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 ARCH_USE_CMPXCHG_LOCKREF
32 select HAVE_ARCH_SOFT_DIRTY
33 select MODULES_USE_ELF_RELA
34 select NEED_DMA_MAP_STATE
36 select ARCH_HAS_ELFCORE_COMPAT
39 config FORCE_DYNAMIC_FTRACE
42 depends on FUNCTION_TRACER
45 We keep the static function tracing (!DYNAMIC_FTRACE) around
46 in order to test the non static function tracing in the
47 generic code, as other architectures still use it. But we
48 only need to keep it around for x86_64. No need to keep it
49 for x86_32. For x86_32, force DYNAMIC_FTRACE.
53 # ( Note that options that are marked 'if X86_64' could in principle be
54 # ported to 32-bit as well. )
59 # Note: keep this list sorted alphabetically
61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
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_CURRENT_STACK_POINTER
75 select ARCH_HAS_DEBUG_VIRTUAL
76 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
77 select ARCH_HAS_DEVMEM_IS_ALLOWED
78 select ARCH_HAS_EARLY_DEBUG if KGDB
79 select ARCH_HAS_ELF_RANDOMIZE
80 select ARCH_HAS_FAST_MULTIPLIER
81 select ARCH_HAS_FORTIFY_SOURCE
82 select ARCH_HAS_GCOV_PROFILE_ALL
83 select ARCH_HAS_KCOV if X86_64
84 select ARCH_HAS_MEM_ENCRYPT
85 select ARCH_HAS_MEMBARRIER_SYNC_CORE
86 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
87 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
88 select ARCH_HAS_PMEM_API if X86_64
89 select ARCH_HAS_PTE_DEVMAP if X86_64
90 select ARCH_HAS_PTE_SPECIAL
91 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
92 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
93 select ARCH_HAS_COPY_MC if X86_64
94 select ARCH_HAS_SET_MEMORY
95 select ARCH_HAS_SET_DIRECT_MAP
96 select ARCH_HAS_STRICT_KERNEL_RWX
97 select ARCH_HAS_STRICT_MODULE_RWX
98 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
99 select ARCH_HAS_SYSCALL_WRAPPER
100 select ARCH_HAS_UBSAN_SANITIZE_ALL
101 select ARCH_HAS_DEBUG_WX
102 select ARCH_HAS_ZONE_DMA_SET if EXPERT
103 select ARCH_HAVE_NMI_SAFE_CMPXCHG
104 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
105 select ARCH_MIGHT_HAVE_PC_PARPORT
106 select ARCH_MIGHT_HAVE_PC_SERIO
107 select ARCH_STACKWALK
108 select ARCH_SUPPORTS_ACPI
109 select ARCH_SUPPORTS_ATOMIC_RMW
110 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
111 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
112 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
113 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
114 select ARCH_SUPPORTS_CFI_CLANG if X86_64
115 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
116 select ARCH_SUPPORTS_LTO_CLANG
117 select ARCH_SUPPORTS_LTO_CLANG_THIN
118 select ARCH_USE_BUILTIN_BSWAP
119 select ARCH_USE_MEMTEST
120 select ARCH_USE_QUEUED_RWLOCKS
121 select ARCH_USE_QUEUED_SPINLOCKS
122 select ARCH_USE_SYM_ANNOTATIONS
123 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
124 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
125 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
126 select ARCH_WANTS_NO_INSTR
127 select ARCH_WANT_GENERAL_HUGETLB
128 select ARCH_WANT_HUGE_PMD_SHARE
129 select ARCH_WANT_LD_ORPHAN_WARN
130 select ARCH_WANT_OPTIMIZE_VMEMMAP if X86_64
131 select ARCH_WANTS_THP_SWAP if X86_64
132 select ARCH_HAS_PARANOID_L1D_FLUSH
133 select BUILDTIME_TABLE_SORT
135 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
136 select CLOCKSOURCE_WATCHDOG
137 # Word-size accesses may read uninitialized data past the trailing \0
138 # in strings and cause false KMSAN reports.
139 select DCACHE_WORD_ACCESS if !KMSAN
140 select DYNAMIC_SIGFRAME
141 select EDAC_ATOMIC_SCRUB
143 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
144 select GENERIC_CLOCKEVENTS_MIN_ADJUST
145 select GENERIC_CMOS_UPDATE
146 select GENERIC_CPU_AUTOPROBE
147 select GENERIC_CPU_VULNERABILITIES
148 select GENERIC_EARLY_IOREMAP
151 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
152 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
153 select GENERIC_IRQ_MIGRATION if SMP
154 select GENERIC_IRQ_PROBE
155 select GENERIC_IRQ_RESERVATION_MODE
156 select GENERIC_IRQ_SHOW
157 select GENERIC_PENDING_IRQ if SMP
158 select GENERIC_PTDUMP
159 select GENERIC_SMP_IDLE_THREAD
160 select GENERIC_TIME_VSYSCALL
161 select GENERIC_GETTIMEOFDAY
162 select GENERIC_VDSO_TIME_NS
163 select GUP_GET_PXX_LOW_HIGH if X86_PAE
164 select HARDIRQS_SW_RESEND
165 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
167 select HAVE_ACPI_APEI if ACPI
168 select HAVE_ACPI_APEI_NMI if ACPI
169 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
170 select HAVE_ARCH_AUDITSYSCALL
171 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
172 select HAVE_ARCH_HUGE_VMALLOC if X86_64
173 select HAVE_ARCH_JUMP_LABEL
174 select HAVE_ARCH_JUMP_LABEL_RELATIVE
175 select HAVE_ARCH_KASAN if X86_64
176 select HAVE_ARCH_KASAN_VMALLOC if X86_64
177 select HAVE_ARCH_KFENCE
178 select HAVE_ARCH_KMSAN if X86_64
179 select HAVE_ARCH_KGDB
180 select HAVE_ARCH_MMAP_RND_BITS if MMU
181 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
182 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
183 select HAVE_ARCH_PREL32_RELOCATIONS
184 select HAVE_ARCH_SECCOMP_FILTER
185 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
186 select HAVE_ARCH_STACKLEAK
187 select HAVE_ARCH_TRACEHOOK
188 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
189 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
190 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
191 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
192 select HAVE_ARCH_VMAP_STACK if X86_64
193 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
194 select HAVE_ARCH_WITHIN_STACK_FRAMES
195 select HAVE_ASM_MODVERSIONS
196 select HAVE_CMPXCHG_DOUBLE
197 select HAVE_CMPXCHG_LOCAL
198 select HAVE_CONTEXT_TRACKING_USER if X86_64
199 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
200 select HAVE_C_RECORDMCOUNT
201 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
202 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
203 select HAVE_BUILDTIME_MCOUNT_SORT
204 select HAVE_DEBUG_KMEMLEAK
205 select HAVE_DMA_CONTIGUOUS
206 select HAVE_DYNAMIC_FTRACE
207 select HAVE_DYNAMIC_FTRACE_WITH_REGS
208 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
209 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
210 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
211 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
213 select HAVE_EFFICIENT_UNALIGNED_ACCESS
215 select HAVE_EXIT_THREAD
217 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
218 select HAVE_FTRACE_MCOUNT_RECORD
219 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
220 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
221 select HAVE_FUNCTION_TRACER
222 select HAVE_GCC_PLUGINS
223 select HAVE_HW_BREAKPOINT
224 select HAVE_IOREMAP_PROT
225 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
226 select HAVE_IRQ_TIME_ACCOUNTING
227 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
228 select HAVE_KERNEL_BZIP2
229 select HAVE_KERNEL_GZIP
230 select HAVE_KERNEL_LZ4
231 select HAVE_KERNEL_LZMA
232 select HAVE_KERNEL_LZO
233 select HAVE_KERNEL_XZ
234 select HAVE_KERNEL_ZSTD
236 select HAVE_KPROBES_ON_FTRACE
237 select HAVE_FUNCTION_ERROR_INJECTION
238 select HAVE_KRETPROBES
241 select HAVE_LIVEPATCH if X86_64
242 select HAVE_MIXED_BREAKPOINTS_REGS
243 select HAVE_MOD_ARCH_SPECIFIC
246 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
248 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
249 select HAVE_OBJTOOL if X86_64
250 select HAVE_OPTPROBES
251 select HAVE_PCSPKR_PLATFORM
252 select HAVE_PERF_EVENTS
253 select HAVE_PERF_EVENTS_NMI
254 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
256 select HAVE_PERF_REGS
257 select HAVE_PERF_USER_STACK_DUMP
258 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
259 select MMU_GATHER_MERGE_VMAS
260 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
261 select HAVE_REGS_AND_STACK_ACCESS_API
262 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
263 select HAVE_FUNCTION_ARG_ACCESS_API
264 select HAVE_SETUP_PER_CPU_AREA
265 select HAVE_SOFTIRQ_ON_OWN_STACK
266 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
267 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
268 select HAVE_STATIC_CALL
269 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
270 select HAVE_PREEMPT_DYNAMIC_CALL
272 select HAVE_RUST if X86_64
273 select HAVE_SYSCALL_TRACEPOINTS
274 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
275 select HAVE_UNSTABLE_SCHED_CLOCK
276 select HAVE_USER_RETURN_NOTIFIER
277 select HAVE_GENERIC_VDSO
278 select HOTPLUG_SMT if SMP
279 select IRQ_FORCED_THREADING
280 select NEED_PER_CPU_EMBED_FIRST_CHUNK
281 select NEED_PER_CPU_PAGE_FIRST_CHUNK
282 select NEED_SG_DMA_LENGTH
283 select PCI_DOMAINS if PCI
284 select PCI_LOCKLESS_CONFIG if PCI
287 select RTC_MC146818_LIB
289 select SYSCTL_EXCEPTION_TRACE
290 select THREAD_INFO_IN_TASK
291 select TRACE_IRQFLAGS_SUPPORT
292 select TRACE_IRQFLAGS_NMI_SUPPORT
293 select USER_STACKTRACE_SUPPORT
294 select HAVE_ARCH_KCSAN if X86_64
295 select X86_FEATURE_NAMES if PROC_FS
296 select PROC_PID_ARCH_STATUS if PROC_FS
297 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
298 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
299 select FUNCTION_ALIGNMENT_4B
300 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
301 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
303 config INSTRUCTION_DECODER
305 depends on KPROBES || PERF_EVENTS || UPROBES
309 default "elf32-i386" if X86_32
310 default "elf64-x86-64" if X86_64
312 config LOCKDEP_SUPPORT
315 config STACKTRACE_SUPPORT
321 config ARCH_MMAP_RND_BITS_MIN
325 config ARCH_MMAP_RND_BITS_MAX
329 config ARCH_MMAP_RND_COMPAT_BITS_MIN
332 config ARCH_MMAP_RND_COMPAT_BITS_MAX
338 config GENERIC_ISA_DMA
340 depends on ISA_DMA_API
344 default y if KMSAN || KASAN
349 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
351 config GENERIC_BUG_RELATIVE_POINTERS
354 config ARCH_MAY_HAVE_PC_FDC
356 depends on ISA_DMA_API
358 config GENERIC_CALIBRATE_DELAY
361 config ARCH_HAS_CPU_RELAX
364 config ARCH_HIBERNATION_POSSIBLE
367 config ARCH_SUSPEND_POSSIBLE
373 config KASAN_SHADOW_OFFSET
376 default 0xdffffc0000000000
378 config HAVE_INTEL_TXT
380 depends on INTEL_IOMMU && ACPI
384 depends on X86_32 && SMP
388 depends on X86_64 && SMP
390 config ARCH_SUPPORTS_UPROBES
393 config FIX_EARLYCON_MEM
396 config DYNAMIC_PHYSICAL_MASK
399 config PGTABLE_LEVELS
401 default 5 if X86_5LEVEL
406 config CC_HAS_SANE_STACKPROTECTOR
408 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
409 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
411 We have to make sure stack protector is unconditionally disabled if
412 the compiler produces broken code or if it does not let us control
413 the segment on 32-bit kernels.
