589 depends on X86_X2APIC
592 This option is needed in order to support SGI Ultraviolet systems.
593 If you don't have one of these, you should say N here.
595 # Following is an alphabetically sorted list of 32 bit extended platforms
596 # Please maintain the alphabetic order if and when there are additions
599 bool "Goldfish (Virtual Platform)"
600 depends on X86_EXTENDED_PLATFORM
602 Enable support for the Goldfish virtual platform used primarily
603 for Android development. Unless you are building for the Android
604 Goldfish emulator say N here.
607 bool "CE4100 TV platform"
609 depends on PCI_GODIRECT
610 depends on X86_IO_APIC
612 depends on X86_EXTENDED_PLATFORM
613 select X86_REBOOTFIXUPS
615 select OF_EARLY_FLATTREE
617 Select for the Intel CE media processor (CE4100) SOC.
618 This option compiles in support for the CE4100 SOC for settop
619 boxes and media devices.
622 bool "Intel MID platform support"
623 depends on X86_EXTENDED_PLATFORM
624 depends on X86_PLATFORM_DEVICES
626 depends on X86_64 || (PCI_GOANY && X86_32)
627 depends on X86_IO_APIC
632 Select to build a kernel capable of supporting Intel MID (Mobile
633 Internet Device) platform systems which do not have the PCI legacy
634 interfaces. If you are building for a PC class system say N here.
636 Intel MID platforms are based on an Intel processor and chipset which
637 consume less power than most of the x86 derivatives.
639 config X86_INTEL_QUARK
640 bool "Intel Quark platform support"
642 depends on X86_EXTENDED_PLATFORM
643 depends on X86_PLATFORM_DEVICES
647 depends on X86_IO_APIC
652 Select to include support for Quark X1000 SoC.
653 Say Y here if you have a Quark based system such as the Arduino
654 compatible Intel Galileo.
656 config X86_INTEL_LPSS
657 bool "Intel Low Power Subsystem Support"
658 depends on X86 && ACPI && PCI
663 Select to build support for Intel Low Power Subsystem such as
664 found on Intel Lynxpoint PCH. Selecting this option enables
665 things like clock tree (common clock framework) and pincontrol
666 which are needed by the LPSS peripheral drivers.
668 config X86_AMD_PLATFORM_DEVICE
669 bool "AMD ACPI2Platform devices support"
674 Select to interpret AMD specific ACPI device to platform device
675 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
676 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
677 implemented under PINCTRL subsystem.
680 tristate "Intel SoC IOSF Sideband support for SoC platforms"
683 This option enables sideband register access support for Intel SoC
684 platforms. On these platforms the IOSF sideband is used in lieu of
685 MSR's for some register accesses, mostly but not limited to thermal
686 and power. Drivers may query the availability of this device to
687 determine if they need the sideband in order to work on these
688 platforms. The sideband is available on the following SoC products.
689 This list is not meant to be exclusive.
694 You should say Y if you are running a kernel on one of these SoC's.
696 config IOSF_MBI_DEBUG
697 bool "Enable IOSF sideband access through debugfs"
698 depends on IOSF_MBI && DEBUG_FS
700 Select this option to expose the IOSF sideband access registers (MCR,
701 MDR, MCRX) through debugfs to write and read register information from
702 different units on the SoC. This is most useful for obtaining device
703 state information for debug and analysis. As this is a general access
704 mechanism, users of this option would have specific knowledge of the
705 device they want to access.
707 If you don't require the option or are in doubt, say N.
710 bool "RDC R-321x SoC"
712 depends on X86_EXTENDED_PLATFORM
714 select X86_REBOOTFIXUPS
716 This option is needed for RDC R-321x system-on-chip, also known
718 If you don't have one of these chips, you should say N here.
720 config X86_32_NON_STANDARD
721 bool "Support non-standard 32-bit SMP architectures"
722 depends on X86_32 && SMP
723 depends on X86_EXTENDED_PLATFORM
725 This option compiles in the bigsmp and STA2X11 default
726 subarchitectures. It is intended for a generic binary
727 kernel. If you select them all, kernel will probe it one by
728 one and will fallback to default.
730 # Alphabetically sorted list of Non standard 32 bit platforms
732 config X86_SUPPORTS_MEMORY_FAILURE
734 # MCE code calls memory_failure():
736 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
737 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
738 depends on X86_64 || !SPARSEMEM
739 select ARCH_SUPPORTS_MEMORY_FAILURE
742 bool "STA2X11 Companion Chip Support"
743 depends on X86_32_NON_STANDARD && PCI
748 This adds support for boards based on the STA2X11 IO-Hub,
749 a.k.a. "ConneXt". The chip is used in place of the standard
750 PC chipset, so all "standard" peripherals are missing. If this
751 option is selected the kernel will still be able to boot on
752 standard PC machines.
755 tristate "Eurobraille/Iris poweroff module"
758 The Iris machines from EuroBraille do not have APM or ACPI support
759 to shut themselves down properly. A special I/O sequence is
760 needed to do so, which is what this module does at
763 This is only for Iris machines from EuroBraille.
767 config SCHED_OMIT_FRAME_POINTER
769 prompt "Single-depth WCHAN output"
772 Calculate simpler /proc/<PID>/wchan values. If this option
773 is disabled then wchan values will recurse back to the
774 caller function. This provides more accurate wchan values,
775 at the expense of slightly more scheduling overhead.
777 If in doubt, say "Y".
779 menuconfig HYPERVISOR_GUEST
780 bool "Linux guest support"
782 Say Y here to enable options for running Linux under various hyper-
783 visors. This option enables basic hypervisor detection and platform
786 If you say N, all options in this submenu will be skipped and
787 disabled, and Linux guest support won't be built in.
792 bool "Enable paravirtualization code"
793 depends on HAVE_STATIC_CALL
795 This changes the kernel so it can modify itself when it is run
796 under a hypervisor, potentially improving performance significantly
797 over full virtualization. However, when run without a hypervisor
798 the kernel is theoretically slower and slightly larger.
803 config PARAVIRT_DEBUG
804 bool "paravirt-ops debugging"
805 depends on PARAVIRT && DEBUG_KERNEL
807 Enable to debug paravirt_ops internals. Specifically, BUG if
808 a paravirt_op is missing when it is called.
810 config PARAVIRT_SPINLOCKS
811 bool "Paravirtualization layer for spinlocks"
812 depends on PARAVIRT && SMP
814 Paravirtualized spinlocks allow a pvops backend to replace the
815 spinlock implementation with something virtualization-friendly
816 (for example, block the virtual CPU rather than spinning).
818 It has a minimal impact on native kernels and gives a nice performance
819 benefit on paravirtualized KVM / Xen kernels.
821 If you are unsure how to answer this question, answer Y.
823 config X86_HV_CALLBACK_VECTOR
826 source "arch/x86/xen/Kconfig"
829 bool "KVM Guest support (including kvmclock)"
831 select PARAVIRT_CLOCK
832 select ARCH_CPUIDLE_HALTPOLL
833 select X86_HV_CALLBACK_VECTOR
836 This option enables various optimizations for running under the KVM
837 hypervisor. It includes a paravirtualized clock, so that instead
838 of relying on a PIT (or probably other) emulation by the
839 underlying device model, the host provides the guest with
840 timing infrastructure such as time of day, and system time
842 config ARCH_CPUIDLE_HALTPOLL
844 prompt "Disable host haltpoll when loading haltpoll driver"
846 If virtualized under KVM, disable host haltpoll.
849 bool "Support for running PVH guests"
851 This option enables the PVH entry point for guest virtual machines
852 as specified in the x86/HVM direct boot ABI.
854 config PARAVIRT_TIME_ACCOUNTING
855 bool "Paravirtual steal time accounting"
858 Select this option to enable fine granularity task steal time
859 accounting. Time spent executing other tasks in parallel with
860 the current vCPU is discounted from the vCPU power. To account for
861 that, there can be a small performance impact.
863 If in doubt, say N here.
865 config PARAVIRT_CLOCK
868 config JAILHOUSE_GUEST
869 bool "Jailhouse non-root cell support"
870 depends on X86_64 && PCI
873 This option allows to run Linux as guest in a Jailhouse non-root
874 cell. You can leave this option disabled if you only want to start
875 Jailhouse and run Linux afterwards in the root cell.
878 bool "ACRN Guest support"
880 select X86_HV_CALLBACK_VECTOR
882 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
883 a flexible, lightweight reference open-source hypervisor, built with
884 real-time and safety-criticality in mind. It is built for embedded
885 IOT with small footprint and real-time features. More details can be
886 found in https://projectacrn.org/.
888 config INTEL_TDX_GUEST
889 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
890 depends on X86_64 && CPU_SUP_INTEL
891 depends on X86_X2APIC
893 select ARCH_HAS_CC_PLATFORM
894 select X86_MEM_ENCRYPT
896 select UNACCEPTED_MEMORY
898 Support running as a guest under Intel TDX. Without this support,
899 the guest kernel can not boot or run under TDX.
