xref: /openbmc/linux/arch/x86/Kconfig (revision 13e7accb81d6c07993385af8342238ff22b41ac8)
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	select ZONE_DMA32
37
38config FORCE_DYNAMIC_FTRACE
39	def_bool y
40	depends on X86_32
41	depends on FUNCTION_TRACER
42	select DYNAMIC_FTRACE
43	help
44	  We keep the static function tracing (!DYNAMIC_FTRACE) around
45	  in order to test the non static function tracing in the
46	  generic code, as other architectures still use it. But we
47	  only need to keep it around for x86_64. No need to keep it
48	  for x86_32. For x86_32, force DYNAMIC_FTRACE.
49#
50# Arch settings
51#
52# ( Note that options that are marked 'if X86_64' could in principle be
53#   ported to 32-bit as well. )
54#
55config X86
56	def_bool y
57	#
58	# Note: keep this list sorted alphabetically
59	#
60	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
61	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
62	select ARCH_32BIT_OFF_T			if X86_32
63	select ARCH_CLOCKSOURCE_INIT
64	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
71	select ARCH_HAS_CACHE_LINE_SIZE
72	select ARCH_HAS_CURRENT_STACK_POINTER
73	select ARCH_HAS_DEBUG_VIRTUAL
74	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
75	select ARCH_HAS_DEVMEM_IS_ALLOWED
76	select ARCH_HAS_EARLY_DEBUG		if KGDB
77	select ARCH_HAS_ELF_RANDOMIZE
78	select ARCH_HAS_FAST_MULTIPLIER
79	select ARCH_HAS_FORTIFY_SOURCE
80	select ARCH_HAS_GCOV_PROFILE_ALL
81	select ARCH_HAS_KCOV			if X86_64
82	select ARCH_HAS_MEM_ENCRYPT
83	select ARCH_HAS_MEMBARRIER_SYNC_CORE
84	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85	select ARCH_HAS_PMEM_API		if X86_64
86	select ARCH_HAS_PTE_DEVMAP		if X86_64
87	select ARCH_HAS_PTE_SPECIAL
88	select ARCH_HAS_NONLEAF_PMD_YOUNG	if PGTABLE_LEVELS > 2
89	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
90	select ARCH_HAS_COPY_MC			if X86_64
91	select ARCH_HAS_SET_MEMORY
92	select ARCH_HAS_SET_DIRECT_MAP
93	select ARCH_HAS_STRICT_KERNEL_RWX
94	select ARCH_HAS_STRICT_MODULE_RWX
95	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
96	select ARCH_HAS_SYSCALL_WRAPPER
97	select ARCH_HAS_UBSAN_SANITIZE_ALL
98	select ARCH_HAS_DEBUG_WX
99	select ARCH_HAS_ZONE_DMA_SET if EXPERT
100	select ARCH_HAVE_NMI_SAFE_CMPXCHG
101	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
102	select ARCH_MIGHT_HAVE_PC_PARPORT
103	select ARCH_MIGHT_HAVE_PC_SERIO
104	select ARCH_STACKWALK
105	select ARCH_SUPPORTS_ACPI
106	select ARCH_SUPPORTS_ATOMIC_RMW
107	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
108	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
109	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
110	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
111	select ARCH_SUPPORTS_CFI_CLANG		if X86_64
112	select ARCH_USES_CFI_TRAPS		if X86_64 && CFI_CLANG
113	select ARCH_SUPPORTS_LTO_CLANG
114	select ARCH_SUPPORTS_LTO_CLANG_THIN
115	select ARCH_USE_BUILTIN_BSWAP
116	select ARCH_USE_MEMTEST
117	select ARCH_USE_QUEUED_RWLOCKS
118	select ARCH_USE_QUEUED_SPINLOCKS
119	select ARCH_USE_SYM_ANNOTATIONS
120	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
121	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
122	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
123	select ARCH_WANTS_NO_INSTR
124	select ARCH_WANT_GENERAL_HUGETLB
125	select ARCH_WANT_HUGE_PMD_SHARE
126	select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP	if X86_64
127	select ARCH_WANT_LD_ORPHAN_WARN
128	select ARCH_WANTS_THP_SWAP		if X86_64
129	select ARCH_HAS_PARANOID_L1D_FLUSH
130	select BUILDTIME_TABLE_SORT
131	select CLKEVT_I8253
132	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
133	select CLOCKSOURCE_WATCHDOG
134	# Word-size accesses may read uninitialized data past the trailing \0
135	# in strings and cause false KMSAN reports.
136	select DCACHE_WORD_ACCESS		if !KMSAN
137	select DYNAMIC_SIGFRAME
138	select EDAC_ATOMIC_SCRUB
139	select EDAC_SUPPORT
140	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
141	select GENERIC_CLOCKEVENTS_MIN_ADJUST
142	select GENERIC_CMOS_UPDATE
143	select GENERIC_CPU_AUTOPROBE
144	select GENERIC_CPU_VULNERABILITIES
145	select GENERIC_EARLY_IOREMAP
146	select GENERIC_ENTRY
147	select GENERIC_IOMAP
148	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
149	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
150	select GENERIC_IRQ_MIGRATION		if SMP
151	select GENERIC_IRQ_PROBE
152	select GENERIC_IRQ_RESERVATION_MODE
153	select GENERIC_IRQ_SHOW
154	select GENERIC_PENDING_IRQ		if SMP
155	select GENERIC_PTDUMP
156	select GENERIC_SMP_IDLE_THREAD
157	select GENERIC_TIME_VSYSCALL
158	select GENERIC_GETTIMEOFDAY
159	select GENERIC_VDSO_TIME_NS
160	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
161	select HARDIRQS_SW_RESEND
162	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
163	select HAVE_ACPI_APEI			if ACPI
164	select HAVE_ACPI_APEI_NMI		if ACPI
165	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
166	select HAVE_ARCH_AUDITSYSCALL
167	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
168	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
169	select HAVE_ARCH_JUMP_LABEL
170	select HAVE_ARCH_JUMP_LABEL_RELATIVE
171	select HAVE_ARCH_KASAN			if X86_64
172	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
173	select HAVE_ARCH_KFENCE
174	select HAVE_ARCH_KMSAN			if X86_64
175	select HAVE_ARCH_KGDB
176	select HAVE_ARCH_MMAP_RND_BITS		if MMU
177	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
178	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
179	select HAVE_ARCH_PREL32_RELOCATIONS
180	select HAVE_ARCH_SECCOMP_FILTER
181	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
182	select HAVE_ARCH_STACKLEAK
183	select HAVE_ARCH_TRACEHOOK
184	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
185	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
186	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
187	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
188	select HAVE_ARCH_VMAP_STACK		if X86_64
189	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
190	select HAVE_ARCH_WITHIN_STACK_FRAMES
191	select HAVE_ASM_MODVERSIONS
192	select HAVE_CMPXCHG_DOUBLE
193	select HAVE_CMPXCHG_LOCAL
194	select HAVE_CONTEXT_TRACKING_USER		if X86_64
195	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
196	select HAVE_C_RECORDMCOUNT
197	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
198	select HAVE_BUILDTIME_MCOUNT_SORT
199	select HAVE_DEBUG_KMEMLEAK
200	select HAVE_DMA_CONTIGUOUS
201	select HAVE_DYNAMIC_FTRACE
202	select HAVE_DYNAMIC_FTRACE_WITH_REGS
203	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
204	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
205	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
206	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
207	select HAVE_EBPF_JIT
208	select HAVE_EFFICIENT_UNALIGNED_ACCESS
209	select HAVE_EISA
210	select HAVE_EXIT_THREAD
211	select HAVE_FAST_GUP
212	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
213	select HAVE_FTRACE_MCOUNT_RECORD
214	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
215	select HAVE_FUNCTION_TRACER
216	select HAVE_GCC_PLUGINS
217	select HAVE_HW_BREAKPOINT
218	select HAVE_IOREMAP_PROT
219	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
220	select HAVE_IRQ_TIME_ACCOUNTING
221	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
222	select HAVE_KERNEL_BZIP2
223	select HAVE_KERNEL_GZIP
224	select HAVE_KERNEL_LZ4
225	select HAVE_KERNEL_LZMA
226	select HAVE_KERNEL_LZO
227	select HAVE_KERNEL_XZ
228	select HAVE_KERNEL_ZSTD
229	select HAVE_KPROBES
230	select HAVE_KPROBES_ON_FTRACE
231	select HAVE_FUNCTION_ERROR_INJECTION
232	select HAVE_KRETPROBES
233	select HAVE_RETHOOK
234	select HAVE_KVM
235	select HAVE_LIVEPATCH			if X86_64
236	select HAVE_MIXED_BREAKPOINTS_REGS
237	select HAVE_MOD_ARCH_SPECIFIC
238	select HAVE_MOVE_PMD
239	select HAVE_MOVE_PUD
240	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
241	select HAVE_NMI
242	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
243	select HAVE_OBJTOOL			if X86_64
244	select HAVE_OPTPROBES
245	select HAVE_PCSPKR_PLATFORM
246	select HAVE_PERF_EVENTS
247	select HAVE_PERF_EVENTS_NMI
248	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
249	select HAVE_PCI
250	select HAVE_PERF_REGS
251	select HAVE_PERF_USER_STACK_DUMP
252	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
253	select MMU_GATHER_MERGE_VMAS
254	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
255	select HAVE_REGS_AND_STACK_ACCESS_API
256	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
257	select HAVE_FUNCTION_ARG_ACCESS_API
258	select HAVE_SETUP_PER_CPU_AREA
259	select HAVE_SOFTIRQ_ON_OWN_STACK
260	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
261	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
262	select HAVE_STATIC_CALL
263	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
264	select HAVE_PREEMPT_DYNAMIC_CALL
265	select HAVE_RSEQ
266	select HAVE_RUST			if X86_64
267	select HAVE_SYSCALL_TRACEPOINTS
268	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
269	select HAVE_UNSTABLE_SCHED_CLOCK
270	select HAVE_USER_RETURN_NOTIFIER
271	select HAVE_GENERIC_VDSO
272	select HOTPLUG_SMT			if SMP
273	select IRQ_FORCED_THREADING
274	select NEED_PER_CPU_EMBED_FIRST_CHUNK
275	select NEED_PER_CPU_PAGE_FIRST_CHUNK
276	select NEED_SG_DMA_LENGTH
277	select PCI_DOMAINS			if PCI
278	select PCI_LOCKLESS_CONFIG		if PCI
279	select PERF_EVENTS
280	select RTC_LIB
281	select RTC_MC146818_LIB
282	select SPARSE_IRQ
283	select SRCU
284	select SYSCTL_EXCEPTION_TRACE
285	select THREAD_INFO_IN_TASK
286	select TRACE_IRQFLAGS_SUPPORT
287	select TRACE_IRQFLAGS_NMI_SUPPORT
288	select USER_STACKTRACE_SUPPORT
289	select HAVE_ARCH_KCSAN			if X86_64
290	select X86_FEATURE_NAMES		if PROC_FS
291	select PROC_PID_ARCH_STATUS		if PROC_FS
292	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
293	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
294	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
295
296config INSTRUCTION_DECODER
297	def_bool y
298	depends on KPROBES || PERF_EVENTS || UPROBES
299
300config OUTPUT_FORMAT
301	string
302	default "elf32-i386" if X86_32
303	default "elf64-x86-64" if X86_64
304
305config LOCKDEP_SUPPORT
306	def_bool y
307
308config STACKTRACE_SUPPORT
309	def_bool y
310
311config MMU
312	def_bool y
313
314config ARCH_MMAP_RND_BITS_MIN
315	default 28 if 64BIT
316	default 8
317
318config ARCH_MMAP_RND_BITS_MAX
319	default 32 if 64BIT
320	default 16
321
322config ARCH_MMAP_RND_COMPAT_BITS_MIN
323	default 8
324
325config ARCH_MMAP_RND_COMPAT_BITS_MAX
326	default 16
327
328config SBUS
329	bool
330
331config GENERIC_ISA_DMA
332	def_bool y
333	depends on ISA_DMA_API
334
335config GENERIC_CSUM
336	bool
337	default y if KMSAN || KASAN
338
339config GENERIC_BUG
340	def_bool y
341	depends on BUG
342	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
343
344config GENERIC_BUG_RELATIVE_POINTERS
345	bool
346
347config ARCH_MAY_HAVE_PC_FDC
348	def_bool y
349	depends on ISA_DMA_API
350
351config GENERIC_CALIBRATE_DELAY
352	def_bool y
353
354config ARCH_HAS_CPU_RELAX
355	def_bool y
356
357config ARCH_HIBERNATION_POSSIBLE
358	def_bool y
359
360config ARCH_NR_GPIO
361	int
362	default 1024 if X86_64
363	default 512
364
365config ARCH_SUSPEND_POSSIBLE
366	def_bool y
367
368config AUDIT_ARCH
369	def_bool y if X86_64
370
371config KASAN_SHADOW_OFFSET
372	hex
373	depends on KASAN
374	default 0xdffffc0000000000
375
376config HAVE_INTEL_TXT
377	def_bool y
378	depends on INTEL_IOMMU && ACPI
379
380config X86_32_SMP
381	def_bool y
382	depends on X86_32 && SMP
383
384config X86_64_SMP
385	def_bool y
386	depends on X86_64 && SMP
387
388config ARCH_SUPPORTS_UPROBES
389	def_bool y
390
391config FIX_EARLYCON_MEM
392	def_bool y
393
394config DYNAMIC_PHYSICAL_MASK
395	bool
396
397config PGTABLE_LEVELS
398	int
399	default 5 if X86_5LEVEL
400	default 4 if X86_64
401	default 3 if X86_PAE
402	default 2
403
404config CC_HAS_SANE_STACKPROTECTOR
405	bool
406	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
407	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
408	help
409	  We have to make sure stack protector is unconditionally disabled if
410	  the compiler produces broken code or if it does not let us control
411	  the segment on 32-bit kernels.