415 menu "Processor type and features"
418 bool "Symmetric multi-processing support"
420 This enables support for systems with more than one CPU. If you have
421 a system with only one CPU, say N. If you have a system with more
424 If you say N here, the kernel will run on uni- and multiprocessor
425 machines, but will use only one CPU of a multiprocessor machine. If
426 you say Y here, the kernel will run on many, but not all,
427 uniprocessor machines. On a uniprocessor machine, the kernel
428 will run faster if you say N here.
430 Note that if you say Y here and choose architecture "586" or
431 "Pentium" under "Processor family", the kernel will not work on 486
432 architectures. Similarly, multiprocessor kernels for the "PPro"
433 architecture may not work on all Pentium based boards.
435 People using multiprocessor machines who say Y here should also say
436 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
437 Management" code will be disabled if you say Y here.
439 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
440 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
441 <http://www.tldp.org/docs.html#howto>.
443 If you don't know what to do here, say N.
445 config X86_FEATURE_NAMES
446 bool "Processor feature human-readable names" if EMBEDDED
449 This option compiles in a table of x86 feature bits and corresponding
450 names. This is required to support /proc/cpuinfo and a few kernel
451 messages. You can disable this to save space, at the expense of
452 making those few kernel messages show numeric feature bits instead.
457 bool "Support x2apic"
458 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
460 This enables x2apic support on CPUs that have this feature.
462 This allows 32-bit apic IDs (so it can support very large systems),
463 and accesses the local apic via MSRs not via mmio.
465 Some Intel systems circa 2022 and later are locked into x2APIC mode
466 and can not fall back to the legacy APIC modes if SGX or TDX are
467 enabled in the BIOS. They will boot with very reduced functionality
468 without enabling this option.
470 If you don't know what to do here, say N.
473 bool "Enable MPS table" if ACPI
475 depends on X86_LOCAL_APIC
477 For old smp systems that do not have proper acpi support. Newer systems
478 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
482 depends on X86_GOLDFISH
484 config X86_CPU_RESCTRL
485 bool "x86 CPU resource control support"
486 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
488 select PROC_CPU_RESCTRL if PROC_FS
490 Enable x86 CPU resource control support.
492 Provide support for the allocation and monitoring of system resources
495 Intel calls this Intel Resource Director Technology
496 (Intel(R) RDT). More information about RDT can be found in the
497 Intel x86 Architecture Software Developer Manual.
499 AMD calls this AMD Platform Quality of Service (AMD QoS).
500 More information about AMD QoS can be found in the AMD64 Technology
501 Platform Quality of Service Extensions manual.
507 bool "Support for big SMP systems with more than 8 CPUs"
510 This option is needed for the systems that have more than 8 CPUs.
512 config X86_EXTENDED_PLATFORM
513 bool "Support for extended (non-PC) x86 platforms"
516 If you disable this option then the kernel will only support
517 standard PC platforms. (which covers the vast majority of
520 If you enable this option then you'll be able to select support
521 for the following (non-PC) 32 bit x86 platforms:
522 Goldfish (Android emulator)
525 SGI 320/540 (Visual Workstation)
526 STA2X11-based (e.g. Northville)
527 Moorestown MID devices
529 If you have one of these systems, or if you want to build a
530 generic distribution kernel, say Y here - otherwise say N.
534 config X86_EXTENDED_PLATFORM
535 bool "Support for extended (non-PC) x86 platforms"
538 If you disable this option then the kernel will only support
539 standard PC platforms. (which covers the vast majority of
542 If you enable this option then you'll be able to select support
543 for the following (non-PC) 64 bit x86 platforms:
548 If you have one of these systems, or if you want to build a
549 generic distribution kernel, say Y here - otherwise say N.
551 # This is an alphabetically sorted list of 64 bit extended platforms
552 # Please maintain the alphabetic order if and when there are additions
554 bool "Numascale NumaChip"
556 depends on X86_EXTENDED_PLATFORM
559 depends on X86_X2APIC
560 depends on PCI_MMCONFIG
562 Adds support for Numascale NumaChip large-SMP systems. Needed to
563 enable more than ~168 cores.
564 If you don't have one of these, you should say N here.
568 select HYPERVISOR_GUEST
570 depends on X86_64 && PCI
571 depends on X86_EXTENDED_PLATFORM
574 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
575 supposed to run on these EM64T-based machines. Only choose this option
576 if you have one of these machines.
579 bool "SGI Ultraviolet"
581 depends on X86_EXTENDED_PLATFORM
584 depends on KEXEC_CORE
585 depends on X86_X2APIC
588 This option is needed in order to support SGI Ultraviolet systems.
589 If you don't have one of these, you should say N here.
591 # Following is an alphabetically sorted list of 32 bit extended platforms
592 # Please maintain the alphabetic order if and when there are additions
595 bool "Goldfish (Virtual Platform)"
596 depends on X86_EXTENDED_PLATFORM
598 Enable support for the Goldfish virtual platform used primarily
599 for Android development. Unless you are building for the Android
600 Goldfish emulator say N here.
603 bool "CE4100 TV platform"
605 depends on PCI_GODIRECT
606 depends on X86_IO_APIC
608 depends on X86_EXTENDED_PLATFORM
609 select X86_REBOOTFIXUPS
611 select OF_EARLY_FLATTREE
613 Select for the Intel CE media processor (CE4100) SOC.
614 This option compiles in support for the CE4100 SOC for settop
615 boxes and media devices.
618 bool "Intel MID platform support"
619 depends on X86_EXTENDED_PLATFORM
620 depends on X86_PLATFORM_DEVICES
622 depends on X86_64 || (PCI_GOANY && X86_32)
623 depends on X86_IO_APIC
628 Select to build a kernel capable of supporting Intel MID (Mobile
629 Internet Device) platform systems which do not have the PCI legacy
630 interfaces. If you are building for a PC class system say N here.
632 Intel MID platforms are based on an Intel processor and chipset which
633 consume less power than most of the x86 derivatives.
635 config X86_INTEL_QUARK
636 bool "Intel Quark platform support"
638 depends on X86_EXTENDED_PLATFORM
639 depends on X86_PLATFORM_DEVICES
643 depends on X86_IO_APIC
648 Select to include support for Quark X1000 SoC.
649 Say Y here if you have a Quark based system such as the Arduino
650 compatible Intel Galileo.
652 config X86_INTEL_LPSS
653 bool "Intel Low Power Subsystem Support"
654 depends on X86 && ACPI && PCI
659 Select to build support for Intel Low Power Subsystem such as
660 found on Intel Lynxpoint PCH. Selecting this option enables
661 things like clock tree (common clock framework) and pincontrol
662 which are needed by the LPSS peripheral drivers.
664 config X86_AMD_PLATFORM_DEVICE
665 bool "AMD ACPI2Platform devices support"
670 Select to interpret AMD specific ACPI device to platform device
671 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
672 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
673 implemented under PINCTRL subsystem.
676 tristate "Intel SoC IOSF Sideband support for SoC platforms"
679 This option enables sideband register access support for Intel SoC
680 platforms. On these platforms the IOSF sideband is used in lieu of
681 MSR's for some register accesses, mostly but not limited to thermal
682 and power. Drivers may query the availability of this device to
683 determine if they need the sideband in order to work on these
684 platforms. The sideband is available on the following SoC products.
685 This list is not meant to be exclusive.
690 You should say Y if you are running a kernel on one of these SoC's.
692 config IOSF_MBI_DEBUG
693 bool "Enable IOSF sideband access through debugfs"
694 depends on IOSF_MBI && DEBUG_FS
696 Select this option to expose the IOSF sideband access registers (MCR,
697 MDR, MCRX) through debugfs to write and read register information from
698 different units on the SoC. This is most useful for obtaining device
699 state information for debug and analysis. As this is a general access
700 mechanism, users of this option would have specific knowledge of the
701 device they want to access.
703 If you don't require the option or are in doubt, say N.
706 bool "RDC R-321x SoC"
708 depends on X86_EXTENDED_PLATFORM
710 select X86_REBOOTFIXUPS
712 This option is needed for RDC R-321x system-on-chip, also known
714 If you don't have one of these chips, you should say N here.
716 config X86_32_NON_STANDARD
717 bool "Support non-standard 32-bit SMP architectures"
718 depends on X86_32 && SMP
719 depends on X86_EXTENDED_PLATFORM
721 This option compiles in the bigsmp and STA2X11 default
722 subarchitectures. It is intended for a generic binary
723 kernel. If you select them all, kernel will probe it one by
724 one and will fallback to default.
726 # Alphabetically sorted list of Non standard 32 bit platforms
728 config X86_SUPPORTS_MEMORY_FAILURE
730 # MCE code calls memory_failure():
732 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
733 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
734 depends on X86_64 || !SPARSEMEM
735 select ARCH_SUPPORTS_MEMORY_FAILURE
738 bool "STA2X11 Companion Chip Support"
739 depends on X86_32_NON_STANDARD && PCI
744 This adds support for boards based on the STA2X11 IO-Hub,
745 a.k.a. "ConneXt". The chip is used in place of the standard
746 PC chipset, so all "standard" peripherals are missing. If this
747 option is selected the kernel will still be able to boot on
748 standard PC machines.
751 tristate "Eurobraille/Iris poweroff module"
754 The Iris machines from EuroBraille do not have APM or ACPI support
755 to shut themselves down properly. A special I/O sequence is
756 needed to do so, which is what this module does at
759 This is only for Iris machines from EuroBraille.
763 config SCHED_OMIT_FRAME_POINTER
765 prompt "Single-depth WCHAN output"
768 Calculate simpler /proc/<PID>/wchan values. If this option
769 is disabled then wchan values will recurse back to the
770 caller function. This provides more accurate wchan values,
771 at the expense of slightly more scheduling overhead.
773 If in doubt, say "Y".
775 menuconfig HYPERVISOR_GUEST
776 bool "Linux guest support"
778 Say Y here to enable options for running Linux under various hyper-
779 visors. This option enables basic hypervisor detection and platform
782 If you say N, all options in this submenu will be skipped and
783 disabled, and Linux guest support won't be built in.
788 bool "Enable paravirtualization code"
789 depends on HAVE_STATIC_CALL
791 This changes the kernel so it can modify itself when it is run
792 under a hypervisor, potentially improving performance significantly
793 over full virtualization. However, when run without a hypervisor
794 the kernel is theoretically slower and slightly larger.