900 TDX includes memory encryption and integrity capabilities
901 which protect the confidentiality and integrity of guest
902 memory contents and CPU state. TDX guests are protected from
903 some attacks from the VMM.
905 endif # HYPERVISOR_GUEST
907 source "arch/x86/Kconfig.cpu"
911 prompt "HPET Timer Support" if X86_32
913 Use the IA-PC HPET (High Precision Event Timer) to manage
914 time in preference to the PIT and RTC, if a HPET is
916 HPET is the next generation timer replacing legacy 8254s.
917 The HPET provides a stable time base on SMP
918 systems, unlike the TSC, but it is more expensive to access,
919 as it is off-chip. The interface used is documented
920 in the HPET spec, revision 1.
922 You can safely choose Y here. However, HPET will only be
923 activated if the platform and the BIOS support this feature.
924 Otherwise the 8254 will be used for timing services.
926 Choose N to continue using the legacy 8254 timer.
928 config HPET_EMULATE_RTC
930 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
932 # Mark as expert because too many people got it wrong.
933 # The code disables itself when not needed.
936 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
937 bool "Enable DMI scanning" if EXPERT
939 Enabled scanning of DMI to identify machine quirks. Say Y
940 here unless you have verified that your setup is not
941 affected by entries in the DMI blacklist. Required by PNP
945 bool "Old AMD GART IOMMU support"
949 depends on X86_64 && PCI && AMD_NB
951 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
952 GART based hardware IOMMUs.
954 The GART supports full DMA access for devices with 32-bit access
955 limitations, on systems with more than 3 GB. This is usually needed
956 for USB, sound, many IDE/SATA chipsets and some other devices.
958 Newer systems typically have a modern AMD IOMMU, supported via
959 the CONFIG_AMD_IOMMU=y config option.
961 In normal configurations this driver is only active when needed:
962 there's more than 3 GB of memory and the system contains a
963 32-bit limited device.
967 config BOOT_VESA_SUPPORT
970 If true, at least one selected framebuffer driver can take advantage
971 of VESA video modes set at an early boot stage via the vga= parameter.
974 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
975 depends on X86_64 && SMP && DEBUG_KERNEL
976 select CPUMASK_OFFSTACK
978 Enable maximum number of CPUS and NUMA Nodes for this architecture.
982 # The maximum number of CPUs supported:
984 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
985 # and which can be configured interactively in the
986 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
988 # The ranges are different on 32-bit and 64-bit kernels, depending on
989 # hardware capabilities and scalability features of the kernel.
991 # ( If MAXSMP is enabled we just use the highest possible value and disable
992 # interactive configuration. )
995 config NR_CPUS_RANGE_BEGIN
997 default NR_CPUS_RANGE_END if MAXSMP
1001 config NR_CPUS_RANGE_END
1004 default 64 if SMP && X86_BIGSMP
1005 default 8 if SMP && !X86_BIGSMP
1008 config NR_CPUS_RANGE_END
1011 default 8192 if SMP && CPUMASK_OFFSTACK
1012 default 512 if SMP && !CPUMASK_OFFSTACK
1015 config NR_CPUS_DEFAULT
1018 default 32 if X86_BIGSMP
1022 config NR_CPUS_DEFAULT
1025 default 8192 if MAXSMP
1030 int "Maximum number of CPUs" if SMP && !MAXSMP
1031 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1032 default NR_CPUS_DEFAULT
1034 This allows you to specify the maximum number of CPUs which this
1035 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1036 supported value is 8192, otherwise the maximum value is 512. The
1037 minimum value which makes sense is 2.
1039 This is purely to save memory: each supported CPU adds about 8KB
1040 to the kernel image.
1042 config SCHED_CLUSTER
1043 bool "Cluster scheduler support"
1047 Cluster scheduler support improves the CPU scheduler's decision
1048 making when dealing with machines that have clusters of CPUs.
1049 Cluster usually means a couple of CPUs which are placed closely
1050 by sharing mid-level caches, last-level cache tags or internal
1058 prompt "Multi-core scheduler support"
1061 Multi-core scheduler support improves the CPU scheduler's decision
1062 making when dealing with multi-core CPU chips at a cost of slightly
1063 increased overhead in some places. If unsure say N here.
1065 config SCHED_MC_PRIO
1066 bool "CPU core priorities scheduler support"
1067 depends on SCHED_MC && CPU_SUP_INTEL
1068 select X86_INTEL_PSTATE
1072 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1073 core ordering determined at manufacturing time, which allows
1074 certain cores to reach higher turbo frequencies (when running
1075 single threaded workloads) than others.
1077 Enabling this kernel feature teaches the scheduler about
1078 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1079 scheduler's CPU selection logic accordingly, so that higher
1080 overall system performance can be achieved.
1082 This feature will have no effect on CPUs without this feature.
1084 If unsure say Y here.
1088 depends on !SMP && X86_LOCAL_APIC
1091 bool "Local APIC support on uniprocessors" if !PCI_MSI
1093 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1095 A local APIC (Advanced Programmable Interrupt Controller) is an
1096 integrated interrupt controller in the CPU. If you have a single-CPU
1097 system which has a processor with a local APIC, you can say Y here to
1098 enable and use it. If you say Y here even though your machine doesn't
1099 have a local APIC, then the kernel will still run with no slowdown at
1100 all. The local APIC supports CPU-generated self-interrupts (timer,
1101 performance counters), and the NMI watchdog which detects hard
1104 config X86_UP_IOAPIC
1105 bool "IO-APIC support on uniprocessors"
1106 depends on X86_UP_APIC
1108 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1109 SMP-capable replacement for PC-style interrupt controllers. Most
1110 SMP systems and many recent uniprocessor systems have one.
1112 If you have a single-CPU system with an IO-APIC, you can say Y here
1113 to use it. If you say Y here even though your machine doesn't have
1114 an IO-APIC, then the kernel will still run with no slowdown at all.
1116 config X86_LOCAL_APIC
1118 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1119 select IRQ_DOMAIN_HIERARCHY
1123 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1125 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1126 bool "Reroute for broken boot IRQs"
1127 depends on X86_IO_APIC
1129 This option enables a workaround that fixes a source of
1130 spurious interrupts. This is recommended when threaded
1131 interrupt handling is used on systems where the generation of
1132 superfluous "boot interrupts" cannot be disabled.
1134 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1135 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1136 kernel does during interrupt handling). On chipsets where this
1137 boot IRQ generation cannot be disabled, this workaround keeps
1138 the original IRQ line masked so that only the equivalent "boot
1139 IRQ" is delivered to the CPUs. The workaround also tells the
1140 kernel to set up the IRQ handler on the boot IRQ line. In this
1141 way only one interrupt is delivered to the kernel. Otherwise
1142 the spurious second interrupt may cause the kernel to bring
1143 down (vital) interrupt lines.
1145 Only affects "broken" chipsets. Interrupt sharing may be
1146 increased on these systems.
1149 bool "Machine Check / overheating reporting"
1150 select GENERIC_ALLOCATOR
1153 Machine Check support allows the processor to notify the
1154 kernel if it detects a problem (e.g. overheating, data corruption).
1155 The action the kernel takes depends on the severity of the problem,
1156 ranging from warning messages to halting the machine.
1158 config X86_MCELOG_LEGACY
1159 bool "Support for deprecated /dev/mcelog character device"
1162 Enable support for /dev/mcelog which is needed by the old mcelog
1163 userspace logging daemon. Consider switching to the new generation
1166 config X86_MCE_INTEL
1168 prompt "Intel MCE features"
1169 depends on X86_MCE && X86_LOCAL_APIC
1171 Additional support for intel specific MCE features such as
1172 the thermal monitor.
1176 prompt "AMD MCE features"
1177 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1179 Additional support for AMD specific MCE features such as
1180 the DRAM Error Threshold.
1182 config X86_ANCIENT_MCE
1183 bool "Support for old Pentium 5 / WinChip machine checks"
1184 depends on X86_32 && X86_MCE
1186 Include support for machine check handling on old Pentium 5 or WinChip
1187 systems. These typically need to be enabled explicitly on the command
1190 config X86_MCE_THRESHOLD
1191 depends on X86_MCE_AMD || X86_MCE_INTEL
1194 config X86_MCE_INJECT
1195 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1196 tristate "Machine check injector support"
1198 Provide support for injecting machine checks for testing purposes.
1199 If you don't know what a machine check is and you don't do kernel
1200 QA it is safe to say n.
1202 source "arch/x86/events/Kconfig"
1204 config X86_LEGACY_VM86
1205 bool "Legacy VM86 support"
1208 This option allows user programs to put the CPU into V8086
1209 mode, which is an 80286-era approximation of 16-bit real mode.
