xref: /openbmc/linux/arch/x86/Kconfig (revision fb4a5dfc)
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_UACCESS_FLUSHCACHE	if X86_64
89	select ARCH_HAS_COPY_MC			if X86_64
90	select ARCH_HAS_SET_MEMORY
91	select ARCH_HAS_SET_DIRECT_MAP
92	select ARCH_HAS_STRICT_KERNEL_RWX
93	select ARCH_HAS_STRICT_MODULE_RWX
94	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95	select ARCH_HAS_SYSCALL_WRAPPER
96	select ARCH_HAS_UBSAN_SANITIZE_ALL
97	select ARCH_HAS_DEBUG_WX
98	select ARCH_HAS_ZONE_DMA_SET if EXPERT
99	select ARCH_HAVE_NMI_SAFE_CMPXCHG
100	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
101	select ARCH_MIGHT_HAVE_PC_PARPORT
102	select ARCH_MIGHT_HAVE_PC_SERIO
103	select ARCH_STACKWALK
104	select ARCH_SUPPORTS_ACPI
105	select ARCH_SUPPORTS_ATOMIC_RMW
106	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
107	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
108	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
109	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
110	select ARCH_SUPPORTS_CFI_CLANG		if X86_64
111	select ARCH_USES_CFI_TRAPS		if X86_64 && CFI_CLANG
112	select ARCH_SUPPORTS_LTO_CLANG
113	select ARCH_SUPPORTS_LTO_CLANG_THIN
114	select ARCH_USE_BUILTIN_BSWAP
115	select ARCH_USE_MEMTEST
116	select ARCH_USE_QUEUED_RWLOCKS
117	select ARCH_USE_QUEUED_SPINLOCKS
118	select ARCH_USE_SYM_ANNOTATIONS
119	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
120	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
121	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
122	select ARCH_WANTS_NO_INSTR
123	select ARCH_WANT_GENERAL_HUGETLB
124	select ARCH_WANT_HUGE_PMD_SHARE
125	select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP	if X86_64
126	select ARCH_WANT_LD_ORPHAN_WARN
127	select ARCH_WANTS_THP_SWAP		if X86_64
128	select ARCH_HAS_PARANOID_L1D_FLUSH
129	select BUILDTIME_TABLE_SORT
130	select CLKEVT_I8253
131	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
132	select CLOCKSOURCE_WATCHDOG
133	select DCACHE_WORD_ACCESS
134	select DYNAMIC_SIGFRAME
135	select EDAC_ATOMIC_SCRUB
136	select EDAC_SUPPORT
137	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
138	select GENERIC_CLOCKEVENTS_MIN_ADJUST
139	select GENERIC_CMOS_UPDATE
140	select GENERIC_CPU_AUTOPROBE
141	select GENERIC_CPU_VULNERABILITIES
142	select GENERIC_EARLY_IOREMAP
143	select GENERIC_ENTRY
144	select GENERIC_IOMAP
145	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
146	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
147	select GENERIC_IRQ_MIGRATION		if SMP
148	select GENERIC_IRQ_PROBE
149	select GENERIC_IRQ_RESERVATION_MODE
150	select GENERIC_IRQ_SHOW
151	select GENERIC_PENDING_IRQ		if SMP
152	select GENERIC_PTDUMP
153	select GENERIC_SMP_IDLE_THREAD
154	select GENERIC_TIME_VSYSCALL
155	select GENERIC_GETTIMEOFDAY
156	select GENERIC_VDSO_TIME_NS
157	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
158	select HARDIRQS_SW_RESEND
159	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
160	select HAVE_ACPI_APEI			if ACPI
161	select HAVE_ACPI_APEI_NMI		if ACPI
162	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
163	select HAVE_ARCH_AUDITSYSCALL
164	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
165	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
166	select HAVE_ARCH_JUMP_LABEL
167	select HAVE_ARCH_JUMP_LABEL_RELATIVE
168	select HAVE_ARCH_KASAN			if X86_64
169	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
170	select HAVE_ARCH_KFENCE
171	select HAVE_ARCH_KGDB
172	select HAVE_ARCH_MMAP_RND_BITS		if MMU
173	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
174	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
175	select HAVE_ARCH_PREL32_RELOCATIONS
176	select HAVE_ARCH_SECCOMP_FILTER
177	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
178	select HAVE_ARCH_STACKLEAK
179	select HAVE_ARCH_TRACEHOOK
180	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
181	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
182	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
183	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
184	select HAVE_ARCH_VMAP_STACK		if X86_64
185	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
186	select HAVE_ARCH_WITHIN_STACK_FRAMES
187	select HAVE_ASM_MODVERSIONS
188	select HAVE_CMPXCHG_DOUBLE
189	select HAVE_CMPXCHG_LOCAL
190	select HAVE_CONTEXT_TRACKING_USER		if X86_64
191	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
192	select HAVE_C_RECORDMCOUNT
193	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
194	select HAVE_BUILDTIME_MCOUNT_SORT
195	select HAVE_DEBUG_KMEMLEAK
196	select HAVE_DMA_CONTIGUOUS
197	select HAVE_DYNAMIC_FTRACE
198	select HAVE_DYNAMIC_FTRACE_WITH_REGS
199	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
200	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
201	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
202	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
203	select HAVE_EBPF_JIT
204	select HAVE_EFFICIENT_UNALIGNED_ACCESS
205	select HAVE_EISA
206	select HAVE_EXIT_THREAD
207	select HAVE_FAST_GUP
208	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
209	select HAVE_FTRACE_MCOUNT_RECORD
210	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
211	select HAVE_FUNCTION_TRACER
212	select HAVE_GCC_PLUGINS
213	select HAVE_HW_BREAKPOINT
214	select HAVE_IOREMAP_PROT
215	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
216	select HAVE_IRQ_TIME_ACCOUNTING
217	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
218	select HAVE_KERNEL_BZIP2
219	select HAVE_KERNEL_GZIP
220	select HAVE_KERNEL_LZ4
221	select HAVE_KERNEL_LZMA
222	select HAVE_KERNEL_LZO
223	select HAVE_KERNEL_XZ
224	select HAVE_KERNEL_ZSTD
225	select HAVE_KPROBES
226	select HAVE_KPROBES_ON_FTRACE
227	select HAVE_FUNCTION_ERROR_INJECTION
228	select HAVE_KRETPROBES
229	select HAVE_RETHOOK
230	select HAVE_KVM
231	select HAVE_LIVEPATCH			if X86_64
232	select HAVE_MIXED_BREAKPOINTS_REGS
233	select HAVE_MOD_ARCH_SPECIFIC
234	select HAVE_MOVE_PMD
235	select HAVE_MOVE_PUD
236	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
237	select HAVE_NMI
238	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
239	select HAVE_OBJTOOL			if X86_64
240	select HAVE_OPTPROBES
241	select HAVE_PCSPKR_PLATFORM
242	select HAVE_PERF_EVENTS
243	select HAVE_PERF_EVENTS_NMI
244	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
245	select HAVE_PCI
246	select HAVE_PERF_REGS
247	select HAVE_PERF_USER_STACK_DUMP
248	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
249	select MMU_GATHER_MERGE_VMAS
250	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
251	select HAVE_REGS_AND_STACK_ACCESS_API
252	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
253	select HAVE_FUNCTION_ARG_ACCESS_API
254	select HAVE_SETUP_PER_CPU_AREA
255	select HAVE_SOFTIRQ_ON_OWN_STACK
256	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
257	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
258	select HAVE_STATIC_CALL
259	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
260	select HAVE_PREEMPT_DYNAMIC_CALL
261	select HAVE_RSEQ
262	select HAVE_RUST			if X86_64
263	select HAVE_SYSCALL_TRACEPOINTS
264	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
265	select HAVE_UNSTABLE_SCHED_CLOCK
266	select HAVE_USER_RETURN_NOTIFIER
267	select HAVE_GENERIC_VDSO
268	select HOTPLUG_SMT			if SMP
269	select IRQ_FORCED_THREADING
270	select NEED_PER_CPU_EMBED_FIRST_CHUNK
271	select NEED_PER_CPU_PAGE_FIRST_CHUNK
272	select NEED_SG_DMA_LENGTH
273	select PCI_DOMAINS			if PCI
274	select PCI_LOCKLESS_CONFIG		if PCI
275	select PERF_EVENTS
276	select RTC_LIB
277	select RTC_MC146818_LIB
278	select SPARSE_IRQ
279	select SRCU
280	select SYSCTL_EXCEPTION_TRACE
281	select THREAD_INFO_IN_TASK
282	select TRACE_IRQFLAGS_SUPPORT
283	select TRACE_IRQFLAGS_NMI_SUPPORT
284	select USER_STACKTRACE_SUPPORT
285	select HAVE_ARCH_KCSAN			if X86_64
286	select X86_FEATURE_NAMES		if PROC_FS
287	select PROC_PID_ARCH_STATUS		if PROC_FS
288	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
289	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
290	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
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_BUG
332	def_bool y
333	depends on BUG
334	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
335
336config GENERIC_BUG_RELATIVE_POINTERS
337	bool
338
339config ARCH_MAY_HAVE_PC_FDC
340	def_bool y
341	depends on ISA_DMA_API
342
343config GENERIC_CALIBRATE_DELAY
344	def_bool y
345
346config ARCH_HAS_CPU_RELAX
347	def_bool y
348
349config ARCH_HIBERNATION_POSSIBLE
350	def_bool y
351
352config ARCH_NR_GPIO
353	int
354	default 1024 if X86_64
355	default 512
356
357config ARCH_SUSPEND_POSSIBLE
358	def_bool y
359
360config AUDIT_ARCH
361	def_bool y if X86_64
362
363config KASAN_SHADOW_OFFSET
364	hex
365	depends on KASAN
366	default 0xdffffc0000000000
367
368config HAVE_INTEL_TXT
369	def_bool y
370	depends on INTEL_IOMMU && ACPI
371
372config X86_32_SMP
373	def_bool y
374	depends on X86_32 && SMP
375
376config X86_64_SMP
377	def_bool y
378	depends on X86_64 && SMP
379
380config ARCH_SUPPORTS_UPROBES
381	def_bool y
382
383config FIX_EARLYCON_MEM
384	def_bool y
385
386config DYNAMIC_PHYSICAL_MASK
387	bool
388
389config PGTABLE_LEVELS
390	int
391	default 5 if X86_5LEVEL
392	default 4 if X86_64
393	default 3 if X86_PAE
394	default 2
395
396config CC_HAS_SANE_STACKPROTECTOR
397	bool
398	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
399	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
400	help
401	  We have to make sure stack protector is unconditionally disabled if
402	  the compiler produces broken code or if it does not let us control
403	  the segment on 32-bit kernels.
404
405menu "Processor type and features"
406
407config SMP
408	bool "Symmetric multi-processing support"
409	help
410	  This enables support for systems with more than one CPU. If you have
411	  a system with only one CPU, say N. If you have a system with more
412	  than one CPU, say Y.
413
414	  If you say N here, the kernel will run on uni- and multiprocessor
415	  machines, but will use only one CPU of a multiprocessor machine. If
416	  you say Y here, the kernel will run on many, but not all,
417	  uniprocessor machines. On a uniprocessor machine, the kernel
418	  will run faster if you say N here.
419
420	  Note that if you say Y here and choose architecture "586" or
421	  "Pentium" under "Processor family", the kernel will not work on 486
422	  architectures. Similarly, multiprocessor kernels for the "PPro"
423	  architecture may not work on all Pentium based boards.
424
425	  People using multiprocessor machines who say Y here should also say
426	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
427	  Management" code will be disabled if you say Y here.
428
429	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
430	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
431	  <http://www.tldp.org/docs.html#howto>.
432
433	  If you don't know what to do here, say N.
434
435config X86_FEATURE_NAMES
436	bool "Processor feature human-readable names" if EMBEDDED
437	default y
438	help
439	  This option compiles in a table of x86 feature bits and corresponding
440	  names.  This is required to support /proc/cpuinfo and a few kernel
441	  messages.  You can disable this to save space, at the expense of
442	  making those few kernel messages show numeric feature bits instead.
443
444	  If in doubt, say Y.
445
446config X86_X2APIC
447	bool "Support x2apic"
448	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
449	help
450	  This enables x2apic support on CPUs that have this feature.
451
452	  This allows 32-bit apic IDs (so it can support very large systems),
453	  and accesses the local apic via MSRs not via mmio.
454
455	  Some Intel systems circa 2022 and later are locked into x2APIC mode
456	  and can not fall back to the legacy APIC modes if SGX or TDX are
457	  enabled in the BIOS.  They will be unable to boot without enabling
458	  this option.
