1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_SUPPORTS_PER_VMA_LOCK
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
63 select ARCH_32BIT_OFF_T if X86_32
64 select ARCH_CLOCKSOURCE_INIT
65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
72 select ARCH_HAS_CACHE_LINE_SIZE
73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
74 select ARCH_HAS_CPU_FINALIZE_INIT
75 select ARCH_HAS_CPU_PASID if IOMMU_SVA
76 select ARCH_HAS_CURRENT_STACK_POINTER
77 select ARCH_HAS_DEBUG_VIRTUAL
78 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
79 select ARCH_HAS_DEVMEM_IS_ALLOWED
80 select ARCH_HAS_EARLY_DEBUG if KGDB
81 select ARCH_HAS_ELF_RANDOMIZE
82 select ARCH_HAS_FAST_MULTIPLIER
83 select ARCH_HAS_FORTIFY_SOURCE
84 select ARCH_HAS_GCOV_PROFILE_ALL
85 select ARCH_HAS_KCOV if X86_64
86 select ARCH_HAS_MEM_ENCRYPT
87 select ARCH_HAS_MEMBARRIER_SYNC_CORE
88 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
89 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
90 select ARCH_HAS_PMEM_API if X86_64
91 select ARCH_HAS_PTE_DEVMAP if X86_64
92 select ARCH_HAS_PTE_SPECIAL
93 select ARCH_HAS_HW_PTE_YOUNG
94 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
95 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
96 select ARCH_HAS_COPY_MC if X86_64
97 select ARCH_HAS_SET_MEMORY
98 select ARCH_HAS_SET_DIRECT_MAP
99 select ARCH_HAS_STRICT_KERNEL_RWX
100 select ARCH_HAS_STRICT_MODULE_RWX
101 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
102 select ARCH_HAS_SYSCALL_WRAPPER
103 select ARCH_HAS_UBSAN_SANITIZE_ALL
104 select ARCH_HAS_DEBUG_WX
105 select ARCH_HAS_ZONE_DMA_SET if EXPERT
106 select ARCH_HAVE_NMI_SAFE_CMPXCHG
107 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
108 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
109 select ARCH_MIGHT_HAVE_PC_PARPORT
110 select ARCH_MIGHT_HAVE_PC_SERIO
111 select ARCH_STACKWALK
112 select ARCH_SUPPORTS_ACPI
113 select ARCH_SUPPORTS_ATOMIC_RMW
114 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
115 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
116 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
117 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
118 select ARCH_SUPPORTS_CFI_CLANG if X86_64
119 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
120 select ARCH_SUPPORTS_LTO_CLANG
121 select ARCH_SUPPORTS_LTO_CLANG_THIN
122 select ARCH_USE_BUILTIN_BSWAP
123 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
124 select ARCH_USE_MEMTEST
125 select ARCH_USE_QUEUED_RWLOCKS
126 select ARCH_USE_QUEUED_SPINLOCKS
127 select ARCH_USE_SYM_ANNOTATIONS
128 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
129 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
130 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
131 select ARCH_WANTS_NO_INSTR
132 select ARCH_WANT_GENERAL_HUGETLB
133 select ARCH_WANT_HUGE_PMD_SHARE
134 select ARCH_WANT_LD_ORPHAN_WARN
135 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
136 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
137 select ARCH_WANTS_THP_SWAP if X86_64
138 select ARCH_HAS_PARANOID_L1D_FLUSH
139 select BUILDTIME_TABLE_SORT
141 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
142 select CLOCKSOURCE_WATCHDOG
143 # Word-size accesses may read uninitialized data past the trailing \0
144 # in strings and cause false KMSAN reports.
145 select DCACHE_WORD_ACCESS if !KMSAN
146 select DYNAMIC_SIGFRAME
147 select EDAC_ATOMIC_SCRUB
149 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
150 select GENERIC_CLOCKEVENTS_MIN_ADJUST
151 select GENERIC_CMOS_UPDATE
152 select GENERIC_CPU_AUTOPROBE
153 select GENERIC_CPU_DEVICES
154 select GENERIC_CPU_VULNERABILITIES
155 select GENERIC_EARLY_IOREMAP
158 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
159 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
160 select GENERIC_IRQ_MIGRATION if SMP
161 select GENERIC_IRQ_PROBE
162 select GENERIC_IRQ_RESERVATION_MODE
163 select GENERIC_IRQ_SHOW
164 select GENERIC_PENDING_IRQ if SMP
165 select GENERIC_PTDUMP
166 select GENERIC_SMP_IDLE_THREAD
167 select GENERIC_TIME_VSYSCALL
168 select GENERIC_GETTIMEOFDAY
169 select GENERIC_VDSO_TIME_NS
170 select GUP_GET_PXX_LOW_HIGH if X86_PAE
171 select HARDIRQS_SW_RESEND
172 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
174 select HAVE_ACPI_APEI if ACPI
175 select HAVE_ACPI_APEI_NMI if ACPI
176 select HAVE_ALIGNED_STRUCT_PAGE
177 select HAVE_ARCH_AUDITSYSCALL
178 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
179 select HAVE_ARCH_HUGE_VMALLOC if X86_64
180 select HAVE_ARCH_JUMP_LABEL
181 select HAVE_ARCH_JUMP_LABEL_RELATIVE
182 select HAVE_ARCH_KASAN if X86_64
183 select HAVE_ARCH_KASAN_VMALLOC if X86_64
184 select HAVE_ARCH_KFENCE
185 select HAVE_ARCH_KMSAN if X86_64
186 select HAVE_ARCH_KGDB
187 select HAVE_ARCH_MMAP_RND_BITS if MMU
188 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
189 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
190 select HAVE_ARCH_PREL32_RELOCATIONS
191 select HAVE_ARCH_SECCOMP_FILTER
192 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
193 select HAVE_ARCH_STACKLEAK
194 select HAVE_ARCH_TRACEHOOK
195 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
196 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
197 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
198 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
199 select HAVE_ARCH_VMAP_STACK if X86_64
200 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
201 select HAVE_ARCH_WITHIN_STACK_FRAMES
202 select HAVE_ASM_MODVERSIONS
203 select HAVE_CMPXCHG_DOUBLE
204 select HAVE_CMPXCHG_LOCAL
205 select HAVE_CONTEXT_TRACKING_USER if X86_64
206 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
207 select HAVE_C_RECORDMCOUNT
208 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
209 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
210 select HAVE_BUILDTIME_MCOUNT_SORT
211 select HAVE_DEBUG_KMEMLEAK
212 select HAVE_DMA_CONTIGUOUS
213 select HAVE_DYNAMIC_FTRACE
214 select HAVE_DYNAMIC_FTRACE_WITH_REGS
215 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
216 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
217 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
218 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
220 select HAVE_EFFICIENT_UNALIGNED_ACCESS
222 select HAVE_EXIT_THREAD
224 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
225 select HAVE_FTRACE_MCOUNT_RECORD
226 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
227 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
228 select HAVE_FUNCTION_TRACER
229 select HAVE_GCC_PLUGINS
230 select HAVE_HW_BREAKPOINT
231 select HAVE_IOREMAP_PROT
232 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
233 select HAVE_IRQ_TIME_ACCOUNTING
234 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
235 select HAVE_KERNEL_BZIP2
236 select HAVE_KERNEL_GZIP
237 select HAVE_KERNEL_LZ4
238 select HAVE_KERNEL_LZMA
239 select HAVE_KERNEL_LZO
240 select HAVE_KERNEL_XZ
241 select HAVE_KERNEL_ZSTD
243 select HAVE_KPROBES_ON_FTRACE
244 select HAVE_FUNCTION_ERROR_INJECTION
245 select HAVE_KRETPROBES
248 select HAVE_LIVEPATCH if X86_64
249 select HAVE_MIXED_BREAKPOINTS_REGS
250 select HAVE_MOD_ARCH_SPECIFIC
253 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
255 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
256 select HAVE_OBJTOOL if X86_64
257 select HAVE_OPTPROBES
258 select HAVE_PAGE_SIZE_4KB
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 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1544 bool "Activate AMD Secure Memory Encryption (SME) by default"
1545 depends on AMD_MEM_ENCRYPT
1547 Say yes to have system memory encrypted by default if running on
1548 an AMD processor that supports Secure Memory Encryption (SME).
