xref: /linux/arch/x86/Kconfig (revision fdaf9a5840acaab18694a19e0eb0aa51162eeeed)
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_FILTER_PGPROT
80	select ARCH_HAS_FORTIFY_SOURCE
81	select ARCH_HAS_GCOV_PROFILE_ALL
82	select ARCH_HAS_KCOV			if X86_64
83	select ARCH_HAS_MEM_ENCRYPT
84	select ARCH_HAS_MEMBARRIER_SYNC_CORE
85	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
86	select ARCH_HAS_PMEM_API		if X86_64
87	select ARCH_HAS_PTE_DEVMAP		if X86_64
88	select ARCH_HAS_PTE_SPECIAL
89	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
90	select ARCH_HAS_COPY_MC			if X86_64
91	select ARCH_HAS_SET_MEMORY
92	select ARCH_HAS_SET_DIRECT_MAP
93	select ARCH_HAS_STRICT_KERNEL_RWX
94	select ARCH_HAS_STRICT_MODULE_RWX
95	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
96	select ARCH_HAS_SYSCALL_WRAPPER
97	select ARCH_HAS_UBSAN_SANITIZE_ALL
98	select ARCH_HAS_DEBUG_WX
99	select ARCH_HAS_ZONE_DMA_SET if EXPERT
100	select ARCH_HAVE_NMI_SAFE_CMPXCHG
101	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
102	select ARCH_MIGHT_HAVE_PC_PARPORT
103	select ARCH_MIGHT_HAVE_PC_SERIO
104	select ARCH_STACKWALK
105	select ARCH_SUPPORTS_ACPI
106	select ARCH_SUPPORTS_ATOMIC_RMW
107	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
108	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
109	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
110	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
111	select ARCH_SUPPORTS_LTO_CLANG
112	select ARCH_SUPPORTS_LTO_CLANG_THIN
113	select ARCH_USE_BUILTIN_BSWAP
114	select ARCH_USE_MEMTEST
115	select ARCH_USE_QUEUED_RWLOCKS
116	select ARCH_USE_QUEUED_SPINLOCKS
117	select ARCH_USE_SYM_ANNOTATIONS
118	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
119	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
120	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
121	select ARCH_WANTS_NO_INSTR
122	select ARCH_WANT_GENERAL_HUGETLB
123	select ARCH_WANT_HUGE_PMD_SHARE
124	select ARCH_WANT_LD_ORPHAN_WARN
125	select ARCH_WANTS_THP_SWAP		if X86_64
126	select ARCH_HAS_PARANOID_L1D_FLUSH
127	select BUILDTIME_TABLE_SORT
128	select CLKEVT_I8253
129	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
130	select CLOCKSOURCE_WATCHDOG
131	select DCACHE_WORD_ACCESS
132	select DYNAMIC_SIGFRAME
133	select EDAC_ATOMIC_SCRUB
134	select EDAC_SUPPORT
135	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
136	select GENERIC_CLOCKEVENTS_MIN_ADJUST
137	select GENERIC_CMOS_UPDATE
138	select GENERIC_CPU_AUTOPROBE
139	select GENERIC_CPU_VULNERABILITIES
140	select GENERIC_EARLY_IOREMAP
141	select GENERIC_ENTRY
142	select GENERIC_IOMAP
143	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
144	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
145	select GENERIC_IRQ_MIGRATION		if SMP
146	select GENERIC_IRQ_PROBE
147	select GENERIC_IRQ_RESERVATION_MODE
148	select GENERIC_IRQ_SHOW
149	select GENERIC_PENDING_IRQ		if SMP
150	select GENERIC_PTDUMP
151	select GENERIC_SMP_IDLE_THREAD
152	select GENERIC_TIME_VSYSCALL
153	select GENERIC_GETTIMEOFDAY
154	select GENERIC_VDSO_TIME_NS
155	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
156	select HARDIRQS_SW_RESEND
157	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
158	select HAVE_ACPI_APEI			if ACPI
159	select HAVE_ACPI_APEI_NMI		if ACPI
160	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
161	select HAVE_ARCH_AUDITSYSCALL
162	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
163	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
164	select HAVE_ARCH_JUMP_LABEL
165	select HAVE_ARCH_JUMP_LABEL_RELATIVE
166	select HAVE_ARCH_KASAN			if X86_64
167	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
168	select HAVE_ARCH_KFENCE
169	select HAVE_ARCH_KGDB
170	select HAVE_ARCH_MMAP_RND_BITS		if MMU
171	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
172	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
173	select HAVE_ARCH_PREL32_RELOCATIONS
174	select HAVE_ARCH_SECCOMP_FILTER
175	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
176	select HAVE_ARCH_STACKLEAK
177	select HAVE_ARCH_TRACEHOOK
178	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
179	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
180	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
181	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
182	select HAVE_ARCH_VMAP_STACK		if X86_64
183	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
184	select HAVE_ARCH_WITHIN_STACK_FRAMES
185	select HAVE_ASM_MODVERSIONS
186	select HAVE_CMPXCHG_DOUBLE
187	select HAVE_CMPXCHG_LOCAL
188	select HAVE_CONTEXT_TRACKING		if X86_64
189	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
190	select HAVE_C_RECORDMCOUNT
191	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
192	select HAVE_BUILDTIME_MCOUNT_SORT
193	select HAVE_DEBUG_KMEMLEAK
194	select HAVE_DMA_CONTIGUOUS
195	select HAVE_DYNAMIC_FTRACE
196	select HAVE_DYNAMIC_FTRACE_WITH_REGS
197	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
198	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
199	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
200	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
201	select HAVE_EBPF_JIT
202	select HAVE_EFFICIENT_UNALIGNED_ACCESS
203	select HAVE_EISA
204	select HAVE_EXIT_THREAD
205	select HAVE_FAST_GUP
206	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
207	select HAVE_FTRACE_MCOUNT_RECORD
208	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
209	select HAVE_FUNCTION_TRACER
210	select HAVE_GCC_PLUGINS
211	select HAVE_HW_BREAKPOINT
212	select HAVE_IOREMAP_PROT
213	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
214	select HAVE_IRQ_TIME_ACCOUNTING
215	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
216	select HAVE_KERNEL_BZIP2
217	select HAVE_KERNEL_GZIP
218	select HAVE_KERNEL_LZ4
219	select HAVE_KERNEL_LZMA
220	select HAVE_KERNEL_LZO
221	select HAVE_KERNEL_XZ
222	select HAVE_KERNEL_ZSTD
223	select HAVE_KPROBES
224	select HAVE_KPROBES_ON_FTRACE
225	select HAVE_FUNCTION_ERROR_INJECTION
226	select HAVE_KRETPROBES
227	select HAVE_RETHOOK
228	select HAVE_KVM
229	select HAVE_LIVEPATCH			if X86_64
230	select HAVE_MIXED_BREAKPOINTS_REGS
231	select HAVE_MOD_ARCH_SPECIFIC
232	select HAVE_MOVE_PMD
233	select HAVE_MOVE_PUD
234	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
235	select HAVE_NMI
236	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
237	select HAVE_OBJTOOL			if X86_64
238	select HAVE_OPTPROBES
239	select HAVE_PCSPKR_PLATFORM
240	select HAVE_PERF_EVENTS
241	select HAVE_PERF_EVENTS_NMI
242	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
243	select HAVE_PCI
244	select HAVE_PERF_REGS
245	select HAVE_PERF_USER_STACK_DUMP
246	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
247	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
248	select HAVE_REGS_AND_STACK_ACCESS_API
249	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
250	select HAVE_FUNCTION_ARG_ACCESS_API
251	select HAVE_SETUP_PER_CPU_AREA
252	select HAVE_SOFTIRQ_ON_OWN_STACK
253	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
254	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
255	select HAVE_STATIC_CALL
256	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
257	select HAVE_PREEMPT_DYNAMIC_CALL
258	select HAVE_RSEQ
259	select HAVE_SYSCALL_TRACEPOINTS
260	select HAVE_UNSTABLE_SCHED_CLOCK
261	select HAVE_USER_RETURN_NOTIFIER
262	select HAVE_GENERIC_VDSO
263	select HOTPLUG_SMT			if SMP
264	select IRQ_FORCED_THREADING
265	select NEED_PER_CPU_EMBED_FIRST_CHUNK
266	select NEED_PER_CPU_PAGE_FIRST_CHUNK
267	select NEED_SG_DMA_LENGTH
268	select PCI_DOMAINS			if PCI
269	select PCI_LOCKLESS_CONFIG		if PCI
270	select PERF_EVENTS
271	select RTC_LIB
272	select RTC_MC146818_LIB
273	select SPARSE_IRQ
274	select SRCU
275	select SYSCTL_EXCEPTION_TRACE
276	select THREAD_INFO_IN_TASK
277	select TRACE_IRQFLAGS_SUPPORT
278	select USER_STACKTRACE_SUPPORT
279	select VIRT_TO_BUS
280	select HAVE_ARCH_KCSAN			if X86_64
281	select X86_FEATURE_NAMES		if PROC_FS
282	select PROC_PID_ARCH_STATUS		if PROC_FS
283	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
284	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
285
286config INSTRUCTION_DECODER
287	def_bool y
288	depends on KPROBES || PERF_EVENTS || UPROBES
289
290config OUTPUT_FORMAT
291	string
292	default "elf32-i386" if X86_32
293	default "elf64-x86-64" if X86_64
294
295config LOCKDEP_SUPPORT
296	def_bool y
297
298config STACKTRACE_SUPPORT
299	def_bool y
300
301config MMU
302	def_bool y
303
304config ARCH_MMAP_RND_BITS_MIN
305	default 28 if 64BIT
306	default 8
307
308config ARCH_MMAP_RND_BITS_MAX
309	default 32 if 64BIT
310	default 16
311
312config ARCH_MMAP_RND_COMPAT_BITS_MIN
313	default 8
314
315config ARCH_MMAP_RND_COMPAT_BITS_MAX
316	default 16
317
318config SBUS
319	bool
320
321config GENERIC_ISA_DMA
322	def_bool y
323	depends on ISA_DMA_API
324
325config GENERIC_BUG
326	def_bool y
327	depends on BUG
328	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
329
330config GENERIC_BUG_RELATIVE_POINTERS
331	bool
332
333config ARCH_MAY_HAVE_PC_FDC
334	def_bool y
335	depends on ISA_DMA_API
336
337config GENERIC_CALIBRATE_DELAY
338	def_bool y
339
340config ARCH_HAS_CPU_RELAX
341	def_bool y
342
343config ARCH_HIBERNATION_POSSIBLE
344	def_bool y
345
346config ARCH_NR_GPIO
347	int
348	default 1024 if X86_64
349	default 512
350
351config ARCH_SUSPEND_POSSIBLE
352	def_bool y
353
354config AUDIT_ARCH
355	def_bool y if X86_64
356
357config KASAN_SHADOW_OFFSET
358	hex
359	depends on KASAN
360	default 0xdffffc0000000000
361
362config HAVE_INTEL_TXT
363	def_bool y
364	depends on INTEL_IOMMU && ACPI
365
366config X86_32_SMP
367	def_bool y
368	depends on X86_32 && SMP
369
370config X86_64_SMP
371	def_bool y
372	depends on X86_64 && SMP
373
374config ARCH_SUPPORTS_UPROBES
375	def_bool y
376
377config FIX_EARLYCON_MEM
378	def_bool y
379
380config DYNAMIC_PHYSICAL_MASK
381	bool
382
383config PGTABLE_LEVELS
384	int
385	default 5 if X86_5LEVEL
386	default 4 if X86_64
387	default 3 if X86_PAE
388	default 2
389
390config CC_HAS_SANE_STACKPROTECTOR
391	bool
392	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
393	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
394	help
395	   We have to make sure stack protector is unconditionally disabled if
396	   the compiler produces broken code or if it does not let us control
397	   the segment on 32-bit kernels.
398
399menu "Processor type and features"
400
401config SMP
402	bool "Symmetric multi-processing support"
403	help
404	  This enables support for systems with more than one CPU. If you have
405	  a system with only one CPU, say N. If you have a system with more
406	  than one CPU, say Y.
407
408	  If you say N here, the kernel will run on uni- and multiprocessor
409	  machines, but will use only one CPU of a multiprocessor machine. If
410	  you say Y here, the kernel will run on many, but not all,
411	  uniprocessor machines. On a uniprocessor machine, the kernel
412	  will run faster if you say N here.
413
414	  Note that if you say Y here and choose architecture "586" or
415	  "Pentium" under "Processor family", the kernel will not work on 486
416	  architectures. Similarly, multiprocessor kernels for the "PPro"
417	  architecture may not work on all Pentium based boards.