412
413menu "Processor type and features"
414
415config SMP
416	bool "Symmetric multi-processing support"
417	help
418	  This enables support for systems with more than one CPU. If you have
419	  a system with only one CPU, say N. If you have a system with more
420	  than one CPU, say Y.
421
422	  If you say N here, the kernel will run on uni- and multiprocessor
423	  machines, but will use only one CPU of a multiprocessor machine. If
424	  you say Y here, the kernel will run on many, but not all,
425	  uniprocessor machines. On a uniprocessor machine, the kernel
426	  will run faster if you say N here.
427
428	  Note that if you say Y here and choose architecture "586" or
429	  "Pentium" under "Processor family", the kernel will not work on 486
430	  architectures. Similarly, multiprocessor kernels for the "PPro"
431	  architecture may not work on all Pentium based boards.
432
433	  People using multiprocessor machines who say Y here should also say
434	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
435	  Management" code will be disabled if you say Y here.
436
437	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
438	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
439	  <http://www.tldp.org/docs.html#howto>.
440
441	  If you don't know what to do here, say N.
442
443config X86_FEATURE_NAMES
444	bool "Processor feature human-readable names" if EMBEDDED
445	default y
446	help
447	  This option compiles in a table of x86 feature bits and corresponding
448	  names.  This is required to support /proc/cpuinfo and a few kernel
449	  messages.  You can disable this to save space, at the expense of
450	  making those few kernel messages show numeric feature bits instead.
451
452	  If in doubt, say Y.
453
454config X86_X2APIC
455	bool "Support x2apic"
456	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
457	help
458	  This enables x2apic support on CPUs that have this feature.
459
460	  This allows 32-bit apic IDs (so it can support very large systems),
461	  and accesses the local apic via MSRs not via mmio.
462
463	  Some Intel systems circa 2022 and later are locked into x2APIC mode
464	  and can not fall back to the legacy APIC modes if SGX or TDX are
465	  enabled in the BIOS.  They will be unable to boot without enabling
466	  this option.
467
468	  If you don't know what to do here, say N.
469
470config X86_MPPARSE
471	bool "Enable MPS table" if ACPI
472	default y
473	depends on X86_LOCAL_APIC
474	help
475	  For old smp systems that do not have proper acpi support. Newer systems
476	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
477
478config GOLDFISH
479	def_bool y
480	depends on X86_GOLDFISH
481
482config X86_CPU_RESCTRL
483	bool "x86 CPU resource control support"
484	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
485	select KERNFS
486	select PROC_CPU_RESCTRL		if PROC_FS
487	help
488	  Enable x86 CPU resource control support.
489
490	  Provide support for the allocation and monitoring of system resources
491	  usage by the CPU.
492
493	  Intel calls this Intel Resource Director Technology
494	  (Intel(R) RDT). More information about RDT can be found in the
495	  Intel x86 Architecture Software Developer Manual.
496
497	  AMD calls this AMD Platform Quality of Service (AMD QoS).
498	  More information about AMD QoS can be found in the AMD64 Technology
499	  Platform Quality of Service Extensions manual.
500
501	  Say N if unsure.
502
503if X86_32
504config X86_BIGSMP
505	bool "Support for big SMP systems with more than 8 CPUs"
506	depends on SMP
507	help
508	  This option is needed for the systems that have more than 8 CPUs.
509
510config X86_EXTENDED_PLATFORM
511	bool "Support for extended (non-PC) x86 platforms"
512	default y
513	help
514	  If you disable this option then the kernel will only support
515	  standard PC platforms. (which covers the vast majority of
516	  systems out there.)
517
518	  If you enable this option then you'll be able to select support
519	  for the following (non-PC) 32 bit x86 platforms:
520		Goldfish (Android emulator)
521		AMD Elan
522		RDC R-321x SoC
523		SGI 320/540 (Visual Workstation)
524		STA2X11-based (e.g. Northville)
525		Moorestown MID devices
526
527	  If you have one of these systems, or if you want to build a
528	  generic distribution kernel, say Y here - otherwise say N.
529endif # X86_32
530
531if X86_64
532config X86_EXTENDED_PLATFORM
533	bool "Support for extended (non-PC) x86 platforms"
534	default y
535	help
536	  If you disable this option then the kernel will only support
537	  standard PC platforms. (which covers the vast majority of
538	  systems out there.)
539
540	  If you enable this option then you'll be able to select support
541	  for the following (non-PC) 64 bit x86 platforms:
542		Numascale NumaChip
543		ScaleMP vSMP
544		SGI Ultraviolet
545
546	  If you have one of these systems, or if you want to build a
547	  generic distribution kernel, say Y here - otherwise say N.
548endif # X86_64
549# This is an alphabetically sorted list of 64 bit extended platforms
550# Please maintain the alphabetic order if and when there are additions
551config X86_NUMACHIP
552	bool "Numascale NumaChip"
553	depends on X86_64
554	depends on X86_EXTENDED_PLATFORM
555	depends on NUMA
556	depends on SMP
557	depends on X86_X2APIC
558	depends on PCI_MMCONFIG
559	help
560	  Adds support for Numascale NumaChip large-SMP systems. Needed to
561	  enable more than ~168 cores.
562	  If you don't have one of these, you should say N here.
563
564config X86_VSMP
565	bool "ScaleMP vSMP"
566	select HYPERVISOR_GUEST
567	select PARAVIRT
568	depends on X86_64 && PCI
569	depends on X86_EXTENDED_PLATFORM
570	depends on SMP
571	help
572	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
573	  supposed to run on these EM64T-based machines.  Only choose this option
574	  if you have one of these machines.
575
576config X86_UV
577	bool "SGI Ultraviolet"
578	depends on X86_64
579	depends on X86_EXTENDED_PLATFORM
580	depends on NUMA
581	depends on EFI
582	depends on KEXEC_CORE
583	depends on X86_X2APIC
584	depends on PCI
585	help
586	  This option is needed in order to support SGI Ultraviolet systems.
587	  If you don't have one of these, you should say N here.
588
589# Following is an alphabetically sorted list of 32 bit extended platforms
590# Please maintain the alphabetic order if and when there are additions
591
592config X86_GOLDFISH
593	bool "Goldfish (Virtual Platform)"
594	depends on X86_EXTENDED_PLATFORM
595	help
596	  Enable support for the Goldfish virtual platform used primarily
597	  for Android development. Unless you are building for the Android
598	  Goldfish emulator say N here.
599
600config X86_INTEL_CE
601	bool "CE4100 TV platform"
602	depends on PCI
603	depends on PCI_GODIRECT
604	depends on X86_IO_APIC
605	depends on X86_32
606	depends on X86_EXTENDED_PLATFORM
607	select X86_REBOOTFIXUPS
608	select OF
609	select OF_EARLY_FLATTREE
610	help
611	  Select for the Intel CE media processor (CE4100) SOC.
612	  This option compiles in support for the CE4100 SOC for settop
613	  boxes and media devices.
614
615config X86_INTEL_MID
616	bool "Intel MID platform support"
617	depends on X86_EXTENDED_PLATFORM
618	depends on X86_PLATFORM_DEVICES
619	depends on PCI
620	depends on X86_64 || (PCI_GOANY && X86_32)
621	depends on X86_IO_APIC
622	select I2C
623	select DW_APB_TIMER
624	select INTEL_SCU_PCI
625	help
626	  Select to build a kernel capable of supporting Intel MID (Mobile
627	  Internet Device) platform systems which do not have the PCI legacy
628	  interfaces. If you are building for a PC class system say N here.
629
630	  Intel MID platforms are based on an Intel processor and chipset which
631	  consume less power than most of the x86 derivatives.
632
633config X86_INTEL_QUARK
634	bool "Intel Quark platform support"
635	depends on X86_32
636	depends on X86_EXTENDED_PLATFORM
637	depends on X86_PLATFORM_DEVICES
638	depends on X86_TSC
639	depends on PCI
640	depends on PCI_GOANY
641	depends on X86_IO_APIC
642	select IOSF_MBI
643	select INTEL_IMR
644	select COMMON_CLK
645	help
646	  Select to include support for Quark X1000 SoC.
647	  Say Y here if you have a Quark based system such as the Arduino
648	  compatible Intel Galileo.
649
650config X86_INTEL_LPSS
651	bool "Intel Low Power Subsystem Support"
652	depends on X86 && ACPI && PCI
653	select COMMON_CLK
654	select PINCTRL
655	select IOSF_MBI
656	help
657	  Select to build support for Intel Low Power Subsystem such as
658	  found on Intel Lynxpoint PCH. Selecting this option enables
659	  things like clock tree (common clock framework) and pincontrol
660	  which are needed by the LPSS peripheral drivers.
661
662config X86_AMD_PLATFORM_DEVICE
663	bool "AMD ACPI2Platform devices support"
664	depends on ACPI
665	select COMMON_CLK
666	select PINCTRL
667	help
668	  Select to interpret AMD specific ACPI device to platform device
669	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
670	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
671	  implemented under PINCTRL subsystem.
672
673config IOSF_MBI
674	tristate "Intel SoC IOSF Sideband support for SoC platforms"
675	depends on PCI
676	help
677	  This option enables sideband register access support for Intel SoC
678	  platforms. On these platforms the IOSF sideband is used in lieu of
679	  MSR's for some register accesses, mostly but not limited to thermal
680	  and power. Drivers may query the availability of this device to
681	  determine if they need the sideband in order to work on these
682	  platforms. The sideband is available on the following SoC products.
683	  This list is not meant to be exclusive.
684	   - BayTrail
685	   - Braswell
686	   - Quark
687
688	  You should say Y if you are running a kernel on one of these SoC's.
689
690config IOSF_MBI_DEBUG
691	bool "Enable IOSF sideband access through debugfs"
692	depends on IOSF_MBI && DEBUG_FS
693	help
694	  Select this option to expose the IOSF sideband access registers (MCR,
695	  MDR, MCRX) through debugfs to write and read register information from
696	  different units on the SoC. This is most useful for obtaining device
697	  state information for debug and analysis. As this is a general access
698	  mechanism, users of this option would have specific knowledge of the
699	  device they want to access.
700
701	  If you don't require the option or are in doubt, say N.
702
703config X86_RDC321X
704	bool "RDC R-321x SoC"
705	depends on X86_32
706	depends on X86_EXTENDED_PLATFORM
707	select M486
708	select X86_REBOOTFIXUPS
709	help
710	  This option is needed for RDC R-321x system-on-chip, also known
711	  as R-8610-(G).
712	  If you don't have one of these chips, you should say N here.
713
714config X86_32_NON_STANDARD
715	bool "Support non-standard 32-bit SMP architectures"
716	depends on X86_32 && SMP
717	depends on X86_EXTENDED_PLATFORM
718	help
719	  This option compiles in the bigsmp and STA2X11 default
720	  subarchitectures.  It is intended for a generic binary
721	  kernel. If you select them all, kernel will probe it one by
722	  one and will fallback to default.
723
724# Alphabetically sorted list of Non standard 32 bit platforms
725
726config X86_SUPPORTS_MEMORY_FAILURE
727	def_bool y
728	# MCE code calls memory_failure():
729	depends on X86_MCE
730	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
731	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
732	depends on X86_64 || !SPARSEMEM
733	select ARCH_SUPPORTS_MEMORY_FAILURE
734
735config STA2X11
736	bool "STA2X11 Companion Chip Support"
737	depends on X86_32_NON_STANDARD && PCI
738	select SWIOTLB
739	select MFD_STA2X11
740	select GPIOLIB
741	help
742	  This adds support for boards based on the STA2X11 IO-Hub,
743	  a.k.a. "ConneXt". The chip is used in place of the standard
744	  PC chipset, so all "standard" peripherals are missing. If this
745	  option is selected the kernel will still be able to boot on
746	  standard PC machines.
747
748config X86_32_IRIS
749	tristate "Eurobraille/Iris poweroff module"
750	depends on X86_32
751	help
752	  The Iris machines from EuroBraille do not have APM or ACPI support
753	  to shut themselves down properly.  A special I/O sequence is
754	  needed to do so, which is what this module does at
755	  kernel shutdown.