1550 If set to Y, then the encryption of system memory can be
1551 deactivated with the mem_encrypt=off command line option.
1553 If set to N, then the encryption of system memory can be
1554 activated with the mem_encrypt=on command line option.
1556 # Common NUMA Features
1558 bool "NUMA Memory Allocation and Scheduler Support"
1560 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1561 default y if X86_BIGSMP
1562 select USE_PERCPU_NUMA_NODE_ID
1563 select OF_NUMA if OF
1565 Enable NUMA (Non-Uniform Memory Access) support.
1567 The kernel will try to allocate memory used by a CPU on the
1568 local memory controller of the CPU and add some more
1569 NUMA awareness to the kernel.
1571 For 64-bit this is recommended if the system is Intel Core i7
1572 (or later), AMD Opteron, or EM64T NUMA.
1574 For 32-bit this is only needed if you boot a 32-bit
1575 kernel on a 64-bit NUMA platform.
1577 Otherwise, you should say N.
1581 prompt "Old style AMD Opteron NUMA detection"
1582 depends on X86_64 && NUMA && PCI
1584 Enable AMD NUMA node topology detection. You should say Y here if
1585 you have a multi processor AMD system. This uses an old method to
1586 read the NUMA configuration directly from the builtin Northbridge
1587 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1588 which also takes priority if both are compiled in.
1590 config X86_64_ACPI_NUMA
1592 prompt "ACPI NUMA detection"
1593 depends on X86_64 && NUMA && ACPI && PCI
1596 Enable ACPI SRAT based node topology detection.
1599 bool "NUMA emulation"
1602 Enable NUMA emulation. A flat machine will be split
1603 into virtual nodes when booted with "numa=fake=N", where N is the
1604 number of nodes. This is only useful for debugging.
1607 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1609 default "10" if MAXSMP
1610 default "6" if X86_64
1614 Specify the maximum number of NUMA Nodes available on the target
1615 system. Increases memory reserved to accommodate various tables.
1617 config ARCH_FLATMEM_ENABLE
1619 depends on X86_32 && !NUMA
1621 config ARCH_SPARSEMEM_ENABLE
1623 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1624 select SPARSEMEM_STATIC if X86_32
1625 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1627 config ARCH_SPARSEMEM_DEFAULT
1628 def_bool X86_64 || (NUMA && X86_32)
1630 config ARCH_SELECT_MEMORY_MODEL
1632 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1634 config ARCH_MEMORY_PROBE
1635 bool "Enable sysfs memory/probe interface"
1636 depends on MEMORY_HOTPLUG
1638 This option enables a sysfs memory/probe interface for testing.
1639 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1640 If you are unsure how to answer this question, answer N.
1642 config ARCH_PROC_KCORE_TEXT
1644 depends on X86_64 && PROC_KCORE
1646 config ILLEGAL_POINTER_VALUE
1649 default 0xdead000000000000 if X86_64
1651 config X86_PMEM_LEGACY_DEVICE
1654 config X86_PMEM_LEGACY
1655 tristate "Support non-standard NVDIMMs and ADR protected memory"
1656 depends on PHYS_ADDR_T_64BIT
1658 select X86_PMEM_LEGACY_DEVICE
1659 select NUMA_KEEP_MEMINFO if NUMA
1662 Treat memory marked using the non-standard e820 type of 12 as used
1663 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1664 The kernel will offer these regions to the 'pmem' driver so
1665 they can be used for persistent storage.
1670 bool "Allocate 3rd-level pagetables from highmem"
1673 The VM uses one page table entry for each page of physical memory.
1674 For systems with a lot of RAM, this can be wasteful of precious
1675 low memory. Setting this option will put user-space page table
1676 entries in high memory.
1678 config X86_CHECK_BIOS_CORRUPTION
1679 bool "Check for low memory corruption"
1681 Periodically check for memory corruption in low memory, which
1682 is suspected to be caused by BIOS. Even when enabled in the
1683 configuration, it is disabled at runtime. Enable it by
1684 setting "memory_corruption_check=1" on the kernel command
1685 line. By default it scans the low 64k of memory every 60
1686 seconds; see the memory_corruption_check_size and
1687 memory_corruption_check_period parameters in
1688 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1690 When enabled with the default parameters, this option has
1691 almost no overhead, as it reserves a relatively small amount
1692 of memory and scans it infrequently. It both detects corruption
1693 and prevents it from affecting the running system.