799 config PARAVIRT_DEBUG
800 bool "paravirt-ops debugging"
801 depends on PARAVIRT && DEBUG_KERNEL
803 Enable to debug paravirt_ops internals. Specifically, BUG if
804 a paravirt_op is missing when it is called.
806 config PARAVIRT_SPINLOCKS
807 bool "Paravirtualization layer for spinlocks"
808 depends on PARAVIRT && SMP
810 Paravirtualized spinlocks allow a pvops backend to replace the
811 spinlock implementation with something virtualization-friendly
812 (for example, block the virtual CPU rather than spinning).
814 It has a minimal impact on native kernels and gives a nice performance
815 benefit on paravirtualized KVM / Xen kernels.
817 If you are unsure how to answer this question, answer Y.
819 config X86_HV_CALLBACK_VECTOR
822 source "arch/x86/xen/Kconfig"
825 bool "KVM Guest support (including kvmclock)"
827 select PARAVIRT_CLOCK
828 select ARCH_CPUIDLE_HALTPOLL
829 select X86_HV_CALLBACK_VECTOR
832 This option enables various optimizations for running under the KVM
833 hypervisor. It includes a paravirtualized clock, so that instead
834 of relying on a PIT (or probably other) emulation by the
835 underlying device model, the host provides the guest with
836 timing infrastructure such as time of day, and system time
838 config ARCH_CPUIDLE_HALTPOLL
840 prompt "Disable host haltpoll when loading haltpoll driver"
842 If virtualized under KVM, disable host haltpoll.
845 bool "Support for running PVH guests"
847 This option enables the PVH entry point for guest virtual machines
848 as specified in the x86/HVM direct boot ABI.
850 config PARAVIRT_TIME_ACCOUNTING
851 bool "Paravirtual steal time accounting"
854 Select this option to enable fine granularity task steal time
855 accounting. Time spent executing other tasks in parallel with
856 the current vCPU is discounted from the vCPU power. To account for
857 that, there can be a small performance impact.
859 If in doubt, say N here.
861 config PARAVIRT_CLOCK
864 config JAILHOUSE_GUEST
865 bool "Jailhouse non-root cell support"
866 depends on X86_64 && PCI
869 This option allows to run Linux as guest in a Jailhouse non-root
870 cell. You can leave this option disabled if you only want to start
871 Jailhouse and run Linux afterwards in the root cell.
874 bool "ACRN Guest support"
876 select X86_HV_CALLBACK_VECTOR
878 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
879 a flexible, lightweight reference open-source hypervisor, built with
880 real-time and safety-criticality in mind. It is built for embedded
881 IOT with small footprint and real-time features. More details can be
882 found in https://projectacrn.org/.
884 config INTEL_TDX_GUEST
885 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
886 depends on X86_64 && CPU_SUP_INTEL
887 depends on X86_X2APIC
888 select ARCH_HAS_CC_PLATFORM
889 select X86_MEM_ENCRYPT
892 Support running as a guest under Intel TDX. Without this support,
893 the guest kernel can not boot or run under TDX.
894 TDX includes memory encryption and integrity capabilities
895 which protect the confidentiality and integrity of guest
896 memory contents and CPU state. TDX guests are protected from
897 some attacks from the VMM.
899 endif # HYPERVISOR_GUEST
901 source "arch/x86/Kconfig.cpu"
905 prompt "HPET Timer Support" if X86_32
907 Use the IA-PC HPET (High Precision Event Timer) to manage
908 time in preference to the PIT and RTC, if a HPET is
910 HPET is the next generation timer replacing legacy 8254s.
911 The HPET provides a stable time base on SMP
912 systems, unlike the TSC, but it is more expensive to access,
913 as it is off-chip. The interface used is documented
914 in the HPET spec, revision 1.
916 You can safely choose Y here. However, HPET will only be
917 activated if the platform and the BIOS support this feature.
918 Otherwise the 8254 will be used for timing services.
920 Choose N to continue using the legacy 8254 timer.
922 config HPET_EMULATE_RTC
924 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
926 # Mark as expert because too many people got it wrong.
927 # The code disables itself when not needed.
930 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
931 bool "Enable DMI scanning" if EXPERT
933 Enabled scanning of DMI to identify machine quirks. Say Y
934 here unless you have verified that your setup is not
935 affected by entries in the DMI blacklist. Required by PNP
939 bool "Old AMD GART IOMMU support"
943 depends on X86_64 && PCI && AMD_NB
945 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
946 GART based hardware IOMMUs.
948 The GART supports full DMA access for devices with 32-bit access
949 limitations, on systems with more than 3 GB. This is usually needed
950 for USB, sound, many IDE/SATA chipsets and some other devices.
952 Newer systems typically have a modern AMD IOMMU, supported via
953 the CONFIG_AMD_IOMMU=y config option.
955 In normal configurations this driver is only active when needed:
956 there's more than 3 GB of memory and the system contains a
957 32-bit limited device.
961 config BOOT_VESA_SUPPORT
964 If true, at least one selected framebuffer driver can take advantage
965 of VESA video modes set at an early boot stage via the vga= parameter.
968 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
969 depends on X86_64 && SMP && DEBUG_KERNEL
970 select CPUMASK_OFFSTACK
972 Enable maximum number of CPUS and NUMA Nodes for this architecture.
976 # The maximum number of CPUs supported:
978 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
979 # and which can be configured interactively in the
980 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
982 # The ranges are different on 32-bit and 64-bit kernels, depending on
983 # hardware capabilities and scalability features of the kernel.
985 # ( If MAXSMP is enabled we just use the highest possible value and disable
986 # interactive configuration. )
989 config NR_CPUS_RANGE_BEGIN
991 default NR_CPUS_RANGE_END if MAXSMP
995 config NR_CPUS_RANGE_END
998 default 64 if SMP && X86_BIGSMP
999 default 8 if SMP && !X86_BIGSMP
1002 config NR_CPUS_RANGE_END
1005 default 8192 if SMP && CPUMASK_OFFSTACK
1006 default 512 if SMP && !CPUMASK_OFFSTACK
1009 config NR_CPUS_DEFAULT
1012 default 32 if X86_BIGSMP
1016 config NR_CPUS_DEFAULT
1019 default 8192 if MAXSMP
1024 int "Maximum number of CPUs" if SMP && !MAXSMP
1025 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1026 default NR_CPUS_DEFAULT
1028 This allows you to specify the maximum number of CPUs which this
1029 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1030 supported value is 8192, otherwise the maximum value is 512. The
1031 minimum value which makes sense is 2.
1033 This is purely to save memory: each supported CPU adds about 8KB
1034 to the kernel image.
1036 config SCHED_CLUSTER
1037 bool "Cluster scheduler support"
1041 Cluster scheduler support improves the CPU scheduler's decision
1042 making when dealing with machines that have clusters of CPUs.
1043 Cluster usually means a couple of CPUs which are placed closely
1044 by sharing mid-level caches, last-level cache tags or internal
1052 prompt "Multi-core scheduler support"
1055 Multi-core scheduler support improves the CPU scheduler's decision
1056 making when dealing with multi-core CPU chips at a cost of slightly
1057 increased overhead in some places. If unsure say N here.
1059 config SCHED_MC_PRIO
1060 bool "CPU core priorities scheduler support"
1061 depends on SCHED_MC && CPU_SUP_INTEL
1062 select X86_INTEL_PSTATE
1066 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1067 core ordering determined at manufacturing time, which allows
1068 certain cores to reach higher turbo frequencies (when running
1069 single threaded workloads) than others.
1071 Enabling this kernel feature teaches the scheduler about
1072 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1073 scheduler's CPU selection logic accordingly, so that higher
1074 overall system performance can be achieved.
1076 This feature will have no effect on CPUs without this feature.
1078 If unsure say Y here.
1082 depends on !SMP && X86_LOCAL_APIC
1085 bool "Local APIC support on uniprocessors" if !PCI_MSI
1087 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1089 A local APIC (Advanced Programmable Interrupt Controller) is an
1090 integrated interrupt controller in the CPU. If you have a single-CPU
1091 system which has a processor with a local APIC, you can say Y here to
1092 enable and use it. If you say Y here even though your machine doesn't
1093 have a local APIC, then the kernel will still run with no slowdown at
1094 all. The local APIC supports CPU-generated self-interrupts (timer,
1095 performance counters), and the NMI watchdog which detects hard
1098 config X86_UP_IOAPIC
1099 bool "IO-APIC support on uniprocessors"
1100 depends on X86_UP_APIC
1102 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1103 SMP-capable replacement for PC-style interrupt controllers. Most
1104 SMP systems and many recent uniprocessor systems have one.
1106 If you have a single-CPU system with an IO-APIC, you can say Y here
1107 to use it. If you say Y here even though your machine doesn't have
1108 an IO-APIC, then the kernel will still run with no slowdown at all.
1110 config X86_LOCAL_APIC
1112 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1113 select IRQ_DOMAIN_HIERARCHY
1117 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1119 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1120 bool "Reroute for broken boot IRQs"
1121 depends on X86_IO_APIC
1123 This option enables a workaround that fixes a source of
1124 spurious interrupts. This is recommended when threaded
1125 interrupt handling is used on systems where the generation of
1126 superfluous "boot interrupts" cannot be disabled.
1128 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1129 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1130 kernel does during interrupt handling). On chipsets where this
1131 boot IRQ generation cannot be disabled, this workaround keeps
1132 the original IRQ line masked so that only the equivalent "boot
1133 IRQ" is delivered to the CPUs. The workaround also tells the
1134 kernel to set up the IRQ handler on the boot IRQ line. In this
1135 way only one interrupt is delivered to the kernel. Otherwise
1136 the spurious second interrupt may cause the kernel to bring
1137 down (vital) interrupt lines.
1139 Only affects "broken" chipsets. Interrupt sharing may be
1140 increased on these systems.
1143 bool "Machine Check / overheating reporting"
1144 select GENERIC_ALLOCATOR
1147 Machine Check support allows the processor to notify the
1148 kernel if it detects a problem (e.g. overheating, data corruption).
1149 The action the kernel takes depends on the severity of the problem,
1150 ranging from warning messages to halting the machine.
1152 config X86_MCELOG_LEGACY
1153 bool "Support for deprecated /dev/mcelog character device"
1156 Enable support for /dev/mcelog which is needed by the old mcelog
1157 userspace logging daemon. Consider switching to the new generation
1160 config X86_MCE_INTEL
1162 prompt "Intel MCE features"
1163 depends on X86_MCE && X86_LOCAL_APIC
1165 Additional support for intel specific MCE features such as
1166 the thermal monitor.
1170 prompt "AMD MCE features"
1171 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1173 Additional support for AMD specific MCE features such as
1174 the DRAM Error Threshold.
1176 config X86_ANCIENT_MCE
1177 bool "Support for old Pentium 5 / WinChip machine checks"
1178 depends on X86_32 && X86_MCE
1180 Include support for machine check handling on old Pentium 5 or WinChip
1181 systems. These typically need to be enabled explicitly on the command
1184 config X86_MCE_THRESHOLD
1185 depends on X86_MCE_AMD || X86_MCE_INTEL
1188 config X86_MCE_INJECT
1189 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1190 tristate "Machine check injector support"
1192 Provide support for injecting machine checks for testing purposes.
1193 If you don't know what a machine check is and you don't do kernel
1194 QA it is safe to say n.
1196 source "arch/x86/events/Kconfig"
1198 config X86_LEGACY_VM86
1199 bool "Legacy VM86 support"
1202 This option allows user programs to put the CPU into V8086
1203 mode, which is an 80286-era approximation of 16-bit real mode.