756
757	  This is only for Iris machines from EuroBraille.
758
759	  If unused, say N.
760
761config SCHED_OMIT_FRAME_POINTER
762	def_bool y
763	prompt "Single-depth WCHAN output"
764	depends on X86
765	help
766	  Calculate simpler /proc/<PID>/wchan values. If this option
767	  is disabled then wchan values will recurse back to the
768	  caller function. This provides more accurate wchan values,
769	  at the expense of slightly more scheduling overhead.
770
771	  If in doubt, say "Y".
772
773menuconfig HYPERVISOR_GUEST
774	bool "Linux guest support"
775	help
776	  Say Y here to enable options for running Linux under various hyper-
777	  visors. This option enables basic hypervisor detection and platform
778	  setup.
779
780	  If you say N, all options in this submenu will be skipped and
781	  disabled, and Linux guest support won't be built in.
782
783if HYPERVISOR_GUEST
784
785config PARAVIRT
786	bool "Enable paravirtualization code"
787	depends on HAVE_STATIC_CALL
788	help
789	  This changes the kernel so it can modify itself when it is run
790	  under a hypervisor, potentially improving performance significantly
791	  over full virtualization.  However, when run without a hypervisor
792	  the kernel is theoretically slower and slightly larger.
793
794config PARAVIRT_XXL
795	bool
796
797config PARAVIRT_DEBUG
798	bool "paravirt-ops debugging"
799	depends on PARAVIRT && DEBUG_KERNEL
800	help
801	  Enable to debug paravirt_ops internals.  Specifically, BUG if
802	  a paravirt_op is missing when it is called.
803
804config PARAVIRT_SPINLOCKS
805	bool "Paravirtualization layer for spinlocks"
806	depends on PARAVIRT && SMP
807	help
808	  Paravirtualized spinlocks allow a pvops backend to replace the
809	  spinlock implementation with something virtualization-friendly
810	  (for example, block the virtual CPU rather than spinning).
811
812	  It has a minimal impact on native kernels and gives a nice performance
813	  benefit on paravirtualized KVM / Xen kernels.
814
815	  If you are unsure how to answer this question, answer Y.
816
817config X86_HV_CALLBACK_VECTOR
818	def_bool n
819
820source "arch/x86/xen/Kconfig"
821
822config KVM_GUEST
823	bool "KVM Guest support (including kvmclock)"
824	depends on PARAVIRT
825	select PARAVIRT_CLOCK
826	select ARCH_CPUIDLE_HALTPOLL
827	select X86_HV_CALLBACK_VECTOR
828	default y
829	help
830	  This option enables various optimizations for running under the KVM
831	  hypervisor. It includes a paravirtualized clock, so that instead
832	  of relying on a PIT (or probably other) emulation by the
833	  underlying device model, the host provides the guest with
834	  timing infrastructure such as time of day, and system time
835
836config ARCH_CPUIDLE_HALTPOLL
837	def_bool n
838	prompt "Disable host haltpoll when loading haltpoll driver"
839	help
840	  If virtualized under KVM, disable host haltpoll.
841
842config PVH
843	bool "Support for running PVH guests"
844	help
845	  This option enables the PVH entry point for guest virtual machines
846	  as specified in the x86/HVM direct boot ABI.
847
848config PARAVIRT_TIME_ACCOUNTING
849	bool "Paravirtual steal time accounting"
850	depends on PARAVIRT
851	help
852	  Select this option to enable fine granularity task steal time
853	  accounting. Time spent executing other tasks in parallel with
854	  the current vCPU is discounted from the vCPU power. To account for
855	  that, there can be a small performance impact.
856
857	  If in doubt, say N here.
858
859config PARAVIRT_CLOCK
860	bool
861
862config JAILHOUSE_GUEST
863	bool "Jailhouse non-root cell support"
864	depends on X86_64 && PCI
865	select X86_PM_TIMER
866	help
867	  This option allows to run Linux as guest in a Jailhouse non-root
868	  cell. You can leave this option disabled if you only want to start
869	  Jailhouse and run Linux afterwards in the root cell.
870
871config ACRN_GUEST
872	bool "ACRN Guest support"
873	depends on X86_64
874	select X86_HV_CALLBACK_VECTOR
875	help
876	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
877	  a flexible, lightweight reference open-source hypervisor, built with
878	  real-time and safety-criticality in mind. It is built for embedded
879	  IOT with small footprint and real-time features. More details can be
880	  found in https://projectacrn.org/.
881
882config INTEL_TDX_GUEST
883	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
884	depends on X86_64 && CPU_SUP_INTEL
885	depends on X86_X2APIC
886	select ARCH_HAS_CC_PLATFORM
887	select X86_MEM_ENCRYPT
888	select X86_MCE
889	help
890	  Support running as a guest under Intel TDX.  Without this support,
891	  the guest kernel can not boot or run under TDX.
892	  TDX includes memory encryption and integrity capabilities
893	  which protect the confidentiality and integrity of guest
894	  memory contents and CPU state. TDX guests are protected from
895	  some attacks from the VMM.
896
897endif # HYPERVISOR_GUEST
898
899source "arch/x86/Kconfig.cpu"
900
901config HPET_TIMER
902	def_bool X86_64
903	prompt "HPET Timer Support" if X86_32
904	help
905	  Use the IA-PC HPET (High Precision Event Timer) to manage
906	  time in preference to the PIT and RTC, if a HPET is
907	  present.
908	  HPET is the next generation timer replacing legacy 8254s.
909	  The HPET provides a stable time base on SMP
910	  systems, unlike the TSC, but it is more expensive to access,
911	  as it is off-chip.  The interface used is documented
912	  in the HPET spec, revision 1.
913
914	  You can safely choose Y here.  However, HPET will only be
915	  activated if the platform and the BIOS support this feature.
916	  Otherwise the 8254 will be used for timing services.
917
918	  Choose N to continue using the legacy 8254 timer.
919
920config HPET_EMULATE_RTC
921	def_bool y
922	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
923
924# Mark as expert because too many people got it wrong.
925# The code disables itself when not needed.
926config DMI
927	default y
928	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
929	bool "Enable DMI scanning" if EXPERT
930	help
931	  Enabled scanning of DMI to identify machine quirks. Say Y
932	  here unless you have verified that your setup is not
933	  affected by entries in the DMI blacklist. Required by PNP
934	  BIOS code.
935
936config GART_IOMMU
937	bool "Old AMD GART IOMMU support"
938	select DMA_OPS
939	select IOMMU_HELPER
940	select SWIOTLB
941	depends on X86_64 && PCI && AMD_NB
942	help
943	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
944	  GART based hardware IOMMUs.
945
946	  The GART supports full DMA access for devices with 32-bit access
947	  limitations, on systems with more than 3 GB. This is usually needed
948	  for USB, sound, many IDE/SATA chipsets and some other devices.
949
950	  Newer systems typically have a modern AMD IOMMU, supported via
951	  the CONFIG_AMD_IOMMU=y config option.
952
953	  In normal configurations this driver is only active when needed:
954	  there's more than 3 GB of memory and the system contains a
955	  32-bit limited device.
956
957	  If unsure, say Y.
958
959config BOOT_VESA_SUPPORT
960	bool
961	help
962	  If true, at least one selected framebuffer driver can take advantage
963	  of VESA video modes set at an early boot stage via the vga= parameter.
964
965config MAXSMP
966	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
967	depends on X86_64 && SMP && DEBUG_KERNEL
968	select CPUMASK_OFFSTACK
969	help
970	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
971	  If unsure, say N.
972
973#
974# The maximum number of CPUs supported:
975#
976# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
977# and which can be configured interactively in the
978# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
979#
980# The ranges are different on 32-bit and 64-bit kernels, depending on
981# hardware capabilities and scalability features of the kernel.
982#
983# ( If MAXSMP is enabled we just use the highest possible value and disable
984#   interactive configuration. )
985#
986
987config NR_CPUS_RANGE_BEGIN
988	int
989	default NR_CPUS_RANGE_END if MAXSMP
990	default    1 if !SMP
991	default    2
992
993config NR_CPUS_RANGE_END
994	int
995	depends on X86_32
996	default   64 if  SMP &&  X86_BIGSMP
997	default    8 if  SMP && !X86_BIGSMP
998	default    1 if !SMP
999
1000config NR_CPUS_RANGE_END
1001	int
1002	depends on X86_64
1003	default 8192 if  SMP && CPUMASK_OFFSTACK
1004	default  512 if  SMP && !CPUMASK_OFFSTACK
1005	default    1 if !SMP
1006
1007config NR_CPUS_DEFAULT
1008	int
1009	depends on X86_32
1010	default   32 if  X86_BIGSMP
1011	default    8 if  SMP
1012	default    1 if !SMP
1013
1014config NR_CPUS_DEFAULT
1015	int
1016	depends on X86_64
1017	default 8192 if  MAXSMP
1018	default   64 if  SMP
1019	default    1 if !SMP
1020
1021config NR_CPUS
1022	int "Maximum number of CPUs" if SMP && !MAXSMP
1023	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1024	default NR_CPUS_DEFAULT
1025	help
1026	  This allows you to specify the maximum number of CPUs which this
1027	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1028	  supported value is 8192, otherwise the maximum value is 512.  The
1029	  minimum value which makes sense is 2.
1030
1031	  This is purely to save memory: each supported CPU adds about 8KB
1032	  to the kernel image.
1033
1034config SCHED_CLUSTER
1035	bool "Cluster scheduler support"
1036	depends on SMP
1037	default y
1038	help
1039	  Cluster scheduler support improves the CPU scheduler's decision
1040	  making when dealing with machines that have clusters of CPUs.
1041	  Cluster usually means a couple of CPUs which are placed closely
1042	  by sharing mid-level caches, last-level cache tags or internal
1043	  busses.
1044
1045config SCHED_SMT
1046	def_bool y if SMP
1047
1048config SCHED_MC
1049	def_bool y
1050	prompt "Multi-core scheduler support"
1051	depends on SMP
1052	help
1053	  Multi-core scheduler support improves the CPU scheduler's decision
1054	  making when dealing with multi-core CPU chips at a cost of slightly
1055	  increased overhead in some places. If unsure say N here.
1056
1057config SCHED_MC_PRIO
1058	bool "CPU core priorities scheduler support"
1059	depends on SCHED_MC && CPU_SUP_INTEL
1060	select X86_INTEL_PSTATE
1061	select CPU_FREQ
1062	default y
1063	help
1064	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1065	  core ordering determined at manufacturing time, which allows
1066	  certain cores to reach higher turbo frequencies (when running
1067	  single threaded workloads) than others.
1068
1069	  Enabling this kernel feature teaches the scheduler about
1070	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1071	  scheduler's CPU selection logic accordingly, so that higher
1072	  overall system performance can be achieved.
1073
1074	  This feature will have no effect on CPUs without this feature.
1075
1076	  If unsure say Y here.
1077
1078config UP_LATE_INIT
1079	def_bool y
1080	depends on !SMP && X86_LOCAL_APIC
1081
1082config X86_UP_APIC
1083	bool "Local APIC support on uniprocessors" if !PCI_MSI
1084	default PCI_MSI
1085	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1086	help
1087	  A local APIC (Advanced Programmable Interrupt Controller) is an
1088	  integrated interrupt controller in the CPU. If you have a single-CPU
1089	  system which has a processor with a local APIC, you can say Y here to
1090	  enable and use it. If you say Y here even though your machine doesn't
1091	  have a local APIC, then the kernel will still run with no slowdown at
1092	  all. The local APIC supports CPU-generated self-interrupts (timer,
1093	  performance counters), and the NMI watchdog which detects hard
1094	  lockups.
1095
1096config X86_UP_IOAPIC
1097	bool "IO-APIC support on uniprocessors"
1098	depends on X86_UP_APIC
1099	help
1100	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1101	  SMP-capable replacement for PC-style interrupt controllers. Most
1102	  SMP systems and many recent uniprocessor systems have one.
1103
1104	  If you have a single-CPU system with an IO-APIC, you can say Y here
1105	  to use it. If you say Y here even though your machine doesn't have
1106	  an IO-APIC, then the kernel will still run with no slowdown at all.
1107
1108config X86_LOCAL_APIC
1109	def_bool y
1110	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1111	select IRQ_DOMAIN_HIERARCHY
1112
1113config X86_IO_APIC
1114	def_bool y
1115	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1116
1117config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1118	bool "Reroute for broken boot IRQs"
1119	depends on X86_IO_APIC
1120	help
1121	  This option enables a workaround that fixes a source of
1122	  spurious interrupts. This is recommended when threaded
1123	  interrupt handling is used on systems where the generation of
1124	  superfluous "boot interrupts" cannot be disabled.
1125
1126	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1127	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1128	  kernel does during interrupt handling). On chipsets where this
1129	  boot IRQ generation cannot be disabled, this workaround keeps
1130	  the original IRQ line masked so that only the equivalent "boot
1131	  IRQ" is delivered to the CPUs. The workaround also tells the
1132	  kernel to set up the IRQ handler on the boot IRQ line. In this
1133	  way only one interrupt is delivered to the kernel. Otherwise
1134	  the spurious second interrupt may cause the kernel to bring
1135	  down (vital) interrupt lines.