1211 Some very old versions of X and/or vbetool require this option
1212 for user mode setting. Similarly, DOSEMU will use it if
1213 available to accelerate real mode DOS programs. However, any
1214 recent version of DOSEMU, X, or vbetool should be fully
1215 functional even without kernel VM86 support, as they will all
1216 fall back to software emulation. Nevertheless, if you are using
1217 a 16-bit DOS program where 16-bit performance matters, vm86
1218 mode might be faster than emulation and you might want to
1221 Note that any app that works on a 64-bit kernel is unlikely to
1222 need this option, as 64-bit kernels don't, and can't, support
1223 V8086 mode. This option is also unrelated to 16-bit protected
1224 mode and is not needed to run most 16-bit programs under Wine.
1226 Enabling this option increases the complexity of the kernel
1227 and slows down exception handling a tiny bit.
1229 If unsure, say N here.
1233 default X86_LEGACY_VM86
1236 bool "Enable support for 16-bit segments" if EXPERT
1238 depends on MODIFY_LDT_SYSCALL
1240 This option is required by programs like Wine to run 16-bit
1241 protected mode legacy code on x86 processors. Disabling
1242 this option saves about 300 bytes on i386, or around 6K text
1243 plus 16K runtime memory on x86-64,
1247 depends on X86_16BIT && X86_32
1251 depends on X86_16BIT && X86_64
1253 config X86_VSYSCALL_EMULATION
1254 bool "Enable vsyscall emulation" if EXPERT
1258 This enables emulation of the legacy vsyscall page. Disabling
1259 it is roughly equivalent to booting with vsyscall=none, except
1260 that it will also disable the helpful warning if a program
1261 tries to use a vsyscall. With this option set to N, offending
1262 programs will just segfault, citing addresses of the form
1265 This option is required by many programs built before 2013, and
1266 care should be used even with newer programs if set to N.
1268 Disabling this option saves about 7K of kernel size and
1269 possibly 4K of additional runtime pagetable memory.
1271 config X86_IOPL_IOPERM
1272 bool "IOPERM and IOPL Emulation"
1275 This enables the ioperm() and iopl() syscalls which are necessary
1276 for legacy applications.
1278 Legacy IOPL support is an overbroad mechanism which allows user
1279 space aside of accessing all 65536 I/O ports also to disable
1280 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1281 capabilities and permission from potentially active security
1284 The emulation restricts the functionality of the syscall to
1285 only allowing the full range I/O port access, but prevents the
1286 ability to disable interrupts from user space which would be
1287 granted if the hardware IOPL mechanism would be used.
1290 tristate "Toshiba Laptop support"
1293 This adds a driver to safely access the System Management Mode of
1294 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1295 not work on models with a Phoenix BIOS. The System Management Mode
1296 is used to set the BIOS and power saving options on Toshiba portables.
1298 For information on utilities to make use of this driver see the
1299 Toshiba Linux utilities web site at:
1300 <http://www.buzzard.org.uk/toshiba/>.
1302 Say Y if you intend to run this kernel on a Toshiba portable.
1305 config X86_REBOOTFIXUPS
1306 bool "Enable X86 board specific fixups for reboot"
1309 This enables chipset and/or board specific fixups to be done
1310 in order to get reboot to work correctly. This is only needed on
1311 some combinations of hardware and BIOS. The symptom, for which
1312 this config is intended, is when reboot ends with a stalled/hung
1315 Currently, the only fixup is for the Geode machines using
1316 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1318 Say Y if you want to enable the fixup. Currently, it's safe to
1319 enable this option even if you don't need it.
1324 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1326 config MICROCODE_INITRD32
1328 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1330 config MICROCODE_LATE_LOADING
1331 bool "Late microcode loading (DANGEROUS)"
1333 depends on MICROCODE && SMP
1335 Loading microcode late, when the system is up and executing instructions
1336 is a tricky business and should be avoided if possible. Just the sequence
1337 of synchronizing all cores and SMT threads is one fragile dance which does
1338 not guarantee that cores might not softlock after the loading. Therefore,
1339 use this at your own risk. Late loading taints the kernel unless the
1340 microcode header indicates that it is safe for late loading via the
1341 minimal revision check. This minimal revision check can be enforced on
1342 the kernel command line with "microcode.minrev=Y".
1344 config MICROCODE_LATE_FORCE_MINREV
1345 bool "Enforce late microcode loading minimal revision check"
1347 depends on MICROCODE_LATE_LOADING
1349 To prevent that users load microcode late which modifies already
1350 in use features, newer microcode patches have a minimum revision field
1351 in the microcode header, which tells the kernel which minimum
1352 revision must be active in the CPU to safely load that new microcode
1353 late into the running system. If disabled the check will not
1354 be enforced but the kernel will be tainted when the minimal
1355 revision check fails.
1357 This minimal revision check can also be controlled via the
1358 "microcode.minrev" parameter on the kernel command line.
1363 tristate "/dev/cpu/*/msr - Model-specific register support"
1365 This device gives privileged processes access to the x86
1366 Model-Specific Registers (MSRs). It is a character device with
1367 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1368 MSR accesses are directed to a specific CPU on multi-processor
1372 tristate "/dev/cpu/*/cpuid - CPU information support"
1374 This device gives processes access to the x86 CPUID instruction to
1375 be executed on a specific processor. It is a character device
1376 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1380 prompt "High Memory Support"
1387 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1388 However, the address space of 32-bit x86 processors is only 4
1389 Gigabytes large. That means that, if you have a large amount of
1390 physical memory, not all of it can be "permanently mapped" by the
1391 kernel. The physical memory that's not permanently mapped is called
1394 If you are compiling a kernel which will never run on a machine with
1395 more than 1 Gigabyte total physical RAM, answer "off" here (default
1396 choice and suitable for most users). This will result in a "3GB/1GB"
1397 split: 3GB are mapped so that each process sees a 3GB virtual memory
1398 space and the remaining part of the 4GB virtual memory space is used
1399 by the kernel to permanently map as much physical memory as
1402 If the machine has between 1 and 4 Gigabytes physical RAM, then
1405 If more than 4 Gigabytes is used then answer "64GB" here. This
1406 selection turns Intel PAE (Physical Address Extension) mode on.
1407 PAE implements 3-level paging on IA32 processors. PAE is fully
1408 supported by Linux, PAE mode is implemented on all recent Intel
1409 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1410 then the kernel will not boot on CPUs that don't support PAE!
1412 The actual amount of total physical memory will either be
1413 auto detected or can be forced by using a kernel command line option
1414 such as "mem=256M". (Try "man bootparam" or see the documentation of
1415 your boot loader (lilo or loadlin) about how to pass options to the
1416 kernel at boot time.)
1418 If unsure, say "off".
1423 Select this if you have a 32-bit processor and between 1 and 4
1424 gigabytes of physical RAM.
1428 depends on X86_HAVE_PAE
1431 Select this if you have a 32-bit processor and more than 4
1432 gigabytes of physical RAM.
1437 prompt "Memory split" if EXPERT
1441 Select the desired split between kernel and user memory.
1443 If the address range available to the kernel is less than the
1444 physical memory installed, the remaining memory will be available
1445 as "high memory". Accessing high memory is a little more costly
1446 than low memory, as it needs to be mapped into the kernel first.
1447 Note that increasing the kernel address space limits the range
1448 available to user programs, making the address space there
1449 tighter. Selecting anything other than the default 3G/1G split
1450 will also likely make your kernel incompatible with binary-only
1453 If you are not absolutely sure what you are doing, leave this
1457 bool "3G/1G user/kernel split"
1458 config VMSPLIT_3G_OPT
1460 bool "3G/1G user/kernel split (for full 1G low memory)"
1462 bool "2G/2G user/kernel split"
1463 config VMSPLIT_2G_OPT
1465 bool "2G/2G user/kernel split (for full 2G low memory)"
1467 bool "1G/3G user/kernel split"
1472 default 0xB0000000 if VMSPLIT_3G_OPT
1473 default 0x80000000 if VMSPLIT_2G
1474 default 0x78000000 if VMSPLIT_2G_OPT
1475 default 0x40000000 if VMSPLIT_1G
1481 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1484 bool "PAE (Physical Address Extension) Support"
1485 depends on X86_32 && X86_HAVE_PAE
1486 select PHYS_ADDR_T_64BIT
1489 PAE is required for NX support, and furthermore enables
1490 larger swapspace support for non-overcommit purposes. It
1491 has the cost of more pagetable lookup overhead, and also
1492 consumes more pagetable space per process.
1495 bool "Enable 5-level page tables support"
1497 select DYNAMIC_MEMORY_LAYOUT
1498 select SPARSEMEM_VMEMMAP
1501 5-level paging enables access to larger address space:
1502 up to 128 PiB of virtual address space and 4 PiB of
1503 physical address space.
1505 It will be supported by future Intel CPUs.
1507 A kernel with the option enabled can be booted on machines that
1508 support 4- or 5-level paging.
1510 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1515 config X86_DIRECT_GBPAGES
1519 Certain kernel features effectively disable kernel
1520 linear 1 GB mappings (even if the CPU otherwise
1521 supports them), so don't confuse the user by printing
1522 that we have them enabled.
