xref: /linux/arch/x86/Kconfig (revision 06b9cce42634a50f2840777a66553b02320db5ef)
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_DEBUG_VIRTUAL
73	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
74	select ARCH_HAS_DEVMEM_IS_ALLOWED
75	select ARCH_HAS_EARLY_DEBUG		if KGDB
76	select ARCH_HAS_ELF_RANDOMIZE
77	select ARCH_HAS_FAST_MULTIPLIER
78	select ARCH_HAS_FILTER_PGPROT
79	select ARCH_HAS_FORTIFY_SOURCE
80	select ARCH_HAS_GCOV_PROFILE_ALL
81	select ARCH_HAS_KCOV			if X86_64
82	select ARCH_HAS_MEM_ENCRYPT
83	select ARCH_HAS_MEMBARRIER_SYNC_CORE
84	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85	select ARCH_HAS_PMEM_API		if X86_64
86	select ARCH_HAS_PTE_DEVMAP		if X86_64
87	select ARCH_HAS_PTE_SPECIAL
88	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
89	select ARCH_HAS_COPY_MC			if X86_64
90	select ARCH_HAS_SET_MEMORY
91	select ARCH_HAS_SET_DIRECT_MAP
92	select ARCH_HAS_STRICT_KERNEL_RWX
93	select ARCH_HAS_STRICT_MODULE_RWX
94	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95	select ARCH_HAS_SYSCALL_WRAPPER
96	select ARCH_HAS_UBSAN_SANITIZE_ALL
97	select ARCH_HAS_DEBUG_WX
98	select ARCH_HAS_ZONE_DMA_SET if EXPERT
99	select ARCH_HAVE_NMI_SAFE_CMPXCHG
100	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
101	select ARCH_MIGHT_HAVE_PC_PARPORT
102	select ARCH_MIGHT_HAVE_PC_SERIO
103	select ARCH_STACKWALK
104	select ARCH_SUPPORTS_ACPI
105	select ARCH_SUPPORTS_ATOMIC_RMW
106	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
107	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
108	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
109	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
110	select ARCH_SUPPORTS_LTO_CLANG
111	select ARCH_SUPPORTS_LTO_CLANG_THIN
112	select ARCH_USE_BUILTIN_BSWAP
113	select ARCH_USE_MEMTEST
114	select ARCH_USE_QUEUED_RWLOCKS
115	select ARCH_USE_QUEUED_SPINLOCKS
116	select ARCH_USE_SYM_ANNOTATIONS
117	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
118	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
119	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
120	select ARCH_WANTS_NO_INSTR
121	select ARCH_WANT_HUGE_PMD_SHARE
122	select ARCH_WANT_LD_ORPHAN_WARN
123	select ARCH_WANTS_THP_SWAP		if X86_64
124	select ARCH_HAS_PARANOID_L1D_FLUSH
125	select BUILDTIME_TABLE_SORT
126	select CLKEVT_I8253
127	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
128	select CLOCKSOURCE_WATCHDOG
129	select DCACHE_WORD_ACCESS
130	select DYNAMIC_SIGFRAME
131	select EDAC_ATOMIC_SCRUB
132	select EDAC_SUPPORT
133	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
134	select GENERIC_CLOCKEVENTS_MIN_ADJUST
135	select GENERIC_CMOS_UPDATE
136	select GENERIC_CPU_AUTOPROBE
137	select GENERIC_CPU_VULNERABILITIES
138	select GENERIC_EARLY_IOREMAP
139	select GENERIC_ENTRY
140	select GENERIC_IOMAP
141	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
142	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
143	select GENERIC_IRQ_MIGRATION		if SMP
144	select GENERIC_IRQ_PROBE
145	select GENERIC_IRQ_RESERVATION_MODE
146	select GENERIC_IRQ_SHOW
147	select GENERIC_PENDING_IRQ		if SMP
148	select GENERIC_PTDUMP
149	select GENERIC_SMP_IDLE_THREAD
150	select GENERIC_TIME_VSYSCALL
151	select GENERIC_GETTIMEOFDAY
152	select GENERIC_VDSO_TIME_NS
153	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
154	select HARDIRQS_SW_RESEND
155	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
