1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_SUPPORTS_PER_VMA_LOCK
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
63 select ARCH_32BIT_OFF_T if X86_32
64 select ARCH_CLOCKSOURCE_INIT
65 select ARCH_CONFIGURES_CPU_MITIGATIONS
66 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
67 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
68 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
69 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
70 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
71 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
72 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
73 select ARCH_HAS_CACHE_LINE_SIZE
74 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
75 select ARCH_HAS_CPU_FINALIZE_INIT
76 select ARCH_HAS_CPU_PASID if IOMMU_SVA
77 select ARCH_HAS_CURRENT_STACK_POINTER
78 select ARCH_HAS_DEBUG_VIRTUAL
79 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
80 select ARCH_HAS_DEVMEM_IS_ALLOWED
81 select ARCH_HAS_EARLY_DEBUG if KGDB
82 select ARCH_HAS_ELF_RANDOMIZE
83 select ARCH_HAS_FAST_MULTIPLIER
84 select ARCH_HAS_FORTIFY_SOURCE
85 select ARCH_HAS_GCOV_PROFILE_ALL
86 select ARCH_HAS_KCOV if X86_64
87 select ARCH_HAS_MEM_ENCRYPT
88 select ARCH_HAS_MEMBARRIER_SYNC_CORE
89 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
90 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
91 select ARCH_HAS_PMEM_API if X86_64
92 select ARCH_HAS_PTE_DEVMAP if X86_64
93 select ARCH_HAS_PTE_SPECIAL
94 select ARCH_HAS_HW_PTE_YOUNG
95 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
96 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
97 select ARCH_HAS_COPY_MC if X86_64
98 select ARCH_HAS_SET_MEMORY
99 select ARCH_HAS_SET_DIRECT_MAP
100 select ARCH_HAS_STRICT_KERNEL_RWX
101 select ARCH_HAS_STRICT_MODULE_RWX
102 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
103 select ARCH_HAS_SYSCALL_WRAPPER
104 select ARCH_HAS_UBSAN_SANITIZE_ALL
105 select ARCH_HAS_DEBUG_WX
106 select ARCH_HAS_ZONE_DMA_SET if EXPERT
107 select ARCH_HAVE_NMI_SAFE_CMPXCHG
108 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
109 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
110 select ARCH_MIGHT_HAVE_PC_PARPORT
111 select ARCH_MIGHT_HAVE_PC_SERIO
112 select ARCH_STACKWALK
113 select ARCH_SUPPORTS_ACPI
114 select ARCH_SUPPORTS_ATOMIC_RMW
115 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
116 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
117 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
118 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
119 select ARCH_SUPPORTS_CFI_CLANG if X86_64
120 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
121 select ARCH_SUPPORTS_LTO_CLANG
122 select ARCH_SUPPORTS_LTO_CLANG_THIN
123 select ARCH_USE_BUILTIN_BSWAP
124 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
125 select ARCH_USE_MEMTEST
126 select ARCH_USE_QUEUED_RWLOCKS
127 select ARCH_USE_QUEUED_SPINLOCKS
128 select ARCH_USE_SYM_ANNOTATIONS
129 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
130 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
131 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
132 select ARCH_WANTS_NO_INSTR
133 select ARCH_WANT_GENERAL_HUGETLB
134 select ARCH_WANT_HUGE_PMD_SHARE
135 select ARCH_WANT_LD_ORPHAN_WARN
136 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
137 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
138 select ARCH_WANTS_THP_SWAP if X86_64
139 select ARCH_HAS_PARANOID_L1D_FLUSH
140 select BUILDTIME_TABLE_SORT
142 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
143 select CLOCKSOURCE_WATCHDOG
144 # Word-size accesses may read uninitialized data past the trailing \0
145 # in strings and cause false KMSAN reports.
146 select DCACHE_WORD_ACCESS if !KMSAN
147 select DYNAMIC_SIGFRAME
148 select EDAC_ATOMIC_SCRUB
150 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
151 select GENERIC_CLOCKEVENTS_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.
502 bool "Support for big SMP systems with more than 8 CPUs"
505 This option is needed for the systems that have more than 8 CPUs.
507 config X86_EXTENDED_PLATFORM
508 bool "Support for extended (non-PC) x86 platforms"
511 If you disable this option then the kernel will only support
512 standard PC platforms. (which covers the vast majority of
515 If you enable this option then you'll be able to select support
516 for the following (non-PC) 32 bit x86 platforms:
517 Goldfish (Android emulator)
520 SGI 320/540 (Visual Workstation)
521 STA2X11-based (e.g. Northville)
522 Moorestown MID devices
524 If you have one of these systems, or if you want to build a
525 generic distribution kernel, say Y here - otherwise say N.
529 config X86_EXTENDED_PLATFORM
530 bool "Support for extended (non-PC) x86 platforms"
533 If you disable this option then the kernel will only support
534 standard PC platforms. (which covers the vast majority of
537 If you enable this option then you'll be able to select support
538 for the following (non-PC) 64 bit x86 platforms:
543 If you have one of these systems, or if you want to build a
544 generic distribution kernel, say Y here - otherwise say N.
546 # This is an alphabetically sorted list of 64 bit extended platforms
547 # Please maintain the alphabetic order if and when there are additions
549 bool "Numascale NumaChip"
551 depends on X86_EXTENDED_PLATFORM
554 depends on X86_X2APIC
555 depends on PCI_MMCONFIG
557 Adds support for Numascale NumaChip large-SMP systems. Needed to
558 enable more than ~168 cores.
559 If you don't have one of these, you should say N here.
563 select HYPERVISOR_GUEST
565 depends on X86_64 && PCI
566 depends on X86_EXTENDED_PLATFORM
569 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
570 supposed to run on these EM64T-based machines. Only choose this option
571 if you have one of these machines.
574 bool "SGI Ultraviolet"
576 depends on X86_EXTENDED_PLATFORM
579 depends on KEXEC_CORE
580 depends on X86_X2APIC
583 This option is needed in order to support SGI Ultraviolet systems.
584 If you don't have one of these, you should say N here.
586 # Following is an alphabetically sorted list of 32 bit extended platforms
587 # Please maintain the alphabetic order if and when there are additions
590 bool "Goldfish (Virtual Platform)"
591 depends on X86_EXTENDED_PLATFORM
593 Enable support for the Goldfish virtual platform used primarily
594 for Android development. Unless you are building for the Android
595 Goldfish emulator say N here.
598 bool "CE4100 TV platform"
600 depends on PCI_GODIRECT
601 depends on X86_IO_APIC
603 depends on X86_EXTENDED_PLATFORM
604 select X86_REBOOTFIXUPS
606 select OF_EARLY_FLATTREE
608 Select for the Intel CE media processor (CE4100) SOC.
609 This option compiles in support for the CE4100 SOC for settop
610 boxes and media devices.
613 bool "Intel MID platform support"
614 depends on X86_EXTENDED_PLATFORM
615 depends on X86_PLATFORM_DEVICES
617 depends on X86_64 || (PCI_GOANY && X86_32)
618 depends on X86_IO_APIC
623 Select to build a kernel capable of supporting Intel MID (Mobile
624 Internet Device) platform systems which do not have the PCI legacy
625 interfaces. If you are building for a PC class system say N here.
627 Intel MID platforms are based on an Intel processor and chipset which
628 consume less power than most of the x86 derivatives.
630 config X86_INTEL_QUARK
631 bool "Intel Quark platform support"
633 depends on X86_EXTENDED_PLATFORM
634 depends on X86_PLATFORM_DEVICES
638 depends on X86_IO_APIC
643 Select to include support for Quark X1000 SoC.
644 Say Y here if you have a Quark based system such as the Arduino
645 compatible Intel Galileo.
647 config X86_INTEL_LPSS
648 bool "Intel Low Power Subsystem Support"
649 depends on X86 && ACPI && PCI
654 Select to build support for Intel Low Power Subsystem such as
655 found on Intel Lynxpoint PCH. Selecting this option enables
656 things like clock tree (common clock framework) and pincontrol
657 which are needed by the LPSS peripheral drivers.
659 config X86_AMD_PLATFORM_DEVICE
660 bool "AMD ACPI2Platform devices support"
665 Select to interpret AMD specific ACPI device to platform device
666 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
667 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
668 implemented under PINCTRL subsystem.