1695 It is, however, intended as a diagnostic tool; if repeatable
1696 BIOS-originated corruption always affects the same memory,
1697 you can use memmap= to prevent the kernel from using that
1700 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1701 bool "Set the default setting of memory_corruption_check"
1702 depends on X86_CHECK_BIOS_CORRUPTION
1705 Set whether the default state of memory_corruption_check is
1708 config MATH_EMULATION
1710 depends on MODIFY_LDT_SYSCALL
1711 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1713 Linux can emulate a math coprocessor (used for floating point
1714 operations) if you don't have one. 486DX and Pentium processors have
1715 a math coprocessor built in, 486SX and 386 do not, unless you added
1716 a 487DX or 387, respectively. (The messages during boot time can
1717 give you some hints here ["man dmesg"].) Everyone needs either a
1718 coprocessor or this emulation.
1720 If you don't have a math coprocessor, you need to say Y here; if you
1721 say Y here even though you have a coprocessor, the coprocessor will
1722 be used nevertheless. (This behavior can be changed with the kernel
1723 command line option "no387", which comes handy if your coprocessor
1724 is broken. Try "man bootparam" or see the documentation of your boot
1725 loader (lilo or loadlin) about how to pass options to the kernel at
1726 boot time.) This means that it is a good idea to say Y here if you
1727 intend to use this kernel on different machines.
1729 More information about the internals of the Linux math coprocessor
1730 emulation can be found in <file:arch/x86/math-emu/README>.
1732 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1733 kernel, it won't hurt.
1737 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1739 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1740 the Memory Type Range Registers (MTRRs) may be used to control
1741 processor access to memory ranges. This is most useful if you have
1742 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1743 allows bus write transfers to be combined into a larger transfer
1744 before bursting over the PCI/AGP bus. This can increase performance
1745 of image write operations 2.5 times or more. Saying Y here creates a
1746 /proc/mtrr file which may be used to manipulate your processor's
1747 MTRRs. Typically the X server should use this.
1749 This code has a reasonably generic interface so that similar
1750 control registers on other processors can be easily supported
1753 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1754 Registers (ARRs) which provide a similar functionality to MTRRs. For
1755 these, the ARRs are used to emulate the MTRRs.
1756 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1757 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1758 write-combining. All of these processors are supported by this code
1759 and it makes sense to say Y here if you have one of them.
1761 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1762 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1763 can lead to all sorts of problems, so it's good to say Y here.
1765 You can safely say Y even if your machine doesn't have MTRRs, you'll
1766 just add about 9 KB to your kernel.
1768 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1770 config MTRR_SANITIZER
1772 prompt "MTRR cleanup support"
1775 Convert MTRR layout from continuous to discrete, so X drivers can
1776 add writeback entries.
1778 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1779 The largest mtrr entry size for a continuous block can be set with
1784 config MTRR_SANITIZER_ENABLE_DEFAULT
1785 int "MTRR cleanup enable value (0-1)"
1788 depends on MTRR_SANITIZER
1790 Enable mtrr cleanup default value
1792 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1793 int "MTRR cleanup spare reg num (0-7)"
1796 depends on MTRR_SANITIZER
1798 mtrr cleanup spare entries default, it can be changed via
1799 mtrr_spare_reg_nr=N on the kernel command line.
1803 prompt "x86 PAT support" if EXPERT
1806 Use PAT attributes to setup page level cache control.
1808 PATs are the modern equivalents of MTRRs and are much more
1809 flexible than MTRRs.
1811 Say N here if you see bootup problems (boot crash, boot hang,
1812 spontaneous reboots) or a non-working video driver.
1816 config ARCH_USES_PG_UNCACHED
1822 prompt "User Mode Instruction Prevention" if EXPERT
1824 User Mode Instruction Prevention (UMIP) is a security feature in
1825 some x86 processors. If enabled, a general protection fault is
1826 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1827 executed in user mode. These instructions unnecessarily expose
1828 information about the hardware state.
1830 The vast majority of applications do not use these instructions.
1831 For the very few that do, software emulation is provided in
1832 specific cases in protected and virtual-8086 modes. Emulated
1836 # GCC >= 9 and binutils >= 2.29
1837 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1839 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1840 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1841 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1842 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1848 CET features configured (Shadow stack or IBT)
1850 config X86_KERNEL_IBT
1851 prompt "Indirect Branch Tracking"
1853 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1854 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1855 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1859 Build the kernel with support for Indirect Branch Tracking, a
1860 hardware support course-grain forward-edge Control Flow Integrity
1861 protection. It enforces that all indirect calls must land on
1862 an ENDBR instruction, as such, the compiler will instrument the
1863 code with them to make this happen.
1865 In addition to building the kernel with IBT, seal all functions that
1866 are not indirect call targets, avoiding them ever becoming one.
1868 This requires LTO like objtool runs and will slow down the build. It
1869 does significantly reduce the number of ENDBR instructions in the
1872 config X86_INTEL_MEMORY_PROTECTION_KEYS
1873 prompt "Memory Protection Keys"
1875 # Note: only available in 64-bit mode
1876 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1877 select ARCH_USES_HIGH_VMA_FLAGS
1878 select ARCH_HAS_PKEYS
1880 Memory Protection Keys provides a mechanism for enforcing
1881 page-based protections, but without requiring modification of the
1882 page tables when an application changes protection domains.
1884 For details, see Documentation/core-api/protection-keys.rst
1889 prompt "TSX enable mode"
1890 depends on CPU_SUP_INTEL
1891 default X86_INTEL_TSX_MODE_OFF
1893 Intel's TSX (Transactional Synchronization Extensions) feature
1894 allows to optimize locking protocols through lock elision which
1895 can lead to a noticeable performance boost.
1897 On the other hand it has been shown that TSX can be exploited
1898 to form side channel attacks (e.g. TAA) and chances are there
1899 will be more of those attacks discovered in the future.
1901 Therefore TSX is not enabled by default (aka tsx=off). An admin
1902 might override this decision by tsx=on the command line parameter.
1903 Even with TSX enabled, the kernel will attempt to enable the best
1904 possible TAA mitigation setting depending on the microcode available
1905 for the particular machine.
1907 This option allows to set the default tsx mode between tsx=on, =off
1908 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1911 Say off if not sure, auto if TSX is in use but it should be used on safe
1912 platforms or on if TSX is in use and the security aspect of tsx is not
1915 config X86_INTEL_TSX_MODE_OFF
1918 TSX is disabled if possible - equals to tsx=off command line parameter.
1920 config X86_INTEL_TSX_MODE_ON
1923 TSX is always enabled on TSX capable HW - equals the tsx=on command
1926 config X86_INTEL_TSX_MODE_AUTO
1929 TSX is enabled on TSX capable HW that is believed to be safe against
1930 side channel attacks- equals the tsx=auto command line parameter.