418
419	  People using multiprocessor machines who say Y here should also say
420	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
421	  Management" code will be disabled if you say Y here.
422
423	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
424	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
425	  <http://www.tldp.org/docs.html#howto>.
426
427	  If you don't know what to do here, say N.
428
429config X86_FEATURE_NAMES
430	bool "Processor feature human-readable names" if EMBEDDED
431	default y
432	help
433	  This option compiles in a table of x86 feature bits and corresponding
434	  names.  This is required to support /proc/cpuinfo and a few kernel
435	  messages.  You can disable this to save space, at the expense of
436	  making those few kernel messages show numeric feature bits instead.
437
438	  If in doubt, say Y.
439
440config X86_X2APIC
441	bool "Support x2apic"
442	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
443	help
444	  This enables x2apic support on CPUs that have this feature.
445
446	  This allows 32-bit apic IDs (so it can support very large systems),
447	  and accesses the local apic via MSRs not via mmio.
448
449	  If you don't know what to do here, say N.
450
451config X86_MPPARSE
452	bool "Enable MPS table" if ACPI
453	default y
454	depends on X86_LOCAL_APIC
455	help
456	  For old smp systems that do not have proper acpi support. Newer systems
457	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
458
459config GOLDFISH
460	def_bool y
461	depends on X86_GOLDFISH
462
463config RETPOLINE
464	bool "Avoid speculative indirect branches in kernel"
465	select OBJTOOL if HAVE_OBJTOOL
466	default y
467	help
468	  Compile kernel with the retpoline compiler options to guard against
469	  kernel-to-user data leaks by avoiding speculative indirect
470	  branches. Requires a compiler with -mindirect-branch=thunk-extern
471	  support for full protection. The kernel may run slower.
472
473config CC_HAS_SLS
474	def_bool $(cc-option,-mharden-sls=all)
475
476config SLS
477	bool "Mitigate Straight-Line-Speculation"
478	depends on CC_HAS_SLS && X86_64
479	select OBJTOOL if HAVE_OBJTOOL
480	default n
481	help
482	  Compile the kernel with straight-line-speculation options to guard
483	  against straight line speculation. The kernel image might be slightly
484	  larger.
485
486config X86_CPU_RESCTRL
487	bool "x86 CPU resource control support"
488	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
489	select KERNFS
490	select PROC_CPU_RESCTRL		if PROC_FS
491	help
492	  Enable x86 CPU resource control support.
493
494	  Provide support for the allocation and monitoring of system resources
495	  usage by the CPU.
496
497	  Intel calls this Intel Resource Director Technology
498	  (Intel(R) RDT). More information about RDT can be found in the
499	  Intel x86 Architecture Software Developer Manual.
500
501	  AMD calls this AMD Platform Quality of Service (AMD QoS).
502	  More information about AMD QoS can be found in the AMD64 Technology
503	  Platform Quality of Service Extensions manual.
504
505	  Say N if unsure.
506
507if X86_32
508config X86_BIGSMP
509	bool "Support for big SMP systems with more than 8 CPUs"
510	depends on SMP
511	help
512	  This option is needed for the systems that have more than 8 CPUs.
513
514config X86_EXTENDED_PLATFORM
515	bool "Support for extended (non-PC) x86 platforms"
516	default y
517	help
518	  If you disable this option then the kernel will only support
519	  standard PC platforms. (which covers the vast majority of
520	  systems out there.)
521
522	  If you enable this option then you'll be able to select support
523	  for the following (non-PC) 32 bit x86 platforms:
524		Goldfish (Android emulator)
525		AMD Elan
526		RDC R-321x SoC
527		SGI 320/540 (Visual Workstation)
528		STA2X11-based (e.g. Northville)
529		Moorestown MID devices
530
531	  If you have one of these systems, or if you want to build a
532	  generic distribution kernel, say Y here - otherwise say N.
533endif
534
535if X86_64
536config X86_EXTENDED_PLATFORM
537	bool "Support for extended (non-PC) x86 platforms"
538	default y
539	help
540	  If you disable this option then the kernel will only support
541	  standard PC platforms. (which covers the vast majority of
542	  systems out there.)
543
544	  If you enable this option then you'll be able to select support
545	  for the following (non-PC) 64 bit x86 platforms:
546		Numascale NumaChip
547		ScaleMP vSMP
548		SGI Ultraviolet
549
550	  If you have one of these systems, or if you want to build a
551	  generic distribution kernel, say Y here - otherwise say N.
552endif
553# This is an alphabetically sorted list of 64 bit extended platforms
554# Please maintain the alphabetic order if and when there are additions
555config X86_NUMACHIP
556	bool "Numascale NumaChip"
557	depends on X86_64
558	depends on X86_EXTENDED_PLATFORM
559	depends on NUMA
560	depends on SMP
561	depends on X86_X2APIC
562	depends on PCI_MMCONFIG
563	help
564	  Adds support for Numascale NumaChip large-SMP systems. Needed to
565	  enable more than ~168 cores.
566	  If you don't have one of these, you should say N here.
567
568config X86_VSMP
569	bool "ScaleMP vSMP"
570	select HYPERVISOR_GUEST
571	select PARAVIRT
572	depends on X86_64 && PCI
573	depends on X86_EXTENDED_PLATFORM
574	depends on SMP
575	help
576	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
577	  supposed to run on these EM64T-based machines.  Only choose this option
578	  if you have one of these machines.
579
580config X86_UV
581	bool "SGI Ultraviolet"
582	depends on X86_64
583	depends on X86_EXTENDED_PLATFORM
584	depends on NUMA
585	depends on EFI
586	depends on KEXEC_CORE
587	depends on X86_X2APIC
588	depends on PCI
589	help
590	  This option is needed in order to support SGI Ultraviolet systems.
591	  If you don't have one of these, you should say N here.
592
593# Following is an alphabetically sorted list of 32 bit extended platforms
594# Please maintain the alphabetic order if and when there are additions
595
596config X86_GOLDFISH
597	bool "Goldfish (Virtual Platform)"
598	depends on X86_EXTENDED_PLATFORM
599	help
600	 Enable support for the Goldfish virtual platform used primarily
601	 for Android development. Unless you are building for the Android
602	 Goldfish emulator say N here.
603
604config X86_INTEL_CE
605	bool "CE4100 TV platform"
606	depends on PCI
607	depends on PCI_GODIRECT
608	depends on X86_IO_APIC
609	depends on X86_32
610	depends on X86_EXTENDED_PLATFORM
611	select X86_REBOOTFIXUPS
612	select OF
613	select OF_EARLY_FLATTREE
614	help
615	  Select for the Intel CE media processor (CE4100) SOC.
616	  This option compiles in support for the CE4100 SOC for settop
617	  boxes and media devices.
618
619config X86_INTEL_MID
620	bool "Intel MID platform support"
621	depends on X86_EXTENDED_PLATFORM
622	depends on X86_PLATFORM_DEVICES
623	depends on PCI
624	depends on X86_64 || (PCI_GOANY && X86_32)
625	depends on X86_IO_APIC
626	select I2C
627	select DW_APB_TIMER
628	select INTEL_SCU_PCI
629	help
630	  Select to build a kernel capable of supporting Intel MID (Mobile
631	  Internet Device) platform systems which do not have the PCI legacy
632	  interfaces. If you are building for a PC class system say N here.
633
634	  Intel MID platforms are based on an Intel processor and chipset which
635	  consume less power than most of the x86 derivatives.
636
637config X86_INTEL_QUARK
638	bool "Intel Quark platform support"
639	depends on X86_32
640	depends on X86_EXTENDED_PLATFORM
641	depends on X86_PLATFORM_DEVICES
642	depends on X86_TSC
643	depends on PCI
644	depends on PCI_GOANY
645	depends on X86_IO_APIC
646	select IOSF_MBI
647	select INTEL_IMR
648	select COMMON_CLK
649	help
650	  Select to include support for Quark X1000 SoC.
651	  Say Y here if you have a Quark based system such as the Arduino
652	  compatible Intel Galileo.
653
654config X86_INTEL_LPSS
655	bool "Intel Low Power Subsystem Support"
656	depends on X86 && ACPI && PCI
657	select COMMON_CLK
658	select PINCTRL
659	select IOSF_MBI
660	help
661	  Select to build support for Intel Low Power Subsystem such as
662	  found on Intel Lynxpoint PCH. Selecting this option enables
663	  things like clock tree (common clock framework) and pincontrol
664	  which are needed by the LPSS peripheral drivers.
665
666config X86_AMD_PLATFORM_DEVICE
667	bool "AMD ACPI2Platform devices support"
668	depends on ACPI
669	select COMMON_CLK
670	select PINCTRL
671	help
672	  Select to interpret AMD specific ACPI device to platform device
673	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
674	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
675	  implemented under PINCTRL subsystem.
676
677config IOSF_MBI
678	tristate "Intel SoC IOSF Sideband support for SoC platforms"
679	depends on PCI
680	help
681	  This option enables sideband register access support for Intel SoC
682	  platforms. On these platforms the IOSF sideband is used in lieu of
683	  MSR's for some register accesses, mostly but not limited to thermal
684	  and power. Drivers may query the availability of this device to
685	  determine if they need the sideband in order to work on these
686	  platforms. The sideband is available on the following SoC products.
687	  This list is not meant to be exclusive.
688	   - BayTrail
689	   - Braswell
690	   - Quark
691
692	  You should say Y if you are running a kernel on one of these SoC's.
693
694config IOSF_MBI_DEBUG
695	bool "Enable IOSF sideband access through debugfs"
696	depends on IOSF_MBI && DEBUG_FS
697	help
698	  Select this option to expose the IOSF sideband access registers (MCR,
699	  MDR, MCRX) through debugfs to write and read register information from
700	  different units on the SoC. This is most useful for obtaining device
701	  state information for debug and analysis. As this is a general access
702	  mechanism, users of this option would have specific knowledge of the
703	  device they want to access.
704
705	  If you don't require the option or are in doubt, say N.
706
707config X86_RDC321X
708	bool "RDC R-321x SoC"
709	depends on X86_32
710	depends on X86_EXTENDED_PLATFORM
711	select M486
712	select X86_REBOOTFIXUPS
713	help
714	  This option is needed for RDC R-321x system-on-chip, also known
715	  as R-8610-(G).
716	  If you don't have one of these chips, you should say N here.
717
718config X86_32_NON_STANDARD
719	bool "Support non-standard 32-bit SMP architectures"
720	depends on X86_32 && SMP
721	depends on X86_EXTENDED_PLATFORM
722	help
723	  This option compiles in the bigsmp and STA2X11 default
724	  subarchitectures.  It is intended for a generic binary
725	  kernel. If you select them all, kernel will probe it one by
726	  one and will fallback to default.
727
728# Alphabetically sorted list of Non standard 32 bit platforms
729
730config X86_SUPPORTS_MEMORY_FAILURE
731	def_bool y
732	# MCE code calls memory_failure():
733	depends on X86_MCE
734	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
735	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
736	depends on X86_64 || !SPARSEMEM
737	select ARCH_SUPPORTS_MEMORY_FAILURE
738
739config STA2X11
740	bool "STA2X11 Companion Chip Support"
741	depends on X86_32_NON_STANDARD && PCI
742	select SWIOTLB
743	select MFD_STA2X11
744	select GPIOLIB
745	help
746	  This adds support for boards based on the STA2X11 IO-Hub,
747	  a.k.a. "ConneXt". The chip is used in place of the standard
748	  PC chipset, so all "standard" peripherals are missing. If this
749	  option is selected the kernel will still be able to boot on
750	  standard PC machines.
751
752config X86_32_IRIS
753	tristate "Eurobraille/Iris poweroff module"
754	depends on X86_32
755	help
756	  The Iris machines from EuroBraille do not have APM or ACPI support
757	  to shut themselves down properly.  A special I/O sequence is
758	  needed to do so, which is what this module does at
759	  kernel shutdown.
760
761	  This is only for Iris machines from EuroBraille.
762
763	  If unused, say N.
764
765config SCHED_OMIT_FRAME_POINTER
766	def_bool y
767	prompt "Single-depth WCHAN output"
768	depends on X86
769	help
770	  Calculate simpler /proc/<PID>/wchan values. If this option
771	  is disabled then wchan values will recurse back to the
772	  caller function. This provides more accurate wchan values,
773	  at the expense of slightly more scheduling overhead.
774
775	  If in doubt, say "Y".
776
777menuconfig HYPERVISOR_GUEST
778	bool "Linux guest support"
779	help
780	  Say Y here to enable options for running Linux under various hyper-
781	  visors. This option enables basic hypervisor detection and platform
782	  setup.