1205 Some very old versions of X and/or vbetool require this option
1206 for user mode setting. Similarly, DOSEMU will use it if
1207 available to accelerate real mode DOS programs. However, any
1208 recent version of DOSEMU, X, or vbetool should be fully
1209 functional even without kernel VM86 support, as they will all
1210 fall back to software emulation. Nevertheless, if you are using
1211 a 16-bit DOS program where 16-bit performance matters, vm86
1212 mode might be faster than emulation and you might want to
1215 Note that any app that works on a 64-bit kernel is unlikely to
1216 need this option, as 64-bit kernels don't, and can't, support
1217 V8086 mode. This option is also unrelated to 16-bit protected
1218 mode and is not needed to run most 16-bit programs under Wine.
1220 Enabling this option increases the complexity of the kernel
1221 and slows down exception handling a tiny bit.
1223 If unsure, say N here.
1227 default X86_LEGACY_VM86
1230 bool "Enable support for 16-bit segments" if EXPERT
1232 depends on MODIFY_LDT_SYSCALL
1234 This option is required by programs like Wine to run 16-bit
1235 protected mode legacy code on x86 processors. Disabling
1236 this option saves about 300 bytes on i386, or around 6K text
1237 plus 16K runtime memory on x86-64,
1241 depends on X86_16BIT && X86_32
1245 depends on X86_16BIT && X86_64
1247 config X86_VSYSCALL_EMULATION
1248 bool "Enable vsyscall emulation" if EXPERT
1252 This enables emulation of the legacy vsyscall page. Disabling
1253 it is roughly equivalent to booting with vsyscall=none, except
1254 that it will also disable the helpful warning if a program
1255 tries to use a vsyscall. With this option set to N, offending
1256 programs will just segfault, citing addresses of the form
1259 This option is required by many programs built before 2013, and
1260 care should be used even with newer programs if set to N.
1262 Disabling this option saves about 7K of kernel size and
1263 possibly 4K of additional runtime pagetable memory.
1265 config X86_IOPL_IOPERM
1266 bool "IOPERM and IOPL Emulation"
1269 This enables the ioperm() and iopl() syscalls which are necessary
1270 for legacy applications.
1272 Legacy IOPL support is an overbroad mechanism which allows user
1273 space aside of accessing all 65536 I/O ports also to disable
1274 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1275 capabilities and permission from potentially active security
1278 The emulation restricts the functionality of the syscall to
1279 only allowing the full range I/O port access, but prevents the
1280 ability to disable interrupts from user space which would be
1281 granted if the hardware IOPL mechanism would be used.
1284 tristate "Toshiba Laptop support"
1287 This adds a driver to safely access the System Management Mode of
1288 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1289 not work on models with a Phoenix BIOS. The System Management Mode
1290 is used to set the BIOS and power saving options on Toshiba portables.
1292 For information on utilities to make use of this driver see the
1293 Toshiba Linux utilities web site at:
1294 <http://www.buzzard.org.uk/toshiba/>.
1296 Say Y if you intend to run this kernel on a Toshiba portable.
1299 config X86_REBOOTFIXUPS
1300 bool "Enable X86 board specific fixups for reboot"
1303 This enables chipset and/or board specific fixups to be done
1304 in order to get reboot to work correctly. This is only needed on
1305 some combinations of hardware and BIOS. The symptom, for which
1306 this config is intended, is when reboot ends with a stalled/hung
1309 Currently, the only fixup is for the Geode machines using
1310 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1312 Say Y if you want to enable the fixup. Currently, it's safe to
1313 enable this option even if you don't need it.
1317 bool "CPU microcode loading support"
1319 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1321 If you say Y here, you will be able to update the microcode on
1322 Intel and AMD processors. The Intel support is for the IA32 family,
1323 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1324 AMD support is for families 0x10 and later. You will obviously need
1325 the actual microcode binary data itself which is not shipped with
1328 The preferred method to load microcode from a detached initrd is described
1329 in Documentation/arch/x86/microcode.rst. For that you need to enable
1330 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1331 initrd for microcode blobs.
1333 In addition, you can build the microcode into the kernel. For that you
1334 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1337 config MICROCODE_INTEL
1338 bool "Intel microcode loading support"
1339 depends on CPU_SUP_INTEL && MICROCODE
1342 This options enables microcode patch loading support for Intel
1345 For the current Intel microcode data package go to
1346 <https://downloadcenter.intel.com> and search for
1347 'Linux Processor Microcode Data File'.
1349 config MICROCODE_AMD
1350 bool "AMD microcode loading support"
1351 depends on CPU_SUP_AMD && MICROCODE
1353 If you select this option, microcode patch loading support for AMD
1354 processors will be enabled.
1356 config MICROCODE_LATE_LOADING
1357 bool "Late microcode loading (DANGEROUS)"
1359 depends on MICROCODE
1361 Loading microcode late, when the system is up and executing instructions
1362 is a tricky business and should be avoided if possible. Just the sequence
1363 of synchronizing all cores and SMT threads is one fragile dance which does
1364 not guarantee that cores might not softlock after the loading. Therefore,
1365 use this at your own risk. Late loading taints the kernel too.
1368 tristate "/dev/cpu/*/msr - Model-specific register support"
1370 This device gives privileged processes access to the x86
1371 Model-Specific Registers (MSRs). It is a character device with
1372 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1373 MSR accesses are directed to a specific CPU on multi-processor
1377 tristate "/dev/cpu/*/cpuid - CPU information support"
1379 This device gives processes access to the x86 CPUID instruction to
1380 be executed on a specific processor. It is a character device
1381 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1385 prompt "High Memory Support"
1392 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1393 However, the address space of 32-bit x86 processors is only 4
1394 Gigabytes large. That means that, if you have a large amount of
1395 physical memory, not all of it can be "permanently mapped" by the
1396 kernel. The physical memory that's not permanently mapped is called
1399 If you are compiling a kernel which will never run on a machine with
1400 more than 1 Gigabyte total physical RAM, answer "off" here (default
1401 choice and suitable for most users). This will result in a "3GB/1GB"
1402 split: 3GB are mapped so that each process sees a 3GB virtual memory
1403 space and the remaining part of the 4GB virtual memory space is used
1404 by the kernel to permanently map as much physical memory as
1407 If the machine has between 1 and 4 Gigabytes physical RAM, then
1410 If more than 4 Gigabytes is used then answer "64GB" here. This
1411 selection turns Intel PAE (Physical Address Extension) mode on.
1412 PAE implements 3-level paging on IA32 processors. PAE is fully
1413 supported by Linux, PAE mode is implemented on all recent Intel
1414 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1415 then the kernel will not boot on CPUs that don't support PAE!
1417 The actual amount of total physical memory will either be
1418 auto detected or can be forced by using a kernel command line option
1419 such as "mem=256M". (Try "man bootparam" or see the documentation of
1420 your boot loader (lilo or loadlin) about how to pass options to the
1421 kernel at boot time.)
1423 If unsure, say "off".
1428 Select this if you have a 32-bit processor and between 1 and 4
1429 gigabytes of physical RAM.
1433 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1436 Select this if you have a 32-bit processor and more than 4
1437 gigabytes of physical RAM.
1442 prompt "Memory split" if EXPERT
1446 Select the desired split between kernel and user memory.
1448 If the address range available to the kernel is less than the
1449 physical memory installed, the remaining memory will be available
1450 as "high memory". Accessing high memory is a little more costly
1451 than low memory, as it needs to be mapped into the kernel first.
1452 Note that increasing the kernel address space limits the range
1453 available to user programs, making the address space there
1454 tighter. Selecting anything other than the default 3G/1G split
1455 will also likely make your kernel incompatible with binary-only
1458 If you are not absolutely sure what you are doing, leave this
1462 bool "3G/1G user/kernel split"
1463 config VMSPLIT_3G_OPT
1465 bool "3G/1G user/kernel split (for full 1G low memory)"
1467 bool "2G/2G user/kernel split"
1468 config VMSPLIT_2G_OPT
1470 bool "2G/2G user/kernel split (for full 2G low memory)"
1472 bool "1G/3G user/kernel split"
1477 default 0xB0000000 if VMSPLIT_3G_OPT
1478 default 0x80000000 if VMSPLIT_2G
1479 default 0x78000000 if VMSPLIT_2G_OPT
1480 default 0x40000000 if VMSPLIT_1G
1486 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1489 bool "PAE (Physical Address Extension) Support"
1490 depends on X86_32 && !HIGHMEM4G
1491 select PHYS_ADDR_T_64BIT
1494 PAE is required for NX support, and furthermore enables
1495 larger swapspace support for non-overcommit purposes. It
1496 has the cost of more pagetable lookup overhead, and also
1497 consumes more pagetable space per process.
1500 bool "Enable 5-level page tables support"
1502 select DYNAMIC_MEMORY_LAYOUT
1503 select SPARSEMEM_VMEMMAP
1506 5-level paging enables access to larger address space:
1507 up to 128 PiB of virtual address space and 4 PiB of
1508 physical address space.
1510 It will be supported by future Intel CPUs.
1512 A kernel with the option enabled can be booted on machines that
1513 support 4- or 5-level paging.
1515 See Documentation/arch/x86/x86_64/5level-paging.rst for more
1520 config X86_DIRECT_GBPAGES
1524 Certain kernel features effectively disable kernel
1525 linear 1 GB mappings (even if the CPU otherwise
1526 supports them), so don't confuse the user by printing
1527 that we have them enabled.
1529 config X86_CPA_STATISTICS
1530 bool "Enable statistic for Change Page Attribute"
1533 Expose statistics about the Change Page Attribute mechanism, which
1534 helps to determine the effectiveness of preserving large and huge
1535 page mappings when mapping protections are changed.
1537 config X86_MEM_ENCRYPT
1538 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1539 select DYNAMIC_PHYSICAL_MASK
1542 config AMD_MEM_ENCRYPT
1543 bool "AMD Secure Memory Encryption (SME) support"
1544 depends on X86_64 && CPU_SUP_AMD
1545 select DMA_COHERENT_POOL
1546 select ARCH_USE_MEMREMAP_PROT
1547 select INSTRUCTION_DECODER
1548 select ARCH_HAS_CC_PLATFORM
1549 select X86_MEM_ENCRYPT
1551 Say yes to enable support for the encryption of system memory.
1552 This requires an AMD processor that supports Secure Memory
1555 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1556 bool "Activate AMD Secure Memory Encryption (SME) by default"
1557 depends on AMD_MEM_ENCRYPT
1559 Say yes to have system memory encrypted by default if running on
1560 an AMD processor that supports Secure Memory Encryption (SME).
1562 If set to Y, then the encryption of system memory can be
1563 deactivated with the mem_encrypt=off command line option.
1565 If set to N, then the encryption of system memory can be
1566 activated with the mem_encrypt=on command line option.