459
460	  If you don't know what to do here, say N.
461
462config X86_MPPARSE
463	bool "Enable MPS table" if ACPI
464	default y
465	depends on X86_LOCAL_APIC
466	help
467	  For old smp systems that do not have proper acpi support. Newer systems
468	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
469
470config GOLDFISH
471	def_bool y
472	depends on X86_GOLDFISH
473
474config X86_CPU_RESCTRL
475	bool "x86 CPU resource control support"
476	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
477	select KERNFS
478	select PROC_CPU_RESCTRL		if PROC_FS
479	help
480	  Enable x86 CPU resource control support.
481
482	  Provide support for the allocation and monitoring of system resources
483	  usage by the CPU.
484
485	  Intel calls this Intel Resource Director Technology
486	  (Intel(R) RDT). More information about RDT can be found in the
487	  Intel x86 Architecture Software Developer Manual.
488
489	  AMD calls this AMD Platform Quality of Service (AMD QoS).
490	  More information about AMD QoS can be found in the AMD64 Technology
491	  Platform Quality of Service Extensions manual.
492
493	  Say N if unsure.
494
495if X86_32
496config X86_BIGSMP
497	bool "Support for big SMP systems with more than 8 CPUs"
498	depends on SMP
499	help
500	  This option is needed for the systems that have more than 8 CPUs.
501
502config X86_EXTENDED_PLATFORM
503	bool "Support for extended (non-PC) x86 platforms"
504	default y
505	help
506	  If you disable this option then the kernel will only support
507	  standard PC platforms. (which covers the vast majority of
508	  systems out there.)
509
510	  If you enable this option then you'll be able to select support
511	  for the following (non-PC) 32 bit x86 platforms:
512		Goldfish (Android emulator)
513		AMD Elan
514		RDC R-321x SoC
515		SGI 320/540 (Visual Workstation)
516		STA2X11-based (e.g. Northville)
517		Moorestown MID devices
518
519	  If you have one of these systems, or if you want to build a
520	  generic distribution kernel, say Y here - otherwise say N.
521endif # X86_32
522
523if X86_64
524config X86_EXTENDED_PLATFORM
525	bool "Support for extended (non-PC) x86 platforms"
526	default y
527	help
528	  If you disable this option then the kernel will only support
529	  standard PC platforms. (which covers the vast majority of
530	  systems out there.)
531
532	  If you enable this option then you'll be able to select support
533	  for the following (non-PC) 64 bit x86 platforms:
534		Numascale NumaChip
535		ScaleMP vSMP
536		SGI Ultraviolet
537
538	  If you have one of these systems, or if you want to build a
539	  generic distribution kernel, say Y here - otherwise say N.
540endif # X86_64
541# This is an alphabetically sorted list of 64 bit extended platforms
542# Please maintain the alphabetic order if and when there are additions
543config X86_NUMACHIP
544	bool "Numascale NumaChip"
545	depends on X86_64
546	depends on X86_EXTENDED_PLATFORM
547	depends on NUMA
548	depends on SMP
549	depends on X86_X2APIC
550	depends on PCI_MMCONFIG
551	help
552	  Adds support for Numascale NumaChip large-SMP systems. Needed to
553	  enable more than ~168 cores.
554	  If you don't have one of these, you should say N here.
555
556config X86_VSMP
557	bool "ScaleMP vSMP"
558	select HYPERVISOR_GUEST
559	select PARAVIRT
560	depends on X86_64 && PCI
561	depends on X86_EXTENDED_PLATFORM
562	depends on SMP
563	help
564	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
565	  supposed to run on these EM64T-based machines.  Only choose this option
566	  if you have one of these machines.
567
568config X86_UV
569	bool "SGI Ultraviolet"
570	depends on X86_64
571	depends on X86_EXTENDED_PLATFORM
572	depends on NUMA
573	depends on EFI
574	depends on KEXEC_CORE
575	depends on X86_X2APIC
576	depends on PCI
577	help
578	  This option is needed in order to support SGI Ultraviolet systems.
579	  If you don't have one of these, you should say N here.
580
581# Following is an alphabetically sorted list of 32 bit extended platforms
582# Please maintain the alphabetic order if and when there are additions
583
584config X86_GOLDFISH
585	bool "Goldfish (Virtual Platform)"
586	depends on X86_EXTENDED_PLATFORM
587	help
588	  Enable support for the Goldfish virtual platform used primarily
589	  for Android development. Unless you are building for the Android
590	  Goldfish emulator say N here.
591
592config X86_INTEL_CE
593	bool "CE4100 TV platform"
594	depends on PCI
595	depends on PCI_GODIRECT
596	depends on X86_IO_APIC
597	depends on X86_32
598	depends on X86_EXTENDED_PLATFORM
599	select X86_REBOOTFIXUPS
600	select OF
601	select OF_EARLY_FLATTREE
602	help
603	  Select for the Intel CE media processor (CE4100) SOC.
604	  This option compiles in support for the CE4100 SOC for settop
605	  boxes and media devices.
606
607config X86_INTEL_MID
608	bool "Intel MID platform support"
609	depends on X86_EXTENDED_PLATFORM
610	depends on X86_PLATFORM_DEVICES
611	depends on PCI
612	depends on X86_64 || (PCI_GOANY && X86_32)
613	depends on X86_IO_APIC
614	select I2C
615	select DW_APB_TIMER
616	select INTEL_SCU_PCI
617	help
618	  Select to build a kernel capable of supporting Intel MID (Mobile
619	  Internet Device) platform systems which do not have the PCI legacy
620	  interfaces. If you are building for a PC class system say N here.
621
622	  Intel MID platforms are based on an Intel processor and chipset which
623	  consume less power than most of the x86 derivatives.
624
625config X86_INTEL_QUARK
626	bool "Intel Quark platform support"
627	depends on X86_32
628	depends on X86_EXTENDED_PLATFORM
629	depends on X86_PLATFORM_DEVICES
630	depends on X86_TSC
631	depends on PCI
632	depends on PCI_GOANY
633	depends on X86_IO_APIC
634	select IOSF_MBI
635	select INTEL_IMR
636	select COMMON_CLK
637	help
638	  Select to include support for Quark X1000 SoC.
639	  Say Y here if you have a Quark based system such as the Arduino
640	  compatible Intel Galileo.
641
642config X86_INTEL_LPSS
643	bool "Intel Low Power Subsystem Support"
644	depends on X86 && ACPI && PCI
645	select COMMON_CLK
646	select PINCTRL
647	select IOSF_MBI
648	help
649	  Select to build support for Intel Low Power Subsystem such as
650	  found on Intel Lynxpoint PCH. Selecting this option enables
651	  things like clock tree (common clock framework) and pincontrol
652	  which are needed by the LPSS peripheral drivers.
653
654config X86_AMD_PLATFORM_DEVICE
655	bool "AMD ACPI2Platform devices support"
656	depends on ACPI
657	select COMMON_CLK
658	select PINCTRL
659	help
660	  Select to interpret AMD specific ACPI device to platform device
661	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
662	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
663	  implemented under PINCTRL subsystem.
664
665config IOSF_MBI
666	tristate "Intel SoC IOSF Sideband support for SoC platforms"
667	depends on PCI
668	help
669	  This option enables sideband register access support for Intel SoC
670	  platforms. On these platforms the IOSF sideband is used in lieu of
671	  MSR's for some register accesses, mostly but not limited to thermal
672	  and power. Drivers may query the availability of this device to
673	  determine if they need the sideband in order to work on these
674	  platforms. The sideband is available on the following SoC products.
675	  This list is not meant to be exclusive.
676	   - BayTrail
677	   - Braswell
678	   - Quark
679
680	  You should say Y if you are running a kernel on one of these SoC's.
681
682config IOSF_MBI_DEBUG
683	bool "Enable IOSF sideband access through debugfs"
684	depends on IOSF_MBI && DEBUG_FS
685	help
686	  Select this option to expose the IOSF sideband access registers (MCR,
687	  MDR, MCRX) through debugfs to write and read register information from
688	  different units on the SoC. This is most useful for obtaining device
689	  state information for debug and analysis. As this is a general access
690	  mechanism, users of this option would have specific knowledge of the
691	  device they want to access.
692
693	  If you don't require the option or are in doubt, say N.
694
695config X86_RDC321X
696	bool "RDC R-321x SoC"
697	depends on X86_32
698	depends on X86_EXTENDED_PLATFORM
699	select M486
700	select X86_REBOOTFIXUPS
701	help
702	  This option is needed for RDC R-321x system-on-chip, also known
703	  as R-8610-(G).
704	  If you don't have one of these chips, you should say N here.
705
706config X86_32_NON_STANDARD
707	bool "Support non-standard 32-bit SMP architectures"
708	depends on X86_32 && SMP
709	depends on X86_EXTENDED_PLATFORM
710	help
711	  This option compiles in the bigsmp and STA2X11 default
712	  subarchitectures.  It is intended for a generic binary
713	  kernel. If you select them all, kernel will probe it one by
714	  one and will fallback to default.
715
716# Alphabetically sorted list of Non standard 32 bit platforms
717
718config X86_SUPPORTS_MEMORY_FAILURE
719	def_bool y
720	# MCE code calls memory_failure():
721	depends on X86_MCE
722	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
723	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
724	depends on X86_64 || !SPARSEMEM
725	select ARCH_SUPPORTS_MEMORY_FAILURE
726
727config STA2X11
728	bool "STA2X11 Companion Chip Support"
729	depends on X86_32_NON_STANDARD && PCI
730	select SWIOTLB
731	select MFD_STA2X11
732	select GPIOLIB
733	help
734	  This adds support for boards based on the STA2X11 IO-Hub,
735	  a.k.a. "ConneXt". The chip is used in place of the standard
736	  PC chipset, so all "standard" peripherals are missing. If this
737	  option is selected the kernel will still be able to boot on
738	  standard PC machines.
739
740config X86_32_IRIS
741	tristate "Eurobraille/Iris poweroff module"
742	depends on X86_32
743	help
744	  The Iris machines from EuroBraille do not have APM or ACPI support
745	  to shut themselves down properly.  A special I/O sequence is
746	  needed to do so, which is what this module does at
747	  kernel shutdown.
748
749	  This is only for Iris machines from EuroBraille.
750
751	  If unused, say N.
752
753config SCHED_OMIT_FRAME_POINTER
754	def_bool y
755	prompt "Single-depth WCHAN output"
756	depends on X86
757	help
758	  Calculate simpler /proc/<PID>/wchan values. If this option
759	  is disabled then wchan values will recurse back to the
760	  caller function. This provides more accurate wchan values,
761	  at the expense of slightly more scheduling overhead.
762
763	  If in doubt, say "Y".
764
765menuconfig HYPERVISOR_GUEST
766	bool "Linux guest support"
767	help
768	  Say Y here to enable options for running Linux under various hyper-
769	  visors. This option enables basic hypervisor detection and platform
770	  setup.
771
772	  If you say N, all options in this submenu will be skipped and
773	  disabled, and Linux guest support won't be built in.
774
775if HYPERVISOR_GUEST
776
777config PARAVIRT
778	bool "Enable paravirtualization code"
779	depends on HAVE_STATIC_CALL
780	help
781	  This changes the kernel so it can modify itself when it is run
782	  under a hypervisor, potentially improving performance significantly
783	  over full virtualization.  However, when run without a hypervisor
784	  the kernel is theoretically slower and slightly larger.
785
786config PARAVIRT_XXL
787	bool
788
789config PARAVIRT_DEBUG
790	bool "paravirt-ops debugging"
791	depends on PARAVIRT && DEBUG_KERNEL
792	help
793	  Enable to debug paravirt_ops internals.  Specifically, BUG if
794	  a paravirt_op is missing when it is called.
795
796config PARAVIRT_SPINLOCKS
797	bool "Paravirtualization layer for spinlocks"
798	depends on PARAVIRT && SMP
799	help
800	  Paravirtualized spinlocks allow a pvops backend to replace the
801	  spinlock implementation with something virtualization-friendly
802	  (for example, block the virtual CPU rather than spinning).
803
804	  It has a minimal impact on native kernels and gives a nice performance
805	  benefit on paravirtualized KVM / Xen kernels.
806
807	  If you are unsure how to answer this question, answer Y.
808
809config X86_HV_CALLBACK_VECTOR
810	def_bool n
811
812source "arch/x86/xen/Kconfig"
813
814config KVM_GUEST
815	bool "KVM Guest support (including kvmclock)"
816	depends on PARAVIRT
817	select PARAVIRT_CLOCK
818	select ARCH_CPUIDLE_HALTPOLL
819	select X86_HV_CALLBACK_VECTOR
820	default y
821	help
822	  This option enables various optimizations for running under the KVM
823	  hypervisor. It includes a paravirtualized clock, so that instead
824	  of relying on a PIT (or probably other) emulation by the
825	  underlying device model, the host provides the guest with
826	  timing infrastructure such as time of day, and system time
827
828config ARCH_CPUIDLE_HALTPOLL
829	def_bool n
830	prompt "Disable host haltpoll when loading haltpoll driver"
831	help
832	  If virtualized under KVM, disable host haltpoll.
833
834config PVH
835	bool "Support for running PVH guests"
836	help
837	  This option enables the PVH entry point for guest virtual machines
838	  as specified in the x86/HVM direct boot ABI.