783
784	  If you say N, all options in this submenu will be skipped and
785	  disabled, and Linux guest support won't be built in.
786
787if HYPERVISOR_GUEST
788
789config PARAVIRT
790	bool "Enable paravirtualization code"
791	depends on HAVE_STATIC_CALL
792	help
793	  This changes the kernel so it can modify itself when it is run
794	  under a hypervisor, potentially improving performance significantly
795	  over full virtualization.  However, when run without a hypervisor
796	  the kernel is theoretically slower and slightly larger.
797
798config PARAVIRT_XXL
799	bool
800
801config PARAVIRT_DEBUG
802	bool "paravirt-ops debugging"
803	depends on PARAVIRT && DEBUG_KERNEL
804	help
805	  Enable to debug paravirt_ops internals.  Specifically, BUG if
806	  a paravirt_op is missing when it is called.
807
808config PARAVIRT_SPINLOCKS
809	bool "Paravirtualization layer for spinlocks"
810	depends on PARAVIRT && SMP
811	help
812	  Paravirtualized spinlocks allow a pvops backend to replace the
813	  spinlock implementation with something virtualization-friendly
814	  (for example, block the virtual CPU rather than spinning).
815
816	  It has a minimal impact on native kernels and gives a nice performance
817	  benefit on paravirtualized KVM / Xen kernels.
818
819	  If you are unsure how to answer this question, answer Y.
820
821config X86_HV_CALLBACK_VECTOR
822	def_bool n
823
824source "arch/x86/xen/Kconfig"
825
826config KVM_GUEST
827	bool "KVM Guest support (including kvmclock)"
828	depends on PARAVIRT
829	select PARAVIRT_CLOCK
830	select ARCH_CPUIDLE_HALTPOLL
831	select X86_HV_CALLBACK_VECTOR
832	default y
833	help
834	  This option enables various optimizations for running under the KVM
835	  hypervisor. It includes a paravirtualized clock, so that instead
836	  of relying on a PIT (or probably other) emulation by the
837	  underlying device model, the host provides the guest with
838	  timing infrastructure such as time of day, and system time
839
840config ARCH_CPUIDLE_HALTPOLL
841	def_bool n
842	prompt "Disable host haltpoll when loading haltpoll driver"
843	help
844	  If virtualized under KVM, disable host haltpoll.
845
846config PVH
847	bool "Support for running PVH guests"
848	help
849	  This option enables the PVH entry point for guest virtual machines
850	  as specified in the x86/HVM direct boot ABI.
851
852config PARAVIRT_TIME_ACCOUNTING
853	bool "Paravirtual steal time accounting"
854	depends on PARAVIRT
855	help
856	  Select this option to enable fine granularity task steal time
857	  accounting. Time spent executing other tasks in parallel with
858	  the current vCPU is discounted from the vCPU power. To account for
859	  that, there can be a small performance impact.
860
861	  If in doubt, say N here.
862
863config PARAVIRT_CLOCK
864	bool
865
866config JAILHOUSE_GUEST
867	bool "Jailhouse non-root cell support"
868	depends on X86_64 && PCI
869	select X86_PM_TIMER
870	help
871	  This option allows to run Linux as guest in a Jailhouse non-root
872	  cell. You can leave this option disabled if you only want to start
873	  Jailhouse and run Linux afterwards in the root cell.
874
875config ACRN_GUEST
876	bool "ACRN Guest support"
877	depends on X86_64
878	select X86_HV_CALLBACK_VECTOR
879	help
880	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
881	  a flexible, lightweight reference open-source hypervisor, built with
882	  real-time and safety-criticality in mind. It is built for embedded
883	  IOT with small footprint and real-time features. More details can be
884	  found in https://projectacrn.org/.
885
886config INTEL_TDX_GUEST
887	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
888	depends on X86_64 && CPU_SUP_INTEL
889	depends on X86_X2APIC
890	select ARCH_HAS_CC_PLATFORM
891	select X86_MEM_ENCRYPT
892	select X86_MCE
893	help
894	  Support running as a guest under Intel TDX.  Without this support,
895	  the guest kernel can not boot or run under TDX.
896	  TDX includes memory encryption and integrity capabilities
897	  which protect the confidentiality and integrity of guest
898	  memory contents and CPU state. TDX guests are protected from
899	  some attacks from the VMM.
900
901endif #HYPERVISOR_GUEST
902
903source "arch/x86/Kconfig.cpu"
904
905config HPET_TIMER
906	def_bool X86_64
907	prompt "HPET Timer Support" if X86_32
908	help
909	  Use the IA-PC HPET (High Precision Event Timer) to manage
910	  time in preference to the PIT and RTC, if a HPET is
911	  present.
912	  HPET is the next generation timer replacing legacy 8254s.
913	  The HPET provides a stable time base on SMP
914	  systems, unlike the TSC, but it is more expensive to access,
915	  as it is off-chip.  The interface used is documented
916	  in the HPET spec, revision 1.
917
918	  You can safely choose Y here.  However, HPET will only be
919	  activated if the platform and the BIOS support this feature.
920	  Otherwise the 8254 will be used for timing services.
921
922	  Choose N to continue using the legacy 8254 timer.
923
924config HPET_EMULATE_RTC
925	def_bool y
926	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
927
928# Mark as expert because too many people got it wrong.
929# The code disables itself when not needed.
930config DMI
931	default y
932	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
933	bool "Enable DMI scanning" if EXPERT
934	help
935	  Enabled scanning of DMI to identify machine quirks. Say Y
936	  here unless you have verified that your setup is not
937	  affected by entries in the DMI blacklist. Required by PNP
938	  BIOS code.
939
940config GART_IOMMU
941	bool "Old AMD GART IOMMU support"
942	select DMA_OPS
943	select IOMMU_HELPER
944	select SWIOTLB
945	depends on X86_64 && PCI && AMD_NB
946	help
947	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
948	  GART based hardware IOMMUs.
949
950	  The GART supports full DMA access for devices with 32-bit access
951	  limitations, on systems with more than 3 GB. This is usually needed
952	  for USB, sound, many IDE/SATA chipsets and some other devices.
953
954	  Newer systems typically have a modern AMD IOMMU, supported via
955	  the CONFIG_AMD_IOMMU=y config option.
956
957	  In normal configurations this driver is only active when needed:
958	  there's more than 3 GB of memory and the system contains a
959	  32-bit limited device.
960
961	  If unsure, say Y.
962
963config MAXSMP
964	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
965	depends on X86_64 && SMP && DEBUG_KERNEL
966	select CPUMASK_OFFSTACK
967	help
968	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
969	  If unsure, say N.
970
971#
972# The maximum number of CPUs supported:
973#
974# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
975# and which can be configured interactively in the
976# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
977#
978# The ranges are different on 32-bit and 64-bit kernels, depending on
979# hardware capabilities and scalability features of the kernel.
980#
981# ( If MAXSMP is enabled we just use the highest possible value and disable
982#   interactive configuration. )
983#
984
985config NR_CPUS_RANGE_BEGIN
986	int
987	default NR_CPUS_RANGE_END if MAXSMP
988	default    1 if !SMP
989	default    2
990
991config NR_CPUS_RANGE_END
992	int
993	depends on X86_32
994	default   64 if  SMP &&  X86_BIGSMP
995	default    8 if  SMP && !X86_BIGSMP
996	default    1 if !SMP
997
998config NR_CPUS_RANGE_END
999	int
1000	depends on X86_64
1001	default 8192 if  SMP && CPUMASK_OFFSTACK
1002	default  512 if  SMP && !CPUMASK_OFFSTACK
1003	default    1 if !SMP
1004
1005config NR_CPUS_DEFAULT
1006	int
1007	depends on X86_32
1008	default   32 if  X86_BIGSMP
1009	default    8 if  SMP
1010	default    1 if !SMP
1011
1012config NR_CPUS_DEFAULT
1013	int
1014	depends on X86_64
1015	default 8192 if  MAXSMP
1016	default   64 if  SMP
1017	default    1 if !SMP
1018
1019config NR_CPUS
1020	int "Maximum number of CPUs" if SMP && !MAXSMP
1021	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1022	default NR_CPUS_DEFAULT
1023	help
1024	  This allows you to specify the maximum number of CPUs which this
1025	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1026	  supported value is 8192, otherwise the maximum value is 512.  The
1027	  minimum value which makes sense is 2.
1028
1029	  This is purely to save memory: each supported CPU adds about 8KB
1030	  to the kernel image.
1031
1032config SCHED_CLUSTER
1033	bool "Cluster scheduler support"
1034	depends on SMP
1035	default y
1036	help
1037	  Cluster scheduler support improves the CPU scheduler's decision
1038	  making when dealing with machines that have clusters of CPUs.
1039	  Cluster usually means a couple of CPUs which are placed closely
1040	  by sharing mid-level caches, last-level cache tags or internal
1041	  busses.
1042
1043config SCHED_SMT
1044	def_bool y if SMP
1045
1046config SCHED_MC
1047	def_bool y
1048	prompt "Multi-core scheduler support"
1049	depends on SMP
1050	help
1051	  Multi-core scheduler support improves the CPU scheduler's decision
1052	  making when dealing with multi-core CPU chips at a cost of slightly
1053	  increased overhead in some places. If unsure say N here.
1054
1055config SCHED_MC_PRIO
1056	bool "CPU core priorities scheduler support"
1057	depends on SCHED_MC && CPU_SUP_INTEL
1058	select X86_INTEL_PSTATE
1059	select CPU_FREQ
1060	default y
1061	help
1062	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1063	  core ordering determined at manufacturing time, which allows
1064	  certain cores to reach higher turbo frequencies (when running
1065	  single threaded workloads) than others.
1066
1067	  Enabling this kernel feature teaches the scheduler about
1068	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1069	  scheduler's CPU selection logic accordingly, so that higher
1070	  overall system performance can be achieved.
1071
1072	  This feature will have no effect on CPUs without this feature.
1073
1074	  If unsure say Y here.
1075
1076config UP_LATE_INIT
1077	def_bool y
1078	depends on !SMP && X86_LOCAL_APIC
1079
1080config X86_UP_APIC
1081	bool "Local APIC support on uniprocessors" if !PCI_MSI
1082	default PCI_MSI
1083	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1084	help
1085	  A local APIC (Advanced Programmable Interrupt Controller) is an
1086	  integrated interrupt controller in the CPU. If you have a single-CPU
1087	  system which has a processor with a local APIC, you can say Y here to
1088	  enable and use it. If you say Y here even though your machine doesn't
1089	  have a local APIC, then the kernel will still run with no slowdown at
1090	  all. The local APIC supports CPU-generated self-interrupts (timer,
1091	  performance counters), and the NMI watchdog which detects hard
1092	  lockups.
1093
1094config X86_UP_IOAPIC
1095	bool "IO-APIC support on uniprocessors"
1096	depends on X86_UP_APIC
1097	help
1098	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1099	  SMP-capable replacement for PC-style interrupt controllers. Most
1100	  SMP systems and many recent uniprocessor systems have one.
1101
1102	  If you have a single-CPU system with an IO-APIC, you can say Y here
1103	  to use it. If you say Y here even though your machine doesn't have
1104	  an IO-APIC, then the kernel will still run with no slowdown at all.
1105
1106config X86_LOCAL_APIC
1107	def_bool y
1108	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1109	select IRQ_DOMAIN_HIERARCHY
1110	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1111
1112config X86_IO_APIC
1113	def_bool y
1114	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1115
1116config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1117	bool "Reroute for broken boot IRQs"
1118	depends on X86_IO_APIC
1119	help
1120	  This option enables a workaround that fixes a source of
1121	  spurious interrupts. This is recommended when threaded
1122	  interrupt handling is used on systems where the generation of
1123	  superfluous "boot interrupts" cannot be disabled.
1124
1125	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1126	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1127	  kernel does during interrupt handling). On chipsets where this
1128	  boot IRQ generation cannot be disabled, this workaround keeps
1129	  the original IRQ line masked so that only the equivalent "boot
1130	  IRQ" is delivered to the CPUs. The workaround also tells the
1131	  kernel to set up the IRQ handler on the boot IRQ line. In this
1132	  way only one interrupt is delivered to the kernel. Otherwise
1133	  the spurious second interrupt may cause the kernel to bring
1134	  down (vital) interrupt lines.
1135
1136	  Only affects "broken" chipsets. Interrupt sharing may be
1137	  increased on these systems.
