xref: /openbmc/linux/arch/x86/Kconfig (revision ce732a75)
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_LTO_CLANG
112	select ARCH_SUPPORTS_LTO_CLANG_THIN
113	select ARCH_USE_BUILTIN_BSWAP
114	select ARCH_USE_MEMTEST
115	select ARCH_USE_QUEUED_RWLOCKS
116	select ARCH_USE_QUEUED_SPINLOCKS
117	select ARCH_USE_SYM_ANNOTATIONS
118	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
119	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
120	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
121	select ARCH_WANTS_NO_INSTR
122	select ARCH_WANT_GENERAL_HUGETLB
123	select ARCH_WANT_HUGE_PMD_SHARE
124	select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP	if X86_64
125	select ARCH_WANT_LD_ORPHAN_WARN
126	select ARCH_WANTS_THP_SWAP		if X86_64
127	select ARCH_HAS_PARANOID_L1D_FLUSH
128	select BUILDTIME_TABLE_SORT
129	select CLKEVT_I8253
130	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
131	select CLOCKSOURCE_WATCHDOG
132	# Word-size accesses may read uninitialized data past the trailing \0
133	# in strings and cause false KMSAN reports.
134	select DCACHE_WORD_ACCESS		if !KMSAN
135	select DYNAMIC_SIGFRAME
136	select EDAC_ATOMIC_SCRUB
137	select EDAC_SUPPORT
138	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
139	select GENERIC_CLOCKEVENTS_MIN_ADJUST
140	select GENERIC_CMOS_UPDATE
141	select GENERIC_CPU_AUTOPROBE
142	select GENERIC_CPU_VULNERABILITIES
143	select GENERIC_EARLY_IOREMAP
144	select GENERIC_ENTRY
145	select GENERIC_IOMAP
146	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
147	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
148	select GENERIC_IRQ_MIGRATION		if SMP
149	select GENERIC_IRQ_PROBE
150	select GENERIC_IRQ_RESERVATION_MODE
151	select GENERIC_IRQ_SHOW
152	select GENERIC_PENDING_IRQ		if SMP
153	select GENERIC_PTDUMP
154	select GENERIC_SMP_IDLE_THREAD
155	select GENERIC_TIME_VSYSCALL
156	select GENERIC_GETTIMEOFDAY
157	select GENERIC_VDSO_TIME_NS
158	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
159	select HARDIRQS_SW_RESEND
160	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
161	select HAVE_ACPI_APEI			if ACPI
162	select HAVE_ACPI_APEI_NMI		if ACPI
163	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
164	select HAVE_ARCH_AUDITSYSCALL
165	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
166	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
167	select HAVE_ARCH_JUMP_LABEL
168	select HAVE_ARCH_JUMP_LABEL_RELATIVE
169	select HAVE_ARCH_KASAN			if X86_64
170	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
171	select HAVE_ARCH_KFENCE
172	select HAVE_ARCH_KMSAN			if X86_64
173	select HAVE_ARCH_KGDB
174	select HAVE_ARCH_MMAP_RND_BITS		if MMU
175	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
176	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
177	select HAVE_ARCH_PREL32_RELOCATIONS
178	select HAVE_ARCH_SECCOMP_FILTER
179	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
180	select HAVE_ARCH_STACKLEAK
181	select HAVE_ARCH_TRACEHOOK
182	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
183	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
184	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
185	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
186	select HAVE_ARCH_VMAP_STACK		if X86_64
187	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
188	select HAVE_ARCH_WITHIN_STACK_FRAMES
189	select HAVE_ASM_MODVERSIONS
190	select HAVE_CMPXCHG_DOUBLE
191	select HAVE_CMPXCHG_LOCAL
192	select HAVE_CONTEXT_TRACKING_USER		if X86_64
193	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
194	select HAVE_C_RECORDMCOUNT
195	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
196	select HAVE_BUILDTIME_MCOUNT_SORT
197	select HAVE_DEBUG_KMEMLEAK
198	select HAVE_DMA_CONTIGUOUS
199	select HAVE_DYNAMIC_FTRACE
200	select HAVE_DYNAMIC_FTRACE_WITH_REGS
201	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
202	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
203	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
204	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
205	select HAVE_EBPF_JIT
206	select HAVE_EFFICIENT_UNALIGNED_ACCESS
207	select HAVE_EISA
208	select HAVE_EXIT_THREAD
209	select HAVE_FAST_GUP
210	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
211	select HAVE_FTRACE_MCOUNT_RECORD
212	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
213	select HAVE_FUNCTION_TRACER
214	select HAVE_GCC_PLUGINS
215	select HAVE_HW_BREAKPOINT
216	select HAVE_IOREMAP_PROT
217	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
218	select HAVE_IRQ_TIME_ACCOUNTING
219	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
220	select HAVE_KERNEL_BZIP2
221	select HAVE_KERNEL_GZIP
222	select HAVE_KERNEL_LZ4
223	select HAVE_KERNEL_LZMA
224	select HAVE_KERNEL_LZO
225	select HAVE_KERNEL_XZ
226	select HAVE_KERNEL_ZSTD
227	select HAVE_KPROBES
228	select HAVE_KPROBES_ON_FTRACE
229	select HAVE_FUNCTION_ERROR_INJECTION
230	select HAVE_KRETPROBES
231	select HAVE_RETHOOK
232	select HAVE_KVM
233	select HAVE_LIVEPATCH			if X86_64
234	select HAVE_MIXED_BREAKPOINTS_REGS
235	select HAVE_MOD_ARCH_SPECIFIC
236	select HAVE_MOVE_PMD
237	select HAVE_MOVE_PUD
238	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
239	select HAVE_NMI
240	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
241	select HAVE_OBJTOOL			if X86_64
242	select HAVE_OPTPROBES
243	select HAVE_PCSPKR_PLATFORM
244	select HAVE_PERF_EVENTS
245	select HAVE_PERF_EVENTS_NMI
246	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
247	select HAVE_PCI
248	select HAVE_PERF_REGS
249	select HAVE_PERF_USER_STACK_DUMP
250	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
251	select MMU_GATHER_MERGE_VMAS
252	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
253	select HAVE_REGS_AND_STACK_ACCESS_API
254	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
255	select HAVE_FUNCTION_ARG_ACCESS_API
256	select HAVE_SETUP_PER_CPU_AREA
257	select HAVE_SOFTIRQ_ON_OWN_STACK
258	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
259	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
260	select HAVE_STATIC_CALL
261	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
262	select HAVE_PREEMPT_DYNAMIC_CALL
263	select HAVE_RSEQ
264	select HAVE_SYSCALL_TRACEPOINTS
265	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
266	select HAVE_UNSTABLE_SCHED_CLOCK
267	select HAVE_USER_RETURN_NOTIFIER
268	select HAVE_GENERIC_VDSO
269	select HOTPLUG_SMT			if SMP
270	select IRQ_FORCED_THREADING
271	select NEED_PER_CPU_EMBED_FIRST_CHUNK
272	select NEED_PER_CPU_PAGE_FIRST_CHUNK
273	select NEED_SG_DMA_LENGTH
274	select PCI_DOMAINS			if PCI
275	select PCI_LOCKLESS_CONFIG		if PCI
276	select PERF_EVENTS
277	select RTC_LIB
278	select RTC_MC146818_LIB
279	select SPARSE_IRQ
280	select SRCU
281	select SYSCTL_EXCEPTION_TRACE
282	select THREAD_INFO_IN_TASK
283	select TRACE_IRQFLAGS_SUPPORT
284	select TRACE_IRQFLAGS_NMI_SUPPORT
285	select USER_STACKTRACE_SUPPORT
286	select HAVE_ARCH_KCSAN			if X86_64
287	select X86_FEATURE_NAMES		if PROC_FS
288	select PROC_PID_ARCH_STATUS		if PROC_FS
289	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
290	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
291
292config INSTRUCTION_DECODER
293	def_bool y
294	depends on KPROBES || PERF_EVENTS || UPROBES
295
296config OUTPUT_FORMAT
297	string
298	default "elf32-i386" if X86_32
299	default "elf64-x86-64" if X86_64
300
301config LOCKDEP_SUPPORT
302	def_bool y
303
304config STACKTRACE_SUPPORT
305	def_bool y
306
307config MMU
308	def_bool y
309
310config ARCH_MMAP_RND_BITS_MIN
311	default 28 if 64BIT
312	default 8
313
314config ARCH_MMAP_RND_BITS_MAX
315	default 32 if 64BIT
316	default 16
317
318config ARCH_MMAP_RND_COMPAT_BITS_MIN
319	default 8
320
321config ARCH_MMAP_RND_COMPAT_BITS_MAX
322	default 16
323
324config SBUS
325	bool
326
327config GENERIC_ISA_DMA
328	def_bool y
329	depends on ISA_DMA_API
330
331config GENERIC_CSUM
332	bool
333	default y if KMSAN || KASAN
334
335config GENERIC_BUG
336	def_bool y
337	depends on BUG
338	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
339
340config GENERIC_BUG_RELATIVE_POINTERS
341	bool
342
343config ARCH_MAY_HAVE_PC_FDC
344	def_bool y
345	depends on ISA_DMA_API
346
347config GENERIC_CALIBRATE_DELAY
348	def_bool y
349
350config ARCH_HAS_CPU_RELAX
351	def_bool y
352
353config ARCH_HIBERNATION_POSSIBLE
354	def_bool y
355
356config ARCH_NR_GPIO
357	int
358	default 1024 if X86_64
359	default 512
360
361config ARCH_SUSPEND_POSSIBLE
362	def_bool y
363
364config AUDIT_ARCH
365	def_bool y if X86_64
366
367config KASAN_SHADOW_OFFSET
368	hex
369	depends on KASAN
370	default 0xdffffc0000000000
371
372config HAVE_INTEL_TXT
373	def_bool y
374	depends on INTEL_IOMMU && ACPI
375
376config X86_32_SMP
377	def_bool y
378	depends on X86_32 && SMP
379
380config X86_64_SMP
381	def_bool y
382	depends on X86_64 && SMP
383
384config ARCH_SUPPORTS_UPROBES
385	def_bool y
386
387config FIX_EARLYCON_MEM
388	def_bool y
389
390config DYNAMIC_PHYSICAL_MASK
391	bool
392
393config PGTABLE_LEVELS
394	int
395	default 5 if X86_5LEVEL
396	default 4 if X86_64
397	default 3 if X86_PAE
398	default 2
399
400config CC_HAS_SANE_STACKPROTECTOR
401	bool
402	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
403	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
404	help
405	  We have to make sure stack protector is unconditionally disabled if
406	  the compiler produces broken code or if it does not let us control
407	  the segment on 32-bit kernels.
408
409menu "Processor type and features"
410
411config SMP
412	bool "Symmetric multi-processing support"
413	help
414	  This enables support for systems with more than one CPU. If you have
415	  a system with only one CPU, say N. If you have a system with more
416	  than one CPU, say Y.
417
418	  If you say N here, the kernel will run on uni- and multiprocessor
419	  machines, but will use only one CPU of a multiprocessor machine. If
420	  you say Y here, the kernel will run on many, but not all,
421	  uniprocessor machines. On a uniprocessor machine, the kernel
422	  will run faster if you say N here.
423
424	  Note that if you say Y here and choose architecture "586" or
425	  "Pentium" under "Processor family", the kernel will not work on 486
426	  architectures. Similarly, multiprocessor kernels for the "PPro"
427	  architecture may not work on all Pentium based boards.
428
429	  People using multiprocessor machines who say Y here should also say
430	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
431	  Management" code will be disabled if you say Y here.
432
433	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
434	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
435	  <http://www.tldp.org/docs.html#howto>.
436
437	  If you don't know what to do here, say N.
438
439config X86_FEATURE_NAMES
440	bool "Processor feature human-readable names" if EMBEDDED
441	default y
442	help
443	  This option compiles in a table of x86 feature bits and corresponding
444	  names.  This is required to support /proc/cpuinfo and a few kernel
445	  messages.  You can disable this to save space, at the expense of
446	  making those few kernel messages show numeric feature bits instead.
447
448	  If in doubt, say Y.
449
450config X86_X2APIC
451	bool "Support x2apic"
452	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
453	help
454	  This enables x2apic support on CPUs that have this feature.
455
456	  This allows 32-bit apic IDs (so it can support very large systems),
457	  and accesses the local apic via MSRs not via mmio.
