compiler_attributes.h: cleanups for GCC 4.9+
[linux-2.6-block.git] / arch / x86 / Kconfig
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1# SPDX-License-Identifier: GPL-2.0
2# Select 32 or 64 bit
3config 64BIT
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
6 help
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
9
10config X86_32
11 def_bool y
12 depends on !64BIT
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
15 select CLKSRC_I8253
16 select CLONE_BACKWARDS
17 select GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
19 select KMAP_LOCAL
20 select MODULES_USE_ELF_REL
21 select OLD_SIGACTION
22 select ARCH_SPLIT_ARG64
23
24config X86_64
25 def_bool y
26 depends on 64BIT
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_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
34 select SWIOTLB
35 select ARCH_HAS_ELFCORE_COMPAT
36
37config FORCE_DYNAMIC_FTRACE
38 def_bool y
39 depends on X86_32
40 depends on FUNCTION_TRACER
41 select DYNAMIC_FTRACE
42 help
43 We keep the static function tracing (!DYNAMIC_FTRACE) around
44 in order to test the non static function tracing in the
45 generic code, as other architectures still use it. But we
46 only need to keep it around for x86_64. No need to keep it
47 for x86_32. For x86_32, force DYNAMIC_FTRACE.
48#
49# Arch settings
50#
51# ( Note that options that are marked 'if X86_64' could in principle be
52# ported to 32-bit as well. )
53#
54config X86
55 def_bool y
56 #
57 # Note: keep this list sorted alphabetically
58 #
59 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
60 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
61 select ARCH_32BIT_OFF_T if X86_32
62 select ARCH_CLOCKSOURCE_INIT
63 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
64 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 || (X86_32 && HIGHMEM)
65 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
66 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if X86_64 || X86_PAE
67 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
68 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
69 select ARCH_HAS_CACHE_LINE_SIZE
70 select ARCH_HAS_DEBUG_VIRTUAL
71 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
72 select ARCH_HAS_DEVMEM_IS_ALLOWED
73 select ARCH_HAS_EARLY_DEBUG if KGDB
74 select ARCH_HAS_ELF_RANDOMIZE
75 select ARCH_HAS_FAST_MULTIPLIER
76 select ARCH_HAS_FILTER_PGPROT
77 select ARCH_HAS_FORTIFY_SOURCE
78 select ARCH_HAS_GCOV_PROFILE_ALL
79 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
80 select ARCH_HAS_MEM_ENCRYPT
81 select ARCH_HAS_MEMBARRIER_SYNC_CORE
82 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
83 select ARCH_HAS_PMEM_API if X86_64
84 select ARCH_HAS_PTE_DEVMAP if X86_64
85 select ARCH_HAS_PTE_SPECIAL
86 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
87 select ARCH_HAS_COPY_MC if X86_64
88 select ARCH_HAS_SET_MEMORY
89 select ARCH_HAS_SET_DIRECT_MAP
90 select ARCH_HAS_STRICT_KERNEL_RWX
91 select ARCH_HAS_STRICT_MODULE_RWX
92 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
93 select ARCH_HAS_SYSCALL_WRAPPER
94 select ARCH_HAS_UBSAN_SANITIZE_ALL
95 select ARCH_HAS_DEBUG_WX
96 select ARCH_HAVE_NMI_SAFE_CMPXCHG
97 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
98 select ARCH_MIGHT_HAVE_PC_PARPORT
99 select ARCH_MIGHT_HAVE_PC_SERIO
100 select ARCH_STACKWALK
101 select ARCH_SUPPORTS_ACPI
102 select ARCH_SUPPORTS_ATOMIC_RMW
103 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
104 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
105 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
106 select ARCH_SUPPORTS_LTO_CLANG
107 select ARCH_SUPPORTS_LTO_CLANG_THIN
108 select ARCH_USE_BUILTIN_BSWAP
109 select ARCH_USE_MEMTEST
110 select ARCH_USE_QUEUED_RWLOCKS
111 select ARCH_USE_QUEUED_SPINLOCKS
112 select ARCH_USE_SYM_ANNOTATIONS
113 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
114 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
115 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
116 select ARCH_WANT_HUGE_PMD_SHARE
117 select ARCH_WANT_LD_ORPHAN_WARN
118 select ARCH_WANTS_THP_SWAP if X86_64
119 select BUILDTIME_TABLE_SORT
120 select CLKEVT_I8253
121 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
122 select CLOCKSOURCE_WATCHDOG
123 select DCACHE_WORD_ACCESS
124 select EDAC_ATOMIC_SCRUB
125 select EDAC_SUPPORT
126 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
127 select GENERIC_CLOCKEVENTS_MIN_ADJUST
128 select GENERIC_CMOS_UPDATE
129 select GENERIC_CPU_AUTOPROBE
130 select GENERIC_CPU_VULNERABILITIES
131 select GENERIC_EARLY_IOREMAP
132 select GENERIC_ENTRY
133 select GENERIC_FIND_FIRST_BIT
134 select GENERIC_IOMAP
135 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
136 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
137 select GENERIC_IRQ_MIGRATION if SMP
138 select GENERIC_IRQ_PROBE
139 select GENERIC_IRQ_RESERVATION_MODE
140 select GENERIC_IRQ_SHOW
141 select GENERIC_PENDING_IRQ if SMP
142 select GENERIC_PTDUMP
143 select GENERIC_SMP_IDLE_THREAD
144 select GENERIC_STRNCPY_FROM_USER
145 select GENERIC_STRNLEN_USER
146 select GENERIC_TIME_VSYSCALL
147 select GENERIC_GETTIMEOFDAY
148 select GENERIC_VDSO_TIME_NS
149 select GUP_GET_PTE_LOW_HIGH if X86_PAE
150 select HARDIRQS_SW_RESEND
151 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
152 select HAVE_ACPI_APEI if ACPI
153 select HAVE_ACPI_APEI_NMI if ACPI
154 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
155 select HAVE_ARCH_AUDITSYSCALL
156 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
157 select HAVE_ARCH_JUMP_LABEL
158 select HAVE_ARCH_JUMP_LABEL_RELATIVE
159 select HAVE_ARCH_KASAN if X86_64
160 select HAVE_ARCH_KASAN_VMALLOC if X86_64
161 select HAVE_ARCH_KFENCE
162 select HAVE_ARCH_KGDB
163 select HAVE_ARCH_MMAP_RND_BITS if MMU
164 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
165 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
166 select HAVE_ARCH_PREL32_RELOCATIONS
167 select HAVE_ARCH_SECCOMP_FILTER
168 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
169 select HAVE_ARCH_STACKLEAK
170 select HAVE_ARCH_TRACEHOOK
171 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
172 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
173 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
174 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
175 select HAVE_ARCH_VMAP_STACK if X86_64
176 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
177 select HAVE_ARCH_WITHIN_STACK_FRAMES
178 select HAVE_ASM_MODVERSIONS
179 select HAVE_CMPXCHG_DOUBLE
180 select HAVE_CMPXCHG_LOCAL
181 select HAVE_CONTEXT_TRACKING if X86_64
182 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
183 select HAVE_C_RECORDMCOUNT
184 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
185 select HAVE_DEBUG_KMEMLEAK
186 select HAVE_DMA_CONTIGUOUS
187 select HAVE_DYNAMIC_FTRACE
188 select HAVE_DYNAMIC_FTRACE_WITH_REGS
189 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
190 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
191 select HAVE_EBPF_JIT
192 select HAVE_EFFICIENT_UNALIGNED_ACCESS
193 select HAVE_EISA
194 select HAVE_EXIT_THREAD
195 select HAVE_FAST_GUP
196 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
197 select HAVE_FTRACE_MCOUNT_RECORD
198 select HAVE_FUNCTION_GRAPH_TRACER
199 select HAVE_FUNCTION_TRACER
200 select HAVE_GCC_PLUGINS
201 select HAVE_HW_BREAKPOINT
202 select HAVE_IDE
203 select HAVE_IOREMAP_PROT
204 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
205 select HAVE_IRQ_TIME_ACCOUNTING
206 select HAVE_KERNEL_BZIP2
207 select HAVE_KERNEL_GZIP
208 select HAVE_KERNEL_LZ4
209 select HAVE_KERNEL_LZMA
210 select HAVE_KERNEL_LZO
211 select HAVE_KERNEL_XZ
212 select HAVE_KERNEL_ZSTD
213 select HAVE_KPROBES
214 select HAVE_KPROBES_ON_FTRACE
215 select HAVE_FUNCTION_ERROR_INJECTION
216 select HAVE_KRETPROBES
217 select HAVE_KVM
218 select HAVE_LIVEPATCH if X86_64
219 select HAVE_MIXED_BREAKPOINTS_REGS
220 select HAVE_MOD_ARCH_SPECIFIC
221 select HAVE_MOVE_PMD
222 select HAVE_MOVE_PUD
223 select HAVE_NMI
224 select HAVE_OPTPROBES
225 select HAVE_PCSPKR_PLATFORM
226 select HAVE_PERF_EVENTS
227 select HAVE_PERF_EVENTS_NMI
228 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
229 select HAVE_PCI
230 select HAVE_PERF_REGS
231 select HAVE_PERF_USER_STACK_DUMP
232 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
233 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
234 select HAVE_REGS_AND_STACK_ACCESS_API
235 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
236 select HAVE_FUNCTION_ARG_ACCESS_API
237 select HAVE_SOFTIRQ_ON_OWN_STACK
238 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
239 select HAVE_STACK_VALIDATION if X86_64
240 select HAVE_STATIC_CALL
241 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
242 select HAVE_PREEMPT_DYNAMIC
243 select HAVE_RSEQ
244 select HAVE_SYSCALL_TRACEPOINTS
245 select HAVE_UNSTABLE_SCHED_CLOCK
246 select HAVE_USER_RETURN_NOTIFIER
247 select HAVE_GENERIC_VDSO
248 select HOTPLUG_SMT if SMP
249 select IRQ_FORCED_THREADING
250 select NEED_SG_DMA_LENGTH
251 select PCI_DOMAINS if PCI
252 select PCI_LOCKLESS_CONFIG if PCI
253 select PERF_EVENTS
254 select RTC_LIB
255 select RTC_MC146818_LIB
256 select SPARSE_IRQ
257 select SRCU
258 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
259 select SYSCTL_EXCEPTION_TRACE
260 select THREAD_INFO_IN_TASK
261 select USER_STACKTRACE_SUPPORT
262 select VIRT_TO_BUS
263 select HAVE_ARCH_KCSAN if X86_64
264 select X86_FEATURE_NAMES if PROC_FS
265 select PROC_PID_ARCH_STATUS if PROC_FS
266 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
267
268config INSTRUCTION_DECODER
269 def_bool y
270 depends on KPROBES || PERF_EVENTS || UPROBES
271
272config OUTPUT_FORMAT
273 string
274 default "elf32-i386" if X86_32
275 default "elf64-x86-64" if X86_64
276
277config LOCKDEP_SUPPORT
278 def_bool y
279
280config STACKTRACE_SUPPORT
281 def_bool y
282
283config MMU
284 def_bool y
285
286config ARCH_MMAP_RND_BITS_MIN
287 default 28 if 64BIT
288 default 8
289
290config ARCH_MMAP_RND_BITS_MAX
291 default 32 if 64BIT
292 default 16
293
294config ARCH_MMAP_RND_COMPAT_BITS_MIN
295 default 8
296
297config ARCH_MMAP_RND_COMPAT_BITS_MAX
298 default 16
299
300config SBUS
301 bool
302
303config GENERIC_ISA_DMA
304 def_bool y
305 depends on ISA_DMA_API
306
307config GENERIC_BUG
308 def_bool y
309 depends on BUG
310 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
311
312config GENERIC_BUG_RELATIVE_POINTERS
313 bool
314
315config ARCH_MAY_HAVE_PC_FDC
316 def_bool y
317 depends on ISA_DMA_API
318
319config GENERIC_CALIBRATE_DELAY
320 def_bool y
321
322config ARCH_HAS_CPU_RELAX
323 def_bool y
324
325config ARCH_HAS_FILTER_PGPROT
326 def_bool y
327
328config HAVE_SETUP_PER_CPU_AREA
329 def_bool y
330
331config NEED_PER_CPU_EMBED_FIRST_CHUNK
332 def_bool y
333
334config NEED_PER_CPU_PAGE_FIRST_CHUNK
335 def_bool y
336
337config ARCH_HIBERNATION_POSSIBLE
338 def_bool y
339
340config ARCH_SUSPEND_POSSIBLE
341 def_bool y
342
343config ARCH_WANT_GENERAL_HUGETLB
344 def_bool y
345
346config ZONE_DMA32
347 def_bool y if X86_64
348
349config AUDIT_ARCH
350 def_bool y if X86_64
351
352config KASAN_SHADOW_OFFSET
353 hex
354 depends on KASAN
355 default 0xdffffc0000000000
356
357config HAVE_INTEL_TXT
358 def_bool y
359 depends on INTEL_IOMMU && ACPI
360
361config X86_32_SMP
362 def_bool y
363 depends on X86_32 && SMP
364
365config X86_64_SMP
366 def_bool y
367 depends on X86_64 && SMP
368
369config ARCH_SUPPORTS_UPROBES
370 def_bool y
371
372config FIX_EARLYCON_MEM
373 def_bool y
374
375config DYNAMIC_PHYSICAL_MASK
376 bool
377
378config PGTABLE_LEVELS
379 int
380 default 5 if X86_5LEVEL
381 default 4 if X86_64
382 default 3 if X86_PAE
383 default 2
384
385config CC_HAS_SANE_STACKPROTECTOR
386 bool
387 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
388 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
389 help
390 We have to make sure stack protector is unconditionally disabled if
391 the compiler produces broken code or if it does not let us control
392 the segment on 32-bit kernels.