1138
1139config X86_MCE
1140	bool "Machine Check / overheating reporting"
1141	select GENERIC_ALLOCATOR
1142	default y
1143	help
1144	  Machine Check support allows the processor to notify the
1145	  kernel if it detects a problem (e.g. overheating, data corruption).
1146	  The action the kernel takes depends on the severity of the problem,
1147	  ranging from warning messages to halting the machine.
1148
1149config X86_MCELOG_LEGACY
1150	bool "Support for deprecated /dev/mcelog character device"
1151	depends on X86_MCE
1152	help
1153	  Enable support for /dev/mcelog which is needed by the old mcelog
1154	  userspace logging daemon. Consider switching to the new generation
1155	  rasdaemon solution.
1156
1157config X86_MCE_INTEL
1158	def_bool y
1159	prompt "Intel MCE features"
1160	depends on X86_MCE && X86_LOCAL_APIC
1161	help
1162	   Additional support for intel specific MCE features such as
1163	   the thermal monitor.
1164
1165config X86_MCE_AMD
1166	def_bool y
1167	prompt "AMD MCE features"
1168	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1169	help
1170	   Additional support for AMD specific MCE features such as
1171	   the DRAM Error Threshold.
1172
1173config X86_ANCIENT_MCE
1174	bool "Support for old Pentium 5 / WinChip machine checks"
1175	depends on X86_32 && X86_MCE
1176	help
1177	  Include support for machine check handling on old Pentium 5 or WinChip
1178	  systems. These typically need to be enabled explicitly on the command
1179	  line.
1180
1181config X86_MCE_THRESHOLD
1182	depends on X86_MCE_AMD || X86_MCE_INTEL
1183	def_bool y
1184
1185config X86_MCE_INJECT
1186	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1187	tristate "Machine check injector support"
1188	help
1189	  Provide support for injecting machine checks for testing purposes.
1190	  If you don't know what a machine check is and you don't do kernel
1191	  QA it is safe to say n.
1192
1193source "arch/x86/events/Kconfig"
1194
1195config X86_LEGACY_VM86
1196	bool "Legacy VM86 support"
1197	depends on X86_32
1198	help
1199	  This option allows user programs to put the CPU into V8086
1200	  mode, which is an 80286-era approximation of 16-bit real mode.
1201
1202	  Some very old versions of X and/or vbetool require this option
1203	  for user mode setting.  Similarly, DOSEMU will use it if
1204	  available to accelerate real mode DOS programs.  However, any
1205	  recent version of DOSEMU, X, or vbetool should be fully
1206	  functional even without kernel VM86 support, as they will all
1207	  fall back to software emulation. Nevertheless, if you are using
1208	  a 16-bit DOS program where 16-bit performance matters, vm86
1209	  mode might be faster than emulation and you might want to
1210	  enable this option.
1211
1212	  Note that any app that works on a 64-bit kernel is unlikely to
1213	  need this option, as 64-bit kernels don't, and can't, support
1214	  V8086 mode. This option is also unrelated to 16-bit protected
1215	  mode and is not needed to run most 16-bit programs under Wine.
1216
1217	  Enabling this option increases the complexity of the kernel
1218	  and slows down exception handling a tiny bit.
1219
1220	  If unsure, say N here.
1221
1222config VM86
1223	bool
1224	default X86_LEGACY_VM86
1225
1226config X86_16BIT
1227	bool "Enable support for 16-bit segments" if EXPERT
1228	default y
1229	depends on MODIFY_LDT_SYSCALL
1230	help
1231	  This option is required by programs like Wine to run 16-bit
1232	  protected mode legacy code on x86 processors.  Disabling
1233	  this option saves about 300 bytes on i386, or around 6K text
1234	  plus 16K runtime memory on x86-64,
1235
1236config X86_ESPFIX32
1237	def_bool y
1238	depends on X86_16BIT && X86_32
1239
1240config X86_ESPFIX64
1241	def_bool y
1242	depends on X86_16BIT && X86_64
1243
1244config X86_VSYSCALL_EMULATION
1245	bool "Enable vsyscall emulation" if EXPERT
1246	default y
1247	depends on X86_64
1248	help
1249	 This enables emulation of the legacy vsyscall page.  Disabling
1250	 it is roughly equivalent to booting with vsyscall=none, except
1251	 that it will also disable the helpful warning if a program
1252	 tries to use a vsyscall.  With this option set to N, offending
1253	 programs will just segfault, citing addresses of the form
1254	 0xffffffffff600?00.
1255
1256	 This option is required by many programs built before 2013, and
1257	 care should be used even with newer programs if set to N.
1258
1259	 Disabling this option saves about 7K of kernel size and
1260	 possibly 4K of additional runtime pagetable memory.
1261
1262config X86_IOPL_IOPERM
1263	bool "IOPERM and IOPL Emulation"
1264	default y
1265	help
1266	  This enables the ioperm() and iopl() syscalls which are necessary
1267	  for legacy applications.
1268
1269	  Legacy IOPL support is an overbroad mechanism which allows user
1270	  space aside of accessing all 65536 I/O ports also to disable
1271	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1272	  capabilities and permission from potentially active security
1273	  modules.
1274
1275	  The emulation restricts the functionality of the syscall to
1276	  only allowing the full range I/O port access, but prevents the
1277	  ability to disable interrupts from user space which would be
1278	  granted if the hardware IOPL mechanism would be used.
1279
1280config TOSHIBA
1281	tristate "Toshiba Laptop support"
1282	depends on X86_32
1283	help
1284	  This adds a driver to safely access the System Management Mode of
1285	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1286	  not work on models with a Phoenix BIOS. The System Management Mode
1287	  is used to set the BIOS and power saving options on Toshiba portables.
1288
1289	  For information on utilities to make use of this driver see the
1290	  Toshiba Linux utilities web site at:
1291	  <http://www.buzzard.org.uk/toshiba/>.
1292
1293	  Say Y if you intend to run this kernel on a Toshiba portable.
1294	  Say N otherwise.
1295
1296config X86_REBOOTFIXUPS
1297	bool "Enable X86 board specific fixups for reboot"
1298	depends on X86_32
1299	help
1300	  This enables chipset and/or board specific fixups to be done
1301	  in order to get reboot to work correctly. This is only needed on
1302	  some combinations of hardware and BIOS. The symptom, for which
1303	  this config is intended, is when reboot ends with a stalled/hung
1304	  system.
1305
1306	  Currently, the only fixup is for the Geode machines using
1307	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1308
1309	  Say Y if you want to enable the fixup. Currently, it's safe to
1310	  enable this option even if you don't need it.
1311	  Say N otherwise.
1312
1313config MICROCODE
1314	bool "CPU microcode loading support"
1315	default y
1316	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1317	help
1318	  If you say Y here, you will be able to update the microcode on
1319	  Intel and AMD processors. The Intel support is for the IA32 family,
1320	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1321	  AMD support is for families 0x10 and later. You will obviously need
1322	  the actual microcode binary data itself which is not shipped with
1323	  the Linux kernel.
1324
1325	  The preferred method to load microcode from a detached initrd is described
1326	  in Documentation/x86/microcode.rst. For that you need to enable
1327	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1328	  initrd for microcode blobs.
1329
1330	  In addition, you can build the microcode into the kernel. For that you
1331	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1332	  config option.
1333
1334config MICROCODE_INTEL
1335	bool "Intel microcode loading support"
1336	depends on CPU_SUP_INTEL && MICROCODE
1337	default MICROCODE
1338	help
1339	  This options enables microcode patch loading support for Intel
1340	  processors.
1341
1342	  For the current Intel microcode data package go to
1343	  <https://downloadcenter.intel.com> and search for
1344	  'Linux Processor Microcode Data File'.
1345
1346config MICROCODE_AMD
1347	bool "AMD microcode loading support"
1348	depends on CPU_SUP_AMD && MICROCODE
1349	help
1350	  If you select this option, microcode patch loading support for AMD
1351	  processors will be enabled.
1352
1353config MICROCODE_OLD_INTERFACE
1354	bool "Ancient loading interface (DEPRECATED)"
1355	default n
1356	depends on MICROCODE
1357	help
1358	  DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1359	  which was used by userspace tools like iucode_tool and microcode.ctl.
1360	  It is inadequate because it runs too late to be able to properly
1361	  load microcode on a machine and it needs special tools. Instead, you
1362	  should've switched to the early loading method with the initrd or
1363	  builtin microcode by now: Documentation/x86/microcode.rst
1364
1365config X86_MSR
1366	tristate "/dev/cpu/*/msr - Model-specific register support"
1367	help
1368	  This device gives privileged processes access to the x86
1369	  Model-Specific Registers (MSRs).  It is a character device with
1370	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1371	  MSR accesses are directed to a specific CPU on multi-processor
1372	  systems.
1373
1374config X86_CPUID
1375	tristate "/dev/cpu/*/cpuid - CPU information support"
1376	help
1377	  This device gives processes access to the x86 CPUID instruction to
1378	  be executed on a specific processor.  It is a character device
1379	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1380	  /dev/cpu/31/cpuid.
1381
1382choice
1383	prompt "High Memory Support"
1384	default HIGHMEM4G
1385	depends on X86_32
1386
1387config NOHIGHMEM
1388	bool "off"
1389	help
1390	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1391	  However, the address space of 32-bit x86 processors is only 4
1392	  Gigabytes large. That means that, if you have a large amount of
1393	  physical memory, not all of it can be "permanently mapped" by the
1394	  kernel. The physical memory that's not permanently mapped is called
1395	  "high memory".
1396
1397	  If you are compiling a kernel which will never run on a machine with
1398	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1399	  choice and suitable for most users). This will result in a "3GB/1GB"
1400	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1401	  space and the remaining part of the 4GB virtual memory space is used
1402	  by the kernel to permanently map as much physical memory as
1403	  possible.
1404
1405	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1406	  answer "4GB" here.
1407
1408	  If more than 4 Gigabytes is used then answer "64GB" here. This
1409	  selection turns Intel PAE (Physical Address Extension) mode on.
1410	  PAE implements 3-level paging on IA32 processors. PAE is fully
1411	  supported by Linux, PAE mode is implemented on all recent Intel
1412	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1413	  then the kernel will not boot on CPUs that don't support PAE!
1414
1415	  The actual amount of total physical memory will either be
1416	  auto detected or can be forced by using a kernel command line option
1417	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1418	  your boot loader (lilo or loadlin) about how to pass options to the
1419	  kernel at boot time.)
1420
1421	  If unsure, say "off".
1422
1423config HIGHMEM4G
1424	bool "4GB"
1425	help
1426	  Select this if you have a 32-bit processor and between 1 and 4
1427	  gigabytes of physical RAM.
1428
1429config HIGHMEM64G
1430	bool "64GB"
1431	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1432	select X86_PAE
1433	help
1434	  Select this if you have a 32-bit processor and more than 4
1435	  gigabytes of physical RAM.
1436
1437endchoice
1438
1439choice
1440	prompt "Memory split" if EXPERT
1441	default VMSPLIT_3G
1442	depends on X86_32
1443	help
1444	  Select the desired split between kernel and user memory.
1445
1446	  If the address range available to the kernel is less than the
1447	  physical memory installed, the remaining memory will be available
1448	  as "high memory". Accessing high memory is a little more costly
1449	  than low memory, as it needs to be mapped into the kernel first.
1450	  Note that increasing the kernel address space limits the range
1451	  available to user programs, making the address space there
1452	  tighter.  Selecting anything other than the default 3G/1G split
1453	  will also likely make your kernel incompatible with binary-only
1454	  kernel modules.
1455
1456	  If you are not absolutely sure what you are doing, leave this
1457	  option alone!
1458
1459	config VMSPLIT_3G
1460		bool "3G/1G user/kernel split"
1461	config VMSPLIT_3G_OPT
1462		depends on !X86_PAE
1463		bool "3G/1G user/kernel split (for full 1G low memory)"
1464	config VMSPLIT_2G
1465		bool "2G/2G user/kernel split"
1466	config VMSPLIT_2G_OPT
1467		depends on !X86_PAE
1468		bool "2G/2G user/kernel split (for full 2G low memory)"
1469	config VMSPLIT_1G
1470		bool "1G/3G user/kernel split"
1471endchoice
1472
1473config PAGE_OFFSET
1474	hex
1475	default 0xB0000000 if VMSPLIT_3G_OPT
1476	default 0x80000000 if VMSPLIT_2G
1477	default 0x78000000 if VMSPLIT_2G_OPT
1478	default 0x40000000 if VMSPLIT_1G
1479	default 0xC0000000
1480	depends on X86_32
1481
1482config HIGHMEM
1483	def_bool y
1484	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1485
1486config X86_PAE
1487	bool "PAE (Physical Address Extension) Support"
1488	depends on X86_32 && !HIGHMEM4G
1489	select PHYS_ADDR_T_64BIT
1490	select SWIOTLB
1491	help
1492	  PAE is required for NX support, and furthermore enables
1493	  larger swapspace support for non-overcommit purposes. It
1494	  has the cost of more pagetable lookup overhead, and also
1495	  consumes more pagetable space per process.