671 tristate "Intel SoC IOSF Sideband support for SoC platforms"
674 This option enables sideband register access support for Intel SoC
675 platforms. On these platforms the IOSF sideband is used in lieu of
676 MSR's for some register accesses, mostly but not limited to thermal
677 and power. Drivers may query the availability of this device to
678 determine if they need the sideband in order to work on these
679 platforms. The sideband is available on the following SoC products.
680 This list is not meant to be exclusive.
685 You should say Y if you are running a kernel on one of these SoC's.
687 config IOSF_MBI_DEBUG
688 bool "Enable IOSF sideband access through debugfs"
689 depends on IOSF_MBI && DEBUG_FS
691 Select this option to expose the IOSF sideband access registers (MCR,
692 MDR, MCRX) through debugfs to write and read register information from
693 different units on the SoC. This is most useful for obtaining device
694 state information for debug and analysis. As this is a general access
695 mechanism, users of this option would have specific knowledge of the
696 device they want to access.
698 If you don't require the option or are in doubt, say N.
701 bool "RDC R-321x SoC"
703 depends on X86_EXTENDED_PLATFORM
705 select X86_REBOOTFIXUPS
707 This option is needed for RDC R-321x system-on-chip, also known
709 If you don't have one of these chips, you should say N here.
711 config X86_32_NON_STANDARD
712 bool "Support non-standard 32-bit SMP architectures"
713 depends on X86_32 && SMP
714 depends on X86_EXTENDED_PLATFORM
716 This option compiles in the bigsmp and STA2X11 default
717 subarchitectures. It is intended for a generic binary
718 kernel. If you select them all, kernel will probe it one by
719 one and will fallback to default.
721 # Alphabetically sorted list of Non standard 32 bit platforms
723 config X86_SUPPORTS_MEMORY_FAILURE
725 # MCE code calls memory_failure():
727 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
728 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
729 depends on X86_64 || !SPARSEMEM
730 select ARCH_SUPPORTS_MEMORY_FAILURE
733 bool "STA2X11 Companion Chip Support"
734 depends on X86_32_NON_STANDARD && PCI
739 This adds support for boards based on the STA2X11 IO-Hub,
740 a.k.a. "ConneXt". The chip is used in place of the standard
741 PC chipset, so all "standard" peripherals are missing. If this
742 option is selected the kernel will still be able to boot on
743 standard PC machines.
746 tristate "Eurobraille/Iris poweroff module"
749 The Iris machines from EuroBraille do not have APM or ACPI support
750 to shut themselves down properly. A special I/O sequence is
751 needed to do so, which is what this module does at
754 This is only for Iris machines from EuroBraille.
758 config SCHED_OMIT_FRAME_POINTER
760 prompt "Single-depth WCHAN output"
763 Calculate simpler /proc/<PID>/wchan values. If this option
764 is disabled then wchan values will recurse back to the
765 caller function. This provides more accurate wchan values,
766 at the expense of slightly more scheduling overhead.
768 If in doubt, say "Y".
770 menuconfig HYPERVISOR_GUEST
771 bool "Linux guest support"
773 Say Y here to enable options for running Linux under various hyper-
774 visors. This option enables basic hypervisor detection and platform
777 If you say N, all options in this submenu will be skipped and
778 disabled, and Linux guest support won't be built in.
783 bool "Enable paravirtualization code"
784 depends on HAVE_STATIC_CALL
786 This changes the kernel so it can modify itself when it is run
787 under a hypervisor, potentially improving performance significantly
788 over full virtualization. However, when run without a hypervisor
789 the kernel is theoretically slower and slightly larger.
794 config PARAVIRT_DEBUG
795 bool "paravirt-ops debugging"
796 depends on PARAVIRT && DEBUG_KERNEL
798 Enable to debug paravirt_ops internals. Specifically, BUG if
799 a paravirt_op is missing when it is called.
801 config PARAVIRT_SPINLOCKS
802 bool "Paravirtualization layer for spinlocks"
803 depends on PARAVIRT && SMP
805 Paravirtualized spinlocks allow a pvops backend to replace the
806 spinlock implementation with something virtualization-friendly
807 (for example, block the virtual CPU rather than spinning).
809 It has a minimal impact on native kernels and gives a nice performance
810 benefit on paravirtualized KVM / Xen kernels.
812 If you are unsure how to answer this question, answer Y.
814 config X86_HV_CALLBACK_VECTOR
817 source "arch/x86/xen/Kconfig"
820 bool "KVM Guest support (including kvmclock)"
822 select PARAVIRT_CLOCK
823 select ARCH_CPUIDLE_HALTPOLL
824 select X86_HV_CALLBACK_VECTOR
827 This option enables various optimizations for running under the KVM
828 hypervisor. It includes a paravirtualized clock, so that instead
829 of relying on a PIT (or probably other) emulation by the
830 underlying device model, the host provides the guest with
831 timing infrastructure such as time of day, and system time
833 config ARCH_CPUIDLE_HALTPOLL
835 prompt "Disable host haltpoll when loading haltpoll driver"
837 If virtualized under KVM, disable host haltpoll.
840 bool "Support for running PVH guests"
842 This option enables the PVH entry point for guest virtual machines
843 as specified in the x86/HVM direct boot ABI.
845 config PARAVIRT_TIME_ACCOUNTING
846 bool "Paravirtual steal time accounting"
849 Select this option to enable fine granularity task steal time
850 accounting. Time spent executing other tasks in parallel with
851 the current vCPU is discounted from the vCPU power. To account for
852 that, there can be a small performance impact.
854 If in doubt, say N here.
856 config PARAVIRT_CLOCK
859 config JAILHOUSE_GUEST
860 bool "Jailhouse non-root cell support"
861 depends on X86_64 && PCI
864 This option allows to run Linux as guest in a Jailhouse non-root
865 cell. You can leave this option disabled if you only want to start
866 Jailhouse and run Linux afterwards in the root cell.
869 bool "ACRN Guest support"
871 select X86_HV_CALLBACK_VECTOR
873 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
874 a flexible, lightweight reference open-source hypervisor, built with
875 real-time and safety-criticality in mind. It is built for embedded
876 IOT with small footprint and real-time features. More details can be
877 found in https://projectacrn.org/.
879 config INTEL_TDX_GUEST
880 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
881 depends on X86_64 && CPU_SUP_INTEL
882 depends on X86_X2APIC
884 select ARCH_HAS_CC_PLATFORM
885 select X86_MEM_ENCRYPT
887 select UNACCEPTED_MEMORY
889 Support running as a guest under Intel TDX. Without this support,
890 the guest kernel can not boot or run under TDX.
891 TDX includes memory encryption and integrity capabilities
892 which protect the confidentiality and integrity of guest
893 memory contents and CPU state. TDX guests are protected from
894 some attacks from the VMM.
896 endif # HYPERVISOR_GUEST
898 source "arch/x86/Kconfig.cpu"
902 prompt "HPET Timer Support" if X86_32
904 Use the IA-PC HPET (High Precision Event Timer) to manage
905 time in preference to the PIT and RTC, if a HPET is
907 HPET is the next generation timer replacing legacy 8254s.
908 The HPET provides a stable time base on SMP
909 systems, unlike the TSC, but it is more expensive to access,
910 as it is off-chip. The interface used is documented
911 in the HPET spec, revision 1.
913 You can safely choose Y here. However, HPET will only be
914 activated if the platform and the BIOS support this feature.
915 Otherwise the 8254 will be used for timing services.
917 Choose N to continue using the legacy 8254 timer.
919 config HPET_EMULATE_RTC
921 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
923 # Mark as expert because too many people got it wrong.
924 # The code disables itself when not needed.
927 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
928 bool "Enable DMI scanning" if EXPERT
930 Enabled scanning of DMI to identify machine quirks. Say Y
931 here unless you have verified that your setup is not
932 affected by entries in the DMI blacklist. Required by PNP
936 bool "Old AMD GART IOMMU support"
940 depends on X86_64 && PCI && AMD_NB
942 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
943 GART based hardware IOMMUs.
945 The GART supports full DMA access for devices with 32-bit access
946 limitations, on systems with more than 3 GB. This is usually needed
947 for USB, sound, many IDE/SATA chipsets and some other devices.