458
459	  If you don't know what to do here, say N.
460
461config X86_MPPARSE
462	bool "Enable MPS table" if ACPI
463	default y
464	depends on X86_LOCAL_APIC
465	help
466	  For old smp systems that do not have proper acpi support. Newer systems
467	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
468
469config GOLDFISH
470	def_bool y
471	depends on X86_GOLDFISH
472
473config X86_CPU_RESCTRL
474	bool "x86 CPU resource control support"
475	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
476	select KERNFS
477	select PROC_CPU_RESCTRL		if PROC_FS
478	help
479	  Enable x86 CPU resource control support.
480
481	  Provide support for the allocation and monitoring of system resources
482	  usage by the CPU.
483
484	  Intel calls this Intel Resource Director Technology
485	  (Intel(R) RDT). More information about RDT can be found in the
486	  Intel x86 Architecture Software Developer Manual.
487
488	  AMD calls this AMD Platform Quality of Service (AMD QoS).
489	  More information about AMD QoS can be found in the AMD64 Technology
490	  Platform Quality of Service Extensions manual.
491
492	  Say N if unsure.
493
494if X86_32
495config X86_BIGSMP
496	bool "Support for big SMP systems with more than 8 CPUs"
497	depends on SMP
498	help
499	  This option is needed for the systems that have more than 8 CPUs.
500
501config X86_EXTENDED_PLATFORM
502	bool "Support for extended (non-PC) x86 platforms"
503	default y
504	help
505	  If you disable this option then the kernel will only support
506	  standard PC platforms. (which covers the vast majority of
507	  systems out there.)
508
509	  If you enable this option then you'll be able to select support
510	  for the following (non-PC) 32 bit x86 platforms:
511		Goldfish (Android emulator)
512		AMD Elan
513		RDC R-321x SoC
514		SGI 320/540 (Visual Workstation)
515		STA2X11-based (e.g. Northville)
516		Moorestown MID devices
517
518	  If you have one of these systems, or if you want to build a
519	  generic distribution kernel, say Y here - otherwise say N.
520endif # X86_32
521
522if X86_64
523config X86_EXTENDED_PLATFORM
524	bool "Support for extended (non-PC) x86 platforms"
525	default y
526	help
527	  If you disable this option then the kernel will only support
528	  standard PC platforms. (which covers the vast majority of
529	  systems out there.)
530
531	  If you enable this option then you'll be able to select support
532	  for the following (non-PC) 64 bit x86 platforms:
533		Numascale NumaChip
534		ScaleMP vSMP
535		SGI Ultraviolet
536
537	  If you have one of these systems, or if you want to build a
538	  generic distribution kernel, say Y here - otherwise say N.
539endif # X86_64
540# This is an alphabetically sorted list of 64 bit extended platforms
541# Please maintain the alphabetic order if and when there are additions
542config X86_NUMACHIP
543	bool "Numascale NumaChip"
544	depends on X86_64
545	depends on X86_EXTENDED_PLATFORM
546	depends on NUMA
547	depends on SMP
548	depends on X86_X2APIC
549	depends on PCI_MMCONFIG
550	help
551	  Adds support for Numascale NumaChip large-SMP systems. Needed to
552	  enable more than ~168 cores.
553	  If you don't have one of these, you should say N here.
554
555config X86_VSMP
556	bool "ScaleMP vSMP"
557	select HYPERVISOR_GUEST
558	select PARAVIRT
559	depends on X86_64 && PCI
560	depends on X86_EXTENDED_PLATFORM
561	depends on SMP
562	help
563	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
564	  supposed to run on these EM64T-based machines.  Only choose this option
565	  if you have one of these machines.
566
567config X86_UV
568	bool "SGI Ultraviolet"
569	depends on X86_64
570	depends on X86_EXTENDED_PLATFORM
571	depends on NUMA
572	depends on EFI
573	depends on KEXEC_CORE
574	depends on X86_X2APIC
575	depends on PCI
576	help
577	  This option is needed in order to support SGI Ultraviolet systems.
578	  If you don't have one of these, you should say N here.
579
580# Following is an alphabetically sorted list of 32 bit extended platforms
581# Please maintain the alphabetic order if and when there are additions
582
583config X86_GOLDFISH
584	bool "Goldfish (Virtual Platform)"
585	depends on X86_EXTENDED_PLATFORM
586	help
587	  Enable support for the Goldfish virtual platform used primarily
588	  for Android development. Unless you are building for the Android
589	  Goldfish emulator say N here.
590
591config X86_INTEL_CE
592	bool "CE4100 TV platform"
593	depends on PCI
594	depends on PCI_GODIRECT
595	depends on X86_IO_APIC
596	depends on X86_32
597	depends on X86_EXTENDED_PLATFORM
598	select X86_REBOOTFIXUPS
599	select OF
600	select OF_EARLY_FLATTREE
601	help
602	  Select for the Intel CE media processor (CE4100) SOC.
603	  This option compiles in support for the CE4100 SOC for settop
604	  boxes and media devices.
605
606config X86_INTEL_MID
607	bool "Intel MID platform support"
608	depends on X86_EXTENDED_PLATFORM
609	depends on X86_PLATFORM_DEVICES
610	depends on PCI
611	depends on X86_64 || (PCI_GOANY && X86_32)
612	depends on X86_IO_APIC
613	select I2C
614	select DW_APB_TIMER
615	select INTEL_SCU_PCI
616	help
617	  Select to build a kernel capable of supporting Intel MID (Mobile
618	  Internet Device) platform systems which do not have the PCI legacy
619	  interfaces. If you are building for a PC class system say N here.
620
621	  Intel MID platforms are based on an Intel processor and chipset which
622	  consume less power than most of the x86 derivatives.
623
624config X86_INTEL_QUARK
625	bool "Intel Quark platform support"
626	depends on X86_32
627	depends on X86_EXTENDED_PLATFORM
628	depends on X86_PLATFORM_DEVICES
629	depends on X86_TSC
630	depends on PCI
631	depends on PCI_GOANY
632	depends on X86_IO_APIC
633	select IOSF_MBI
634	select INTEL_IMR
635	select COMMON_CLK
636	help
637	  Select to include support for Quark X1000 SoC.
638	  Say Y here if you have a Quark based system such as the Arduino
639	  compatible Intel Galileo.
640
641config X86_INTEL_LPSS
642	bool "Intel Low Power Subsystem Support"
643	depends on X86 && ACPI && PCI
644	select COMMON_CLK
645	select PINCTRL
646	select IOSF_MBI
647	help
648	  Select to build support for Intel Low Power Subsystem such as
649	  found on Intel Lynxpoint PCH. Selecting this option enables
650	  things like clock tree (common clock framework) and pincontrol
651	  which are needed by the LPSS peripheral drivers.
652
653config X86_AMD_PLATFORM_DEVICE
654	bool "AMD ACPI2Platform devices support"
655	depends on ACPI
656	select COMMON_CLK
657	select PINCTRL
658	help
659	  Select to interpret AMD specific ACPI device to platform device
660	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
661	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
662	  implemented under PINCTRL subsystem.
663
664config IOSF_MBI
665	tristate "Intel SoC IOSF Sideband support for SoC platforms"
666	depends on PCI
667	help
668	  This option enables sideband register access support for Intel SoC
669	  platforms. On these platforms the IOSF sideband is used in lieu of
670	  MSR's for some register accesses, mostly but not limited to thermal
671	  and power. Drivers may query the availability of this device to
672	  determine if they need the sideband in order to work on these
673	  platforms. The sideband is available on the following SoC products.
674	  This list is not meant to be exclusive.
675	   - BayTrail
676	   - Braswell
677	   - Quark
678
679	  You should say Y if you are running a kernel on one of these SoC's.
680
681config IOSF_MBI_DEBUG
682	bool "Enable IOSF sideband access through debugfs"
683	depends on IOSF_MBI && DEBUG_FS
684	help
685	  Select this option to expose the IOSF sideband access registers (MCR,
686	  MDR, MCRX) through debugfs to write and read register information from
687	  different units on the SoC. This is most useful for obtaining device
688	  state information for debug and analysis. As this is a general access
689	  mechanism, users of this option would have specific knowledge of the
690	  device they want to access.
691
692	  If you don't require the option or are in doubt, say N.
693
694config X86_RDC321X
695	bool "RDC R-321x SoC"
696	depends on X86_32
697	depends on X86_EXTENDED_PLATFORM
698	select M486
699	select X86_REBOOTFIXUPS
700	help
701	  This option is needed for RDC R-321x system-on-chip, also known
702	  as R-8610-(G).
703	  If you don't have one of these chips, you should say N here.
704
705config X86_32_NON_STANDARD
706	bool "Support non-standard 32-bit SMP architectures"
707	depends on X86_32 && SMP
708	depends on X86_EXTENDED_PLATFORM
709	help
710	  This option compiles in the bigsmp and STA2X11 default
711	  subarchitectures.  It is intended for a generic binary
712	  kernel. If you select them all, kernel will probe it one by
713	  one and will fallback to default.
714
715# Alphabetically sorted list of Non standard 32 bit platforms
716
717config X86_SUPPORTS_MEMORY_FAILURE
718	def_bool y
719	# MCE code calls memory_failure():
720	depends on X86_MCE
721	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
722	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
723	depends on X86_64 || !SPARSEMEM
724	select ARCH_SUPPORTS_MEMORY_FAILURE
725
726config STA2X11
727	bool "STA2X11 Companion Chip Support"
728	depends on X86_32_NON_STANDARD && PCI
729	select SWIOTLB
730	select MFD_STA2X11
731	select GPIOLIB
732	help
733	  This adds support for boards based on the STA2X11 IO-Hub,
734	  a.k.a. "ConneXt". The chip is used in place of the standard
735	  PC chipset, so all "standard" peripherals are missing. If this
736	  option is selected the kernel will still be able to boot on
737	  standard PC machines.
738
739config X86_32_IRIS
740	tristate "Eurobraille/Iris poweroff module"
741	depends on X86_32
742	help
743	  The Iris machines from EuroBraille do not have APM or ACPI support
744	  to shut themselves down properly.  A special I/O sequence is
745	  needed to do so, which is what this module does at
746	  kernel shutdown.
747
748	  This is only for Iris machines from EuroBraille.
749
750	  If unused, say N.
751
752config SCHED_OMIT_FRAME_POINTER
753	def_bool y
754	prompt "Single-depth WCHAN output"
755	depends on X86
756	help
757	  Calculate simpler /proc/<PID>/wchan values. If this option
758	  is disabled then wchan values will recurse back to the
759	  caller function. This provides more accurate wchan values,
760	  at the expense of slightly more scheduling overhead.
761
762	  If in doubt, say "Y".
763
764menuconfig HYPERVISOR_GUEST
765	bool "Linux guest support"
766	help
767	  Say Y here to enable options for running Linux under various hyper-
768	  visors. This option enables basic hypervisor detection and platform
769	  setup.
770
771	  If you say N, all options in this submenu will be skipped and
772	  disabled, and Linux guest support won't be built in.
773
774if HYPERVISOR_GUEST
775
776config PARAVIRT
777	bool "Enable paravirtualization code"
778	depends on HAVE_STATIC_CALL
779	help
780	  This changes the kernel so it can modify itself when it is run
781	  under a hypervisor, potentially improving performance significantly
782	  over full virtualization.  However, when run without a hypervisor
783	  the kernel is theoretically slower and slightly larger.
784
785config PARAVIRT_XXL
786	bool
787
788config PARAVIRT_DEBUG
789	bool "paravirt-ops debugging"
790	depends on PARAVIRT && DEBUG_KERNEL
791	help
792	  Enable to debug paravirt_ops internals.  Specifically, BUG if
793	  a paravirt_op is missing when it is called.
794
795config PARAVIRT_SPINLOCKS
796	bool "Paravirtualization layer for spinlocks"
797	depends on PARAVIRT && SMP
798	help
799	  Paravirtualized spinlocks allow a pvops backend to replace the
800	  spinlock implementation with something virtualization-friendly
801	  (for example, block the virtual CPU rather than spinning).
802
803	  It has a minimal impact on native kernels and gives a nice performance
804	  benefit on paravirtualized KVM / Xen kernels.
805
806	  If you are unsure how to answer this question, answer Y.
807
808config X86_HV_CALLBACK_VECTOR
809	def_bool n
810
811source "arch/x86/xen/Kconfig"
812
813config KVM_GUEST
814	bool "KVM Guest support (including kvmclock)"
815	depends on PARAVIRT
816	select PARAVIRT_CLOCK
817	select ARCH_CPUIDLE_HALTPOLL
818	select X86_HV_CALLBACK_VECTOR
819	default y
820	help
821	  This option enables various optimizations for running under the KVM
822	  hypervisor. It includes a paravirtualized clock, so that instead
823	  of relying on a PIT (or probably other) emulation by the
824	  underlying device model, the host provides the guest with
825	  timing infrastructure such as time of day, and system time
826
827config ARCH_CPUIDLE_HALTPOLL
828	def_bool n
829	prompt "Disable host haltpoll when loading haltpoll driver"
830	help
831	  If virtualized under KVM, disable host haltpoll.
832
833config PVH
834	bool "Support for running PVH guests"
835	help
836	  This option enables the PVH entry point for guest virtual machines
837	  as specified in the x86/HVM direct boot ABI.