1496
1497config X86_5LEVEL
1498	bool "Enable 5-level page tables support"
1499	default y
1500	select DYNAMIC_MEMORY_LAYOUT
1501	select SPARSEMEM_VMEMMAP
1502	depends on X86_64
1503	help
1504	  5-level paging enables access to larger address space:
1505	  upto 128 PiB of virtual address space and 4 PiB of
1506	  physical address space.
1507
1508	  It will be supported by future Intel CPUs.
1509
1510	  A kernel with the option enabled can be booted on machines that
1511	  support 4- or 5-level paging.
1512
1513	  See Documentation/x86/x86_64/5level-paging.rst for more
1514	  information.
1515
1516	  Say N if unsure.
1517
1518config X86_DIRECT_GBPAGES
1519	def_bool y
1520	depends on X86_64
1521	help
1522	  Certain kernel features effectively disable kernel
1523	  linear 1 GB mappings (even if the CPU otherwise
1524	  supports them), so don't confuse the user by printing
1525	  that we have them enabled.
1526
1527config X86_CPA_STATISTICS
1528	bool "Enable statistic for Change Page Attribute"
1529	depends on DEBUG_FS
1530	help
1531	  Expose statistics about the Change Page Attribute mechanism, which
1532	  helps to determine the effectiveness of preserving large and huge
1533	  page mappings when mapping protections are changed.
1534
1535config X86_MEM_ENCRYPT
1536	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1537	select DYNAMIC_PHYSICAL_MASK
1538	select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1539	def_bool n
1540
1541config AMD_MEM_ENCRYPT
1542	bool "AMD Secure Memory Encryption (SME) support"
1543	depends on X86_64 && CPU_SUP_AMD
1544	select DMA_COHERENT_POOL
1545	select ARCH_USE_MEMREMAP_PROT
1546	select INSTRUCTION_DECODER
1547	select ARCH_HAS_CC_PLATFORM
1548	select X86_MEM_ENCRYPT
1549	help
1550	  Say yes to enable support for the encryption of system memory.
1551	  This requires an AMD processor that supports Secure Memory
1552	  Encryption (SME).
1553
1554config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1555	bool "Activate AMD Secure Memory Encryption (SME) by default"
1556	depends on AMD_MEM_ENCRYPT
1557	help
1558	  Say yes to have system memory encrypted by default if running on
1559	  an AMD processor that supports Secure Memory Encryption (SME).
1560
1561	  If set to Y, then the encryption of system memory can be
1562	  deactivated with the mem_encrypt=off command line option.
1563
1564	  If set to N, then the encryption of system memory can be
1565	  activated with the mem_encrypt=on command line option.
1566
1567# Common NUMA Features
1568config NUMA
1569	bool "NUMA Memory Allocation and Scheduler Support"
1570	depends on SMP
1571	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1572	default y if X86_BIGSMP
1573	select USE_PERCPU_NUMA_NODE_ID
1574	help
1575	  Enable NUMA (Non-Uniform Memory Access) support.
1576
1577	  The kernel will try to allocate memory used by a CPU on the
1578	  local memory controller of the CPU and add some more
1579	  NUMA awareness to the kernel.
1580
1581	  For 64-bit this is recommended if the system is Intel Core i7
1582	  (or later), AMD Opteron, or EM64T NUMA.
1583
1584	  For 32-bit this is only needed if you boot a 32-bit
1585	  kernel on a 64-bit NUMA platform.
1586
1587	  Otherwise, you should say N.
1588
1589config AMD_NUMA
1590	def_bool y
1591	prompt "Old style AMD Opteron NUMA detection"
1592	depends on X86_64 && NUMA && PCI
1593	help
1594	  Enable AMD NUMA node topology detection.  You should say Y here if
1595	  you have a multi processor AMD system. This uses an old method to
1596	  read the NUMA configuration directly from the builtin Northbridge
1597	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1598	  which also takes priority if both are compiled in.
1599
1600config X86_64_ACPI_NUMA
1601	def_bool y
1602	prompt "ACPI NUMA detection"
1603	depends on X86_64 && NUMA && ACPI && PCI
1604	select ACPI_NUMA
1605	help
1606	  Enable ACPI SRAT based node topology detection.
1607
1608config NUMA_EMU
1609	bool "NUMA emulation"
1610	depends on NUMA
1611	help
1612	  Enable NUMA emulation. A flat machine will be split
1613	  into virtual nodes when booted with "numa=fake=N", where N is the
1614	  number of nodes. This is only useful for debugging.
1615
1616config NODES_SHIFT
1617	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1618	range 1 10
1619	default "10" if MAXSMP
1620	default "6" if X86_64
1621	default "3"
1622	depends on NUMA
1623	help
1624	  Specify the maximum number of NUMA Nodes available on the target
1625	  system.  Increases memory reserved to accommodate various tables.
1626
1627config ARCH_FLATMEM_ENABLE
1628	def_bool y
1629	depends on X86_32 && !NUMA
1630
1631config ARCH_SPARSEMEM_ENABLE
1632	def_bool y
1633	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1634	select SPARSEMEM_STATIC if X86_32
1635	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1636
1637config ARCH_SPARSEMEM_DEFAULT
1638	def_bool X86_64 || (NUMA && X86_32)
1639
1640config ARCH_SELECT_MEMORY_MODEL
1641	def_bool y
1642	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1643
1644config ARCH_MEMORY_PROBE
1645	bool "Enable sysfs memory/probe interface"
1646	depends on MEMORY_HOTPLUG
1647	help
1648	  This option enables a sysfs memory/probe interface for testing.
1649	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1650	  If you are unsure how to answer this question, answer N.
1651
1652config ARCH_PROC_KCORE_TEXT
1653	def_bool y
1654	depends on X86_64 && PROC_KCORE
1655
1656config ILLEGAL_POINTER_VALUE
1657	hex
1658	default 0 if X86_32
1659	default 0xdead000000000000 if X86_64
1660
1661config X86_PMEM_LEGACY_DEVICE
1662	bool
1663
1664config X86_PMEM_LEGACY
1665	tristate "Support non-standard NVDIMMs and ADR protected memory"
1666	depends on PHYS_ADDR_T_64BIT
1667	depends on BLK_DEV
1668	select X86_PMEM_LEGACY_DEVICE
1669	select NUMA_KEEP_MEMINFO if NUMA
1670	select LIBNVDIMM
1671	help
1672	  Treat memory marked using the non-standard e820 type of 12 as used
1673	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1674	  The kernel will offer these regions to the 'pmem' driver so
1675	  they can be used for persistent storage.
1676
1677	  Say Y if unsure.
1678
1679config HIGHPTE
1680	bool "Allocate 3rd-level pagetables from highmem"
1681	depends on HIGHMEM
1682	help
1683	  The VM uses one page table entry for each page of physical memory.
1684	  For systems with a lot of RAM, this can be wasteful of precious
1685	  low memory.  Setting this option will put user-space page table
1686	  entries in high memory.
1687
1688config X86_CHECK_BIOS_CORRUPTION
1689	bool "Check for low memory corruption"
1690	help
1691	  Periodically check for memory corruption in low memory, which
1692	  is suspected to be caused by BIOS.  Even when enabled in the
1693	  configuration, it is disabled at runtime.  Enable it by
1694	  setting "memory_corruption_check=1" on the kernel command
1695	  line.  By default it scans the low 64k of memory every 60
1696	  seconds; see the memory_corruption_check_size and
1697	  memory_corruption_check_period parameters in
1698	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1699
1700	  When enabled with the default parameters, this option has
1701	  almost no overhead, as it reserves a relatively small amount
1702	  of memory and scans it infrequently.  It both detects corruption
1703	  and prevents it from affecting the running system.
1704
1705	  It is, however, intended as a diagnostic tool; if repeatable
1706	  BIOS-originated corruption always affects the same memory,
1707	  you can use memmap= to prevent the kernel from using that
1708	  memory.
1709
1710config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1711	bool "Set the default setting of memory_corruption_check"
1712	depends on X86_CHECK_BIOS_CORRUPTION
1713	default y
1714	help
1715	  Set whether the default state of memory_corruption_check is
1716	  on or off.
1717
1718config MATH_EMULATION
1719	bool
1720	depends on MODIFY_LDT_SYSCALL
1721	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1722	help
1723	  Linux can emulate a math coprocessor (used for floating point
1724	  operations) if you don't have one. 486DX and Pentium processors have
1725	  a math coprocessor built in, 486SX and 386 do not, unless you added
1726	  a 487DX or 387, respectively. (The messages during boot time can
1727	  give you some hints here ["man dmesg"].) Everyone needs either a
1728	  coprocessor or this emulation.
1729
1730	  If you don't have a math coprocessor, you need to say Y here; if you
1731	  say Y here even though you have a coprocessor, the coprocessor will
1732	  be used nevertheless. (This behavior can be changed with the kernel
1733	  command line option "no387", which comes handy if your coprocessor
1734	  is broken. Try "man bootparam" or see the documentation of your boot
1735	  loader (lilo or loadlin) about how to pass options to the kernel at
1736	  boot time.) This means that it is a good idea to say Y here if you
1737	  intend to use this kernel on different machines.
1738
1739	  More information about the internals of the Linux math coprocessor
1740	  emulation can be found in <file:arch/x86/math-emu/README>.
1741
1742	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1743	  kernel, it won't hurt.
1744
1745config MTRR
1746	def_bool y
1747	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1748	help
1749	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1750	  the Memory Type Range Registers (MTRRs) may be used to control
1751	  processor access to memory ranges. This is most useful if you have
1752	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1753	  allows bus write transfers to be combined into a larger transfer
1754	  before bursting over the PCI/AGP bus. This can increase performance
1755	  of image write operations 2.5 times or more. Saying Y here creates a
1756	  /proc/mtrr file which may be used to manipulate your processor's
1757	  MTRRs. Typically the X server should use this.
1758
1759	  This code has a reasonably generic interface so that similar
1760	  control registers on other processors can be easily supported
1761	  as well:
1762
1763	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1764	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1765	  these, the ARRs are used to emulate the MTRRs.
1766	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1767	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1768	  write-combining. All of these processors are supported by this code
1769	  and it makes sense to say Y here if you have one of them.
1770
1771	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1772	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1773	  can lead to all sorts of problems, so it's good to say Y here.
1774
1775	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1776	  just add about 9 KB to your kernel.
1777
1778	  See <file:Documentation/x86/mtrr.rst> for more information.
1779
1780config MTRR_SANITIZER
1781	def_bool y
1782	prompt "MTRR cleanup support"
1783	depends on MTRR
1784	help
1785	  Convert MTRR layout from continuous to discrete, so X drivers can
1786	  add writeback entries.
1787
1788	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1789	  The largest mtrr entry size for a continuous block can be set with
1790	  mtrr_chunk_size.
1791
1792	  If unsure, say Y.
1793
1794config MTRR_SANITIZER_ENABLE_DEFAULT
1795	int "MTRR cleanup enable value (0-1)"
1796	range 0 1
1797	default "0"
1798	depends on MTRR_SANITIZER
1799	help
1800	  Enable mtrr cleanup default value
1801
1802config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1803	int "MTRR cleanup spare reg num (0-7)"
1804	range 0 7
1805	default "1"
1806	depends on MTRR_SANITIZER
1807	help
1808	  mtrr cleanup spare entries default, it can be changed via
1809	  mtrr_spare_reg_nr=N on the kernel command line.
1810
1811config X86_PAT
1812	def_bool y
1813	prompt "x86 PAT support" if EXPERT
1814	depends on MTRR
1815	help
1816	  Use PAT attributes to setup page level cache control.
1817
1818	  PATs are the modern equivalents of MTRRs and are much more
1819	  flexible than MTRRs.
1820
1821	  Say N here if you see bootup problems (boot crash, boot hang,
1822	  spontaneous reboots) or a non-working video driver.
1823
1824	  If unsure, say Y.
1825
1826config ARCH_USES_PG_UNCACHED
1827	def_bool y
1828	depends on X86_PAT
1829
1830config ARCH_RANDOM
1831	def_bool y
1832	prompt "x86 architectural random number generator" if EXPERT
1833	help
1834	  Enable the x86 architectural RDRAND instruction
1835	  (Intel Bull Mountain technology) to generate random numbers.