839
840config PARAVIRT_TIME_ACCOUNTING
841	bool "Paravirtual steal time accounting"
842	depends on PARAVIRT
843	help
844	  Select this option to enable fine granularity task steal time
845	  accounting. Time spent executing other tasks in parallel with
846	  the current vCPU is discounted from the vCPU power. To account for
847	  that, there can be a small performance impact.
848
849	  If in doubt, say N here.
850
851config PARAVIRT_CLOCK
852	bool
853
854config JAILHOUSE_GUEST
855	bool "Jailhouse non-root cell support"
856	depends on X86_64 && PCI
857	select X86_PM_TIMER
858	help
859	  This option allows to run Linux as guest in a Jailhouse non-root
860	  cell. You can leave this option disabled if you only want to start
861	  Jailhouse and run Linux afterwards in the root cell.
862
863config ACRN_GUEST
864	bool "ACRN Guest support"
865	depends on X86_64
866	select X86_HV_CALLBACK_VECTOR
867	help
868	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
869	  a flexible, lightweight reference open-source hypervisor, built with
870	  real-time and safety-criticality in mind. It is built for embedded
871	  IOT with small footprint and real-time features. More details can be
872	  found in https://projectacrn.org/.
873
874config INTEL_TDX_GUEST
875	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
876	depends on X86_64 && CPU_SUP_INTEL
877	depends on X86_X2APIC
878	select ARCH_HAS_CC_PLATFORM
879	select X86_MEM_ENCRYPT
880	select X86_MCE
881	help
882	  Support running as a guest under Intel TDX.  Without this support,
883	  the guest kernel can not boot or run under TDX.
884	  TDX includes memory encryption and integrity capabilities
885	  which protect the confidentiality and integrity of guest
886	  memory contents and CPU state. TDX guests are protected from
887	  some attacks from the VMM.
888
889endif # HYPERVISOR_GUEST
890
891source "arch/x86/Kconfig.cpu"
892
893config HPET_TIMER
894	def_bool X86_64
895	prompt "HPET Timer Support" if X86_32
896	help
897	  Use the IA-PC HPET (High Precision Event Timer) to manage
898	  time in preference to the PIT and RTC, if a HPET is
899	  present.
900	  HPET is the next generation timer replacing legacy 8254s.
901	  The HPET provides a stable time base on SMP
902	  systems, unlike the TSC, but it is more expensive to access,
903	  as it is off-chip.  The interface used is documented
904	  in the HPET spec, revision 1.
905
906	  You can safely choose Y here.  However, HPET will only be
907	  activated if the platform and the BIOS support this feature.
908	  Otherwise the 8254 will be used for timing services.
909
910	  Choose N to continue using the legacy 8254 timer.
911
912config HPET_EMULATE_RTC
913	def_bool y
914	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
915
916# Mark as expert because too many people got it wrong.
917# The code disables itself when not needed.
918config DMI
919	default y
920	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
921	bool "Enable DMI scanning" if EXPERT
922	help
923	  Enabled scanning of DMI to identify machine quirks. Say Y
924	  here unless you have verified that your setup is not
925	  affected by entries in the DMI blacklist. Required by PNP
926	  BIOS code.
927
928config GART_IOMMU
929	bool "Old AMD GART IOMMU support"
930	select DMA_OPS
931	select IOMMU_HELPER
932	select SWIOTLB
933	depends on X86_64 && PCI && AMD_NB
934	help
935	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
936	  GART based hardware IOMMUs.
937
938	  The GART supports full DMA access for devices with 32-bit access
939	  limitations, on systems with more than 3 GB. This is usually needed
940	  for USB, sound, many IDE/SATA chipsets and some other devices.
941
942	  Newer systems typically have a modern AMD IOMMU, supported via
943	  the CONFIG_AMD_IOMMU=y config option.
944
945	  In normal configurations this driver is only active when needed:
946	  there's more than 3 GB of memory and the system contains a
947	  32-bit limited device.
948
949	  If unsure, say Y.
950
951config BOOT_VESA_SUPPORT
952	bool
953	help
954	  If true, at least one selected framebuffer driver can take advantage
955	  of VESA video modes set at an early boot stage via the vga= parameter.
956
957config MAXSMP
958	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
959	depends on X86_64 && SMP && DEBUG_KERNEL
960	select CPUMASK_OFFSTACK
961	help
962	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
963	  If unsure, say N.
964
965#
966# The maximum number of CPUs supported:
967#
968# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
969# and which can be configured interactively in the
970# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
971#
972# The ranges are different on 32-bit and 64-bit kernels, depending on
973# hardware capabilities and scalability features of the kernel.
974#
975# ( If MAXSMP is enabled we just use the highest possible value and disable
976#   interactive configuration. )
977#
978
979config NR_CPUS_RANGE_BEGIN
980	int
981	default NR_CPUS_RANGE_END if MAXSMP
982	default    1 if !SMP
983	default    2
984
985config NR_CPUS_RANGE_END
986	int
987	depends on X86_32
988	default   64 if  SMP &&  X86_BIGSMP
989	default    8 if  SMP && !X86_BIGSMP
990	default    1 if !SMP
991
992config NR_CPUS_RANGE_END
993	int
994	depends on X86_64
995	default 8192 if  SMP && CPUMASK_OFFSTACK
996	default  512 if  SMP && !CPUMASK_OFFSTACK
997	default    1 if !SMP
998
999config NR_CPUS_DEFAULT
1000	int
1001	depends on X86_32
1002	default   32 if  X86_BIGSMP
1003	default    8 if  SMP
1004	default    1 if !SMP
1005
1006config NR_CPUS_DEFAULT
1007	int
1008	depends on X86_64
1009	default 8192 if  MAXSMP
1010	default   64 if  SMP
1011	default    1 if !SMP
1012
1013config NR_CPUS
1014	int "Maximum number of CPUs" if SMP && !MAXSMP
1015	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1016	default NR_CPUS_DEFAULT
1017	help
1018	  This allows you to specify the maximum number of CPUs which this
1019	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1020	  supported value is 8192, otherwise the maximum value is 512.  The
1021	  minimum value which makes sense is 2.
1022
1023	  This is purely to save memory: each supported CPU adds about 8KB
1024	  to the kernel image.
1025
1026config SCHED_CLUSTER
1027	bool "Cluster scheduler support"
1028	depends on SMP
1029	default y
1030	help
1031	  Cluster scheduler support improves the CPU scheduler's decision
1032	  making when dealing with machines that have clusters of CPUs.
1033	  Cluster usually means a couple of CPUs which are placed closely
1034	  by sharing mid-level caches, last-level cache tags or internal
1035	  busses.
1036
1037config SCHED_SMT
1038	def_bool y if SMP
1039
1040config SCHED_MC
1041	def_bool y
1042	prompt "Multi-core scheduler support"
1043	depends on SMP
1044	help
1045	  Multi-core scheduler support improves the CPU scheduler's decision
1046	  making when dealing with multi-core CPU chips at a cost of slightly
1047	  increased overhead in some places. If unsure say N here.
1048
1049config SCHED_MC_PRIO
1050	bool "CPU core priorities scheduler support"
1051	depends on SCHED_MC && CPU_SUP_INTEL
1052	select X86_INTEL_PSTATE
1053	select CPU_FREQ
1054	default y
1055	help
1056	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1057	  core ordering determined at manufacturing time, which allows
1058	  certain cores to reach higher turbo frequencies (when running
1059	  single threaded workloads) than others.
1060
1061	  Enabling this kernel feature teaches the scheduler about
1062	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1063	  scheduler's CPU selection logic accordingly, so that higher
1064	  overall system performance can be achieved.
1065
1066	  This feature will have no effect on CPUs without this feature.
1067
1068	  If unsure say Y here.
1069
1070config UP_LATE_INIT
1071	def_bool y
1072	depends on !SMP && X86_LOCAL_APIC
1073
1074config X86_UP_APIC
1075	bool "Local APIC support on uniprocessors" if !PCI_MSI
1076	default PCI_MSI
1077	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1078	help
1079	  A local APIC (Advanced Programmable Interrupt Controller) is an
1080	  integrated interrupt controller in the CPU. If you have a single-CPU
1081	  system which has a processor with a local APIC, you can say Y here to
1082	  enable and use it. If you say Y here even though your machine doesn't
1083	  have a local APIC, then the kernel will still run with no slowdown at
1084	  all. The local APIC supports CPU-generated self-interrupts (timer,
1085	  performance counters), and the NMI watchdog which detects hard
1086	  lockups.
1087
1088config X86_UP_IOAPIC
1089	bool "IO-APIC support on uniprocessors"
1090	depends on X86_UP_APIC
1091	help
1092	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1093	  SMP-capable replacement for PC-style interrupt controllers. Most
1094	  SMP systems and many recent uniprocessor systems have one.
1095
1096	  If you have a single-CPU system with an IO-APIC, you can say Y here
1097	  to use it. If you say Y here even though your machine doesn't have
1098	  an IO-APIC, then the kernel will still run with no slowdown at all.
1099
1100config X86_LOCAL_APIC
1101	def_bool y
1102	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1103	select IRQ_DOMAIN_HIERARCHY
1104	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1105
1106config X86_IO_APIC
1107	def_bool y
1108	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1109
1110config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1111	bool "Reroute for broken boot IRQs"
1112	depends on X86_IO_APIC
1113	help
1114	  This option enables a workaround that fixes a source of
1115	  spurious interrupts. This is recommended when threaded
1116	  interrupt handling is used on systems where the generation of
1117	  superfluous "boot interrupts" cannot be disabled.
1118
1119	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1120	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1121	  kernel does during interrupt handling). On chipsets where this
1122	  boot IRQ generation cannot be disabled, this workaround keeps
1123	  the original IRQ line masked so that only the equivalent "boot
1124	  IRQ" is delivered to the CPUs. The workaround also tells the
1125	  kernel to set up the IRQ handler on the boot IRQ line. In this
1126	  way only one interrupt is delivered to the kernel. Otherwise
1127	  the spurious second interrupt may cause the kernel to bring
1128	  down (vital) interrupt lines.
1129
1130	  Only affects "broken" chipsets. Interrupt sharing may be
1131	  increased on these systems.
1132
1133config X86_MCE
1134	bool "Machine Check / overheating reporting"
1135	select GENERIC_ALLOCATOR
1136	default y
1137	help
1138	  Machine Check support allows the processor to notify the
1139	  kernel if it detects a problem (e.g. overheating, data corruption).
1140	  The action the kernel takes depends on the severity of the problem,
1141	  ranging from warning messages to halting the machine.
1142
1143config X86_MCELOG_LEGACY
1144	bool "Support for deprecated /dev/mcelog character device"
1145	depends on X86_MCE
1146	help
1147	  Enable support for /dev/mcelog which is needed by the old mcelog
1148	  userspace logging daemon. Consider switching to the new generation
1149	  rasdaemon solution.
1150
1151config X86_MCE_INTEL
1152	def_bool y
1153	prompt "Intel MCE features"
1154	depends on X86_MCE && X86_LOCAL_APIC
1155	help
1156	  Additional support for intel specific MCE features such as
1157	  the thermal monitor.
1158
1159config X86_MCE_AMD
1160	def_bool y
1161	prompt "AMD MCE features"
1162	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1163	help
1164	  Additional support for AMD specific MCE features such as
1165	  the DRAM Error Threshold.
1166
1167config X86_ANCIENT_MCE
1168	bool "Support for old Pentium 5 / WinChip machine checks"
1169	depends on X86_32 && X86_MCE
1170	help
1171	  Include support for machine check handling on old Pentium 5 or WinChip
1172	  systems. These typically need to be enabled explicitly on the command
1173	  line.
1174
1175config X86_MCE_THRESHOLD
1176	depends on X86_MCE_AMD || X86_MCE_INTEL
1177	def_bool y
1178
1179config X86_MCE_INJECT
1180	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1181	tristate "Machine check injector support"
1182	help
1183	  Provide support for injecting machine checks for testing purposes.
1184	  If you don't know what a machine check is and you don't do kernel
1185	  QA it is safe to say n.
1186
1187source "arch/x86/events/Kconfig"
1188
1189config X86_LEGACY_VM86
1190	bool "Legacy VM86 support"
1191	depends on X86_32
1192	help
1193	  This option allows user programs to put the CPU into V8086
1194	  mode, which is an 80286-era approximation of 16-bit real mode.