1524 config X86_CPA_STATISTICS
1525 bool "Enable statistic for Change Page Attribute"
1528 Expose statistics about the Change Page Attribute mechanism, which
1529 helps to determine the effectiveness of preserving large and huge
1530 page mappings when mapping protections are changed.
1532 config X86_MEM_ENCRYPT
1533 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1534 select DYNAMIC_PHYSICAL_MASK
1537 config AMD_MEM_ENCRYPT
1538 bool "AMD Secure Memory Encryption (SME) support"
1539 depends on X86_64 && CPU_SUP_AMD
1541 select DMA_COHERENT_POOL
1542 select ARCH_USE_MEMREMAP_PROT
1543 select INSTRUCTION_DECODER
1544 select ARCH_HAS_CC_PLATFORM
1545 select X86_MEM_ENCRYPT
1546 select UNACCEPTED_MEMORY
1548 Say yes to enable support for the encryption of system memory.
1549 This requires an AMD processor that supports Secure Memory
1552 # Common NUMA Features
1554 bool "NUMA Memory Allocation and Scheduler Support"
1556 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1557 default y if X86_BIGSMP
1558 select USE_PERCPU_NUMA_NODE_ID
1559 select OF_NUMA if OF
1561 Enable NUMA (Non-Uniform Memory Access) support.
1563 The kernel will try to allocate memory used by a CPU on the
1564 local memory controller of the CPU and add some more
1565 NUMA awareness to the kernel.
1567 For 64-bit this is recommended if the system is Intel Core i7
1568 (or later), AMD Opteron, or EM64T NUMA.
1570 For 32-bit this is only needed if you boot a 32-bit
1571 kernel on a 64-bit NUMA platform.
1573 Otherwise, you should say N.
1577 prompt "Old style AMD Opteron NUMA detection"
1578 depends on X86_64 && NUMA && PCI
1580 Enable AMD NUMA node topology detection. You should say Y here if
1581 you have a multi processor AMD system. This uses an old method to
1582 read the NUMA configuration directly from the builtin Northbridge
1583 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1584 which also takes priority if both are compiled in.
1586 config X86_64_ACPI_NUMA
1588 prompt "ACPI NUMA detection"
1589 depends on X86_64 && NUMA && ACPI && PCI
1592 Enable ACPI SRAT based node topology detection.
1595 bool "NUMA emulation"
1598 Enable NUMA emulation. A flat machine will be split
1599 into virtual nodes when booted with "numa=fake=N", where N is the
1600 number of nodes. This is only useful for debugging.
1603 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1605 default "10" if MAXSMP
1606 default "6" if X86_64
1610 Specify the maximum number of NUMA Nodes available on the target
1611 system. Increases memory reserved to accommodate various tables.
1613 config ARCH_FLATMEM_ENABLE
1615 depends on X86_32 && !NUMA
1617 config ARCH_SPARSEMEM_ENABLE
1619 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1620 select SPARSEMEM_STATIC if X86_32
1621 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1623 config ARCH_SPARSEMEM_DEFAULT
1624 def_bool X86_64 || (NUMA && X86_32)
1626 config ARCH_SELECT_MEMORY_MODEL
1628 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1630 config ARCH_MEMORY_PROBE
1631 bool "Enable sysfs memory/probe interface"
1632 depends on MEMORY_HOTPLUG
1634 This option enables a sysfs memory/probe interface for testing.
1635 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1636 If you are unsure how to answer this question, answer N.
1638 config ARCH_PROC_KCORE_TEXT
1640 depends on X86_64 && PROC_KCORE
1642 config ILLEGAL_POINTER_VALUE
1645 default 0xdead000000000000 if X86_64
1647 config X86_PMEM_LEGACY_DEVICE
1650 config X86_PMEM_LEGACY
1651 tristate "Support non-standard NVDIMMs and ADR protected memory"
1652 depends on PHYS_ADDR_T_64BIT
1654 select X86_PMEM_LEGACY_DEVICE
1655 select NUMA_KEEP_MEMINFO if NUMA
1658 Treat memory marked using the non-standard e820 type of 12 as used
1659 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1660 The kernel will offer these regions to the 'pmem' driver so
1661 they can be used for persistent storage.
1666 bool "Allocate 3rd-level pagetables from highmem"
1669 The VM uses one page table entry for each page of physical memory.
1670 For systems with a lot of RAM, this can be wasteful of precious
1671 low memory. Setting this option will put user-space page table
1672 entries in high memory.
1674 config X86_CHECK_BIOS_CORRUPTION
1675 bool "Check for low memory corruption"
1677 Periodically check for memory corruption in low memory, which
1678 is suspected to be caused by BIOS. Even when enabled in the
1679 configuration, it is disabled at runtime. Enable it by
1680 setting "memory_corruption_check=1" on the kernel command
1681 line. By default it scans the low 64k of memory every 60
1682 seconds; see the memory_corruption_check_size and
1683 memory_corruption_check_period parameters in
1684 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1686 When enabled with the default parameters, this option has
1687 almost no overhead, as it reserves a relatively small amount
1688 of memory and scans it infrequently. It both detects corruption
1689 and prevents it from affecting the running system.
1691 It is, however, intended as a diagnostic tool; if repeatable
1692 BIOS-originated corruption always affects the same memory,
1693 you can use memmap= to prevent the kernel from using that
1696 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1697 bool "Set the default setting of memory_corruption_check"
1698 depends on X86_CHECK_BIOS_CORRUPTION
1701 Set whether the default state of memory_corruption_check is
1704 config MATH_EMULATION
1706 depends on MODIFY_LDT_SYSCALL
1707 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1709 Linux can emulate a math coprocessor (used for floating point
1710 operations) if you don't have one. 486DX and Pentium processors have
1711 a math coprocessor built in, 486SX and 386 do not, unless you added
1712 a 487DX or 387, respectively. (The messages during boot time can
1713 give you some hints here ["man dmesg"].) Everyone needs either a
1714 coprocessor or this emulation.
1716 If you don't have a math coprocessor, you need to say Y here; if you
1717 say Y here even though you have a coprocessor, the coprocessor will
1718 be used nevertheless. (This behavior can be changed with the kernel
1719 command line option "no387", which comes handy if your coprocessor
1720 is broken. Try "man bootparam" or see the documentation of your boot
1721 loader (lilo or loadlin) about how to pass options to the kernel at
1722 boot time.) This means that it is a good idea to say Y here if you
1723 intend to use this kernel on different machines.
1725 More information about the internals of the Linux math coprocessor
1726 emulation can be found in <file:arch/x86/math-emu/README>.
1728 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1729 kernel, it won't hurt.
1733 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1735 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1736 the Memory Type Range Registers (MTRRs) may be used to control
1737 processor access to memory ranges. This is most useful if you have
1738 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1739 allows bus write transfers to be combined into a larger transfer
1740 before bursting over the PCI/AGP bus. This can increase performance
1741 of image write operations 2.5 times or more. Saying Y here creates a
1742 /proc/mtrr file which may be used to manipulate your processor's
1743 MTRRs. Typically the X server should use this.
1745 This code has a reasonably generic interface so that similar
1746 control registers on other processors can be easily supported
1749 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1750 Registers (ARRs) which provide a similar functionality to MTRRs. For
1751 these, the ARRs are used to emulate the MTRRs.
1752 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1753 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1754 write-combining. All of these processors are supported by this code
1755 and it makes sense to say Y here if you have one of them.
1757 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1758 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1759 can lead to all sorts of problems, so it's good to say Y here.
1761 You can safely say Y even if your machine doesn't have MTRRs, you'll
1762 just add about 9 KB to your kernel.
1764 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1766 config MTRR_SANITIZER
1768 prompt "MTRR cleanup support"
1771 Convert MTRR layout from continuous to discrete, so X drivers can
1772 add writeback entries.
1774 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1775 The largest mtrr entry size for a continuous block can be set with
1780 config MTRR_SANITIZER_ENABLE_DEFAULT
1781 int "MTRR cleanup enable value (0-1)"
1784 depends on MTRR_SANITIZER
1786 Enable mtrr cleanup default value
1788 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1789 int "MTRR cleanup spare reg num (0-7)"
1792 depends on MTRR_SANITIZER
1794 mtrr cleanup spare entries default, it can be changed via
1795 mtrr_spare_reg_nr=N on the kernel command line.
1799 prompt "x86 PAT support" if EXPERT
1802 Use PAT attributes to setup page level cache control.
1804 PATs are the modern equivalents of MTRRs and are much more
1805 flexible than MTRRs.
1807 Say N here if you see bootup problems (boot crash, boot hang,
1808 spontaneous reboots) or a non-working video driver.
1812 config ARCH_USES_PG_UNCACHED
1818 prompt "User Mode Instruction Prevention" if EXPERT
1820 User Mode Instruction Prevention (UMIP) is a security feature in
1821 some x86 processors. If enabled, a general protection fault is
1822 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1823 executed in user mode. These instructions unnecessarily expose
1824 information about the hardware state.