1136
1137	  Only affects "broken" chipsets. Interrupt sharing may be
1138	  increased on these systems.
1139
1140config X86_MCE
1141	bool "Machine Check / overheating reporting"
1142	select GENERIC_ALLOCATOR
1143	default y
1144	help
1145	  Machine Check support allows the processor to notify the
1146	  kernel if it detects a problem (e.g. overheating, data corruption).
1147	  The action the kernel takes depends on the severity of the problem,
1148	  ranging from warning messages to halting the machine.
1149
1150config X86_MCELOG_LEGACY
1151	bool "Support for deprecated /dev/mcelog character device"
1152	depends on X86_MCE
1153	help
1154	  Enable support for /dev/mcelog which is needed by the old mcelog
1155	  userspace logging daemon. Consider switching to the new generation
1156	  rasdaemon solution.
1157
1158config X86_MCE_INTEL
1159	def_bool y
1160	prompt "Intel MCE features"
1161	depends on X86_MCE && X86_LOCAL_APIC
1162	help
1163	  Additional support for intel specific MCE features such as
1164	  the thermal monitor.
1165
1166config X86_MCE_AMD
1167	def_bool y
1168	prompt "AMD MCE features"
1169	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1170	help
1171	  Additional support for AMD specific MCE features such as
1172	  the DRAM Error Threshold.
1173
1174config X86_ANCIENT_MCE
1175	bool "Support for old Pentium 5 / WinChip machine checks"
1176	depends on X86_32 && X86_MCE
1177	help
1178	  Include support for machine check handling on old Pentium 5 or WinChip
1179	  systems. These typically need to be enabled explicitly on the command
1180	  line.
1181
1182config X86_MCE_THRESHOLD
1183	depends on X86_MCE_AMD || X86_MCE_INTEL
1184	def_bool y
1185
1186config X86_MCE_INJECT
1187	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1188	tristate "Machine check injector support"
1189	help
1190	  Provide support for injecting machine checks for testing purposes.
1191	  If you don't know what a machine check is and you don't do kernel
1192	  QA it is safe to say n.
1193
1194source "arch/x86/events/Kconfig"
1195
1196config X86_LEGACY_VM86
1197	bool "Legacy VM86 support"
1198	depends on X86_32
1199	help
1200	  This option allows user programs to put the CPU into V8086
1201	  mode, which is an 80286-era approximation of 16-bit real mode.
1202
1203	  Some very old versions of X and/or vbetool require this option
1204	  for user mode setting.  Similarly, DOSEMU will use it if
1205	  available to accelerate real mode DOS programs.  However, any
1206	  recent version of DOSEMU, X, or vbetool should be fully
1207	  functional even without kernel VM86 support, as they will all
1208	  fall back to software emulation. Nevertheless, if you are using
1209	  a 16-bit DOS program where 16-bit performance matters, vm86
1210	  mode might be faster than emulation and you might want to
1211	  enable this option.
1212
1213	  Note that any app that works on a 64-bit kernel is unlikely to
1214	  need this option, as 64-bit kernels don't, and can't, support
1215	  V8086 mode. This option is also unrelated to 16-bit protected
1216	  mode and is not needed to run most 16-bit programs under Wine.
1217
1218	  Enabling this option increases the complexity of the kernel
1219	  and slows down exception handling a tiny bit.
1220
1221	  If unsure, say N here.
1222
1223config VM86
1224	bool
1225	default X86_LEGACY_VM86
1226
1227config X86_16BIT
1228	bool "Enable support for 16-bit segments" if EXPERT
1229	default y
1230	depends on MODIFY_LDT_SYSCALL
1231	help
1232	  This option is required by programs like Wine to run 16-bit
1233	  protected mode legacy code on x86 processors.  Disabling
1234	  this option saves about 300 bytes on i386, or around 6K text
1235	  plus 16K runtime memory on x86-64,
1236
1237config X86_ESPFIX32
1238	def_bool y
1239	depends on X86_16BIT && X86_32
1240
1241config X86_ESPFIX64
1242	def_bool y
1243	depends on X86_16BIT && X86_64
1244
1245config X86_VSYSCALL_EMULATION
1246	bool "Enable vsyscall emulation" if EXPERT
1247	default y
1248	depends on X86_64
1249	help
1250	  This enables emulation of the legacy vsyscall page.  Disabling
1251	  it is roughly equivalent to booting with vsyscall=none, except
1252	  that it will also disable the helpful warning if a program
1253	  tries to use a vsyscall.  With this option set to N, offending
1254	  programs will just segfault, citing addresses of the form
1255	  0xffffffffff600?00.
1256
1257	  This option is required by many programs built before 2013, and
1258	  care should be used even with newer programs if set to N.
1259
1260	  Disabling this option saves about 7K of kernel size and
1261	  possibly 4K of additional runtime pagetable memory.
1262
1263config X86_IOPL_IOPERM
1264	bool "IOPERM and IOPL Emulation"
1265	default y
1266	help
1267	  This enables the ioperm() and iopl() syscalls which are necessary
1268	  for legacy applications.
1269
1270	  Legacy IOPL support is an overbroad mechanism which allows user
1271	  space aside of accessing all 65536 I/O ports also to disable
1272	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1273	  capabilities and permission from potentially active security
1274	  modules.
1275
1276	  The emulation restricts the functionality of the syscall to
1277	  only allowing the full range I/O port access, but prevents the
1278	  ability to disable interrupts from user space which would be
1279	  granted if the hardware IOPL mechanism would be used.
1280
1281config TOSHIBA
1282	tristate "Toshiba Laptop support"
1283	depends on X86_32
1284	help
1285	  This adds a driver to safely access the System Management Mode of
1286	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1287	  not work on models with a Phoenix BIOS. The System Management Mode
1288	  is used to set the BIOS and power saving options on Toshiba portables.
1289
1290	  For information on utilities to make use of this driver see the
1291	  Toshiba Linux utilities web site at:
1292	  <http://www.buzzard.org.uk/toshiba/>.
1293
1294	  Say Y if you intend to run this kernel on a Toshiba portable.
1295	  Say N otherwise.
1296
1297config X86_REBOOTFIXUPS
1298	bool "Enable X86 board specific fixups for reboot"
1299	depends on X86_32
1300	help
1301	  This enables chipset and/or board specific fixups to be done
1302	  in order to get reboot to work correctly. This is only needed on
1303	  some combinations of hardware and BIOS. The symptom, for which
1304	  this config is intended, is when reboot ends with a stalled/hung
1305	  system.
1306
1307	  Currently, the only fixup is for the Geode machines using
1308	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1309
1310	  Say Y if you want to enable the fixup. Currently, it's safe to
1311	  enable this option even if you don't need it.
1312	  Say N otherwise.
1313
1314config MICROCODE
1315	bool "CPU microcode loading support"
1316	default y
1317	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1318	help
1319	  If you say Y here, you will be able to update the microcode on
1320	  Intel and AMD processors. The Intel support is for the IA32 family,
1321	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1322	  AMD support is for families 0x10 and later. You will obviously need
1323	  the actual microcode binary data itself which is not shipped with
1324	  the Linux kernel.
1325
1326	  The preferred method to load microcode from a detached initrd is described
1327	  in Documentation/x86/microcode.rst. For that you need to enable
1328	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1329	  initrd for microcode blobs.
1330
1331	  In addition, you can build the microcode into the kernel. For that you
1332	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1333	  config option.
1334
1335config MICROCODE_INTEL
1336	bool "Intel microcode loading support"
1337	depends on CPU_SUP_INTEL && MICROCODE
1338	default MICROCODE
1339	help
1340	  This options enables microcode patch loading support for Intel
1341	  processors.
1342
1343	  For the current Intel microcode data package go to
1344	  <https://downloadcenter.intel.com> and search for
1345	  'Linux Processor Microcode Data File'.
1346
1347config MICROCODE_AMD
1348	bool "AMD microcode loading support"
1349	depends on CPU_SUP_AMD && MICROCODE
1350	help
1351	  If you select this option, microcode patch loading support for AMD
1352	  processors will be enabled.
1353
1354config MICROCODE_LATE_LOADING
1355	bool "Late microcode loading (DANGEROUS)"
1356	default n
1357	depends on MICROCODE
1358	help
1359	  Loading microcode late, when the system is up and executing instructions
1360	  is a tricky business and should be avoided if possible. Just the sequence
1361	  of synchronizing all cores and SMT threads is one fragile dance which does
1362	  not guarantee that cores might not softlock after the loading. Therefore,
1363	  use this at your own risk. Late loading taints the kernel too.
1364
1365config X86_MSR
1366	tristate "/dev/cpu/*/msr - Model-specific register support"
1367	help
1368	  This device gives privileged processes access to the x86
1369	  Model-Specific Registers (MSRs).  It is a character device with
1370	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1371	  MSR accesses are directed to a specific CPU on multi-processor
1372	  systems.
1373
1374config X86_CPUID
1375	tristate "/dev/cpu/*/cpuid - CPU information support"
1376	help
1377	  This device gives processes access to the x86 CPUID instruction to
1378	  be executed on a specific processor.  It is a character device
1379	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1380	  /dev/cpu/31/cpuid.
1381
1382choice
1383	prompt "High Memory Support"
1384	default HIGHMEM4G
1385	depends on X86_32
1386
1387config NOHIGHMEM
1388	bool "off"
1389	help
1390	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1391	  However, the address space of 32-bit x86 processors is only 4
1392	  Gigabytes large. That means that, if you have a large amount of
1393	  physical memory, not all of it can be "permanently mapped" by the
1394	  kernel. The physical memory that's not permanently mapped is called
1395	  "high memory".
1396
1397	  If you are compiling a kernel which will never run on a machine with
1398	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1399	  choice and suitable for most users). This will result in a "3GB/1GB"
1400	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1401	  space and the remaining part of the 4GB virtual memory space is used
1402	  by the kernel to permanently map as much physical memory as
1403	  possible.
1404
1405	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1406	  answer "4GB" here.
1407
1408	  If more than 4 Gigabytes is used then answer "64GB" here. This
1409	  selection turns Intel PAE (Physical Address Extension) mode on.
1410	  PAE implements 3-level paging on IA32 processors. PAE is fully
1411	  supported by Linux, PAE mode is implemented on all recent Intel
1412	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1413	  then the kernel will not boot on CPUs that don't support PAE!
1414
1415	  The actual amount of total physical memory will either be
1416	  auto detected or can be forced by using a kernel command line option
1417	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1418	  your boot loader (lilo or loadlin) about how to pass options to the
1419	  kernel at boot time.)
1420
1421	  If unsure, say "off".
1422
1423config HIGHMEM4G
1424	bool "4GB"
1425	help
1426	  Select this if you have a 32-bit processor and between 1 and 4
1427	  gigabytes of physical RAM.
1428
1429config HIGHMEM64G
1430	bool "64GB"
1431	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1432	select X86_PAE
1433	help
1434	  Select this if you have a 32-bit processor and more than 4
1435	  gigabytes of physical RAM.
1436
1437endchoice
1438
1439choice
1440	prompt "Memory split" if EXPERT
1441	default VMSPLIT_3G
1442	depends on X86_32
1443	help
1444	  Select the desired split between kernel and user memory.
1445
1446	  If the address range available to the kernel is less than the
1447	  physical memory installed, the remaining memory will be available
1448	  as "high memory". Accessing high memory is a little more costly
1449	  than low memory, as it needs to be mapped into the kernel first.
1450	  Note that increasing the kernel address space limits the range
1451	  available to user programs, making the address space there
1452	  tighter.  Selecting anything other than the default 3G/1G split
1453	  will also likely make your kernel incompatible with binary-only
1454	  kernel modules.
1455
1456	  If you are not absolutely sure what you are doing, leave this
1457	  option alone!
1458
1459	config VMSPLIT_3G
1460		bool "3G/1G user/kernel split"
1461	config VMSPLIT_3G_OPT
1462		depends on !X86_PAE
1463		bool "3G/1G user/kernel split (for full 1G low memory)"
1464	config VMSPLIT_2G
1465		bool "2G/2G user/kernel split"
1466	config VMSPLIT_2G_OPT
1467		depends on !X86_PAE
1468		bool "2G/2G user/kernel split (for full 2G low memory)"
1469	config VMSPLIT_1G
1470		bool "1G/3G user/kernel split"
1471endchoice
1472
1473config PAGE_OFFSET
1474	hex
1475	default 0xB0000000 if VMSPLIT_3G_OPT
1476	default 0x80000000 if VMSPLIT_2G
1477	default 0x78000000 if VMSPLIT_2G_OPT
1478	default 0x40000000 if VMSPLIT_1G
1479	default 0xC0000000
1480	depends on X86_32
1481
1482config HIGHMEM
1483	def_bool y
1484	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1485
1486config X86_PAE
1487	bool "PAE (Physical Address Extension) Support"
1488	depends on X86_32 && !HIGHMEM4G
1489	select PHYS_ADDR_T_64BIT
1490	select SWIOTLB
1491	help
1492	  PAE is required for NX support, and furthermore enables
1493	  larger swapspace support for non-overcommit purposes. It
1494	  has the cost of more pagetable lookup overhead, and also
1495	  consumes more pagetable space per process.