1195
1196	  Some very old versions of X and/or vbetool require this option
1197	  for user mode setting.  Similarly, DOSEMU will use it if
1198	  available to accelerate real mode DOS programs.  However, any
1199	  recent version of DOSEMU, X, or vbetool should be fully
1200	  functional even without kernel VM86 support, as they will all
1201	  fall back to software emulation. Nevertheless, if you are using
1202	  a 16-bit DOS program where 16-bit performance matters, vm86
1203	  mode might be faster than emulation and you might want to
1204	  enable this option.
1205
1206	  Note that any app that works on a 64-bit kernel is unlikely to
1207	  need this option, as 64-bit kernels don't, and can't, support
1208	  V8086 mode. This option is also unrelated to 16-bit protected
1209	  mode and is not needed to run most 16-bit programs under Wine.
1210
1211	  Enabling this option increases the complexity of the kernel
1212	  and slows down exception handling a tiny bit.
1213
1214	  If unsure, say N here.
1215
1216config VM86
1217	bool
1218	default X86_LEGACY_VM86
1219
1220config X86_16BIT
1221	bool "Enable support for 16-bit segments" if EXPERT
1222	default y
1223	depends on MODIFY_LDT_SYSCALL
1224	help
1225	  This option is required by programs like Wine to run 16-bit
1226	  protected mode legacy code on x86 processors.  Disabling
1227	  this option saves about 300 bytes on i386, or around 6K text
1228	  plus 16K runtime memory on x86-64,
1229
1230config X86_ESPFIX32
1231	def_bool y
1232	depends on X86_16BIT && X86_32
1233
1234config X86_ESPFIX64
1235	def_bool y
1236	depends on X86_16BIT && X86_64
1237
1238config X86_VSYSCALL_EMULATION
1239	bool "Enable vsyscall emulation" if EXPERT
1240	default y
1241	depends on X86_64
1242	help
1243	  This enables emulation of the legacy vsyscall page.  Disabling
1244	  it is roughly equivalent to booting with vsyscall=none, except
1245	  that it will also disable the helpful warning if a program
1246	  tries to use a vsyscall.  With this option set to N, offending
1247	  programs will just segfault, citing addresses of the form
1248	  0xffffffffff600?00.
1249
1250	  This option is required by many programs built before 2013, and
1251	  care should be used even with newer programs if set to N.
1252
1253	  Disabling this option saves about 7K of kernel size and
1254	  possibly 4K of additional runtime pagetable memory.
1255
1256config X86_IOPL_IOPERM
1257	bool "IOPERM and IOPL Emulation"
1258	default y
1259	help
1260	  This enables the ioperm() and iopl() syscalls which are necessary
1261	  for legacy applications.
1262
1263	  Legacy IOPL support is an overbroad mechanism which allows user
1264	  space aside of accessing all 65536 I/O ports also to disable
1265	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1266	  capabilities and permission from potentially active security
1267	  modules.
1268
1269	  The emulation restricts the functionality of the syscall to
1270	  only allowing the full range I/O port access, but prevents the
1271	  ability to disable interrupts from user space which would be
1272	  granted if the hardware IOPL mechanism would be used.
1273
1274config TOSHIBA
1275	tristate "Toshiba Laptop support"
1276	depends on X86_32
1277	help
1278	  This adds a driver to safely access the System Management Mode of
1279	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1280	  not work on models with a Phoenix BIOS. The System Management Mode
1281	  is used to set the BIOS and power saving options on Toshiba portables.
1282
1283	  For information on utilities to make use of this driver see the
1284	  Toshiba Linux utilities web site at:
1285	  <http://www.buzzard.org.uk/toshiba/>.
1286
1287	  Say Y if you intend to run this kernel on a Toshiba portable.
1288	  Say N otherwise.
1289
1290config X86_REBOOTFIXUPS
1291	bool "Enable X86 board specific fixups for reboot"
1292	depends on X86_32
1293	help
1294	  This enables chipset and/or board specific fixups to be done
1295	  in order to get reboot to work correctly. This is only needed on
1296	  some combinations of hardware and BIOS. The symptom, for which
1297	  this config is intended, is when reboot ends with a stalled/hung
1298	  system.
1299
1300	  Currently, the only fixup is for the Geode machines using
1301	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1302
1303	  Say Y if you want to enable the fixup. Currently, it's safe to
1304	  enable this option even if you don't need it.
1305	  Say N otherwise.
1306
1307config MICROCODE
1308	bool "CPU microcode loading support"
1309	default y
1310	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1311	help
1312	  If you say Y here, you will be able to update the microcode on
1313	  Intel and AMD processors. The Intel support is for the IA32 family,
1314	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1315	  AMD support is for families 0x10 and later. You will obviously need
1316	  the actual microcode binary data itself which is not shipped with
1317	  the Linux kernel.
1318
1319	  The preferred method to load microcode from a detached initrd is described
1320	  in Documentation/x86/microcode.rst. For that you need to enable
1321	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1322	  initrd for microcode blobs.
1323
1324	  In addition, you can build the microcode into the kernel. For that you
1325	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1326	  config option.
1327
1328config MICROCODE_INTEL
1329	bool "Intel microcode loading support"
1330	depends on CPU_SUP_INTEL && MICROCODE
1331	default MICROCODE
1332	help
1333	  This options enables microcode patch loading support for Intel
1334	  processors.
1335
1336	  For the current Intel microcode data package go to
1337	  <https://downloadcenter.intel.com> and search for
1338	  'Linux Processor Microcode Data File'.
1339
1340config MICROCODE_AMD
1341	bool "AMD microcode loading support"
1342	depends on CPU_SUP_AMD && MICROCODE
1343	help
1344	  If you select this option, microcode patch loading support for AMD
1345	  processors will be enabled.
1346
1347config MICROCODE_LATE_LOADING
1348	bool "Late microcode loading (DANGEROUS)"
1349	default n
1350	depends on MICROCODE
1351	help
1352	  Loading microcode late, when the system is up and executing instructions
1353	  is a tricky business and should be avoided if possible. Just the sequence
1354	  of synchronizing all cores and SMT threads is one fragile dance which does
1355	  not guarantee that cores might not softlock after the loading. Therefore,
1356	  use this at your own risk. Late loading taints the kernel too.
1357
1358config X86_MSR
1359	tristate "/dev/cpu/*/msr - Model-specific register support"
1360	help
1361	  This device gives privileged processes access to the x86
1362	  Model-Specific Registers (MSRs).  It is a character device with
1363	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1364	  MSR accesses are directed to a specific CPU on multi-processor
1365	  systems.
1366
1367config X86_CPUID
1368	tristate "/dev/cpu/*/cpuid - CPU information support"
1369	help
1370	  This device gives processes access to the x86 CPUID instruction to
1371	  be executed on a specific processor.  It is a character device
1372	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1373	  /dev/cpu/31/cpuid.
1374
1375choice
1376	prompt "High Memory Support"
1377	default HIGHMEM4G
1378	depends on X86_32
1379
1380config NOHIGHMEM
1381	bool "off"
1382	help
1383	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1384	  However, the address space of 32-bit x86 processors is only 4
1385	  Gigabytes large. That means that, if you have a large amount of
1386	  physical memory, not all of it can be "permanently mapped" by the
1387	  kernel. The physical memory that's not permanently mapped is called
1388	  "high memory".
1389
1390	  If you are compiling a kernel which will never run on a machine with
1391	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1392	  choice and suitable for most users). This will result in a "3GB/1GB"
1393	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1394	  space and the remaining part of the 4GB virtual memory space is used
1395	  by the kernel to permanently map as much physical memory as
1396	  possible.
1397
1398	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1399	  answer "4GB" here.
1400
1401	  If more than 4 Gigabytes is used then answer "64GB" here. This
1402	  selection turns Intel PAE (Physical Address Extension) mode on.
1403	  PAE implements 3-level paging on IA32 processors. PAE is fully
1404	  supported by Linux, PAE mode is implemented on all recent Intel
1405	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1406	  then the kernel will not boot on CPUs that don't support PAE!
1407
1408	  The actual amount of total physical memory will either be
1409	  auto detected or can be forced by using a kernel command line option
1410	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1411	  your boot loader (lilo or loadlin) about how to pass options to the
1412	  kernel at boot time.)
1413
1414	  If unsure, say "off".
1415
1416config HIGHMEM4G
1417	bool "4GB"
1418	help
1419	  Select this if you have a 32-bit processor and between 1 and 4
1420	  gigabytes of physical RAM.
1421
1422config HIGHMEM64G
1423	bool "64GB"
1424	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1425	select X86_PAE
1426	help
1427	  Select this if you have a 32-bit processor and more than 4
1428	  gigabytes of physical RAM.
1429
1430endchoice
1431
1432choice
1433	prompt "Memory split" if EXPERT
1434	default VMSPLIT_3G
1435	depends on X86_32
1436	help
1437	  Select the desired split between kernel and user memory.
1438
1439	  If the address range available to the kernel is less than the
1440	  physical memory installed, the remaining memory will be available
1441	  as "high memory". Accessing high memory is a little more costly
1442	  than low memory, as it needs to be mapped into the kernel first.
1443	  Note that increasing the kernel address space limits the range
1444	  available to user programs, making the address space there
1445	  tighter.  Selecting anything other than the default 3G/1G split
1446	  will also likely make your kernel incompatible with binary-only
1447	  kernel modules.
1448
1449	  If you are not absolutely sure what you are doing, leave this
1450	  option alone!
1451
1452	config VMSPLIT_3G
1453		bool "3G/1G user/kernel split"
1454	config VMSPLIT_3G_OPT
1455		depends on !X86_PAE
1456		bool "3G/1G user/kernel split (for full 1G low memory)"
1457	config VMSPLIT_2G
1458		bool "2G/2G user/kernel split"
1459	config VMSPLIT_2G_OPT
1460		depends on !X86_PAE
1461		bool "2G/2G user/kernel split (for full 2G low memory)"
1462	config VMSPLIT_1G
1463		bool "1G/3G user/kernel split"
1464endchoice
1465
1466config PAGE_OFFSET
1467	hex
1468	default 0xB0000000 if VMSPLIT_3G_OPT
1469	default 0x80000000 if VMSPLIT_2G
1470	default 0x78000000 if VMSPLIT_2G_OPT
1471	default 0x40000000 if VMSPLIT_1G
1472	default 0xC0000000
1473	depends on X86_32
1474
1475config HIGHMEM
1476	def_bool y
1477	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1478
1479config X86_PAE
1480	bool "PAE (Physical Address Extension) Support"
1481	depends on X86_32 && !HIGHMEM4G
1482	select PHYS_ADDR_T_64BIT
1483	select SWIOTLB
1484	help
1485	  PAE is required for NX support, and furthermore enables
1486	  larger swapspace support for non-overcommit purposes. It
1487	  has the cost of more pagetable lookup overhead, and also
1488	  consumes more pagetable space per process.
1489
1490config X86_5LEVEL
1491	bool "Enable 5-level page tables support"
1492	default y
1493	select DYNAMIC_MEMORY_LAYOUT
1494	select SPARSEMEM_VMEMMAP
1495	depends on X86_64
1496	help
1497	  5-level paging enables access to larger address space:
1498	  upto 128 PiB of virtual address space and 4 PiB of
1499	  physical address space.
1500
1501	  It will be supported by future Intel CPUs.
1502
1503	  A kernel with the option enabled can be booted on machines that
1504	  support 4- or 5-level paging.
1505
1506	  See Documentation/x86/x86_64/5level-paging.rst for more
1507	  information.
1508
1509	  Say N if unsure.
1510
1511config X86_DIRECT_GBPAGES
1512	def_bool y
1513	depends on X86_64
1514	help
1515	  Certain kernel features effectively disable kernel
1516	  linear 1 GB mappings (even if the CPU otherwise
1517	  supports them), so don't confuse the user by printing
1518	  that we have them enabled.
1519
1520config X86_CPA_STATISTICS
1521	bool "Enable statistic for Change Page Attribute"
1522	depends on DEBUG_FS
1523	help
1524	  Expose statistics about the Change Page Attribute mechanism, which
1525	  helps to determine the effectiveness of preserving large and huge
1526	  page mappings when mapping protections are changed.