156	select HAVE_ACPI_APEI			if ACPI
157	select HAVE_ACPI_APEI_NMI		if ACPI
158	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
159	select HAVE_ARCH_AUDITSYSCALL
160	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
161	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
162	select HAVE_ARCH_JUMP_LABEL
163	select HAVE_ARCH_JUMP_LABEL_RELATIVE
164	select HAVE_ARCH_KASAN			if X86_64
165	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
166	select HAVE_ARCH_KFENCE
167	select HAVE_ARCH_KGDB
168	select HAVE_ARCH_MMAP_RND_BITS		if MMU
169	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
170	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
171	select HAVE_ARCH_PREL32_RELOCATIONS
172	select HAVE_ARCH_SECCOMP_FILTER
173	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
174	select HAVE_ARCH_STACKLEAK
175	select HAVE_ARCH_TRACEHOOK
176	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
177	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
178	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
179	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
180	select HAVE_ARCH_VMAP_STACK		if X86_64
181	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
182	select HAVE_ARCH_WITHIN_STACK_FRAMES
183	select HAVE_ASM_MODVERSIONS
184	select HAVE_CMPXCHG_DOUBLE
185	select HAVE_CMPXCHG_LOCAL
186	select HAVE_CONTEXT_TRACKING		if X86_64
187	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
188	select HAVE_C_RECORDMCOUNT
189	select HAVE_OBJTOOL_MCOUNT		if STACK_VALIDATION
190	select HAVE_BUILDTIME_MCOUNT_SORT
191	select HAVE_DEBUG_KMEMLEAK
192	select HAVE_DMA_CONTIGUOUS
193	select HAVE_DYNAMIC_FTRACE
194	select HAVE_DYNAMIC_FTRACE_WITH_REGS
195	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
196	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
197	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
198	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
199	select HAVE_EBPF_JIT
200	select HAVE_EFFICIENT_UNALIGNED_ACCESS
201	select HAVE_EISA
202	select HAVE_EXIT_THREAD
203	select HAVE_FAST_GUP
204	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
205	select HAVE_FTRACE_MCOUNT_RECORD
206	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
207	select HAVE_FUNCTION_TRACER
208	select HAVE_GCC_PLUGINS
209	select HAVE_HW_BREAKPOINT
210	select HAVE_IOREMAP_PROT
211	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
212	select HAVE_IRQ_TIME_ACCOUNTING
213	select HAVE_KERNEL_BZIP2
214	select HAVE_KERNEL_GZIP
215	select HAVE_KERNEL_LZ4
216	select HAVE_KERNEL_LZMA
217	select HAVE_KERNEL_LZO
218	select HAVE_KERNEL_XZ
219	select HAVE_KERNEL_ZSTD
220	select HAVE_KPROBES
221	select HAVE_KPROBES_ON_FTRACE
222	select HAVE_FUNCTION_ERROR_INJECTION
223	select HAVE_KRETPROBES
224	select HAVE_KVM
225	select HAVE_LIVEPATCH			if X86_64
226	select HAVE_MIXED_BREAKPOINTS_REGS
227	select HAVE_MOD_ARCH_SPECIFIC
228	select HAVE_MOVE_PMD
229	select HAVE_MOVE_PUD
230	select HAVE_NMI
231	select HAVE_OPTPROBES
232	select HAVE_PCSPKR_PLATFORM
233	select HAVE_PERF_EVENTS
234	select HAVE_PERF_EVENTS_NMI
235	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
236	select HAVE_PCI
237	select HAVE_PERF_REGS
238	select HAVE_PERF_USER_STACK_DUMP
239	select MMU_GATHER_RCU_TABLE_FREE		if PARAVIRT
240	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
241	select HAVE_REGS_AND_STACK_ACCESS_API
242	select HAVE_RELIABLE_STACKTRACE		if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