1826 The vast majority of applications do not use these instructions.
1827 For the very few that do, software emulation is provided in
1828 specific cases in protected and virtual-8086 modes. Emulated
1832 # GCC >= 9 and binutils >= 2.29
1833 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1835 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1836 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1837 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1838 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1844 CET features configured (Shadow stack or IBT)
1846 config X86_KERNEL_IBT
1847 prompt "Indirect Branch Tracking"
1849 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1850 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1851 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1855 Build the kernel with support for Indirect Branch Tracking, a
1856 hardware support course-grain forward-edge Control Flow Integrity
1857 protection. It enforces that all indirect calls must land on
1858 an ENDBR instruction, as such, the compiler will instrument the
1859 code with them to make this happen.
1861 In addition to building the kernel with IBT, seal all functions that
1862 are not indirect call targets, avoiding them ever becoming one.
1864 This requires LTO like objtool runs and will slow down the build. It
1865 does significantly reduce the number of ENDBR instructions in the
1868 config X86_INTEL_MEMORY_PROTECTION_KEYS
1869 prompt "Memory Protection Keys"
1871 # Note: only available in 64-bit mode
1872 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1873 select ARCH_USES_HIGH_VMA_FLAGS
1874 select ARCH_HAS_PKEYS
1876 Memory Protection Keys provides a mechanism for enforcing
1877 page-based protections, but without requiring modification of the
1878 page tables when an application changes protection domains.
1880 For details, see Documentation/core-api/protection-keys.rst
1885 prompt "TSX enable mode"
1886 depends on CPU_SUP_INTEL
1887 default X86_INTEL_TSX_MODE_OFF
1889 Intel's TSX (Transactional Synchronization Extensions) feature
1890 allows to optimize locking protocols through lock elision which
1891 can lead to a noticeable performance boost.
1893 On the other hand it has been shown that TSX can be exploited
1894 to form side channel attacks (e.g. TAA) and chances are there
1895 will be more of those attacks discovered in the future.
1897 Therefore TSX is not enabled by default (aka tsx=off). An admin
1898 might override this decision by tsx=on the command line parameter.
1899 Even with TSX enabled, the kernel will attempt to enable the best
1900 possible TAA mitigation setting depending on the microcode available
1901 for the particular machine.
1903 This option allows to set the default tsx mode between tsx=on, =off
1904 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1907 Say off if not sure, auto if TSX is in use but it should be used on safe
1908 platforms or on if TSX is in use and the security aspect of tsx is not
1911 config X86_INTEL_TSX_MODE_OFF
1914 TSX is disabled if possible - equals to tsx=off command line parameter.
1916 config X86_INTEL_TSX_MODE_ON
1919 TSX is always enabled on TSX capable HW - equals the tsx=on command
1922 config X86_INTEL_TSX_MODE_AUTO
1925 TSX is enabled on TSX capable HW that is believed to be safe against
1926 side channel attacks- equals the tsx=auto command line parameter.
1930 bool "Software Guard eXtensions (SGX)"
1931 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1933 depends on CRYPTO_SHA256=y
1935 select NUMA_KEEP_MEMINFO if NUMA
1938 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1939 that can be used by applications to set aside private regions of code
1940 and data, referred to as enclaves. An enclave's private memory can
1941 only be accessed by code running within the enclave. Accesses from
1942 outside the enclave, including other enclaves, are disallowed by
1947 config X86_USER_SHADOW_STACK
1948 bool "X86 userspace shadow stack"
1951 select ARCH_USES_HIGH_VMA_FLAGS
1954 Shadow stack protection is a hardware feature that detects function
1955 return address corruption. This helps mitigate ROP attacks.
1956 Applications must be enabled to use it, and old userspace does not
1957 get protection "for free".
1959 CPUs supporting shadow stacks were first released in 2020.
1961 See Documentation/arch/x86/shstk.rst for more information.
1965 config INTEL_TDX_HOST
1966 bool "Intel Trust Domain Extensions (TDX) host support"
1967 depends on CPU_SUP_INTEL
1969 depends on KVM_INTEL
1970 depends on X86_X2APIC
1971 select ARCH_KEEP_MEMBLOCK
1972 depends on CONTIG_ALLOC
1973 depends on !KEXEC_CORE
1976 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1977 host and certain physical attacks. This option enables necessary TDX
1978 support in the host kernel to run confidential VMs.
1983 bool "EFI runtime service support"
1986 select EFI_RUNTIME_WRAPPERS
1987 select ARCH_USE_MEMREMAP_PROT
1988 select EFI_RUNTIME_MAP if KEXEC_CORE
1990 This enables the kernel to use EFI runtime services that are
1991 available (such as the EFI variable services).
1993 This option is only useful on systems that have EFI firmware.
1994 In addition, you should use the latest ELILO loader available
1995 at <http://elilo.sourceforge.net> in order to take advantage
1996 of EFI runtime services. However, even with this option, the
1997 resultant kernel should continue to boot on existing non-EFI
2001 bool "EFI stub support"
2005 This kernel feature allows a bzImage to be loaded directly
2006 by EFI firmware without the use of a bootloader.
2008 See Documentation/admin-guide/efi-stub.rst for more information.
2010 config EFI_HANDOVER_PROTOCOL
2011 bool "EFI handover protocol (DEPRECATED)"
2015 Select this in order to include support for the deprecated EFI
2016 handover protocol, which defines alternative entry points into the
2017 EFI stub. This is a practice that has no basis in the UEFI
2018 specification, and requires a priori knowledge on the part of the
2019 bootloader about Linux/x86 specific ways of passing the command line
2020 and initrd, and where in memory those assets may be loaded.
2022 If in doubt, say Y. Even though the corresponding support is not
2023 present in upstream GRUB or other bootloaders, most distros build
2024 GRUB with numerous downstream patches applied, and may rely on the
2025 handover protocol as as result.
2028 bool "EFI mixed-mode support"
2029 depends on EFI_STUB && X86_64
2031 Enabling this feature allows a 64-bit kernel to be booted
2032 on a 32-bit firmware, provided that your CPU supports 64-bit
2035 Note that it is not possible to boot a mixed-mode enabled
2036 kernel via the EFI boot stub - a bootloader that supports
2037 the EFI handover protocol must be used.
2041 config EFI_FAKE_MEMMAP
2042 bool "Enable EFI fake memory map"
2045 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2046 this parameter, you can add arbitrary attribute to specific memory
2047 range by updating original (firmware provided) EFI memmap. This is
2048 useful for debugging of EFI memmap related feature, e.g., Address
2049 Range Mirroring feature.
2051 config EFI_MAX_FAKE_MEM
2052 int "maximum allowable number of ranges in efi_fake_mem boot option"
2053 depends on EFI_FAKE_MEMMAP
2057 Maximum allowable number of ranges in efi_fake_mem boot option.
2058 Ranges can be set up to this value using comma-separated list.
2059 The default value is 8.
2061 config EFI_RUNTIME_MAP
2062 bool "Export EFI runtime maps to sysfs" if EXPERT
2065 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2066 That memory map is required by the 2nd kernel to set up EFI virtual
2067 mappings after kexec, but can also be used for debugging purposes.
2069 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2071 source "kernel/Kconfig.hz"
2073 config ARCH_SUPPORTS_KEXEC
2076 config ARCH_SUPPORTS_KEXEC_FILE
2079 config ARCH_SELECTS_KEXEC_FILE
2081 depends on KEXEC_FILE
2082 select HAVE_IMA_KEXEC if IMA
2084 config ARCH_SUPPORTS_KEXEC_PURGATORY
2087 config ARCH_SUPPORTS_KEXEC_SIG
2090 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2093 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2096 config ARCH_SUPPORTS_KEXEC_JUMP
2099 config ARCH_SUPPORTS_CRASH_DUMP
2100 def_bool X86_64 || (X86_32 && HIGHMEM)
2102 config ARCH_SUPPORTS_CRASH_HOTPLUG
2105 config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2108 config PHYSICAL_START
2109 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2112 This gives the physical address where the kernel is loaded.
2114 If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2115 will decompress itself to above physical address and run from there.
2116 Otherwise, bzImage will run from the address where it has been loaded
2117 by the boot loader. The only exception is if it is loaded below the
2118 above physical address, in which case it will relocate itself there.
2120 In normal kdump cases one does not have to set/change this option
2121 as now bzImage can be compiled as a completely relocatable image
2122 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2123 address. This option is mainly useful for the folks who don't want
2124 to use a bzImage for capturing the crash dump and want to use a
2125 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2126 to be specifically compiled to run from a specific memory area
2127 (normally a reserved region) and this option comes handy.
2129 So if you are using bzImage for capturing the crash dump,
2130 leave the value here unchanged to 0x1000000 and set
2131 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2132 for capturing the crash dump change this value to start of
2133 the reserved region. In other words, it can be set based on
2134 the "X" value as specified in the "crashkernel=YM@XM"
2135 command line boot parameter passed to the panic-ed
2136 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2137 for more details about crash dumps.