393
394menu "Processor type and features"
395
396config ZONE_DMA
397 bool "DMA memory allocation support" if EXPERT
398 default y
399 help
400 DMA memory allocation support allows devices with less than 32-bit
401 addressing to allocate within the first 16MB of address space.
402 Disable if no such devices will be used.
403
404 If unsure, say Y.
405
406config SMP
407 bool "Symmetric multi-processing support"
408 help
409 This enables support for systems with more than one CPU. If you have
410 a system with only one CPU, say N. If you have a system with more
411 than one CPU, say Y.
412
413 If you say N here, the kernel will run on uni- and multiprocessor
414 machines, but will use only one CPU of a multiprocessor machine. If
415 you say Y here, the kernel will run on many, but not all,
416 uniprocessor machines. On a uniprocessor machine, the kernel
417 will run faster if you say N here.
418
419 Note that if you say Y here and choose architecture "586" or
420 "Pentium" under "Processor family", the kernel will not work on 486
421 architectures. Similarly, multiprocessor kernels for the "PPro"
422 architecture may not work on all Pentium based boards.
423
424 People using multiprocessor machines who say Y here should also say
425 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
426 Management" code will be disabled if you say Y here.
427
428 See also <file:Documentation/x86/i386/IO-APIC.rst>,
429 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
430 <http://www.tldp.org/docs.html#howto>.
431
432 If you don't know what to do here, say N.
433
434config X86_FEATURE_NAMES
435 bool "Processor feature human-readable names" if EMBEDDED
436 default y
437 help
438 This option compiles in a table of x86 feature bits and corresponding
439 names. This is required to support /proc/cpuinfo and a few kernel
440 messages. You can disable this to save space, at the expense of
441 making those few kernel messages show numeric feature bits instead.
442
443 If in doubt, say Y.
444
445config X86_X2APIC
446 bool "Support x2apic"
447 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
448 help
449 This enables x2apic support on CPUs that have this feature.
450
451 This allows 32-bit apic IDs (so it can support very large systems),
452 and accesses the local apic via MSRs not via mmio.
453
454 If you don't know what to do here, say N.
455
456config X86_MPPARSE
457 bool "Enable MPS table" if ACPI
458 default y
459 depends on X86_LOCAL_APIC
460 help
461 For old smp systems that do not have proper acpi support. Newer systems
462 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
463
464config GOLDFISH
465 def_bool y
466 depends on X86_GOLDFISH
467
468config RETPOLINE
469 bool "Avoid speculative indirect branches in kernel"
470 default y
471 help
472 Compile kernel with the retpoline compiler options to guard against
473 kernel-to-user data leaks by avoiding speculative indirect
474 branches. Requires a compiler with -mindirect-branch=thunk-extern
475 support for full protection. The kernel may run slower.
476
477config X86_CPU_RESCTRL
478 bool "x86 CPU resource control support"
479 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
480 select KERNFS
481 select PROC_CPU_RESCTRL if PROC_FS
482 help
483 Enable x86 CPU resource control support.
484
485 Provide support for the allocation and monitoring of system resources
486 usage by the CPU.
487
488 Intel calls this Intel Resource Director Technology
489 (Intel(R) RDT). More information about RDT can be found in the
490 Intel x86 Architecture Software Developer Manual.
491
492 AMD calls this AMD Platform Quality of Service (AMD QoS).
493 More information about AMD QoS can be found in the AMD64 Technology
494 Platform Quality of Service Extensions manual.
495
496 Say N if unsure.
497
498if X86_32
499config X86_BIGSMP
500 bool "Support for big SMP systems with more than 8 CPUs"
501 depends on SMP
502 help
503 This option is needed for the systems that have more than 8 CPUs.
504
505config X86_EXTENDED_PLATFORM
506 bool "Support for extended (non-PC) x86 platforms"
507 default y
508 help
509 If you disable this option then the kernel will only support
510 standard PC platforms. (which covers the vast majority of
511 systems out there.)
512
513 If you enable this option then you'll be able to select support
514 for the following (non-PC) 32 bit x86 platforms:
515 Goldfish (Android emulator)
516 AMD Elan
517 RDC R-321x SoC
518 SGI 320/540 (Visual Workstation)
519 STA2X11-based (e.g. Northville)
520 Moorestown MID devices
521
522 If you have one of these systems, or if you want to build a
523 generic distribution kernel, say Y here - otherwise say N.
524endif
525
526if X86_64
527config X86_EXTENDED_PLATFORM
528 bool "Support for extended (non-PC) x86 platforms"
529 default y
530 help
531 If you disable this option then the kernel will only support
532 standard PC platforms. (which covers the vast majority of
533 systems out there.)
534
535 If you enable this option then you'll be able to select support
536 for the following (non-PC) 64 bit x86 platforms:
537 Numascale NumaChip
538 ScaleMP vSMP
539 SGI Ultraviolet
540
541 If you have one of these systems, or if you want to build a
542 generic distribution kernel, say Y here - otherwise say N.
543endif
544# This is an alphabetically sorted list of 64 bit extended platforms
545# Please maintain the alphabetic order if and when there are additions
546config X86_NUMACHIP
547 bool "Numascale NumaChip"
548 depends on X86_64
549 depends on X86_EXTENDED_PLATFORM
550 depends on NUMA
551 depends on SMP
552 depends on X86_X2APIC
553 depends on PCI_MMCONFIG
554 help
555 Adds support for Numascale NumaChip large-SMP systems. Needed to
556 enable more than ~168 cores.
557 If you don't have one of these, you should say N here.
558
559config X86_VSMP
560 bool "ScaleMP vSMP"
561 select HYPERVISOR_GUEST
562 select PARAVIRT
563 depends on X86_64 && PCI
564 depends on X86_EXTENDED_PLATFORM
565 depends on SMP
566 help
567 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
568 supposed to run on these EM64T-based machines. Only choose this option
569 if you have one of these machines.
570
571config X86_UV
572 bool "SGI Ultraviolet"
573 depends on X86_64
574 depends on X86_EXTENDED_PLATFORM
575 depends on NUMA
576 depends on EFI
577 depends on KEXEC_CORE
578 depends on X86_X2APIC
579 depends on PCI
580 help
581 This option is needed in order to support SGI Ultraviolet systems.
582 If you don't have one of these, you should say N here.
583
584# Following is an alphabetically sorted list of 32 bit extended platforms
585# Please maintain the alphabetic order if and when there are additions
586
587config X86_GOLDFISH
588 bool "Goldfish (Virtual Platform)"
589 depends on X86_EXTENDED_PLATFORM
590 help
591 Enable support for the Goldfish virtual platform used primarily
592 for Android development. Unless you are building for the Android
593 Goldfish emulator say N here.
594
595config X86_INTEL_CE
596 bool "CE4100 TV platform"
597 depends on PCI
598 depends on PCI_GODIRECT
599 depends on X86_IO_APIC
600 depends on X86_32
601 depends on X86_EXTENDED_PLATFORM
602 select X86_REBOOTFIXUPS
603 select OF
604 select OF_EARLY_FLATTREE
605 help
606 Select for the Intel CE media processor (CE4100) SOC.
607 This option compiles in support for the CE4100 SOC for settop
608 boxes and media devices.
609
610config X86_INTEL_MID
611 bool "Intel MID platform support"
612 depends on X86_EXTENDED_PLATFORM
613 depends on X86_PLATFORM_DEVICES
614 depends on PCI
615 depends on X86_64 || (PCI_GOANY && X86_32)
616 depends on X86_IO_APIC
617 select I2C
618 select DW_APB_TIMER
619 select APB_TIMER
620 select INTEL_SCU_PCI
621 select MFD_INTEL_MSIC
622 help
623 Select to build a kernel capable of supporting Intel MID (Mobile
624 Internet Device) platform systems which do not have the PCI legacy
625 interfaces. If you are building for a PC class system say N here.
626
627 Intel MID platforms are based on an Intel processor and chipset which
628 consume less power than most of the x86 derivatives.
629
630config X86_INTEL_QUARK
631 bool "Intel Quark platform support"
632 depends on X86_32
633 depends on X86_EXTENDED_PLATFORM
634 depends on X86_PLATFORM_DEVICES
635 depends on X86_TSC
636 depends on PCI
637 depends on PCI_GOANY
638 depends on X86_IO_APIC
639 select IOSF_MBI
640 select INTEL_IMR
641 select COMMON_CLK
642 help
643 Select to include support for Quark X1000 SoC.
644 Say Y here if you have a Quark based system such as the Arduino
645 compatible Intel Galileo.
646
647config X86_INTEL_LPSS
648 bool "Intel Low Power Subsystem Support"
649 depends on X86 && ACPI && PCI
650 select COMMON_CLK
651 select PINCTRL
652 select IOSF_MBI
653 help
654 Select to build support for Intel Low Power Subsystem such as
655 found on Intel Lynxpoint PCH. Selecting this option enables
656 things like clock tree (common clock framework) and pincontrol
657 which are needed by the LPSS peripheral drivers.
658
659config X86_AMD_PLATFORM_DEVICE
660 bool "AMD ACPI2Platform devices support"
661 depends on ACPI
662 select COMMON_CLK
663 select PINCTRL
664 help
665 Select to interpret AMD specific ACPI device to platform device
666 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
667 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
668 implemented under PINCTRL subsystem.
669
670config IOSF_MBI
671 tristate "Intel SoC IOSF Sideband support for SoC platforms"
672 depends on PCI
673 help
674 This option enables sideband register access support for Intel SoC
675 platforms. On these platforms the IOSF sideband is used in lieu of
676 MSR's for some register accesses, mostly but not limited to thermal
677 and power. Drivers may query the availability of this device to
678 determine if they need the sideband in order to work on these
679 platforms. The sideband is available on the following SoC products.
680 This list is not meant to be exclusive.
681 - BayTrail
682 - Braswell
683 - Quark
684
685 You should say Y if you are running a kernel on one of these SoC's.
686
687config IOSF_MBI_DEBUG
688 bool "Enable IOSF sideband access through debugfs"
689 depends on IOSF_MBI && DEBUG_FS
690 help
691 Select this option to expose the IOSF sideband access registers (MCR,
692 MDR, MCRX) through debugfs to write and read register information from
693 different units on the SoC. This is most useful for obtaining device
694 state information for debug and analysis. As this is a general access
695 mechanism, users of this option would have specific knowledge of the
696 device they want to access.
697
698 If you don't require the option or are in doubt, say N.
699
700config X86_RDC321X
701 bool "RDC R-321x SoC"
702 depends on X86_32
703 depends on X86_EXTENDED_PLATFORM
704 select M486
705 select X86_REBOOTFIXUPS
706 help
707 This option is needed for RDC R-321x system-on-chip, also known
708 as R-8610-(G).
709 If you don't have one of these chips, you should say N here.
710
711config X86_32_NON_STANDARD
712 bool "Support non-standard 32-bit SMP architectures"
713 depends on X86_32 && SMP
714 depends on X86_EXTENDED_PLATFORM
715 help
716 This option compiles in the bigsmp and STA2X11 default
717 subarchitectures. It is intended for a generic binary
718 kernel. If you select them all, kernel will probe it one by
719 one and will fallback to default.
720
721# Alphabetically sorted list of Non standard 32 bit platforms
722
723config X86_SUPPORTS_MEMORY_FAILURE
724 def_bool y
725 # MCE code calls memory_failure():
726 depends on X86_MCE
727 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
728 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
729 depends on X86_64 || !SPARSEMEM
730 select ARCH_SUPPORTS_MEMORY_FAILURE
731
732config STA2X11
733 bool "STA2X11 Companion Chip Support"
734 depends on X86_32_NON_STANDARD && PCI
735 select SWIOTLB
736 select MFD_STA2X11
737 select GPIOLIB
738 help
739 This adds support for boards based on the STA2X11 IO-Hub,
740 a.k.a. "ConneXt". The chip is used in place of the standard
741 PC chipset, so all "standard" peripherals are missing. If this
742 option is selected the kernel will still be able to boot on
743 standard PC machines.