1568 # Common NUMA Features
1570 bool "NUMA Memory Allocation and Scheduler Support"
1572 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1573 default y if X86_BIGSMP
1574 select USE_PERCPU_NUMA_NODE_ID
1576 Enable NUMA (Non-Uniform Memory Access) support.
1578 The kernel will try to allocate memory used by a CPU on the
1579 local memory controller of the CPU and add some more
1580 NUMA awareness to the kernel.
1582 For 64-bit this is recommended if the system is Intel Core i7
1583 (or later), AMD Opteron, or EM64T NUMA.
1585 For 32-bit this is only needed if you boot a 32-bit
1586 kernel on a 64-bit NUMA platform.
1588 Otherwise, you should say N.
1592 prompt "Old style AMD Opteron NUMA detection"
1593 depends on X86_64 && NUMA && PCI
1595 Enable AMD NUMA node topology detection. You should say Y here if
1596 you have a multi processor AMD system. This uses an old method to
1597 read the NUMA configuration directly from the builtin Northbridge
1598 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1599 which also takes priority if both are compiled in.
1601 config X86_64_ACPI_NUMA
1603 prompt "ACPI NUMA detection"
1604 depends on X86_64 && NUMA && ACPI && PCI
1607 Enable ACPI SRAT based node topology detection.
1610 bool "NUMA emulation"
1613 Enable NUMA emulation. A flat machine will be split
1614 into virtual nodes when booted with "numa=fake=N", where N is the
1615 number of nodes. This is only useful for debugging.
1618 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1620 default "10" if MAXSMP
1621 default "6" if X86_64
1625 Specify the maximum number of NUMA Nodes available on the target
1626 system. Increases memory reserved to accommodate various tables.
1628 config ARCH_FLATMEM_ENABLE
1630 depends on X86_32 && !NUMA
1632 config ARCH_SPARSEMEM_ENABLE
1634 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1635 select SPARSEMEM_STATIC if X86_32
1636 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1638 config ARCH_SPARSEMEM_DEFAULT
1639 def_bool X86_64 || (NUMA && X86_32)
1641 config ARCH_SELECT_MEMORY_MODEL
1643 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1645 config ARCH_MEMORY_PROBE
1646 bool "Enable sysfs memory/probe interface"
1647 depends on MEMORY_HOTPLUG
1649 This option enables a sysfs memory/probe interface for testing.
1650 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1651 If you are unsure how to answer this question, answer N.
1653 config ARCH_PROC_KCORE_TEXT
1655 depends on X86_64 && PROC_KCORE
1657 config ILLEGAL_POINTER_VALUE
1660 default 0xdead000000000000 if X86_64
1662 config X86_PMEM_LEGACY_DEVICE
1665 config X86_PMEM_LEGACY
1666 tristate "Support non-standard NVDIMMs and ADR protected memory"
1667 depends on PHYS_ADDR_T_64BIT
1669 select X86_PMEM_LEGACY_DEVICE
1670 select NUMA_KEEP_MEMINFO if NUMA
1673 Treat memory marked using the non-standard e820 type of 12 as used
1674 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1675 The kernel will offer these regions to the 'pmem' driver so
1676 they can be used for persistent storage.
1681 bool "Allocate 3rd-level pagetables from highmem"
1684 The VM uses one page table entry for each page of physical memory.
1685 For systems with a lot of RAM, this can be wasteful of precious
1686 low memory. Setting this option will put user-space page table
1687 entries in high memory.
1689 config X86_CHECK_BIOS_CORRUPTION
1690 bool "Check for low memory corruption"
1692 Periodically check for memory corruption in low memory, which
1693 is suspected to be caused by BIOS. Even when enabled in the
1694 configuration, it is disabled at runtime. Enable it by
1695 setting "memory_corruption_check=1" on the kernel command
1696 line. By default it scans the low 64k of memory every 60
1697 seconds; see the memory_corruption_check_size and
1698 memory_corruption_check_period parameters in
1699 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1701 When enabled with the default parameters, this option has
1702 almost no overhead, as it reserves a relatively small amount
1703 of memory and scans it infrequently. It both detects corruption
1704 and prevents it from affecting the running system.
1706 It is, however, intended as a diagnostic tool; if repeatable
1707 BIOS-originated corruption always affects the same memory,
1708 you can use memmap= to prevent the kernel from using that
1711 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1712 bool "Set the default setting of memory_corruption_check"
1713 depends on X86_CHECK_BIOS_CORRUPTION
1716 Set whether the default state of memory_corruption_check is
1719 config MATH_EMULATION
1721 depends on MODIFY_LDT_SYSCALL
1722 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1724 Linux can emulate a math coprocessor (used for floating point
1725 operations) if you don't have one. 486DX and Pentium processors have
1726 a math coprocessor built in, 486SX and 386 do not, unless you added
1727 a 487DX or 387, respectively. (The messages during boot time can
1728 give you some hints here ["man dmesg"].) Everyone needs either a
1729 coprocessor or this emulation.
1731 If you don't have a math coprocessor, you need to say Y here; if you
1732 say Y here even though you have a coprocessor, the coprocessor will
1733 be used nevertheless. (This behavior can be changed with the kernel
1734 command line option "no387", which comes handy if your coprocessor
1735 is broken. Try "man bootparam" or see the documentation of your boot
1736 loader (lilo or loadlin) about how to pass options to the kernel at
1737 boot time.) This means that it is a good idea to say Y here if you
1738 intend to use this kernel on different machines.
1740 More information about the internals of the Linux math coprocessor
1741 emulation can be found in <file:arch/x86/math-emu/README>.
1743 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1744 kernel, it won't hurt.
1748 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1750 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1751 the Memory Type Range Registers (MTRRs) may be used to control
1752 processor access to memory ranges. This is most useful if you have
1753 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1754 allows bus write transfers to be combined into a larger transfer
1755 before bursting over the PCI/AGP bus. This can increase performance
1756 of image write operations 2.5 times or more. Saying Y here creates a
1757 /proc/mtrr file which may be used to manipulate your processor's
1758 MTRRs. Typically the X server should use this.
1760 This code has a reasonably generic interface so that similar
1761 control registers on other processors can be easily supported
1764 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1765 Registers (ARRs) which provide a similar functionality to MTRRs. For
1766 these, the ARRs are used to emulate the MTRRs.
1767 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1768 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1769 write-combining. All of these processors are supported by this code
1770 and it makes sense to say Y here if you have one of them.
1772 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1773 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1774 can lead to all sorts of problems, so it's good to say Y here.
1776 You can safely say Y even if your machine doesn't have MTRRs, you'll
1777 just add about 9 KB to your kernel.
1779 See <file:Documentation/arch/x86/mtrr.rst> for more information.
1781 config MTRR_SANITIZER
1783 prompt "MTRR cleanup support"
1786 Convert MTRR layout from continuous to discrete, so X drivers can
1787 add writeback entries.
1789 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1790 The largest mtrr entry size for a continuous block can be set with
1795 config MTRR_SANITIZER_ENABLE_DEFAULT
1796 int "MTRR cleanup enable value (0-1)"
1799 depends on MTRR_SANITIZER
1801 Enable mtrr cleanup default value
1803 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1804 int "MTRR cleanup spare reg num (0-7)"
1807 depends on MTRR_SANITIZER
1809 mtrr cleanup spare entries default, it can be changed via
1810 mtrr_spare_reg_nr=N on the kernel command line.
1814 prompt "x86 PAT support" if EXPERT
1817 Use PAT attributes to setup page level cache control.
1819 PATs are the modern equivalents of MTRRs and are much more
1820 flexible than MTRRs.
1822 Say N here if you see bootup problems (boot crash, boot hang,
1823 spontaneous reboots) or a non-working video driver.
1827 config ARCH_USES_PG_UNCACHED
1833 prompt "User Mode Instruction Prevention" if EXPERT
1835 User Mode Instruction Prevention (UMIP) is a security feature in
1836 some x86 processors. If enabled, a general protection fault is
1837 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1838 executed in user mode. These instructions unnecessarily expose
1839 information about the hardware state.
1841 The vast majority of applications do not use these instructions.
1842 For the very few that do, software emulation is provided in
1843 specific cases in protected and virtual-8086 modes. Emulated
1847 # GCC >= 9 and binutils >= 2.29
1848 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1850 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1851 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1852 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1853 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1856 config X86_KERNEL_IBT
1857 prompt "Indirect Branch Tracking"
1859 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1860 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1861 depends on !LD_IS_LLD || LLD_VERSION >= 140000
1864 Build the kernel with support for Indirect Branch Tracking, a
1865 hardware support course-grain forward-edge Control Flow Integrity
1866 protection. It enforces that all indirect calls must land on
1867 an ENDBR instruction, as such, the compiler will instrument the
1868 code with them to make this happen.
1870 In addition to building the kernel with IBT, seal all functions that
1871 are not indirect call targets, avoiding them ever becoming one.
1873 This requires LTO like objtool runs and will slow down the build. It
1874 does significantly reduce the number of ENDBR instructions in the
1877 config X86_INTEL_MEMORY_PROTECTION_KEYS
1878 prompt "Memory Protection Keys"
1880 # Note: only available in 64-bit mode
1881 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1882 select ARCH_USES_HIGH_VMA_FLAGS
1883 select ARCH_HAS_PKEYS
1885 Memory Protection Keys provides a mechanism for enforcing
1886 page-based protections, but without requiring modification of the
1887 page tables when an application changes protection domains.
1889 For details, see Documentation/core-api/protection-keys.rst
1894 prompt "TSX enable mode"
1895 depends on CPU_SUP_INTEL
1896 default X86_INTEL_TSX_MODE_OFF
1898 Intel's TSX (Transactional Synchronization Extensions) feature
1899 allows to optimize locking protocols through lock elision which
1900 can lead to a noticeable performance boost.
1902 On the other hand it has been shown that TSX can be exploited
1903 to form side channel attacks (e.g. TAA) and chances are there
1904 will be more of those attacks discovered in the future.
1906 Therefore TSX is not enabled by default (aka tsx=off). An admin
1907 might override this decision by tsx=on the command line parameter.
1908 Even with TSX enabled, the kernel will attempt to enable the best
1909 possible TAA mitigation setting depending on the microcode available
1910 for the particular machine.
1912 This option allows to set the default tsx mode between tsx=on, =off
1913 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1916 Say off if not sure, auto if TSX is in use but it should be used on safe
1917 platforms or on if TSX is in use and the security aspect of tsx is not
1920 config X86_INTEL_TSX_MODE_OFF
1923 TSX is disabled if possible - equals to tsx=off command line parameter.
1925 config X86_INTEL_TSX_MODE_ON
1928 TSX is always enabled on TSX capable HW - equals the tsx=on command
1931 config X86_INTEL_TSX_MODE_AUTO
1934 TSX is enabled on TSX capable HW that is believed to be safe against
1935 side channel attacks- equals the tsx=auto command line parameter.
1939 bool "Software Guard eXtensions (SGX)"
1940 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1942 depends on CRYPTO_SHA256=y
1944 select NUMA_KEEP_MEMINFO if NUMA
1947 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1948 that can be used by applications to set aside private regions of code
1949 and data, referred to as enclaves. An enclave's private memory can
1950 only be accessed by code running within the enclave. Accesses from
1951 outside the enclave, including other enclaves, are disallowed by
1957 bool "EFI runtime service support"
1960 select EFI_RUNTIME_WRAPPERS
1961 select ARCH_USE_MEMREMAP_PROT
1963 This enables the kernel to use EFI runtime services that are
1964 available (such as the EFI variable services).