2139 Usage of bzImage for capturing the crash dump is recommended as
2140 one does not have to build two kernels. Same kernel can be used
2141 as production kernel and capture kernel. Above option should have
2142 gone away after relocatable bzImage support is introduced. But it
2143 is present because there are users out there who continue to use
2144 vmlinux for dump capture. This option should go away down the
2147 Don't change this unless you know what you are doing.
2150 bool "Build a relocatable kernel"
2153 This builds a kernel image that retains relocation information
2154 so it can be loaded someplace besides the default 1MB.
2155 The relocations tend to make the kernel binary about 10% larger,
2156 but are discarded at runtime.
2158 One use is for the kexec on panic case where the recovery kernel
2159 must live at a different physical address than the primary
2162 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2163 it has been loaded at and the compile time physical address
2164 (CONFIG_PHYSICAL_START) is used as the minimum location.
2166 config RANDOMIZE_BASE
2167 bool "Randomize the address of the kernel image (KASLR)"
2168 depends on RELOCATABLE
2171 In support of Kernel Address Space Layout Randomization (KASLR),
2172 this randomizes the physical address at which the kernel image
2173 is decompressed and the virtual address where the kernel
2174 image is mapped, as a security feature that deters exploit
2175 attempts relying on knowledge of the location of kernel
2178 On 64-bit, the kernel physical and virtual addresses are
2179 randomized separately. The physical address will be anywhere
2180 between 16MB and the top of physical memory (up to 64TB). The
2181 virtual address will be randomized from 16MB up to 1GB (9 bits
2182 of entropy). Note that this also reduces the memory space
2183 available to kernel modules from 1.5GB to 1GB.
2185 On 32-bit, the kernel physical and virtual addresses are
2186 randomized together. They will be randomized from 16MB up to
2187 512MB (8 bits of entropy).
2189 Entropy is generated using the RDRAND instruction if it is
2190 supported. If RDTSC is supported, its value is mixed into
2191 the entropy pool as well. If neither RDRAND nor RDTSC are
2192 supported, then entropy is read from the i8254 timer. The
2193 usable entropy is limited by the kernel being built using
2194 2GB addressing, and that PHYSICAL_ALIGN must be at a
2195 minimum of 2MB. As a result, only 10 bits of entropy are
2196 theoretically possible, but the implementations are further
2197 limited due to memory layouts.
2201 # Relocation on x86 needs some additional build support
2202 config X86_NEED_RELOCS
2204 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2206 config PHYSICAL_ALIGN
2207 hex "Alignment value to which kernel should be aligned"
2209 range 0x2000 0x1000000 if X86_32
2210 range 0x200000 0x1000000 if X86_64
2212 This value puts the alignment restrictions on physical address
2213 where kernel is loaded and run from. Kernel is compiled for an
2214 address which meets above alignment restriction.
2216 If bootloader loads the kernel at a non-aligned address and
2217 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2218 address aligned to above value and run from there.
2220 If bootloader loads the kernel at a non-aligned address and
2221 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2222 load address and decompress itself to the address it has been
2223 compiled for and run from there. The address for which kernel is
2224 compiled already meets above alignment restrictions. Hence the
2225 end result is that kernel runs from a physical address meeting
2226 above alignment restrictions.
2228 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2229 this value must be a multiple of 0x200000.
2231 Don't change this unless you know what you are doing.
2233 config DYNAMIC_MEMORY_LAYOUT
2236 This option makes base addresses of vmalloc and vmemmap as well as
2237 __PAGE_OFFSET movable during boot.
2239 config RANDOMIZE_MEMORY
2240 bool "Randomize the kernel memory sections"
2242 depends on RANDOMIZE_BASE
2243 select DYNAMIC_MEMORY_LAYOUT
2244 default RANDOMIZE_BASE
2246 Randomizes the base virtual address of kernel memory sections
2247 (physical memory mapping, vmalloc & vmemmap). This security feature
2248 makes exploits relying on predictable memory locations less reliable.
2250 The order of allocations remains unchanged. Entropy is generated in
2251 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2252 configuration have in average 30,000 different possible virtual
2253 addresses for each memory section.
2257 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2258 hex "Physical memory mapping padding" if EXPERT
2259 depends on RANDOMIZE_MEMORY
2260 default "0xa" if MEMORY_HOTPLUG
2262 range 0x1 0x40 if MEMORY_HOTPLUG
2265 Define the padding in terabytes added to the existing physical
2266 memory size during kernel memory randomization. It is useful
2267 for memory hotplug support but reduces the entropy available for
2268 address randomization.
2270 If unsure, leave at the default value.
2272 config ADDRESS_MASKING
2273 bool "Linear Address Masking support"
2276 Linear Address Masking (LAM) modifies the checking that is applied
2277 to 64-bit linear addresses, allowing software to use of the
2278 untranslated address bits for metadata.
2280 The capability can be used for efficient address sanitizers (ASAN)
2281 implementation and for optimizations in JITs.
2289 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2290 depends on COMPAT_32
2292 Certain buggy versions of glibc will crash if they are
2293 presented with a 32-bit vDSO that is not mapped at the address
2294 indicated in its segment table.
2296 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2297 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2298 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2299 the only released version with the bug, but OpenSUSE 9
2300 contains a buggy "glibc 2.3.2".
2302 The symptom of the bug is that everything crashes on startup, saying:
2303 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2305 Saying Y here changes the default value of the vdso32 boot
2306 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2307 This works around the glibc bug but hurts performance.
2309 If unsure, say N: if you are compiling your own kernel, you
2310 are unlikely to be using a buggy version of glibc.
2313 prompt "vsyscall table for legacy applications"
2315 default LEGACY_VSYSCALL_XONLY
2317 Legacy user code that does not know how to find the vDSO expects
2318 to be able to issue three syscalls by calling fixed addresses in
2319 kernel space. Since this location is not randomized with ASLR,
2320 it can be used to assist security vulnerability exploitation.
2322 This setting can be changed at boot time via the kernel command
2323 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2324 is deprecated and can only be enabled using the kernel command
2327 On a system with recent enough glibc (2.14 or newer) and no
2328 static binaries, you can say None without a performance penalty
2329 to improve security.
2331 If unsure, select "Emulate execution only".
2333 config LEGACY_VSYSCALL_XONLY
2334 bool "Emulate execution only"
2336 The kernel traps and emulates calls into the fixed vsyscall
2337 address mapping and does not allow reads. This
2338 configuration is recommended when userspace might use the
2339 legacy vsyscall area but support for legacy binary
2340 instrumentation of legacy code is not needed. It mitigates
2341 certain uses of the vsyscall area as an ASLR-bypassing
2344 config LEGACY_VSYSCALL_NONE
2347 There will be no vsyscall mapping at all. This will
2348 eliminate any risk of ASLR bypass due to the vsyscall
2349 fixed address mapping. Attempts to use the vsyscalls
2350 will be reported to dmesg, so that either old or
2351 malicious userspace programs can be identified.
2356 bool "Built-in kernel command line"
2358 Allow for specifying boot arguments to the kernel at
2359 build time. On some systems (e.g. embedded ones), it is
2360 necessary or convenient to provide some or all of the
2361 kernel boot arguments with the kernel itself (that is,
2362 to not rely on the boot loader to provide them.)
2364 To compile command line arguments into the kernel,
2365 set this option to 'Y', then fill in the
2366 boot arguments in CONFIG_CMDLINE.
2368 Systems with fully functional boot loaders (i.e. non-embedded)
2369 should leave this option set to 'N'.
2372 string "Built-in kernel command string"
2373 depends on CMDLINE_BOOL
2376 Enter arguments here that should be compiled into the kernel
2377 image and used at boot time. If the boot loader provides a
2378 command line at boot time, it is appended to this string to
2379 form the full kernel command line, when the system boots.
2381 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2382 change this behavior.
2384 In most cases, the command line (whether built-in or provided
2385 by the boot loader) should specify the device for the root
2388 config CMDLINE_OVERRIDE
2389 bool "Built-in command line overrides boot loader arguments"
2390 depends on CMDLINE_BOOL && CMDLINE != ""
2392 Set this option to 'Y' to have the kernel ignore the boot loader
2393 command line, and use ONLY the built-in command line.
2395 This is used to work around broken boot loaders. This should
2396 be set to 'N' under normal conditions.
2398 config MODIFY_LDT_SYSCALL
2399 bool "Enable the LDT (local descriptor table)" if EXPERT
2402 Linux can allow user programs to install a per-process x86
2403 Local Descriptor Table (LDT) using the modify_ldt(2) system
2404 call. This is required to run 16-bit or segmented code such as
2405 DOSEMU or some Wine programs. It is also used by some very old
2406 threading libraries.
2408 Enabling this feature adds a small amount of overhead to
2409 context switches and increases the low-level kernel attack
2410 surface. Disabling it removes the modify_ldt(2) system call.