1836	  If supported, this is a high bandwidth, cryptographically
1837	  secure hardware random number generator.
1838
1839config X86_UMIP
1840	def_bool y
1841	prompt "User Mode Instruction Prevention" if EXPERT
1842	help
1843	  User Mode Instruction Prevention (UMIP) is a security feature in
1844	  some x86 processors. If enabled, a general protection fault is
1845	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1846	  executed in user mode. These instructions unnecessarily expose
1847	  information about the hardware state.
1848
1849	  The vast majority of applications do not use these instructions.
1850	  For the very few that do, software emulation is provided in
1851	  specific cases in protected and virtual-8086 modes. Emulated
1852	  results are dummy.
1853
1854config CC_HAS_IBT
1855	# GCC >= 9 and binutils >= 2.29
1856	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1857	# Clang/LLVM >= 14
1858	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1859	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1860	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1861		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1862		  $(as-instr,endbr64)
1863
1864config X86_KERNEL_IBT
1865	prompt "Indirect Branch Tracking"
1866	bool
1867	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1868	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1869	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1870	select OBJTOOL
1871	help
1872	  Build the kernel with support for Indirect Branch Tracking, a
1873	  hardware support course-grain forward-edge Control Flow Integrity
1874	  protection. It enforces that all indirect calls must land on
1875	  an ENDBR instruction, as such, the compiler will instrument the
1876	  code with them to make this happen.
1877
1878	  In addition to building the kernel with IBT, seal all functions that
1879	  are not indirect call targets, avoiding them ever becoming one.
1880
1881	  This requires LTO like objtool runs and will slow down the build. It
1882	  does significantly reduce the number of ENDBR instructions in the
1883	  kernel image.
1884
1885config X86_INTEL_MEMORY_PROTECTION_KEYS
1886	prompt "Memory Protection Keys"
1887	def_bool y
1888	# Note: only available in 64-bit mode
1889	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1890	select ARCH_USES_HIGH_VMA_FLAGS
1891	select ARCH_HAS_PKEYS
1892	help
1893	  Memory Protection Keys provides a mechanism for enforcing
1894	  page-based protections, but without requiring modification of the
1895	  page tables when an application changes protection domains.
1896
1897	  For details, see Documentation/core-api/protection-keys.rst
1898
1899	  If unsure, say y.
1900
1901choice
1902	prompt "TSX enable mode"
1903	depends on CPU_SUP_INTEL
1904	default X86_INTEL_TSX_MODE_OFF
1905	help
1906	  Intel's TSX (Transactional Synchronization Extensions) feature
1907	  allows to optimize locking protocols through lock elision which
1908	  can lead to a noticeable performance boost.
1909
1910	  On the other hand it has been shown that TSX can be exploited
1911	  to form side channel attacks (e.g. TAA) and chances are there
1912	  will be more of those attacks discovered in the future.
1913
1914	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1915	  might override this decision by tsx=on the command line parameter.
1916	  Even with TSX enabled, the kernel will attempt to enable the best
1917	  possible TAA mitigation setting depending on the microcode available
1918	  for the particular machine.
1919
1920	  This option allows to set the default tsx mode between tsx=on, =off
1921	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1922	  details.
1923
1924	  Say off if not sure, auto if TSX is in use but it should be used on safe
1925	  platforms or on if TSX is in use and the security aspect of tsx is not
1926	  relevant.
1927
1928config X86_INTEL_TSX_MODE_OFF
1929	bool "off"
1930	help
1931	  TSX is disabled if possible - equals to tsx=off command line parameter.
1932
1933config X86_INTEL_TSX_MODE_ON
1934	bool "on"
1935	help
1936	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1937	  line parameter.
1938
1939config X86_INTEL_TSX_MODE_AUTO
1940	bool "auto"
1941	help
1942	  TSX is enabled on TSX capable HW that is believed to be safe against
1943	  side channel attacks- equals the tsx=auto command line parameter.
1944endchoice
1945
1946config X86_SGX
1947	bool "Software Guard eXtensions (SGX)"
1948	depends on X86_64 && CPU_SUP_INTEL
1949	depends on CRYPTO=y
1950	depends on CRYPTO_SHA256=y
1951	select SRCU
1952	select MMU_NOTIFIER
1953	select NUMA_KEEP_MEMINFO if NUMA
1954	select XARRAY_MULTI
1955	help
1956	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1957	  that can be used by applications to set aside private regions of code
1958	  and data, referred to as enclaves. An enclave's private memory can
1959	  only be accessed by code running within the enclave. Accesses from
1960	  outside the enclave, including other enclaves, are disallowed by
1961	  hardware.
1962
1963	  If unsure, say N.
1964
1965config EFI
1966	bool "EFI runtime service support"
1967	depends on ACPI
1968	select UCS2_STRING
1969	select EFI_RUNTIME_WRAPPERS
1970	select ARCH_USE_MEMREMAP_PROT
1971	help
1972	  This enables the kernel to use EFI runtime services that are
1973	  available (such as the EFI variable services).
1974
1975	  This option is only useful on systems that have EFI firmware.
1976	  In addition, you should use the latest ELILO loader available
1977	  at <http://elilo.sourceforge.net> in order to take advantage
1978	  of EFI runtime services. However, even with this option, the
1979	  resultant kernel should continue to boot on existing non-EFI
1980	  platforms.
1981
1982config EFI_STUB
1983	bool "EFI stub support"
1984	depends on EFI
1985	depends on $(cc-option,-mabi=ms) || X86_32
1986	select RELOCATABLE
1987	help
1988	  This kernel feature allows a bzImage to be loaded directly
1989	  by EFI firmware without the use of a bootloader.
1990
1991	  See Documentation/admin-guide/efi-stub.rst for more information.
1992
1993config EFI_MIXED
1994	bool "EFI mixed-mode support"
1995	depends on EFI_STUB && X86_64
1996	help
1997	   Enabling this feature allows a 64-bit kernel to be booted
1998	   on a 32-bit firmware, provided that your CPU supports 64-bit
1999	   mode.
2000
2001	   Note that it is not possible to boot a mixed-mode enabled
2002	   kernel via the EFI boot stub - a bootloader that supports
2003	   the EFI handover protocol must be used.
2004
2005	   If unsure, say N.
2006
2007source "kernel/Kconfig.hz"
2008
2009config KEXEC
2010	bool "kexec system call"
2011	select KEXEC_CORE
2012	help
2013	  kexec is a system call that implements the ability to shutdown your
2014	  current kernel, and to start another kernel.  It is like a reboot
2015	  but it is independent of the system firmware.   And like a reboot
2016	  you can start any kernel with it, not just Linux.
2017
2018	  The name comes from the similarity to the exec system call.
2019
2020	  It is an ongoing process to be certain the hardware in a machine
2021	  is properly shutdown, so do not be surprised if this code does not
2022	  initially work for you.  As of this writing the exact hardware
2023	  interface is strongly in flux, so no good recommendation can be
2024	  made.
2025
2026config KEXEC_FILE
2027	bool "kexec file based system call"
2028	select KEXEC_CORE
2029	select BUILD_BIN2C
2030	depends on X86_64
2031	depends on CRYPTO=y
2032	depends on CRYPTO_SHA256=y
2033	help
2034	  This is new version of kexec system call. This system call is
2035	  file based and takes file descriptors as system call argument
2036	  for kernel and initramfs as opposed to list of segments as
2037	  accepted by previous system call.
2038
2039config ARCH_HAS_KEXEC_PURGATORY
2040	def_bool KEXEC_FILE
2041
2042config KEXEC_SIG
2043	bool "Verify kernel signature during kexec_file_load() syscall"
2044	depends on KEXEC_FILE
2045	help
2046
2047	  This option makes the kexec_file_load() syscall check for a valid
2048	  signature of the kernel image.  The image can still be loaded without
2049	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2050	  there's a signature that we can check, then it must be valid.
2051
2052	  In addition to this option, you need to enable signature
2053	  verification for the corresponding kernel image type being
2054	  loaded in order for this to work.
2055
2056config KEXEC_SIG_FORCE
2057	bool "Require a valid signature in kexec_file_load() syscall"
2058	depends on KEXEC_SIG
2059	help
2060	  This option makes kernel signature verification mandatory for
2061	  the kexec_file_load() syscall.
2062
2063config KEXEC_BZIMAGE_VERIFY_SIG
2064	bool "Enable bzImage signature verification support"
2065	depends on KEXEC_SIG
2066	depends on SIGNED_PE_FILE_VERIFICATION
2067	select SYSTEM_TRUSTED_KEYRING
2068	help
2069	  Enable bzImage signature verification support.
2070
2071config CRASH_DUMP
2072	bool "kernel crash dumps"
2073	depends on X86_64 || (X86_32 && HIGHMEM)
2074	help
2075	  Generate crash dump after being started by kexec.
2076	  This should be normally only set in special crash dump kernels
2077	  which are loaded in the main kernel with kexec-tools into
2078	  a specially reserved region and then later executed after
2079	  a crash by kdump/kexec. The crash dump kernel must be compiled
2080	  to a memory address not used by the main kernel or BIOS using
2081	  PHYSICAL_START, or it must be built as a relocatable image
2082	  (CONFIG_RELOCATABLE=y).
2083	  For more details see Documentation/admin-guide/kdump/kdump.rst
2084
2085config KEXEC_JUMP
2086	bool "kexec jump"
2087	depends on KEXEC && HIBERNATION
2088	help
2089	  Jump between original kernel and kexeced kernel and invoke
2090	  code in physical address mode via KEXEC
2091
2092config PHYSICAL_START
2093	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2094	default "0x1000000"
2095	help
2096	  This gives the physical address where the kernel is loaded.
2097
2098	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2099	  bzImage will decompress itself to above physical address and
2100	  run from there. Otherwise, bzImage will run from the address where
2101	  it has been loaded by the boot loader and will ignore above physical
2102	  address.
2103
2104	  In normal kdump cases one does not have to set/change this option
2105	  as now bzImage can be compiled as a completely relocatable image
2106	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2107	  address. This option is mainly useful for the folks who don't want
2108	  to use a bzImage for capturing the crash dump and want to use a
2109	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2110	  to be specifically compiled to run from a specific memory area
2111	  (normally a reserved region) and this option comes handy.
2112
2113	  So if you are using bzImage for capturing the crash dump,
2114	  leave the value here unchanged to 0x1000000 and set
2115	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2116	  for capturing the crash dump change this value to start of
2117	  the reserved region.  In other words, it can be set based on
2118	  the "X" value as specified in the "crashkernel=YM@XM"
2119	  command line boot parameter passed to the panic-ed
2120	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2121	  for more details about crash dumps.
2122
2123	  Usage of bzImage for capturing the crash dump is recommended as
2124	  one does not have to build two kernels. Same kernel can be used
2125	  as production kernel and capture kernel. Above option should have
2126	  gone away after relocatable bzImage support is introduced. But it
2127	  is present because there are users out there who continue to use
2128	  vmlinux for dump capture. This option should go away down the
2129	  line.
2130
2131	  Don't change this unless you know what you are doing.
2132
2133config RELOCATABLE
2134	bool "Build a relocatable kernel"
2135	default y
2136	help
2137	  This builds a kernel image that retains relocation information
2138	  so it can be loaded someplace besides the default 1MB.
2139	  The relocations tend to make the kernel binary about 10% larger,
2140	  but are discarded at runtime.
2141
2142	  One use is for the kexec on panic case where the recovery kernel
2143	  must live at a different physical address than the primary
2144	  kernel.
2145
2146	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2147	  it has been loaded at and the compile time physical address
2148	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2149
2150config RANDOMIZE_BASE
2151	bool "Randomize the address of the kernel image (KASLR)"
2152	depends on RELOCATABLE
2153	default y
2154	help
2155	  In support of Kernel Address Space Layout Randomization (KASLR),
2156	  this randomizes the physical address at which the kernel image
2157	  is decompressed and the virtual address where the kernel
2158	  image is mapped, as a security feature that deters exploit
2159	  attempts relying on knowledge of the location of kernel
2160	  code internals.
2161
2162	  On 64-bit, the kernel physical and virtual addresses are
2163	  randomized separately. The physical address will be anywhere
2164	  between 16MB and the top of physical memory (up to 64TB). The
2165	  virtual address will be randomized from 16MB up to 1GB (9 bits
2166	  of entropy). Note that this also reduces the memory space
2167	  available to kernel modules from 1.5GB to 1GB.
2168
2169	  On 32-bit, the kernel physical and virtual addresses are
2170	  randomized together. They will be randomized from 16MB up to
2171	  512MB (8 bits of entropy).