838
839config PARAVIRT_TIME_ACCOUNTING
840	bool "Paravirtual steal time accounting"
841	depends on PARAVIRT
842	help
843	  Select this option to enable fine granularity task steal time
844	  accounting. Time spent executing other tasks in parallel with
845	  the current vCPU is discounted from the vCPU power. To account for
846	  that, there can be a small performance impact.
847
848	  If in doubt, say N here.
849
850config PARAVIRT_CLOCK
851	bool
852
853config JAILHOUSE_GUEST
854	bool "Jailhouse non-root cell support"
855	depends on X86_64 && PCI
856	select X86_PM_TIMER
857	help
858	  This option allows to run Linux as guest in a Jailhouse non-root
859	  cell. You can leave this option disabled if you only want to start
860	  Jailhouse and run Linux afterwards in the root cell.
861
862config ACRN_GUEST
863	bool "ACRN Guest support"
864	depends on X86_64
865	select X86_HV_CALLBACK_VECTOR
866	help
867	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
868	  a flexible, lightweight reference open-source hypervisor, built with
869	  real-time and safety-criticality in mind. It is built for embedded
870	  IOT with small footprint and real-time features. More details can be
871	  found in https://projectacrn.org/.
872
873config INTEL_TDX_GUEST
874	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
875	depends on X86_64 && CPU_SUP_INTEL
876	depends on X86_X2APIC
877	select ARCH_HAS_CC_PLATFORM
878	select X86_MEM_ENCRYPT
879	select X86_MCE
880	help
881	  Support running as a guest under Intel TDX.  Without this support,
882	  the guest kernel can not boot or run under TDX.
883	  TDX includes memory encryption and integrity capabilities
884	  which protect the confidentiality and integrity of guest
885	  memory contents and CPU state. TDX guests are protected from
886	  some attacks from the VMM.
887
888endif # HYPERVISOR_GUEST
889
890source "arch/x86/Kconfig.cpu"
891
892config HPET_TIMER
893	def_bool X86_64
894	prompt "HPET Timer Support" if X86_32
895	help
896	  Use the IA-PC HPET (High Precision Event Timer) to manage
897	  time in preference to the PIT and RTC, if a HPET is
898	  present.
899	  HPET is the next generation timer replacing legacy 8254s.
900	  The HPET provides a stable time base on SMP
901	  systems, unlike the TSC, but it is more expensive to access,
902	  as it is off-chip.  The interface used is documented
903	  in the HPET spec, revision 1.
904
905	  You can safely choose Y here.  However, HPET will only be
906	  activated if the platform and the BIOS support this feature.
907	  Otherwise the 8254 will be used for timing services.
908
909	  Choose N to continue using the legacy 8254 timer.
910
911config HPET_EMULATE_RTC
912	def_bool y
913	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
914
915# Mark as expert because too many people got it wrong.
916# The code disables itself when not needed.
917config DMI
918	default y
919	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
920	bool "Enable DMI scanning" if EXPERT
921	help
922	  Enabled scanning of DMI to identify machine quirks. Say Y
923	  here unless you have verified that your setup is not
924	  affected by entries in the DMI blacklist. Required by PNP
925	  BIOS code.
926
927config GART_IOMMU
928	bool "Old AMD GART IOMMU support"
929	select DMA_OPS
930	select IOMMU_HELPER
931	select SWIOTLB
932	depends on X86_64 && PCI && AMD_NB
933	help
934	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
935	  GART based hardware IOMMUs.
936
937	  The GART supports full DMA access for devices with 32-bit access
938	  limitations, on systems with more than 3 GB. This is usually needed
939	  for USB, sound, many IDE/SATA chipsets and some other devices.
940
941	  Newer systems typically have a modern AMD IOMMU, supported via
942	  the CONFIG_AMD_IOMMU=y config option.
943
944	  In normal configurations this driver is only active when needed:
945	  there's more than 3 GB of memory and the system contains a
946	  32-bit limited device.
947
948	  If unsure, say Y.
949
950config BOOT_VESA_SUPPORT
951	bool
952	help
953	  If true, at least one selected framebuffer driver can take advantage
954	  of VESA video modes set at an early boot stage via the vga= parameter.
955
956config MAXSMP
957	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
958	depends on X86_64 && SMP && DEBUG_KERNEL
959	select CPUMASK_OFFSTACK
960	help
961	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
962	  If unsure, say N.
963
964#
965# The maximum number of CPUs supported:
966#
967# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
968# and which can be configured interactively in the
969# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
970#
971# The ranges are different on 32-bit and 64-bit kernels, depending on
972# hardware capabilities and scalability features of the kernel.
973#
974# ( If MAXSMP is enabled we just use the highest possible value and disable
975#   interactive configuration. )
976#
977
978config NR_CPUS_RANGE_BEGIN
979	int
980	default NR_CPUS_RANGE_END if MAXSMP
981	default    1 if !SMP
982	default    2
983
984config NR_CPUS_RANGE_END
985	int
986	depends on X86_32
987	default   64 if  SMP &&  X86_BIGSMP
988	default    8 if  SMP && !X86_BIGSMP
989	default    1 if !SMP
990
991config NR_CPUS_RANGE_END
992	int
993	depends on X86_64
994	default 8192 if  SMP && CPUMASK_OFFSTACK
995	default  512 if  SMP && !CPUMASK_OFFSTACK
996	default    1 if !SMP
997
998config NR_CPUS_DEFAULT
999	int
1000	depends on X86_32
1001	default   32 if  X86_BIGSMP
1002	default    8 if  SMP
1003	default    1 if !SMP
1004
1005config NR_CPUS_DEFAULT
1006	int
1007	depends on X86_64
1008	default 8192 if  MAXSMP
1009	default   64 if  SMP
1010	default    1 if !SMP
1011
1012config NR_CPUS
1013	int "Maximum number of CPUs" if SMP && !MAXSMP
1014	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1015	default NR_CPUS_DEFAULT
1016	help
1017	  This allows you to specify the maximum number of CPUs which this
1018	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1019	  supported value is 8192, otherwise the maximum value is 512.  The
1020	  minimum value which makes sense is 2.
1021
1022	  This is purely to save memory: each supported CPU adds about 8KB
1023	  to the kernel image.
1024
1025config SCHED_CLUSTER
1026	bool "Cluster scheduler support"
1027	depends on SMP
1028	default y
1029	help
1030	  Cluster scheduler support improves the CPU scheduler's decision
1031	  making when dealing with machines that have clusters of CPUs.
1032	  Cluster usually means a couple of CPUs which are placed closely
1033	  by sharing mid-level caches, last-level cache tags or internal
1034	  busses.
1035
1036config SCHED_SMT
1037	def_bool y if SMP
1038
1039config SCHED_MC
1040	def_bool y
1041	prompt "Multi-core scheduler support"
1042	depends on SMP
1043	help
1044	  Multi-core scheduler support improves the CPU scheduler's decision
1045	  making when dealing with multi-core CPU chips at a cost of slightly
1046	  increased overhead in some places. If unsure say N here.
1047
1048config SCHED_MC_PRIO
1049	bool "CPU core priorities scheduler support"
1050	depends on SCHED_MC && CPU_SUP_INTEL
1051	select X86_INTEL_PSTATE
1052	select CPU_FREQ
1053	default y
1054	help
1055	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1056	  core ordering determined at manufacturing time, which allows
1057	  certain cores to reach higher turbo frequencies (when running
1058	  single threaded workloads) than others.
1059
1060	  Enabling this kernel feature teaches the scheduler about
1061	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1062	  scheduler's CPU selection logic accordingly, so that higher
1063	  overall system performance can be achieved.
1064
1065	  This feature will have no effect on CPUs without this feature.
1066
1067	  If unsure say Y here.
1068
1069config UP_LATE_INIT
1070	def_bool y
1071	depends on !SMP && X86_LOCAL_APIC
1072
1073config X86_UP_APIC
1074	bool "Local APIC support on uniprocessors" if !PCI_MSI
1075	default PCI_MSI
1076	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1077	help
1078	  A local APIC (Advanced Programmable Interrupt Controller) is an
1079	  integrated interrupt controller in the CPU. If you have a single-CPU
1080	  system which has a processor with a local APIC, you can say Y here to
1081	  enable and use it. If you say Y here even though your machine doesn't
1082	  have a local APIC, then the kernel will still run with no slowdown at
1083	  all. The local APIC supports CPU-generated self-interrupts (timer,
1084	  performance counters), and the NMI watchdog which detects hard
1085	  lockups.
1086
1087config X86_UP_IOAPIC
1088	bool "IO-APIC support on uniprocessors"
1089	depends on X86_UP_APIC
1090	help
1091	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1092	  SMP-capable replacement for PC-style interrupt controllers. Most
1093	  SMP systems and many recent uniprocessor systems have one.
1094
1095	  If you have a single-CPU system with an IO-APIC, you can say Y here
1096	  to use it. If you say Y here even though your machine doesn't have
1097	  an IO-APIC, then the kernel will still run with no slowdown at all.
1098
1099config X86_LOCAL_APIC
1100	def_bool y
1101	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1102	select IRQ_DOMAIN_HIERARCHY
1103	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1104
1105config X86_IO_APIC
1106	def_bool y
1107	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1108
1109config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1110	bool "Reroute for broken boot IRQs"
1111	depends on X86_IO_APIC
1112	help
1113	  This option enables a workaround that fixes a source of
1114	  spurious interrupts. This is recommended when threaded
1115	  interrupt handling is used on systems where the generation of
1116	  superfluous "boot interrupts" cannot be disabled.
1117
1118	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1119	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1120	  kernel does during interrupt handling). On chipsets where this
1121	  boot IRQ generation cannot be disabled, this workaround keeps
1122	  the original IRQ line masked so that only the equivalent "boot
1123	  IRQ" is delivered to the CPUs. The workaround also tells the
1124	  kernel to set up the IRQ handler on the boot IRQ line. In this
1125	  way only one interrupt is delivered to the kernel. Otherwise
1126	  the spurious second interrupt may cause the kernel to bring
1127	  down (vital) interrupt lines.
1128
1129	  Only affects "broken" chipsets. Interrupt sharing may be
1130	  increased on these systems.
1131
1132config X86_MCE
1133	bool "Machine Check / overheating reporting"
1134	select GENERIC_ALLOCATOR
1135	default y
1136	help
1137	  Machine Check support allows the processor to notify the
1138	  kernel if it detects a problem (e.g. overheating, data corruption).
1139	  The action the kernel takes depends on the severity of the problem,
1140	  ranging from warning messages to halting the machine.
1141
1142config X86_MCELOG_LEGACY
1143	bool "Support for deprecated /dev/mcelog character device"
1144	depends on X86_MCE
1145	help
1146	  Enable support for /dev/mcelog which is needed by the old mcelog
1147	  userspace logging daemon. Consider switching to the new generation
1148	  rasdaemon solution.
1149
1150config X86_MCE_INTEL
1151	def_bool y
1152	prompt "Intel MCE features"
1153	depends on X86_MCE && X86_LOCAL_APIC
1154	help
1155	  Additional support for intel specific MCE features such as
1156	  the thermal monitor.
1157
1158config X86_MCE_AMD
1159	def_bool y
1160	prompt "AMD MCE features"
1161	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1162	help
1163	  Additional support for AMD specific MCE features such as
1164	  the DRAM Error Threshold.
1165
1166config X86_ANCIENT_MCE
1167	bool "Support for old Pentium 5 / WinChip machine checks"
1168	depends on X86_32 && X86_MCE
1169	help
1170	  Include support for machine check handling on old Pentium 5 or WinChip
1171	  systems. These typically need to be enabled explicitly on the command
1172	  line.
1173
1174config X86_MCE_THRESHOLD
1175	depends on X86_MCE_AMD || X86_MCE_INTEL
1176	def_bool y
1177
1178config X86_MCE_INJECT
1179	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1180	tristate "Machine check injector support"
1181	help
1182	  Provide support for injecting machine checks for testing purposes.
1183	  If you don't know what a machine check is and you don't do kernel
1184	  QA it is safe to say n.
1185
1186source "arch/x86/events/Kconfig"
1187
1188config X86_LEGACY_VM86
1189	bool "Legacy VM86 support"
1190	depends on X86_32
1191	help
1192	  This option allows user programs to put the CPU into V8086
1193	  mode, which is an 80286-era approximation of 16-bit real mode.