744
745config X86_32_IRIS
746 tristate "Eurobraille/Iris poweroff module"
747 depends on X86_32
748 help
749 The Iris machines from EuroBraille do not have APM or ACPI support
750 to shut themselves down properly. A special I/O sequence is
751 needed to do so, which is what this module does at
752 kernel shutdown.
753
754 This is only for Iris machines from EuroBraille.
755
756 If unused, say N.
757
758config SCHED_OMIT_FRAME_POINTER
759 def_bool y
760 prompt "Single-depth WCHAN output"
761 depends on X86
762 help
763 Calculate simpler /proc/<PID>/wchan values. If this option
764 is disabled then wchan values will recurse back to the
765 caller function. This provides more accurate wchan values,
766 at the expense of slightly more scheduling overhead.
767
768 If in doubt, say "Y".
769
770menuconfig HYPERVISOR_GUEST
771 bool "Linux guest support"
772 help
773 Say Y here to enable options for running Linux under various hyper-
774 visors. This option enables basic hypervisor detection and platform
775 setup.
776
777 If you say N, all options in this submenu will be skipped and
778 disabled, and Linux guest support won't be built in.
779
780if HYPERVISOR_GUEST
781
782config PARAVIRT
783 bool "Enable paravirtualization code"
784 depends on HAVE_STATIC_CALL
785 help
786 This changes the kernel so it can modify itself when it is run
787 under a hypervisor, potentially improving performance significantly
788 over full virtualization. However, when run without a hypervisor
789 the kernel is theoretically slower and slightly larger.
790
791config PARAVIRT_XXL
792 bool
793
794config PARAVIRT_DEBUG
795 bool "paravirt-ops debugging"
796 depends on PARAVIRT && DEBUG_KERNEL
797 help
798 Enable to debug paravirt_ops internals. Specifically, BUG if
799 a paravirt_op is missing when it is called.
800
801config PARAVIRT_SPINLOCKS
802 bool "Paravirtualization layer for spinlocks"
803 depends on PARAVIRT && SMP
804 help
805 Paravirtualized spinlocks allow a pvops backend to replace the
806 spinlock implementation with something virtualization-friendly
807 (for example, block the virtual CPU rather than spinning).
808
809 It has a minimal impact on native kernels and gives a nice performance
810 benefit on paravirtualized KVM / Xen kernels.
811
812 If you are unsure how to answer this question, answer Y.
813
814config X86_HV_CALLBACK_VECTOR
815 def_bool n
816
817source "arch/x86/xen/Kconfig"
818
819config KVM_GUEST
820 bool "KVM Guest support (including kvmclock)"
821 depends on PARAVIRT
822 select PARAVIRT_CLOCK
823 select ARCH_CPUIDLE_HALTPOLL
824 select X86_HV_CALLBACK_VECTOR
825 default y
826 help
827 This option enables various optimizations for running under the KVM
828 hypervisor. It includes a paravirtualized clock, so that instead
829 of relying on a PIT (or probably other) emulation by the
830 underlying device model, the host provides the guest with
831 timing infrastructure such as time of day, and system time
832
833config ARCH_CPUIDLE_HALTPOLL
834 def_bool n
835 prompt "Disable host haltpoll when loading haltpoll driver"
836 help
837 If virtualized under KVM, disable host haltpoll.
838
839config PVH
840 bool "Support for running PVH guests"
841 help
842 This option enables the PVH entry point for guest virtual machines
843 as specified in the x86/HVM direct boot ABI.
844
845config PARAVIRT_TIME_ACCOUNTING
846 bool "Paravirtual steal time accounting"
847 depends on PARAVIRT
848 help
849 Select this option to enable fine granularity task steal time
850 accounting. Time spent executing other tasks in parallel with
851 the current vCPU is discounted from the vCPU power. To account for
852 that, there can be a small performance impact.
853
854 If in doubt, say N here.
855
856config PARAVIRT_CLOCK
857 bool
858
859config JAILHOUSE_GUEST
860 bool "Jailhouse non-root cell support"
861 depends on X86_64 && PCI
862 select X86_PM_TIMER
863 help
864 This option allows to run Linux as guest in a Jailhouse non-root
865 cell. You can leave this option disabled if you only want to start
866 Jailhouse and run Linux afterwards in the root cell.
867
868config ACRN_GUEST
869 bool "ACRN Guest support"
870 depends on X86_64
871 select X86_HV_CALLBACK_VECTOR
872 help
873 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
874 a flexible, lightweight reference open-source hypervisor, built with
875 real-time and safety-criticality in mind. It is built for embedded
876 IOT with small footprint and real-time features. More details can be
877 found in https://projectacrn.org/.
878
879endif #HYPERVISOR_GUEST
880
881source "arch/x86/Kconfig.cpu"
882
883config HPET_TIMER
884 def_bool X86_64
885 prompt "HPET Timer Support" if X86_32
886 help
887 Use the IA-PC HPET (High Precision Event Timer) to manage
888 time in preference to the PIT and RTC, if a HPET is
889 present.
890 HPET is the next generation timer replacing legacy 8254s.
891 The HPET provides a stable time base on SMP
892 systems, unlike the TSC, but it is more expensive to access,
893 as it is off-chip. The interface used is documented
894 in the HPET spec, revision 1.
895
896 You can safely choose Y here. However, HPET will only be
897 activated if the platform and the BIOS support this feature.
898 Otherwise the 8254 will be used for timing services.
899
900 Choose N to continue using the legacy 8254 timer.
901
902config HPET_EMULATE_RTC
903 def_bool y
904 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
905
906# Mark as expert because too many people got it wrong.
907# The code disables itself when not needed.
908config DMI
909 default y
910 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
911 bool "Enable DMI scanning" if EXPERT
912 help
913 Enabled scanning of DMI to identify machine quirks. Say Y
914 here unless you have verified that your setup is not
915 affected by entries in the DMI blacklist. Required by PNP
916 BIOS code.
917
918config GART_IOMMU
919 bool "Old AMD GART IOMMU support"
920 select DMA_OPS
921 select IOMMU_HELPER
922 select SWIOTLB
923 depends on X86_64 && PCI && AMD_NB
924 help
925 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
926 GART based hardware IOMMUs.
927
928 The GART supports full DMA access for devices with 32-bit access
929 limitations, on systems with more than 3 GB. This is usually needed
930 for USB, sound, many IDE/SATA chipsets and some other devices.
931
932 Newer systems typically have a modern AMD IOMMU, supported via
933 the CONFIG_AMD_IOMMU=y config option.
934
935 In normal configurations this driver is only active when needed:
936 there's more than 3 GB of memory and the system contains a
937 32-bit limited device.
938
939 If unsure, say Y.
940
941config MAXSMP
942 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
943 depends on X86_64 && SMP && DEBUG_KERNEL
944 select CPUMASK_OFFSTACK
945 help
946 Enable maximum number of CPUS and NUMA Nodes for this architecture.
947 If unsure, say N.
948
949#
950# The maximum number of CPUs supported:
951#
952# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
953# and which can be configured interactively in the
954# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
955#
956# The ranges are different on 32-bit and 64-bit kernels, depending on
957# hardware capabilities and scalability features of the kernel.
958#
959# ( If MAXSMP is enabled we just use the highest possible value and disable
960# interactive configuration. )
961#
962
963config NR_CPUS_RANGE_BEGIN
964 int
965 default NR_CPUS_RANGE_END if MAXSMP
966 default 1 if !SMP
967 default 2
968
969config NR_CPUS_RANGE_END
970 int
971 depends on X86_32
972 default 64 if SMP && X86_BIGSMP
973 default 8 if SMP && !X86_BIGSMP
974 default 1 if !SMP
975
976config NR_CPUS_RANGE_END
977 int
978 depends on X86_64
979 default 8192 if SMP && CPUMASK_OFFSTACK
980 default 512 if SMP && !CPUMASK_OFFSTACK
981 default 1 if !SMP
982
983config NR_CPUS_DEFAULT
984 int
985 depends on X86_32
986 default 32 if X86_BIGSMP
987 default 8 if SMP
988 default 1 if !SMP
989
990config NR_CPUS_DEFAULT
991 int
992 depends on X86_64
993 default 8192 if MAXSMP
994 default 64 if SMP
995 default 1 if !SMP
996
997config NR_CPUS
998 int "Maximum number of CPUs" if SMP && !MAXSMP
999 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1000 default NR_CPUS_DEFAULT
1001 help
1002 This allows you to specify the maximum number of CPUs which this
1003 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1004 supported value is 8192, otherwise the maximum value is 512. The
1005 minimum value which makes sense is 2.
1006
1007 This is purely to save memory: each supported CPU adds about 8KB
1008 to the kernel image.
1009
1010config SCHED_SMT
1011 def_bool y if SMP
1012
1013config SCHED_MC
1014 def_bool y
1015 prompt "Multi-core scheduler support"
1016 depends on SMP
1017 help
1018 Multi-core scheduler support improves the CPU scheduler's decision
1019 making when dealing with multi-core CPU chips at a cost of slightly
1020 increased overhead in some places. If unsure say N here.
1021
1022config SCHED_MC_PRIO
1023 bool "CPU core priorities scheduler support"
1024 depends on SCHED_MC && CPU_SUP_INTEL
1025 select X86_INTEL_PSTATE
1026 select CPU_FREQ
1027 default y
1028 help
1029 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1030 core ordering determined at manufacturing time, which allows
1031 certain cores to reach higher turbo frequencies (when running
1032 single threaded workloads) than others.
1033
1034 Enabling this kernel feature teaches the scheduler about
1035 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1036 scheduler's CPU selection logic accordingly, so that higher
1037 overall system performance can be achieved.
1038
1039 This feature will have no effect on CPUs without this feature.
1040
1041 If unsure say Y here.
1042
1043config UP_LATE_INIT
1044 def_bool y
1045 depends on !SMP && X86_LOCAL_APIC
1046
1047config X86_UP_APIC
1048 bool "Local APIC support on uniprocessors" if !PCI_MSI
1049 default PCI_MSI
1050 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1051 help
1052 A local APIC (Advanced Programmable Interrupt Controller) is an
1053 integrated interrupt controller in the CPU. If you have a single-CPU
1054 system which has a processor with a local APIC, you can say Y here to
1055 enable and use it. If you say Y here even though your machine doesn't
1056 have a local APIC, then the kernel will still run with no slowdown at
1057 all. The local APIC supports CPU-generated self-interrupts (timer,
1058 performance counters), and the NMI watchdog which detects hard
1059 lockups.
1060
1061config X86_UP_IOAPIC
1062 bool "IO-APIC support on uniprocessors"
1063 depends on X86_UP_APIC
1064 help
1065 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1066 SMP-capable replacement for PC-style interrupt controllers. Most
1067 SMP systems and many recent uniprocessor systems have one.
1068
1069 If you have a single-CPU system with an IO-APIC, you can say Y here
1070 to use it. If you say Y here even though your machine doesn't have
1071 an IO-APIC, then the kernel will still run with no slowdown at all.
1072
1073config X86_LOCAL_APIC
1074 def_bool y
1075 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1076 select IRQ_DOMAIN_HIERARCHY
1077 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1078
1079config X86_IO_APIC
1080 def_bool y
1081 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1082
1083config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1084 bool "Reroute for broken boot IRQs"
1085 depends on X86_IO_APIC
1086 help
1087 This option enables a workaround that fixes a source of
1088 spurious interrupts. This is recommended when threaded
1089 interrupt handling is used on systems where the generation of
1090 superfluous "boot interrupts" cannot be disabled.
1091
1092 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1093 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1094 kernel does during interrupt handling). On chipsets where this
1095 boot IRQ generation cannot be disabled, this workaround keeps
1096 the original IRQ line masked so that only the equivalent "boot
1097 IRQ" is delivered to the CPUs. The workaround also tells the
1098 kernel to set up the IRQ handler on the boot IRQ line. In this
1099 way only one interrupt is delivered to the kernel. Otherwise
1100 the spurious second interrupt may cause the kernel to bring
1101 down (vital) interrupt lines.
1102
1103 Only affects "broken" chipsets. Interrupt sharing may be
1104 increased on these systems.
1105
1106config X86_MCE
1107 bool "Machine Check / overheating reporting"
1108 select GENERIC_ALLOCATOR
1109 default y
1110 help
1111 Machine Check support allows the processor to notify the
1112 kernel if it detects a problem (e.g. overheating, data corruption).
1113 The action the kernel takes depends on the severity of the problem,
1114 ranging from warning messages to halting the machine.