2172
2173	  Entropy is generated using the RDRAND instruction if it is
2174	  supported. If RDTSC is supported, its value is mixed into
2175	  the entropy pool as well. If neither RDRAND nor RDTSC are
2176	  supported, then entropy is read from the i8254 timer. The
2177	  usable entropy is limited by the kernel being built using
2178	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2179	  minimum of 2MB. As a result, only 10 bits of entropy are
2180	  theoretically possible, but the implementations are further
2181	  limited due to memory layouts.
2182
2183	  If unsure, say Y.
2184
2185# Relocation on x86 needs some additional build support
2186config X86_NEED_RELOCS
2187	def_bool y
2188	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2189
2190config PHYSICAL_ALIGN
2191	hex "Alignment value to which kernel should be aligned"
2192	default "0x200000"
2193	range 0x2000 0x1000000 if X86_32
2194	range 0x200000 0x1000000 if X86_64
2195	help
2196	  This value puts the alignment restrictions on physical address
2197	  where kernel is loaded and run from. Kernel is compiled for an
2198	  address which meets above alignment restriction.
2199
2200	  If bootloader loads the kernel at a non-aligned address and
2201	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2202	  address aligned to above value and run from there.
2203
2204	  If bootloader loads the kernel at a non-aligned address and
2205	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2206	  load address and decompress itself to the address it has been
2207	  compiled for and run from there. The address for which kernel is
2208	  compiled already meets above alignment restrictions. Hence the
2209	  end result is that kernel runs from a physical address meeting
2210	  above alignment restrictions.
2211
2212	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2213	  this value must be a multiple of 0x200000.
2214
2215	  Don't change this unless you know what you are doing.
2216
2217config DYNAMIC_MEMORY_LAYOUT
2218	bool
2219	help
2220	  This option makes base addresses of vmalloc and vmemmap as well as
2221	  __PAGE_OFFSET movable during boot.
2222
2223config RANDOMIZE_MEMORY
2224	bool "Randomize the kernel memory sections"
2225	depends on X86_64
2226	depends on RANDOMIZE_BASE
2227	select DYNAMIC_MEMORY_LAYOUT
2228	default RANDOMIZE_BASE
2229	help
2230	   Randomizes the base virtual address of kernel memory sections
2231	   (physical memory mapping, vmalloc & vmemmap). This security feature
2232	   makes exploits relying on predictable memory locations less reliable.
2233
2234	   The order of allocations remains unchanged. Entropy is generated in
2235	   the same way as RANDOMIZE_BASE. Current implementation in the optimal
2236	   configuration have in average 30,000 different possible virtual
2237	   addresses for each memory section.
2238
2239	   If unsure, say Y.
2240
2241config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2242	hex "Physical memory mapping padding" if EXPERT
2243	depends on RANDOMIZE_MEMORY
2244	default "0xa" if MEMORY_HOTPLUG
2245	default "0x0"
2246	range 0x1 0x40 if MEMORY_HOTPLUG
2247	range 0x0 0x40
2248	help
2249	   Define the padding in terabytes added to the existing physical
2250	   memory size during kernel memory randomization. It is useful
2251	   for memory hotplug support but reduces the entropy available for
2252	   address randomization.
2253
2254	   If unsure, leave at the default value.
2255
2256config HOTPLUG_CPU
2257	def_bool y
2258	depends on SMP
2259
2260config BOOTPARAM_HOTPLUG_CPU0
2261	bool "Set default setting of cpu0_hotpluggable"
2262	depends on HOTPLUG_CPU
2263	help
2264	  Set whether default state of cpu0_hotpluggable is on or off.
2265
2266	  Say Y here to enable CPU0 hotplug by default. If this switch
2267	  is turned on, there is no need to give cpu0_hotplug kernel
2268	  parameter and the CPU0 hotplug feature is enabled by default.
2269
2270	  Please note: there are two known CPU0 dependencies if you want
2271	  to enable the CPU0 hotplug feature either by this switch or by
2272	  cpu0_hotplug kernel parameter.
2273
2274	  First, resume from hibernate or suspend always starts from CPU0.
2275	  So hibernate and suspend are prevented if CPU0 is offline.
2276
2277	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2278	  offline if any interrupt can not migrate out of CPU0. There may
2279	  be other CPU0 dependencies.
2280
2281	  Please make sure the dependencies are under your control before
2282	  you enable this feature.
2283
2284	  Say N if you don't want to enable CPU0 hotplug feature by default.
2285	  You still can enable the CPU0 hotplug feature at boot by kernel
2286	  parameter cpu0_hotplug.
2287
2288config DEBUG_HOTPLUG_CPU0
2289	def_bool n
2290	prompt "Debug CPU0 hotplug"
2291	depends on HOTPLUG_CPU
2292	help
2293	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2294	  soon as possible and boots up userspace with CPU0 offlined. User
2295	  can online CPU0 back after boot time.
2296
2297	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2298	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2299	  compilation or giving cpu0_hotplug kernel parameter at boot.
2300
2301	  If unsure, say N.
2302
2303config COMPAT_VDSO
2304	def_bool n
2305	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2306	depends on COMPAT_32
2307	help
2308	  Certain buggy versions of glibc will crash if they are
2309	  presented with a 32-bit vDSO that is not mapped at the address
2310	  indicated in its segment table.
2311
2312	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2313	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2314	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2315	  the only released version with the bug, but OpenSUSE 9
2316	  contains a buggy "glibc 2.3.2".
2317
2318	  The symptom of the bug is that everything crashes on startup, saying:
2319	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2320
2321	  Saying Y here changes the default value of the vdso32 boot
2322	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2323	  This works around the glibc bug but hurts performance.
2324
2325	  If unsure, say N: if you are compiling your own kernel, you
2326	  are unlikely to be using a buggy version of glibc.
2327
2328choice
2329	prompt "vsyscall table for legacy applications"
2330	depends on X86_64
2331	default LEGACY_VSYSCALL_XONLY
2332	help
2333	  Legacy user code that does not know how to find the vDSO expects
2334	  to be able to issue three syscalls by calling fixed addresses in
2335	  kernel space. Since this location is not randomized with ASLR,
2336	  it can be used to assist security vulnerability exploitation.
2337
2338	  This setting can be changed at boot time via the kernel command
2339	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2340	  is deprecated and can only be enabled using the kernel command
2341	  line.
2342
2343	  On a system with recent enough glibc (2.14 or newer) and no
2344	  static binaries, you can say None without a performance penalty
2345	  to improve security.
2346
2347	  If unsure, select "Emulate execution only".
2348
2349	config LEGACY_VSYSCALL_XONLY
2350		bool "Emulate execution only"
2351		help
2352		  The kernel traps and emulates calls into the fixed vsyscall
2353		  address mapping and does not allow reads.  This
2354		  configuration is recommended when userspace might use the
2355		  legacy vsyscall area but support for legacy binary
2356		  instrumentation of legacy code is not needed.  It mitigates
2357		  certain uses of the vsyscall area as an ASLR-bypassing
2358		  buffer.
2359
2360	config LEGACY_VSYSCALL_NONE
2361		bool "None"
2362		help
2363		  There will be no vsyscall mapping at all. This will
2364		  eliminate any risk of ASLR bypass due to the vsyscall
2365		  fixed address mapping. Attempts to use the vsyscalls
2366		  will be reported to dmesg, so that either old or
2367		  malicious userspace programs can be identified.
2368
2369endchoice
2370
2371config CMDLINE_BOOL
2372	bool "Built-in kernel command line"
2373	help
2374	  Allow for specifying boot arguments to the kernel at
2375	  build time.  On some systems (e.g. embedded ones), it is
2376	  necessary or convenient to provide some or all of the
2377	  kernel boot arguments with the kernel itself (that is,
2378	  to not rely on the boot loader to provide them.)
2379
2380	  To compile command line arguments into the kernel,
2381	  set this option to 'Y', then fill in the
2382	  boot arguments in CONFIG_CMDLINE.
2383
2384	  Systems with fully functional boot loaders (i.e. non-embedded)
2385	  should leave this option set to 'N'.
2386
2387config CMDLINE
2388	string "Built-in kernel command string"
2389	depends on CMDLINE_BOOL
2390	default ""
2391	help
2392	  Enter arguments here that should be compiled into the kernel
2393	  image and used at boot time.  If the boot loader provides a
2394	  command line at boot time, it is appended to this string to
2395	  form the full kernel command line, when the system boots.
2396
2397	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2398	  change this behavior.
2399
2400	  In most cases, the command line (whether built-in or provided
2401	  by the boot loader) should specify the device for the root
2402	  file system.
2403
2404config CMDLINE_OVERRIDE
2405	bool "Built-in command line overrides boot loader arguments"
2406	depends on CMDLINE_BOOL && CMDLINE != ""
2407	help
2408	  Set this option to 'Y' to have the kernel ignore the boot loader
2409	  command line, and use ONLY the built-in command line.
2410
2411	  This is used to work around broken boot loaders.  This should
2412	  be set to 'N' under normal conditions.
2413
2414config MODIFY_LDT_SYSCALL
2415	bool "Enable the LDT (local descriptor table)" if EXPERT
2416	default y
2417	help
2418	  Linux can allow user programs to install a per-process x86
2419	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2420	  call.  This is required to run 16-bit or segmented code such as
2421	  DOSEMU or some Wine programs.  It is also used by some very old
2422	  threading libraries.
2423
2424	  Enabling this feature adds a small amount of overhead to
2425	  context switches and increases the low-level kernel attack
2426	  surface.  Disabling it removes the modify_ldt(2) system call.
2427
2428	  Saying 'N' here may make sense for embedded or server kernels.
2429
2430config STRICT_SIGALTSTACK_SIZE
2431	bool "Enforce strict size checking for sigaltstack"
2432	depends on DYNAMIC_SIGFRAME
2433	help
2434	  For historical reasons MINSIGSTKSZ is a constant which became
2435	  already too small with AVX512 support. Add a mechanism to
2436	  enforce strict checking of the sigaltstack size against the
2437	  real size of the FPU frame. This option enables the check
2438	  by default. It can also be controlled via the kernel command
2439	  line option 'strict_sas_size' independent of this config
2440	  switch. Enabling it might break existing applications which
2441	  allocate a too small sigaltstack but 'work' because they
2442	  never get a signal delivered.
2443
2444	  Say 'N' unless you want to really enforce this check.
2445
2446source "kernel/livepatch/Kconfig"
2447
2448endmenu
2449
2450config ARCH_HAS_ADD_PAGES
2451	def_bool y
2452	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2453
2454config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2455	def_bool y
2456
2457menu "Power management and ACPI options"
2458
2459config ARCH_HIBERNATION_HEADER
2460	def_bool y
2461	depends on HIBERNATION
2462
2463source "kernel/power/Kconfig"
2464
2465source "drivers/acpi/Kconfig"
2466
2467config X86_APM_BOOT
2468	def_bool y
2469	depends on APM
2470
2471menuconfig APM
2472	tristate "APM (Advanced Power Management) BIOS support"
2473	depends on X86_32 && PM_SLEEP
2474	help
2475	  APM is a BIOS specification for saving power using several different
2476	  techniques. This is mostly useful for battery powered laptops with
2477	  APM compliant BIOSes. If you say Y here, the system time will be
2478	  reset after a RESUME operation, the /proc/apm device will provide
2479	  battery status information, and user-space programs will receive
2480	  notification of APM "events" (e.g. battery status change).
2481
2482	  If you select "Y" here, you can disable actual use of the APM
2483	  BIOS by passing the "apm=off" option to the kernel at boot time.
2484
2485	  Note that the APM support is almost completely disabled for
2486	  machines with more than one CPU.
2487
2488	  In order to use APM, you will need supporting software. For location
2489	  and more information, read <file:Documentation/power/apm-acpi.rst>
2490	  and the Battery Powered Linux mini-HOWTO, available from
2491	  <http://www.tldp.org/docs.html#howto>.
2492
2493	  This driver does not spin down disk drives (see the hdparm(8)
2494	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2495	  VESA-compliant "green" monitors.
2496
2497	  This driver does not support the TI 4000M TravelMate and the ACER
2498	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2499	  desktop machines also don't have compliant BIOSes, and this driver
2500	  may cause those machines to panic during the boot phase.
2501
2502	  Generally, if you don't have a battery in your machine, there isn't
2503	  much point in using this driver and you should say N. If you get
2504	  random kernel OOPSes or reboots that don't seem to be related to
2505	  anything, try disabling/enabling this option (or disabling/enabling
2506	  APM in your BIOS).
2507
2508	  Some other things you should try when experiencing seemingly random,
2509	  "weird" problems:
2510
2511	  1) make sure that you have enough swap space and that it is
2512	  enabled.