1194
1195	  Some very old versions of X and/or vbetool require this option
1196	  for user mode setting.  Similarly, DOSEMU will use it if
1197	  available to accelerate real mode DOS programs.  However, any
1198	  recent version of DOSEMU, X, or vbetool should be fully
1199	  functional even without kernel VM86 support, as they will all
1200	  fall back to software emulation. Nevertheless, if you are using
1201	  a 16-bit DOS program where 16-bit performance matters, vm86
1202	  mode might be faster than emulation and you might want to
1203	  enable this option.
1204
1205	  Note that any app that works on a 64-bit kernel is unlikely to
1206	  need this option, as 64-bit kernels don't, and can't, support
1207	  V8086 mode. This option is also unrelated to 16-bit protected
1208	  mode and is not needed to run most 16-bit programs under Wine.
1209
1210	  Enabling this option increases the complexity of the kernel
1211	  and slows down exception handling a tiny bit.
1212
1213	  If unsure, say N here.
1214
1215config VM86
1216	bool
1217	default X86_LEGACY_VM86
1218
1219config X86_16BIT
1220	bool "Enable support for 16-bit segments" if EXPERT
1221	default y
1222	depends on MODIFY_LDT_SYSCALL
1223	help
1224	  This option is required by programs like Wine to run 16-bit
1225	  protected mode legacy code on x86 processors.  Disabling
1226	  this option saves about 300 bytes on i386, or around 6K text
1227	  plus 16K runtime memory on x86-64,
1228
1229config X86_ESPFIX32
1230	def_bool y
1231	depends on X86_16BIT && X86_32
1232
1233config X86_ESPFIX64
1234	def_bool y
1235	depends on X86_16BIT && X86_64
1236
1237config X86_VSYSCALL_EMULATION
1238	bool "Enable vsyscall emulation" if EXPERT
1239	default y
1240	depends on X86_64
1241	help
1242	  This enables emulation of the legacy vsyscall page.  Disabling
1243	  it is roughly equivalent to booting with vsyscall=none, except
1244	  that it will also disable the helpful warning if a program
1245	  tries to use a vsyscall.  With this option set to N, offending
1246	  programs will just segfault, citing addresses of the form
1247	  0xffffffffff600?00.
1248
1249	  This option is required by many programs built before 2013, and
1250	  care should be used even with newer programs if set to N.
1251
1252	  Disabling this option saves about 7K of kernel size and
1253	  possibly 4K of additional runtime pagetable memory.
1254
1255config X86_IOPL_IOPERM
1256	bool "IOPERM and IOPL Emulation"
1257	default y
1258	help
1259	  This enables the ioperm() and iopl() syscalls which are necessary
1260	  for legacy applications.
1261
1262	  Legacy IOPL support is an overbroad mechanism which allows user
1263	  space aside of accessing all 65536 I/O ports also to disable
1264	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1265	  capabilities and permission from potentially active security
1266	  modules.
1267
1268	  The emulation restricts the functionality of the syscall to
1269	  only allowing the full range I/O port access, but prevents the
1270	  ability to disable interrupts from user space which would be
1271	  granted if the hardware IOPL mechanism would be used.
1272
1273config TOSHIBA
1274	tristate "Toshiba Laptop support"
1275	depends on X86_32
1276	help
1277	  This adds a driver to safely access the System Management Mode of
1278	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1279	  not work on models with a Phoenix BIOS. The System Management Mode
1280	  is used to set the BIOS and power saving options on Toshiba portables.
1281
1282	  For information on utilities to make use of this driver see the
1283	  Toshiba Linux utilities web site at:
1284	  <http://www.buzzard.org.uk/toshiba/>.
1285
1286	  Say Y if you intend to run this kernel on a Toshiba portable.
1287	  Say N otherwise.
1288
1289config X86_REBOOTFIXUPS
1290	bool "Enable X86 board specific fixups for reboot"
1291	depends on X86_32
1292	help
1293	  This enables chipset and/or board specific fixups to be done
1294	  in order to get reboot to work correctly. This is only needed on
1295	  some combinations of hardware and BIOS. The symptom, for which
1296	  this config is intended, is when reboot ends with a stalled/hung
1297	  system.
1298
1299	  Currently, the only fixup is for the Geode machines using
1300	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1301
1302	  Say Y if you want to enable the fixup. Currently, it's safe to
1303	  enable this option even if you don't need it.
1304	  Say N otherwise.
1305
1306config MICROCODE
1307	bool "CPU microcode loading support"
1308	default y
1309	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1310	help
1311	  If you say Y here, you will be able to update the microcode on
1312	  Intel and AMD processors. The Intel support is for the IA32 family,
1313	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1314	  AMD support is for families 0x10 and later. You will obviously need
1315	  the actual microcode binary data itself which is not shipped with
1316	  the Linux kernel.
1317
1318	  The preferred method to load microcode from a detached initrd is described
1319	  in Documentation/x86/microcode.rst. For that you need to enable
1320	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1321	  initrd for microcode blobs.
1322
1323	  In addition, you can build the microcode into the kernel. For that you
1324	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1325	  config option.
1326
1327config MICROCODE_INTEL
1328	bool "Intel microcode loading support"
1329	depends on CPU_SUP_INTEL && MICROCODE
1330	default MICROCODE
1331	help
1332	  This options enables microcode patch loading support for Intel
1333	  processors.
1334
1335	  For the current Intel microcode data package go to
1336	  <https://downloadcenter.intel.com> and search for
1337	  'Linux Processor Microcode Data File'.
1338
1339config MICROCODE_AMD
1340	bool "AMD microcode loading support"
1341	depends on CPU_SUP_AMD && MICROCODE
1342	help
1343	  If you select this option, microcode patch loading support for AMD
1344	  processors will be enabled.
1345
1346config MICROCODE_LATE_LOADING
1347	bool "Late microcode loading (DANGEROUS)"
1348	default n
1349	depends on MICROCODE
1350	help
1351	  Loading microcode late, when the system is up and executing instructions
1352	  is a tricky business and should be avoided if possible. Just the sequence
1353	  of synchronizing all cores and SMT threads is one fragile dance which does
1354	  not guarantee that cores might not softlock after the loading. Therefore,
1355	  use this at your own risk. Late loading taints the kernel too.
1356
1357config X86_MSR
1358	tristate "/dev/cpu/*/msr - Model-specific register support"
1359	help
1360	  This device gives privileged processes access to the x86
1361	  Model-Specific Registers (MSRs).  It is a character device with
1362	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1363	  MSR accesses are directed to a specific CPU on multi-processor
1364	  systems.
1365
1366config X86_CPUID
1367	tristate "/dev/cpu/*/cpuid - CPU information support"
1368	help
1369	  This device gives processes access to the x86 CPUID instruction to
1370	  be executed on a specific processor.  It is a character device
1371	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1372	  /dev/cpu/31/cpuid.
1373
1374choice
1375	prompt "High Memory Support"
1376	default HIGHMEM4G
1377	depends on X86_32
1378
1379config NOHIGHMEM
1380	bool "off"
1381	help
1382	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1383	  However, the address space of 32-bit x86 processors is only 4
1384	  Gigabytes large. That means that, if you have a large amount of
1385	  physical memory, not all of it can be "permanently mapped" by the
1386	  kernel. The physical memory that's not permanently mapped is called
1387	  "high memory".
1388
1389	  If you are compiling a kernel which will never run on a machine with
1390	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1391	  choice and suitable for most users). This will result in a "3GB/1GB"
1392	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1393	  space and the remaining part of the 4GB virtual memory space is used
1394	  by the kernel to permanently map as much physical memory as
1395	  possible.
1396
1397	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1398	  answer "4GB" here.
1399
1400	  If more than 4 Gigabytes is used then answer "64GB" here. This
1401	  selection turns Intel PAE (Physical Address Extension) mode on.
1402	  PAE implements 3-level paging on IA32 processors. PAE is fully
1403	  supported by Linux, PAE mode is implemented on all recent Intel
1404	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1405	  then the kernel will not boot on CPUs that don't support PAE!
1406
1407	  The actual amount of total physical memory will either be
1408	  auto detected or can be forced by using a kernel command line option
1409	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1410	  your boot loader (lilo or loadlin) about how to pass options to the
1411	  kernel at boot time.)
1412
1413	  If unsure, say "off".
1414
1415config HIGHMEM4G
1416	bool "4GB"
1417	help
1418	  Select this if you have a 32-bit processor and between 1 and 4
1419	  gigabytes of physical RAM.
1420
1421config HIGHMEM64G
1422	bool "64GB"
1423	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1424	select X86_PAE
1425	help
1426	  Select this if you have a 32-bit processor and more than 4
1427	  gigabytes of physical RAM.
1428
1429endchoice
1430
1431choice
1432	prompt "Memory split" if EXPERT
1433	default VMSPLIT_3G
1434	depends on X86_32
1435	help
1436	  Select the desired split between kernel and user memory.
1437
1438	  If the address range available to the kernel is less than the
1439	  physical memory installed, the remaining memory will be available
1440	  as "high memory". Accessing high memory is a little more costly
1441	  than low memory, as it needs to be mapped into the kernel first.
1442	  Note that increasing the kernel address space limits the range
1443	  available to user programs, making the address space there
1444	  tighter.  Selecting anything other than the default 3G/1G split
1445	  will also likely make your kernel incompatible with binary-only
1446	  kernel modules.
1447
1448	  If you are not absolutely sure what you are doing, leave this
1449	  option alone!
1450
1451	config VMSPLIT_3G
1452		bool "3G/1G user/kernel split"
1453	config VMSPLIT_3G_OPT
1454		depends on !X86_PAE
1455		bool "3G/1G user/kernel split (for full 1G low memory)"
1456	config VMSPLIT_2G
1457		bool "2G/2G user/kernel split"
1458	config VMSPLIT_2G_OPT
1459		depends on !X86_PAE
1460		bool "2G/2G user/kernel split (for full 2G low memory)"
1461	config VMSPLIT_1G
1462		bool "1G/3G user/kernel split"
1463endchoice
1464
1465config PAGE_OFFSET
1466	hex
1467	default 0xB0000000 if VMSPLIT_3G_OPT
1468	default 0x80000000 if VMSPLIT_2G
1469	default 0x78000000 if VMSPLIT_2G_OPT
1470	default 0x40000000 if VMSPLIT_1G
1471	default 0xC0000000
1472	depends on X86_32
1473
1474config HIGHMEM
1475	def_bool y
1476	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1477
1478config X86_PAE
1479	bool "PAE (Physical Address Extension) Support"
1480	depends on X86_32 && !HIGHMEM4G
1481	select PHYS_ADDR_T_64BIT
1482	select SWIOTLB
1483	help
1484	  PAE is required for NX support, and furthermore enables
1485	  larger swapspace support for non-overcommit purposes. It
1486	  has the cost of more pagetable lookup overhead, and also
1487	  consumes more pagetable space per process.
1488
1489config X86_5LEVEL
1490	bool "Enable 5-level page tables support"
1491	default y
1492	select DYNAMIC_MEMORY_LAYOUT
1493	select SPARSEMEM_VMEMMAP
1494	depends on X86_64
1495	help
1496	  5-level paging enables access to larger address space:
1497	  upto 128 PiB of virtual address space and 4 PiB of
1498	  physical address space.
1499
1500	  It will be supported by future Intel CPUs.
1501
1502	  A kernel with the option enabled can be booted on machines that
1503	  support 4- or 5-level paging.
1504
1505	  See Documentation/x86/x86_64/5level-paging.rst for more
1506	  information.
1507
1508	  Say N if unsure.
1509
1510config X86_DIRECT_GBPAGES
1511	def_bool y
1512	depends on X86_64
1513	help
1514	  Certain kernel features effectively disable kernel
1515	  linear 1 GB mappings (even if the CPU otherwise
1516	  supports them), so don't confuse the user by printing
1517	  that we have them enabled.
1518
1519config X86_CPA_STATISTICS
1520	bool "Enable statistic for Change Page Attribute"
1521	depends on DEBUG_FS
1522	help
1523	  Expose statistics about the Change Page Attribute mechanism, which
1524	  helps to determine the effectiveness of preserving large and huge
1525	  page mappings when mapping protections are changed.