949 Newer systems typically have a modern AMD IOMMU, supported via
950 the CONFIG_AMD_IOMMU=y config option.
952 In normal configurations this driver is only active when needed:
953 there's more than 3 GB of memory and the system contains a
954 32-bit limited device.
958 config BOOT_VESA_SUPPORT
961 If true, at least one selected framebuffer driver can take advantage
962 of VESA video modes set at an early boot stage via the vga= parameter.
965 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
966 depends on X86_64 && SMP && DEBUG_KERNEL
967 select CPUMASK_OFFSTACK
969 Enable maximum number of CPUS and NUMA Nodes for this architecture.
973 # The maximum number of CPUs supported:
975 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
976 # and which can be configured interactively in the
977 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
979 # The ranges are different on 32-bit and 64-bit kernels, depending on
980 # hardware capabilities and scalability features of the kernel.
982 # ( If MAXSMP is enabled we just use the highest possible value and disable
983 # interactive configuration. )
986 config NR_CPUS_RANGE_BEGIN
988 default NR_CPUS_RANGE_END if MAXSMP
992 config NR_CPUS_RANGE_END
995 default 64 if SMP && X86_BIGSMP
996 default 8 if SMP && !X86_BIGSMP
999 config NR_CPUS_RANGE_END
1002 default 8192 if SMP && CPUMASK_OFFSTACK
1003 default 512 if SMP && !CPUMASK_OFFSTACK
1006 config NR_CPUS_DEFAULT
1009 default 32 if X86_BIGSMP
1013 config NR_CPUS_DEFAULT
1016 default 8192 if MAXSMP
1021 int "Maximum number of CPUs" if SMP && !MAXSMP
1022 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1023 default NR_CPUS_DEFAULT
1025 This allows you to specify the maximum number of CPUs which this
1026 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1027 supported value is 8192, otherwise the maximum value is 512. The
1028 minimum value which makes sense is 2.
1030 This is purely to save memory: each supported CPU adds about 8KB
1031 to the kernel image.
1033 config SCHED_CLUSTER
1034 bool "Cluster scheduler support"
1038 Cluster scheduler support improves the CPU scheduler's decision
1039 making when dealing with machines that have clusters of CPUs.
1040 Cluster usually means a couple of CPUs which are placed closely
1041 by sharing mid-level caches, last-level cache tags or internal
1049 prompt "Multi-core scheduler support"
1052 Multi-core scheduler support improves the CPU scheduler's decision
1053 making when dealing with multi-core CPU chips at a cost of slightly
1054 increased overhead in some places. If unsure say N here.
1056 config SCHED_MC_PRIO
1057 bool "CPU core priorities scheduler support"
1058 depends on SCHED_MC && CPU_SUP_INTEL
1059 select X86_INTEL_PSTATE
1063 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1064 core ordering determined at manufacturing time, which allows
1065 certain cores to reach higher turbo frequencies (when running
1066 single threaded workloads) than others.
1068 Enabling this kernel feature teaches the scheduler about
1069 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1070 scheduler's CPU selection logic accordingly, so that higher
1071 overall system performance can be achieved.
1073 This feature will have no effect on CPUs without this feature.
1075 If unsure say Y here.
1079 depends on !SMP && X86_LOCAL_APIC
1082 bool "Local APIC support on uniprocessors" if !PCI_MSI
1084 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1086 A local APIC (Advanced Programmable Interrupt Controller) is an
1087 integrated interrupt controller in the CPU. If you have a single-CPU
1088 system which has a processor with a local APIC, you can say Y here to
1089 enable and use it. If you say Y here even though your machine doesn't
1090 have a local APIC, then the kernel will still run with no slowdown at
1091 all. The local APIC supports CPU-generated self-interrupts (timer,
1092 performance counters), and the NMI watchdog which detects hard
1095 config X86_UP_IOAPIC
1096 bool "IO-APIC support on uniprocessors"
1097 depends on X86_UP_APIC
1099 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1100 SMP-capable replacement for PC-style interrupt controllers. Most
1101 SMP systems and many recent uniprocessor systems have one.
1103 If you have a single-CPU system with an IO-APIC, you can say Y here
1104 to use it. If you say Y here even though your machine doesn't have
1105 an IO-APIC, then the kernel will still run with no slowdown at all.
1107 config X86_LOCAL_APIC
1109 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1110 select IRQ_DOMAIN_HIERARCHY
1114 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1116 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1117 bool "Reroute for broken boot IRQs"
1118 depends on X86_IO_APIC
1120 This option enables a workaround that fixes a source of
1121 spurious interrupts. This is recommended when threaded
1122 interrupt handling is used on systems where the generation of
1123 superfluous "boot interrupts" cannot be disabled.
1125 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1126 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1127 kernel does during interrupt handling). On chipsets where this
1128 boot IRQ generation cannot be disabled, this workaround keeps
1129 the original IRQ line masked so that only the equivalent "boot
1130 IRQ" is delivered to the CPUs. The workaround also tells the
1131 kernel to set up the IRQ handler on the boot IRQ line. In this
1132 way only one interrupt is delivered to the kernel. Otherwise
1133 the spurious second interrupt may cause the kernel to bring
1134 down (vital) interrupt lines.
1136 Only affects "broken" chipsets. Interrupt sharing may be
1137 increased on these systems.
1140 bool "Machine Check / overheating reporting"
1141 select GENERIC_ALLOCATOR
1144 Machine Check support allows the processor to notify the
1145 kernel if it detects a problem (e.g. overheating, data corruption).
1146 The action the kernel takes depends on the severity of the problem,
1147 ranging from warning messages to halting the machine.
1149 config X86_MCELOG_LEGACY
1150 bool "Support for deprecated /dev/mcelog character device"
1153 Enable support for /dev/mcelog which is needed by the old mcelog
1154 userspace logging daemon. Consider switching to the new generation
1157 config X86_MCE_INTEL
1159 prompt "Intel MCE features"
1160 depends on X86_MCE && X86_LOCAL_APIC
1162 Additional support for intel specific MCE features such as
1163 the thermal monitor.
1167 prompt "AMD MCE features"
1168 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1170 Additional support for AMD specific MCE features such as
1171 the DRAM Error Threshold.
1173 config X86_ANCIENT_MCE
1174 bool "Support for old Pentium 5 / WinChip machine checks"
1175 depends on X86_32 && X86_MCE
1177 Include support for machine check handling on old Pentium 5 or WinChip
1178 systems. These typically need to be enabled explicitly on the command
1181 config X86_MCE_THRESHOLD
1182 depends on X86_MCE_AMD || X86_MCE_INTEL
1185 config X86_MCE_INJECT
1186 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1187 tristate "Machine check injector support"
1189 Provide support for injecting machine checks for testing purposes.
1190 If you don't know what a machine check is and you don't do kernel
1191 QA it is safe to say n.
1193 source "arch/x86/events/Kconfig"
1195 config X86_LEGACY_VM86
1196 bool "Legacy VM86 support"
1199 This option allows user programs to put the CPU into V8086
1200 mode, which is an 80286-era approximation of 16-bit real mode.
1202 Some very old versions of X and/or vbetool require this option
1203 for user mode setting. Similarly, DOSEMU will use it if
1204 available to accelerate real mode DOS programs. However, any
1205 recent version of DOSEMU, X, or vbetool should be fully
1206 functional even without kernel VM86 support, as they will all
1207 fall back to software emulation. Nevertheless, if you are using
1208 a 16-bit DOS program where 16-bit performance matters, vm86
1209 mode might be faster than emulation and you might want to
1212 Note that any app that works on a 64-bit kernel is unlikely to
1213 need this option, as 64-bit kernels don't, and can't, support
1214 V8086 mode. This option is also unrelated to 16-bit protected
1215 mode and is not needed to run most 16-bit programs under Wine.
1217 Enabling this option increases the complexity of the kernel
1218 and slows down exception handling a tiny bit.