1527
1528config X86_MEM_ENCRYPT
1529	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1530	select DYNAMIC_PHYSICAL_MASK
1531	def_bool n
1532
1533config AMD_MEM_ENCRYPT
1534	bool "AMD Secure Memory Encryption (SME) support"
1535	depends on X86_64 && CPU_SUP_AMD
1536	select DMA_COHERENT_POOL
1537	select ARCH_USE_MEMREMAP_PROT
1538	select INSTRUCTION_DECODER
1539	select ARCH_HAS_CC_PLATFORM
1540	select X86_MEM_ENCRYPT
1541	help
1542	  Say yes to enable support for the encryption of system memory.
1543	  This requires an AMD processor that supports Secure Memory
1544	  Encryption (SME).
1545
1546config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1547	bool "Activate AMD Secure Memory Encryption (SME) by default"
1548	depends on AMD_MEM_ENCRYPT
1549	help
1550	  Say yes to have system memory encrypted by default if running on
1551	  an AMD processor that supports Secure Memory Encryption (SME).
1552
1553	  If set to Y, then the encryption of system memory can be
1554	  deactivated with the mem_encrypt=off command line option.
1555
1556	  If set to N, then the encryption of system memory can be
1557	  activated with the mem_encrypt=on command line option.
1558
1559# Common NUMA Features
1560config NUMA
1561	bool "NUMA Memory Allocation and Scheduler Support"
1562	depends on SMP
1563	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1564	default y if X86_BIGSMP
1565	select USE_PERCPU_NUMA_NODE_ID
1566	help
1567	  Enable NUMA (Non-Uniform Memory Access) support.
1568
1569	  The kernel will try to allocate memory used by a CPU on the
1570	  local memory controller of the CPU and add some more
1571	  NUMA awareness to the kernel.
1572
1573	  For 64-bit this is recommended if the system is Intel Core i7
1574	  (or later), AMD Opteron, or EM64T NUMA.
1575
1576	  For 32-bit this is only needed if you boot a 32-bit
1577	  kernel on a 64-bit NUMA platform.
1578
1579	  Otherwise, you should say N.
1580
1581config AMD_NUMA
1582	def_bool y
1583	prompt "Old style AMD Opteron NUMA detection"
1584	depends on X86_64 && NUMA && PCI
1585	help
1586	  Enable AMD NUMA node topology detection.  You should say Y here if
1587	  you have a multi processor AMD system. This uses an old method to
1588	  read the NUMA configuration directly from the builtin Northbridge
1589	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1590	  which also takes priority if both are compiled in.
1591
1592config X86_64_ACPI_NUMA
1593	def_bool y
1594	prompt "ACPI NUMA detection"
1595	depends on X86_64 && NUMA && ACPI && PCI
1596	select ACPI_NUMA
1597	help
1598	  Enable ACPI SRAT based node topology detection.
1599
1600config NUMA_EMU
1601	bool "NUMA emulation"
1602	depends on NUMA
1603	help
1604	  Enable NUMA emulation. A flat machine will be split
1605	  into virtual nodes when booted with "numa=fake=N", where N is the
1606	  number of nodes. This is only useful for debugging.
1607
1608config NODES_SHIFT
1609	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1610	range 1 10
1611	default "10" if MAXSMP
1612	default "6" if X86_64
1613	default "3"
1614	depends on NUMA
1615	help
1616	  Specify the maximum number of NUMA Nodes available on the target
1617	  system.  Increases memory reserved to accommodate various tables.
1618
1619config ARCH_FLATMEM_ENABLE
1620	def_bool y
1621	depends on X86_32 && !NUMA
1622
1623config ARCH_SPARSEMEM_ENABLE
1624	def_bool y
1625	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1626	select SPARSEMEM_STATIC if X86_32
1627	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1628
1629config ARCH_SPARSEMEM_DEFAULT
1630	def_bool X86_64 || (NUMA && X86_32)
1631
1632config ARCH_SELECT_MEMORY_MODEL
1633	def_bool y
1634	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1635
1636config ARCH_MEMORY_PROBE
1637	bool "Enable sysfs memory/probe interface"
1638	depends on MEMORY_HOTPLUG
1639	help
1640	  This option enables a sysfs memory/probe interface for testing.
1641	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1642	  If you are unsure how to answer this question, answer N.
1643
1644config ARCH_PROC_KCORE_TEXT
1645	def_bool y
1646	depends on X86_64 && PROC_KCORE
1647
1648config ILLEGAL_POINTER_VALUE
1649	hex
1650	default 0 if X86_32
1651	default 0xdead000000000000 if X86_64
1652
1653config X86_PMEM_LEGACY_DEVICE
1654	bool
1655
1656config X86_PMEM_LEGACY
1657	tristate "Support non-standard NVDIMMs and ADR protected memory"
1658	depends on PHYS_ADDR_T_64BIT
1659	depends on BLK_DEV
1660	select X86_PMEM_LEGACY_DEVICE
1661	select NUMA_KEEP_MEMINFO if NUMA
1662	select LIBNVDIMM
1663	help
1664	  Treat memory marked using the non-standard e820 type of 12 as used
1665	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1666	  The kernel will offer these regions to the 'pmem' driver so
1667	  they can be used for persistent storage.
1668
1669	  Say Y if unsure.
1670
1671config HIGHPTE
1672	bool "Allocate 3rd-level pagetables from highmem"
1673	depends on HIGHMEM
1674	help
1675	  The VM uses one page table entry for each page of physical memory.
1676	  For systems with a lot of RAM, this can be wasteful of precious
1677	  low memory.  Setting this option will put user-space page table
1678	  entries in high memory.
1679
1680config X86_CHECK_BIOS_CORRUPTION
1681	bool "Check for low memory corruption"
1682	help
1683	  Periodically check for memory corruption in low memory, which
1684	  is suspected to be caused by BIOS.  Even when enabled in the
1685	  configuration, it is disabled at runtime.  Enable it by
1686	  setting "memory_corruption_check=1" on the kernel command
1687	  line.  By default it scans the low 64k of memory every 60
1688	  seconds; see the memory_corruption_check_size and
1689	  memory_corruption_check_period parameters in
1690	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1691
1692	  When enabled with the default parameters, this option has
1693	  almost no overhead, as it reserves a relatively small amount
1694	  of memory and scans it infrequently.  It both detects corruption
1695	  and prevents it from affecting the running system.
1696
1697	  It is, however, intended as a diagnostic tool; if repeatable
1698	  BIOS-originated corruption always affects the same memory,
1699	  you can use memmap= to prevent the kernel from using that
1700	  memory.
1701
1702config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1703	bool "Set the default setting of memory_corruption_check"
1704	depends on X86_CHECK_BIOS_CORRUPTION
1705	default y
1706	help
1707	  Set whether the default state of memory_corruption_check is
1708	  on or off.
1709
1710config MATH_EMULATION
1711	bool
1712	depends on MODIFY_LDT_SYSCALL
1713	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1714	help
1715	  Linux can emulate a math coprocessor (used for floating point
1716	  operations) if you don't have one. 486DX and Pentium processors have
1717	  a math coprocessor built in, 486SX and 386 do not, unless you added
1718	  a 487DX or 387, respectively. (The messages during boot time can
1719	  give you some hints here ["man dmesg"].) Everyone needs either a
1720	  coprocessor or this emulation.
1721
1722	  If you don't have a math coprocessor, you need to say Y here; if you
1723	  say Y here even though you have a coprocessor, the coprocessor will
1724	  be used nevertheless. (This behavior can be changed with the kernel
1725	  command line option "no387", which comes handy if your coprocessor
1726	  is broken. Try "man bootparam" or see the documentation of your boot
1727	  loader (lilo or loadlin) about how to pass options to the kernel at
1728	  boot time.) This means that it is a good idea to say Y here if you
1729	  intend to use this kernel on different machines.
1730
1731	  More information about the internals of the Linux math coprocessor
1732	  emulation can be found in <file:arch/x86/math-emu/README>.
1733
1734	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1735	  kernel, it won't hurt.
1736
1737config MTRR
1738	def_bool y
1739	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1740	help
1741	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1742	  the Memory Type Range Registers (MTRRs) may be used to control
1743	  processor access to memory ranges. This is most useful if you have
1744	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1745	  allows bus write transfers to be combined into a larger transfer
1746	  before bursting over the PCI/AGP bus. This can increase performance
1747	  of image write operations 2.5 times or more. Saying Y here creates a
1748	  /proc/mtrr file which may be used to manipulate your processor's
1749	  MTRRs. Typically the X server should use this.
1750
1751	  This code has a reasonably generic interface so that similar
1752	  control registers on other processors can be easily supported
1753	  as well:
1754
1755	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1756	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1757	  these, the ARRs are used to emulate the MTRRs.
1758	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1759	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1760	  write-combining. All of these processors are supported by this code
1761	  and it makes sense to say Y here if you have one of them.
1762
1763	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1764	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1765	  can lead to all sorts of problems, so it's good to say Y here.
1766
1767	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1768	  just add about 9 KB to your kernel.
1769
1770	  See <file:Documentation/x86/mtrr.rst> for more information.
1771
1772config MTRR_SANITIZER
1773	def_bool y
1774	prompt "MTRR cleanup support"
1775	depends on MTRR
1776	help
1777	  Convert MTRR layout from continuous to discrete, so X drivers can
1778	  add writeback entries.
1779
1780	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1781	  The largest mtrr entry size for a continuous block can be set with
1782	  mtrr_chunk_size.
1783
1784	  If unsure, say Y.
1785
1786config MTRR_SANITIZER_ENABLE_DEFAULT
1787	int "MTRR cleanup enable value (0-1)"
1788	range 0 1
1789	default "0"
1790	depends on MTRR_SANITIZER
1791	help
1792	  Enable mtrr cleanup default value
1793
1794config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1795	int "MTRR cleanup spare reg num (0-7)"
1796	range 0 7
1797	default "1"
1798	depends on MTRR_SANITIZER
1799	help
1800	  mtrr cleanup spare entries default, it can be changed via
1801	  mtrr_spare_reg_nr=N on the kernel command line.
1802
1803config X86_PAT
1804	def_bool y
1805	prompt "x86 PAT support" if EXPERT
1806	depends on MTRR
1807	help
1808	  Use PAT attributes to setup page level cache control.
1809
1810	  PATs are the modern equivalents of MTRRs and are much more
1811	  flexible than MTRRs.
1812
1813	  Say N here if you see bootup problems (boot crash, boot hang,
1814	  spontaneous reboots) or a non-working video driver.
1815
1816	  If unsure, say Y.
1817
1818config ARCH_USES_PG_UNCACHED
1819	def_bool y
1820	depends on X86_PAT
1821
1822config X86_UMIP
1823	def_bool y
1824	prompt "User Mode Instruction Prevention" if EXPERT
1825	help
1826	  User Mode Instruction Prevention (UMIP) is a security feature in
1827	  some x86 processors. If enabled, a general protection fault is
1828	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1829	  executed in user mode. These instructions unnecessarily expose
1830	  information about the hardware state.
1831
1832	  The vast majority of applications do not use these instructions.
1833	  For the very few that do, software emulation is provided in
1834	  specific cases in protected and virtual-8086 modes. Emulated
1835	  results are dummy.
1836
1837config CC_HAS_IBT
1838	# GCC >= 9 and binutils >= 2.29
1839	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1840	# Clang/LLVM >= 14
1841	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1842	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1843	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1844		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1845		  $(as-instr,endbr64)
1846
1847config X86_KERNEL_IBT
1848	prompt "Indirect Branch Tracking"
1849	bool
1850	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1851	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1852	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1853	select OBJTOOL
1854	help
1855	  Build the kernel with support for Indirect Branch Tracking, a
1856	  hardware support course-grain forward-edge Control Flow Integrity
1857	  protection. It enforces that all indirect calls must land on
1858	  an ENDBR instruction, as such, the compiler will instrument the
1859	  code with them to make this happen.
1860
1861	  In addition to building the kernel with IBT, seal all functions that
1862	  are not indirect call targets, avoiding them ever becoming one.
1863
1864	  This requires LTO like objtool runs and will slow down the build. It
1865	  does significantly reduce the number of ENDBR instructions in the
1866	  kernel image.
1867
1868config X86_INTEL_MEMORY_PROTECTION_KEYS
1869	prompt "Memory Protection Keys"
1870	def_bool y
1871	# Note: only available in 64-bit mode
1872	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1873	select ARCH_USES_HIGH_VMA_FLAGS
1874	select ARCH_HAS_PKEYS
1875	help
1876	  Memory Protection Keys provides a mechanism for enforcing
1877	  page-based protections, but without requiring modification of the
1878	  page tables when an application changes protection domains.
1879
1880	  For details, see Documentation/core-api/protection-keys.rst
1881
1882	  If unsure, say y.
1883
1884choice
1885	prompt "TSX enable mode"
1886	depends on CPU_SUP_INTEL
1887	default X86_INTEL_TSX_MODE_OFF
1888	help
1889	  Intel's TSX (Transactional Synchronization Extensions) feature
1890	  allows to optimize locking protocols through lock elision which
1891	  can lead to a noticeable performance boost.