1496
1497config X86_5LEVEL
1498	bool "Enable 5-level page tables support"
1499	default y
1500	select DYNAMIC_MEMORY_LAYOUT
1501	select SPARSEMEM_VMEMMAP
1502	depends on X86_64
1503	help
1504	  5-level paging enables access to larger address space:
1505	  upto 128 PiB of virtual address space and 4 PiB of
1506	  physical address space.
1507
1508	  It will be supported by future Intel CPUs.
1509
1510	  A kernel with the option enabled can be booted on machines that
1511	  support 4- or 5-level paging.
1512
1513	  See Documentation/x86/x86_64/5level-paging.rst for more
1514	  information.
1515
1516	  Say N if unsure.
1517
1518config X86_DIRECT_GBPAGES
1519	def_bool y
1520	depends on X86_64
1521	help
1522	  Certain kernel features effectively disable kernel
1523	  linear 1 GB mappings (even if the CPU otherwise
1524	  supports them), so don't confuse the user by printing
1525	  that we have them enabled.
1526
1527config X86_CPA_STATISTICS
1528	bool "Enable statistic for Change Page Attribute"
1529	depends on DEBUG_FS
1530	help
1531	  Expose statistics about the Change Page Attribute mechanism, which
1532	  helps to determine the effectiveness of preserving large and huge
1533	  page mappings when mapping protections are changed.
1534
1535config X86_MEM_ENCRYPT
1536	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1537	select DYNAMIC_PHYSICAL_MASK
1538	def_bool n
1539
1540config AMD_MEM_ENCRYPT
1541	bool "AMD Secure Memory Encryption (SME) support"
1542	depends on X86_64 && CPU_SUP_AMD
1543	select DMA_COHERENT_POOL
1544	select ARCH_USE_MEMREMAP_PROT
1545	select INSTRUCTION_DECODER
1546	select ARCH_HAS_CC_PLATFORM
1547	select X86_MEM_ENCRYPT
1548	help
1549	  Say yes to enable support for the encryption of system memory.
1550	  This requires an AMD processor that supports Secure Memory
1551	  Encryption (SME).
1552
1553config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1554	bool "Activate AMD Secure Memory Encryption (SME) by default"
1555	depends on AMD_MEM_ENCRYPT
1556	help
1557	  Say yes to have system memory encrypted by default if running on
1558	  an AMD processor that supports Secure Memory Encryption (SME).
1559
1560	  If set to Y, then the encryption of system memory can be
1561	  deactivated with the mem_encrypt=off command line option.
1562
1563	  If set to N, then the encryption of system memory can be
1564	  activated with the mem_encrypt=on command line option.
1565
1566# Common NUMA Features
1567config NUMA
1568	bool "NUMA Memory Allocation and Scheduler Support"
1569	depends on SMP
1570	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1571	default y if X86_BIGSMP
1572	select USE_PERCPU_NUMA_NODE_ID
1573	help
1574	  Enable NUMA (Non-Uniform Memory Access) support.
1575
1576	  The kernel will try to allocate memory used by a CPU on the
1577	  local memory controller of the CPU and add some more
1578	  NUMA awareness to the kernel.
1579
1580	  For 64-bit this is recommended if the system is Intel Core i7
1581	  (or later), AMD Opteron, or EM64T NUMA.
1582
1583	  For 32-bit this is only needed if you boot a 32-bit
1584	  kernel on a 64-bit NUMA platform.
1585
1586	  Otherwise, you should say N.
1587
1588config AMD_NUMA
1589	def_bool y
1590	prompt "Old style AMD Opteron NUMA detection"
1591	depends on X86_64 && NUMA && PCI
1592	help
1593	  Enable AMD NUMA node topology detection.  You should say Y here if
1594	  you have a multi processor AMD system. This uses an old method to
1595	  read the NUMA configuration directly from the builtin Northbridge
1596	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1597	  which also takes priority if both are compiled in.
1598
1599config X86_64_ACPI_NUMA
1600	def_bool y
1601	prompt "ACPI NUMA detection"
1602	depends on X86_64 && NUMA && ACPI && PCI
1603	select ACPI_NUMA
1604	help
1605	  Enable ACPI SRAT based node topology detection.
1606
1607config NUMA_EMU
1608	bool "NUMA emulation"
1609	depends on NUMA
1610	help
1611	  Enable NUMA emulation. A flat machine will be split
1612	  into virtual nodes when booted with "numa=fake=N", where N is the
1613	  number of nodes. This is only useful for debugging.
1614
1615config NODES_SHIFT
1616	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1617	range 1 10
1618	default "10" if MAXSMP
1619	default "6" if X86_64
1620	default "3"
1621	depends on NUMA
1622	help
1623	  Specify the maximum number of NUMA Nodes available on the target
1624	  system.  Increases memory reserved to accommodate various tables.
1625
1626config ARCH_FLATMEM_ENABLE
1627	def_bool y
1628	depends on X86_32 && !NUMA
1629
1630config ARCH_SPARSEMEM_ENABLE
1631	def_bool y
1632	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1633	select SPARSEMEM_STATIC if X86_32
1634	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1635
1636config ARCH_SPARSEMEM_DEFAULT
1637	def_bool X86_64 || (NUMA && X86_32)
1638
1639config ARCH_SELECT_MEMORY_MODEL
1640	def_bool y
1641	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1642
1643config ARCH_MEMORY_PROBE
1644	bool "Enable sysfs memory/probe interface"
1645	depends on MEMORY_HOTPLUG
1646	help
1647	  This option enables a sysfs memory/probe interface for testing.
1648	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1649	  If you are unsure how to answer this question, answer N.
1650
1651config ARCH_PROC_KCORE_TEXT
1652	def_bool y
1653	depends on X86_64 && PROC_KCORE
1654
1655config ILLEGAL_POINTER_VALUE
1656	hex
1657	default 0 if X86_32
1658	default 0xdead000000000000 if X86_64
1659
1660config X86_PMEM_LEGACY_DEVICE
1661	bool
1662
1663config X86_PMEM_LEGACY
1664	tristate "Support non-standard NVDIMMs and ADR protected memory"
1665	depends on PHYS_ADDR_T_64BIT
1666	depends on BLK_DEV
1667	select X86_PMEM_LEGACY_DEVICE
1668	select NUMA_KEEP_MEMINFO if NUMA
1669	select LIBNVDIMM
1670	help
1671	  Treat memory marked using the non-standard e820 type of 12 as used
1672	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1673	  The kernel will offer these regions to the 'pmem' driver so
1674	  they can be used for persistent storage.
1675
1676	  Say Y if unsure.
1677
1678config HIGHPTE
1679	bool "Allocate 3rd-level pagetables from highmem"
1680	depends on HIGHMEM
1681	help
1682	  The VM uses one page table entry for each page of physical memory.
1683	  For systems with a lot of RAM, this can be wasteful of precious
1684	  low memory.  Setting this option will put user-space page table
1685	  entries in high memory.
1686
1687config X86_CHECK_BIOS_CORRUPTION
1688	bool "Check for low memory corruption"
1689	help
1690	  Periodically check for memory corruption in low memory, which
1691	  is suspected to be caused by BIOS.  Even when enabled in the
1692	  configuration, it is disabled at runtime.  Enable it by
1693	  setting "memory_corruption_check=1" on the kernel command
1694	  line.  By default it scans the low 64k of memory every 60
1695	  seconds; see the memory_corruption_check_size and
1696	  memory_corruption_check_period parameters in
1697	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1698
1699	  When enabled with the default parameters, this option has
1700	  almost no overhead, as it reserves a relatively small amount
1701	  of memory and scans it infrequently.  It both detects corruption
1702	  and prevents it from affecting the running system.
1703
1704	  It is, however, intended as a diagnostic tool; if repeatable
1705	  BIOS-originated corruption always affects the same memory,
1706	  you can use memmap= to prevent the kernel from using that
1707	  memory.
1708
1709config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1710	bool "Set the default setting of memory_corruption_check"
1711	depends on X86_CHECK_BIOS_CORRUPTION
1712	default y
1713	help
1714	  Set whether the default state of memory_corruption_check is
1715	  on or off.
1716
1717config MATH_EMULATION
1718	bool
1719	depends on MODIFY_LDT_SYSCALL
1720	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1721	help
1722	  Linux can emulate a math coprocessor (used for floating point
1723	  operations) if you don't have one. 486DX and Pentium processors have
1724	  a math coprocessor built in, 486SX and 386 do not, unless you added
1725	  a 487DX or 387, respectively. (The messages during boot time can
1726	  give you some hints here ["man dmesg"].) Everyone needs either a
1727	  coprocessor or this emulation.
1728
1729	  If you don't have a math coprocessor, you need to say Y here; if you
1730	  say Y here even though you have a coprocessor, the coprocessor will
1731	  be used nevertheless. (This behavior can be changed with the kernel
1732	  command line option "no387", which comes handy if your coprocessor
1733	  is broken. Try "man bootparam" or see the documentation of your boot
1734	  loader (lilo or loadlin) about how to pass options to the kernel at
1735	  boot time.) This means that it is a good idea to say Y here if you
1736	  intend to use this kernel on different machines.
1737
1738	  More information about the internals of the Linux math coprocessor
1739	  emulation can be found in <file:arch/x86/math-emu/README>.
1740
1741	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1742	  kernel, it won't hurt.
1743
1744config MTRR
1745	def_bool y
1746	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1747	help
1748	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1749	  the Memory Type Range Registers (MTRRs) may be used to control
1750	  processor access to memory ranges. This is most useful if you have
1751	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1752	  allows bus write transfers to be combined into a larger transfer
1753	  before bursting over the PCI/AGP bus. This can increase performance
1754	  of image write operations 2.5 times or more. Saying Y here creates a
1755	  /proc/mtrr file which may be used to manipulate your processor's
1756	  MTRRs. Typically the X server should use this.
1757
1758	  This code has a reasonably generic interface so that similar
1759	  control registers on other processors can be easily supported
1760	  as well:
1761
1762	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1763	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1764	  these, the ARRs are used to emulate the MTRRs.
1765	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1766	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1767	  write-combining. All of these processors are supported by this code
1768	  and it makes sense to say Y here if you have one of them.
1769
1770	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1771	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1772	  can lead to all sorts of problems, so it's good to say Y here.
1773
1774	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1775	  just add about 9 KB to your kernel.
1776
1777	  See <file:Documentation/x86/mtrr.rst> for more information.
1778
1779config MTRR_SANITIZER
1780	def_bool y
1781	prompt "MTRR cleanup support"
1782	depends on MTRR
1783	help
1784	  Convert MTRR layout from continuous to discrete, so X drivers can
1785	  add writeback entries.
1786
1787	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1788	  The largest mtrr entry size for a continuous block can be set with
1789	  mtrr_chunk_size.
1790
1791	  If unsure, say Y.
1792
1793config MTRR_SANITIZER_ENABLE_DEFAULT
1794	int "MTRR cleanup enable value (0-1)"
1795	range 0 1
1796	default "0"
1797	depends on MTRR_SANITIZER
1798	help
1799	  Enable mtrr cleanup default value
1800
1801config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1802	int "MTRR cleanup spare reg num (0-7)"
1803	range 0 7
1804	default "1"
1805	depends on MTRR_SANITIZER
1806	help
1807	  mtrr cleanup spare entries default, it can be changed via
1808	  mtrr_spare_reg_nr=N on the kernel command line.
1809
1810config X86_PAT
1811	def_bool y
1812	prompt "x86 PAT support" if EXPERT
1813	depends on MTRR
1814	help
1815	  Use PAT attributes to setup page level cache control.
1816
1817	  PATs are the modern equivalents of MTRRs and are much more
1818	  flexible than MTRRs.
1819
1820	  Say N here if you see bootup problems (boot crash, boot hang,
1821	  spontaneous reboots) or a non-working video driver.
1822
1823	  If unsure, say Y.
1824
1825config ARCH_USES_PG_UNCACHED
1826	def_bool y
1827	depends on X86_PAT
1828
1829config X86_UMIP
1830	def_bool y
1831	prompt "User Mode Instruction Prevention" if EXPERT
1832	help
1833	  User Mode Instruction Prevention (UMIP) is a security feature in
1834	  some x86 processors. If enabled, a general protection fault is
1835	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1836	  executed in user mode. These instructions unnecessarily expose
1837	  information about the hardware state.
1838
1839	  The vast majority of applications do not use these instructions.
1840	  For the very few that do, software emulation is provided in
1841	  specific cases in protected and virtual-8086 modes. Emulated
1842	  results are dummy.
1843
1844config CC_HAS_IBT
1845	# GCC >= 9 and binutils >= 2.29
1846	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1847	# Clang/LLVM >= 14
1848	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1849	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1850	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1851		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1852		  $(as-instr,endbr64)
1853
1854config X86_KERNEL_IBT
1855	prompt "Indirect Branch Tracking"
1856	bool
1857	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1858	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1859	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1860	select OBJTOOL
1861	help
1862	  Build the kernel with support for Indirect Branch Tracking, a
1863	  hardware support course-grain forward-edge Control Flow Integrity
1864	  protection. It enforces that all indirect calls must land on
1865	  an ENDBR instruction, as such, the compiler will instrument the
1866	  code with them to make this happen.