1934 bool "Software Guard eXtensions (SGX)"
1935 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1937 depends on CRYPTO_SHA256=y
1939 select NUMA_KEEP_MEMINFO if NUMA
1942 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1943 that can be used by applications to set aside private regions of code
1944 and data, referred to as enclaves. An enclave's private memory can
1945 only be accessed by code running within the enclave. Accesses from
1946 outside the enclave, including other enclaves, are disallowed by
1951 config X86_USER_SHADOW_STACK
1952 bool "X86 userspace shadow stack"
1955 select ARCH_USES_HIGH_VMA_FLAGS
1958 Shadow stack protection is a hardware feature that detects function
1959 return address corruption. This helps mitigate ROP attacks.
1960 Applications must be enabled to use it, and old userspace does not
1961 get protection "for free".
1963 CPUs supporting shadow stacks were first released in 2020.
1965 See Documentation/arch/x86/shstk.rst for more information.
1969 config INTEL_TDX_HOST
1970 bool "Intel Trust Domain Extensions (TDX) host support"
1971 depends on CPU_SUP_INTEL
1973 depends on KVM_INTEL
1974 depends on X86_X2APIC
1975 select ARCH_KEEP_MEMBLOCK
1976 depends on CONTIG_ALLOC
1977 depends on !KEXEC_CORE
1980 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1981 host and certain physical attacks. This option enables necessary TDX
1982 support in the host kernel to run confidential VMs.
1987 bool "EFI runtime service support"
1990 select EFI_RUNTIME_WRAPPERS
1991 select ARCH_USE_MEMREMAP_PROT
1992 select EFI_RUNTIME_MAP if KEXEC_CORE
1994 This enables the kernel to use EFI runtime services that are
1995 available (such as the EFI variable services).
1997 This option is only useful on systems that have EFI firmware.
1998 In addition, you should use the latest ELILO loader available
1999 at <http://elilo.sourceforge.net> in order to take advantage
2000 of EFI runtime services. However, even with this option, the
2001 resultant kernel should continue to boot on existing non-EFI
2005 bool "EFI stub support"
2009 This kernel feature allows a bzImage to be loaded directly
2010 by EFI firmware without the use of a bootloader.
2012 See Documentation/admin-guide/efi-stub.rst for more information.
2014 config EFI_HANDOVER_PROTOCOL
2015 bool "EFI handover protocol (DEPRECATED)"
2019 Select this in order to include support for the deprecated EFI
2020 handover protocol, which defines alternative entry points into the
2021 EFI stub. This is a practice that has no basis in the UEFI
2022 specification, and requires a priori knowledge on the part of the
2023 bootloader about Linux/x86 specific ways of passing the command line
2024 and initrd, and where in memory those assets may be loaded.
2026 If in doubt, say Y. Even though the corresponding support is not
2027 present in upstream GRUB or other bootloaders, most distros build
2028 GRUB with numerous downstream patches applied, and may rely on the
2029 handover protocol as as result.
2032 bool "EFI mixed-mode support"
2033 depends on EFI_STUB && X86_64
2035 Enabling this feature allows a 64-bit kernel to be booted
2036 on a 32-bit firmware, provided that your CPU supports 64-bit
2039 Note that it is not possible to boot a mixed-mode enabled
2040 kernel via the EFI boot stub - a bootloader that supports
2041 the EFI handover protocol must be used.
2045 config EFI_FAKE_MEMMAP
2046 bool "Enable EFI fake memory map"
2049 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2050 this parameter, you can add arbitrary attribute to specific memory
2051 range by updating original (firmware provided) EFI memmap. This is
2052 useful for debugging of EFI memmap related feature, e.g., Address
2053 Range Mirroring feature.
2055 config EFI_MAX_FAKE_MEM
2056 int "maximum allowable number of ranges in efi_fake_mem boot option"
2057 depends on EFI_FAKE_MEMMAP
2061 Maximum allowable number of ranges in efi_fake_mem boot option.
2062 Ranges can be set up to this value using comma-separated list.
2063 The default value is 8.
2065 config EFI_RUNTIME_MAP
2066 bool "Export EFI runtime maps to sysfs" if EXPERT
2069 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2070 That memory map is required by the 2nd kernel to set up EFI virtual
2071 mappings after kexec, but can also be used for debugging purposes.
2073 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2075 source "kernel/Kconfig.hz"
2077 config ARCH_SUPPORTS_KEXEC
2080 config ARCH_SUPPORTS_KEXEC_FILE
2083 config ARCH_SELECTS_KEXEC_FILE
2085 depends on KEXEC_FILE
2086 select HAVE_IMA_KEXEC if IMA
2088 config ARCH_SUPPORTS_KEXEC_PURGATORY
2091 config ARCH_SUPPORTS_KEXEC_SIG
2094 config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2097 config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2100 config ARCH_SUPPORTS_KEXEC_JUMP
2103 config ARCH_SUPPORTS_CRASH_DUMP
2104 def_bool X86_64 || (X86_32 && HIGHMEM)
2106 config ARCH_SUPPORTS_CRASH_HOTPLUG
2109 config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2112 config PHYSICAL_START
2113 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2116 This gives the physical address where the kernel is loaded.
2118 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2119 bzImage will decompress itself to above physical address and
2120 run from there. Otherwise, bzImage will run from the address where
2121 it has been loaded by the boot loader and will ignore above physical
2124 In normal kdump cases one does not have to set/change this option
2125 as now bzImage can be compiled as a completely relocatable image
2126 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2127 address. This option is mainly useful for the folks who don't want
2128 to use a bzImage for capturing the crash dump and want to use a
2129 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2130 to be specifically compiled to run from a specific memory area
2131 (normally a reserved region) and this option comes handy.
2133 So if you are using bzImage for capturing the crash dump,
2134 leave the value here unchanged to 0x1000000 and set
2135 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2136 for capturing the crash dump change this value to start of
2137 the reserved region. In other words, it can be set based on
2138 the "X" value as specified in the "crashkernel=YM@XM"
2139 command line boot parameter passed to the panic-ed
2140 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2141 for more details about crash dumps.
2143 Usage of bzImage for capturing the crash dump is recommended as
2144 one does not have to build two kernels. Same kernel can be used
2145 as production kernel and capture kernel. Above option should have
2146 gone away after relocatable bzImage support is introduced. But it
2147 is present because there are users out there who continue to use
2148 vmlinux for dump capture. This option should go away down the
2151 Don't change this unless you know what you are doing.
2154 bool "Build a relocatable kernel"
2157 This builds a kernel image that retains relocation information
2158 so it can be loaded someplace besides the default 1MB.