243	select HAVE_FUNCTION_ARG_ACCESS_API
244	select HAVE_SETUP_PER_CPU_AREA
245	select HAVE_SOFTIRQ_ON_OWN_STACK
246	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
247	select HAVE_STACK_VALIDATION		if X86_64
248	select HAVE_STATIC_CALL
249	select HAVE_STATIC_CALL_INLINE		if HAVE_STACK_VALIDATION
250	select HAVE_PREEMPT_DYNAMIC
251	select HAVE_RSEQ
252	select HAVE_SYSCALL_TRACEPOINTS
253	select HAVE_UNSTABLE_SCHED_CLOCK
254	select HAVE_USER_RETURN_NOTIFIER
255	select HAVE_GENERIC_VDSO
256	select HOTPLUG_SMT			if SMP
257	select IRQ_FORCED_THREADING
258	select NEED_PER_CPU_EMBED_FIRST_CHUNK
259	select NEED_PER_CPU_PAGE_FIRST_CHUNK
260	select NEED_SG_DMA_LENGTH
261	select PCI_DOMAINS			if PCI
262	select PCI_LOCKLESS_CONFIG		if PCI
263	select PERF_EVENTS
264	select RTC_LIB
265	select RTC_MC146818_LIB
266	select SPARSE_IRQ
267	select SRCU
268	select STACK_VALIDATION			if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
269	select SYSCTL_EXCEPTION_TRACE
270	select THREAD_INFO_IN_TASK
271	select TRACE_IRQFLAGS_SUPPORT
272	select USER_STACKTRACE_SUPPORT
273	select VIRT_TO_BUS
274	select HAVE_ARCH_KCSAN			if X86_64
275	select X86_FEATURE_NAMES		if PROC_FS
276	select PROC_PID_ARCH_STATUS		if PROC_FS
277	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
278	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
279
280config INSTRUCTION_DECODER
281	def_bool y
282	depends on KPROBES || PERF_EVENTS || UPROBES
283
284config OUTPUT_FORMAT
285	string
286	default "elf32-i386" if X86_32
287	default "elf64-x86-64" if X86_64
288
289config LOCKDEP_SUPPORT
290	def_bool y
291
292config STACKTRACE_SUPPORT
293	def_bool y
294
295config MMU
296	def_bool y
297
298config ARCH_MMAP_RND_BITS_MIN
299	default 28 if 64BIT
300	default 8
301
302config ARCH_MMAP_RND_BITS_MAX
303	default 32 if 64BIT
304	default 16
305
306config ARCH_MMAP_RND_COMPAT_BITS_MIN
307	default 8
308
309config ARCH_MMAP_RND_COMPAT_BITS_MAX
310	default 16
311
312config SBUS
313	bool
314
315config GENERIC_ISA_DMA
316	def_bool y
317	depends on ISA_DMA_API
318
319config GENERIC_BUG
320	def_bool y
321	depends on BUG
322	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
323
324config GENERIC_BUG_RELATIVE_POINTERS
325	bool
326
327config ARCH_MAY_HAVE_PC_FDC
328	def_bool y
329	depends on ISA_DMA_API
330
331config GENERIC_CALIBRATE_DELAY
332	def_bool y
333
334config ARCH_HAS_CPU_RELAX
335	def_bool y
336
337config ARCH_HAS_FILTER_PGPROT
338	def_bool y
339
340config ARCH_HIBERNATION_POSSIBLE
341	def_bool y
342
343config ARCH_NR_GPIO
344	int
345	default 1024 if X86_64
346	default 512
347
348config ARCH_SUSPEND_POSSIBLE
349	def_bool y
350
351config ARCH_WANT_GENERAL_HUGETLB
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	default y
466	help
467	  Compile kernel with the retpoline compiler options to guard against
468	  kernel-to-user data leaks by avoiding speculative indirect
469	  branches. Requires a compiler with -mindirect-branch=thunk-extern
470	  support for full protection. The kernel may run slower.
471
472config CC_HAS_SLS
473	def_bool $(cc-option,-mharden-sls=all)
474
475config SLS
476	bool "Mitigate Straight-Line-Speculation"
477	depends on CC_HAS_SLS && X86_64
478	default n
479	help
480	  Compile the kernel with straight-line-speculation options to guard
481	  against straight line speculation. The kernel image might be slightly
482	  larger.