1220 If unsure, say N here.
1224 default X86_LEGACY_VM86
1227 bool "Enable support for 16-bit segments" if EXPERT
1229 depends on MODIFY_LDT_SYSCALL
1231 This option is required by programs like Wine to run 16-bit
1232 protected mode legacy code on x86 processors. Disabling
1233 this option saves about 300 bytes on i386, or around 6K text
1234 plus 16K runtime memory on x86-64,
1238 depends on X86_16BIT && X86_32
1242 depends on X86_16BIT && X86_64
1244 config X86_VSYSCALL_EMULATION
1245 bool "Enable vsyscall emulation" if EXPERT
1249 This enables emulation of the legacy vsyscall page. Disabling
1250 it is roughly equivalent to booting with vsyscall=none, except
1251 that it will also disable the helpful warning if a program
1252 tries to use a vsyscall. With this option set to N, offending
1253 programs will just segfault, citing addresses of the form
1256 This option is required by many programs built before 2013, and
1257 care should be used even with newer programs if set to N.
1259 Disabling this option saves about 7K of kernel size and
1260 possibly 4K of additional runtime pagetable memory.
1262 config X86_IOPL_IOPERM
1263 bool "IOPERM and IOPL Emulation"
1266 This enables the ioperm() and iopl() syscalls which are necessary
1267 for legacy applications.
1269 Legacy IOPL support is an overbroad mechanism which allows user
1270 space aside of accessing all 65536 I/O ports also to disable
1271 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1272 capabilities and permission from potentially active security
1275 The emulation restricts the functionality of the syscall to
1276 only allowing the full range I/O port access, but prevents the
1277 ability to disable interrupts from user space which would be
1278 granted if the hardware IOPL mechanism would be used.
1281 tristate "Toshiba Laptop support"
1284 This adds a driver to safely access the System Management Mode of
1285 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1286 not work on models with a Phoenix BIOS. The System Management Mode
1287 is used to set the BIOS and power saving options on Toshiba portables.
1289 For information on utilities to make use of this driver see the
1290 Toshiba Linux utilities web site at:
1291 <http://www.buzzard.org.uk/toshiba/>.
1293 Say Y if you intend to run this kernel on a Toshiba portable.
1296 config X86_REBOOTFIXUPS
1297 bool "Enable X86 board specific fixups for reboot"
1300 This enables chipset and/or board specific fixups to be done
1301 in order to get reboot to work correctly. This is only needed on
1302 some combinations of hardware and BIOS. The symptom, for which
1303 this config is intended, is when reboot ends with a stalled/hung
1306 Currently, the only fixup is for the Geode machines using
1307 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1309 Say Y if you want to enable the fixup. Currently, it's safe to
1310 enable this option even if you don't need it.
1315 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1317 config MICROCODE_INITRD32
1319 depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1321 config MICROCODE_LATE_LOADING
1322 bool "Late microcode loading (DANGEROUS)"
1324 depends on MICROCODE && SMP
1326 Loading microcode late, when the system is up and executing instructions
1327 is a tricky business and should be avoided if possible. Just the sequence
1328 of synchronizing all cores and SMT threads is one fragile dance which does
1329 not guarantee that cores might not softlock after the loading. Therefore,
1330 use this at your own risk. Late loading taints the kernel unless the
1331 microcode header indicates that it is safe for late loading via the
1332 minimal revision check. This minimal revision check can be enforced on
1333 the kernel command line with "microcode.minrev=Y".
1335 config MICROCODE_LATE_FORCE_MINREV
1336 bool "Enforce late microcode loading minimal revision check"
1338 depends on MICROCODE_LATE_LOADING
1340 To prevent that users load microcode late which modifies already
1341 in use features, newer microcode patches have a minimum revision field
1342 in the microcode header, which tells the kernel which minimum
1343 revision must be active in the CPU to safely load that new microcode
1344 late into the running system. If disabled the check will not
1345 be enforced but the kernel will be tainted when the minimal
1346 revision check fails.
1348 This minimal revision check can also be controlled via the
1349 "microcode.minrev" parameter on the kernel command line.
1354 tristate "/dev/cpu/*/msr - Model-specific register support"
1356 This device gives privileged processes access to the x86
1357 Model-Specific Registers (MSRs). It is a character device with
1358 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1359 MSR accesses are directed to a specific CPU on multi-processor
1363 tristate "/dev/cpu/*/cpuid - CPU information support"
1365 This device gives processes access to the x86 CPUID instruction to
1366 be executed on a specific processor. It is a character device
1367 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1371 prompt "High Memory Support"
1378 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1379 However, the address space of 32-bit x86 processors is only 4
1380 Gigabytes large. That means that, if you have a large amount of
1381 physical memory, not all of it can be "permanently mapped" by the
1382 kernel. The physical memory that's not permanently mapped is called
1385 If you are compiling a kernel which will never run on a machine with
1386 more than 1 Gigabyte total physical RAM, answer "off" here (default
1387 choice and suitable for most users). This will result in a "3GB/1GB"
1388 split: 3GB are mapped so that each process sees a 3GB virtual memory
1389 space and the remaining part of the 4GB virtual memory space is used
1390 by the kernel to permanently map as much physical memory as
1393 If the machine has between 1 and 4 Gigabytes physical RAM, then
1396 If more than 4 Gigabytes is used then answer "64GB" here. This
1397 selection turns Intel PAE (Physical Address Extension) mode on.
1398 PAE implements 3-level paging on IA32 processors. PAE is fully
1399 supported by Linux, PAE mode is implemented on all recent Intel
1400 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1401 then the kernel will not boot on CPUs that don't support PAE!
1403 The actual amount of total physical memory will either be
1404 auto detected or can be forced by using a kernel command line option
1405 such as "mem=256M". (Try "man bootparam" or see the documentation of
1406 your boot loader (lilo or loadlin) about how to pass options to the
1407 kernel at boot time.)
1409 If unsure, say "off".
1414 Select this if you have a 32-bit processor and between 1 and 4
1415 gigabytes of physical RAM.
1419 depends on X86_HAVE_PAE
1422 Select this if you have a 32-bit processor and more than 4
1423 gigabytes of physical RAM.
1428 prompt "Memory split" if EXPERT
1432 Select the desired split between kernel and user memory.
1434 If the address range available to the kernel is less than the
1435 physical memory installed, the remaining memory will be available
1436 as "high memory". Accessing high memory is a little more costly
1437 than low memory, as it needs to be mapped into the kernel first.
1438 Note that increasing the kernel address space limits the range
1439 available to user programs, making the address space there
1440 tighter. Selecting anything other than the default 3G/1G split
1441 will also likely make your kernel incompatible with binary-only
1444 If you are not absolutely sure what you are doing, leave this
1448 bool "3G/1G user/kernel split"
1449 config VMSPLIT_3G_OPT
1451 bool "3G/1G user/kernel split (for full 1G low memory)"
1453 bool "2G/2G user/kernel split"
1454 config VMSPLIT_2G_OPT
1456 bool "2G/2G user/kernel split (for full 2G low memory)"
1458 bool "1G/3G user/kernel split"
1463 default 0xB0000000 if VMSPLIT_3G_OPT
1464 default 0x80000000 if VMSPLIT_2G
1465 default 0x78000000 if VMSPLIT_2G_OPT
1466 default 0x40000000 if VMSPLIT_1G
1472 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1475 bool "PAE (Physical Address Extension) Support"
1476 depends on X86_32 && X86_HAVE_PAE
1477 select PHYS_ADDR_T_64BIT
1480 PAE is required for NX support, and furthermore enables
1481 larger swapspace support for non-overcommit purposes. It
1482 has the cost of more pagetable lookup overhead, and also
1483 consumes more pagetable space per process.
1486 bool "Enable 5-level page tables support"
1488 select DYNAMIC_MEMORY_LAYOUT
1489 select SPARSEMEM_VMEMMAP
1492 5-level paging enables access to larger address space:
1493 up to 128 PiB of virtual address space and 4 PiB of
1494 physical address space.
1496 It will be supported by future Intel CPUs.
1498 A kernel with the option enabled can be booted on machines that
1499 support 4- or 5-level paging.
1501 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1506 config X86_DIRECT_GBPAGES
1510 Certain kernel features effectively disable kernel
1511 linear 1 GB mappings (even if the CPU otherwise
1512 supports them), so don't confuse the user by printing
1513 that we have them enabled.
1515 config X86_CPA_STATISTICS
1516 bool "Enable statistic for Change Page Attribute"
1519 Expose statistics about the Change Page Attribute mechanism, which
1520 helps to determine the effectiveness of preserving large and huge
1521 page mappings when mapping protections are changed.