2159 The relocations tend to make the kernel binary about 10% larger,
2160 but are discarded at runtime.
2162 One use is for the kexec on panic case where the recovery kernel
2163 must live at a different physical address than the primary
2166 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2167 it has been loaded at and the compile time physical address
2168 (CONFIG_PHYSICAL_START) is used as the minimum location.
2170 config RANDOMIZE_BASE
2171 bool "Randomize the address of the kernel image (KASLR)"
2172 depends on RELOCATABLE
2175 In support of Kernel Address Space Layout Randomization (KASLR),
2176 this randomizes the physical address at which the kernel image
2177 is decompressed and the virtual address where the kernel
2178 image is mapped, as a security feature that deters exploit
2179 attempts relying on knowledge of the location of kernel
2182 On 64-bit, the kernel physical and virtual addresses are
2183 randomized separately. The physical address will be anywhere
2184 between 16MB and the top of physical memory (up to 64TB). The
2185 virtual address will be randomized from 16MB up to 1GB (9 bits
2186 of entropy). Note that this also reduces the memory space
2187 available to kernel modules from 1.5GB to 1GB.
2189 On 32-bit, the kernel physical and virtual addresses are
2190 randomized together. They will be randomized from 16MB up to
2191 512MB (8 bits of entropy).
2193 Entropy is generated using the RDRAND instruction if it is
2194 supported. If RDTSC is supported, its value is mixed into
2195 the entropy pool as well. If neither RDRAND nor RDTSC are
2196 supported, then entropy is read from the i8254 timer. The
2197 usable entropy is limited by the kernel being built using
2198 2GB addressing, and that PHYSICAL_ALIGN must be at a
2199 minimum of 2MB. As a result, only 10 bits of entropy are
2200 theoretically possible, but the implementations are further
2201 limited due to memory layouts.
2205 # Relocation on x86 needs some additional build support
2206 config X86_NEED_RELOCS
2208 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2210 config PHYSICAL_ALIGN
2211 hex "Alignment value to which kernel should be aligned"
2213 range 0x2000 0x1000000 if X86_32
2214 range 0x200000 0x1000000 if X86_64
2216 This value puts the alignment restrictions on physical address
2217 where kernel is loaded and run from. Kernel is compiled for an
2218 address which meets above alignment restriction.
2220 If bootloader loads the kernel at a non-aligned address and
2221 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2222 address aligned to above value and run from there.
2224 If bootloader loads the kernel at a non-aligned address and
2225 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2226 load address and decompress itself to the address it has been
2227 compiled for and run from there. The address for which kernel is
2228 compiled already meets above alignment restrictions. Hence the
2229 end result is that kernel runs from a physical address meeting
2230 above alignment restrictions.
2232 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2233 this value must be a multiple of 0x200000.
2235 Don't change this unless you know what you are doing.
2237 config DYNAMIC_MEMORY_LAYOUT
2240 This option makes base addresses of vmalloc and vmemmap as well as
2241 __PAGE_OFFSET movable during boot.
2243 config RANDOMIZE_MEMORY
2244 bool "Randomize the kernel memory sections"
2246 depends on RANDOMIZE_BASE
2247 select DYNAMIC_MEMORY_LAYOUT
2248 default RANDOMIZE_BASE
2250 Randomizes the base virtual address of kernel memory sections
2251 (physical memory mapping, vmalloc & vmemmap). This security feature
2252 makes exploits relying on predictable memory locations less reliable.
2254 The order of allocations remains unchanged. Entropy is generated in
2255 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2256 configuration have in average 30,000 different possible virtual
2257 addresses for each memory section.
2261 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2262 hex "Physical memory mapping padding" if EXPERT
2263 depends on RANDOMIZE_MEMORY
2264 default "0xa" if MEMORY_HOTPLUG
2266 range 0x1 0x40 if MEMORY_HOTPLUG
2269 Define the padding in terabytes added to the existing physical
2270 memory size during kernel memory randomization. It is useful
2271 for memory hotplug support but reduces the entropy available for
2272 address randomization.
2274 If unsure, leave at the default value.
2276 config ADDRESS_MASKING
2277 bool "Linear Address Masking support"
2280 Linear Address Masking (LAM) modifies the checking that is applied
2281 to 64-bit linear addresses, allowing software to use of the
2282 untranslated address bits for metadata.
2284 The capability can be used for efficient address sanitizers (ASAN)
2285 implementation and for optimizations in JITs.
2293 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2294 depends on COMPAT_32
2296 Certain buggy versions of glibc will crash if they are
2297 presented with a 32-bit vDSO that is not mapped at the address
2298 indicated in its segment table.
2300 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2301 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2302 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2303 the only released version with the bug, but OpenSUSE 9
2304 contains a buggy "glibc 2.3.2".
2306 The symptom of the bug is that everything crashes on startup, saying:
2307 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2309 Saying Y here changes the default value of the vdso32 boot
2310 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2311 This works around the glibc bug but hurts performance.
2313 If unsure, say N: if you are compiling your own kernel, you
2314 are unlikely to be using a buggy version of glibc.
2317 prompt "vsyscall table for legacy applications"
2319 default LEGACY_VSYSCALL_XONLY
2321 Legacy user code that does not know how to find the vDSO expects
2322 to be able to issue three syscalls by calling fixed addresses in
2323 kernel space. Since this location is not randomized with ASLR,
2324 it can be used to assist security vulnerability exploitation.
2326 This setting can be changed at boot time via the kernel command
2327 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2328 is deprecated and can only be enabled using the kernel command
2331 On a system with recent enough glibc (2.14 or newer) and no
2332 static binaries, you can say None without a performance penalty
2333 to improve security.
2335 If unsure, select "Emulate execution only".
2337 config LEGACY_VSYSCALL_XONLY
2338 bool "Emulate execution only"
2340 The kernel traps and emulates calls into the fixed vsyscall
2341 address mapping and does not allow reads. This
2342 configuration is recommended when userspace might use the
2343 legacy vsyscall area but support for legacy binary
2344 instrumentation of legacy code is not needed. It mitigates
2345 certain uses of the vsyscall area as an ASLR-bypassing
2348 config LEGACY_VSYSCALL_NONE
2351 There will be no vsyscall mapping at all. This will
2352 eliminate any risk of ASLR bypass due to the vsyscall
2353 fixed address mapping. Attempts to use the vsyscalls
2354 will be reported to dmesg, so that either old or
2355 malicious userspace programs can be identified.