1867
1868	  In addition to building the kernel with IBT, seal all functions that
1869	  are not indirect call targets, avoiding them ever becoming one.
1870
1871	  This requires LTO like objtool runs and will slow down the build. It
1872	  does significantly reduce the number of ENDBR instructions in the
1873	  kernel image.
1874
1875config X86_INTEL_MEMORY_PROTECTION_KEYS
1876	prompt "Memory Protection Keys"
1877	def_bool y
1878	# Note: only available in 64-bit mode
1879	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1880	select ARCH_USES_HIGH_VMA_FLAGS
1881	select ARCH_HAS_PKEYS
1882	help
1883	  Memory Protection Keys provides a mechanism for enforcing
1884	  page-based protections, but without requiring modification of the
1885	  page tables when an application changes protection domains.
1886
1887	  For details, see Documentation/core-api/protection-keys.rst
1888
1889	  If unsure, say y.
1890
1891choice
1892	prompt "TSX enable mode"
1893	depends on CPU_SUP_INTEL
1894	default X86_INTEL_TSX_MODE_OFF
1895	help
1896	  Intel's TSX (Transactional Synchronization Extensions) feature
1897	  allows to optimize locking protocols through lock elision which
1898	  can lead to a noticeable performance boost.
1899
1900	  On the other hand it has been shown that TSX can be exploited
1901	  to form side channel attacks (e.g. TAA) and chances are there
1902	  will be more of those attacks discovered in the future.
1903
1904	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1905	  might override this decision by tsx=on the command line parameter.
1906	  Even with TSX enabled, the kernel will attempt to enable the best
1907	  possible TAA mitigation setting depending on the microcode available
1908	  for the particular machine.
1909
1910	  This option allows to set the default tsx mode between tsx=on, =off
1911	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1912	  details.
1913
1914	  Say off if not sure, auto if TSX is in use but it should be used on safe
1915	  platforms or on if TSX is in use and the security aspect of tsx is not
1916	  relevant.
1917
1918config X86_INTEL_TSX_MODE_OFF
1919	bool "off"
1920	help
1921	  TSX is disabled if possible - equals to tsx=off command line parameter.
1922
1923config X86_INTEL_TSX_MODE_ON
1924	bool "on"
1925	help
1926	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1927	  line parameter.
1928
1929config X86_INTEL_TSX_MODE_AUTO
1930	bool "auto"
1931	help
1932	  TSX is enabled on TSX capable HW that is believed to be safe against
1933	  side channel attacks- equals the tsx=auto command line parameter.
1934endchoice
1935
1936config X86_SGX
1937	bool "Software Guard eXtensions (SGX)"
1938	depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1939	depends on CRYPTO=y
1940	depends on CRYPTO_SHA256=y
1941	select SRCU
1942	select MMU_NOTIFIER
1943	select NUMA_KEEP_MEMINFO if NUMA
1944	select XARRAY_MULTI
1945	help
1946	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1947	  that can be used by applications to set aside private regions of code
1948	  and data, referred to as enclaves. An enclave's private memory can
1949	  only be accessed by code running within the enclave. Accesses from
1950	  outside the enclave, including other enclaves, are disallowed by
1951	  hardware.
1952
1953	  If unsure, say N.
1954
1955config EFI
1956	bool "EFI runtime service support"
1957	depends on ACPI
1958	select UCS2_STRING
1959	select EFI_RUNTIME_WRAPPERS
1960	select ARCH_USE_MEMREMAP_PROT
1961	help
1962	  This enables the kernel to use EFI runtime services that are
1963	  available (such as the EFI variable services).
1964
1965	  This option is only useful on systems that have EFI firmware.
1966	  In addition, you should use the latest ELILO loader available
1967	  at <http://elilo.sourceforge.net> in order to take advantage
1968	  of EFI runtime services. However, even with this option, the
1969	  resultant kernel should continue to boot on existing non-EFI
1970	  platforms.
1971
1972config EFI_STUB
1973	bool "EFI stub support"
1974	depends on EFI
1975	select RELOCATABLE
1976	help
1977	  This kernel feature allows a bzImage to be loaded directly
1978	  by EFI firmware without the use of a bootloader.
1979
1980	  See Documentation/admin-guide/efi-stub.rst for more information.
1981
1982config EFI_MIXED
1983	bool "EFI mixed-mode support"
1984	depends on EFI_STUB && X86_64
1985	help
1986	  Enabling this feature allows a 64-bit kernel to be booted
1987	  on a 32-bit firmware, provided that your CPU supports 64-bit
1988	  mode.
1989
1990	  Note that it is not possible to boot a mixed-mode enabled
1991	  kernel via the EFI boot stub - a bootloader that supports
1992	  the EFI handover protocol must be used.
1993
1994	  If unsure, say N.
1995
1996source "kernel/Kconfig.hz"
1997
1998config KEXEC
1999	bool "kexec system call"
2000	select KEXEC_CORE
2001	help
2002	  kexec is a system call that implements the ability to shutdown your
2003	  current kernel, and to start another kernel.  It is like a reboot
2004	  but it is independent of the system firmware.   And like a reboot
2005	  you can start any kernel with it, not just Linux.
2006
2007	  The name comes from the similarity to the exec system call.
2008
2009	  It is an ongoing process to be certain the hardware in a machine
2010	  is properly shutdown, so do not be surprised if this code does not
2011	  initially work for you.  As of this writing the exact hardware
2012	  interface is strongly in flux, so no good recommendation can be
2013	  made.
2014
2015config KEXEC_FILE
2016	bool "kexec file based system call"
2017	select KEXEC_CORE
2018	select HAVE_IMA_KEXEC if IMA
2019	depends on X86_64
2020	depends on CRYPTO=y
2021	depends on CRYPTO_SHA256=y
2022	help
2023	  This is new version of kexec system call. This system call is
2024	  file based and takes file descriptors as system call argument
2025	  for kernel and initramfs as opposed to list of segments as
2026	  accepted by previous system call.
2027
2028config ARCH_HAS_KEXEC_PURGATORY
2029	def_bool KEXEC_FILE
2030
2031config KEXEC_SIG
2032	bool "Verify kernel signature during kexec_file_load() syscall"
2033	depends on KEXEC_FILE
2034	help
2035
2036	  This option makes the kexec_file_load() syscall check for a valid
2037	  signature of the kernel image.  The image can still be loaded without
2038	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2039	  there's a signature that we can check, then it must be valid.
2040
2041	  In addition to this option, you need to enable signature
2042	  verification for the corresponding kernel image type being
2043	  loaded in order for this to work.
2044
2045config KEXEC_SIG_FORCE
2046	bool "Require a valid signature in kexec_file_load() syscall"
2047	depends on KEXEC_SIG
2048	help
2049	  This option makes kernel signature verification mandatory for
2050	  the kexec_file_load() syscall.
2051
2052config KEXEC_BZIMAGE_VERIFY_SIG
2053	bool "Enable bzImage signature verification support"
2054	depends on KEXEC_SIG
2055	depends on SIGNED_PE_FILE_VERIFICATION
2056	select SYSTEM_TRUSTED_KEYRING
2057	help
2058	  Enable bzImage signature verification support.
2059
2060config CRASH_DUMP
2061	bool "kernel crash dumps"
2062	depends on X86_64 || (X86_32 && HIGHMEM)
2063	help
2064	  Generate crash dump after being started by kexec.
2065	  This should be normally only set in special crash dump kernels
2066	  which are loaded in the main kernel with kexec-tools into
2067	  a specially reserved region and then later executed after
2068	  a crash by kdump/kexec. The crash dump kernel must be compiled
2069	  to a memory address not used by the main kernel or BIOS using
2070	  PHYSICAL_START, or it must be built as a relocatable image
2071	  (CONFIG_RELOCATABLE=y).
2072	  For more details see Documentation/admin-guide/kdump/kdump.rst
2073
2074config KEXEC_JUMP
2075	bool "kexec jump"
2076	depends on KEXEC && HIBERNATION
2077	help
2078	  Jump between original kernel and kexeced kernel and invoke
2079	  code in physical address mode via KEXEC
2080
2081config PHYSICAL_START
2082	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2083	default "0x1000000"
2084	help
2085	  This gives the physical address where the kernel is loaded.
2086
2087	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2088	  bzImage will decompress itself to above physical address and
2089	  run from there. Otherwise, bzImage will run from the address where
2090	  it has been loaded by the boot loader and will ignore above physical
2091	  address.
2092
2093	  In normal kdump cases one does not have to set/change this option
2094	  as now bzImage can be compiled as a completely relocatable image
2095	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2096	  address. This option is mainly useful for the folks who don't want
2097	  to use a bzImage for capturing the crash dump and want to use a
2098	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2099	  to be specifically compiled to run from a specific memory area
2100	  (normally a reserved region) and this option comes handy.
2101
2102	  So if you are using bzImage for capturing the crash dump,
2103	  leave the value here unchanged to 0x1000000 and set
2104	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2105	  for capturing the crash dump change this value to start of
2106	  the reserved region.  In other words, it can be set based on
2107	  the "X" value as specified in the "crashkernel=YM@XM"
2108	  command line boot parameter passed to the panic-ed
2109	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2110	  for more details about crash dumps.
2111
2112	  Usage of bzImage for capturing the crash dump is recommended as
2113	  one does not have to build two kernels. Same kernel can be used
2114	  as production kernel and capture kernel. Above option should have
2115	  gone away after relocatable bzImage support is introduced. But it
2116	  is present because there are users out there who continue to use
2117	  vmlinux for dump capture. This option should go away down the
2118	  line.
2119
2120	  Don't change this unless you know what you are doing.
2121
2122config RELOCATABLE
2123	bool "Build a relocatable kernel"
2124	default y
2125	help
2126	  This builds a kernel image that retains relocation information
2127	  so it can be loaded someplace besides the default 1MB.
2128	  The relocations tend to make the kernel binary about 10% larger,
2129	  but are discarded at runtime.
2130
2131	  One use is for the kexec on panic case where the recovery kernel
2132	  must live at a different physical address than the primary
2133	  kernel.
2134
2135	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2136	  it has been loaded at and the compile time physical address
2137	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2138
2139config RANDOMIZE_BASE
2140	bool "Randomize the address of the kernel image (KASLR)"
2141	depends on RELOCATABLE
2142	default y
2143	help
2144	  In support of Kernel Address Space Layout Randomization (KASLR),
2145	  this randomizes the physical address at which the kernel image
2146	  is decompressed and the virtual address where the kernel
2147	  image is mapped, as a security feature that deters exploit
2148	  attempts relying on knowledge of the location of kernel
2149	  code internals.
2150
2151	  On 64-bit, the kernel physical and virtual addresses are
2152	  randomized separately. The physical address will be anywhere
2153	  between 16MB and the top of physical memory (up to 64TB). The
2154	  virtual address will be randomized from 16MB up to 1GB (9 bits
2155	  of entropy). Note that this also reduces the memory space
2156	  available to kernel modules from 1.5GB to 1GB.
2157
2158	  On 32-bit, the kernel physical and virtual addresses are
2159	  randomized together. They will be randomized from 16MB up to
2160	  512MB (8 bits of entropy).
2161
2162	  Entropy is generated using the RDRAND instruction if it is
2163	  supported. If RDTSC is supported, its value is mixed into
2164	  the entropy pool as well. If neither RDRAND nor RDTSC are
2165	  supported, then entropy is read from the i8254 timer. The
2166	  usable entropy is limited by the kernel being built using
2167	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2168	  minimum of 2MB. As a result, only 10 bits of entropy are
2169	  theoretically possible, but the implementations are further
2170	  limited due to memory layouts.
2171
2172	  If unsure, say Y.
2173
2174# Relocation on x86 needs some additional build support
2175config X86_NEED_RELOCS
2176	def_bool y
2177	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2178
2179config PHYSICAL_ALIGN
2180	hex "Alignment value to which kernel should be aligned"
2181	default "0x200000"
2182	range 0x2000 0x1000000 if X86_32
2183	range 0x200000 0x1000000 if X86_64
2184	help
2185	  This value puts the alignment restrictions on physical address
2186	  where kernel is loaded and run from. Kernel is compiled for an
2187	  address which meets above alignment restriction.
2188
2189	  If bootloader loads the kernel at a non-aligned address and
2190	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2191	  address aligned to above value and run from there.
2192
2193	  If bootloader loads the kernel at a non-aligned address and
2194	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2195	  load address and decompress itself to the address it has been
2196	  compiled for and run from there. The address for which kernel is
2197	  compiled already meets above alignment restrictions. Hence the
2198	  end result is that kernel runs from a physical address meeting
2199	  above alignment restrictions.
2200
2201	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2202	  this value must be a multiple of 0x200000.
2203
2204	  Don't change this unless you know what you are doing.
2205
2206config DYNAMIC_MEMORY_LAYOUT
2207	bool
2208	help
2209	  This option makes base addresses of vmalloc and vmemmap as well as
2210	  __PAGE_OFFSET movable during boot.