483
484config X86_CPU_RESCTRL
485	bool "x86 CPU resource control support"
486	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
487	select KERNFS
488	select PROC_CPU_RESCTRL		if PROC_FS
489	help
490	  Enable x86 CPU resource control support.
491
492	  Provide support for the allocation and monitoring of system resources
493	  usage by the CPU.
494
495	  Intel calls this Intel Resource Director Technology
496	  (Intel(R) RDT). More information about RDT can be found in the
497	  Intel x86 Architecture Software Developer Manual.
498
499	  AMD calls this AMD Platform Quality of Service (AMD QoS).
500	  More information about AMD QoS can be found in the AMD64 Technology
501	  Platform Quality of Service Extensions manual.
502
503	  Say N if unsure.
504
505if X86_32
506config X86_BIGSMP
507	bool "Support for big SMP systems with more than 8 CPUs"
508	depends on SMP
509	help
510	  This option is needed for the systems that have more than 8 CPUs.
511
512config X86_EXTENDED_PLATFORM
513	bool "Support for extended (non-PC) x86 platforms"
514	default y
515	help
516	  If you disable this option then the kernel will only support
517	  standard PC platforms. (which covers the vast majority of
518	  systems out there.)
519
520	  If you enable this option then you'll be able to select support
521	  for the following (non-PC) 32 bit x86 platforms:
522		Goldfish (Android emulator)
523		AMD Elan
524		RDC R-321x SoC
525		SGI 320/540 (Visual Workstation)
526		STA2X11-based (e.g. Northville)
527		Moorestown MID devices
528
529	  If you have one of these systems, or if you want to build a
530	  generic distribution kernel, say Y here - otherwise say N.
531endif
532
533if X86_64
534config X86_EXTENDED_PLATFORM
535	bool "Support for extended (non-PC) x86 platforms"
536	default y
537	help
538	  If you disable this option then the kernel will only support
539	  standard PC platforms. (which covers the vast majority of
540	  systems out there.)
541
542	  If you enable this option then you'll be able to select support
543	  for the following (non-PC) 64 bit x86 platforms:
544		Numascale NumaChip
545		ScaleMP vSMP
546		SGI Ultraviolet
547
548	  If you have one of these systems, or if you want to build a
549	  generic distribution kernel, say Y here - otherwise say N.
550endif
551# This is an alphabetically sorted list of 64 bit extended platforms
552# Please maintain the alphabetic order if and when there are additions
553config X86_NUMACHIP
554	bool "Numascale NumaChip"
555	depends on X86_64
556	depends on X86_EXTENDED_PLATFORM
557	depends on NUMA
558	depends on SMP
559	depends on X86_X2APIC
560	depends on PCI_MMCONFIG
561	help
562	  Adds support for Numascale NumaChip large-SMP systems. Needed to
563	  enable more than ~168 cores.
564	  If you don't have one of these, you should say N here.
565
566config X86_VSMP
567	bool "ScaleMP vSMP"
568	select HYPERVISOR_GUEST
569	select PARAVIRT
570	depends on X86_64 && PCI
571	depends on X86_EXTENDED_PLATFORM
572	depends on SMP
573	help
574	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
575	  supposed to run on these EM64T-based machines.  Only choose this option
576	  if you have one of these machines.
577
578config X86_UV
579	bool "SGI Ultraviolet"
580	depends on X86_64
581	depends on X86_EXTENDED_PLATFORM
582	depends on NUMA
583	depends on EFI
584	depends on KEXEC_CORE
585	depends on X86_X2APIC
586	depends on PCI
587	help
588	  This option is needed in order to support SGI Ultraviolet systems.
589	  If you don't have one of these, you should say N here.
590
591# Following is an alphabetically sorted list of 32 bit extended platforms
592# Please maintain the alphabetic order if and when there are additions
593
594config X86_GOLDFISH
595	bool "Goldfish (Virtual Platform)"
596	depends on X86_EXTENDED_PLATFORM
597	help
598	 Enable support for the Goldfish virtual platform used primarily
599	 for Android development. Unless you are building for the Android
600	 Goldfish emulator say N here.
601
602config X86_INTEL_CE
603	bool "CE4100 TV platform"
604	depends on PCI
605	depends on PCI_GODIRECT
606	depends on X86_IO_APIC
607	depends on X86_32
608	depends on X86_EXTENDED_PLATFORM
609	select X86_REBOOTFIXUPS
610	select OF
611	select OF_EARLY_FLATTREE
612	help
613	  Select for the Intel CE media processor (CE4100) SOC.
614	  This option compiles in support for the CE4100 SOC for settop
615	  boxes and media devices.