2360 bool "Built-in kernel command line"
2362 Allow for specifying boot arguments to the kernel at
2363 build time. On some systems (e.g. embedded ones), it is
2364 necessary or convenient to provide some or all of the
2365 kernel boot arguments with the kernel itself (that is,
2366 to not rely on the boot loader to provide them.)
2368 To compile command line arguments into the kernel,
2369 set this option to 'Y', then fill in the
2370 boot arguments in CONFIG_CMDLINE.
2372 Systems with fully functional boot loaders (i.e. non-embedded)
2373 should leave this option set to 'N'.
2376 string "Built-in kernel command string"
2377 depends on CMDLINE_BOOL
2380 Enter arguments here that should be compiled into the kernel
2381 image and used at boot time. If the boot loader provides a
2382 command line at boot time, it is appended to this string to
2383 form the full kernel command line, when the system boots.
2385 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2386 change this behavior.
2388 In most cases, the command line (whether built-in or provided
2389 by the boot loader) should specify the device for the root
2392 config CMDLINE_OVERRIDE
2393 bool "Built-in command line overrides boot loader arguments"
2394 depends on CMDLINE_BOOL && CMDLINE != ""
2396 Set this option to 'Y' to have the kernel ignore the boot loader
2397 command line, and use ONLY the built-in command line.
2399 This is used to work around broken boot loaders. This should
2400 be set to 'N' under normal conditions.
2402 config MODIFY_LDT_SYSCALL
2403 bool "Enable the LDT (local descriptor table)" if EXPERT
2406 Linux can allow user programs to install a per-process x86
2407 Local Descriptor Table (LDT) using the modify_ldt(2) system
2408 call. This is required to run 16-bit or segmented code such as
2409 DOSEMU or some Wine programs. It is also used by some very old
2410 threading libraries.
2412 Enabling this feature adds a small amount of overhead to
2413 context switches and increases the low-level kernel attack
2414 surface. Disabling it removes the modify_ldt(2) system call.
2416 Saying 'N' here may make sense for embedded or server kernels.
2418 config STRICT_SIGALTSTACK_SIZE
2419 bool "Enforce strict size checking for sigaltstack"
2420 depends on DYNAMIC_SIGFRAME
2422 For historical reasons MINSIGSTKSZ is a constant which became
2423 already too small with AVX512 support. Add a mechanism to
2424 enforce strict checking of the sigaltstack size against the
2425 real size of the FPU frame. This option enables the check
2426 by default. It can also be controlled via the kernel command
2427 line option 'strict_sas_size' independent of this config
2428 switch. Enabling it might break existing applications which
2429 allocate a too small sigaltstack but 'work' because they
2430 never get a signal delivered.
2432 Say 'N' unless you want to really enforce this check.
2434 source "kernel/livepatch/Kconfig"
2439 def_bool $(cc-option,-mharden-sls=all)
2441 config CC_HAS_RETURN_THUNK
2442 def_bool $(cc-option,-mfunction-return=thunk-extern)
2444 config CC_HAS_ENTRY_PADDING
2445 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2447 config FUNCTION_PADDING_CFI
2449 default 59 if FUNCTION_ALIGNMENT_64B
2450 default 27 if FUNCTION_ALIGNMENT_32B
2451 default 11 if FUNCTION_ALIGNMENT_16B
2452 default 3 if FUNCTION_ALIGNMENT_8B
2455 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2456 # except Kconfig can't do arithmetic :/
2457 config FUNCTION_PADDING_BYTES
2459 default FUNCTION_PADDING_CFI if CFI_CLANG
2460 default FUNCTION_ALIGNMENT
2464 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2465 select FUNCTION_ALIGNMENT_16B
2469 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2472 config HAVE_CALL_THUNKS
2474 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2480 config PREFIX_SYMBOLS
2482 depends on CALL_PADDING && !CFI_CLANG
2484 menuconfig SPECULATION_MITIGATIONS
2485 bool "Mitigations for speculative execution vulnerabilities"
2488 Say Y here to enable options which enable mitigations for
2489 speculative execution hardware vulnerabilities.
2491 If you say N, all mitigations will be disabled. You really
2492 should know what you are doing to say so.
2494 if SPECULATION_MITIGATIONS
2496 config PAGE_TABLE_ISOLATION
2497 bool "Remove the kernel mapping in user mode"
2499 depends on (X86_64 || X86_PAE)
2501 This feature reduces the number of hardware side channels by
2502 ensuring that the majority of kernel addresses are not mapped
2505 See Documentation/arch/x86/pti.rst for more details.
2508 bool "Avoid speculative indirect branches in kernel"
2509 select OBJTOOL if HAVE_OBJTOOL
2512 Compile kernel with the retpoline compiler options to guard against
2513 kernel-to-user data leaks by avoiding speculative indirect
2514 branches. Requires a compiler with -mindirect-branch=thunk-extern
2515 support for full protection. The kernel may run slower.
2518 bool "Enable return-thunks"
2519 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2520 select OBJTOOL if HAVE_OBJTOOL
2523 Compile the kernel with the return-thunks compiler option to guard
2524 against kernel-to-user data leaks by avoiding return speculation.
2525 Requires a compiler with -mfunction-return=thunk-extern
2526 support for full protection. The kernel may run slower.
2528 config CPU_UNRET_ENTRY
2529 bool "Enable UNRET on kernel entry"
2530 depends on CPU_SUP_AMD && RETHUNK && X86_64
2533 Compile the kernel with support for the retbleed=unret mitigation.
2535 config CALL_DEPTH_TRACKING
2536 bool "Mitigate RSB underflow with call depth tracking"
2537 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2538 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2542 Compile the kernel with call depth tracking to mitigate the Intel
2543 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2544 mitigation is off by default and needs to be enabled on the
2545 kernel command line via the retbleed=stuff option. For
2546 non-affected systems the overhead of this option is marginal as
2547 the call depth tracking is using run-time generated call thunks
2548 in a compiler generated padding area and call patching. This
2549 increases text size by ~5%. For non affected systems this space
2550 is unused. On affected SKL systems this results in a significant
2551 performance gain over the IBRS mitigation.
2553 config CALL_THUNKS_DEBUG
2554 bool "Enable call thunks and call depth tracking debugging"
2555 depends on CALL_DEPTH_TRACKING
2556 select FUNCTION_ALIGNMENT_32B
2559 Enable call/ret counters for imbalance detection and build in
2560 a noisy dmesg about callthunks generation and call patching for
2561 trouble shooting. The debug prints need to be enabled on the
2562 kernel command line with 'debug-callthunks'.
2563 Only enable this when you are debugging call thunks as this
2564 creates a noticeable runtime overhead. If unsure say N.