1523 config X86_MEM_ENCRYPT
1524 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1525 select DYNAMIC_PHYSICAL_MASK
1528 config AMD_MEM_ENCRYPT
1529 bool "AMD Secure Memory Encryption (SME) support"
1530 depends on X86_64 && CPU_SUP_AMD
1532 select DMA_COHERENT_POOL
1533 select ARCH_USE_MEMREMAP_PROT
1534 select INSTRUCTION_DECODER
1535 select ARCH_HAS_CC_PLATFORM
1536 select X86_MEM_ENCRYPT
1537 select UNACCEPTED_MEMORY
1539 Say yes to enable support for the encryption of system memory.
1540 This requires an AMD processor that supports Secure Memory
1543 # Common NUMA Features
1545 bool "NUMA Memory Allocation and Scheduler Support"
1547 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1548 default y if X86_BIGSMP
1549 select USE_PERCPU_NUMA_NODE_ID
1550 select OF_NUMA if OF
1552 Enable NUMA (Non-Uniform Memory Access) support.
1554 The kernel will try to allocate memory used by a CPU on the
1555 local memory controller of the CPU and add some more
1556 NUMA awareness to the kernel.
1558 For 64-bit this is recommended if the system is Intel Core i7
1559 (or later), AMD Opteron, or EM64T NUMA.
1561 For 32-bit this is only needed if you boot a 32-bit
1562 kernel on a 64-bit NUMA platform.
1564 Otherwise, you should say N.
1568 prompt "Old style AMD Opteron NUMA detection"
1569 depends on X86_64 && NUMA && PCI
1571 Enable AMD NUMA node topology detection. You should say Y here if
1572 you have a multi processor AMD system. This uses an old method to
1573 read the NUMA configuration directly from the builtin Northbridge
1574 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1575 which also takes priority if both are compiled in.
1577 config X86_64_ACPI_NUMA
1579 prompt "ACPI NUMA detection"
1580 depends on X86_64 && NUMA && ACPI && PCI
1583 Enable ACPI SRAT based node topology detection.
1586 bool "NUMA emulation"
1589 Enable NUMA emulation. A flat machine will be split
1590 into virtual nodes when booted with "numa=fake=N", where N is the
1591 number of nodes. This is only useful for debugging.
1594 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1596 default "10" if MAXSMP
1597 default "6" if X86_64
1601 Specify the maximum number of NUMA Nodes available on the target
1602 system. Increases memory reserved to accommodate various tables.
1604 config ARCH_FLATMEM_ENABLE
1606 depends on X86_32 && !NUMA
1608 config ARCH_SPARSEMEM_ENABLE
1610 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1611 select SPARSEMEM_STATIC if X86_32
1612 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1614 config ARCH_SPARSEMEM_DEFAULT
1615 def_bool X86_64 || (NUMA && X86_32)
1617 config ARCH_SELECT_MEMORY_MODEL
1619 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1621 config ARCH_MEMORY_PROBE
1622 bool "Enable sysfs memory/probe interface"
1623 depends on MEMORY_HOTPLUG
1625 This option enables a sysfs memory/probe interface for testing.
1626 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1627 If you are unsure how to answer this question, answer N.
1629 config ARCH_PROC_KCORE_TEXT
1631 depends on X86_64 && PROC_KCORE
1633 config ILLEGAL_POINTER_VALUE
1636 default 0xdead000000000000 if X86_64
1638 config X86_PMEM_LEGACY_DEVICE
1641 config X86_PMEM_LEGACY
1642 tristate "Support non-standard NVDIMMs and ADR protected memory"
1643 depends on PHYS_ADDR_T_64BIT
1645 select X86_PMEM_LEGACY_DEVICE
1646 select NUMA_KEEP_MEMINFO if NUMA
1649 Treat memory marked using the non-standard e820 type of 12 as used
1650 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1651 The kernel will offer these regions to the 'pmem' driver so
1652 they can be used for persistent storage.
1657 bool "Allocate 3rd-level pagetables from highmem"
1660 The VM uses one page table entry for each page of physical memory.
1661 For systems with a lot of RAM, this can be wasteful of precious
1662 low memory. Setting this option will put user-space page table
1663 entries in high memory.
1665 config X86_CHECK_BIOS_CORRUPTION
1666 bool "Check for low memory corruption"
1668 Periodically check for memory corruption in low memory, which
1669 is suspected to be caused by BIOS. Even when enabled in the
1670 configuration, it is disabled at runtime. Enable it by
1671 setting "memory_corruption_check=1" on the kernel command
1672 line. By default it scans the low 64k of memory every 60
1673 seconds; see the memory_corruption_check_size and
1674 memory_corruption_check_period parameters in
1675 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1677 When enabled with the default parameters, this option has
1678 almost no overhead, as it reserves a relatively small amount
1679 of memory and scans it infrequently. It both detects corruption
1680 and prevents it from affecting the running system.
1682 It is, however, intended as a diagnostic tool; if repeatable
1683 BIOS-originated corruption always affects the same memory,
1684 you can use memmap= to prevent the kernel from using that
1687 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1688 bool "Set the default setting of memory_corruption_check"
1689 depends on X86_CHECK_BIOS_CORRUPTION
1692 Set whether the default state of memory_corruption_check is
1695 config MATH_EMULATION
1697 depends on MODIFY_LDT_SYSCALL
1698 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1700 Linux can emulate a math coprocessor (used for floating point
1701 operations) if you don't have one. 486DX and Pentium processors have
1702 a math coprocessor built in, 486SX and 386 do not, unless you added
1703 a 487DX or 387, respectively. (The messages during boot time can
1704 give you some hints here ["man dmesg"].) Everyone needs either a
1705 coprocessor or this emulation.
1707 If you don't have a math coprocessor, you need to say Y here; if you
1708 say Y here even though you have a coprocessor, the coprocessor will
1709 be used nevertheless. (This behavior can be changed with the kernel
1710 command line option "no387", which comes handy if your coprocessor
1711 is broken. Try "man bootparam" or see the documentation of your boot
1712 loader (lilo or loadlin) about how to pass options to the kernel at
1713 boot time.) This means that it is a good idea to say Y here if you
1714 intend to use this kernel on different machines.
1716 More information about the internals of the Linux math coprocessor
1717 emulation can be found in <file:arch/x86/math-emu/README>.
1719 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1720 kernel, it won't hurt.
1724 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1726 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1727 the Memory Type Range Registers (MTRRs) may be used to control
1728 processor access to memory ranges. This is most useful if you have
1729 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1730 allows bus write transfers to be combined into a larger transfer
1731 before bursting over the PCI/AGP bus. This can increase performance
1732 of image write operations 2.5 times or more. Saying Y here creates a
1733 /proc/mtrr file which may be used to manipulate your processor's
1734 MTRRs. Typically the X server should use this.
1736 This code has a reasonably generic interface so that similar
1737 control registers on other processors can be easily supported
1740 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1741 Registers (ARRs) which provide a similar functionality to MTRRs. For
1742 these, the ARRs are used to emulate the MTRRs.
1743 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1744 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1745 write-combining. All of these processors are supported by this code
1746 and it makes sense to say Y here if you have one of them.
1748 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1749 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1750 can lead to all sorts of problems, so it's good to say Y here.
1752 You can safely say Y even if your machine doesn't have MTRRs, you'll
1753 just add about 9 KB to your kernel.
1755 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1757 config MTRR_SANITIZER
1759 prompt "MTRR cleanup support"
1762 Convert MTRR layout from continuous to discrete, so X drivers can
1763 add writeback entries.
1765 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1766 The largest mtrr entry size for a continuous block can be set with
1771 config MTRR_SANITIZER_ENABLE_DEFAULT
1772 int "MTRR cleanup enable value (0-1)"
1775 depends on MTRR_SANITIZER
1777 Enable mtrr cleanup default value
1779 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1780 int "MTRR cleanup spare reg num (0-7)"
1783 depends on MTRR_SANITIZER
1785 mtrr cleanup spare entries default, it can be changed via
1786 mtrr_spare_reg_nr=N on the kernel command line.
1790 prompt "x86 PAT support" if EXPERT
1793 Use PAT attributes to setup page level cache control.
1795 PATs are the modern equivalents of MTRRs and are much more
1796 flexible than MTRRs.
1798 Say N here if you see bootup problems (boot crash, boot hang,
1799 spontaneous reboots) or a non-working video driver.