1526
1527config X86_MEM_ENCRYPT
1528	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1529	select DYNAMIC_PHYSICAL_MASK
1530	def_bool n
1531
1532config AMD_MEM_ENCRYPT
1533	bool "AMD Secure Memory Encryption (SME) support"
1534	depends on X86_64 && CPU_SUP_AMD
1535	select DMA_COHERENT_POOL
1536	select ARCH_USE_MEMREMAP_PROT
1537	select INSTRUCTION_DECODER
1538	select ARCH_HAS_CC_PLATFORM
1539	select X86_MEM_ENCRYPT
1540	help
1541	  Say yes to enable support for the encryption of system memory.
1542	  This requires an AMD processor that supports Secure Memory
1543	  Encryption (SME).
1544
1545config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1546	bool "Activate AMD Secure Memory Encryption (SME) by default"
1547	depends on AMD_MEM_ENCRYPT
1548	help
1549	  Say yes to have system memory encrypted by default if running on
1550	  an AMD processor that supports Secure Memory Encryption (SME).
1551
1552	  If set to Y, then the encryption of system memory can be
1553	  deactivated with the mem_encrypt=off command line option.
1554
1555	  If set to N, then the encryption of system memory can be
1556	  activated with the mem_encrypt=on command line option.
1557
1558# Common NUMA Features
1559config NUMA
1560	bool "NUMA Memory Allocation and Scheduler Support"
1561	depends on SMP
1562	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1563	default y if X86_BIGSMP
1564	select USE_PERCPU_NUMA_NODE_ID
1565	help
1566	  Enable NUMA (Non-Uniform Memory Access) support.
1567
1568	  The kernel will try to allocate memory used by a CPU on the
1569	  local memory controller of the CPU and add some more
1570	  NUMA awareness to the kernel.
1571
1572	  For 64-bit this is recommended if the system is Intel Core i7
1573	  (or later), AMD Opteron, or EM64T NUMA.
1574
1575	  For 32-bit this is only needed if you boot a 32-bit
1576	  kernel on a 64-bit NUMA platform.
1577
1578	  Otherwise, you should say N.
1579
1580config AMD_NUMA
1581	def_bool y
1582	prompt "Old style AMD Opteron NUMA detection"
1583	depends on X86_64 && NUMA && PCI
1584	help
1585	  Enable AMD NUMA node topology detection.  You should say Y here if
1586	  you have a multi processor AMD system. This uses an old method to
1587	  read the NUMA configuration directly from the builtin Northbridge
1588	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1589	  which also takes priority if both are compiled in.
1590
1591config X86_64_ACPI_NUMA
1592	def_bool y
1593	prompt "ACPI NUMA detection"
1594	depends on X86_64 && NUMA && ACPI && PCI
1595	select ACPI_NUMA
1596	help
1597	  Enable ACPI SRAT based node topology detection.
1598
1599config NUMA_EMU
1600	bool "NUMA emulation"
1601	depends on NUMA
1602	help
1603	  Enable NUMA emulation. A flat machine will be split
1604	  into virtual nodes when booted with "numa=fake=N", where N is the
1605	  number of nodes. This is only useful for debugging.
1606
1607config NODES_SHIFT
1608	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1609	range 1 10
1610	default "10" if MAXSMP
1611	default "6" if X86_64
1612	default "3"
1613	depends on NUMA
1614	help
1615	  Specify the maximum number of NUMA Nodes available on the target
1616	  system.  Increases memory reserved to accommodate various tables.
1617
1618config ARCH_FLATMEM_ENABLE
1619	def_bool y
1620	depends on X86_32 && !NUMA
1621
1622config ARCH_SPARSEMEM_ENABLE
1623	def_bool y
1624	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1625	select SPARSEMEM_STATIC if X86_32
1626	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1627
1628config ARCH_SPARSEMEM_DEFAULT
1629	def_bool X86_64 || (NUMA && X86_32)
1630
1631config ARCH_SELECT_MEMORY_MODEL
1632	def_bool y
1633	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1634
1635config ARCH_MEMORY_PROBE
1636	bool "Enable sysfs memory/probe interface"
1637	depends on MEMORY_HOTPLUG
1638	help
1639	  This option enables a sysfs memory/probe interface for testing.
1640	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1641	  If you are unsure how to answer this question, answer N.
1642
1643config ARCH_PROC_KCORE_TEXT
1644	def_bool y
1645	depends on X86_64 && PROC_KCORE
1646
1647config ILLEGAL_POINTER_VALUE
1648	hex
1649	default 0 if X86_32
1650	default 0xdead000000000000 if X86_64
1651
1652config X86_PMEM_LEGACY_DEVICE
1653	bool
1654
1655config X86_PMEM_LEGACY
1656	tristate "Support non-standard NVDIMMs and ADR protected memory"
1657	depends on PHYS_ADDR_T_64BIT
1658	depends on BLK_DEV
1659	select X86_PMEM_LEGACY_DEVICE
1660	select NUMA_KEEP_MEMINFO if NUMA
1661	select LIBNVDIMM
1662	help
1663	  Treat memory marked using the non-standard e820 type of 12 as used
1664	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1665	  The kernel will offer these regions to the 'pmem' driver so
1666	  they can be used for persistent storage.
1667
1668	  Say Y if unsure.
1669
1670config HIGHPTE
1671	bool "Allocate 3rd-level pagetables from highmem"
1672	depends on HIGHMEM
1673	help
1674	  The VM uses one page table entry for each page of physical memory.
1675	  For systems with a lot of RAM, this can be wasteful of precious
1676	  low memory.  Setting this option will put user-space page table
1677	  entries in high memory.
1678
1679config X86_CHECK_BIOS_CORRUPTION
1680	bool "Check for low memory corruption"
1681	help
1682	  Periodically check for memory corruption in low memory, which
1683	  is suspected to be caused by BIOS.  Even when enabled in the
1684	  configuration, it is disabled at runtime.  Enable it by
1685	  setting "memory_corruption_check=1" on the kernel command
1686	  line.  By default it scans the low 64k of memory every 60
1687	  seconds; see the memory_corruption_check_size and
1688	  memory_corruption_check_period parameters in
1689	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1690
1691	  When enabled with the default parameters, this option has
1692	  almost no overhead, as it reserves a relatively small amount
1693	  of memory and scans it infrequently.  It both detects corruption
1694	  and prevents it from affecting the running system.
1695
1696	  It is, however, intended as a diagnostic tool; if repeatable
1697	  BIOS-originated corruption always affects the same memory,
1698	  you can use memmap= to prevent the kernel from using that
1699	  memory.
1700
1701config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1702	bool "Set the default setting of memory_corruption_check"
1703	depends on X86_CHECK_BIOS_CORRUPTION
1704	default y
1705	help
1706	  Set whether the default state of memory_corruption_check is
1707	  on or off.
1708
1709config MATH_EMULATION
1710	bool
1711	depends on MODIFY_LDT_SYSCALL
1712	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1713	help
1714	  Linux can emulate a math coprocessor (used for floating point
1715	  operations) if you don't have one. 486DX and Pentium processors have
1716	  a math coprocessor built in, 486SX and 386 do not, unless you added
1717	  a 487DX or 387, respectively. (The messages during boot time can
1718	  give you some hints here ["man dmesg"].) Everyone needs either a
1719	  coprocessor or this emulation.
1720
1721	  If you don't have a math coprocessor, you need to say Y here; if you
1722	  say Y here even though you have a coprocessor, the coprocessor will
1723	  be used nevertheless. (This behavior can be changed with the kernel
1724	  command line option "no387", which comes handy if your coprocessor
1725	  is broken. Try "man bootparam" or see the documentation of your boot
1726	  loader (lilo or loadlin) about how to pass options to the kernel at
1727	  boot time.) This means that it is a good idea to say Y here if you
1728	  intend to use this kernel on different machines.
1729
1730	  More information about the internals of the Linux math coprocessor
1731	  emulation can be found in <file:arch/x86/math-emu/README>.
1732
1733	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1734	  kernel, it won't hurt.
1735
1736config MTRR
1737	def_bool y
1738	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1739	help
1740	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1741	  the Memory Type Range Registers (MTRRs) may be used to control
1742	  processor access to memory ranges. This is most useful if you have
1743	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1744	  allows bus write transfers to be combined into a larger transfer
1745	  before bursting over the PCI/AGP bus. This can increase performance
1746	  of image write operations 2.5 times or more. Saying Y here creates a
1747	  /proc/mtrr file which may be used to manipulate your processor's
1748	  MTRRs. Typically the X server should use this.
1749
1750	  This code has a reasonably generic interface so that similar
1751	  control registers on other processors can be easily supported
1752	  as well:
1753
1754	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1755	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1756	  these, the ARRs are used to emulate the MTRRs.
1757	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1758	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1759	  write-combining. All of these processors are supported by this code
1760	  and it makes sense to say Y here if you have one of them.
1761
1762	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1763	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1764	  can lead to all sorts of problems, so it's good to say Y here.
1765
1766	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1767	  just add about 9 KB to your kernel.
1768
1769	  See <file:Documentation/x86/mtrr.rst> for more information.
1770
1771config MTRR_SANITIZER
1772	def_bool y
1773	prompt "MTRR cleanup support"
1774	depends on MTRR
1775	help
1776	  Convert MTRR layout from continuous to discrete, so X drivers can
1777	  add writeback entries.
1778
1779	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1780	  The largest mtrr entry size for a continuous block can be set with
1781	  mtrr_chunk_size.
1782
1783	  If unsure, say Y.
1784
1785config MTRR_SANITIZER_ENABLE_DEFAULT
1786	int "MTRR cleanup enable value (0-1)"
1787	range 0 1
1788	default "0"
1789	depends on MTRR_SANITIZER
1790	help
1791	  Enable mtrr cleanup default value
1792
1793config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1794	int "MTRR cleanup spare reg num (0-7)"
1795	range 0 7
1796	default "1"
1797	depends on MTRR_SANITIZER
1798	help
1799	  mtrr cleanup spare entries default, it can be changed via
1800	  mtrr_spare_reg_nr=N on the kernel command line.
1801
1802config X86_PAT
1803	def_bool y
1804	prompt "x86 PAT support" if EXPERT
1805	depends on MTRR
1806	help
1807	  Use PAT attributes to setup page level cache control.
1808
1809	  PATs are the modern equivalents of MTRRs and are much more
1810	  flexible than MTRRs.
1811
1812	  Say N here if you see bootup problems (boot crash, boot hang,
1813	  spontaneous reboots) or a non-working video driver.
1814
1815	  If unsure, say Y.
1816
1817config ARCH_USES_PG_UNCACHED
1818	def_bool y
1819	depends on X86_PAT
1820
1821config X86_UMIP
1822	def_bool y
1823	prompt "User Mode Instruction Prevention" if EXPERT
1824	help
1825	  User Mode Instruction Prevention (UMIP) is a security feature in
1826	  some x86 processors. If enabled, a general protection fault is
1827	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1828	  executed in user mode. These instructions unnecessarily expose
1829	  information about the hardware state.
1830
1831	  The vast majority of applications do not use these instructions.
1832	  For the very few that do, software emulation is provided in
1833	  specific cases in protected and virtual-8086 modes. Emulated
1834	  results are dummy.
1835
1836config CC_HAS_IBT
1837	# GCC >= 9 and binutils >= 2.29
1838	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1839	# Clang/LLVM >= 14
1840	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1841	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1842	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1843		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1844		  $(as-instr,endbr64)
1845
1846config X86_KERNEL_IBT
1847	prompt "Indirect Branch Tracking"
1848	bool
1849	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1850	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1851	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1852	select OBJTOOL
1853	help
1854	  Build the kernel with support for Indirect Branch Tracking, a
1855	  hardware support course-grain forward-edge Control Flow Integrity
1856	  protection. It enforces that all indirect calls must land on
1857	  an ENDBR instruction, as such, the compiler will instrument the
1858	  code with them to make this happen.
1859
1860	  In addition to building the kernel with IBT, seal all functions that
1861	  are not indirect call targets, avoiding them ever becoming one.
1862
1863	  This requires LTO like objtool runs and will slow down the build. It
1864	  does significantly reduce the number of ENDBR instructions in the
1865	  kernel image.
1866
1867config X86_INTEL_MEMORY_PROTECTION_KEYS
1868	prompt "Memory Protection Keys"
1869	def_bool y
1870	# Note: only available in 64-bit mode
1871	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1872	select ARCH_USES_HIGH_VMA_FLAGS
1873	select ARCH_HAS_PKEYS
1874	help
1875	  Memory Protection Keys provides a mechanism for enforcing
1876	  page-based protections, but without requiring modification of the
1877	  page tables when an application changes protection domains.
1878
1879	  For details, see Documentation/core-api/protection-keys.rst
1880
1881	  If unsure, say y.
1882
1883choice
1884	prompt "TSX enable mode"
1885	depends on CPU_SUP_INTEL
1886	default X86_INTEL_TSX_MODE_OFF
1887	help
1888	  Intel's TSX (Transactional Synchronization Extensions) feature
1889	  allows to optimize locking protocols through lock elision which
1890	  can lead to a noticeable performance boost.