616
617config X86_INTEL_MID
618	bool "Intel MID platform support"
619	depends on X86_EXTENDED_PLATFORM
620	depends on X86_PLATFORM_DEVICES
621	depends on PCI
622	depends on X86_64 || (PCI_GOANY && X86_32)
623	depends on X86_IO_APIC
624	select I2C
625	select DW_APB_TIMER
626	select INTEL_SCU_PCI
627	help
628	  Select to build a kernel capable of supporting Intel MID (Mobile
629	  Internet Device) platform systems which do not have the PCI legacy
630	  interfaces. If you are building for a PC class system say N here.
631
632	  Intel MID platforms are based on an Intel processor and chipset which
633	  consume less power than most of the x86 derivatives.
634
635config X86_INTEL_QUARK
636	bool "Intel Quark platform support"
637	depends on X86_32
638	depends on X86_EXTENDED_PLATFORM
639	depends on X86_PLATFORM_DEVICES
640	depends on X86_TSC
641	depends on PCI
642	depends on PCI_GOANY
643	depends on X86_IO_APIC
644	select IOSF_MBI
645	select INTEL_IMR
646	select COMMON_CLK
647	help
648	  Select to include support for Quark X1000 SoC.
649	  Say Y here if you have a Quark based system such as the Arduino
650	  compatible Intel Galileo.
651
652config X86_INTEL_LPSS
653	bool "Intel Low Power Subsystem Support"
654	depends on X86 && ACPI && PCI
655	select COMMON_CLK
656	select PINCTRL
657	select IOSF_MBI
658	help
659	  Select to build support for Intel Low Power Subsystem such as
660	  found on Intel Lynxpoint PCH. Selecting this option enables
661	  things like clock tree (common clock framework) and pincontrol
662	  which are needed by the LPSS peripheral drivers.
663
664config X86_AMD_PLATFORM_DEVICE
665	bool "AMD ACPI2Platform devices support"
666	depends on ACPI
667	select COMMON_CLK
668	select PINCTRL
669	help
670	  Select to interpret AMD specific ACPI device to platform device
671	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
672	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
673	  implemented under PINCTRL subsystem.
674
675config IOSF_MBI
676	tristate "Intel SoC IOSF Sideband support for SoC platforms"
677	depends on PCI
678	help
679	  This option enables sideband register access support for Intel SoC
680	  platforms. On these platforms the IOSF sideband is used in lieu of
681	  MSR's for some register accesses, mostly but not limited to thermal
682	  and power. Drivers may query the availability of this device to
683	  determine if they need the sideband in order to work on these
684	  platforms. The sideband is available on the following SoC products.
685	  This list is not meant to be exclusive.
686	   - BayTrail
687	   - Braswell
688	   - Quark
689
690	  You should say Y if you are running a kernel on one of these SoC's.
691
692config IOSF_MBI_DEBUG
693	bool "Enable IOSF sideband access through debugfs"
694	depends on IOSF_MBI && DEBUG_FS
695	help
696	  Select this option to expose the IOSF sideband access registers (MCR,
697	  MDR, MCRX) through debugfs to write and read register information from
698	  different units on the SoC. This is most useful for obtaining device
699	  state information for debug and analysis. As this is a general access
700	  mechanism, users of this option would have specific knowledge of the
701	  device they want to access.
702
703	  If you don't require the option or are in doubt, say N.
704
705config X86_RDC321X
706	bool "RDC R-321x SoC"
707	depends on X86_32
708	depends on X86_EXTENDED_PLATFORM
709	select M486
710	select X86_REBOOTFIXUPS
711	help
712	  This option is needed for RDC R-321x system-on-chip, also known
713	  as R-8610-(G).