1803 config ARCH_USES_PG_UNCACHED
1809 prompt "User Mode Instruction Prevention" if EXPERT
1811 User Mode Instruction Prevention (UMIP) is a security feature in
1812 some x86 processors. If enabled, a general protection fault is
1813 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1814 executed in user mode. These instructions unnecessarily expose
1815 information about the hardware state.
1817 The vast majority of applications do not use these instructions.
1818 For the very few that do, software emulation is provided in
1819 specific cases in protected and virtual-8086 modes. Emulated
1823 # GCC >= 9 and binutils >= 2.29
1824 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1826 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1827 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1828 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1829 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1835 CET features configured (Shadow stack or IBT)
1837 config X86_KERNEL_IBT
1838 prompt "Indirect Branch Tracking"
1840 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1841 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1842 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1846 Build the kernel with support for Indirect Branch Tracking, a
1847 hardware support course-grain forward-edge Control Flow Integrity
1848 protection. It enforces that all indirect calls must land on
1849 an ENDBR instruction, as such, the compiler will instrument the
1850 code with them to make this happen.
1852 In addition to building the kernel with IBT, seal all functions that
1853 are not indirect call targets, avoiding them ever becoming one.
1855 This requires LTO like objtool runs and will slow down the build. It
1856 does significantly reduce the number of ENDBR instructions in the
1859 config X86_INTEL_MEMORY_PROTECTION_KEYS
1860 prompt "Memory Protection Keys"
1862 # Note: only available in 64-bit mode
1863 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1864 select ARCH_USES_HIGH_VMA_FLAGS
1865 select ARCH_HAS_PKEYS
1867 Memory Protection Keys provides a mechanism for enforcing
1868 page-based protections, but without requiring modification of the
1869 page tables when an application changes protection domains.
1871 For details, see Documentation/core-api/protection-keys.rst
1876 prompt "TSX enable mode"
1877 depends on CPU_SUP_INTEL
1878 default X86_INTEL_TSX_MODE_OFF
1880 Intel's TSX (Transactional Synchronization Extensions) feature
1881 allows to optimize locking protocols through lock elision which
1882 can lead to a noticeable performance boost.
1884 On the other hand it has been shown that TSX can be exploited
1885 to form side channel attacks (e.g. TAA) and chances are there
1886 will be more of those attacks discovered in the future.
1888 Therefore TSX is not enabled by default (aka tsx=off). An admin
1889 might override this decision by tsx=on the command line parameter.
1890 Even with TSX enabled, the kernel will attempt to enable the best
1891 possible TAA mitigation setting depending on the microcode available
1892 for the particular machine.
1894 This option allows to set the default tsx mode between tsx=on, =off
1895 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1898 Say off if not sure, auto if TSX is in use but it should be used on safe
1899 platforms or on if TSX is in use and the security aspect of tsx is not
1902 config X86_INTEL_TSX_MODE_OFF
1905 TSX is disabled if possible - equals to tsx=off command line parameter.
1907 config X86_INTEL_TSX_MODE_ON
1910 TSX is always enabled on TSX capable HW - equals the tsx=on command
1913 config X86_INTEL_TSX_MODE_AUTO
1916 TSX is enabled on TSX capable HW that is believed to be safe against
1917 side channel attacks- equals the tsx=auto command line parameter.
1921 bool "Software Guard eXtensions (SGX)"
1922 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1924 depends on CRYPTO_SHA256=y
1926 select NUMA_KEEP_MEMINFO if NUMA
1929 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1930 that can be used by applications to set aside private regions of code
1931 and data, referred to as enclaves. An enclave's private memory can
1932 only be accessed by code running within the enclave. Accesses from
1933 outside the enclave, including other enclaves, are disallowed by
1938 config X86_USER_SHADOW_STACK
1939 bool "X86 userspace shadow stack"
1942 select ARCH_USES_HIGH_VMA_FLAGS
1945 Shadow stack protection is a hardware feature that detects function
1946 return address corruption. This helps mitigate ROP attacks.
1947 Applications must be enabled to use it, and old userspace does not
1948 get protection "for free".
1950 CPUs supporting shadow stacks were first released in 2020.
1952 See Documentation/arch/x86/shstk.rst for more information.
1956 config INTEL_TDX_HOST
1957 bool "Intel Trust Domain Extensions (TDX) host support"
1958 depends on CPU_SUP_INTEL
1960 depends on KVM_INTEL
1961 depends on X86_X2APIC
1962 select ARCH_KEEP_MEMBLOCK
1963 depends on CONTIG_ALLOC
1964 depends on !KEXEC_CORE
1967 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1968 host and certain physical attacks. This option enables necessary TDX
1969 support in the host kernel to run confidential VMs.
1974 bool "EFI runtime service support"
1977 select EFI_RUNTIME_WRAPPERS
1978 select ARCH_USE_MEMREMAP_PROT
1979 select EFI_RUNTIME_MAP if KEXEC_CORE
1981 This enables the kernel to use EFI runtime services that are
1982 available (such as the EFI variable services).
1984 This option is only useful on systems that have EFI firmware.
1985 In addition, you should use the latest ELILO loader available
1986 at <http://elilo.sourceforge.net> in order to take advantage
1987 of EFI runtime services. However, even with this option, the
1988 resultant kernel should continue to boot on existing non-EFI
1992 bool "EFI stub support"
1996 This kernel feature allows a bzImage to be loaded directly
1997 by EFI firmware without the use of a bootloader.
1999 See Documentation/admin-guide/efi-stub.rst for more information.
2001 config EFI_HANDOVER_PROTOCOL
2002 bool "EFI handover protocol (DEPRECATED)"
2006 Select this in order to include support for the deprecated EFI
2007 handover protocol, which defines alternative entry points into the
2008 EFI stub. This is a practice that has no basis in the UEFI
2009 specification, and requires a priori knowledge on the part of the
2010 bootloader about Linux/x86 specific ways of passing the command line
2011 and initrd, and where in memory those assets may be loaded.
2013 If in doubt, say Y. Even though the corresponding support is not
2014 present in upstream GRUB or other bootloaders, most distros build
2015 GRUB with numerous downstream patches applied, and may rely on the
2016 handover protocol as as result.
2019 bool "EFI mixed-mode support"
2020 depends on EFI_STUB && X86_64
2022 Enabling this feature allows a 64-bit kernel to be booted
2023 on a 32-bit firmware, provided that your CPU supports 64-bit
2026 Note that it is not possible to boot a mixed-mode enabled
2027 kernel via the EFI boot stub - a bootloader that supports
2028 the EFI handover protocol must be used.
2032 config EFI_FAKE_MEMMAP
2033 bool "Enable EFI fake memory map"
2036 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2037 this parameter, you can add arbitrary attribute to specific memory
2038 range by updating original (firmware provided) EFI memmap. This is
2039 useful for debugging of EFI memmap related feature, e.g., Address
2040 Range Mirroring feature.
2042 config EFI_MAX_FAKE_MEM
2043 int "maximum allowable number of ranges in efi_fake_mem boot option"
2044 depends on EFI_FAKE_MEMMAP
2048 Maximum allowable number of ranges in efi_fake_mem boot option.
2049 Ranges can be set up to this value using comma-separated list.
2050 The default value is 8.
2052 config EFI_RUNTIME_MAP
2053 bool "Export EFI runtime maps to sysfs" if EXPERT
2056 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2057 That memory map is required by the 2nd kernel to set up EFI virtual
2058 mappings after kexec, but can also be used for debugging purposes.
2060 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2062 source "kernel/Kconfig.hz"
2064 config ARCH_SUPPORTS_KEXEC
2067 config ARCH_SUPPORTS_KEXEC_FILE
2070 config ARCH_SELECTS_KEXEC_FILE
2072 depends on KEXEC_FILE
2073 select HAVE_IMA_KEXEC if IMA
2075 config ARCH_SUPPORTS_KEXEC_PURGATORY
2078 config ARCH_SUPPORTS_KEXEC_SIG
2081 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2084 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2087 config ARCH_SUPPORTS_KEXEC_JUMP
2090 config ARCH_SUPPORTS_CRASH_DUMP
2091 def_bool X86_64 || (X86_32 && HIGHMEM)
2093 config ARCH_SUPPORTS_CRASH_HOTPLUG
2096 config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2099 config PHYSICAL_START
2100 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2103 This gives the physical address where the kernel is loaded.