2566 config CPU_IBPB_ENTRY
2567 bool "Enable IBPB on kernel entry"
2568 depends on CPU_SUP_AMD && X86_64
2571 Compile the kernel with support for the retbleed=ibpb mitigation.
2573 config CPU_IBRS_ENTRY
2574 bool "Enable IBRS on kernel entry"
2575 depends on CPU_SUP_INTEL && X86_64
2578 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2579 This mitigates both spectre_v2 and retbleed at great cost to
2583 bool "Mitigate speculative RAS overflow on AMD"
2584 depends on CPU_SUP_AMD && X86_64 && RETHUNK
2587 Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2590 bool "Mitigate Straight-Line-Speculation"
2591 depends on CC_HAS_SLS && X86_64
2592 select OBJTOOL if HAVE_OBJTOOL
2595 Compile the kernel with straight-line-speculation options to guard
2596 against straight line speculation. The kernel image might be slightly
2599 config GDS_FORCE_MITIGATION
2600 bool "Force GDS Mitigation"
2601 depends on CPU_SUP_INTEL
2604 Gather Data Sampling (GDS) is a hardware vulnerability which allows
2605 unprivileged speculative access to data which was previously stored in
2608 This option is equivalent to setting gather_data_sampling=force on the
2609 command line. The microcode mitigation is used if present, otherwise
2610 AVX is disabled as a mitigation. On affected systems that are missing
2611 the microcode any userspace code that unconditionally uses AVX will
2612 break with this option set.
2614 Setting this option on systems not vulnerable to GDS has no effect.
2620 config ARCH_HAS_ADD_PAGES
2622 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2624 menu "Power management and ACPI options"
2626 config ARCH_HIBERNATION_HEADER
2628 depends on HIBERNATION
2630 source "kernel/power/Kconfig"
2632 source "drivers/acpi/Kconfig"
2639 tristate "APM (Advanced Power Management) BIOS support"
2640 depends on X86_32 && PM_SLEEP
2642 APM is a BIOS specification for saving power using several different
2643 techniques. This is mostly useful for battery powered laptops with
2644 APM compliant BIOSes. If you say Y here, the system time will be
2645 reset after a RESUME operation, the /proc/apm device will provide
2646 battery status information, and user-space programs will receive
2647 notification of APM "events" (e.g. battery status change).
2649 If you select "Y" here, you can disable actual use of the APM
2650 BIOS by passing the "apm=off" option to the kernel at boot time.
2652 Note that the APM support is almost completely disabled for
2653 machines with more than one CPU.
2655 In order to use APM, you will need supporting software. For location
2656 and more information, read <file:Documentation/power/apm-acpi.rst>
2657 and the Battery Powered Linux mini-HOWTO, available from
2658 <http://www.tldp.org/docs.html#howto>.
2660 This driver does not spin down disk drives (see the hdparm(8)
2661 manpage ("man 8 hdparm") for that), and it doesn't turn off
2662 VESA-compliant "green" monitors.
2664 This driver does not support the TI 4000M TravelMate and the ACER
2665 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2666 desktop machines also don't have compliant BIOSes, and this driver
2667 may cause those machines to panic during the boot phase.
2669 Generally, if you don't have a battery in your machine, there isn't
2670 much point in using this driver and you should say N. If you get
2671 random kernel OOPSes or reboots that don't seem to be related to
2672 anything, try disabling/enabling this option (or disabling/enabling
2675 Some other things you should try when experiencing seemingly random,
2678 1) make sure that you have enough swap space and that it is
2680 2) pass the "idle=poll" option to the kernel
2681 3) switch on floating point emulation in the kernel and pass
2682 the "no387" option to the kernel
2683 4) pass the "floppy=nodma" option to the kernel
2684 5) pass the "mem=4M" option to the kernel (thereby disabling
2685 all but the first 4 MB of RAM)
2686 6) make sure that the CPU is not over clocked.
2687 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2688 8) disable the cache from your BIOS settings
2689 9) install a fan for the video card or exchange video RAM
2690 10) install a better fan for the CPU
2691 11) exchange RAM chips
2692 12) exchange the motherboard.
2694 To compile this driver as a module, choose M here: the
2695 module will be called apm.
2699 config APM_IGNORE_USER_SUSPEND
2700 bool "Ignore USER SUSPEND"
2702 This option will ignore USER SUSPEND requests. On machines with a
2703 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2704 series notebooks, it is necessary to say Y because of a BIOS bug.
2706 config APM_DO_ENABLE
2707 bool "Enable PM at boot time"
2709 Enable APM features at boot time. From page 36 of the APM BIOS
2710 specification: "When disabled, the APM BIOS does not automatically
2711 power manage devices, enter the Standby State, enter the Suspend
2712 State, or take power saving steps in response to CPU Idle calls."
2713 This driver will make CPU Idle calls when Linux is idle (unless this
2714 feature is turned off -- see "Do CPU IDLE calls", below). This
2715 should always save battery power, but more complicated APM features
2716 will be dependent on your BIOS implementation. You may need to turn
2717 this option off if your computer hangs at boot time when using APM
2718 support, or if it beeps continuously instead of suspending. Turn
2719 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2720 T400CDT. This is off by default since most machines do fine without
2725 bool "Make CPU Idle calls when idle"
2727 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2728 On some machines, this can activate improved power savings, such as
2729 a slowed CPU clock rate, when the machine is idle. These idle calls
2730 are made after the idle loop has run for some length of time (e.g.,
2731 333 mS). On some machines, this will cause a hang at boot time or
2732 whenever the CPU becomes idle. (On machines with more than one CPU,
2733 this option does nothing.)
2735 config APM_DISPLAY_BLANK
2736 bool "Enable console blanking using APM"
2738 Enable console blanking using the APM. Some laptops can use this to
2739 turn off the LCD backlight when the screen blanker of the Linux
2740 virtual console blanks the screen. Note that this is only used by
2741 the virtual console screen blanker, and won't turn off the backlight
2742 when using the X Window system. This also doesn't have anything to
2743 do with your VESA-compliant power-saving monitor. Further, this
2744 option doesn't work for all laptops -- it might not turn off your
2745 backlight at all, or it might print a lot of errors to the console,
2746 especially if you are using gpm.
2748 config APM_ALLOW_INTS
2749 bool "Allow interrupts during APM BIOS calls"
2751 Normally we disable external interrupts while we are making calls to
2752 the APM BIOS as a measure to lessen the effects of a badly behaving
2753 BIOS implementation. The BIOS should reenable interrupts if it
2754 needs to. Unfortunately, some BIOSes do not -- especially those in
2755 many of the newer IBM Thinkpads. If you experience hangs when you
2756 suspend, try setting this to Y. Otherwise, say N.