2211
2212config RANDOMIZE_MEMORY
2213	bool "Randomize the kernel memory sections"
2214	depends on X86_64
2215	depends on RANDOMIZE_BASE
2216	select DYNAMIC_MEMORY_LAYOUT
2217	default RANDOMIZE_BASE
2218	help
2219	  Randomizes the base virtual address of kernel memory sections
2220	  (physical memory mapping, vmalloc & vmemmap). This security feature
2221	  makes exploits relying on predictable memory locations less reliable.
2222
2223	  The order of allocations remains unchanged. Entropy is generated in
2224	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2225	  configuration have in average 30,000 different possible virtual
2226	  addresses for each memory section.
2227
2228	  If unsure, say Y.
2229
2230config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2231	hex "Physical memory mapping padding" if EXPERT
2232	depends on RANDOMIZE_MEMORY
2233	default "0xa" if MEMORY_HOTPLUG
2234	default "0x0"
2235	range 0x1 0x40 if MEMORY_HOTPLUG
2236	range 0x0 0x40
2237	help
2238	  Define the padding in terabytes added to the existing physical
2239	  memory size during kernel memory randomization. It is useful
2240	  for memory hotplug support but reduces the entropy available for
2241	  address randomization.
2242
2243	  If unsure, leave at the default value.
2244
2245config HOTPLUG_CPU
2246	def_bool y
2247	depends on SMP
2248
2249config BOOTPARAM_HOTPLUG_CPU0
2250	bool "Set default setting of cpu0_hotpluggable"
2251	depends on HOTPLUG_CPU
2252	help
2253	  Set whether default state of cpu0_hotpluggable is on or off.
2254
2255	  Say Y here to enable CPU0 hotplug by default. If this switch
2256	  is turned on, there is no need to give cpu0_hotplug kernel
2257	  parameter and the CPU0 hotplug feature is enabled by default.
2258
2259	  Please note: there are two known CPU0 dependencies if you want
2260	  to enable the CPU0 hotplug feature either by this switch or by
2261	  cpu0_hotplug kernel parameter.
2262
2263	  First, resume from hibernate or suspend always starts from CPU0.
2264	  So hibernate and suspend are prevented if CPU0 is offline.
2265
2266	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2267	  offline if any interrupt can not migrate out of CPU0. There may
2268	  be other CPU0 dependencies.
2269
2270	  Please make sure the dependencies are under your control before
2271	  you enable this feature.
2272
2273	  Say N if you don't want to enable CPU0 hotplug feature by default.
2274	  You still can enable the CPU0 hotplug feature at boot by kernel
2275	  parameter cpu0_hotplug.
2276
2277config DEBUG_HOTPLUG_CPU0
2278	def_bool n
2279	prompt "Debug CPU0 hotplug"
2280	depends on HOTPLUG_CPU
2281	help
2282	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2283	  soon as possible and boots up userspace with CPU0 offlined. User
2284	  can online CPU0 back after boot time.
2285
2286	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2287	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2288	  compilation or giving cpu0_hotplug kernel parameter at boot.
2289
2290	  If unsure, say N.
2291
2292config COMPAT_VDSO
2293	def_bool n
2294	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2295	depends on COMPAT_32
2296	help
2297	  Certain buggy versions of glibc will crash if they are
2298	  presented with a 32-bit vDSO that is not mapped at the address
2299	  indicated in its segment table.
2300
2301	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2302	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2303	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2304	  the only released version with the bug, but OpenSUSE 9
2305	  contains a buggy "glibc 2.3.2".
2306
2307	  The symptom of the bug is that everything crashes on startup, saying:
2308	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2309
2310	  Saying Y here changes the default value of the vdso32 boot
2311	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2312	  This works around the glibc bug but hurts performance.
2313
2314	  If unsure, say N: if you are compiling your own kernel, you
2315	  are unlikely to be using a buggy version of glibc.
2316
2317choice
2318	prompt "vsyscall table for legacy applications"
2319	depends on X86_64
2320	default LEGACY_VSYSCALL_XONLY
2321	help
2322	  Legacy user code that does not know how to find the vDSO expects
2323	  to be able to issue three syscalls by calling fixed addresses in
2324	  kernel space. Since this location is not randomized with ASLR,
2325	  it can be used to assist security vulnerability exploitation.
2326
2327	  This setting can be changed at boot time via the kernel command
2328	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2329	  is deprecated and can only be enabled using the kernel command
2330	  line.
2331
2332	  On a system with recent enough glibc (2.14 or newer) and no
2333	  static binaries, you can say None without a performance penalty
2334	  to improve security.
2335
2336	  If unsure, select "Emulate execution only".
2337
2338	config LEGACY_VSYSCALL_XONLY
2339		bool "Emulate execution only"
2340		help
2341		  The kernel traps and emulates calls into the fixed vsyscall
2342		  address mapping and does not allow reads.  This
2343		  configuration is recommended when userspace might use the
2344		  legacy vsyscall area but support for legacy binary
2345		  instrumentation of legacy code is not needed.  It mitigates
2346		  certain uses of the vsyscall area as an ASLR-bypassing
2347		  buffer.
2348
2349	config LEGACY_VSYSCALL_NONE
2350		bool "None"
2351		help
2352		  There will be no vsyscall mapping at all. This will
2353		  eliminate any risk of ASLR bypass due to the vsyscall
2354		  fixed address mapping. Attempts to use the vsyscalls
2355		  will be reported to dmesg, so that either old or
2356		  malicious userspace programs can be identified.
2357
2358endchoice
2359
2360config CMDLINE_BOOL
2361	bool "Built-in kernel command line"
2362	help
2363	  Allow for specifying boot arguments to the kernel at
2364	  build time.  On some systems (e.g. embedded ones), it is
2365	  necessary or convenient to provide some or all of the
2366	  kernel boot arguments with the kernel itself (that is,
2367	  to not rely on the boot loader to provide them.)
2368
2369	  To compile command line arguments into the kernel,
2370	  set this option to 'Y', then fill in the
2371	  boot arguments in CONFIG_CMDLINE.
2372
2373	  Systems with fully functional boot loaders (i.e. non-embedded)
2374	  should leave this option set to 'N'.
2375
2376config CMDLINE
2377	string "Built-in kernel command string"
2378	depends on CMDLINE_BOOL
2379	default ""
2380	help
2381	  Enter arguments here that should be compiled into the kernel
2382	  image and used at boot time.  If the boot loader provides a
2383	  command line at boot time, it is appended to this string to
2384	  form the full kernel command line, when the system boots.
2385
2386	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2387	  change this behavior.
2388
2389	  In most cases, the command line (whether built-in or provided
2390	  by the boot loader) should specify the device for the root
2391	  file system.
2392
2393config CMDLINE_OVERRIDE
2394	bool "Built-in command line overrides boot loader arguments"
2395	depends on CMDLINE_BOOL && CMDLINE != ""
2396	help
2397	  Set this option to 'Y' to have the kernel ignore the boot loader
2398	  command line, and use ONLY the built-in command line.
2399
2400	  This is used to work around broken boot loaders.  This should
2401	  be set to 'N' under normal conditions.
2402
2403config MODIFY_LDT_SYSCALL
2404	bool "Enable the LDT (local descriptor table)" if EXPERT
2405	default y
2406	help
2407	  Linux can allow user programs to install a per-process x86
2408	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2409	  call.  This is required to run 16-bit or segmented code such as
2410	  DOSEMU or some Wine programs.  It is also used by some very old
2411	  threading libraries.
2412
2413	  Enabling this feature adds a small amount of overhead to
2414	  context switches and increases the low-level kernel attack
2415	  surface.  Disabling it removes the modify_ldt(2) system call.
2416
2417	  Saying 'N' here may make sense for embedded or server kernels.
2418
2419config STRICT_SIGALTSTACK_SIZE
2420	bool "Enforce strict size checking for sigaltstack"
2421	depends on DYNAMIC_SIGFRAME
2422	help
2423	  For historical reasons MINSIGSTKSZ is a constant which became
2424	  already too small with AVX512 support. Add a mechanism to
2425	  enforce strict checking of the sigaltstack size against the
2426	  real size of the FPU frame. This option enables the check
2427	  by default. It can also be controlled via the kernel command
2428	  line option 'strict_sas_size' independent of this config
2429	  switch. Enabling it might break existing applications which
2430	  allocate a too small sigaltstack but 'work' because they
2431	  never get a signal delivered.
2432
2433	  Say 'N' unless you want to really enforce this check.
2434
2435source "kernel/livepatch/Kconfig"
2436
2437endmenu
2438
2439config CC_HAS_SLS
2440	def_bool $(cc-option,-mharden-sls=all)
2441
2442config CC_HAS_RETURN_THUNK
2443	def_bool $(cc-option,-mfunction-return=thunk-extern)
2444
2445menuconfig SPECULATION_MITIGATIONS
2446	bool "Mitigations for speculative execution vulnerabilities"
2447	default y
2448	help
2449	  Say Y here to enable options which enable mitigations for
2450	  speculative execution hardware vulnerabilities.
2451
2452	  If you say N, all mitigations will be disabled. You really
2453	  should know what you are doing to say so.
2454
2455if SPECULATION_MITIGATIONS
2456
2457config PAGE_TABLE_ISOLATION
2458	bool "Remove the kernel mapping in user mode"
2459	default y
2460	depends on (X86_64 || X86_PAE)
2461	help
2462	  This feature reduces the number of hardware side channels by
2463	  ensuring that the majority of kernel addresses are not mapped
2464	  into userspace.
2465
2466	  See Documentation/x86/pti.rst for more details.
2467
2468config RETPOLINE
2469	bool "Avoid speculative indirect branches in kernel"
2470	select OBJTOOL if HAVE_OBJTOOL
2471	default y
2472	help
2473	  Compile kernel with the retpoline compiler options to guard against
2474	  kernel-to-user data leaks by avoiding speculative indirect
2475	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2476	  support for full protection. The kernel may run slower.
2477
2478config RETHUNK
2479	bool "Enable return-thunks"
2480	depends on RETPOLINE && CC_HAS_RETURN_THUNK
2481	select OBJTOOL if HAVE_OBJTOOL
2482	default y if X86_64
2483	help
2484	  Compile the kernel with the return-thunks compiler option to guard
2485	  against kernel-to-user data leaks by avoiding return speculation.
2486	  Requires a compiler with -mfunction-return=thunk-extern
2487	  support for full protection. The kernel may run slower.
2488
2489config CPU_UNRET_ENTRY
2490	bool "Enable UNRET on kernel entry"
2491	depends on CPU_SUP_AMD && RETHUNK && X86_64
2492	default y
2493	help
2494	  Compile the kernel with support for the retbleed=unret mitigation.
2495
2496config CPU_IBPB_ENTRY
2497	bool "Enable IBPB on kernel entry"
2498	depends on CPU_SUP_AMD && X86_64
2499	default y
2500	help
2501	  Compile the kernel with support for the retbleed=ibpb mitigation.
2502
2503config CPU_IBRS_ENTRY
2504	bool "Enable IBRS on kernel entry"
2505	depends on CPU_SUP_INTEL && X86_64
2506	default y
2507	help
2508	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2509	  This mitigates both spectre_v2 and retbleed at great cost to
2510	  performance.
2511
2512config SLS
2513	bool "Mitigate Straight-Line-Speculation"
2514	depends on CC_HAS_SLS && X86_64
2515	select OBJTOOL if HAVE_OBJTOOL
2516	default n
2517	help
2518	  Compile the kernel with straight-line-speculation options to guard
2519	  against straight line speculation. The kernel image might be slightly
2520	  larger.
2521
2522endif
2523
2524config ARCH_HAS_ADD_PAGES
2525	def_bool y
2526	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2527
2528config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2529	def_bool y
2530
2531menu "Power management and ACPI options"
2532
2533config ARCH_HIBERNATION_HEADER
2534	def_bool y
2535	depends on HIBERNATION
2536
2537source "kernel/power/Kconfig"
2538
2539source "drivers/acpi/Kconfig"
2540
2541config X86_APM_BOOT
2542	def_bool y
2543	depends on APM
2544
2545menuconfig APM
2546	tristate "APM (Advanced Power Management) BIOS support"
2547	depends on X86_32 && PM_SLEEP
2548	help
2549	  APM is a BIOS specification for saving power using several different
2550	  techniques. This is mostly useful for battery powered laptops with
2551	  APM compliant BIOSes. If you say Y here, the system time will be
2552	  reset after a RESUME operation, the /proc/apm device will provide
2553	  battery status information, and user-space programs will receive
2554	  notification of APM "events" (e.g. battery status change).
2555
2556	  If you select "Y" here, you can disable actual use of the APM
2557	  BIOS by passing the "apm=off" option to the kernel at boot time.
2558
2559	  Note that the APM support is almost completely disabled for
2560	  machines with more than one CPU.
2561
2562	  In order to use APM, you will need supporting software. For location
2563	  and more information, read <file:Documentation/power/apm-acpi.rst>
2564	  and the Battery Powered Linux mini-HOWTO, available from
2565	  <http://www.tldp.org/docs.html#howto>.