1892
1893	  On the other hand it has been shown that TSX can be exploited
1894	  to form side channel attacks (e.g. TAA) and chances are there
1895	  will be more of those attacks discovered in the future.
1896
1897	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1898	  might override this decision by tsx=on the command line parameter.
1899	  Even with TSX enabled, the kernel will attempt to enable the best
1900	  possible TAA mitigation setting depending on the microcode available
1901	  for the particular machine.
1902
1903	  This option allows to set the default tsx mode between tsx=on, =off
1904	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1905	  details.
1906
1907	  Say off if not sure, auto if TSX is in use but it should be used on safe
1908	  platforms or on if TSX is in use and the security aspect of tsx is not
1909	  relevant.
1910
1911config X86_INTEL_TSX_MODE_OFF
1912	bool "off"
1913	help
1914	  TSX is disabled if possible - equals to tsx=off command line parameter.
1915
1916config X86_INTEL_TSX_MODE_ON
1917	bool "on"
1918	help
1919	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1920	  line parameter.
1921
1922config X86_INTEL_TSX_MODE_AUTO
1923	bool "auto"
1924	help
1925	  TSX is enabled on TSX capable HW that is believed to be safe against
1926	  side channel attacks- equals the tsx=auto command line parameter.
1927endchoice
1928
1929config X86_SGX
1930	bool "Software Guard eXtensions (SGX)"
1931	depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1932	depends on CRYPTO=y
1933	depends on CRYPTO_SHA256=y
1934	select SRCU
1935	select MMU_NOTIFIER
1936	select NUMA_KEEP_MEMINFO if NUMA
1937	select XARRAY_MULTI
1938	help
1939	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1940	  that can be used by applications to set aside private regions of code
1941	  and data, referred to as enclaves. An enclave's private memory can
1942	  only be accessed by code running within the enclave. Accesses from
1943	  outside the enclave, including other enclaves, are disallowed by
1944	  hardware.
1945
1946	  If unsure, say N.
1947
1948config EFI
1949	bool "EFI runtime service support"
1950	depends on ACPI
1951	select UCS2_STRING
1952	select EFI_RUNTIME_WRAPPERS
1953	select ARCH_USE_MEMREMAP_PROT
1954	help
1955	  This enables the kernel to use EFI runtime services that are
1956	  available (such as the EFI variable services).
1957
1958	  This option is only useful on systems that have EFI firmware.
1959	  In addition, you should use the latest ELILO loader available
1960	  at <http://elilo.sourceforge.net> in order to take advantage
1961	  of EFI runtime services. However, even with this option, the
1962	  resultant kernel should continue to boot on existing non-EFI
1963	  platforms.
1964
1965config EFI_STUB
1966	bool "EFI stub support"
1967	depends on EFI
1968	depends on $(cc-option,-mabi=ms) || X86_32
1969	select RELOCATABLE
1970	help
1971	  This kernel feature allows a bzImage to be loaded directly
1972	  by EFI firmware without the use of a bootloader.
1973
1974	  See Documentation/admin-guide/efi-stub.rst for more information.
1975
1976config EFI_MIXED
1977	bool "EFI mixed-mode support"
1978	depends on EFI_STUB && X86_64
1979	help
1980	  Enabling this feature allows a 64-bit kernel to be booted
1981	  on a 32-bit firmware, provided that your CPU supports 64-bit
1982	  mode.
1983
1984	  Note that it is not possible to boot a mixed-mode enabled
1985	  kernel via the EFI boot stub - a bootloader that supports
1986	  the EFI handover protocol must be used.
1987
1988	  If unsure, say N.
1989
1990source "kernel/Kconfig.hz"
1991
1992config KEXEC
1993	bool "kexec system call"
1994	select KEXEC_CORE
1995	help
1996	  kexec is a system call that implements the ability to shutdown your
1997	  current kernel, and to start another kernel.  It is like a reboot
1998	  but it is independent of the system firmware.   And like a reboot
1999	  you can start any kernel with it, not just Linux.
2000
2001	  The name comes from the similarity to the exec system call.
2002
2003	  It is an ongoing process to be certain the hardware in a machine
2004	  is properly shutdown, so do not be surprised if this code does not
2005	  initially work for you.  As of this writing the exact hardware
2006	  interface is strongly in flux, so no good recommendation can be
2007	  made.
2008
2009config KEXEC_FILE
2010	bool "kexec file based system call"
2011	select KEXEC_CORE
2012	select HAVE_IMA_KEXEC if IMA
2013	depends on X86_64
2014	depends on CRYPTO=y
2015	depends on CRYPTO_SHA256=y
2016	help
2017	  This is new version of kexec system call. This system call is
2018	  file based and takes file descriptors as system call argument
2019	  for kernel and initramfs as opposed to list of segments as
2020	  accepted by previous system call.
2021
2022config ARCH_HAS_KEXEC_PURGATORY
2023	def_bool KEXEC_FILE
2024
2025config KEXEC_SIG
2026	bool "Verify kernel signature during kexec_file_load() syscall"
2027	depends on KEXEC_FILE
2028	help
2029
2030	  This option makes the kexec_file_load() syscall check for a valid
2031	  signature of the kernel image.  The image can still be loaded without
2032	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2033	  there's a signature that we can check, then it must be valid.
2034
2035	  In addition to this option, you need to enable signature
2036	  verification for the corresponding kernel image type being
2037	  loaded in order for this to work.
2038
2039config KEXEC_SIG_FORCE
2040	bool "Require a valid signature in kexec_file_load() syscall"
2041	depends on KEXEC_SIG
2042	help
2043	  This option makes kernel signature verification mandatory for
2044	  the kexec_file_load() syscall.
2045
2046config KEXEC_BZIMAGE_VERIFY_SIG
2047	bool "Enable bzImage signature verification support"
2048	depends on KEXEC_SIG
2049	depends on SIGNED_PE_FILE_VERIFICATION
2050	select SYSTEM_TRUSTED_KEYRING
2051	help
2052	  Enable bzImage signature verification support.
2053
2054config CRASH_DUMP
2055	bool "kernel crash dumps"
2056	depends on X86_64 || (X86_32 && HIGHMEM)
2057	help
2058	  Generate crash dump after being started by kexec.
2059	  This should be normally only set in special crash dump kernels
2060	  which are loaded in the main kernel with kexec-tools into
2061	  a specially reserved region and then later executed after
2062	  a crash by kdump/kexec. The crash dump kernel must be compiled
2063	  to a memory address not used by the main kernel or BIOS using
2064	  PHYSICAL_START, or it must be built as a relocatable image
2065	  (CONFIG_RELOCATABLE=y).
2066	  For more details see Documentation/admin-guide/kdump/kdump.rst
2067
2068config KEXEC_JUMP
2069	bool "kexec jump"
2070	depends on KEXEC && HIBERNATION
2071	help
2072	  Jump between original kernel and kexeced kernel and invoke
2073	  code in physical address mode via KEXEC
2074
2075config PHYSICAL_START
2076	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2077	default "0x1000000"
2078	help
2079	  This gives the physical address where the kernel is loaded.
2080
2081	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2082	  bzImage will decompress itself to above physical address and
2083	  run from there. Otherwise, bzImage will run from the address where
2084	  it has been loaded by the boot loader and will ignore above physical
2085	  address.
2086
2087	  In normal kdump cases one does not have to set/change this option
2088	  as now bzImage can be compiled as a completely relocatable image
2089	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2090	  address. This option is mainly useful for the folks who don't want
2091	  to use a bzImage for capturing the crash dump and want to use a
2092	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2093	  to be specifically compiled to run from a specific memory area
2094	  (normally a reserved region) and this option comes handy.
2095
2096	  So if you are using bzImage for capturing the crash dump,
2097	  leave the value here unchanged to 0x1000000 and set
2098	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2099	  for capturing the crash dump change this value to start of
2100	  the reserved region.  In other words, it can be set based on
2101	  the "X" value as specified in the "crashkernel=YM@XM"
2102	  command line boot parameter passed to the panic-ed
2103	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2104	  for more details about crash dumps.
2105
2106	  Usage of bzImage for capturing the crash dump is recommended as
2107	  one does not have to build two kernels. Same kernel can be used
2108	  as production kernel and capture kernel. Above option should have
2109	  gone away after relocatable bzImage support is introduced. But it
2110	  is present because there are users out there who continue to use
2111	  vmlinux for dump capture. This option should go away down the
2112	  line.
2113
2114	  Don't change this unless you know what you are doing.
2115
2116config RELOCATABLE
2117	bool "Build a relocatable kernel"
2118	default y
2119	help
2120	  This builds a kernel image that retains relocation information
2121	  so it can be loaded someplace besides the default 1MB.
2122	  The relocations tend to make the kernel binary about 10% larger,
2123	  but are discarded at runtime.
2124
2125	  One use is for the kexec on panic case where the recovery kernel
2126	  must live at a different physical address than the primary
2127	  kernel.
2128
2129	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2130	  it has been loaded at and the compile time physical address
2131	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2132
2133config RANDOMIZE_BASE
2134	bool "Randomize the address of the kernel image (KASLR)"
2135	depends on RELOCATABLE
2136	default y
2137	help
2138	  In support of Kernel Address Space Layout Randomization (KASLR),
2139	  this randomizes the physical address at which the kernel image
2140	  is decompressed and the virtual address where the kernel
2141	  image is mapped, as a security feature that deters exploit
2142	  attempts relying on knowledge of the location of kernel
2143	  code internals.
2144
2145	  On 64-bit, the kernel physical and virtual addresses are
2146	  randomized separately. The physical address will be anywhere
2147	  between 16MB and the top of physical memory (up to 64TB). The
2148	  virtual address will be randomized from 16MB up to 1GB (9 bits
2149	  of entropy). Note that this also reduces the memory space
2150	  available to kernel modules from 1.5GB to 1GB.
2151
2152	  On 32-bit, the kernel physical and virtual addresses are
2153	  randomized together. They will be randomized from 16MB up to
2154	  512MB (8 bits of entropy).
2155
2156	  Entropy is generated using the RDRAND instruction if it is
2157	  supported. If RDTSC is supported, its value is mixed into
2158	  the entropy pool as well. If neither RDRAND nor RDTSC are
2159	  supported, then entropy is read from the i8254 timer. The
2160	  usable entropy is limited by the kernel being built using
2161	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2162	  minimum of 2MB. As a result, only 10 bits of entropy are
2163	  theoretically possible, but the implementations are further
2164	  limited due to memory layouts.
2165
2166	  If unsure, say Y.
2167
2168# Relocation on x86 needs some additional build support
2169config X86_NEED_RELOCS
2170	def_bool y
2171	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2172
2173config PHYSICAL_ALIGN
2174	hex "Alignment value to which kernel should be aligned"
2175	default "0x200000"
2176	range 0x2000 0x1000000 if X86_32
2177	range 0x200000 0x1000000 if X86_64
2178	help
2179	  This value puts the alignment restrictions on physical address
2180	  where kernel is loaded and run from. Kernel is compiled for an
2181	  address which meets above alignment restriction.
2182
2183	  If bootloader loads the kernel at a non-aligned address and
2184	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2185	  address aligned to above value and run from there.
2186
2187	  If bootloader loads the kernel at a non-aligned address and
2188	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2189	  load address and decompress itself to the address it has been
2190	  compiled for and run from there. The address for which kernel is
2191	  compiled already meets above alignment restrictions. Hence the
2192	  end result is that kernel runs from a physical address meeting
2193	  above alignment restrictions.
2194
2195	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2196	  this value must be a multiple of 0x200000.
2197
2198	  Don't change this unless you know what you are doing.
2199
2200config DYNAMIC_MEMORY_LAYOUT
2201	bool
2202	help
2203	  This option makes base addresses of vmalloc and vmemmap as well as
2204	  __PAGE_OFFSET movable during boot.
2205
2206config RANDOMIZE_MEMORY
2207	bool "Randomize the kernel memory sections"
2208	depends on X86_64
2209	depends on RANDOMIZE_BASE
2210	select DYNAMIC_MEMORY_LAYOUT
2211	default RANDOMIZE_BASE
2212	help
2213	  Randomizes the base virtual address of kernel memory sections
2214	  (physical memory mapping, vmalloc & vmemmap). This security feature
2215	  makes exploits relying on predictable memory locations less reliable.
2216
2217	  The order of allocations remains unchanged. Entropy is generated in
2218	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2219	  configuration have in average 30,000 different possible virtual
2220	  addresses for each memory section.