714	  If you don't have one of these chips, you should say N here.
715
716config X86_32_NON_STANDARD
717	bool "Support non-standard 32-bit SMP architectures"
718	depends on X86_32 && SMP
719	depends on X86_EXTENDED_PLATFORM
720	help
721	  This option compiles in the bigsmp and STA2X11 default
722	  subarchitectures.  It is intended for a generic binary
723	  kernel. If you select them all, kernel will probe it one by
724	  one and will fallback to default.
725
726# Alphabetically sorted list of Non standard 32 bit platforms
727
728config X86_SUPPORTS_MEMORY_FAILURE
729	def_bool y
730	# MCE code calls memory_failure():
731	depends on X86_MCE
732	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
733	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
734	depends on X86_64 || !SPARSEMEM
735	select ARCH_SUPPORTS_MEMORY_FAILURE
736
737config STA2X11
738	bool "STA2X11 Companion Chip Support"
739	depends on X86_32_NON_STANDARD && PCI
740	select SWIOTLB
741	select MFD_STA2X11
742	select GPIOLIB
743	help
744	  This adds support for boards based on the STA2X11 IO-Hub,
745	  a.k.a. "ConneXt". The chip is used in place of the standard
746	  PC chipset, so all "standard" peripherals are missing. If this
747	  option is selected the kernel will still be able to boot on
748	  standard PC machines.
749
750config X86_32_IRIS
751	tristate "Eurobraille/Iris poweroff module"
752	depends on X86_32
753	help
754	  The Iris machines from EuroBraille do not have APM or ACPI support
755	  to shut themselves down properly.  A special I/O sequence is
756	  needed to do so, which is what this module does at
757	  kernel shutdown.
758
759	  This is only for Iris machines from EuroBraille.
760
761	  If unused, say N.
762
763config SCHED_OMIT_FRAME_POINTER
764	def_bool y
765	prompt "Single-depth WCHAN output"
766	depends on X86
767	help
768	  Calculate simpler /proc/<PID>/wchan values. If this option
769	  is disabled then wchan values will recurse back to the
770	  caller function. This provides more accurate wchan values,
771	  at the expense of slightly more scheduling overhead.
772
773	  If in doubt, say "Y".
774
775menuconfig HYPERVISOR_GUEST
776	bool "Linux guest support"
777	help
778	  Say Y here to enable options for running Linux under various hyper-
779	  visors. This option enables basic hypervisor detection and platform
780	  setup.
781
782	  If you say N, all options in this submenu will be skipped and
783	  disabled, and Linux guest support won't be built in.
784
785if HYPERVISOR_GUEST
786
787config PARAVIRT
788	bool "Enable paravirtualization code"
789	depends on HAVE_STATIC_CALL
790	help
791	  This changes the kernel so it can modify itself when it is run
792	  under a hypervisor, potentially improving performance significantly
793	  over full virtualization.  However, when run without a hypervisor
794	  the kernel is theoretically slower and slightly larger.
795
796config PARAVIRT_XXL
797	bool
798
799config PARAVIRT_DEBUG
800	bool "paravirt-ops debugging"
801	depends on PARAVIRT && DEBUG_KERNEL
802	help
803	  Enable to debug paravirt_ops internals.  Specifically, BUG if
804	  a paravirt_op is missing when it is called.
805
806config PARAVIRT_SPINLOCKS
807	bool "Paravirtualization layer for spinlocks"
808	depends on PARAVIRT && SMP
809	help
810	  Paravirtualized spinlocks allow a pvops backend to replace the
811	  spinlock implementation with something virtualization-friendly
812	  (for example, block the virtual CPU rather than spinning).
813
814	  It has a minimal impact on native kernels and gives a nice performance
815	  benefit on paravirtualized KVM / Xen kernels.