2412 Saying 'N' here may make sense for embedded or server kernels.
2414 config STRICT_SIGALTSTACK_SIZE
2415 bool "Enforce strict size checking for sigaltstack"
2416 depends on DYNAMIC_SIGFRAME
2418 For historical reasons MINSIGSTKSZ is a constant which became
2419 already too small with AVX512 support. Add a mechanism to
2420 enforce strict checking of the sigaltstack size against the
2421 real size of the FPU frame. This option enables the check
2422 by default. It can also be controlled via the kernel command
2423 line option 'strict_sas_size' independent of this config
2424 switch. Enabling it might break existing applications which
2425 allocate a too small sigaltstack but 'work' because they
2426 never get a signal delivered.
2428 Say 'N' unless you want to really enforce this check.
2430 source "kernel/livepatch/Kconfig"
2434 config CC_HAS_NAMED_AS
2435 def_bool CC_IS_GCC && GCC_VERSION >= 120100
2437 config USE_X86_SEG_SUPPORT
2439 depends on CC_HAS_NAMED_AS
2441 # -fsanitize=kernel-address (KASAN) is at the moment incompatible
2442 # with named address spaces - see GCC PR sanitizer/111736.
2447 def_bool $(cc-option,-mharden-sls=all)
2449 config CC_HAS_RETURN_THUNK
2450 def_bool $(cc-option,-mfunction-return=thunk-extern)
2452 config CC_HAS_ENTRY_PADDING
2453 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2455 config FUNCTION_PADDING_CFI
2457 default 59 if FUNCTION_ALIGNMENT_64B
2458 default 27 if FUNCTION_ALIGNMENT_32B
2459 default 11 if FUNCTION_ALIGNMENT_16B
2460 default 3 if FUNCTION_ALIGNMENT_8B
2463 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2464 # except Kconfig can't do arithmetic :/
2465 config FUNCTION_PADDING_BYTES
2467 default FUNCTION_PADDING_CFI if CFI_CLANG
2468 default FUNCTION_ALIGNMENT
2472 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2473 select FUNCTION_ALIGNMENT_16B
2477 depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2480 config HAVE_CALL_THUNKS
2482 depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2488 config PREFIX_SYMBOLS
2490 depends on CALL_PADDING && !CFI_CLANG
2492 menuconfig SPECULATION_MITIGATIONS
2493 bool "Mitigations for speculative execution vulnerabilities"
2496 Say Y here to enable options which enable mitigations for
2497 speculative execution hardware vulnerabilities.
2499 If you say N, all mitigations will be disabled. You really
2500 should know what you are doing to say so.
2502 if SPECULATION_MITIGATIONS
2504 config MITIGATION_PAGE_TABLE_ISOLATION
2505 bool "Remove the kernel mapping in user mode"
2507 depends on (X86_64 || X86_PAE)
2509 This feature reduces the number of hardware side channels by
2510 ensuring that the majority of kernel addresses are not mapped
2513 See Documentation/arch/x86/pti.rst for more details.
2515 config MITIGATION_RETPOLINE
2516 bool "Avoid speculative indirect branches in kernel"
2517 select OBJTOOL if HAVE_OBJTOOL
2520 Compile kernel with the retpoline compiler options to guard against
2521 kernel-to-user data leaks by avoiding speculative indirect
2522 branches. Requires a compiler with -mindirect-branch=thunk-extern
2523 support for full protection. The kernel may run slower.
2525 config MITIGATION_RETHUNK
2526 bool "Enable return-thunks"
2527 depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2528 select OBJTOOL if HAVE_OBJTOOL
2531 Compile the kernel with the return-thunks compiler option to guard
2532 against kernel-to-user data leaks by avoiding return speculation.
2533 Requires a compiler with -mfunction-return=thunk-extern
2534 support for full protection. The kernel may run slower.
2536 config MITIGATION_UNRET_ENTRY
2537 bool "Enable UNRET on kernel entry"
2538 depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2541 Compile the kernel with support for the retbleed=unret mitigation.
2543 config MITIGATION_CALL_DEPTH_TRACKING
2544 bool "Mitigate RSB underflow with call depth tracking"
2545 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2546 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2550 Compile the kernel with call depth tracking to mitigate the Intel
2551 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2552 mitigation is off by default and needs to be enabled on the
2553 kernel command line via the retbleed=stuff option. For
2554 non-affected systems the overhead of this option is marginal as
2555 the call depth tracking is using run-time generated call thunks
2556 in a compiler generated padding area and call patching. This
2557 increases text size by ~5%. For non affected systems this space
2558 is unused. On affected SKL systems this results in a significant
2559 performance gain over the IBRS mitigation.
2561 config CALL_THUNKS_DEBUG
2562 bool "Enable call thunks and call depth tracking debugging"
2563 depends on MITIGATION_CALL_DEPTH_TRACKING
2564 select FUNCTION_ALIGNMENT_32B
2567 Enable call/ret counters for imbalance detection and build in
2568 a noisy dmesg about callthunks generation and call patching for
2569 trouble shooting. The debug prints need to be enabled on the
2570 kernel command line with 'debug-callthunks'.
2571 Only enable this when you are debugging call thunks as this
2572 creates a noticeable runtime overhead. If unsure say N.
2574 config MITIGATION_IBPB_ENTRY
2575 bool "Enable IBPB on kernel entry"
2576 depends on CPU_SUP_AMD && X86_64
2579 Compile the kernel with support for the retbleed=ibpb mitigation.
2581 config MITIGATION_IBRS_ENTRY
2582 bool "Enable IBRS on kernel entry"
2583 depends on CPU_SUP_INTEL && X86_64
2586 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2587 This mitigates both spectre_v2 and retbleed at great cost to
2590 config MITIGATION_SRSO
2591 bool "Mitigate speculative RAS overflow on AMD"
2592 depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2595 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2597 config MITIGATION_SLS
2598 bool "Mitigate Straight-Line-Speculation"
2599 depends on CC_HAS_SLS && X86_64
2600 select OBJTOOL if HAVE_OBJTOOL
2603 Compile the kernel with straight-line-speculation options to guard
2604 against straight line speculation. The kernel image might be slightly
2607 config MITIGATION_GDS_FORCE
2608 bool "Force GDS Mitigation"
2609 depends on CPU_SUP_INTEL
2612 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2613 unprivileged speculative access to data which was previously stored in
2616 This option is equivalent to setting gather_data_sampling=force on the
2617 command line. The microcode mitigation is used if present, otherwise
2618 AVX is disabled as a mitigation. On affected systems that are missing
2619 the microcode any userspace code that unconditionally uses AVX will
2620 break with this option set.
2622 Setting this option on systems not vulnerable to GDS has no effect.
2628 config ARCH_HAS_ADD_PAGES
2630 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2632 menu "Power management and ACPI options"
2634 config ARCH_HIBERNATION_HEADER
2636 depends on HIBERNATION
2638 source "kernel/power/Kconfig"
2640 source "drivers/acpi/Kconfig"
2647 tristate "APM (Advanced Power Management) BIOS support"
2648 depends on X86_32 && PM_SLEEP
2650 APM is a BIOS specification for saving power using several different
2651 techniques. This is mostly useful for battery powered laptops with
2652 APM compliant BIOSes. If you say Y here, the system time will be
2653 reset after a RESUME operation, the /proc/apm device will provide
2654 battery status information, and user-space programs will receive
2655 notification of APM "events" (e.g. battery status change).
2657 If you select "Y" here, you can disable actual use of the APM
2658 BIOS by passing the "apm=off" option to the kernel at boot time.
2660 Note that the APM support is almost completely disabled for
2661 machines with more than one CPU.
2663 In order to use APM, you will need supporting software. For location
2664 and more information, read <file:Documentation/power/apm-acpi.rst>
2665 and the Battery Powered Linux mini-HOWTO, available from
2666 <http://www.tldp.org/docs.html#howto>.
2668 This driver does not spin down disk drives (see the hdparm(8)
2669 manpage ("man 8 hdparm") for that), and it doesn't turn off
2670 VESA-compliant "green" monitors.
2672 This driver does not support the TI 4000M TravelMate and the ACER
2673 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2674 desktop machines also don't have compliant BIOSes, and this driver
2675 may cause those machines to panic during the boot phase.
2677 Generally, if you don't have a battery in your machine, there isn't
2678 much point in using this driver and you should say N. If you get
2679 random kernel OOPSes or reboots that don't seem to be related to
2680 anything, try disabling/enabling this option (or disabling/enabling
2683 Some other things you should try when experiencing seemingly random,
2686 1) make sure that you have enough swap space and that it is
2688 2) pass the "idle=poll" option to the kernel
2689 3) switch on floating point emulation in the kernel and pass
2690 the "no387" option to the kernel
2691 4) pass the "floppy=nodma" option to the kernel
2692 5) pass the "mem=4M" option to the kernel (thereby disabling
2693 all but the first 4 MB of RAM)
2694 6) make sure that the CPU is not over clocked.
2695 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2696 8) disable the cache from your BIOS settings
2697 9) install a fan for the video card or exchange video RAM
2698 10) install a better fan for the CPU
2699 11) exchange RAM chips
2700 12) exchange the motherboard.