2760 source "drivers/cpufreq/Kconfig"
2762 source "drivers/cpuidle/Kconfig"
2764 source "drivers/idle/Kconfig"
2768 menu "Bus options (PCI etc.)"
2771 prompt "PCI access mode"
2772 depends on X86_32 && PCI
2775 On PCI systems, the BIOS can be used to detect the PCI devices and
2776 determine their configuration. However, some old PCI motherboards
2777 have BIOS bugs and may crash if this is done. Also, some embedded
2778 PCI-based systems don't have any BIOS at all. Linux can also try to
2779 detect the PCI hardware directly without using the BIOS.
2781 With this option, you can specify how Linux should detect the
2782 PCI devices. If you choose "BIOS", the BIOS will be used,
2783 if you choose "Direct", the BIOS won't be used, and if you
2784 choose "MMConfig", then PCI Express MMCONFIG will be used.
2785 If you choose "Any", the kernel will try MMCONFIG, then the
2786 direct access method and falls back to the BIOS if that doesn't
2787 work. If unsure, go with the default, which is "Any".
2792 config PCI_GOMMCONFIG
2809 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2811 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2814 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2817 bool "Support mmconfig PCI config space access" if X86_64
2819 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2820 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2824 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2828 depends on PCI && XEN
2830 config MMCONF_FAM10H
2832 depends on X86_64 && PCI_MMCONFIG && ACPI
2834 config PCI_CNB20LE_QUIRK
2835 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2838 Read the PCI windows out of the CNB20LE host bridge. This allows
2839 PCI hotplug to work on systems with the CNB20LE chipset which do
2842 There's no public spec for this chipset, and this functionality
2843 is known to be incomplete.
2845 You should say N unless you know you need this.
2848 bool "ISA bus support on modern systems" if EXPERT
2850 Expose ISA bus device drivers and options available for selection and
2851 configuration. Enable this option if your target machine has an ISA
2852 bus. ISA is an older system, displaced by PCI and newer bus
2853 architectures -- if your target machine is modern, it probably does
2854 not have an ISA bus.
2858 # x86_64 have no ISA slots, but can have ISA-style DMA.
2860 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2863 Enables ISA-style DMA support for devices requiring such controllers.
2871 Find out whether you have ISA slots on your motherboard. ISA is the
2872 name of a bus system, i.e. the way the CPU talks to the other stuff
2873 inside your box. Other bus systems are PCI, EISA, MicroChannel
2874 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2875 newer boards don't support it. If you have ISA, say Y, otherwise N.
2878 tristate "NatSemi SCx200 support"
2880 This provides basic support for National Semiconductor's
2881 (now AMD's) Geode processors. The driver probes for the
2882 PCI-IDs of several on-chip devices, so its a good dependency
2883 for other scx200_* drivers.
2885 If compiled as a module, the driver is named scx200.
2887 config SCx200HR_TIMER
2888 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2892 This driver provides a clocksource built upon the on-chip
2893 27MHz high-resolution timer. Its also a workaround for
2894 NSC Geode SC-1100's buggy TSC, which loses time when the
2895 processor goes idle (as is done by the scheduler). The
2896 other workaround is idle=poll boot option.
2899 bool "One Laptop Per Child support"
2907 Add support for detecting the unique features of the OLPC
2911 bool "OLPC XO-1 Power Management"
2912 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2914 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2917 bool "OLPC XO-1 Real Time Clock"
2918 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2920 Add support for the XO-1 real time clock, which can be used as a
2921 programmable wakeup source.
2924 bool "OLPC XO-1 SCI extras"
2925 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2929 Add support for SCI-based features of the OLPC XO-1 laptop:
2930 - EC-driven system wakeups
2934 - AC adapter status updates
2935 - Battery status updates
2937 config OLPC_XO15_SCI
2938 bool "OLPC XO-1.5 SCI extras"
2939 depends on OLPC && ACPI
2942 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2943 - EC-driven system wakeups
2944 - AC adapter status updates
2945 - Battery status updates
2948 bool "PCEngines ALIX System Support (LED setup)"
2951 This option enables system support for the PCEngines ALIX.
2952 At present this just sets up LEDs for GPIO control on
2953 ALIX2/3/6 boards. However, other system specific setup should
2956 Note: You must still enable the drivers for GPIO and LED support
2957 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2959 Note: You have to set alix.force=1 for boards with Award BIOS.
2962 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2965 This option enables system support for the Soekris Engineering net5501.
2968 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2972 This option enables system support for the Traverse Technologies GEOS.
2975 bool "Technologic Systems TS-5500 platform support"
2977 select CHECK_SIGNATURE
2981 This option enables system support for the Technologic Systems TS-5500.
2987 depends on CPU_SUP_AMD && PCI
2991 menu "Binary Emulations"
2993 config IA32_EMULATION
2994 bool "IA32 Emulation"
2996 select ARCH_WANT_OLD_COMPAT_IPC
2998 select COMPAT_OLD_SIGACTION
3000 Include code to run legacy 32-bit programs under a
3001 64-bit kernel. You should likely turn this on, unless you're
3002 100% sure that you don't have any 32-bit programs left.
3004 config IA32_EMULATION_DEFAULT_DISABLED
3005 bool "IA32 emulation disabled by default"
3007 depends on IA32_EMULATION
3009 Make IA32 emulation disabled by default. This prevents loading 32-bit
3010 processes and access to 32-bit syscalls. If unsure, leave it to its
3014 bool "x32 ABI for 64-bit mode"
3016 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3017 # compressed debug sections to x86_x32 properly:
3018 # https://github.com/ClangBuiltLinux/linux/issues/514
3019 # https://github.com/ClangBuiltLinux/linux/issues/1141
3020 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3022 Include code to run binaries for the x32 native 32-bit ABI
3023 for 64-bit processors. An x32 process gets access to the
3024 full 64-bit register file and wide data path while leaving
3025 pointers at 32 bits for smaller memory footprint.
3029 depends on IA32_EMULATION || X86_32
3031 select OLD_SIGSUSPEND3
3035 depends on IA32_EMULATION || X86_X32_ABI
3037 config COMPAT_FOR_U64_ALIGNMENT
3043 config HAVE_ATOMIC_IOMAP
3047 source "arch/x86/kvm/Kconfig"
3049 source "arch/x86/Kconfig.assembler"