1966 This option is only useful on systems that have EFI firmware.
1967 In addition, you should use the latest ELILO loader available
1968 at <http://elilo.sourceforge.net> in order to take advantage
1969 of EFI runtime services. However, even with this option, the
1970 resultant kernel should continue to boot on existing non-EFI
1974 bool "EFI stub support"
1978 This kernel feature allows a bzImage to be loaded directly
1979 by EFI firmware without the use of a bootloader.
1981 See Documentation/admin-guide/efi-stub.rst for more information.
1983 config EFI_HANDOVER_PROTOCOL
1984 bool "EFI handover protocol (DEPRECATED)"
1988 Select this in order to include support for the deprecated EFI
1989 handover protocol, which defines alternative entry points into the
1990 EFI stub. This is a practice that has no basis in the UEFI
1991 specification, and requires a priori knowledge on the part of the
1992 bootloader about Linux/x86 specific ways of passing the command line
1993 and initrd, and where in memory those assets may be loaded.
1995 If in doubt, say Y. Even though the corresponding support is not
1996 present in upstream GRUB or other bootloaders, most distros build
1997 GRUB with numerous downstream patches applied, and may rely on the
1998 handover protocol as as result.
2001 bool "EFI mixed-mode support"
2002 depends on EFI_STUB && X86_64
2004 Enabling this feature allows a 64-bit kernel to be booted
2005 on a 32-bit firmware, provided that your CPU supports 64-bit
2008 Note that it is not possible to boot a mixed-mode enabled
2009 kernel via the EFI boot stub - a bootloader that supports
2010 the EFI handover protocol must be used.
2014 config EFI_FAKE_MEMMAP
2015 bool "Enable EFI fake memory map"
2018 Saying Y here will enable "efi_fake_mem" boot option. By specifying
2019 this parameter, you can add arbitrary attribute to specific memory
2020 range by updating original (firmware provided) EFI memmap. This is
2021 useful for debugging of EFI memmap related feature, e.g., Address
2022 Range Mirroring feature.
2024 config EFI_MAX_FAKE_MEM
2025 int "maximum allowable number of ranges in efi_fake_mem boot option"
2026 depends on EFI_FAKE_MEMMAP
2030 Maximum allowable number of ranges in efi_fake_mem boot option.
2031 Ranges can be set up to this value using comma-separated list.
2032 The default value is 8.
2034 config EFI_RUNTIME_MAP
2035 bool "Export EFI runtime maps to sysfs" if EXPERT
2039 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2040 That memory map is required by the 2nd kernel to set up EFI virtual
2041 mappings after kexec, but can also be used for debugging purposes.
2043 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2045 source "kernel/Kconfig.hz"
2048 bool "kexec system call"
2051 kexec is a system call that implements the ability to shutdown your
2052 current kernel, and to start another kernel. It is like a reboot
2053 but it is independent of the system firmware. And like a reboot
2054 you can start any kernel with it, not just Linux.
2056 The name comes from the similarity to the exec system call.
2058 It is an ongoing process to be certain the hardware in a machine
2059 is properly shutdown, so do not be surprised if this code does not
2060 initially work for you. As of this writing the exact hardware
2061 interface is strongly in flux, so no good recommendation can be
2065 bool "kexec file based system call"
2067 select HAVE_IMA_KEXEC if IMA
2070 depends on CRYPTO_SHA256=y
2072 This is new version of kexec system call. This system call is
2073 file based and takes file descriptors as system call argument
2074 for kernel and initramfs as opposed to list of segments as
2075 accepted by previous system call.
2077 config ARCH_HAS_KEXEC_PURGATORY
2081 bool "Verify kernel signature during kexec_file_load() syscall"
2082 depends on KEXEC_FILE
2085 This option makes the kexec_file_load() syscall check for a valid
2086 signature of the kernel image. The image can still be loaded without
2087 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2088 there's a signature that we can check, then it must be valid.
2090 In addition to this option, you need to enable signature
2091 verification for the corresponding kernel image type being
2092 loaded in order for this to work.
2094 config KEXEC_SIG_FORCE
2095 bool "Require a valid signature in kexec_file_load() syscall"
2096 depends on KEXEC_SIG
2098 This option makes kernel signature verification mandatory for
2099 the kexec_file_load() syscall.
2101 config KEXEC_BZIMAGE_VERIFY_SIG
2102 bool "Enable bzImage signature verification support"
2103 depends on KEXEC_SIG
2104 depends on SIGNED_PE_FILE_VERIFICATION
2105 select SYSTEM_TRUSTED_KEYRING
2107 Enable bzImage signature verification support.
2110 bool "kernel crash dumps"
2111 depends on X86_64 || (X86_32 && HIGHMEM)
2113 Generate crash dump after being started by kexec.
2114 This should be normally only set in special crash dump kernels
2115 which are loaded in the main kernel with kexec-tools into
2116 a specially reserved region and then later executed after
2117 a crash by kdump/kexec. The crash dump kernel must be compiled
2118 to a memory address not used by the main kernel or BIOS using
2119 PHYSICAL_START, or it must be built as a relocatable image
2120 (CONFIG_RELOCATABLE=y).
2121 For more details see Documentation/admin-guide/kdump/kdump.rst
2125 depends on KEXEC && HIBERNATION
2127 Jump between original kernel and kexeced kernel and invoke
2128 code in physical address mode via KEXEC
2130 config PHYSICAL_START
2131 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2134 This gives the physical address where the kernel is loaded.
2136 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2137 bzImage will decompress itself to above physical address and
2138 run from there. Otherwise, bzImage will run from the address where
2139 it has been loaded by the boot loader and will ignore above physical
2142 In normal kdump cases one does not have to set/change this option
2143 as now bzImage can be compiled as a completely relocatable image
2144 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2145 address. This option is mainly useful for the folks who don't want
2146 to use a bzImage for capturing the crash dump and want to use a
2147 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2148 to be specifically compiled to run from a specific memory area
2149 (normally a reserved region) and this option comes handy.
2151 So if you are using bzImage for capturing the crash dump,
2152 leave the value here unchanged to 0x1000000 and set
2153 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2154 for capturing the crash dump change this value to start of
2155 the reserved region. In other words, it can be set based on
2156 the "X" value as specified in the "crashkernel=YM@XM"
2157 command line boot parameter passed to the panic-ed
2158 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2159 for more details about crash dumps.
2161 Usage of bzImage for capturing the crash dump is recommended as
2162 one does not have to build two kernels. Same kernel can be used
2163 as production kernel and capture kernel. Above option should have
2164 gone away after relocatable bzImage support is introduced. But it
2165 is present because there are users out there who continue to use
2166 vmlinux for dump capture. This option should go away down the
2169 Don't change this unless you know what you are doing.
2172 bool "Build a relocatable kernel"
2175 This builds a kernel image that retains relocation information
2176 so it can be loaded someplace besides the default 1MB.
2177 The relocations tend to make the kernel binary about 10% larger,
2178 but are discarded at runtime.
2180 One use is for the kexec on panic case where the recovery kernel
2181 must live at a different physical address than the primary
2184 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2185 it has been loaded at and the compile time physical address
2186 (CONFIG_PHYSICAL_START) is used as the minimum location.
2188 config RANDOMIZE_BASE
2189 bool "Randomize the address of the kernel image (KASLR)"
2190 depends on RELOCATABLE
2193 In support of Kernel Address Space Layout Randomization (KASLR),
2194 this randomizes the physical address at which the kernel image
2195 is decompressed and the virtual address where the kernel
2196 image is mapped, as a security feature that deters exploit
2197 attempts relying on knowledge of the location of kernel
2200 On 64-bit, the kernel physical and virtual addresses are
2201 randomized separately. The physical address will be anywhere
2202 between 16MB and the top of physical memory (up to 64TB). The
2203 virtual address will be randomized from 16MB up to 1GB (9 bits
2204 of entropy). Note that this also reduces the memory space
2205 available to kernel modules from 1.5GB to 1GB.
2207 On 32-bit, the kernel physical and virtual addresses are
2208 randomized together. They will be randomized from 16MB up to
2209 512MB (8 bits of entropy).
2211 Entropy is generated using the RDRAND instruction if it is
2212 supported. If RDTSC is supported, its value is mixed into
2213 the entropy pool as well. If neither RDRAND nor RDTSC are
2214 supported, then entropy is read from the i8254 timer. The
2215 usable entropy is limited by the kernel being built using
2216 2GB addressing, and that PHYSICAL_ALIGN must be at a
2217 minimum of 2MB. As a result, only 10 bits of entropy are
2218 theoretically possible, but the implementations are further
2219 limited due to memory layouts.
2223 # Relocation on x86 needs some additional build support
2224 config X86_NEED_RELOCS
2226 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2228 config PHYSICAL_ALIGN
2229 hex "Alignment value to which kernel should be aligned"
2231 range 0x2000 0x1000000 if X86_32
2232 range 0x200000 0x1000000 if X86_64
2234 This value puts the alignment restrictions on physical address
2235 where kernel is loaded and run from. Kernel is compiled for an
2236 address which meets above alignment restriction.
2238 If bootloader loads the kernel at a non-aligned address and
2239 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2240 address aligned to above value and run from there.
2242 If bootloader loads the kernel at a non-aligned address and
2243 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2244 load address and decompress itself to the address it has been
2245 compiled for and run from there. The address for which kernel is
2246 compiled already meets above alignment restrictions. Hence the
2247 end result is that kernel runs from a physical address meeting
2248 above alignment restrictions.
2250 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2251 this value must be a multiple of 0x200000.
2253 Don't change this unless you know what you are doing.
2255 config DYNAMIC_MEMORY_LAYOUT
2258 This option makes base addresses of vmalloc and vmemmap as well as
2259 __PAGE_OFFSET movable during boot.
2261 config RANDOMIZE_MEMORY
2262 bool "Randomize the kernel memory sections"
2264 depends on RANDOMIZE_BASE
2265 select DYNAMIC_MEMORY_LAYOUT
2266 default RANDOMIZE_BASE
2268 Randomizes the base virtual address of kernel memory sections
2269 (physical memory mapping, vmalloc & vmemmap). This security feature
2270 makes exploits relying on predictable memory locations less reliable.
2272 The order of allocations remains unchanged. Entropy is generated in
2273 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2274 configuration have in average 30,000 different possible virtual
2275 addresses for each memory section.
2279 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2280 hex "Physical memory mapping padding" if EXPERT
2281 depends on RANDOMIZE_MEMORY
2282 default "0xa" if MEMORY_HOTPLUG
2284 range 0x1 0x40 if MEMORY_HOTPLUG
2287 Define the padding in terabytes added to the existing physical
2288 memory size during kernel memory randomization. It is useful
2289 for memory hotplug support but reduces the entropy available for
2290 address randomization.
2292 If unsure, leave at the default value.
2294 config ADDRESS_MASKING
2295 bool "Linear Address Masking support"
2298 Linear Address Masking (LAM) modifies the checking that is applied
2299 to 64-bit linear addresses, allowing software to use of the
2300 untranslated address bits for metadata.