2105 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2106 bzImage will decompress itself to above physical address and
2107 run from there. Otherwise, bzImage will run from the address where
2108 it has been loaded by the boot loader and will ignore above physical
2111 In normal kdump cases one does not have to set/change this option
2112 as now bzImage can be compiled as a completely relocatable image
2113 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2114 address. This option is mainly useful for the folks who don't want
2115 to use a bzImage for capturing the crash dump and want to use a
2116 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2117 to be specifically compiled to run from a specific memory area
2118 (normally a reserved region) and this option comes handy.
2120 So if you are using bzImage for capturing the crash dump,
2121 leave the value here unchanged to 0x1000000 and set
2122 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2123 for capturing the crash dump change this value to start of
2124 the reserved region. In other words, it can be set based on
2125 the "X" value as specified in the "crashkernel=YM@XM"
2126 command line boot parameter passed to the panic-ed
2127 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2128 for more details about crash dumps.
2130 Usage of bzImage for capturing the crash dump is recommended as
2131 one does not have to build two kernels. Same kernel can be used
2132 as production kernel and capture kernel. Above option should have
2133 gone away after relocatable bzImage support is introduced. But it
2134 is present because there are users out there who continue to use
2135 vmlinux for dump capture. This option should go away down the
2138 Don't change this unless you know what you are doing.
2141 bool "Build a relocatable kernel"
2144 This builds a kernel image that retains relocation information
2145 so it can be loaded someplace besides the default 1MB.
2146 The relocations tend to make the kernel binary about 10% larger,
2147 but are discarded at runtime.
2149 One use is for the kexec on panic case where the recovery kernel
2150 must live at a different physical address than the primary
2153 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2154 it has been loaded at and the compile time physical address
2155 (CONFIG_PHYSICAL_START) is used as the minimum location.
2157 config RANDOMIZE_BASE
2158 bool "Randomize the address of the kernel image (KASLR)"
2159 depends on RELOCATABLE
2162 In support of Kernel Address Space Layout Randomization (KASLR),
2163 this randomizes the physical address at which the kernel image
2164 is decompressed and the virtual address where the kernel
2165 image is mapped, as a security feature that deters exploit
2166 attempts relying on knowledge of the location of kernel
2169 On 64-bit, the kernel physical and virtual addresses are
2170 randomized separately. The physical address will be anywhere
2171 between 16MB and the top of physical memory (up to 64TB). The
2172 virtual address will be randomized from 16MB up to 1GB (9 bits
2173 of entropy). Note that this also reduces the memory space
2174 available to kernel modules from 1.5GB to 1GB.
2176 On 32-bit, the kernel physical and virtual addresses are
2177 randomized together. They will be randomized from 16MB up to
2178 512MB (8 bits of entropy).
2180 Entropy is generated using the RDRAND instruction if it is
2181 supported. If RDTSC is supported, its value is mixed into
2182 the entropy pool as well. If neither RDRAND nor RDTSC are
2183 supported, then entropy is read from the i8254 timer. The
2184 usable entropy is limited by the kernel being built using
2185 2GB addressing, and that PHYSICAL_ALIGN must be at a
2186 minimum of 2MB. As a result, only 10 bits of entropy are
2187 theoretically possible, but the implementations are further
2188 limited due to memory layouts.
2192 # Relocation on x86 needs some additional build support
2193 config X86_NEED_RELOCS
2195 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2197 config PHYSICAL_ALIGN
2198 hex "Alignment value to which kernel should be aligned"
2200 range 0x2000 0x1000000 if X86_32
2201 range 0x200000 0x1000000 if X86_64
2203 This value puts the alignment restrictions on physical address
2204 where kernel is loaded and run from. Kernel is compiled for an
2205 address which meets above alignment restriction.
2207 If bootloader loads the kernel at a non-aligned address and
2208 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2209 address aligned to above value and run from there.
2211 If bootloader loads the kernel at a non-aligned address and
2212 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2213 load address and decompress itself to the address it has been
2214 compiled for and run from there. The address for which kernel is
2215 compiled already meets above alignment restrictions. Hence the
2216 end result is that kernel runs from a physical address meeting
2217 above alignment restrictions.
2219 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2220 this value must be a multiple of 0x200000.
2222 Don't change this unless you know what you are doing.
2224 config DYNAMIC_MEMORY_LAYOUT
2227 This option makes base addresses of vmalloc and vmemmap as well as
2228 __PAGE_OFFSET movable during boot.
2230 config RANDOMIZE_MEMORY
2231 bool "Randomize the kernel memory sections"
2233 depends on RANDOMIZE_BASE
2234 select DYNAMIC_MEMORY_LAYOUT
2235 default RANDOMIZE_BASE
2237 Randomizes the base virtual address of kernel memory sections
2238 (physical memory mapping, vmalloc & vmemmap). This security feature
2239 makes exploits relying on predictable memory locations less reliable.
2241 The order of allocations remains unchanged. Entropy is generated in
2242 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2243 configuration have in average 30,000 different possible virtual
2244 addresses for each memory section.
2248 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2249 hex "Physical memory mapping padding" if EXPERT
2250 depends on RANDOMIZE_MEMORY
2251 default "0xa" if MEMORY_HOTPLUG
2253 range 0x1 0x40 if MEMORY_HOTPLUG
2256 Define the padding in terabytes added to the existing physical
2257 memory size during kernel memory randomization. It is useful
2258 for memory hotplug support but reduces the entropy available for
2259 address randomization.
2261 If unsure, leave at the default value.
2263 config ADDRESS_MASKING
2264 bool "Linear Address Masking support"
2267 Linear Address Masking (LAM) modifies the checking that is applied
2268 to 64-bit linear addresses, allowing software to use of the
2269 untranslated address bits for metadata.
2271 The capability can be used for efficient address sanitizers (ASAN)
2272 implementation and for optimizations in JITs.
2280 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2281 depends on COMPAT_32
2283 Certain buggy versions of glibc will crash if they are
2284 presented with a 32-bit vDSO that is not mapped at the address
2285 indicated in its segment table.
2287 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2288 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2289 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2290 the only released version with the bug, but OpenSUSE 9
2291 contains a buggy "glibc 2.3.2".
2293 The symptom of the bug is that everything crashes on startup, saying:
2294 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2296 Saying Y here changes the default value of the vdso32 boot
2297 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2298 This works around the glibc bug but hurts performance.
2300 If unsure, say N: if you are compiling your own kernel, you
2301 are unlikely to be using a buggy version of glibc.
2304 prompt "vsyscall table for legacy applications"
2306 default LEGACY_VSYSCALL_XONLY
2308 Legacy user code that does not know how to find the vDSO expects
2309 to be able to issue three syscalls by calling fixed addresses in
2310 kernel space. Since this location is not randomized with ASLR,
2311 it can be used to assist security vulnerability exploitation.
2313 This setting can be changed at boot time via the kernel command
2314 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2315 is deprecated and can only be enabled using the kernel command
2318 On a system with recent enough glibc (2.14 or newer) and no
2319 static binaries, you can say None without a performance penalty
2320 to improve security.
2322 If unsure, select "Emulate execution only".
2324 config LEGACY_VSYSCALL_XONLY
2325 bool "Emulate execution only"
2327 The kernel traps and emulates calls into the fixed vsyscall
2328 address mapping and does not allow reads. This
2329 configuration is recommended when userspace might use the
2330 legacy vsyscall area but support for legacy binary
2331 instrumentation of legacy code is not needed. It mitigates
2332 certain uses of the vsyscall area as an ASLR-bypassing
2335 config LEGACY_VSYSCALL_NONE
2338 There will be no vsyscall mapping at all. This will
2339 eliminate any risk of ASLR bypass due to the vsyscall
2340 fixed address mapping. Attempts to use the vsyscalls
2341 will be reported to dmesg, so that either old or
2342 malicious userspace programs can be identified.
2347 bool "Built-in kernel command line"
2349 Allow for specifying boot arguments to the kernel at
2350 build time. On some systems (e.g. embedded ones), it is
2351 necessary or convenient to provide some or all of the
2352 kernel boot arguments with the kernel itself (that is,
2353 to not rely on the boot loader to provide them.)