1115
1116config X86_MCELOG_LEGACY
1117 bool "Support for deprecated /dev/mcelog character device"
1118 depends on X86_MCE
1119 help
1120 Enable support for /dev/mcelog which is needed by the old mcelog
1121 userspace logging daemon. Consider switching to the new generation
1122 rasdaemon solution.
1123
1124config X86_MCE_INTEL
1125 def_bool y
1126 prompt "Intel MCE features"
1127 depends on X86_MCE && X86_LOCAL_APIC
1128 help
1129 Additional support for intel specific MCE features such as
1130 the thermal monitor.
1131
1132config X86_MCE_AMD
1133 def_bool y
1134 prompt "AMD MCE features"
1135 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1136 help
1137 Additional support for AMD specific MCE features such as
1138 the DRAM Error Threshold.
1139
1140config X86_ANCIENT_MCE
1141 bool "Support for old Pentium 5 / WinChip machine checks"
1142 depends on X86_32 && X86_MCE
1143 help
1144 Include support for machine check handling on old Pentium 5 or WinChip
1145 systems. These typically need to be enabled explicitly on the command
1146 line.
1147
1148config X86_MCE_THRESHOLD
1149 depends on X86_MCE_AMD || X86_MCE_INTEL
1150 def_bool y
1151
1152config X86_MCE_INJECT
1153 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1154 tristate "Machine check injector support"
1155 help
1156 Provide support for injecting machine checks for testing purposes.
1157 If you don't know what a machine check is and you don't do kernel
1158 QA it is safe to say n.
1159
1160source "arch/x86/events/Kconfig"
1161
1162config X86_LEGACY_VM86
1163 bool "Legacy VM86 support"
1164 depends on X86_32
1165 help
1166 This option allows user programs to put the CPU into V8086
1167 mode, which is an 80286-era approximation of 16-bit real mode.
1168
1169 Some very old versions of X and/or vbetool require this option
1170 for user mode setting. Similarly, DOSEMU will use it if
1171 available to accelerate real mode DOS programs. However, any
1172 recent version of DOSEMU, X, or vbetool should be fully
1173 functional even without kernel VM86 support, as they will all
1174 fall back to software emulation. Nevertheless, if you are using
1175 a 16-bit DOS program where 16-bit performance matters, vm86
1176 mode might be faster than emulation and you might want to
1177 enable this option.
1178
1179 Note that any app that works on a 64-bit kernel is unlikely to
1180 need this option, as 64-bit kernels don't, and can't, support
1181 V8086 mode. This option is also unrelated to 16-bit protected
1182 mode and is not needed to run most 16-bit programs under Wine.
1183
1184 Enabling this option increases the complexity of the kernel
1185 and slows down exception handling a tiny bit.
1186
1187 If unsure, say N here.
1188
1189config VM86
1190 bool
1191 default X86_LEGACY_VM86
1192
1193config X86_16BIT
1194 bool "Enable support for 16-bit segments" if EXPERT
1195 default y
1196 depends on MODIFY_LDT_SYSCALL
1197 help
1198 This option is required by programs like Wine to run 16-bit
1199 protected mode legacy code on x86 processors. Disabling
1200 this option saves about 300 bytes on i386, or around 6K text
1201 plus 16K runtime memory on x86-64,
1202
1203config X86_ESPFIX32
1204 def_bool y
1205 depends on X86_16BIT && X86_32
1206
1207config X86_ESPFIX64
1208 def_bool y
1209 depends on X86_16BIT && X86_64
1210
1211config X86_VSYSCALL_EMULATION
1212 bool "Enable vsyscall emulation" if EXPERT
1213 default y
1214 depends on X86_64
1215 help
1216 This enables emulation of the legacy vsyscall page. Disabling
1217 it is roughly equivalent to booting with vsyscall=none, except
1218 that it will also disable the helpful warning if a program
1219 tries to use a vsyscall. With this option set to N, offending
1220 programs will just segfault, citing addresses of the form
1221 0xffffffffff600?00.
1222
1223 This option is required by many programs built before 2013, and
1224 care should be used even with newer programs if set to N.
1225
1226 Disabling this option saves about 7K of kernel size and
1227 possibly 4K of additional runtime pagetable memory.
1228
1229config X86_IOPL_IOPERM
1230 bool "IOPERM and IOPL Emulation"
1231 default y
1232 help
1233 This enables the ioperm() and iopl() syscalls which are necessary
1234 for legacy applications.
1235
1236 Legacy IOPL support is an overbroad mechanism which allows user
1237 space aside of accessing all 65536 I/O ports also to disable
1238 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1239 capabilities and permission from potentially active security
1240 modules.
1241
1242 The emulation restricts the functionality of the syscall to
1243 only allowing the full range I/O port access, but prevents the
1244 ability to disable interrupts from user space which would be
1245 granted if the hardware IOPL mechanism would be used.
1246
1247config TOSHIBA
1248 tristate "Toshiba Laptop support"
1249 depends on X86_32
1250 help
1251 This adds a driver to safely access the System Management Mode of
1252 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1253 not work on models with a Phoenix BIOS. The System Management Mode
1254 is used to set the BIOS and power saving options on Toshiba portables.
1255
1256 For information on utilities to make use of this driver see the
1257 Toshiba Linux utilities web site at:
1258 <http://www.buzzard.org.uk/toshiba/>.
1259
1260 Say Y if you intend to run this kernel on a Toshiba portable.
1261 Say N otherwise.
1262
1263config I8K
1264 tristate "Dell i8k legacy laptop support"
1265 select HWMON
1266 select SENSORS_DELL_SMM
1267 help
1268 This option enables legacy /proc/i8k userspace interface in hwmon
1269 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1270 temperature and allows controlling fan speeds of Dell laptops via
1271 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1272 it reports also power and hotkey status. For fan speed control is
1273 needed userspace package i8kutils.
1274
1275 Say Y if you intend to run this kernel on old Dell laptops or want to
1276 use userspace package i8kutils.
1277 Say N otherwise.
1278
1279config X86_REBOOTFIXUPS
1280 bool "Enable X86 board specific fixups for reboot"
1281 depends on X86_32
1282 help
1283 This enables chipset and/or board specific fixups to be done
1284 in order to get reboot to work correctly. This is only needed on
1285 some combinations of hardware and BIOS. The symptom, for which
1286 this config is intended, is when reboot ends with a stalled/hung
1287 system.
1288
1289 Currently, the only fixup is for the Geode machines using
1290 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1291
1292 Say Y if you want to enable the fixup. Currently, it's safe to
1293 enable this option even if you don't need it.
1294 Say N otherwise.
1295
1296config MICROCODE
1297 bool "CPU microcode loading support"
1298 default y
1299 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1300 help
1301 If you say Y here, you will be able to update the microcode on
1302 Intel and AMD processors. The Intel support is for the IA32 family,
1303 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1304 AMD support is for families 0x10 and later. You will obviously need
1305 the actual microcode binary data itself which is not shipped with
1306 the Linux kernel.
1307
1308 The preferred method to load microcode from a detached initrd is described
1309 in Documentation/x86/microcode.rst. For that you need to enable
1310 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1311 initrd for microcode blobs.
1312
1313 In addition, you can build the microcode into the kernel. For that you
1314 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1315 config option.
1316
1317config MICROCODE_INTEL
1318 bool "Intel microcode loading support"
1319 depends on MICROCODE
1320 default MICROCODE
1321 help
1322 This options enables microcode patch loading support for Intel
1323 processors.
1324
1325 For the current Intel microcode data package go to
1326 <https://downloadcenter.intel.com> and search for
1327 'Linux Processor Microcode Data File'.
1328
1329config MICROCODE_AMD
1330 bool "AMD microcode loading support"
1331 depends on MICROCODE
1332 help
1333 If you select this option, microcode patch loading support for AMD
1334 processors will be enabled.
1335
1336config MICROCODE_OLD_INTERFACE
1337 bool "Ancient loading interface (DEPRECATED)"
1338 default n
1339 depends on MICROCODE
1340 help
1341 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1342 which was used by userspace tools like iucode_tool and microcode.ctl.
1343 It is inadequate because it runs too late to be able to properly
1344 load microcode on a machine and it needs special tools. Instead, you
1345 should've switched to the early loading method with the initrd or
1346 builtin microcode by now: Documentation/x86/microcode.rst
1347
1348config X86_MSR
1349 tristate "/dev/cpu/*/msr - Model-specific register support"
1350 help
1351 This device gives privileged processes access to the x86
1352 Model-Specific Registers (MSRs). It is a character device with
1353 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1354 MSR accesses are directed to a specific CPU on multi-processor
1355 systems.
1356
1357config X86_CPUID
1358 tristate "/dev/cpu/*/cpuid - CPU information support"
1359 help
1360 This device gives processes access to the x86 CPUID instruction to
1361 be executed on a specific processor. It is a character device
1362 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1363 /dev/cpu/31/cpuid.
1364
1365choice
1366 prompt "High Memory Support"
1367 default HIGHMEM4G
1368 depends on X86_32
1369
1370config NOHIGHMEM
1371 bool "off"
1372 help
1373 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1374 However, the address space of 32-bit x86 processors is only 4
1375 Gigabytes large. That means that, if you have a large amount of
1376 physical memory, not all of it can be "permanently mapped" by the
1377 kernel. The physical memory that's not permanently mapped is called
1378 "high memory".
1379
1380 If you are compiling a kernel which will never run on a machine with
1381 more than 1 Gigabyte total physical RAM, answer "off" here (default
1382 choice and suitable for most users). This will result in a "3GB/1GB"
1383 split: 3GB are mapped so that each process sees a 3GB virtual memory
1384 space and the remaining part of the 4GB virtual memory space is used
1385 by the kernel to permanently map as much physical memory as
1386 possible.
1387
1388 If the machine has between 1 and 4 Gigabytes physical RAM, then
1389 answer "4GB" here.
1390
1391 If more than 4 Gigabytes is used then answer "64GB" here. This
1392 selection turns Intel PAE (Physical Address Extension) mode on.
1393 PAE implements 3-level paging on IA32 processors. PAE is fully
1394 supported by Linux, PAE mode is implemented on all recent Intel
1395 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1396 then the kernel will not boot on CPUs that don't support PAE!
1397
1398 The actual amount of total physical memory will either be
1399 auto detected or can be forced by using a kernel command line option
1400 such as "mem=256M". (Try "man bootparam" or see the documentation of
1401 your boot loader (lilo or loadlin) about how to pass options to the
1402 kernel at boot time.)
1403
1404 If unsure, say "off".
1405
1406config HIGHMEM4G
1407 bool "4GB"
1408 help
1409 Select this if you have a 32-bit processor and between 1 and 4
1410 gigabytes of physical RAM.
1411
1412config HIGHMEM64G
1413 bool "64GB"
1414 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1415 select X86_PAE
1416 help
1417 Select this if you have a 32-bit processor and more than 4
1418 gigabytes of physical RAM.
1419
1420endchoice
1421
1422choice
1423 prompt "Memory split" if EXPERT
1424 default VMSPLIT_3G
1425 depends on X86_32
1426 help
1427 Select the desired split between kernel and user memory.
1428
1429 If the address range available to the kernel is less than the
1430 physical memory installed, the remaining memory will be available
1431 as "high memory". Accessing high memory is a little more costly
1432 than low memory, as it needs to be mapped into the kernel first.
1433 Note that increasing the kernel address space limits the range
1434 available to user programs, making the address space there
1435 tighter. Selecting anything other than the default 3G/1G split
1436 will also likely make your kernel incompatible with binary-only
1437 kernel modules.
1438
1439 If you are not absolutely sure what you are doing, leave this
1440 option alone!
1441
1442 config VMSPLIT_3G
1443 bool "3G/1G user/kernel split"
1444 config VMSPLIT_3G_OPT
1445 depends on !X86_PAE
1446 bool "3G/1G user/kernel split (for full 1G low memory)"
1447 config VMSPLIT_2G
1448 bool "2G/2G user/kernel split"
1449 config VMSPLIT_2G_OPT
1450 depends on !X86_PAE
1451 bool "2G/2G user/kernel split (for full 2G low memory)"
1452 config VMSPLIT_1G
1453 bool "1G/3G user/kernel split"
1454endchoice
1455
1456config PAGE_OFFSET
1457 hex
1458 default 0xB0000000 if VMSPLIT_3G_OPT
1459 default 0x80000000 if VMSPLIT_2G
1460 default 0x78000000 if VMSPLIT_2G_OPT
1461 default 0x40000000 if VMSPLIT_1G
1462 default 0xC0000000
1463 depends on X86_32
1464
1465config HIGHMEM
1466 def_bool y
1467 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1468
1469config X86_PAE
1470 bool "PAE (Physical Address Extension) Support"
1471 depends on X86_32 && !HIGHMEM4G
1472 select PHYS_ADDR_T_64BIT
1473 select SWIOTLB
1474 help
1475 PAE is required for NX support, and furthermore enables
1476 larger swapspace support for non-overcommit purposes. It
1477 has the cost of more pagetable lookup overhead, and also
1478 consumes more pagetable space per process.