2302 The capability can be used for efficient address sanitizers (ASAN)
2303 implementation and for optimizations in JITs.
2309 config BOOTPARAM_HOTPLUG_CPU0
2310 bool "Set default setting of cpu0_hotpluggable"
2311 depends on HOTPLUG_CPU
2313 Set whether default state of cpu0_hotpluggable is on or off.
2315 Say Y here to enable CPU0 hotplug by default. If this switch
2316 is turned on, there is no need to give cpu0_hotplug kernel
2317 parameter and the CPU0 hotplug feature is enabled by default.
2319 Please note: there are two known CPU0 dependencies if you want
2320 to enable the CPU0 hotplug feature either by this switch or by
2321 cpu0_hotplug kernel parameter.
2323 First, resume from hibernate or suspend always starts from CPU0.
2324 So hibernate and suspend are prevented if CPU0 is offline.
2326 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2327 offline if any interrupt can not migrate out of CPU0. There may
2328 be other CPU0 dependencies.
2330 Please make sure the dependencies are under your control before
2331 you enable this feature.
2333 Say N if you don't want to enable CPU0 hotplug feature by default.
2334 You still can enable the CPU0 hotplug feature at boot by kernel
2335 parameter cpu0_hotplug.
2337 config DEBUG_HOTPLUG_CPU0
2339 prompt "Debug CPU0 hotplug"
2340 depends on HOTPLUG_CPU
2342 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2343 soon as possible and boots up userspace with CPU0 offlined. User
2344 can online CPU0 back after boot time.
2346 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2347 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2348 compilation or giving cpu0_hotplug kernel parameter at boot.
2354 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2355 depends on COMPAT_32
2357 Certain buggy versions of glibc will crash if they are
2358 presented with a 32-bit vDSO that is not mapped at the address
2359 indicated in its segment table.
2361 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2362 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2363 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2364 the only released version with the bug, but OpenSUSE 9
2365 contains a buggy "glibc 2.3.2".
2367 The symptom of the bug is that everything crashes on startup, saying:
2368 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2370 Saying Y here changes the default value of the vdso32 boot
2371 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2372 This works around the glibc bug but hurts performance.
2374 If unsure, say N: if you are compiling your own kernel, you
2375 are unlikely to be using a buggy version of glibc.
2378 prompt "vsyscall table for legacy applications"
2380 default LEGACY_VSYSCALL_XONLY
2382 Legacy user code that does not know how to find the vDSO expects
2383 to be able to issue three syscalls by calling fixed addresses in
2384 kernel space. Since this location is not randomized with ASLR,
2385 it can be used to assist security vulnerability exploitation.
2387 This setting can be changed at boot time via the kernel command
2388 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2389 is deprecated and can only be enabled using the kernel command
2392 On a system with recent enough glibc (2.14 or newer) and no
2393 static binaries, you can say None without a performance penalty
2394 to improve security.
2396 If unsure, select "Emulate execution only".
2398 config LEGACY_VSYSCALL_XONLY
2399 bool "Emulate execution only"
2401 The kernel traps and emulates calls into the fixed vsyscall
2402 address mapping and does not allow reads. This
2403 configuration is recommended when userspace might use the
2404 legacy vsyscall area but support for legacy binary
2405 instrumentation of legacy code is not needed. It mitigates
2406 certain uses of the vsyscall area as an ASLR-bypassing
2409 config LEGACY_VSYSCALL_NONE
2412 There will be no vsyscall mapping at all. This will
2413 eliminate any risk of ASLR bypass due to the vsyscall
2414 fixed address mapping. Attempts to use the vsyscalls
2415 will be reported to dmesg, so that either old or
2416 malicious userspace programs can be identified.
2421 bool "Built-in kernel command line"
2423 Allow for specifying boot arguments to the kernel at
2424 build time. On some systems (e.g. embedded ones), it is
2425 necessary or convenient to provide some or all of the
2426 kernel boot arguments with the kernel itself (that is,
2427 to not rely on the boot loader to provide them.)
2429 To compile command line arguments into the kernel,
2430 set this option to 'Y', then fill in the
2431 boot arguments in CONFIG_CMDLINE.
2433 Systems with fully functional boot loaders (i.e. non-embedded)
2434 should leave this option set to 'N'.
2437 string "Built-in kernel command string"
2438 depends on CMDLINE_BOOL
2441 Enter arguments here that should be compiled into the kernel
2442 image and used at boot time. If the boot loader provides a
2443 command line at boot time, it is appended to this string to
2444 form the full kernel command line, when the system boots.
2446 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2447 change this behavior.
2449 In most cases, the command line (whether built-in or provided
2450 by the boot loader) should specify the device for the root
2453 config CMDLINE_OVERRIDE
2454 bool "Built-in command line overrides boot loader arguments"
2455 depends on CMDLINE_BOOL && CMDLINE != ""
2457 Set this option to 'Y' to have the kernel ignore the boot loader
2458 command line, and use ONLY the built-in command line.
2460 This is used to work around broken boot loaders. This should
2461 be set to 'N' under normal conditions.
2463 config MODIFY_LDT_SYSCALL
2464 bool "Enable the LDT (local descriptor table)" if EXPERT
2467 Linux can allow user programs to install a per-process x86
2468 Local Descriptor Table (LDT) using the modify_ldt(2) system
2469 call. This is required to run 16-bit or segmented code such as
2470 DOSEMU or some Wine programs. It is also used by some very old
2471 threading libraries.
2473 Enabling this feature adds a small amount of overhead to
2474 context switches and increases the low-level kernel attack
2475 surface. Disabling it removes the modify_ldt(2) system call.
2477 Saying 'N' here may make sense for embedded or server kernels.
2479 config STRICT_SIGALTSTACK_SIZE
2480 bool "Enforce strict size checking for sigaltstack"
2481 depends on DYNAMIC_SIGFRAME
2483 For historical reasons MINSIGSTKSZ is a constant which became
2484 already too small with AVX512 support. Add a mechanism to
2485 enforce strict checking of the sigaltstack size against the
2486 real size of the FPU frame. This option enables the check
2487 by default. It can also be controlled via the kernel command
2488 line option 'strict_sas_size' independent of this config
2489 switch. Enabling it might break existing applications which
2490 allocate a too small sigaltstack but 'work' because they
2491 never get a signal delivered.
2493 Say 'N' unless you want to really enforce this check.
2495 source "kernel/livepatch/Kconfig"
2500 def_bool $(cc-option,-mharden-sls=all)
2502 config CC_HAS_RETURN_THUNK
2503 def_bool $(cc-option,-mfunction-return=thunk-extern)
2505 config CC_HAS_ENTRY_PADDING
2506 def_bool $(cc-option,-fpatchable-function-entry=16,16)
2508 config FUNCTION_PADDING_CFI
2510 default 59 if FUNCTION_ALIGNMENT_64B
2511 default 27 if FUNCTION_ALIGNMENT_32B
2512 default 11 if FUNCTION_ALIGNMENT_16B
2513 default 3 if FUNCTION_ALIGNMENT_8B
2516 # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2517 # except Kconfig can't do arithmetic :/
2518 config FUNCTION_PADDING_BYTES
2520 default FUNCTION_PADDING_CFI if CFI_CLANG
2521 default FUNCTION_ALIGNMENT
2525 depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2526 select FUNCTION_ALIGNMENT_16B
2530 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
2533 config HAVE_CALL_THUNKS
2535 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
2541 config PREFIX_SYMBOLS
2543 depends on CALL_PADDING && !CFI_CLANG
2545 menuconfig SPECULATION_MITIGATIONS
2546 bool "Mitigations for speculative execution vulnerabilities"
2549 Say Y here to enable options which enable mitigations for
2550 speculative execution hardware vulnerabilities.
2552 If you say N, all mitigations will be disabled. You really
2553 should know what you are doing to say so.
2555 if SPECULATION_MITIGATIONS
2557 config PAGE_TABLE_ISOLATION
2558 bool "Remove the kernel mapping in user mode"
2560 depends on (X86_64 || X86_PAE)
2562 This feature reduces the number of hardware side channels by
2563 ensuring that the majority of kernel addresses are not mapped
2566 See Documentation/arch/x86/pti.rst for more details.
2569 bool "Avoid speculative indirect branches in kernel"
2570 select OBJTOOL if HAVE_OBJTOOL
2573 Compile kernel with the retpoline compiler options to guard against
2574 kernel-to-user data leaks by avoiding speculative indirect
2575 branches. Requires a compiler with -mindirect-branch=thunk-extern
2576 support for full protection. The kernel may run slower.
2579 bool "Enable return-thunks"
2580 depends on RETPOLINE && CC_HAS_RETURN_THUNK
2581 select OBJTOOL if HAVE_OBJTOOL
2584 Compile the kernel with the return-thunks compiler option to guard
2585 against kernel-to-user data leaks by avoiding return speculation.
2586 Requires a compiler with -mfunction-return=thunk-extern
2587 support for full protection. The kernel may run slower.
2589 config CPU_UNRET_ENTRY
2590 bool "Enable UNRET on kernel entry"
2591 depends on CPU_SUP_AMD && RETHUNK && X86_64
2594 Compile the kernel with support for the retbleed=unret mitigation.
2596 config CALL_DEPTH_TRACKING
2597 bool "Mitigate RSB underflow with call depth tracking"
2598 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2599 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2603 Compile the kernel with call depth tracking to mitigate the Intel
2604 SKL Return-Speculation-Buffer (RSB) underflow issue. The
2605 mitigation is off by default and needs to be enabled on the
2606 kernel command line via the retbleed=stuff option. For
2607 non-affected systems the overhead of this option is marginal as
2608 the call depth tracking is using run-time generated call thunks
2609 in a compiler generated padding area and call patching. This
2610 increases text size by ~5%. For non affected systems this space
2611 is unused. On affected SKL systems this results in a significant
2612 performance gain over the IBRS mitigation.
2614 config CALL_THUNKS_DEBUG
2615 bool "Enable call thunks and call depth tracking debugging"
2616 depends on CALL_DEPTH_TRACKING
2617 select FUNCTION_ALIGNMENT_32B
2620 Enable call/ret counters for imbalance detection and build in
2621 a noisy dmesg about callthunks generation and call patching for
2622 trouble shooting. The debug prints need to be enabled on the
2623 kernel command line with 'debug-callthunks'.
2624 Only enable this when you are debugging call thunks as this
2625 creates a noticeable runtime overhead. If unsure say N.