1891
1892	  On the other hand it has been shown that TSX can be exploited
1893	  to form side channel attacks (e.g. TAA) and chances are there
1894	  will be more of those attacks discovered in the future.
1895
1896	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1897	  might override this decision by tsx=on the command line parameter.
1898	  Even with TSX enabled, the kernel will attempt to enable the best
1899	  possible TAA mitigation setting depending on the microcode available
1900	  for the particular machine.
1901
1902	  This option allows to set the default tsx mode between tsx=on, =off
1903	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1904	  details.
1905
1906	  Say off if not sure, auto if TSX is in use but it should be used on safe
1907	  platforms or on if TSX is in use and the security aspect of tsx is not
1908	  relevant.
1909
1910config X86_INTEL_TSX_MODE_OFF
1911	bool "off"
1912	help
1913	  TSX is disabled if possible - equals to tsx=off command line parameter.
1914
1915config X86_INTEL_TSX_MODE_ON
1916	bool "on"
1917	help
1918	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1919	  line parameter.
1920
1921config X86_INTEL_TSX_MODE_AUTO
1922	bool "auto"
1923	help
1924	  TSX is enabled on TSX capable HW that is believed to be safe against
1925	  side channel attacks- equals the tsx=auto command line parameter.
1926endchoice
1927
1928config X86_SGX
1929	bool "Software Guard eXtensions (SGX)"
1930	depends on X86_64 && CPU_SUP_INTEL
1931	depends on CRYPTO=y
1932	depends on CRYPTO_SHA256=y
1933	select SRCU
1934	select MMU_NOTIFIER
1935	select NUMA_KEEP_MEMINFO if NUMA
1936	select XARRAY_MULTI
1937	help
1938	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1939	  that can be used by applications to set aside private regions of code
1940	  and data, referred to as enclaves. An enclave's private memory can
1941	  only be accessed by code running within the enclave. Accesses from
1942	  outside the enclave, including other enclaves, are disallowed by
1943	  hardware.
1944
1945	  If unsure, say N.
1946
1947config EFI
1948	bool "EFI runtime service support"
1949	depends on ACPI
1950	select UCS2_STRING
1951	select EFI_RUNTIME_WRAPPERS
1952	select ARCH_USE_MEMREMAP_PROT
1953	help
1954	  This enables the kernel to use EFI runtime services that are
1955	  available (such as the EFI variable services).
1956
1957	  This option is only useful on systems that have EFI firmware.
1958	  In addition, you should use the latest ELILO loader available
1959	  at <http://elilo.sourceforge.net> in order to take advantage
1960	  of EFI runtime services. However, even with this option, the
1961	  resultant kernel should continue to boot on existing non-EFI
1962	  platforms.
1963
1964config EFI_STUB
1965	bool "EFI stub support"
1966	depends on EFI
1967	depends on $(cc-option,-mabi=ms) || X86_32
1968	select RELOCATABLE
1969	help
1970	  This kernel feature allows a bzImage to be loaded directly
1971	  by EFI firmware without the use of a bootloader.
1972
1973	  See Documentation/admin-guide/efi-stub.rst for more information.
1974
1975config EFI_MIXED
1976	bool "EFI mixed-mode support"
1977	depends on EFI_STUB && X86_64
1978	help
1979	  Enabling this feature allows a 64-bit kernel to be booted
1980	  on a 32-bit firmware, provided that your CPU supports 64-bit
1981	  mode.
1982
1983	  Note that it is not possible to boot a mixed-mode enabled
1984	  kernel via the EFI boot stub - a bootloader that supports
1985	  the EFI handover protocol must be used.
1986
1987	  If unsure, say N.
1988
1989source "kernel/Kconfig.hz"
1990
1991config KEXEC
1992	bool "kexec system call"
1993	select KEXEC_CORE
1994	help
1995	  kexec is a system call that implements the ability to shutdown your
1996	  current kernel, and to start another kernel.  It is like a reboot
1997	  but it is independent of the system firmware.   And like a reboot
1998	  you can start any kernel with it, not just Linux.
1999
2000	  The name comes from the similarity to the exec system call.
2001
2002	  It is an ongoing process to be certain the hardware in a machine
2003	  is properly shutdown, so do not be surprised if this code does not
2004	  initially work for you.  As of this writing the exact hardware
2005	  interface is strongly in flux, so no good recommendation can be
2006	  made.
2007
2008config KEXEC_FILE
2009	bool "kexec file based system call"
2010	select KEXEC_CORE
2011	select HAVE_IMA_KEXEC if IMA
2012	depends on X86_64
2013	depends on CRYPTO=y
2014	depends on CRYPTO_SHA256=y
2015	help
2016	  This is new version of kexec system call. This system call is
2017	  file based and takes file descriptors as system call argument
2018	  for kernel and initramfs as opposed to list of segments as
2019	  accepted by previous system call.
2020
2021config ARCH_HAS_KEXEC_PURGATORY
2022	def_bool KEXEC_FILE
2023
2024config KEXEC_SIG
2025	bool "Verify kernel signature during kexec_file_load() syscall"
2026	depends on KEXEC_FILE
2027	help
2028
2029	  This option makes the kexec_file_load() syscall check for a valid
2030	  signature of the kernel image.  The image can still be loaded without
2031	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2032	  there's a signature that we can check, then it must be valid.
2033
2034	  In addition to this option, you need to enable signature
2035	  verification for the corresponding kernel image type being
2036	  loaded in order for this to work.
2037
2038config KEXEC_SIG_FORCE
2039	bool "Require a valid signature in kexec_file_load() syscall"
2040	depends on KEXEC_SIG
2041	help
2042	  This option makes kernel signature verification mandatory for
2043	  the kexec_file_load() syscall.
2044
2045config KEXEC_BZIMAGE_VERIFY_SIG
2046	bool "Enable bzImage signature verification support"
2047	depends on KEXEC_SIG
2048	depends on SIGNED_PE_FILE_VERIFICATION
2049	select SYSTEM_TRUSTED_KEYRING
2050	help
2051	  Enable bzImage signature verification support.
2052
2053config CRASH_DUMP
2054	bool "kernel crash dumps"
2055	depends on X86_64 || (X86_32 && HIGHMEM)
2056	help
2057	  Generate crash dump after being started by kexec.
2058	  This should be normally only set in special crash dump kernels
2059	  which are loaded in the main kernel with kexec-tools into
2060	  a specially reserved region and then later executed after
2061	  a crash by kdump/kexec. The crash dump kernel must be compiled
2062	  to a memory address not used by the main kernel or BIOS using
2063	  PHYSICAL_START, or it must be built as a relocatable image
2064	  (CONFIG_RELOCATABLE=y).
2065	  For more details see Documentation/admin-guide/kdump/kdump.rst
2066
2067config KEXEC_JUMP
2068	bool "kexec jump"
2069	depends on KEXEC && HIBERNATION
2070	help
2071	  Jump between original kernel and kexeced kernel and invoke
2072	  code in physical address mode via KEXEC
2073
2074config PHYSICAL_START
2075	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2076	default "0x1000000"
2077	help
2078	  This gives the physical address where the kernel is loaded.
2079
2080	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2081	  bzImage will decompress itself to above physical address and
2082	  run from there. Otherwise, bzImage will run from the address where
2083	  it has been loaded by the boot loader and will ignore above physical
2084	  address.
2085
2086	  In normal kdump cases one does not have to set/change this option
2087	  as now bzImage can be compiled as a completely relocatable image
2088	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2089	  address. This option is mainly useful for the folks who don't want
2090	  to use a bzImage for capturing the crash dump and want to use a
2091	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2092	  to be specifically compiled to run from a specific memory area
2093	  (normally a reserved region) and this option comes handy.
2094
2095	  So if you are using bzImage for capturing the crash dump,
2096	  leave the value here unchanged to 0x1000000 and set
2097	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2098	  for capturing the crash dump change this value to start of
2099	  the reserved region.  In other words, it can be set based on
2100	  the "X" value as specified in the "crashkernel=YM@XM"
2101	  command line boot parameter passed to the panic-ed
2102	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2103	  for more details about crash dumps.
2104
2105	  Usage of bzImage for capturing the crash dump is recommended as
2106	  one does not have to build two kernels. Same kernel can be used
2107	  as production kernel and capture kernel. Above option should have
2108	  gone away after relocatable bzImage support is introduced. But it
2109	  is present because there are users out there who continue to use
2110	  vmlinux for dump capture. This option should go away down the
2111	  line.
2112
2113	  Don't change this unless you know what you are doing.
2114
2115config RELOCATABLE
2116	bool "Build a relocatable kernel"
2117	default y
2118	help
2119	  This builds a kernel image that retains relocation information
2120	  so it can be loaded someplace besides the default 1MB.
2121	  The relocations tend to make the kernel binary about 10% larger,
2122	  but are discarded at runtime.
2123
2124	  One use is for the kexec on panic case where the recovery kernel
2125	  must live at a different physical address than the primary
2126	  kernel.
2127
2128	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2129	  it has been loaded at and the compile time physical address
2130	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2131
2132config RANDOMIZE_BASE
2133	bool "Randomize the address of the kernel image (KASLR)"
2134	depends on RELOCATABLE
2135	default y
2136	help
2137	  In support of Kernel Address Space Layout Randomization (KASLR),
2138	  this randomizes the physical address at which the kernel image
2139	  is decompressed and the virtual address where the kernel
2140	  image is mapped, as a security feature that deters exploit
2141	  attempts relying on knowledge of the location of kernel
2142	  code internals.
2143
2144	  On 64-bit, the kernel physical and virtual addresses are
2145	  randomized separately. The physical address will be anywhere
2146	  between 16MB and the top of physical memory (up to 64TB). The
2147	  virtual address will be randomized from 16MB up to 1GB (9 bits
2148	  of entropy). Note that this also reduces the memory space
2149	  available to kernel modules from 1.5GB to 1GB.
2150
2151	  On 32-bit, the kernel physical and virtual addresses are
2152	  randomized together. They will be randomized from 16MB up to
2153	  512MB (8 bits of entropy).
2154
2155	  Entropy is generated using the RDRAND instruction if it is
2156	  supported. If RDTSC is supported, its value is mixed into
2157	  the entropy pool as well. If neither RDRAND nor RDTSC are
2158	  supported, then entropy is read from the i8254 timer. The
2159	  usable entropy is limited by the kernel being built using
2160	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2161	  minimum of 2MB. As a result, only 10 bits of entropy are
2162	  theoretically possible, but the implementations are further
2163	  limited due to memory layouts.
2164
2165	  If unsure, say Y.
2166
2167# Relocation on x86 needs some additional build support
2168config X86_NEED_RELOCS
2169	def_bool y
2170	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2171
2172config PHYSICAL_ALIGN
2173	hex "Alignment value to which kernel should be aligned"
2174	default "0x200000"
2175	range 0x2000 0x1000000 if X86_32
2176	range 0x200000 0x1000000 if X86_64
2177	help
2178	  This value puts the alignment restrictions on physical address
2179	  where kernel is loaded and run from. Kernel is compiled for an
2180	  address which meets above alignment restriction.
2181
2182	  If bootloader loads the kernel at a non-aligned address and
2183	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2184	  address aligned to above value and run from there.
2185
2186	  If bootloader loads the kernel at a non-aligned address and
2187	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2188	  load address and decompress itself to the address it has been
2189	  compiled for and run from there. The address for which kernel is
2190	  compiled already meets above alignment restrictions. Hence the
2191	  end result is that kernel runs from a physical address meeting
2192	  above alignment restrictions.
2193
2194	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2195	  this value must be a multiple of 0x200000.
2196
2197	  Don't change this unless you know what you are doing.
2198
2199config DYNAMIC_MEMORY_LAYOUT
2200	bool
2201	help
2202	  This option makes base addresses of vmalloc and vmemmap as well as
2203	  __PAGE_OFFSET movable during boot.
2204
2205config RANDOMIZE_MEMORY
2206	bool "Randomize the kernel memory sections"
2207	depends on X86_64
2208	depends on RANDOMIZE_BASE
2209	select DYNAMIC_MEMORY_LAYOUT
2210	default RANDOMIZE_BASE
2211	help
2212	  Randomizes the base virtual address of kernel memory sections
2213	  (physical memory mapping, vmalloc & vmemmap). This security feature
2214	  makes exploits relying on predictable memory locations less reliable.
2215
2216	  The order of allocations remains unchanged. Entropy is generated in
2217	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2218	  configuration have in average 30,000 different possible virtual
2219	  addresses for each memory section.