1479
1480config X86_5LEVEL
1481 bool "Enable 5-level page tables support"
1482 default y
1483 select DYNAMIC_MEMORY_LAYOUT
1484 select SPARSEMEM_VMEMMAP
1485 depends on X86_64
1486 help
1487 5-level paging enables access to larger address space:
1488 upto 128 PiB of virtual address space and 4 PiB of
1489 physical address space.
1490
1491 It will be supported by future Intel CPUs.
1492
1493 A kernel with the option enabled can be booted on machines that
1494 support 4- or 5-level paging.
1495
1496 See Documentation/x86/x86_64/5level-paging.rst for more
1497 information.
1498
1499 Say N if unsure.
1500
1501config X86_DIRECT_GBPAGES
1502 def_bool y
1503 depends on X86_64
1504 help
1505 Certain kernel features effectively disable kernel
1506 linear 1 GB mappings (even if the CPU otherwise
1507 supports them), so don't confuse the user by printing
1508 that we have them enabled.
1509
1510config X86_CPA_STATISTICS
1511 bool "Enable statistic for Change Page Attribute"
1512 depends on DEBUG_FS
1513 help
1514 Expose statistics about the Change Page Attribute mechanism, which
1515 helps to determine the effectiveness of preserving large and huge
1516 page mappings when mapping protections are changed.
1517
1518config AMD_MEM_ENCRYPT
1519 bool "AMD Secure Memory Encryption (SME) support"
1520 depends on X86_64 && CPU_SUP_AMD
1521 select DMA_COHERENT_POOL
1522 select DYNAMIC_PHYSICAL_MASK
1523 select ARCH_USE_MEMREMAP_PROT
1524 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1525 select INSTRUCTION_DECODER
1526 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1527 help
1528 Say yes to enable support for the encryption of system memory.
1529 This requires an AMD processor that supports Secure Memory
1530 Encryption (SME).
1531
1532config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1533 bool "Activate AMD Secure Memory Encryption (SME) by default"
1534 default y
1535 depends on AMD_MEM_ENCRYPT
1536 help
1537 Say yes to have system memory encrypted by default if running on
1538 an AMD processor that supports Secure Memory Encryption (SME).
1539
1540 If set to Y, then the encryption of system memory can be
1541 deactivated with the mem_encrypt=off command line option.
1542
1543 If set to N, then the encryption of system memory can be
1544 activated with the mem_encrypt=on command line option.
1545
1546# Common NUMA Features
1547config NUMA
1548 bool "NUMA Memory Allocation and Scheduler Support"
1549 depends on SMP
1550 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1551 default y if X86_BIGSMP
1552 help
1553 Enable NUMA (Non-Uniform Memory Access) support.
1554
1555 The kernel will try to allocate memory used by a CPU on the
1556 local memory controller of the CPU and add some more
1557 NUMA awareness to the kernel.
1558
1559 For 64-bit this is recommended if the system is Intel Core i7
1560 (or later), AMD Opteron, or EM64T NUMA.
1561
1562 For 32-bit this is only needed if you boot a 32-bit
1563 kernel on a 64-bit NUMA platform.
1564
1565 Otherwise, you should say N.
1566
1567config AMD_NUMA
1568 def_bool y
1569 prompt "Old style AMD Opteron NUMA detection"
1570 depends on X86_64 && NUMA && PCI
1571 help
1572 Enable AMD NUMA node topology detection. You should say Y here if
1573 you have a multi processor AMD system. This uses an old method to
1574 read the NUMA configuration directly from the builtin Northbridge
1575 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1576 which also takes priority if both are compiled in.
1577
1578config X86_64_ACPI_NUMA
1579 def_bool y
1580 prompt "ACPI NUMA detection"
1581 depends on X86_64 && NUMA && ACPI && PCI
1582 select ACPI_NUMA
1583 help
1584 Enable ACPI SRAT based node topology detection.
1585
1586config NUMA_EMU
1587 bool "NUMA emulation"
1588 depends on NUMA
1589 help
1590 Enable NUMA emulation. A flat machine will be split
1591 into virtual nodes when booted with "numa=fake=N", where N is the
1592 number of nodes. This is only useful for debugging.
1593
1594config NODES_SHIFT
1595 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1596 range 1 10
1597 default "10" if MAXSMP
1598 default "6" if X86_64
1599 default "3"
1600 depends on NEED_MULTIPLE_NODES
1601 help
1602 Specify the maximum number of NUMA Nodes available on the target
1603 system. Increases memory reserved to accommodate various tables.
1604
1605config ARCH_FLATMEM_ENABLE
1606 def_bool y
1607 depends on X86_32 && !NUMA
1608
1609config ARCH_SPARSEMEM_ENABLE
1610 def_bool y
1611 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1612 select SPARSEMEM_STATIC if X86_32
1613 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1614
1615config ARCH_SPARSEMEM_DEFAULT
1616 def_bool X86_64 || (NUMA && X86_32)
1617
1618config ARCH_SELECT_MEMORY_MODEL
1619 def_bool y
1620 depends on ARCH_SPARSEMEM_ENABLE
1621
1622config ARCH_MEMORY_PROBE
1623 bool "Enable sysfs memory/probe interface"
1624 depends on X86_64 && MEMORY_HOTPLUG
1625 help
1626 This option enables a sysfs memory/probe interface for testing.
1627 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1628 If you are unsure how to answer this question, answer N.
1629
1630config ARCH_PROC_KCORE_TEXT
1631 def_bool y
1632 depends on X86_64 && PROC_KCORE
1633
1634config ILLEGAL_POINTER_VALUE
1635 hex
1636 default 0 if X86_32
1637 default 0xdead000000000000 if X86_64
1638
1639config X86_PMEM_LEGACY_DEVICE
1640 bool
1641
1642config X86_PMEM_LEGACY
1643 tristate "Support non-standard NVDIMMs and ADR protected memory"
1644 depends on PHYS_ADDR_T_64BIT
1645 depends on BLK_DEV
1646 select X86_PMEM_LEGACY_DEVICE
1647 select NUMA_KEEP_MEMINFO if NUMA
1648 select LIBNVDIMM
1649 help
1650 Treat memory marked using the non-standard e820 type of 12 as used
1651 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1652 The kernel will offer these regions to the 'pmem' driver so
1653 they can be used for persistent storage.
1654
1655 Say Y if unsure.
1656
1657config HIGHPTE
1658 bool "Allocate 3rd-level pagetables from highmem"
1659 depends on HIGHMEM
1660 help
1661 The VM uses one page table entry for each page of physical memory.
1662 For systems with a lot of RAM, this can be wasteful of precious
1663 low memory. Setting this option will put user-space page table
1664 entries in high memory.
1665
1666config X86_CHECK_BIOS_CORRUPTION
1667 bool "Check for low memory corruption"
1668 help
1669 Periodically check for memory corruption in low memory, which
1670 is suspected to be caused by BIOS. Even when enabled in the
1671 configuration, it is disabled at runtime. Enable it by
1672 setting "memory_corruption_check=1" on the kernel command
1673 line. By default it scans the low 64k of memory every 60
1674 seconds; see the memory_corruption_check_size and
1675 memory_corruption_check_period parameters in
1676 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1677
1678 When enabled with the default parameters, this option has
1679 almost no overhead, as it reserves a relatively small amount
1680 of memory and scans it infrequently. It both detects corruption
1681 and prevents it from affecting the running system.
1682
1683 It is, however, intended as a diagnostic tool; if repeatable
1684 BIOS-originated corruption always affects the same memory,
1685 you can use memmap= to prevent the kernel from using that
1686 memory.
1687
1688config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1689 bool "Set the default setting of memory_corruption_check"
1690 depends on X86_CHECK_BIOS_CORRUPTION
1691 default y
1692 help
1693 Set whether the default state of memory_corruption_check is
1694 on or off.
1695
1696config X86_RESERVE_LOW
1697 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1698 default 64
1699 range 4 640
1700 help
1701 Specify the amount of low memory to reserve for the BIOS.
1702
1703 The first page contains BIOS data structures that the kernel
1704 must not use, so that page must always be reserved.
1705
1706 By default we reserve the first 64K of physical RAM, as a
1707 number of BIOSes are known to corrupt that memory range
1708 during events such as suspend/resume or monitor cable
1709 insertion, so it must not be used by the kernel.
1710
1711 You can set this to 4 if you are absolutely sure that you
1712 trust the BIOS to get all its memory reservations and usages
1713 right. If you know your BIOS have problems beyond the
1714 default 64K area, you can set this to 640 to avoid using the
1715 entire low memory range.
1716
1717 If you have doubts about the BIOS (e.g. suspend/resume does
1718 not work or there's kernel crashes after certain hardware
1719 hotplug events) then you might want to enable
1720 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1721 typical corruption patterns.
1722
1723 Leave this to the default value of 64 if you are unsure.
1724
1725config MATH_EMULATION
1726 bool
1727 depends on MODIFY_LDT_SYSCALL
1728 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1729 help
1730 Linux can emulate a math coprocessor (used for floating point
1731 operations) if you don't have one. 486DX and Pentium processors have
1732 a math coprocessor built in, 486SX and 386 do not, unless you added
1733 a 487DX or 387, respectively. (The messages during boot time can
1734 give you some hints here ["man dmesg"].) Everyone needs either a
1735 coprocessor or this emulation.
1736
1737 If you don't have a math coprocessor, you need to say Y here; if you
1738 say Y here even though you have a coprocessor, the coprocessor will
1739 be used nevertheless. (This behavior can be changed with the kernel
1740 command line option "no387", which comes handy if your coprocessor
1741 is broken. Try "man bootparam" or see the documentation of your boot
1742 loader (lilo or loadlin) about how to pass options to the kernel at
1743 boot time.) This means that it is a good idea to say Y here if you
1744 intend to use this kernel on different machines.
1745
1746 More information about the internals of the Linux math coprocessor
1747 emulation can be found in <file:arch/x86/math-emu/README>.
1748
1749 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1750 kernel, it won't hurt.
1751
1752config MTRR
1753 def_bool y
1754 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1755 help
1756 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1757 the Memory Type Range Registers (MTRRs) may be used to control
1758 processor access to memory ranges. This is most useful if you have
1759 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1760 allows bus write transfers to be combined into a larger transfer
1761 before bursting over the PCI/AGP bus. This can increase performance
1762 of image write operations 2.5 times or more. Saying Y here creates a
1763 /proc/mtrr file which may be used to manipulate your processor's
1764 MTRRs. Typically the X server should use this.
1765
1766 This code has a reasonably generic interface so that similar
1767 control registers on other processors can be easily supported
1768 as well:
1769
1770 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1771 Registers (ARRs) which provide a similar functionality to MTRRs. For
1772 these, the ARRs are used to emulate the MTRRs.
1773 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1774 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1775 write-combining. All of these processors are supported by this code
1776 and it makes sense to say Y here if you have one of them.
1777
1778 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1779 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1780 can lead to all sorts of problems, so it's good to say Y here.
1781
1782 You can safely say Y even if your machine doesn't have MTRRs, you'll
1783 just add about 9 KB to your kernel.
1784
1785 See <file:Documentation/x86/mtrr.rst> for more information.
1786
1787config MTRR_SANITIZER
1788 def_bool y
1789 prompt "MTRR cleanup support"
1790 depends on MTRR
1791 help
1792 Convert MTRR layout from continuous to discrete, so X drivers can
1793 add writeback entries.
1794
1795 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1796 The largest mtrr entry size for a continuous block can be set with
1797 mtrr_chunk_size.
1798
1799 If unsure, say Y.
1800
1801config MTRR_SANITIZER_ENABLE_DEFAULT
1802 int "MTRR cleanup enable value (0-1)"
1803 range 0 1
1804 default "0"
1805 depends on MTRR_SANITIZER
1806 help
1807 Enable mtrr cleanup default value
1808
1809config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1810 int "MTRR cleanup spare reg num (0-7)"
1811 range 0 7
1812 default "1"
1813 depends on MTRR_SANITIZER
1814 help
1815 mtrr cleanup spare entries default, it can be changed via
1816 mtrr_spare_reg_nr=N on the kernel command line.
1817
1818config X86_PAT
1819 def_bool y
1820 prompt "x86 PAT support" if EXPERT
1821 depends on MTRR
1822 help
1823 Use PAT attributes to setup page level cache control.
1824
1825 PATs are the modern equivalents of MTRRs and are much more
1826 flexible than MTRRs.