2627 config CPU_IBPB_ENTRY
2628 bool "Enable IBPB on kernel entry"
2629 depends on CPU_SUP_AMD && X86_64
2632 Compile the kernel with support for the retbleed=ibpb mitigation.
2634 config CPU_IBRS_ENTRY
2635 bool "Enable IBRS on kernel entry"
2636 depends on CPU_SUP_INTEL && X86_64
2639 Compile the kernel with support for the spectre_v2=ibrs mitigation.
2640 This mitigates both spectre_v2 and retbleed at great cost to
2644 bool "Mitigate Straight-Line-Speculation"
2645 depends on CC_HAS_SLS && X86_64
2646 select OBJTOOL if HAVE_OBJTOOL
2649 Compile the kernel with straight-line-speculation options to guard
2650 against straight line speculation. The kernel image might be slightly
2655 config ARCH_HAS_ADD_PAGES
2657 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2659 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2662 menu "Power management and ACPI options"
2664 config ARCH_HIBERNATION_HEADER
2666 depends on HIBERNATION
2668 source "kernel/power/Kconfig"
2670 source "drivers/acpi/Kconfig"
2677 tristate "APM (Advanced Power Management) BIOS support"
2678 depends on X86_32 && PM_SLEEP
2680 APM is a BIOS specification for saving power using several different
2681 techniques. This is mostly useful for battery powered laptops with
2682 APM compliant BIOSes. If you say Y here, the system time will be
2683 reset after a RESUME operation, the /proc/apm device will provide
2684 battery status information, and user-space programs will receive
2685 notification of APM "events" (e.g. battery status change).
2687 If you select "Y" here, you can disable actual use of the APM
2688 BIOS by passing the "apm=off" option to the kernel at boot time.
2690 Note that the APM support is almost completely disabled for
2691 machines with more than one CPU.
2693 In order to use APM, you will need supporting software. For location
2694 and more information, read <file:Documentation/power/apm-acpi.rst>
2695 and the Battery Powered Linux mini-HOWTO, available from
2696 <http://www.tldp.org/docs.html#howto>.
2698 This driver does not spin down disk drives (see the hdparm(8)
2699 manpage ("man 8 hdparm") for that), and it doesn't turn off
2700 VESA-compliant "green" monitors.
2702 This driver does not support the TI 4000M TravelMate and the ACER
2703 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2704 desktop machines also don't have compliant BIOSes, and this driver
2705 may cause those machines to panic during the boot phase.
2707 Generally, if you don't have a battery in your machine, there isn't
2708 much point in using this driver and you should say N. If you get
2709 random kernel OOPSes or reboots that don't seem to be related to
2710 anything, try disabling/enabling this option (or disabling/enabling
2713 Some other things you should try when experiencing seemingly random,
2716 1) make sure that you have enough swap space and that it is
2718 2) pass the "idle=poll" option to the kernel
2719 3) switch on floating point emulation in the kernel and pass
2720 the "no387" option to the kernel
2721 4) pass the "floppy=nodma" option to the kernel
2722 5) pass the "mem=4M" option to the kernel (thereby disabling
2723 all but the first 4 MB of RAM)
2724 6) make sure that the CPU is not over clocked.
2725 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2726 8) disable the cache from your BIOS settings
2727 9) install a fan for the video card or exchange video RAM
2728 10) install a better fan for the CPU
2729 11) exchange RAM chips
2730 12) exchange the motherboard.
2732 To compile this driver as a module, choose M here: the
2733 module will be called apm.
2737 config APM_IGNORE_USER_SUSPEND
2738 bool "Ignore USER SUSPEND"
2740 This option will ignore USER SUSPEND requests. On machines with a
2741 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2742 series notebooks, it is necessary to say Y because of a BIOS bug.
2744 config APM_DO_ENABLE
2745 bool "Enable PM at boot time"
2747 Enable APM features at boot time. From page 36 of the APM BIOS
2748 specification: "When disabled, the APM BIOS does not automatically
2749 power manage devices, enter the Standby State, enter the Suspend
2750 State, or take power saving steps in response to CPU Idle calls."
2751 This driver will make CPU Idle calls when Linux is idle (unless this
2752 feature is turned off -- see "Do CPU IDLE calls", below). This
2753 should always save battery power, but more complicated APM features
2754 will be dependent on your BIOS implementation. You may need to turn
2755 this option off if your computer hangs at boot time when using APM
2756 support, or if it beeps continuously instead of suspending. Turn
2757 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2758 T400CDT. This is off by default since most machines do fine without
2763 bool "Make CPU Idle calls when idle"
2765 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2766 On some machines, this can activate improved power savings, such as
2767 a slowed CPU clock rate, when the machine is idle. These idle calls
2768 are made after the idle loop has run for some length of time (e.g.,
2769 333 mS). On some machines, this will cause a hang at boot time or
2770 whenever the CPU becomes idle. (On machines with more than one CPU,
2771 this option does nothing.)
2773 config APM_DISPLAY_BLANK
2774 bool "Enable console blanking using APM"
2776 Enable console blanking using the APM. Some laptops can use this to
2777 turn off the LCD backlight when the screen blanker of the Linux
2778 virtual console blanks the screen. Note that this is only used by
2779 the virtual console screen blanker, and won't turn off the backlight
2780 when using the X Window system. This also doesn't have anything to
2781 do with your VESA-compliant power-saving monitor. Further, this
2782 option doesn't work for all laptops -- it might not turn off your
2783 backlight at all, or it might print a lot of errors to the console,
2784 especially if you are using gpm.
2786 config APM_ALLOW_INTS
2787 bool "Allow interrupts during APM BIOS calls"
2789 Normally we disable external interrupts while we are making calls to
2790 the APM BIOS as a measure to lessen the effects of a badly behaving
2791 BIOS implementation. The BIOS should reenable interrupts if it
2792 needs to. Unfortunately, some BIOSes do not -- especially those in
2793 many of the newer IBM Thinkpads. If you experience hangs when you
2794 suspend, try setting this to Y. Otherwise, say N.
2798 source "drivers/cpufreq/Kconfig"
2800 source "drivers/cpuidle/Kconfig"
2802 source "drivers/idle/Kconfig"
2806 menu "Bus options (PCI etc.)"
2809 prompt "PCI access mode"
2810 depends on X86_32 && PCI
2813 On PCI systems, the BIOS can be used to detect the PCI devices and
2814 determine their configuration. However, some old PCI motherboards
2815 have BIOS bugs and may crash if this is done. Also, some embedded
2816 PCI-based systems don't have any BIOS at all. Linux can also try to
2817 detect the PCI hardware directly without using the BIOS.
2819 With this option, you can specify how Linux should detect the
2820 PCI devices. If you choose "BIOS", the BIOS will be used,
2821 if you choose "Direct", the BIOS won't be used, and if you
2822 choose "MMConfig", then PCI Express MMCONFIG will be used.
2823 If you choose "Any", the kernel will try MMCONFIG, then the
2824 direct access method and falls back to the BIOS if that doesn't
2825 work. If unsure, go with the default, which is "Any".
2830 config PCI_GOMMCONFIG
2847 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2849 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2852 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2855 bool "Support mmconfig PCI config space access" if X86_64
2857 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2858 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2862 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2866 depends on PCI && XEN
2868 config MMCONF_FAM10H
2870 depends on X86_64 && PCI_MMCONFIG && ACPI
2872 config PCI_CNB20LE_QUIRK
2873 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2876 Read the PCI windows out of the CNB20LE host bridge. This allows
2877 PCI hotplug to work on systems with the CNB20LE chipset which do
2880 There's no public spec for this chipset, and this functionality
2881 is known to be incomplete.
2883 You should say N unless you know you need this.
2886 bool "ISA bus support on modern systems" if EXPERT
2888 Expose ISA bus device drivers and options available for selection and
2889 configuration. Enable this option if your target machine has an ISA
2890 bus. ISA is an older system, displaced by PCI and newer bus
2891 architectures -- if your target machine is modern, it probably does
2892 not have an ISA bus.
2896 # x86_64 have no ISA slots, but can have ISA-style DMA.
2898 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2901 Enables ISA-style DMA support for devices requiring such controllers.
2909 Find out whether you have ISA slots on your motherboard. ISA is the
2910 name of a bus system, i.e. the way the CPU talks to the other stuff
2911 inside your box. Other bus systems are PCI, EISA, MicroChannel
2912 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2913 newer boards don't support it. If you have ISA, say Y, otherwise N.
2916 tristate "NatSemi SCx200 support"
2918 This provides basic support for National Semiconductor's
2919 (now AMD's) Geode processors. The driver probes for the
2920 PCI-IDs of several on-chip devices, so its a good dependency
2921 for other scx200_* drivers.
2923 If compiled as a module, the driver is named scx200.
2925 config SCx200HR_TIMER
2926 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2930 This driver provides a clocksource built upon the on-chip
2931 27MHz high-resolution timer. Its also a workaround for
2932 NSC Geode SC-1100's buggy TSC, which loses time when the
2933 processor goes idle (as is done by the scheduler). The
2934 other workaround is idle=poll boot option.
2937 bool "One Laptop Per Child support"
2945 Add support for detecting the unique features of the OLPC
2949 bool "OLPC XO-1 Power Management"
2950 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2952 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2955 bool "OLPC XO-1 Real Time Clock"
2956 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2958 Add support for the XO-1 real time clock, which can be used as a
2959 programmable wakeup source.
2962 bool "OLPC XO-1 SCI extras"
2963 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2967 Add support for SCI-based features of the OLPC XO-1 laptop:
2968 - EC-driven system wakeups
2972 - AC adapter status updates
2973 - Battery status updates
2975 config OLPC_XO15_SCI
2976 bool "OLPC XO-1.5 SCI extras"
2977 depends on OLPC && ACPI
2980 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2981 - EC-driven system wakeups
2982 - AC adapter status updates
2983 - Battery status updates
2986 bool "PCEngines ALIX System Support (LED setup)"
2989 This option enables system support for the PCEngines ALIX.
2990 At present this just sets up LEDs for GPIO control on
2991 ALIX2/3/6 boards. However, other system specific setup should
2994 Note: You must still enable the drivers for GPIO and LED support
2995 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2997 Note: You have to set alix.force=1 for boards with Award BIOS.
3000 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
3003 This option enables system support for the Soekris Engineering net5501.
3006 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
3010 This option enables system support for the Traverse Technologies GEOS.
3013 bool "Technologic Systems TS-5500 platform support"
3015 select CHECK_SIGNATURE
3019 This option enables system support for the Technologic Systems TS-5500.
3025 depends on CPU_SUP_AMD && PCI
3029 menu "Binary Emulations"
3031 config IA32_EMULATION
3032 bool "IA32 Emulation"
3034 select ARCH_WANT_OLD_COMPAT_IPC
3036 select COMPAT_OLD_SIGACTION
3038 Include code to run legacy 32-bit programs under a
3039 64-bit kernel. You should likely turn this on, unless you're
3040 100% sure that you don't have any 32-bit programs left.
3043 bool "x32 ABI for 64-bit mode"
3045 # llvm-objcopy does not convert x86_64 .note.gnu.property or
3046 # compressed debug sections to x86_x32 properly:
3047 # https://github.com/ClangBuiltLinux/linux/issues/514
3048 # https://github.com/ClangBuiltLinux/linux/issues/1141
3049 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3051 Include code to run binaries for the x32 native 32-bit ABI
3052 for 64-bit processors. An x32 process gets access to the
3053 full 64-bit register file and wide data path while leaving
3054 pointers at 32 bits for smaller memory footprint.
3058 depends on IA32_EMULATION || X86_32
3060 select OLD_SIGSUSPEND3
3064 depends on IA32_EMULATION || X86_X32_ABI
3066 config COMPAT_FOR_U64_ALIGNMENT
3072 config HAVE_ATOMIC_IOMAP
3076 source "arch/x86/kvm/Kconfig"
3078 source "arch/x86/Kconfig.assembler"