2355 To compile command line arguments into the kernel,
2356 set this option to 'Y', then fill in the
2357 boot arguments in CONFIG_CMDLINE.
2359 Systems with fully functional boot loaders (i.e. non-embedded)
2360 should leave this option set to 'N'.
2363 string "Built-in kernel command string"
2364 depends on CMDLINE_BOOL
2367 Enter arguments here that should be compiled into the kernel
2368 image and used at boot time. If the boot loader provides a
2369 command line at boot time, it is appended to this string to
2370 form the full kernel command line, when the system boots.
2372 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2373 change this behavior.
2375 In most cases, the command line (whether built-in or provided
2376 by the boot loader) should specify the device for the root
2379 config CMDLINE_OVERRIDE
2380 bool "Built-in command line overrides boot loader arguments"
2381 depends on CMDLINE_BOOL && CMDLINE != ""
2383 Set this option to 'Y' to have the kernel ignore the boot loader
2384 command line, and use ONLY the built-in command line.
2386 This is used to work around broken boot loaders. This should
2387 be set to 'N' under normal conditions.
2389 config MODIFY_LDT_SYSCALL
2390 bool "Enable the LDT (local descriptor table)" if EXPERT
2393 Linux can allow user programs to install a per-process x86
2394 Local Descriptor Table (LDT) using the modify_ldt(2) system
2395 call. This is required to run 16-bit or segmented code such as
2396 DOSEMU or some Wine programs. It is also used by some very old
2397 threading libraries.
2399 Enabling this feature adds a small amount of overhead to
2400 context switches and increases the low-level kernel attack
2401 surface. Disabling it removes the modify_ldt(2) system call.
2403 Saying 'N' here may make sense for embedded or server kernels.
2405 config STRICT_SIGALTSTACK_SIZE
2406 bool "Enforce strict size checking for sigaltstack"
2407 depends on DYNAMIC_SIGFRAME
2409 For historical reasons MINSIGSTKSZ is a constant which became
2410 already too small with AVX512 support. Add a mechanism to
2411 enforce strict checking of the sigaltstack size against the
2412 real size of the FPU frame. This option enables the check
2413 by default. It can also be controlled via the kernel command
2414 line option 'strict_sas_size' independent of this config
2415 switch. Enabling it might break existing applications which
2416 allocate a too small sigaltstack but 'work' because they
2417 never get a signal delivered.
2419 Say 'N' unless you want to really enforce this check.
2421 source "kernel/livepatch/Kconfig"
2426 def_bool $(cc-option,-mharden-sls=all)
2428 config CC_HAS_RETURN_THUNK
2429 def_bool $(cc-option,-mfunction-return=thunk-extern)
2431 config CC_HAS_ENTRY_PADDING
2432 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2434 config FUNCTION_PADDING_CFI
2436 default 59 if FUNCTION_ALIGNMENT_64B
2437 default 27 if FUNCTION_ALIGNMENT_32B
2438 default 11 if FUNCTION_ALIGNMENT_16B
2439 default 3 if FUNCTION_ALIGNMENT_8B
2442 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2443 # except Kconfig can't do arithmetic :/
2444 config FUNCTION_PADDING_BYTES
2446 default FUNCTION_PADDING_CFI if CFI_CLANG
2447 default FUNCTION_ALIGNMENT
2451 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2452 select FUNCTION_ALIGNMENT_16B
2456 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2459 config HAVE_CALL_THUNKS
2461 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2467 config PREFIX_SYMBOLS
2469 depends on CALL_PADDING && !CFI_CLANG
2471 menuconfig CPU_MITIGATIONS
2472 bool "Mitigations for CPU vulnerabilities"
2475 Say Y here to enable options which enable mitigations for hardware
2476 vulnerabilities (usually related to speculative execution).
2478 If you say N, all mitigations will be disabled. You really
2479 should know what you are doing to say so.
2483 config PAGE_TABLE_ISOLATION
2484 bool "Remove the kernel mapping in user mode"
2486 depends on (X86_64 || X86_PAE)
2488 This feature reduces the number of hardware side channels by
2489 ensuring that the majority of kernel addresses are not mapped
2492 See Documentation/arch/x86/pti.rst for more details.
2495 bool "Avoid speculative indirect branches in kernel"
2496 select OBJTOOL if HAVE_OBJTOOL
2499 Compile kernel with the retpoline compiler options to guard against
2500 kernel-to-user data leaks by avoiding speculative indirect
2501 branches. Requires a compiler with -mindirect-branch=thunk-extern
2502 support for full protection. The kernel may run slower.
2505 bool "Enable return-thunks"
2506 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2507 select OBJTOOL if HAVE_OBJTOOL
2510 Compile the kernel with the return-thunks compiler option to guard
2511 against kernel-to-user data leaks by avoiding return speculation.
2512 Requires a compiler with -mfunction-return=thunk-extern
2513 support for full protection. The kernel may run slower.
2515 config CPU_UNRET_ENTRY
2516 bool "Enable UNRET on kernel entry"
2517 depends on CPU_SUP_AMD && RETHUNK && X86_64
2520 Compile the kernel with support for the retbleed=unret mitigation.
2522 config CALL_DEPTH_TRACKING
2523 bool "Mitigate RSB underflow with call depth tracking"
2524 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2525 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2529 Compile the kernel with call depth tracking to mitigate the Intel
2530 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2531 mitigation is off by default and needs to be enabled on the
2532 kernel command line via the retbleed=stuff option. For
2533 non-affected systems the overhead of this option is marginal as
2534 the call depth tracking is using run-time generated call thunks
2535 in a compiler generated padding area and call patching. This
2536 increases text size by ~5%. For non affected systems this space
2537 is unused. On affected SKL systems this results in a significant
2538 performance gain over the IBRS mitigation.
2540 config CALL_THUNKS_DEBUG
2541 bool "Enable call thunks and call depth tracking debugging"
2542 depends on CALL_DEPTH_TRACKING
2543 select FUNCTION_ALIGNMENT_32B
2546 Enable call/ret counters for imbalance detection and build in
2547 a noisy dmesg about callthunks generation and call patching for
2548 trouble shooting. The debug prints need to be enabled on the
2549 kernel command line with 'debug-callthunks'.
2550 Only enable this when you are debugging call thunks as this
2551 creates a noticeable runtime overhead. If unsure say N.
2553 config CPU_IBPB_ENTRY
2554 bool "Enable IBPB on kernel entry"
2555 depends on CPU_SUP_AMD && X86_64
2558 Compile the kernel with support for the retbleed=ibpb mitigation.
2560 config CPU_IBRS_ENTRY
2561 bool "Enable IBRS on kernel entry"
2562 depends on CPU_SUP_INTEL && X86_64
2565 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2566 This mitigates both spectre_v2 and retbleed at great cost to
2570 bool "Mitigate speculative RAS overflow on AMD"
2571 depends on CPU_SUP_AMD && X86_64 && RETHUNK
2574 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2577 bool "Mitigate Straight-Line-Speculation"
2578 depends on CC_HAS_SLS && X86_64
2579 select OBJTOOL if HAVE_OBJTOOL
2582 Compile the kernel with straight-line-speculation options to guard
2583 against straight line speculation. The kernel image might be slightly
2586 config GDS_FORCE_MITIGATION
2587 bool "Force GDS Mitigation"
2588 depends on CPU_SUP_INTEL
2591 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2592 unprivileged speculative access to data which was previously stored in
2595 This option is equivalent to setting gather_data_sampling=force on the
2596 command line. The microcode mitigation is used if present, otherwise
2597 AVX is disabled as a mitigation. On affected systems that are missing
2598 the microcode any userspace code that unconditionally uses AVX will
2599 break with this option set.
2601 Setting this option on systems not vulnerable to GDS has no effect.
2605 config MITIGATION_RFDS
2606 bool "RFDS Mitigation"
2607 depends on CPU_SUP_INTEL
2610 Enable mitigation for Register File Data Sampling (RFDS) by default.
2611 RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2612 allows unprivileged speculative access to stale data previously
2613 stored in floating point, vector and integer registers.
2614 See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2616 config MITIGATION_SPECTRE_BHI
2617 bool "Mitigate Spectre-BHB (Branch History Injection)"
2618 depends on CPU_SUP_INTEL
2621 Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2622 where the branch history buffer is poisoned to speculatively steer
2624 See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
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"