1827
1828 Say N here if you see bootup problems (boot crash, boot hang,
1829 spontaneous reboots) or a non-working video driver.
1830
1831 If unsure, say Y.
1832
1833config ARCH_USES_PG_UNCACHED
1834 def_bool y
1835 depends on X86_PAT
1836
1837config ARCH_RANDOM
1838 def_bool y
1839 prompt "x86 architectural random number generator" if EXPERT
1840 help
1841 Enable the x86 architectural RDRAND instruction
1842 (Intel Bull Mountain technology) to generate random numbers.
1843 If supported, this is a high bandwidth, cryptographically
1844 secure hardware random number generator.
1845
1846config X86_SMAP
1847 def_bool y
1848 prompt "Supervisor Mode Access Prevention" if EXPERT
1849 help
1850 Supervisor Mode Access Prevention (SMAP) is a security
1851 feature in newer Intel processors. There is a small
1852 performance cost if this enabled and turned on; there is
1853 also a small increase in the kernel size if this is enabled.
1854
1855 If unsure, say Y.
1856
1857config X86_UMIP
1858 def_bool y
1859 prompt "User Mode Instruction Prevention" if EXPERT
1860 help
1861 User Mode Instruction Prevention (UMIP) is a security feature in
1862 some x86 processors. If enabled, a general protection fault is
1863 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1864 executed in user mode. These instructions unnecessarily expose
1865 information about the hardware state.
1866
1867 The vast majority of applications do not use these instructions.
1868 For the very few that do, software emulation is provided in
1869 specific cases in protected and virtual-8086 modes. Emulated
1870 results are dummy.
1871
1872config X86_INTEL_MEMORY_PROTECTION_KEYS
1873 prompt "Memory Protection Keys"
1874 def_bool y
1875 # Note: only available in 64-bit mode
1876 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1877 select ARCH_USES_HIGH_VMA_FLAGS
1878 select ARCH_HAS_PKEYS
1879 help
1880 Memory Protection Keys provides a mechanism for enforcing
1881 page-based protections, but without requiring modification of the
1882 page tables when an application changes protection domains.
1883
1884 For details, see Documentation/core-api/protection-keys.rst
1885
1886 If unsure, say y.
1887
1888choice
1889 prompt "TSX enable mode"
1890 depends on CPU_SUP_INTEL
1891 default X86_INTEL_TSX_MODE_OFF
1892 help
1893 Intel's TSX (Transactional Synchronization Extensions) feature
1894 allows to optimize locking protocols through lock elision which
1895 can lead to a noticeable performance boost.
1896
1897 On the other hand it has been shown that TSX can be exploited
1898 to form side channel attacks (e.g. TAA) and chances are there
1899 will be more of those attacks discovered in the future.
1900
1901 Therefore TSX is not enabled by default (aka tsx=off). An admin
1902 might override this decision by tsx=on the command line parameter.
1903 Even with TSX enabled, the kernel will attempt to enable the best
1904 possible TAA mitigation setting depending on the microcode available
1905 for the particular machine.
1906
1907 This option allows to set the default tsx mode between tsx=on, =off
1908 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1909 details.
1910
1911 Say off if not sure, auto if TSX is in use but it should be used on safe
1912 platforms or on if TSX is in use and the security aspect of tsx is not
1913 relevant.
1914
1915config X86_INTEL_TSX_MODE_OFF
1916 bool "off"
1917 help
1918 TSX is disabled if possible - equals to tsx=off command line parameter.
1919
1920config X86_INTEL_TSX_MODE_ON
1921 bool "on"
1922 help
1923 TSX is always enabled on TSX capable HW - equals the tsx=on command
1924 line parameter.
1925
1926config X86_INTEL_TSX_MODE_AUTO
1927 bool "auto"
1928 help
1929 TSX is enabled on TSX capable HW that is believed to be safe against
1930 side channel attacks- equals the tsx=auto command line parameter.
1931endchoice
1932
1933config X86_SGX
1934 bool "Software Guard eXtensions (SGX)"
1935 depends on X86_64 && CPU_SUP_INTEL
1936 depends on CRYPTO=y
1937 depends on CRYPTO_SHA256=y
1938 select SRCU
1939 select MMU_NOTIFIER
1940 select NUMA_KEEP_MEMINFO if NUMA
1941 help
1942 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1943 that can be used by applications to set aside private regions of code
1944 and data, referred to as enclaves. An enclave's private memory can
1945 only be accessed by code running within the enclave. Accesses from
1946 outside the enclave, including other enclaves, are disallowed by
1947 hardware.
1948
1949 If unsure, say N.
1950
1951config EFI
1952 bool "EFI runtime service support"
1953 depends on ACPI
1954 select UCS2_STRING
1955 select EFI_RUNTIME_WRAPPERS
1956 help
1957 This enables the kernel to use EFI runtime services that are
1958 available (such as the EFI variable services).
1959
1960 This option is only useful on systems that have EFI firmware.
1961 In addition, you should use the latest ELILO loader available
1962 at <http://elilo.sourceforge.net> in order to take advantage
1963 of EFI runtime services. However, even with this option, the
1964 resultant kernel should continue to boot on existing non-EFI
1965 platforms.
1966
1967config EFI_STUB
1968 bool "EFI stub support"
1969 depends on EFI && !X86_USE_3DNOW
1970 depends on $(cc-option,-mabi=ms) || X86_32
1971 select RELOCATABLE
1972 help
1973 This kernel feature allows a bzImage to be loaded directly
1974 by EFI firmware without the use of a bootloader.
1975
1976 See Documentation/admin-guide/efi-stub.rst for more information.
1977
1978config EFI_MIXED
1979 bool "EFI mixed-mode support"
1980 depends on EFI_STUB && X86_64
1981 help
1982 Enabling this feature allows a 64-bit kernel to be booted
1983 on a 32-bit firmware, provided that your CPU supports 64-bit
1984 mode.
1985
1986 Note that it is not possible to boot a mixed-mode enabled
1987 kernel via the EFI boot stub - a bootloader that supports
1988 the EFI handover protocol must be used.
1989
1990 If unsure, say N.
1991
1992source "kernel/Kconfig.hz"
1993
1994config KEXEC
1995 bool "kexec system call"
1996 select KEXEC_CORE
1997 help
1998 kexec is a system call that implements the ability to shutdown your
1999 current kernel, and to start another kernel. It is like a reboot
2000 but it is independent of the system firmware. And like a reboot
2001 you can start any kernel with it, not just Linux.
2002
2003 The name comes from the similarity to the exec system call.
2004
2005 It is an ongoing process to be certain the hardware in a machine
2006 is properly shutdown, so do not be surprised if this code does not
2007 initially work for you. As of this writing the exact hardware
2008 interface is strongly in flux, so no good recommendation can be
2009 made.
2010
2011config KEXEC_FILE
2012 bool "kexec file based system call"
2013 select KEXEC_CORE
2014 select BUILD_BIN2C
2015 depends on X86_64
2016 depends on CRYPTO=y
2017 depends on CRYPTO_SHA256=y
2018 help
2019 This is new version of kexec system call. This system call is
2020 file based and takes file descriptors as system call argument
2021 for kernel and initramfs as opposed to list of segments as
2022 accepted by previous system call.
2023
2024config ARCH_HAS_KEXEC_PURGATORY
2025 def_bool KEXEC_FILE
2026
2027config KEXEC_SIG
2028 bool "Verify kernel signature during kexec_file_load() syscall"
2029 depends on KEXEC_FILE
2030 help
2031
2032 This option makes the kexec_file_load() syscall check for a valid
2033 signature of the kernel image. The image can still be loaded without
2034 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2035 there's a signature that we can check, then it must be valid.
2036
2037 In addition to this option, you need to enable signature
2038 verification for the corresponding kernel image type being
2039 loaded in order for this to work.
2040
2041config KEXEC_SIG_FORCE
2042 bool "Require a valid signature in kexec_file_load() syscall"
2043 depends on KEXEC_SIG
2044 help
2045 This option makes kernel signature verification mandatory for
2046 the kexec_file_load() syscall.
2047
2048config KEXEC_BZIMAGE_VERIFY_SIG
2049 bool "Enable bzImage signature verification support"
2050 depends on KEXEC_SIG
2051 depends on SIGNED_PE_FILE_VERIFICATION
2052 select SYSTEM_TRUSTED_KEYRING
2053 help
2054 Enable bzImage signature verification support.
2055
2056config CRASH_DUMP
2057 bool "kernel crash dumps"
2058 depends on X86_64 || (X86_32 && HIGHMEM)
2059 help
2060 Generate crash dump after being started by kexec.
2061 This should be normally only set in special crash dump kernels
2062 which are loaded in the main kernel with kexec-tools into
2063 a specially reserved region and then later executed after
2064 a crash by kdump/kexec. The crash dump kernel must be compiled
2065 to a memory address not used by the main kernel or BIOS using
2066 PHYSICAL_START, or it must be built as a relocatable image
2067 (CONFIG_RELOCATABLE=y).
2068 For more details see Documentation/admin-guide/kdump/kdump.rst
2069
2070config KEXEC_JUMP
2071 bool "kexec jump"
2072 depends on KEXEC && HIBERNATION
2073 help
2074 Jump between original kernel and kexeced kernel and invoke
2075 code in physical address mode via KEXEC
2076
2077config PHYSICAL_START
2078 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2079 default "0x1000000"
2080 help
2081 This gives the physical address where the kernel is loaded.
2082
2083 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2084 bzImage will decompress itself to above physical address and
2085 run from there. Otherwise, bzImage will run from the address where
2086 it has been loaded by the boot loader and will ignore above physical
2087 address.
2088
2089 In normal kdump cases one does not have to set/change this option
2090 as now bzImage can be compiled as a completely relocatable image
2091 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2092 address. This option is mainly useful for the folks who don't want
2093 to use a bzImage for capturing the crash dump and want to use a
2094 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2095 to be specifically compiled to run from a specific memory area
2096 (normally a reserved region) and this option comes handy.
2097
2098 So if you are using bzImage for capturing the crash dump,
2099 leave the value here unchanged to 0x1000000 and set
2100 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2101 for capturing the crash dump change this value to start of
2102 the reserved region. In other words, it can be set based on
2103 the "X" value as specified in the "crashkernel=YM@XM"
2104 command line boot parameter passed to the panic-ed
2105 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2106 for more details about crash dumps.
2107
2108 Usage of bzImage for capturing the crash dump is recommended as
2109 one does not have to build two kernels. Same kernel can be used
2110 as production kernel and capture kernel. Above option should have
2111 gone away after relocatable bzImage support is introduced. But it
2112 is present because there are users out there who continue to use
2113 vmlinux for dump capture. This option should go away down the
2114 line.
2115
2116 Don't change this unless you know what you are doing.
2117
2118config RELOCATABLE
2119 bool "Build a relocatable kernel"
2120 default y
2121 help
2122 This builds a kernel image that retains relocation information
2123 so it can be loaded someplace besides the default 1MB.
2124 The relocations tend to make the kernel binary about 10% larger,
2125 but are discarded at runtime.
2126
2127 One use is for the kexec on panic case where the recovery kernel
2128 must live at a different physical address than the primary
2129 kernel.
2130
2131 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2132 it has been loaded at and the compile time physical address
2133 (CONFIG_PHYSICAL_START) is used as the minimum location.
2134
2135config RANDOMIZE_BASE
2136 bool "Randomize the address of the kernel image (KASLR)"
2137 depends on RELOCATABLE
2138 default y
2139 help
2140 In support of Kernel Address Space Layout Randomization (KASLR),
2141 this randomizes the physical address at which the kernel image
2142 is decompressed and the virtual address where the kernel
2143 image is mapped, as a security feature that deters exploit
2144 attempts relying on knowledge of the location of kernel
2145 code internals.
2146
2147 On 64-bit, the kernel physical and virtual addresses are
2148 randomized separately. The physical address will be anywhere
2149 between 16MB and the top of physical memory (up to 64TB). The
2150 virtual address will be randomized from 16MB up to 1GB (9 bits
2151 of entropy). Note that this also reduces the memory space
2152 available to kernel modules from 1.5GB to 1GB.
2153
2154 On 32-bit, the kernel physical and virtual addresses are
2155 randomized together. They will be randomized from 16MB up to
2156 512MB (8 bits of entropy).
2157
2158 Entropy is generated using the RDRAND instruction if it is
2159 supported. If RDTSC is supported, its value is mixed into
2160 the entropy pool as well. If neither RDRAND nor RDTSC are
2161 supported, then entropy is read from the i8254 timer. The
2162 usable entropy is limited by the kernel being built using
2163 2GB addressing, and that PHYSICAL_ALIGN must be at a
2164 minimum of 2MB. As a result, only 10 bits of entropy are
2165 theoretically possible, but the implementations are further
2166 limited due to memory layouts.