2566
2567	  This driver does not spin down disk drives (see the hdparm(8)
2568	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2569	  VESA-compliant "green" monitors.
2570
2571	  This driver does not support the TI 4000M TravelMate and the ACER
2572	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2573	  desktop machines also don't have compliant BIOSes, and this driver
2574	  may cause those machines to panic during the boot phase.
2575
2576	  Generally, if you don't have a battery in your machine, there isn't
2577	  much point in using this driver and you should say N. If you get
2578	  random kernel OOPSes or reboots that don't seem to be related to
2579	  anything, try disabling/enabling this option (or disabling/enabling
2580	  APM in your BIOS).
2581
2582	  Some other things you should try when experiencing seemingly random,
2583	  "weird" problems:
2584
2585	  1) make sure that you have enough swap space and that it is
2586	  enabled.
2587	  2) pass the "idle=poll" option to the kernel
2588	  3) switch on floating point emulation in the kernel and pass
2589	  the "no387" option to the kernel
2590	  4) pass the "floppy=nodma" option to the kernel
2591	  5) pass the "mem=4M" option to the kernel (thereby disabling
2592	  all but the first 4 MB of RAM)
2593	  6) make sure that the CPU is not over clocked.
2594	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2595	  8) disable the cache from your BIOS settings
2596	  9) install a fan for the video card or exchange video RAM
2597	  10) install a better fan for the CPU
2598	  11) exchange RAM chips
2599	  12) exchange the motherboard.
2600
2601	  To compile this driver as a module, choose M here: the
2602	  module will be called apm.
2603
2604if APM
2605
2606config APM_IGNORE_USER_SUSPEND
2607	bool "Ignore USER SUSPEND"
2608	help
2609	  This option will ignore USER SUSPEND requests. On machines with a
2610	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2611	  series notebooks, it is necessary to say Y because of a BIOS bug.
2612
2613config APM_DO_ENABLE
2614	bool "Enable PM at boot time"
2615	help
2616	  Enable APM features at boot time. From page 36 of the APM BIOS
2617	  specification: "When disabled, the APM BIOS does not automatically
2618	  power manage devices, enter the Standby State, enter the Suspend
2619	  State, or take power saving steps in response to CPU Idle calls."
2620	  This driver will make CPU Idle calls when Linux is idle (unless this
2621	  feature is turned off -- see "Do CPU IDLE calls", below). This
2622	  should always save battery power, but more complicated APM features
2623	  will be dependent on your BIOS implementation. You may need to turn
2624	  this option off if your computer hangs at boot time when using APM
2625	  support, or if it beeps continuously instead of suspending. Turn
2626	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2627	  T400CDT. This is off by default since most machines do fine without
2628	  this feature.
2629
2630config APM_CPU_IDLE
2631	depends on CPU_IDLE
2632	bool "Make CPU Idle calls when idle"
2633	help
2634	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2635	  On some machines, this can activate improved power savings, such as
2636	  a slowed CPU clock rate, when the machine is idle. These idle calls
2637	  are made after the idle loop has run for some length of time (e.g.,
2638	  333 mS). On some machines, this will cause a hang at boot time or
2639	  whenever the CPU becomes idle. (On machines with more than one CPU,
2640	  this option does nothing.)
2641
2642config APM_DISPLAY_BLANK
2643	bool "Enable console blanking using APM"
2644	help
2645	  Enable console blanking using the APM. Some laptops can use this to
2646	  turn off the LCD backlight when the screen blanker of the Linux
2647	  virtual console blanks the screen. Note that this is only used by
2648	  the virtual console screen blanker, and won't turn off the backlight
2649	  when using the X Window system. This also doesn't have anything to
2650	  do with your VESA-compliant power-saving monitor. Further, this
2651	  option doesn't work for all laptops -- it might not turn off your
2652	  backlight at all, or it might print a lot of errors to the console,
2653	  especially if you are using gpm.
2654
2655config APM_ALLOW_INTS
2656	bool "Allow interrupts during APM BIOS calls"
2657	help
2658	  Normally we disable external interrupts while we are making calls to
2659	  the APM BIOS as a measure to lessen the effects of a badly behaving
2660	  BIOS implementation.  The BIOS should reenable interrupts if it
2661	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2662	  many of the newer IBM Thinkpads.  If you experience hangs when you
2663	  suspend, try setting this to Y.  Otherwise, say N.
2664
2665endif # APM
2666
2667source "drivers/cpufreq/Kconfig"
2668
2669source "drivers/cpuidle/Kconfig"
2670
2671source "drivers/idle/Kconfig"
2672
2673endmenu
2674
2675menu "Bus options (PCI etc.)"
2676
2677choice
2678	prompt "PCI access mode"
2679	depends on X86_32 && PCI
2680	default PCI_GOANY
2681	help
2682	  On PCI systems, the BIOS can be used to detect the PCI devices and
2683	  determine their configuration. However, some old PCI motherboards
2684	  have BIOS bugs and may crash if this is done. Also, some embedded
2685	  PCI-based systems don't have any BIOS at all. Linux can also try to
2686	  detect the PCI hardware directly without using the BIOS.
2687
2688	  With this option, you can specify how Linux should detect the
2689	  PCI devices. If you choose "BIOS", the BIOS will be used,
2690	  if you choose "Direct", the BIOS won't be used, and if you
2691	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2692	  If you choose "Any", the kernel will try MMCONFIG, then the
2693	  direct access method and falls back to the BIOS if that doesn't
2694	  work. If unsure, go with the default, which is "Any".
2695
2696config PCI_GOBIOS
2697	bool "BIOS"
2698
2699config PCI_GOMMCONFIG
2700	bool "MMConfig"
2701
2702config PCI_GODIRECT
2703	bool "Direct"
2704
2705config PCI_GOOLPC
2706	bool "OLPC XO-1"
2707	depends on OLPC
2708
2709config PCI_GOANY
2710	bool "Any"
2711
2712endchoice
2713
2714config PCI_BIOS
2715	def_bool y
2716	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2717
2718# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2719config PCI_DIRECT
2720	def_bool y
2721	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2722
2723config PCI_MMCONFIG
2724	bool "Support mmconfig PCI config space access" if X86_64
2725	default y
2726	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2727	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2728
2729config PCI_OLPC
2730	def_bool y
2731	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2732
2733config PCI_XEN
2734	def_bool y
2735	depends on PCI && XEN
2736
2737config MMCONF_FAM10H
2738	def_bool y
2739	depends on X86_64 && PCI_MMCONFIG && ACPI
2740
2741config PCI_CNB20LE_QUIRK
2742	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2743	depends on PCI
2744	help
2745	  Read the PCI windows out of the CNB20LE host bridge. This allows
2746	  PCI hotplug to work on systems with the CNB20LE chipset which do
2747	  not have ACPI.
2748
2749	  There's no public spec for this chipset, and this functionality
2750	  is known to be incomplete.
2751
2752	  You should say N unless you know you need this.
2753
2754config ISA_BUS
2755	bool "ISA bus support on modern systems" if EXPERT
2756	help
2757	  Expose ISA bus device drivers and options available for selection and
2758	  configuration. Enable this option if your target machine has an ISA
2759	  bus. ISA is an older system, displaced by PCI and newer bus
2760	  architectures -- if your target machine is modern, it probably does
2761	  not have an ISA bus.
2762
2763	  If unsure, say N.
2764
2765# x86_64 have no ISA slots, but can have ISA-style DMA.
2766config ISA_DMA_API
2767	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2768	default y
2769	help
2770	  Enables ISA-style DMA support for devices requiring such controllers.
2771	  If unsure, say Y.
2772
2773if X86_32
2774
2775config ISA
2776	bool "ISA support"
2777	help
2778	  Find out whether you have ISA slots on your motherboard.  ISA is the
2779	  name of a bus system, i.e. the way the CPU talks to the other stuff
2780	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2781	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2782	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2783
2784config SCx200
2785	tristate "NatSemi SCx200 support"
2786	help
2787	  This provides basic support for National Semiconductor's
2788	  (now AMD's) Geode processors.  The driver probes for the
2789	  PCI-IDs of several on-chip devices, so its a good dependency
2790	  for other scx200_* drivers.
2791
2792	  If compiled as a module, the driver is named scx200.
2793
2794config SCx200HR_TIMER
2795	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2796	depends on SCx200
2797	default y
2798	help
2799	  This driver provides a clocksource built upon the on-chip
2800	  27MHz high-resolution timer.  Its also a workaround for
2801	  NSC Geode SC-1100's buggy TSC, which loses time when the
2802	  processor goes idle (as is done by the scheduler).  The
2803	  other workaround is idle=poll boot option.
2804
2805config OLPC
2806	bool "One Laptop Per Child support"
2807	depends on !X86_PAE
2808	select GPIOLIB
2809	select OF
2810	select OF_PROMTREE
2811	select IRQ_DOMAIN
2812	select OLPC_EC
2813	help
2814	  Add support for detecting the unique features of the OLPC
2815	  XO hardware.
2816
2817config OLPC_XO1_PM
2818	bool "OLPC XO-1 Power Management"
2819	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2820	help
2821	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2822
2823config OLPC_XO1_RTC
2824	bool "OLPC XO-1 Real Time Clock"
2825	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2826	help
2827	  Add support for the XO-1 real time clock, which can be used as a
2828	  programmable wakeup source.
2829
2830config OLPC_XO1_SCI
2831	bool "OLPC XO-1 SCI extras"
2832	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2833	depends on INPUT=y
2834	select POWER_SUPPLY
2835	help
2836	  Add support for SCI-based features of the OLPC XO-1 laptop:
2837	   - EC-driven system wakeups
2838	   - Power button
2839	   - Ebook switch
2840	   - Lid switch
2841	   - AC adapter status updates
2842	   - Battery status updates
2843
2844config OLPC_XO15_SCI
2845	bool "OLPC XO-1.5 SCI extras"
2846	depends on OLPC && ACPI
2847	select POWER_SUPPLY
2848	help
2849	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2850	   - EC-driven system wakeups
2851	   - AC adapter status updates
2852	   - Battery status updates
2853
2854config ALIX
2855	bool "PCEngines ALIX System Support (LED setup)"
2856	select GPIOLIB
2857	help
2858	  This option enables system support for the PCEngines ALIX.
2859	  At present this just sets up LEDs for GPIO control on
2860	  ALIX2/3/6 boards.  However, other system specific setup should
2861	  get added here.
2862
2863	  Note: You must still enable the drivers for GPIO and LED support
2864	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2865
2866	  Note: You have to set alix.force=1 for boards with Award BIOS.
2867
2868config NET5501
2869	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2870	select GPIOLIB
2871	help
2872	  This option enables system support for the Soekris Engineering net5501.
2873
2874config GEOS
2875	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2876	select GPIOLIB
2877	depends on DMI
2878	help
2879	  This option enables system support for the Traverse Technologies GEOS.
2880
2881config TS5500
2882	bool "Technologic Systems TS-5500 platform support"
2883	depends on MELAN
2884	select CHECK_SIGNATURE
2885	select NEW_LEDS
2886	select LEDS_CLASS
2887	help
2888	  This option enables system support for the Technologic Systems TS-5500.
2889
2890endif # X86_32
2891
2892config AMD_NB
2893	def_bool y
2894	depends on CPU_SUP_AMD && PCI
2895
2896endmenu
2897
2898menu "Binary Emulations"
2899
2900config IA32_EMULATION
2901	bool "IA32 Emulation"
2902	depends on X86_64
2903	select ARCH_WANT_OLD_COMPAT_IPC
2904	select BINFMT_ELF
2905	select COMPAT_OLD_SIGACTION
2906	help
2907	  Include code to run legacy 32-bit programs under a
2908	  64-bit kernel. You should likely turn this on, unless you're
2909	  100% sure that you don't have any 32-bit programs left.
2910
2911config X86_X32_ABI
2912	bool "x32 ABI for 64-bit mode"
2913	depends on X86_64
2914	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2915	# compressed debug sections to x86_x32 properly:
2916	# https://github.com/ClangBuiltLinux/linux/issues/514
2917	# https://github.com/ClangBuiltLinux/linux/issues/1141
2918	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2919	help
2920	  Include code to run binaries for the x32 native 32-bit ABI
2921	  for 64-bit processors.  An x32 process gets access to the
2922	  full 64-bit register file and wide data path while leaving
2923	  pointers at 32 bits for smaller memory footprint.
2924
2925config COMPAT_32
2926	def_bool y
2927	depends on IA32_EMULATION || X86_32
2928	select HAVE_UID16
2929	select OLD_SIGSUSPEND3
2930
2931config COMPAT
2932	def_bool y
2933	depends on IA32_EMULATION || X86_X32_ABI
2934
2935config COMPAT_FOR_U64_ALIGNMENT
2936	def_bool y
2937	depends on COMPAT
2938
2939endmenu
2940
2941config HAVE_ATOMIC_IOMAP
2942	def_bool y
2943	depends on X86_32
2944
2945source "arch/x86/kvm/Kconfig"
2946
2947source "arch/x86/Kconfig.assembler"
2948