2513	  2) pass the "no-hlt" option to the kernel
2514	  3) switch on floating point emulation in the kernel and pass
2515	  the "no387" option to the kernel
2516	  4) pass the "floppy=nodma" option to the kernel
2517	  5) pass the "mem=4M" option to the kernel (thereby disabling
2518	  all but the first 4 MB of RAM)
2519	  6) make sure that the CPU is not over clocked.
2520	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2521	  8) disable the cache from your BIOS settings
2522	  9) install a fan for the video card or exchange video RAM
2523	  10) install a better fan for the CPU
2524	  11) exchange RAM chips
2525	  12) exchange the motherboard.
2526
2527	  To compile this driver as a module, choose M here: the
2528	  module will be called apm.
2529
2530if APM
2531
2532config APM_IGNORE_USER_SUSPEND
2533	bool "Ignore USER SUSPEND"
2534	help
2535	  This option will ignore USER SUSPEND requests. On machines with a
2536	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2537	  series notebooks, it is necessary to say Y because of a BIOS bug.
2538
2539config APM_DO_ENABLE
2540	bool "Enable PM at boot time"
2541	help
2542	  Enable APM features at boot time. From page 36 of the APM BIOS
2543	  specification: "When disabled, the APM BIOS does not automatically
2544	  power manage devices, enter the Standby State, enter the Suspend
2545	  State, or take power saving steps in response to CPU Idle calls."
2546	  This driver will make CPU Idle calls when Linux is idle (unless this
2547	  feature is turned off -- see "Do CPU IDLE calls", below). This
2548	  should always save battery power, but more complicated APM features
2549	  will be dependent on your BIOS implementation. You may need to turn
2550	  this option off if your computer hangs at boot time when using APM
2551	  support, or if it beeps continuously instead of suspending. Turn
2552	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2553	  T400CDT. This is off by default since most machines do fine without
2554	  this feature.
2555
2556config APM_CPU_IDLE
2557	depends on CPU_IDLE
2558	bool "Make CPU Idle calls when idle"
2559	help
2560	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2561	  On some machines, this can activate improved power savings, such as
2562	  a slowed CPU clock rate, when the machine is idle. These idle calls
2563	  are made after the idle loop has run for some length of time (e.g.,
2564	  333 mS). On some machines, this will cause a hang at boot time or
2565	  whenever the CPU becomes idle. (On machines with more than one CPU,
2566	  this option does nothing.)
2567
2568config APM_DISPLAY_BLANK
2569	bool "Enable console blanking using APM"
2570	help
2571	  Enable console blanking using the APM. Some laptops can use this to
2572	  turn off the LCD backlight when the screen blanker of the Linux
2573	  virtual console blanks the screen. Note that this is only used by
2574	  the virtual console screen blanker, and won't turn off the backlight
2575	  when using the X Window system. This also doesn't have anything to
2576	  do with your VESA-compliant power-saving monitor. Further, this
2577	  option doesn't work for all laptops -- it might not turn off your
2578	  backlight at all, or it might print a lot of errors to the console,
2579	  especially if you are using gpm.
2580
2581config APM_ALLOW_INTS
2582	bool "Allow interrupts during APM BIOS calls"
2583	help
2584	  Normally we disable external interrupts while we are making calls to
2585	  the APM BIOS as a measure to lessen the effects of a badly behaving
2586	  BIOS implementation.  The BIOS should reenable interrupts if it
2587	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2588	  many of the newer IBM Thinkpads.  If you experience hangs when you
2589	  suspend, try setting this to Y.  Otherwise, say N.
2590
2591endif # APM
2592
2593source "drivers/cpufreq/Kconfig"
2594
2595source "drivers/cpuidle/Kconfig"
2596
2597source "drivers/idle/Kconfig"
2598
2599endmenu
2600
2601
2602menu "Bus options (PCI etc.)"
2603
2604choice
2605	prompt "PCI access mode"
2606	depends on X86_32 && PCI
2607	default PCI_GOANY
2608	help
2609	  On PCI systems, the BIOS can be used to detect the PCI devices and
2610	  determine their configuration. However, some old PCI motherboards
2611	  have BIOS bugs and may crash if this is done. Also, some embedded
2612	  PCI-based systems don't have any BIOS at all. Linux can also try to
2613	  detect the PCI hardware directly without using the BIOS.
2614
2615	  With this option, you can specify how Linux should detect the
2616	  PCI devices. If you choose "BIOS", the BIOS will be used,
2617	  if you choose "Direct", the BIOS won't be used, and if you
2618	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2619	  If you choose "Any", the kernel will try MMCONFIG, then the
2620	  direct access method and falls back to the BIOS if that doesn't
2621	  work. If unsure, go with the default, which is "Any".
2622
2623config PCI_GOBIOS
2624	bool "BIOS"
2625
2626config PCI_GOMMCONFIG
2627	bool "MMConfig"
2628
2629config PCI_GODIRECT
2630	bool "Direct"
2631
2632config PCI_GOOLPC
2633	bool "OLPC XO-1"
2634	depends on OLPC
2635
2636config PCI_GOANY
2637	bool "Any"
2638
2639endchoice
2640
2641config PCI_BIOS
2642	def_bool y
2643	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2644
2645# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2646config PCI_DIRECT
2647	def_bool y
2648	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2649
2650config PCI_MMCONFIG
2651	bool "Support mmconfig PCI config space access" if X86_64
2652	default y
2653	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2654	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2655
2656config PCI_OLPC
2657	def_bool y
2658	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2659
2660config PCI_XEN
2661	def_bool y
2662	depends on PCI && XEN
2663
2664config MMCONF_FAM10H
2665	def_bool y
2666	depends on X86_64 && PCI_MMCONFIG && ACPI
2667
2668config PCI_CNB20LE_QUIRK
2669	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2670	depends on PCI
2671	help
2672	  Read the PCI windows out of the CNB20LE host bridge. This allows
2673	  PCI hotplug to work on systems with the CNB20LE chipset which do
2674	  not have ACPI.
2675
2676	  There's no public spec for this chipset, and this functionality
2677	  is known to be incomplete.
2678
2679	  You should say N unless you know you need this.
2680
2681config ISA_BUS
2682	bool "ISA bus support on modern systems" if EXPERT
2683	help
2684	  Expose ISA bus device drivers and options available for selection and
2685	  configuration. Enable this option if your target machine has an ISA
2686	  bus. ISA is an older system, displaced by PCI and newer bus
2687	  architectures -- if your target machine is modern, it probably does
2688	  not have an ISA bus.
2689
2690	  If unsure, say N.
2691
2692# x86_64 have no ISA slots, but can have ISA-style DMA.
2693config ISA_DMA_API
2694	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2695	default y
2696	help
2697	  Enables ISA-style DMA support for devices requiring such controllers.
2698	  If unsure, say Y.
2699
2700if X86_32
2701
2702config ISA
2703	bool "ISA support"
2704	help
2705	  Find out whether you have ISA slots on your motherboard.  ISA is the
2706	  name of a bus system, i.e. the way the CPU talks to the other stuff
2707	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2708	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2709	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2710
2711config SCx200
2712	tristate "NatSemi SCx200 support"
2713	help
2714	  This provides basic support for National Semiconductor's
2715	  (now AMD's) Geode processors.  The driver probes for the
2716	  PCI-IDs of several on-chip devices, so its a good dependency
2717	  for other scx200_* drivers.
2718
2719	  If compiled as a module, the driver is named scx200.
2720
2721config SCx200HR_TIMER
2722	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2723	depends on SCx200
2724	default y
2725	help
2726	  This driver provides a clocksource built upon the on-chip
2727	  27MHz high-resolution timer.  Its also a workaround for
2728	  NSC Geode SC-1100's buggy TSC, which loses time when the
2729	  processor goes idle (as is done by the scheduler).  The
2730	  other workaround is idle=poll boot option.
2731
2732config OLPC
2733	bool "One Laptop Per Child support"
2734	depends on !X86_PAE
2735	select GPIOLIB
2736	select OF
2737	select OF_PROMTREE
2738	select IRQ_DOMAIN
2739	select OLPC_EC
2740	help
2741	  Add support for detecting the unique features of the OLPC
2742	  XO hardware.
2743
2744config OLPC_XO1_PM
2745	bool "OLPC XO-1 Power Management"
2746	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2747	help
2748	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2749
2750config OLPC_XO1_RTC
2751	bool "OLPC XO-1 Real Time Clock"
2752	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2753	help
2754	  Add support for the XO-1 real time clock, which can be used as a
2755	  programmable wakeup source.
2756
2757config OLPC_XO1_SCI
2758	bool "OLPC XO-1 SCI extras"
2759	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2760	depends on INPUT=y
2761	select POWER_SUPPLY
2762	help
2763	  Add support for SCI-based features of the OLPC XO-1 laptop:
2764	   - EC-driven system wakeups
2765	   - Power button
2766	   - Ebook switch
2767	   - Lid switch
2768	   - AC adapter status updates
2769	   - Battery status updates
2770
2771config OLPC_XO15_SCI
2772	bool "OLPC XO-1.5 SCI extras"
2773	depends on OLPC && ACPI
2774	select POWER_SUPPLY
2775	help
2776	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2777	   - EC-driven system wakeups
2778	   - AC adapter status updates
2779	   - Battery status updates
2780
2781config ALIX
2782	bool "PCEngines ALIX System Support (LED setup)"
2783	select GPIOLIB
2784	help
2785	  This option enables system support for the PCEngines ALIX.
2786	  At present this just sets up LEDs for GPIO control on
2787	  ALIX2/3/6 boards.  However, other system specific setup should
2788	  get added here.
2789
2790	  Note: You must still enable the drivers for GPIO and LED support
2791	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2792
2793	  Note: You have to set alix.force=1 for boards with Award BIOS.
2794
2795config NET5501
2796	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2797	select GPIOLIB
2798	help
2799	  This option enables system support for the Soekris Engineering net5501.
2800
2801config GEOS
2802	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2803	select GPIOLIB
2804	depends on DMI
2805	help
2806	  This option enables system support for the Traverse Technologies GEOS.
2807
2808config TS5500
2809	bool "Technologic Systems TS-5500 platform support"
2810	depends on MELAN
2811	select CHECK_SIGNATURE
2812	select NEW_LEDS
2813	select LEDS_CLASS
2814	help
2815	  This option enables system support for the Technologic Systems TS-5500.
2816
2817endif # X86_32
2818
2819config AMD_NB
2820	def_bool y
2821	depends on CPU_SUP_AMD && PCI
2822
2823endmenu
2824
2825
2826menu "Binary Emulations"
2827
2828config IA32_EMULATION
2829	bool "IA32 Emulation"
2830	depends on X86_64
2831	select ARCH_WANT_OLD_COMPAT_IPC
2832	select BINFMT_ELF
2833	select COMPAT_OLD_SIGACTION
2834	help
2835	  Include code to run legacy 32-bit programs under a
2836	  64-bit kernel. You should likely turn this on, unless you're
2837	  100% sure that you don't have any 32-bit programs left.
2838
2839config X86_X32_ABI
2840	bool "x32 ABI for 64-bit mode"
2841	depends on X86_64
2842	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2843	# compressed debug sections to x86_x32 properly:
2844	# https://github.com/ClangBuiltLinux/linux/issues/514
2845	# https://github.com/ClangBuiltLinux/linux/issues/1141
2846	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2847	help
2848	  Include code to run binaries for the x32 native 32-bit ABI
2849	  for 64-bit processors.  An x32 process gets access to the
2850	  full 64-bit register file and wide data path while leaving
2851	  pointers at 32 bits for smaller memory footprint.
2852
2853config COMPAT_32
2854	def_bool y
2855	depends on IA32_EMULATION || X86_32
2856	select HAVE_UID16
2857	select OLD_SIGSUSPEND3
2858
2859config COMPAT
2860	def_bool y
2861	depends on IA32_EMULATION || X86_X32_ABI
2862
2863if COMPAT
2864config COMPAT_FOR_U64_ALIGNMENT
2865	def_bool y
2866
2867config SYSVIPC_COMPAT
2868	def_bool y
2869	depends on SYSVIPC
2870endif
2871
2872endmenu
2873
2874
2875config HAVE_ATOMIC_IOMAP
2876	def_bool y
2877	depends on X86_32
2878
2879source "arch/x86/kvm/Kconfig"
2880
2881source "arch/x86/Kconfig.assembler"
2882