2167
2168 If unsure, say Y.
2169
2170# Relocation on x86 needs some additional build support
2171config X86_NEED_RELOCS
2172 def_bool y
2173 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2174
2175config PHYSICAL_ALIGN
2176 hex "Alignment value to which kernel should be aligned"
2177 default "0x200000"
2178 range 0x2000 0x1000000 if X86_32
2179 range 0x200000 0x1000000 if X86_64
2180 help
2181 This value puts the alignment restrictions on physical address
2182 where kernel is loaded and run from. Kernel is compiled for an
2183 address which meets above alignment restriction.
2184
2185 If bootloader loads the kernel at a non-aligned address and
2186 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2187 address aligned to above value and run from there.
2188
2189 If bootloader loads the kernel at a non-aligned address and
2190 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2191 load address and decompress itself to the address it has been
2192 compiled for and run from there. The address for which kernel is
2193 compiled already meets above alignment restrictions. Hence the
2194 end result is that kernel runs from a physical address meeting
2195 above alignment restrictions.
2196
2197 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2198 this value must be a multiple of 0x200000.
2199
2200 Don't change this unless you know what you are doing.
2201
2202config DYNAMIC_MEMORY_LAYOUT
2203 bool
2204 help
2205 This option makes base addresses of vmalloc and vmemmap as well as
2206 __PAGE_OFFSET movable during boot.
2207
2208config RANDOMIZE_MEMORY
2209 bool "Randomize the kernel memory sections"
2210 depends on X86_64
2211 depends on RANDOMIZE_BASE
2212 select DYNAMIC_MEMORY_LAYOUT
2213 default RANDOMIZE_BASE
2214 help
2215 Randomizes the base virtual address of kernel memory sections
2216 (physical memory mapping, vmalloc & vmemmap). This security feature
2217 makes exploits relying on predictable memory locations less reliable.
2218
2219 The order of allocations remains unchanged. Entropy is generated in
2220 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2221 configuration have in average 30,000 different possible virtual
2222 addresses for each memory section.
2223
2224 If unsure, say Y.
2225
2226config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2227 hex "Physical memory mapping padding" if EXPERT
2228 depends on RANDOMIZE_MEMORY
2229 default "0xa" if MEMORY_HOTPLUG
2230 default "0x0"
2231 range 0x1 0x40 if MEMORY_HOTPLUG
2232 range 0x0 0x40
2233 help
2234 Define the padding in terabytes added to the existing physical
2235 memory size during kernel memory randomization. It is useful
2236 for memory hotplug support but reduces the entropy available for
2237 address randomization.
2238
2239 If unsure, leave at the default value.
2240
2241config HOTPLUG_CPU
2242 def_bool y
2243 depends on SMP
2244
2245config BOOTPARAM_HOTPLUG_CPU0
2246 bool "Set default setting of cpu0_hotpluggable"
2247 depends on HOTPLUG_CPU
2248 help
2249 Set whether default state of cpu0_hotpluggable is on or off.
2250
2251 Say Y here to enable CPU0 hotplug by default. If this switch
2252 is turned on, there is no need to give cpu0_hotplug kernel
2253 parameter and the CPU0 hotplug feature is enabled by default.
2254
2255 Please note: there are two known CPU0 dependencies if you want
2256 to enable the CPU0 hotplug feature either by this switch or by
2257 cpu0_hotplug kernel parameter.
2258
2259 First, resume from hibernate or suspend always starts from CPU0.
2260 So hibernate and suspend are prevented if CPU0 is offline.
2261
2262 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2263 offline if any interrupt can not migrate out of CPU0. There may
2264 be other CPU0 dependencies.
2265
2266 Please make sure the dependencies are under your control before
2267 you enable this feature.
2268
2269 Say N if you don't want to enable CPU0 hotplug feature by default.
2270 You still can enable the CPU0 hotplug feature at boot by kernel
2271 parameter cpu0_hotplug.
2272
2273config DEBUG_HOTPLUG_CPU0
2274 def_bool n
2275 prompt "Debug CPU0 hotplug"
2276 depends on HOTPLUG_CPU
2277 help
2278 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2279 soon as possible and boots up userspace with CPU0 offlined. User
2280 can online CPU0 back after boot time.
2281
2282 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2283 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2284 compilation or giving cpu0_hotplug kernel parameter at boot.
2285
2286 If unsure, say N.
2287
2288config COMPAT_VDSO
2289 def_bool n
2290 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2291 depends on COMPAT_32
2292 help
2293 Certain buggy versions of glibc will crash if they are
2294 presented with a 32-bit vDSO that is not mapped at the address
2295 indicated in its segment table.
2296
2297 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2298 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2299 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2300 the only released version with the bug, but OpenSUSE 9
2301 contains a buggy "glibc 2.3.2".
2302
2303 The symptom of the bug is that everything crashes on startup, saying:
2304 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2305
2306 Saying Y here changes the default value of the vdso32 boot
2307 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2308 This works around the glibc bug but hurts performance.
2309
2310 If unsure, say N: if you are compiling your own kernel, you
2311 are unlikely to be using a buggy version of glibc.
2312
2313choice
2314 prompt "vsyscall table for legacy applications"
2315 depends on X86_64
2316 default LEGACY_VSYSCALL_XONLY
2317 help
2318 Legacy user code that does not know how to find the vDSO expects
2319 to be able to issue three syscalls by calling fixed addresses in
2320 kernel space. Since this location is not randomized with ASLR,
2321 it can be used to assist security vulnerability exploitation.
2322
2323 This setting can be changed at boot time via the kernel command
2324 line parameter vsyscall=[emulate|xonly|none].
2325
2326 On a system with recent enough glibc (2.14 or newer) and no
2327 static binaries, you can say None without a performance penalty
2328 to improve security.
2329
2330 If unsure, select "Emulate execution only".
2331
2332 config LEGACY_VSYSCALL_EMULATE
2333 bool "Full emulation"
2334 help
2335 The kernel traps and emulates calls into the fixed vsyscall
2336 address mapping. This makes the mapping non-executable, but
2337 it still contains readable known contents, which could be
2338 used in certain rare security vulnerability exploits. This
2339 configuration is recommended when using legacy userspace
2340 that still uses vsyscalls along with legacy binary
2341 instrumentation tools that require code to be readable.
2342
2343 An example of this type of legacy userspace is running
2344 Pin on an old binary that still uses vsyscalls.
2345
2346 config LEGACY_VSYSCALL_XONLY
2347 bool "Emulate execution only"
2348 help
2349 The kernel traps and emulates calls into the fixed vsyscall
2350 address mapping and does not allow reads. This
2351 configuration is recommended when userspace might use the
2352 legacy vsyscall area but support for legacy binary
2353 instrumentation of legacy code is not needed. It mitigates
2354 certain uses of the vsyscall area as an ASLR-bypassing
2355 buffer.
2356
2357 config LEGACY_VSYSCALL_NONE
2358 bool "None"
2359 help
2360 There will be no vsyscall mapping at all. This will
2361 eliminate any risk of ASLR bypass due to the vsyscall
2362 fixed address mapping. Attempts to use the vsyscalls
2363 will be reported to dmesg, so that either old or
2364 malicious userspace programs can be identified.
2365
2366endchoice
2367
2368config CMDLINE_BOOL
2369 bool "Built-in kernel command line"
2370 help
2371 Allow for specifying boot arguments to the kernel at
2372 build time. On some systems (e.g. embedded ones), it is
2373 necessary or convenient to provide some or all of the
2374 kernel boot arguments with the kernel itself (that is,
2375 to not rely on the boot loader to provide them.)
2376
2377 To compile command line arguments into the kernel,
2378 set this option to 'Y', then fill in the
2379 boot arguments in CONFIG_CMDLINE.
2380
2381 Systems with fully functional boot loaders (i.e. non-embedded)
2382 should leave this option set to 'N'.
2383
2384config CMDLINE
2385 string "Built-in kernel command string"
2386 depends on CMDLINE_BOOL
2387 default ""
2388 help
2389 Enter arguments here that should be compiled into the kernel
2390 image and used at boot time. If the boot loader provides a
2391 command line at boot time, it is appended to this string to
2392 form the full kernel command line, when the system boots.
2393
2394 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2395 change this behavior.
2396
2397 In most cases, the command line (whether built-in or provided
2398 by the boot loader) should specify the device for the root
2399 file system.
2400
2401config CMDLINE_OVERRIDE
2402 bool "Built-in command line overrides boot loader arguments"
2403 depends on CMDLINE_BOOL && CMDLINE != ""
2404 help
2405 Set this option to 'Y' to have the kernel ignore the boot loader
2406 command line, and use ONLY the built-in command line.
2407
2408 This is used to work around broken boot loaders. This should
2409 be set to 'N' under normal conditions.
2410
2411config MODIFY_LDT_SYSCALL
2412 bool "Enable the LDT (local descriptor table)" if EXPERT
2413 default y
2414 help
2415 Linux can allow user programs to install a per-process x86
2416 Local Descriptor Table (LDT) using the modify_ldt(2) system
2417 call. This is required to run 16-bit or segmented code such as
2418 DOSEMU or some Wine programs. It is also used by some very old
2419 threading libraries.
2420
2421 Enabling this feature adds a small amount of overhead to
2422 context switches and increases the low-level kernel attack
2423 surface. Disabling it removes the modify_ldt(2) system call.
2424
2425 Saying 'N' here may make sense for embedded or server kernels.
2426
2427source "kernel/livepatch/Kconfig"
2428
2429endmenu
2430
2431config ARCH_HAS_ADD_PAGES
2432 def_bool y
2433 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2434
2435config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2436 def_bool y
2437
2438config USE_PERCPU_NUMA_NODE_ID
2439 def_bool y
2440 depends on NUMA
2441
2442menu "Power management and ACPI options"
2443
2444config ARCH_HIBERNATION_HEADER
2445 def_bool y
2446 depends on HIBERNATION
2447
2448source "kernel/power/Kconfig"
2449
2450source "drivers/acpi/Kconfig"
2451
2452config X86_APM_BOOT
2453 def_bool y
2454 depends on APM
2455
2456menuconfig APM
2457 tristate "APM (Advanced Power Management) BIOS support"
2458 depends on X86_32 && PM_SLEEP
2459 help
2460 APM is a BIOS specification for saving power using several different
2461 techniques. This is mostly useful for battery powered laptops with
2462 APM compliant BIOSes. If you say Y here, the system time will be
2463 reset after a RESUME operation, the /proc/apm device will provide
2464 battery status information, and user-space programs will receive
2465 notification of APM "events" (e.g. battery status change).
2466
2467 If you select "Y" here, you can disable actual use of the APM
2468 BIOS by passing the "apm=off" option to the kernel at boot time.
2469
2470 Note that the APM support is almost completely disabled for
2471 machines with more than one CPU.
2472
2473 In order to use APM, you will need supporting software. For location
2474 and more information, read <file:Documentation/power/apm-acpi.rst>
2475 and the Battery Powered Linux mini-HOWTO, available from
2476 <http://www.tldp.org/docs.html#howto>.
2477
2478 This driver does not spin down disk drives (see the hdparm(8)
2479 manpage ("man 8 hdparm") for that), and it doesn't turn off
2480 VESA-compliant "green" monitors.
2481
2482 This driver does not support the TI 4000M TravelMate and the ACER
2483 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2484 desktop machines also don't have compliant BIOSes, and this driver
2485 may cause those machines to panic during the boot phase.
2486
2487 Generally, if you don't have a battery in your machine, there isn't
2488 much point in using this driver and you should say N. If you get
2489 random kernel OOPSes or reboots that don't seem to be related to
2490 anything, try disabling/enabling this option (or disabling/enabling
2491 APM in your BIOS).
2492
2493 Some other things you should try when experiencing seemingly random,
2494 "weird" problems:
2495
2496 1) make sure that you have enough swap space and that it is
2497 enabled.
2498 2) pass the "no-hlt" option to the kernel
2499 3) switch on floating point emulation in the kernel and pass
2500 the "no387" option to the kernel
2501 4) pass the "floppy=nodma" option to the kernel
2502 5) pass the "mem=4M" option to the kernel (thereby disabling
2503 all but the first 4 MB of RAM)
2504 6) make sure that the CPU is not over clocked.
2505 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2506 8) disable the cache from your BIOS settings
2507 9) install a fan for the video card or exchange video RAM
2508 10) install a better fan for the CPU
2509 11) exchange RAM chips
2510 12) exchange the motherboard.
2511
2512 To compile this driver as a module, choose M here: the
2513 module will be called apm.
2514
2515if APM
2516
2517config APM_IGNORE_USER_SUSPEND
2518 bool "Ignore USER SUSPEND"
2519 help
2520 This option will ignore USER SUSPEND requests. On machines with a
2521 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2522 series notebooks, it is necessary to say Y because of a BIOS bug.