2220
2221	  If unsure, say Y.
2222
2223config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2224	hex "Physical memory mapping padding" if EXPERT
2225	depends on RANDOMIZE_MEMORY
2226	default "0xa" if MEMORY_HOTPLUG
2227	default "0x0"
2228	range 0x1 0x40 if MEMORY_HOTPLUG
2229	range 0x0 0x40
2230	help
2231	  Define the padding in terabytes added to the existing physical
2232	  memory size during kernel memory randomization. It is useful
2233	  for memory hotplug support but reduces the entropy available for
2234	  address randomization.
2235
2236	  If unsure, leave at the default value.
2237
2238config HOTPLUG_CPU
2239	def_bool y
2240	depends on SMP
2241
2242config BOOTPARAM_HOTPLUG_CPU0
2243	bool "Set default setting of cpu0_hotpluggable"
2244	depends on HOTPLUG_CPU
2245	help
2246	  Set whether default state of cpu0_hotpluggable is on or off.
2247
2248	  Say Y here to enable CPU0 hotplug by default. If this switch
2249	  is turned on, there is no need to give cpu0_hotplug kernel
2250	  parameter and the CPU0 hotplug feature is enabled by default.
2251
2252	  Please note: there are two known CPU0 dependencies if you want
2253	  to enable the CPU0 hotplug feature either by this switch or by
2254	  cpu0_hotplug kernel parameter.
2255
2256	  First, resume from hibernate or suspend always starts from CPU0.
2257	  So hibernate and suspend are prevented if CPU0 is offline.
2258
2259	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2260	  offline if any interrupt can not migrate out of CPU0. There may
2261	  be other CPU0 dependencies.
2262
2263	  Please make sure the dependencies are under your control before
2264	  you enable this feature.
2265
2266	  Say N if you don't want to enable CPU0 hotplug feature by default.
2267	  You still can enable the CPU0 hotplug feature at boot by kernel
2268	  parameter cpu0_hotplug.
2269
2270config DEBUG_HOTPLUG_CPU0
2271	def_bool n
2272	prompt "Debug CPU0 hotplug"
2273	depends on HOTPLUG_CPU
2274	help
2275	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2276	  soon as possible and boots up userspace with CPU0 offlined. User
2277	  can online CPU0 back after boot time.
2278
2279	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2280	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2281	  compilation or giving cpu0_hotplug kernel parameter at boot.
2282
2283	  If unsure, say N.
2284
2285config COMPAT_VDSO
2286	def_bool n
2287	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2288	depends on COMPAT_32
2289	help
2290	  Certain buggy versions of glibc will crash if they are
2291	  presented with a 32-bit vDSO that is not mapped at the address
2292	  indicated in its segment table.
2293
2294	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2295	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2296	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2297	  the only released version with the bug, but OpenSUSE 9
2298	  contains a buggy "glibc 2.3.2".
2299
2300	  The symptom of the bug is that everything crashes on startup, saying:
2301	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2302
2303	  Saying Y here changes the default value of the vdso32 boot
2304	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2305	  This works around the glibc bug but hurts performance.
2306
2307	  If unsure, say N: if you are compiling your own kernel, you
2308	  are unlikely to be using a buggy version of glibc.
2309
2310choice
2311	prompt "vsyscall table for legacy applications"
2312	depends on X86_64
2313	default LEGACY_VSYSCALL_XONLY
2314	help
2315	  Legacy user code that does not know how to find the vDSO expects
2316	  to be able to issue three syscalls by calling fixed addresses in
2317	  kernel space. Since this location is not randomized with ASLR,
2318	  it can be used to assist security vulnerability exploitation.
2319
2320	  This setting can be changed at boot time via the kernel command
2321	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2322	  is deprecated and can only be enabled using the kernel command
2323	  line.
2324
2325	  On a system with recent enough glibc (2.14 or newer) and no
2326	  static binaries, you can say None without a performance penalty
2327	  to improve security.
2328
2329	  If unsure, select "Emulate execution only".
2330
2331	config LEGACY_VSYSCALL_XONLY
2332		bool "Emulate execution only"
2333		help
2334		  The kernel traps and emulates calls into the fixed vsyscall
2335		  address mapping and does not allow reads.  This
2336		  configuration is recommended when userspace might use the
2337		  legacy vsyscall area but support for legacy binary
2338		  instrumentation of legacy code is not needed.  It mitigates
2339		  certain uses of the vsyscall area as an ASLR-bypassing
2340		  buffer.
2341
2342	config LEGACY_VSYSCALL_NONE
2343		bool "None"
2344		help
2345		  There will be no vsyscall mapping at all. This will
2346		  eliminate any risk of ASLR bypass due to the vsyscall
2347		  fixed address mapping. Attempts to use the vsyscalls
2348		  will be reported to dmesg, so that either old or
2349		  malicious userspace programs can be identified.
2350
2351endchoice
2352
2353config CMDLINE_BOOL
2354	bool "Built-in kernel command line"
2355	help
2356	  Allow for specifying boot arguments to the kernel at
2357	  build time.  On some systems (e.g. embedded ones), it is
2358	  necessary or convenient to provide some or all of the
2359	  kernel boot arguments with the kernel itself (that is,
2360	  to not rely on the boot loader to provide them.)
2361
2362	  To compile command line arguments into the kernel,
2363	  set this option to 'Y', then fill in the
2364	  boot arguments in CONFIG_CMDLINE.
2365
2366	  Systems with fully functional boot loaders (i.e. non-embedded)
2367	  should leave this option set to 'N'.
2368
2369config CMDLINE
2370	string "Built-in kernel command string"
2371	depends on CMDLINE_BOOL
2372	default ""
2373	help
2374	  Enter arguments here that should be compiled into the kernel
2375	  image and used at boot time.  If the boot loader provides a
2376	  command line at boot time, it is appended to this string to
2377	  form the full kernel command line, when the system boots.
2378
2379	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2380	  change this behavior.
2381
2382	  In most cases, the command line (whether built-in or provided
2383	  by the boot loader) should specify the device for the root
2384	  file system.
2385
2386config CMDLINE_OVERRIDE
2387	bool "Built-in command line overrides boot loader arguments"
2388	depends on CMDLINE_BOOL && CMDLINE != ""
2389	help
2390	  Set this option to 'Y' to have the kernel ignore the boot loader
2391	  command line, and use ONLY the built-in command line.
2392
2393	  This is used to work around broken boot loaders.  This should
2394	  be set to 'N' under normal conditions.
2395
2396config MODIFY_LDT_SYSCALL
2397	bool "Enable the LDT (local descriptor table)" if EXPERT
2398	default y
2399	help
2400	  Linux can allow user programs to install a per-process x86
2401	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2402	  call.  This is required to run 16-bit or segmented code such as
2403	  DOSEMU or some Wine programs.  It is also used by some very old
2404	  threading libraries.
2405
2406	  Enabling this feature adds a small amount of overhead to
2407	  context switches and increases the low-level kernel attack
2408	  surface.  Disabling it removes the modify_ldt(2) system call.
2409
2410	  Saying 'N' here may make sense for embedded or server kernels.
2411
2412config STRICT_SIGALTSTACK_SIZE
2413	bool "Enforce strict size checking for sigaltstack"
2414	depends on DYNAMIC_SIGFRAME
2415	help
2416	  For historical reasons MINSIGSTKSZ is a constant which became
2417	  already too small with AVX512 support. Add a mechanism to
2418	  enforce strict checking of the sigaltstack size against the
2419	  real size of the FPU frame. This option enables the check
2420	  by default. It can also be controlled via the kernel command
2421	  line option 'strict_sas_size' independent of this config
2422	  switch. Enabling it might break existing applications which
2423	  allocate a too small sigaltstack but 'work' because they
2424	  never get a signal delivered.
2425
2426	  Say 'N' unless you want to really enforce this check.
2427
2428source "kernel/livepatch/Kconfig"
2429
2430endmenu
2431
2432config CC_HAS_SLS
2433	def_bool $(cc-option,-mharden-sls=all)
2434
2435config CC_HAS_RETURN_THUNK
2436	def_bool $(cc-option,-mfunction-return=thunk-extern)
2437
2438menuconfig SPECULATION_MITIGATIONS
2439	bool "Mitigations for speculative execution vulnerabilities"
2440	default y
2441	help
2442	  Say Y here to enable options which enable mitigations for
2443	  speculative execution hardware vulnerabilities.
2444
2445	  If you say N, all mitigations will be disabled. You really
2446	  should know what you are doing to say so.
2447
2448if SPECULATION_MITIGATIONS
2449
2450config PAGE_TABLE_ISOLATION
2451	bool "Remove the kernel mapping in user mode"
2452	default y
2453	depends on (X86_64 || X86_PAE)
2454	help
2455	  This feature reduces the number of hardware side channels by
2456	  ensuring that the majority of kernel addresses are not mapped
2457	  into userspace.
2458
2459	  See Documentation/x86/pti.rst for more details.
2460
2461config RETPOLINE
2462	bool "Avoid speculative indirect branches in kernel"
2463	select OBJTOOL if HAVE_OBJTOOL
2464	default y
2465	help
2466	  Compile kernel with the retpoline compiler options to guard against
2467	  kernel-to-user data leaks by avoiding speculative indirect
2468	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2469	  support for full protection. The kernel may run slower.
2470
2471config RETHUNK
2472	bool "Enable return-thunks"
2473	depends on RETPOLINE && CC_HAS_RETURN_THUNK
2474	select OBJTOOL if HAVE_OBJTOOL
2475	default y if X86_64
2476	help
2477	  Compile the kernel with the return-thunks compiler option to guard
2478	  against kernel-to-user data leaks by avoiding return speculation.
2479	  Requires a compiler with -mfunction-return=thunk-extern
2480	  support for full protection. The kernel may run slower.
2481
2482config CPU_UNRET_ENTRY
2483	bool "Enable UNRET on kernel entry"
2484	depends on CPU_SUP_AMD && RETHUNK && X86_64
2485	default y
2486	help
2487	  Compile the kernel with support for the retbleed=unret mitigation.
2488
2489config CPU_IBPB_ENTRY
2490	bool "Enable IBPB on kernel entry"
2491	depends on CPU_SUP_AMD && X86_64
2492	default y
2493	help
2494	  Compile the kernel with support for the retbleed=ibpb mitigation.
2495
2496config CPU_IBRS_ENTRY
2497	bool "Enable IBRS on kernel entry"
2498	depends on CPU_SUP_INTEL && X86_64
2499	default y
2500	help
2501	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2502	  This mitigates both spectre_v2 and retbleed at great cost to
2503	  performance.
2504
2505config SLS
2506	bool "Mitigate Straight-Line-Speculation"
2507	depends on CC_HAS_SLS && X86_64
2508	select OBJTOOL if HAVE_OBJTOOL
2509	default n
2510	help
2511	  Compile the kernel with straight-line-speculation options to guard
2512	  against straight line speculation. The kernel image might be slightly
2513	  larger.
2514
2515endif
2516
2517config ARCH_HAS_ADD_PAGES
2518	def_bool y
2519	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2520
2521config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2522	def_bool y
2523
2524menu "Power management and ACPI options"
2525
2526config ARCH_HIBERNATION_HEADER
2527	def_bool y
2528	depends on HIBERNATION
2529
2530source "kernel/power/Kconfig"
2531
2532source "drivers/acpi/Kconfig"
2533
2534config X86_APM_BOOT
2535	def_bool y
2536	depends on APM
2537
2538menuconfig APM
2539	tristate "APM (Advanced Power Management) BIOS support"
2540	depends on X86_32 && PM_SLEEP
2541	help
2542	  APM is a BIOS specification for saving power using several different
2543	  techniques. This is mostly useful for battery powered laptops with
2544	  APM compliant BIOSes. If you say Y here, the system time will be
2545	  reset after a RESUME operation, the /proc/apm device will provide
2546	  battery status information, and user-space programs will receive
2547	  notification of APM "events" (e.g. battery status change).
2548
2549	  If you select "Y" here, you can disable actual use of the APM
2550	  BIOS by passing the "apm=off" option to the kernel at boot time.
2551
2552	  Note that the APM support is almost completely disabled for
2553	  machines with more than one CPU.
2554
2555	  In order to use APM, you will need supporting software. For location
2556	  and more information, read <file:Documentation/power/apm-acpi.rst>
2557	  and the Battery Powered Linux mini-HOWTO, available from
2558	  <http://www.tldp.org/docs.html#howto>.
2559
2560	  This driver does not spin down disk drives (see the hdparm(8)
2561	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2562	  VESA-compliant "green" monitors.
2563
2564	  This driver does not support the TI 4000M TravelMate and the ACER
2565	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2566	  desktop machines also don't have compliant BIOSes, and this driver
2567	  may cause those machines to panic during the boot phase.