2702 To compile this driver as a module, choose M here: the
2703 module will be called apm.
2707 config APM_IGNORE_USER_SUSPEND
2708 bool "Ignore USER SUSPEND"
2710 This option will ignore USER SUSPEND requests. On machines with a
2711 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2712 series notebooks, it is necessary to say Y because of a BIOS bug.
2714 config APM_DO_ENABLE
2715 bool "Enable PM at boot time"
2717 Enable APM features at boot time. From page 36 of the APM BIOS
2718 specification: "When disabled, the APM BIOS does not automatically
2719 power manage devices, enter the Standby State, enter the Suspend
2720 State, or take power saving steps in response to CPU Idle calls."
2721 This driver will make CPU Idle calls when Linux is idle (unless this
2722 feature is turned off -- see "Do CPU IDLE calls", below). This
2723 should always save battery power, but more complicated APM features
2724 will be dependent on your BIOS implementation. You may need to turn
2725 this option off if your computer hangs at boot time when using APM
2726 support, or if it beeps continuously instead of suspending. Turn
2727 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2728 T400CDT. This is off by default since most machines do fine without
2733 bool "Make CPU Idle calls when idle"
2735 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2736 On some machines, this can activate improved power savings, such as
2737 a slowed CPU clock rate, when the machine is idle. These idle calls
2738 are made after the idle loop has run for some length of time (e.g.,
2739 333 mS). On some machines, this will cause a hang at boot time or
2740 whenever the CPU becomes idle. (On machines with more than one CPU,
2741 this option does nothing.)
2743 config APM_DISPLAY_BLANK
2744 bool "Enable console blanking using APM"
2746 Enable console blanking using the APM. Some laptops can use this to
2747 turn off the LCD backlight when the screen blanker of the Linux
2748 virtual console blanks the screen. Note that this is only used by
2749 the virtual console screen blanker, and won't turn off the backlight
2750 when using the X Window system. This also doesn't have anything to
2751 do with your VESA-compliant power-saving monitor. Further, this
2752 option doesn't work for all laptops -- it might not turn off your
2753 backlight at all, or it might print a lot of errors to the console,
2754 especially if you are using gpm.
2756 config APM_ALLOW_INTS
2757 bool "Allow interrupts during APM BIOS calls"
2759 Normally we disable external interrupts while we are making calls to
2760 the APM BIOS as a measure to lessen the effects of a badly behaving
2761 BIOS implementation. The BIOS should reenable interrupts if it
2762 needs to. Unfortunately, some BIOSes do not -- especially those in
2763 many of the newer IBM Thinkpads. If you experience hangs when you
2764 suspend, try setting this to Y. Otherwise, say N.
2768 source "drivers/cpufreq/Kconfig"
2770 source "drivers/cpuidle/Kconfig"
2772 source "drivers/idle/Kconfig"
2776 menu "Bus options (PCI etc.)"
2779 prompt "PCI access mode"
2780 depends on X86_32 && PCI
2783 On PCI systems, the BIOS can be used to detect the PCI devices and
2784 determine their configuration. However, some old PCI motherboards
2785 have BIOS bugs and may crash if this is done. Also, some embedded
2786 PCI-based systems don't have any BIOS at all. Linux can also try to
2787 detect the PCI hardware directly without using the BIOS.
2789 With this option, you can specify how Linux should detect the
2790 PCI devices. If you choose "BIOS", the BIOS will be used,
2791 if you choose "Direct", the BIOS won't be used, and if you
2792 choose "MMConfig", then PCI Express MMCONFIG will be used.
2793 If you choose "Any", the kernel will try MMCONFIG, then the
2794 direct access method and falls back to the BIOS if that doesn't
2795 work. If unsure, go with the default, which is "Any".
2800 config PCI_GOMMCONFIG
2817 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2819 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2822 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2825 bool "Support mmconfig PCI config space access" if X86_64
2827 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2828 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2832 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2836 depends on PCI && XEN
2838 config MMCONF_FAM10H
2840 depends on X86_64 && PCI_MMCONFIG && ACPI
2842 config PCI_CNB20LE_QUIRK
2843 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2846 Read the PCI windows out of the CNB20LE host bridge. This allows
2847 PCI hotplug to work on systems with the CNB20LE chipset which do
2850 There's no public spec for this chipset, and this functionality
2851 is known to be incomplete.
2853 You should say N unless you know you need this.
2856 bool "ISA bus support on modern systems" if EXPERT
2858 Expose ISA bus device drivers and options available for selection and
2859 configuration. Enable this option if your target machine has an ISA
2860 bus. ISA is an older system, displaced by PCI and newer bus
2861 architectures -- if your target machine is modern, it probably does
2862 not have an ISA bus.
2866 # x86_64 have no ISA slots, but can have ISA-style DMA.
2868 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2871 Enables ISA-style DMA support for devices requiring such controllers.
2879 Find out whether you have ISA slots on your motherboard. ISA is the
2880 name of a bus system, i.e. the way the CPU talks to the other stuff
2881 inside your box. Other bus systems are PCI, EISA, MicroChannel
2882 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2883 newer boards don't support it. If you have ISA, say Y, otherwise N.
2886 tristate "NatSemi SCx200 support"
2888 This provides basic support for National Semiconductor's
2889 (now AMD's) Geode processors. The driver probes for the
2890 PCI-IDs of several on-chip devices, so its a good dependency
2891 for other scx200_* drivers.
2893 If compiled as a module, the driver is named scx200.
2895 config SCx200HR_TIMER
2896 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2900 This driver provides a clocksource built upon the on-chip
2901 27MHz high-resolution timer. Its also a workaround for
2902 NSC Geode SC-1100's buggy TSC, which loses time when the
2903 processor goes idle (as is done by the scheduler). The
2904 other workaround is idle=poll boot option.
2907 bool "One Laptop Per Child support"
2915 Add support for detecting the unique features of the OLPC
2919 bool "OLPC XO-1 Power Management"
2920 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2922 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2925 bool "OLPC XO-1 Real Time Clock"
2926 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2928 Add support for the XO-1 real time clock, which can be used as a
2929 programmable wakeup source.
2932 bool "OLPC XO-1 SCI extras"
2933 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2937 Add support for SCI-based features of the OLPC XO-1 laptop:
2938 - EC-driven system wakeups
2942 - AC adapter status updates
2943 - Battery status updates
2945 config OLPC_XO15_SCI
2946 bool "OLPC XO-1.5 SCI extras"
2947 depends on OLPC && ACPI
2950 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2951 - EC-driven system wakeups
2952 - AC adapter status updates
2953 - Battery status updates
2956 bool "PCEngines ALIX System Support (LED setup)"
2959 This option enables system support for the PCEngines ALIX.
2960 At present this just sets up LEDs for GPIO control on
2961 ALIX2/3/6 boards. However, other system specific setup should
2964 Note: You must still enable the drivers for GPIO and LED support
2965 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2967 Note: You have to set alix.force=1 for boards with Award BIOS.
2970 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2973 This option enables system support for the Soekris Engineering net5501.
2976 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2980 This option enables system support for the Traverse Technologies GEOS.
2983 bool "Technologic Systems TS-5500 platform support"
2985 select CHECK_SIGNATURE
2989 This option enables system support for the Technologic Systems TS-5500.
2995 depends on CPU_SUP_AMD && PCI
2999 menu "Binary Emulations"
3001 config IA32_EMULATION
3002 bool "IA32 Emulation"
3004 select ARCH_WANT_OLD_COMPAT_IPC
3006 select COMPAT_OLD_SIGACTION
3008 Include code to run legacy 32-bit programs under a
3009 64-bit kernel. You should likely turn this on, unless you're
3010 100% sure that you don't have any 32-bit programs left.
3012 config IA32_EMULATION_DEFAULT_DISABLED
3013 bool "IA32 emulation disabled by default"
3015 depends on IA32_EMULATION
3017 Make IA32 emulation disabled by default. This prevents loading 32-bit
3018 processes and access to 32-bit syscalls. If unsure, leave it to its
3022 bool "x32 ABI for 64-bit mode"
3024 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3025 # compressed debug sections to x86_x32 properly:
3026 # https://github.com/ClangBuiltLinux/linux/issues/514
3027 # https://github.com/ClangBuiltLinux/linux/issues/1141
3028 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3030 Include code to run binaries for the x32 native 32-bit ABI
3031 for 64-bit processors. An x32 process gets access to the
3032 full 64-bit register file and wide data path while leaving
3033 pointers at 32 bits for smaller memory footprint.
3037 depends on IA32_EMULATION || X86_32
3039 select OLD_SIGSUSPEND3
3043 depends on IA32_EMULATION || X86_X32_ABI
3045 config COMPAT_FOR_U64_ALIGNMENT
3051 config HAVE_ATOMIC_IOMAP
3055 source "arch/x86/kvm/Kconfig"
3057 source "arch/x86/Kconfig.assembler"