2523
2524config APM_DO_ENABLE
2525 bool "Enable PM at boot time"
2526 help
2527 Enable APM features at boot time. From page 36 of the APM BIOS
2528 specification: "When disabled, the APM BIOS does not automatically
2529 power manage devices, enter the Standby State, enter the Suspend
2530 State, or take power saving steps in response to CPU Idle calls."
2531 This driver will make CPU Idle calls when Linux is idle (unless this
2532 feature is turned off -- see "Do CPU IDLE calls", below). This
2533 should always save battery power, but more complicated APM features
2534 will be dependent on your BIOS implementation. You may need to turn
2535 this option off if your computer hangs at boot time when using APM
2536 support, or if it beeps continuously instead of suspending. Turn
2537 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2538 T400CDT. This is off by default since most machines do fine without
2539 this feature.
2540
2541config APM_CPU_IDLE
2542 depends on CPU_IDLE
2543 bool "Make CPU Idle calls when idle"
2544 help
2545 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2546 On some machines, this can activate improved power savings, such as
2547 a slowed CPU clock rate, when the machine is idle. These idle calls
2548 are made after the idle loop has run for some length of time (e.g.,
2549 333 mS). On some machines, this will cause a hang at boot time or
2550 whenever the CPU becomes idle. (On machines with more than one CPU,
2551 this option does nothing.)
2552
2553config APM_DISPLAY_BLANK
2554 bool "Enable console blanking using APM"
2555 help
2556 Enable console blanking using the APM. Some laptops can use this to
2557 turn off the LCD backlight when the screen blanker of the Linux
2558 virtual console blanks the screen. Note that this is only used by
2559 the virtual console screen blanker, and won't turn off the backlight
2560 when using the X Window system. This also doesn't have anything to
2561 do with your VESA-compliant power-saving monitor. Further, this
2562 option doesn't work for all laptops -- it might not turn off your
2563 backlight at all, or it might print a lot of errors to the console,
2564 especially if you are using gpm.
2565
2566config APM_ALLOW_INTS
2567 bool "Allow interrupts during APM BIOS calls"
2568 help
2569 Normally we disable external interrupts while we are making calls to
2570 the APM BIOS as a measure to lessen the effects of a badly behaving
2571 BIOS implementation. The BIOS should reenable interrupts if it
2572 needs to. Unfortunately, some BIOSes do not -- especially those in
2573 many of the newer IBM Thinkpads. If you experience hangs when you
2574 suspend, try setting this to Y. Otherwise, say N.
2575
2576endif # APM
2577
2578source "drivers/cpufreq/Kconfig"
2579
2580source "drivers/cpuidle/Kconfig"
2581
2582source "drivers/idle/Kconfig"
2583
2584endmenu
2585
2586
2587menu "Bus options (PCI etc.)"
2588
2589choice
2590 prompt "PCI access mode"
2591 depends on X86_32 && PCI
2592 default PCI_GOANY
2593 help
2594 On PCI systems, the BIOS can be used to detect the PCI devices and
2595 determine their configuration. However, some old PCI motherboards
2596 have BIOS bugs and may crash if this is done. Also, some embedded
2597 PCI-based systems don't have any BIOS at all. Linux can also try to
2598 detect the PCI hardware directly without using the BIOS.
2599
2600 With this option, you can specify how Linux should detect the
2601 PCI devices. If you choose "BIOS", the BIOS will be used,
2602 if you choose "Direct", the BIOS won't be used, and if you
2603 choose "MMConfig", then PCI Express MMCONFIG will be used.
2604 If you choose "Any", the kernel will try MMCONFIG, then the
2605 direct access method and falls back to the BIOS if that doesn't
2606 work. If unsure, go with the default, which is "Any".
2607
2608config PCI_GOBIOS
2609 bool "BIOS"
2610
2611config PCI_GOMMCONFIG
2612 bool "MMConfig"
2613
2614config PCI_GODIRECT
2615 bool "Direct"
2616
2617config PCI_GOOLPC
2618 bool "OLPC XO-1"
2619 depends on OLPC
2620
2621config PCI_GOANY
2622 bool "Any"
2623
2624endchoice
2625
2626config PCI_BIOS
2627 def_bool y
2628 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2629
2630# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2631config PCI_DIRECT
2632 def_bool y
2633 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2634
2635config PCI_MMCONFIG
2636 bool "Support mmconfig PCI config space access" if X86_64
2637 default y
2638 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2639 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2640
2641config PCI_OLPC
2642 def_bool y
2643 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2644
2645config PCI_XEN
2646 def_bool y
2647 depends on PCI && XEN
2648 select SWIOTLB_XEN
2649
2650config MMCONF_FAM10H
2651 def_bool y
2652 depends on X86_64 && PCI_MMCONFIG && ACPI
2653
2654config PCI_CNB20LE_QUIRK
2655 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2656 depends on PCI
2657 help
2658 Read the PCI windows out of the CNB20LE host bridge. This allows
2659 PCI hotplug to work on systems with the CNB20LE chipset which do
2660 not have ACPI.
2661
2662 There's no public spec for this chipset, and this functionality
2663 is known to be incomplete.
2664
2665 You should say N unless you know you need this.
2666
2667config ISA_BUS
2668 bool "ISA bus support on modern systems" if EXPERT
2669 help
2670 Expose ISA bus device drivers and options available for selection and
2671 configuration. Enable this option if your target machine has an ISA
2672 bus. ISA is an older system, displaced by PCI and newer bus
2673 architectures -- if your target machine is modern, it probably does
2674 not have an ISA bus.
2675
2676 If unsure, say N.
2677
2678# x86_64 have no ISA slots, but can have ISA-style DMA.
2679config ISA_DMA_API
2680 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2681 default y
2682 help
2683 Enables ISA-style DMA support for devices requiring such controllers.
2684 If unsure, say Y.
2685
2686if X86_32
2687
2688config ISA
2689 bool "ISA support"
2690 help
2691 Find out whether you have ISA slots on your motherboard. ISA is the
2692 name of a bus system, i.e. the way the CPU talks to the other stuff
2693 inside your box. Other bus systems are PCI, EISA, MicroChannel
2694 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2695 newer boards don't support it. If you have ISA, say Y, otherwise N.
2696
2697config SCx200
2698 tristate "NatSemi SCx200 support"
2699 help
2700 This provides basic support for National Semiconductor's
2701 (now AMD's) Geode processors. The driver probes for the
2702 PCI-IDs of several on-chip devices, so its a good dependency
2703 for other scx200_* drivers.
2704
2705 If compiled as a module, the driver is named scx200.
2706
2707config SCx200HR_TIMER
2708 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2709 depends on SCx200
2710 default y
2711 help
2712 This driver provides a clocksource built upon the on-chip
2713 27MHz high-resolution timer. Its also a workaround for
2714 NSC Geode SC-1100's buggy TSC, which loses time when the
2715 processor goes idle (as is done by the scheduler). The
2716 other workaround is idle=poll boot option.
2717
2718config OLPC
2719 bool "One Laptop Per Child support"
2720 depends on !X86_PAE
2721 select GPIOLIB
2722 select OF
2723 select OF_PROMTREE
2724 select IRQ_DOMAIN
2725 select OLPC_EC
2726 help
2727 Add support for detecting the unique features of the OLPC
2728 XO hardware.
2729
2730config OLPC_XO1_PM
2731 bool "OLPC XO-1 Power Management"
2732 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2733 help
2734 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2735
2736config OLPC_XO1_RTC
2737 bool "OLPC XO-1 Real Time Clock"
2738 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2739 help
2740 Add support for the XO-1 real time clock, which can be used as a
2741 programmable wakeup source.
2742
2743config OLPC_XO1_SCI
2744 bool "OLPC XO-1 SCI extras"
2745 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2746 depends on INPUT=y
2747 select POWER_SUPPLY
2748 help
2749 Add support for SCI-based features of the OLPC XO-1 laptop:
2750 - EC-driven system wakeups
2751 - Power button
2752 - Ebook switch
2753 - Lid switch
2754 - AC adapter status updates
2755 - Battery status updates
2756
2757config OLPC_XO15_SCI
2758 bool "OLPC XO-1.5 SCI extras"
2759 depends on OLPC && ACPI
2760 select POWER_SUPPLY
2761 help
2762 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2763 - EC-driven system wakeups
2764 - AC adapter status updates
2765 - Battery status updates
2766
2767config ALIX
2768 bool "PCEngines ALIX System Support (LED setup)"
2769 select GPIOLIB
2770 help
2771 This option enables system support for the PCEngines ALIX.
2772 At present this just sets up LEDs for GPIO control on
2773 ALIX2/3/6 boards. However, other system specific setup should
2774 get added here.
2775
2776 Note: You must still enable the drivers for GPIO and LED support
2777 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2778
2779 Note: You have to set alix.force=1 for boards with Award BIOS.
2780
2781config NET5501
2782 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2783 select GPIOLIB
2784 help
2785 This option enables system support for the Soekris Engineering net5501.
2786
2787config GEOS
2788 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2789 select GPIOLIB
2790 depends on DMI
2791 help
2792 This option enables system support for the Traverse Technologies GEOS.
2793
2794config TS5500
2795 bool "Technologic Systems TS-5500 platform support"
2796 depends on MELAN
2797 select CHECK_SIGNATURE
2798 select NEW_LEDS
2799 select LEDS_CLASS
2800 help
2801 This option enables system support for the Technologic Systems TS-5500.
2802
2803endif # X86_32
2804
2805config AMD_NB
2806 def_bool y
2807 depends on CPU_SUP_AMD && PCI
2808
2809config X86_SYSFB
2810 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2811 help
2812 Firmwares often provide initial graphics framebuffers so the BIOS,
2813 bootloader or kernel can show basic video-output during boot for
2814 user-guidance and debugging. Historically, x86 used the VESA BIOS
2815 Extensions and EFI-framebuffers for this, which are mostly limited
2816 to x86.
2817 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2818 framebuffers so the new generic system-framebuffer drivers can be
2819 used on x86. If the framebuffer is not compatible with the generic
2820 modes, it is advertised as fallback platform framebuffer so legacy
2821 drivers like efifb, vesafb and uvesafb can pick it up.
2822 If this option is not selected, all system framebuffers are always
2823 marked as fallback platform framebuffers as usual.
2824
2825 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2826 not be able to pick up generic system framebuffers if this option
2827 is selected. You are highly encouraged to enable simplefb as
2828 replacement if you select this option. simplefb can correctly deal
2829 with generic system framebuffers. But you should still keep vesafb
2830 and others enabled as fallback if a system framebuffer is
2831 incompatible with simplefb.
2832
2833 If unsure, say Y.
2834
2835endmenu
2836
2837
2838menu "Binary Emulations"
2839
2840config IA32_EMULATION
2841 bool "IA32 Emulation"
2842 depends on X86_64
2843 select ARCH_WANT_OLD_COMPAT_IPC
2844 select BINFMT_ELF
2845 select COMPAT_OLD_SIGACTION
2846 help
2847 Include code to run legacy 32-bit programs under a
2848 64-bit kernel. You should likely turn this on, unless you're
2849 100% sure that you don't have any 32-bit programs left.
2850
2851config IA32_AOUT
2852 tristate "IA32 a.out support"
2853 depends on IA32_EMULATION
2854 depends on BROKEN
2855 help
2856 Support old a.out binaries in the 32bit emulation.
2857
2858config X86_X32
2859 bool "x32 ABI for 64-bit mode"
2860 depends on X86_64
2861 help
2862 Include code to run binaries for the x32 native 32-bit ABI
2863 for 64-bit processors. An x32 process gets access to the
2864 full 64-bit register file and wide data path while leaving
2865 pointers at 32 bits for smaller memory footprint.
2866
2867 You will need a recent binutils (2.22 or later) with
2868 elf32_x86_64 support enabled to compile a kernel with this
2869 option set.
2870
2871config COMPAT_32
2872 def_bool y
2873 depends on IA32_EMULATION || X86_32
2874 select HAVE_UID16
2875 select OLD_SIGSUSPEND3
2876
2877config COMPAT
2878 def_bool y
2879 depends on IA32_EMULATION || X86_X32
2880
2881if COMPAT
2882config COMPAT_FOR_U64_ALIGNMENT
2883 def_bool y
2884
2885config SYSVIPC_COMPAT
2886 def_bool y
2887 depends on SYSVIPC
2888endif
2889
2890endmenu
2891
2892
2893config HAVE_ATOMIC_IOMAP
2894 def_bool y
2895 depends on X86_32
2896
2897source "drivers/firmware/Kconfig"
2898
2899source "arch/x86/kvm/Kconfig"
2900
2901source "arch/x86/Kconfig.assembler"