2568
2569	  Generally, if you don't have a battery in your machine, there isn't
2570	  much point in using this driver and you should say N. If you get
2571	  random kernel OOPSes or reboots that don't seem to be related to
2572	  anything, try disabling/enabling this option (or disabling/enabling
2573	  APM in your BIOS).
2574
2575	  Some other things you should try when experiencing seemingly random,
2576	  "weird" problems:
2577
2578	  1) make sure that you have enough swap space and that it is
2579	  enabled.
2580	  2) pass the "no-hlt" option to the kernel
2581	  3) switch on floating point emulation in the kernel and pass
2582	  the "no387" option to the kernel
2583	  4) pass the "floppy=nodma" option to the kernel
2584	  5) pass the "mem=4M" option to the kernel (thereby disabling
2585	  all but the first 4 MB of RAM)
2586	  6) make sure that the CPU is not over clocked.
2587	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2588	  8) disable the cache from your BIOS settings
2589	  9) install a fan for the video card or exchange video RAM
2590	  10) install a better fan for the CPU
2591	  11) exchange RAM chips
2592	  12) exchange the motherboard.
2593
2594	  To compile this driver as a module, choose M here: the
2595	  module will be called apm.
2596
2597if APM
2598
2599config APM_IGNORE_USER_SUSPEND
2600	bool "Ignore USER SUSPEND"
2601	help
2602	  This option will ignore USER SUSPEND requests. On machines with a
2603	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2604	  series notebooks, it is necessary to say Y because of a BIOS bug.
2605
2606config APM_DO_ENABLE
2607	bool "Enable PM at boot time"
2608	help
2609	  Enable APM features at boot time. From page 36 of the APM BIOS
2610	  specification: "When disabled, the APM BIOS does not automatically
2611	  power manage devices, enter the Standby State, enter the Suspend
2612	  State, or take power saving steps in response to CPU Idle calls."
2613	  This driver will make CPU Idle calls when Linux is idle (unless this
2614	  feature is turned off -- see "Do CPU IDLE calls", below). This
2615	  should always save battery power, but more complicated APM features
2616	  will be dependent on your BIOS implementation. You may need to turn
2617	  this option off if your computer hangs at boot time when using APM
2618	  support, or if it beeps continuously instead of suspending. Turn
2619	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2620	  T400CDT. This is off by default since most machines do fine without
2621	  this feature.
2622
2623config APM_CPU_IDLE
2624	depends on CPU_IDLE
2625	bool "Make CPU Idle calls when idle"
2626	help
2627	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2628	  On some machines, this can activate improved power savings, such as
2629	  a slowed CPU clock rate, when the machine is idle. These idle calls
2630	  are made after the idle loop has run for some length of time (e.g.,
2631	  333 mS). On some machines, this will cause a hang at boot time or
2632	  whenever the CPU becomes idle. (On machines with more than one CPU,
2633	  this option does nothing.)
2634
2635config APM_DISPLAY_BLANK
2636	bool "Enable console blanking using APM"
2637	help
2638	  Enable console blanking using the APM. Some laptops can use this to
2639	  turn off the LCD backlight when the screen blanker of the Linux
2640	  virtual console blanks the screen. Note that this is only used by
2641	  the virtual console screen blanker, and won't turn off the backlight
2642	  when using the X Window system. This also doesn't have anything to
2643	  do with your VESA-compliant power-saving monitor. Further, this
2644	  option doesn't work for all laptops -- it might not turn off your
2645	  backlight at all, or it might print a lot of errors to the console,
2646	  especially if you are using gpm.
2647
2648config APM_ALLOW_INTS
2649	bool "Allow interrupts during APM BIOS calls"
2650	help
2651	  Normally we disable external interrupts while we are making calls to
2652	  the APM BIOS as a measure to lessen the effects of a badly behaving
2653	  BIOS implementation.  The BIOS should reenable interrupts if it
2654	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2655	  many of the newer IBM Thinkpads.  If you experience hangs when you
2656	  suspend, try setting this to Y.  Otherwise, say N.
2657
2658endif # APM
2659
2660source "drivers/cpufreq/Kconfig"
2661
2662source "drivers/cpuidle/Kconfig"
2663
2664source "drivers/idle/Kconfig"
2665
2666endmenu
2667
2668menu "Bus options (PCI etc.)"
2669
2670choice
2671	prompt "PCI access mode"
2672	depends on X86_32 && PCI
2673	default PCI_GOANY
2674	help
2675	  On PCI systems, the BIOS can be used to detect the PCI devices and
2676	  determine their configuration. However, some old PCI motherboards
2677	  have BIOS bugs and may crash if this is done. Also, some embedded
2678	  PCI-based systems don't have any BIOS at all. Linux can also try to
2679	  detect the PCI hardware directly without using the BIOS.
2680
2681	  With this option, you can specify how Linux should detect the
2682	  PCI devices. If you choose "BIOS", the BIOS will be used,
2683	  if you choose "Direct", the BIOS won't be used, and if you
2684	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2685	  If you choose "Any", the kernel will try MMCONFIG, then the
2686	  direct access method and falls back to the BIOS if that doesn't
2687	  work. If unsure, go with the default, which is "Any".
2688
2689config PCI_GOBIOS
2690	bool "BIOS"
2691
2692config PCI_GOMMCONFIG
2693	bool "MMConfig"
2694
2695config PCI_GODIRECT
2696	bool "Direct"
2697
2698config PCI_GOOLPC
2699	bool "OLPC XO-1"
2700	depends on OLPC
2701
2702config PCI_GOANY
2703	bool "Any"
2704
2705endchoice
2706
2707config PCI_BIOS
2708	def_bool y
2709	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2710
2711# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2712config PCI_DIRECT
2713	def_bool y
2714	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2715
2716config PCI_MMCONFIG
2717	bool "Support mmconfig PCI config space access" if X86_64
2718	default y
2719	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2720	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2721
2722config PCI_OLPC
2723	def_bool y
2724	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2725
2726config PCI_XEN
2727	def_bool y
2728	depends on PCI && XEN
2729
2730config MMCONF_FAM10H
2731	def_bool y
2732	depends on X86_64 && PCI_MMCONFIG && ACPI
2733
2734config PCI_CNB20LE_QUIRK
2735	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2736	depends on PCI
2737	help
2738	  Read the PCI windows out of the CNB20LE host bridge. This allows
2739	  PCI hotplug to work on systems with the CNB20LE chipset which do
2740	  not have ACPI.
2741
2742	  There's no public spec for this chipset, and this functionality
2743	  is known to be incomplete.
2744
2745	  You should say N unless you know you need this.
2746
2747config ISA_BUS
2748	bool "ISA bus support on modern systems" if EXPERT
2749	help
2750	  Expose ISA bus device drivers and options available for selection and
2751	  configuration. Enable this option if your target machine has an ISA
2752	  bus. ISA is an older system, displaced by PCI and newer bus
2753	  architectures -- if your target machine is modern, it probably does
2754	  not have an ISA bus.
2755
2756	  If unsure, say N.
2757
2758# x86_64 have no ISA slots, but can have ISA-style DMA.
2759config ISA_DMA_API
2760	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2761	default y
2762	help
2763	  Enables ISA-style DMA support for devices requiring such controllers.
2764	  If unsure, say Y.
2765
2766if X86_32
2767
2768config ISA
2769	bool "ISA support"
2770	help
2771	  Find out whether you have ISA slots on your motherboard.  ISA is the
2772	  name of a bus system, i.e. the way the CPU talks to the other stuff
2773	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2774	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2775	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2776
2777config SCx200
2778	tristate "NatSemi SCx200 support"
2779	help
2780	  This provides basic support for National Semiconductor's
2781	  (now AMD's) Geode processors.  The driver probes for the
2782	  PCI-IDs of several on-chip devices, so its a good dependency
2783	  for other scx200_* drivers.
2784
2785	  If compiled as a module, the driver is named scx200.
2786
2787config SCx200HR_TIMER
2788	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2789	depends on SCx200
2790	default y
2791	help
2792	  This driver provides a clocksource built upon the on-chip
2793	  27MHz high-resolution timer.  Its also a workaround for
2794	  NSC Geode SC-1100's buggy TSC, which loses time when the
2795	  processor goes idle (as is done by the scheduler).  The
2796	  other workaround is idle=poll boot option.
2797
2798config OLPC
2799	bool "One Laptop Per Child support"
2800	depends on !X86_PAE
2801	select GPIOLIB
2802	select OF
2803	select OF_PROMTREE
2804	select IRQ_DOMAIN
2805	select OLPC_EC
2806	help
2807	  Add support for detecting the unique features of the OLPC
2808	  XO hardware.
2809
2810config OLPC_XO1_PM
2811	bool "OLPC XO-1 Power Management"
2812	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2813	help
2814	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2815
2816config OLPC_XO1_RTC
2817	bool "OLPC XO-1 Real Time Clock"
2818	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2819	help
2820	  Add support for the XO-1 real time clock, which can be used as a
2821	  programmable wakeup source.
2822
2823config OLPC_XO1_SCI
2824	bool "OLPC XO-1 SCI extras"
2825	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2826	depends on INPUT=y
2827	select POWER_SUPPLY
2828	help
2829	  Add support for SCI-based features of the OLPC XO-1 laptop:
2830	   - EC-driven system wakeups
2831	   - Power button
2832	   - Ebook switch
2833	   - Lid switch
2834	   - AC adapter status updates
2835	   - Battery status updates
2836
2837config OLPC_XO15_SCI
2838	bool "OLPC XO-1.5 SCI extras"
2839	depends on OLPC && ACPI
2840	select POWER_SUPPLY
2841	help
2842	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2843	   - EC-driven system wakeups
2844	   - AC adapter status updates
2845	   - Battery status updates
2846
2847config ALIX
2848	bool "PCEngines ALIX System Support (LED setup)"
2849	select GPIOLIB
2850	help
2851	  This option enables system support for the PCEngines ALIX.
2852	  At present this just sets up LEDs for GPIO control on
2853	  ALIX2/3/6 boards.  However, other system specific setup should
2854	  get added here.
2855
2856	  Note: You must still enable the drivers for GPIO and LED support
2857	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2858
2859	  Note: You have to set alix.force=1 for boards with Award BIOS.
2860
2861config NET5501
2862	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2863	select GPIOLIB
2864	help
2865	  This option enables system support for the Soekris Engineering net5501.
2866
2867config GEOS
2868	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2869	select GPIOLIB
2870	depends on DMI
2871	help
2872	  This option enables system support for the Traverse Technologies GEOS.
2873
2874config TS5500
2875	bool "Technologic Systems TS-5500 platform support"
2876	depends on MELAN
2877	select CHECK_SIGNATURE
2878	select NEW_LEDS
2879	select LEDS_CLASS
2880	help
2881	  This option enables system support for the Technologic Systems TS-5500.
2882
2883endif # X86_32
2884
2885config AMD_NB
2886	def_bool y
2887	depends on CPU_SUP_AMD && PCI
2888
2889endmenu
2890
2891menu "Binary Emulations"
2892
2893config IA32_EMULATION
2894	bool "IA32 Emulation"
2895	depends on X86_64
2896	select ARCH_WANT_OLD_COMPAT_IPC
2897	select BINFMT_ELF
2898	select COMPAT_OLD_SIGACTION
2899	help
2900	  Include code to run legacy 32-bit programs under a
2901	  64-bit kernel. You should likely turn this on, unless you're
2902	  100% sure that you don't have any 32-bit programs left.
2903
2904config X86_X32_ABI
2905	bool "x32 ABI for 64-bit mode"
2906	depends on X86_64
2907	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2908	# compressed debug sections to x86_x32 properly:
2909	# https://github.com/ClangBuiltLinux/linux/issues/514
2910	# https://github.com/ClangBuiltLinux/linux/issues/1141
2911	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2912	help
2913	  Include code to run binaries for the x32 native 32-bit ABI
2914	  for 64-bit processors.  An x32 process gets access to the
2915	  full 64-bit register file and wide data path while leaving
2916	  pointers at 32 bits for smaller memory footprint.
2917
2918config COMPAT_32
2919	def_bool y
2920	depends on IA32_EMULATION || X86_32
2921	select HAVE_UID16
2922	select OLD_SIGSUSPEND3
2923
2924config COMPAT
2925	def_bool y
2926	depends on IA32_EMULATION || X86_X32_ABI
2927
2928config COMPAT_FOR_U64_ALIGNMENT
2929	def_bool y
2930	depends on COMPAT
2931
2932endmenu
2933
2934config HAVE_ATOMIC_IOMAP
2935	def_bool y
2936	depends on X86_32
2937
2938source "arch/x86/kvm/Kconfig"
2939
2940source "arch/x86/Kconfig.assembler"
2941