2221
2222	  If unsure, say Y.
2223
2224config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2225	hex "Physical memory mapping padding" if EXPERT
2226	depends on RANDOMIZE_MEMORY
2227	default "0xa" if MEMORY_HOTPLUG
2228	default "0x0"
2229	range 0x1 0x40 if MEMORY_HOTPLUG
2230	range 0x0 0x40
2231	help
2232	  Define the padding in terabytes added to the existing physical
2233	  memory size during kernel memory randomization. It is useful
2234	  for memory hotplug support but reduces the entropy available for
2235	  address randomization.
2236
2237	  If unsure, leave at the default value.
2238
2239config HOTPLUG_CPU
2240	def_bool y
2241	depends on SMP
2242
2243config BOOTPARAM_HOTPLUG_CPU0
2244	bool "Set default setting of cpu0_hotpluggable"
2245	depends on HOTPLUG_CPU
2246	help
2247	  Set whether default state of cpu0_hotpluggable is on or off.
2248
2249	  Say Y here to enable CPU0 hotplug by default. If this switch
2250	  is turned on, there is no need to give cpu0_hotplug kernel
2251	  parameter and the CPU0 hotplug feature is enabled by default.
2252
2253	  Please note: there are two known CPU0 dependencies if you want
2254	  to enable the CPU0 hotplug feature either by this switch or by
2255	  cpu0_hotplug kernel parameter.
2256
2257	  First, resume from hibernate or suspend always starts from CPU0.
2258	  So hibernate and suspend are prevented if CPU0 is offline.
2259
2260	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2261	  offline if any interrupt can not migrate out of CPU0. There may
2262	  be other CPU0 dependencies.
2263
2264	  Please make sure the dependencies are under your control before
2265	  you enable this feature.
2266
2267	  Say N if you don't want to enable CPU0 hotplug feature by default.
2268	  You still can enable the CPU0 hotplug feature at boot by kernel
2269	  parameter cpu0_hotplug.
2270
2271config DEBUG_HOTPLUG_CPU0
2272	def_bool n
2273	prompt "Debug CPU0 hotplug"
2274	depends on HOTPLUG_CPU
2275	help
2276	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2277	  soon as possible and boots up userspace with CPU0 offlined. User
2278	  can online CPU0 back after boot time.
2279
2280	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2281	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2282	  compilation or giving cpu0_hotplug kernel parameter at boot.
2283
2284	  If unsure, say N.
2285
2286config COMPAT_VDSO
2287	def_bool n
2288	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2289	depends on COMPAT_32
2290	help
2291	  Certain buggy versions of glibc will crash if they are
2292	  presented with a 32-bit vDSO that is not mapped at the address
2293	  indicated in its segment table.
2294
2295	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2296	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2297	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2298	  the only released version with the bug, but OpenSUSE 9
2299	  contains a buggy "glibc 2.3.2".
2300
2301	  The symptom of the bug is that everything crashes on startup, saying:
2302	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2303
2304	  Saying Y here changes the default value of the vdso32 boot
2305	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2306	  This works around the glibc bug but hurts performance.
2307
2308	  If unsure, say N: if you are compiling your own kernel, you
2309	  are unlikely to be using a buggy version of glibc.
2310
2311choice
2312	prompt "vsyscall table for legacy applications"
2313	depends on X86_64
2314	default LEGACY_VSYSCALL_XONLY
2315	help
2316	  Legacy user code that does not know how to find the vDSO expects
2317	  to be able to issue three syscalls by calling fixed addresses in
2318	  kernel space. Since this location is not randomized with ASLR,
2319	  it can be used to assist security vulnerability exploitation.
2320
2321	  This setting can be changed at boot time via the kernel command
2322	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2323	  is deprecated and can only be enabled using the kernel command
2324	  line.
2325
2326	  On a system with recent enough glibc (2.14 or newer) and no
2327	  static binaries, you can say None without a performance penalty
2328	  to improve security.
2329
2330	  If unsure, select "Emulate execution only".
2331
2332	config LEGACY_VSYSCALL_XONLY
2333		bool "Emulate execution only"
2334		help
2335		  The kernel traps and emulates calls into the fixed vsyscall
2336		  address mapping and does not allow reads.  This
2337		  configuration is recommended when userspace might use the
2338		  legacy vsyscall area but support for legacy binary
2339		  instrumentation of legacy code is not needed.  It mitigates
2340		  certain uses of the vsyscall area as an ASLR-bypassing
2341		  buffer.
2342
2343	config LEGACY_VSYSCALL_NONE
2344		bool "None"
2345		help
2346		  There will be no vsyscall mapping at all. This will
2347		  eliminate any risk of ASLR bypass due to the vsyscall
2348		  fixed address mapping. Attempts to use the vsyscalls
2349		  will be reported to dmesg, so that either old or
2350		  malicious userspace programs can be identified.
2351
2352endchoice
2353
2354config CMDLINE_BOOL
2355	bool "Built-in kernel command line"
2356	help
2357	  Allow for specifying boot arguments to the kernel at
2358	  build time.  On some systems (e.g. embedded ones), it is
2359	  necessary or convenient to provide some or all of the
2360	  kernel boot arguments with the kernel itself (that is,
2361	  to not rely on the boot loader to provide them.)
2362
2363	  To compile command line arguments into the kernel,
2364	  set this option to 'Y', then fill in the
2365	  boot arguments in CONFIG_CMDLINE.
2366
2367	  Systems with fully functional boot loaders (i.e. non-embedded)
2368	  should leave this option set to 'N'.
2369
2370config CMDLINE
2371	string "Built-in kernel command string"
2372	depends on CMDLINE_BOOL
2373	default ""
2374	help
2375	  Enter arguments here that should be compiled into the kernel
2376	  image and used at boot time.  If the boot loader provides a
2377	  command line at boot time, it is appended to this string to
2378	  form the full kernel command line, when the system boots.
2379
2380	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2381	  change this behavior.
2382
2383	  In most cases, the command line (whether built-in or provided
2384	  by the boot loader) should specify the device for the root
2385	  file system.
2386
2387config CMDLINE_OVERRIDE
2388	bool "Built-in command line overrides boot loader arguments"
2389	depends on CMDLINE_BOOL && CMDLINE != ""
2390	help
2391	  Set this option to 'Y' to have the kernel ignore the boot loader
2392	  command line, and use ONLY the built-in command line.
2393
2394	  This is used to work around broken boot loaders.  This should
2395	  be set to 'N' under normal conditions.
2396
2397config MODIFY_LDT_SYSCALL
2398	bool "Enable the LDT (local descriptor table)" if EXPERT
2399	default y
2400	help
2401	  Linux can allow user programs to install a per-process x86
2402	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2403	  call.  This is required to run 16-bit or segmented code such as
2404	  DOSEMU or some Wine programs.  It is also used by some very old
2405	  threading libraries.
2406
2407	  Enabling this feature adds a small amount of overhead to
2408	  context switches and increases the low-level kernel attack
2409	  surface.  Disabling it removes the modify_ldt(2) system call.
2410
2411	  Saying 'N' here may make sense for embedded or server kernels.
2412
2413config STRICT_SIGALTSTACK_SIZE
2414	bool "Enforce strict size checking for sigaltstack"
2415	depends on DYNAMIC_SIGFRAME
2416	help
2417	  For historical reasons MINSIGSTKSZ is a constant which became
2418	  already too small with AVX512 support. Add a mechanism to
2419	  enforce strict checking of the sigaltstack size against the
2420	  real size of the FPU frame. This option enables the check
2421	  by default. It can also be controlled via the kernel command
2422	  line option 'strict_sas_size' independent of this config
2423	  switch. Enabling it might break existing applications which
2424	  allocate a too small sigaltstack but 'work' because they
2425	  never get a signal delivered.
2426
2427	  Say 'N' unless you want to really enforce this check.
2428
2429source "kernel/livepatch/Kconfig"
2430
2431endmenu
2432
2433config CC_HAS_SLS
2434	def_bool $(cc-option,-mharden-sls=all)
2435
2436config CC_HAS_RETURN_THUNK
2437	def_bool $(cc-option,-mfunction-return=thunk-extern)
2438
2439menuconfig SPECULATION_MITIGATIONS
2440	bool "Mitigations for speculative execution vulnerabilities"
2441	default y
2442	help
2443	  Say Y here to enable options which enable mitigations for
2444	  speculative execution hardware vulnerabilities.
2445
2446	  If you say N, all mitigations will be disabled. You really
2447	  should know what you are doing to say so.
2448
2449if SPECULATION_MITIGATIONS
2450
2451config PAGE_TABLE_ISOLATION
2452	bool "Remove the kernel mapping in user mode"
2453	default y
2454	depends on (X86_64 || X86_PAE)
2455	help
2456	  This feature reduces the number of hardware side channels by
2457	  ensuring that the majority of kernel addresses are not mapped
2458	  into userspace.
2459
2460	  See Documentation/x86/pti.rst for more details.
2461
2462config RETPOLINE
2463	bool "Avoid speculative indirect branches in kernel"
2464	select OBJTOOL if HAVE_OBJTOOL
2465	default y
2466	help
2467	  Compile kernel with the retpoline compiler options to guard against
2468	  kernel-to-user data leaks by avoiding speculative indirect
2469	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2470	  support for full protection. The kernel may run slower.
2471
2472config RETHUNK
2473	bool "Enable return-thunks"
2474	depends on RETPOLINE && CC_HAS_RETURN_THUNK
2475	select OBJTOOL if HAVE_OBJTOOL
2476	default y if X86_64
2477	help
2478	  Compile the kernel with the return-thunks compiler option to guard
2479	  against kernel-to-user data leaks by avoiding return speculation.
2480	  Requires a compiler with -mfunction-return=thunk-extern
2481	  support for full protection. The kernel may run slower.
2482
2483config CPU_UNRET_ENTRY
2484	bool "Enable UNRET on kernel entry"
2485	depends on CPU_SUP_AMD && RETHUNK && X86_64
2486	default y
2487	help
2488	  Compile the kernel with support for the retbleed=unret mitigation.
2489
2490config CPU_IBPB_ENTRY
2491	bool "Enable IBPB on kernel entry"
2492	depends on CPU_SUP_AMD && X86_64
2493	default y
2494	help
2495	  Compile the kernel with support for the retbleed=ibpb mitigation.
2496
2497config CPU_IBRS_ENTRY
2498	bool "Enable IBRS on kernel entry"
2499	depends on CPU_SUP_INTEL && X86_64
2500	default y
2501	help
2502	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2503	  This mitigates both spectre_v2 and retbleed at great cost to
2504	  performance.
2505
2506config SLS
2507	bool "Mitigate Straight-Line-Speculation"
2508	depends on CC_HAS_SLS && X86_64
2509	select OBJTOOL if HAVE_OBJTOOL
2510	default n
2511	help
2512	  Compile the kernel with straight-line-speculation options to guard
2513	  against straight line speculation. The kernel image might be slightly
2514	  larger.
2515
2516endif
2517
2518config ARCH_HAS_ADD_PAGES
2519	def_bool y
2520	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2521
2522config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2523	def_bool y
2524
2525menu "Power management and ACPI options"
2526
2527config ARCH_HIBERNATION_HEADER
2528	def_bool y
2529	depends on HIBERNATION
2530
2531source "kernel/power/Kconfig"
2532
2533source "drivers/acpi/Kconfig"
2534
2535config X86_APM_BOOT
2536	def_bool y
2537	depends on APM
2538
2539menuconfig APM
2540	tristate "APM (Advanced Power Management) BIOS support"
2541	depends on X86_32 && PM_SLEEP
2542	help
2543	  APM is a BIOS specification for saving power using several different
2544	  techniques. This is mostly useful for battery powered laptops with
2545	  APM compliant BIOSes. If you say Y here, the system time will be
2546	  reset after a RESUME operation, the /proc/apm device will provide
2547	  battery status information, and user-space programs will receive
2548	  notification of APM "events" (e.g. battery status change).
2549
2550	  If you select "Y" here, you can disable actual use of the APM
2551	  BIOS by passing the "apm=off" option to the kernel at boot time.
2552
2553	  Note that the APM support is almost completely disabled for
2554	  machines with more than one CPU.
2555
2556	  In order to use APM, you will need supporting software. For location
2557	  and more information, read <file:Documentation/power/apm-acpi.rst>
2558	  and the Battery Powered Linux mini-HOWTO, available from
2559	  <http://www.tldp.org/docs.html#howto>.
2560
2561	  This driver does not spin down disk drives (see the hdparm(8)
2562	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2563	  VESA-compliant "green" monitors.
2564
2565	  This driver does not support the TI 4000M TravelMate and the ACER
2566	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2567	  desktop machines also don't have compliant BIOSes, and this driver
2568	  may cause those machines to panic during the boot phase.
2569
2570	  Generally, if you don't have a battery in your machine, there isn't
2571	  much point in using this driver and you should say N. If you get
2572	  random kernel OOPSes or reboots that don't seem to be related to
2573	  anything, try disabling/enabling this option (or disabling/enabling
2574	  APM in your BIOS).
2575
2576	  Some other things you should try when experiencing seemingly random,
2577	  "weird" problems:
2578
2579	  1) make sure that you have enough swap space and that it is
2580	  enabled.
2581	  2) pass the "idle=poll" option to the kernel
2582	  3) switch on floating point emulation in the kernel and pass
2583	  the "no387" option to the kernel
2584	  4) pass the "floppy=nodma" option to the kernel
2585	  5) pass the "mem=4M" option to the kernel (thereby disabling
2586	  all but the first 4 MB of RAM)
2587	  6) make sure that the CPU is not over clocked.
2588	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2589	  8) disable the cache from your BIOS settings
2590	  9) install a fan for the video card or exchange video RAM
2591	  10) install a better fan for the CPU
2592	  11) exchange RAM chips
2593	  12) exchange the motherboard.
2594
2595	  To compile this driver as a module, choose M here: the
2596	  module will be called apm.
2597
2598if APM
2599
2600config APM_IGNORE_USER_SUSPEND
2601	bool "Ignore USER SUSPEND"
2602	help
2603	  This option will ignore USER SUSPEND requests. On machines with a
2604	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2605	  series notebooks, it is necessary to say Y because of a BIOS bug.
2606
2607config APM_DO_ENABLE
2608	bool "Enable PM at boot time"
2609	help
2610	  Enable APM features at boot time. From page 36 of the APM BIOS
2611	  specification: "When disabled, the APM BIOS does not automatically
2612	  power manage devices, enter the Standby State, enter the Suspend
2613	  State, or take power saving steps in response to CPU Idle calls."
2614	  This driver will make CPU Idle calls when Linux is idle (unless this
2615	  feature is turned off -- see "Do CPU IDLE calls", below). This
2616	  should always save battery power, but more complicated APM features
2617	  will be dependent on your BIOS implementation. You may need to turn
2618	  this option off if your computer hangs at boot time when using APM
2619	  support, or if it beeps continuously instead of suspending. Turn
2620	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2621	  T400CDT. This is off by default since most machines do fine without
2622	  this feature.
2623
2624config APM_CPU_IDLE
2625	depends on CPU_IDLE
2626	bool "Make CPU Idle calls when idle"
2627	help
2628	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2629	  On some machines, this can activate improved power savings, such as
2630	  a slowed CPU clock rate, when the machine is idle. These idle calls
2631	  are made after the idle loop has run for some length of time (e.g.,
2632	  333 mS). On some machines, this will cause a hang at boot time or
2633	  whenever the CPU becomes idle. (On machines with more than one CPU,
2634	  this option does nothing.)
2635
2636config APM_DISPLAY_BLANK
2637	bool "Enable console blanking using APM"
2638	help
2639	  Enable console blanking using the APM. Some laptops can use this to
2640	  turn off the LCD backlight when the screen blanker of the Linux
2641	  virtual console blanks the screen. Note that this is only used by
2642	  the virtual console screen blanker, and won't turn off the backlight
2643	  when using the X Window system. This also doesn't have anything to
2644	  do with your VESA-compliant power-saving monitor. Further, this
2645	  option doesn't work for all laptops -- it might not turn off your
2646	  backlight at all, or it might print a lot of errors to the console,
2647	  especially if you are using gpm.
2648
2649config APM_ALLOW_INTS
2650	bool "Allow interrupts during APM BIOS calls"
2651	help
2652	  Normally we disable external interrupts while we are making calls to
2653	  the APM BIOS as a measure to lessen the effects of a badly behaving
2654	  BIOS implementation.  The BIOS should reenable interrupts if it
2655	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2656	  many of the newer IBM Thinkpads.  If you experience hangs when you
2657	  suspend, try setting this to Y.  Otherwise, say N.
2658
2659endif # APM
2660
2661source "drivers/cpufreq/Kconfig"
2662
2663source "drivers/cpuidle/Kconfig"
2664
2665source "drivers/idle/Kconfig"
2666
2667endmenu
2668
2669menu "Bus options (PCI etc.)"
2670
2671choice
2672	prompt "PCI access mode"
2673	depends on X86_32 && PCI
2674	default PCI_GOANY
2675	help
2676	  On PCI systems, the BIOS can be used to detect the PCI devices and
2677	  determine their configuration. However, some old PCI motherboards
2678	  have BIOS bugs and may crash if this is done. Also, some embedded
2679	  PCI-based systems don't have any BIOS at all. Linux can also try to
2680	  detect the PCI hardware directly without using the BIOS.
2681
2682	  With this option, you can specify how Linux should detect the
2683	  PCI devices. If you choose "BIOS", the BIOS will be used,
2684	  if you choose "Direct", the BIOS won't be used, and if you
2685	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2686	  If you choose "Any", the kernel will try MMCONFIG, then the
2687	  direct access method and falls back to the BIOS if that doesn't
2688	  work. If unsure, go with the default, which is "Any".
2689
2690config PCI_GOBIOS
2691	bool "BIOS"
2692
2693config PCI_GOMMCONFIG
2694	bool "MMConfig"
2695
2696config PCI_GODIRECT
2697	bool "Direct"
2698
2699config PCI_GOOLPC
2700	bool "OLPC XO-1"
2701	depends on OLPC
2702
2703config PCI_GOANY
2704	bool "Any"
2705
2706endchoice
2707
2708config PCI_BIOS
2709	def_bool y
2710	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2711
2712# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2713config PCI_DIRECT
2714	def_bool y
2715	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2716
2717config PCI_MMCONFIG
2718	bool "Support mmconfig PCI config space access" if X86_64
2719	default y
2720	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2721	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2722
2723config PCI_OLPC
2724	def_bool y
2725	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2726
2727config PCI_XEN
2728	def_bool y
2729	depends on PCI && XEN
2730
2731config MMCONF_FAM10H
2732	def_bool y
2733	depends on X86_64 && PCI_MMCONFIG && ACPI
2734
2735config PCI_CNB20LE_QUIRK
2736	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2737	depends on PCI
2738	help
2739	  Read the PCI windows out of the CNB20LE host bridge. This allows
2740	  PCI hotplug to work on systems with the CNB20LE chipset which do
2741	  not have ACPI.
2742
2743	  There's no public spec for this chipset, and this functionality
2744	  is known to be incomplete.
2745
2746	  You should say N unless you know you need this.
2747
2748config ISA_BUS
2749	bool "ISA bus support on modern systems" if EXPERT
2750	help
2751	  Expose ISA bus device drivers and options available for selection and
2752	  configuration. Enable this option if your target machine has an ISA
2753	  bus. ISA is an older system, displaced by PCI and newer bus
2754	  architectures -- if your target machine is modern, it probably does
2755	  not have an ISA bus.
2756
2757	  If unsure, say N.
2758
2759# x86_64 have no ISA slots, but can have ISA-style DMA.
2760config ISA_DMA_API
2761	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2762	default y
2763	help
2764	  Enables ISA-style DMA support for devices requiring such controllers.
2765	  If unsure, say Y.
2766
2767if X86_32
2768
2769config ISA
2770	bool "ISA support"
2771	help
2772	  Find out whether you have ISA slots on your motherboard.  ISA is the
2773	  name of a bus system, i.e. the way the CPU talks to the other stuff
2774	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2775	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2776	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2777
2778config SCx200
2779	tristate "NatSemi SCx200 support"
2780	help
2781	  This provides basic support for National Semiconductor's
2782	  (now AMD's) Geode processors.  The driver probes for the
2783	  PCI-IDs of several on-chip devices, so its a good dependency
2784	  for other scx200_* drivers.
2785
2786	  If compiled as a module, the driver is named scx200.
2787
2788config SCx200HR_TIMER
2789	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2790	depends on SCx200
2791	default y
2792	help
2793	  This driver provides a clocksource built upon the on-chip
2794	  27MHz high-resolution timer.  Its also a workaround for
2795	  NSC Geode SC-1100's buggy TSC, which loses time when the
2796	  processor goes idle (as is done by the scheduler).  The
2797	  other workaround is idle=poll boot option.
2798
2799config OLPC
2800	bool "One Laptop Per Child support"
2801	depends on !X86_PAE
2802	select GPIOLIB
2803	select OF
2804	select OF_PROMTREE
2805	select IRQ_DOMAIN
2806	select OLPC_EC
2807	help
2808	  Add support for detecting the unique features of the OLPC
2809	  XO hardware.
2810
2811config OLPC_XO1_PM
2812	bool "OLPC XO-1 Power Management"
2813	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2814	help
2815	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2816
2817config OLPC_XO1_RTC
2818	bool "OLPC XO-1 Real Time Clock"
2819	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2820	help
2821	  Add support for the XO-1 real time clock, which can be used as a
2822	  programmable wakeup source.
2823
2824config OLPC_XO1_SCI
2825	bool "OLPC XO-1 SCI extras"
2826	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2827	depends on INPUT=y
2828	select POWER_SUPPLY
2829	help
2830	  Add support for SCI-based features of the OLPC XO-1 laptop:
2831	   - EC-driven system wakeups
2832	   - Power button
2833	   - Ebook switch
2834	   - Lid switch
2835	   - AC adapter status updates
2836	   - Battery status updates
2837
2838config OLPC_XO15_SCI
2839	bool "OLPC XO-1.5 SCI extras"
2840	depends on OLPC && ACPI
2841	select POWER_SUPPLY
2842	help
2843	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2844	   - EC-driven system wakeups
2845	   - AC adapter status updates
2846	   - Battery status updates
2847
2848config ALIX
2849	bool "PCEngines ALIX System Support (LED setup)"
2850	select GPIOLIB
2851	help
2852	  This option enables system support for the PCEngines ALIX.
2853	  At present this just sets up LEDs for GPIO control on
2854	  ALIX2/3/6 boards.  However, other system specific setup should
2855	  get added here.
2856
2857	  Note: You must still enable the drivers for GPIO and LED support
2858	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2859
2860	  Note: You have to set alix.force=1 for boards with Award BIOS.
2861
2862config NET5501
2863	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2864	select GPIOLIB
2865	help
2866	  This option enables system support for the Soekris Engineering net5501.
2867
2868config GEOS
2869	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2870	select GPIOLIB
2871	depends on DMI
2872	help
2873	  This option enables system support for the Traverse Technologies GEOS.
2874
2875config TS5500
2876	bool "Technologic Systems TS-5500 platform support"
2877	depends on MELAN
2878	select CHECK_SIGNATURE
2879	select NEW_LEDS
2880	select LEDS_CLASS
2881	help
2882	  This option enables system support for the Technologic Systems TS-5500.
2883
2884endif # X86_32
2885
2886config AMD_NB
2887	def_bool y
2888	depends on CPU_SUP_AMD && PCI
2889
2890endmenu
2891
2892menu "Binary Emulations"
2893
2894config IA32_EMULATION
2895	bool "IA32 Emulation"
2896	depends on X86_64
2897	select ARCH_WANT_OLD_COMPAT_IPC
2898	select BINFMT_ELF
2899	select COMPAT_OLD_SIGACTION
2900	help
2901	  Include code to run legacy 32-bit programs under a
2902	  64-bit kernel. You should likely turn this on, unless you're
2903	  100% sure that you don't have any 32-bit programs left.
2904
2905config X86_X32_ABI
2906	bool "x32 ABI for 64-bit mode"
2907	depends on X86_64
2908	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2909	# compressed debug sections to x86_x32 properly:
2910	# https://github.com/ClangBuiltLinux/linux/issues/514
2911	# https://github.com/ClangBuiltLinux/linux/issues/1141
2912	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2913	help
2914	  Include code to run binaries for the x32 native 32-bit ABI
2915	  for 64-bit processors.  An x32 process gets access to the
2916	  full 64-bit register file and wide data path while leaving
2917	  pointers at 32 bits for smaller memory footprint.
2918
2919config COMPAT_32
2920	def_bool y
2921	depends on IA32_EMULATION || X86_32
2922	select HAVE_UID16
2923	select OLD_SIGSUSPEND3
2924
2925config COMPAT
2926	def_bool y
2927	depends on IA32_EMULATION || X86_X32_ABI
2928
2929config COMPAT_FOR_U64_ALIGNMENT
2930	def_bool y
2931	depends on COMPAT
2932
2933endmenu
2934
2935config HAVE_ATOMIC_IOMAP
2936	def_bool y
2937	depends on X86_32
2938
2939source "arch/x86/kvm/Kconfig"
2940
2941source "arch/x86/Kconfig.assembler"
2942