816
817	  If you are unsure how to answer this question, answer Y.
818
819config X86_HV_CALLBACK_VECTOR
820	def_bool n
821
822source "arch/x86/xen/Kconfig"
823
824config KVM_GUEST
825	bool "KVM Guest support (including kvmclock)"
826	depends on PARAVIRT
827	select PARAVIRT_CLOCK
828	select ARCH_CPUIDLE_HALTPOLL
829	select X86_HV_CALLBACK_VECTOR
830	default y
831	help
832	  This option enables various optimizations for running under the KVM
833	  hypervisor. It includes a paravirtualized clock, so that instead
834	  of relying on a PIT (or probably other) emulation by the
835	  underlying device model, the host provides the guest with
836	  timing infrastructure such as time of day, and system time
837
838config ARCH_CPUIDLE_HALTPOLL
839	def_bool n
840	prompt "Disable host haltpoll when loading haltpoll driver"
841	help
842	  If virtualized under KVM, disable host haltpoll.
843
844config PVH
845	bool "Support for running PVH guests"
846	help
847	  This option enables the PVH entry point for guest virtual machines
848	  as specified in the x86/HVM direct boot ABI.
849
850config PARAVIRT_TIME_ACCOUNTING
851	bool "Paravirtual steal time accounting"
852	depends on PARAVIRT
853	help
854	  Select this option to enable fine granularity task steal time
855	  accounting. Time spent executing other tasks in parallel with
856	  the current vCPU is discounted from the vCPU power. To account for
857	  that, there can be a small performance impact.
858
859	  If in doubt, say N here.
860
861config PARAVIRT_CLOCK
862	bool
863
864config JAILHOUSE_GUEST
865	bool "Jailhouse non-root cell support"
866	depends on X86_64 && PCI
867	select X86_PM_TIMER
868	help
869	  This option allows to run Linux as guest in a Jailhouse non-root
870	  cell. You can leave this option disabled if you only want to start
871	  Jailhouse and run Linux afterwards in the root cell.
872
873config ACRN_GUEST
874	bool "ACRN Guest support"
875	depends on X86_64
876	select X86_HV_CALLBACK_VECTOR
877	help
878	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
879	  a flexible, lightweight reference open-source hypervisor, built with
880	  real-time and safety-criticality in mind. It is built for embedded
881	  IOT with small footprint and real-time features. More details can be
882	  found in https://projectacrn.org/.
883
884endif #HYPERVISOR_GUEST
885
886source "arch/x86/Kconfig.cpu"
887
888config HPET_TIMER
889	def_bool X86_64
890	prompt "HPET Timer Support" if X86_32
891	help
892	  Use the IA-PC HPET (High Precision Event Timer) to manage
893	  time in preference to the PIT and RTC, if a HPET is
894	  present.
895	  HPET is the next generation timer replacing legacy 8254s.
896	  The HPET provides a stable time base on SMP
897	  systems, unlike the TSC, but it is more expensive to access,
898	  as it is off-chip.  The interface used is documented
899	  in the HPET spec, revision 1.
900
901	  You can safely choose Y here.  However, HPET will only be
902	  activated if the platform and the BIOS support this feature.
903	  Otherwise the 8254 will be used for timing services.
904
905	  Choose N to continue using the legacy 8254 timer.
906
907config HPET_EMULATE_RTC
908	def_bool y
909	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
910
911# Mark as expert because too many people got it wrong.
912# The code disables itself when not needed.
913config DMI
914	default y
915	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
916	bool "Enable DMI scanning" if EXPERT
917	help
918	  Enabled scanning of DMI to identify machine quirks. Say Y
919	  here unless you have verified that your setup is not
920	  affected by entries in the DMI blacklist. Required by PNP
921	  BIOS code.
922
923config GART_IOMMU
924	bool "Old AMD GART IOMMU support"
925	select DMA_OPS
926	select IOMMU_HELPER
927	select SWIOTLB
928	depends on X86_64 && PCI && AMD_NB
929	help
930	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
931	  GART based hardware IOMMUs.
932
933	  The GART supports full DMA access for devices with 32-bit access
934	  limitations, on systems with more than 3 GB. This is usually needed
935	  for USB, sound, many IDE/SATA chipsets and some other devices.
936
937	  Newer systems typically have a modern AMD IOMMU, supported via
938	  the CONFIG_AMD_IOMMU=y config option.
939
940	  In normal configurations this driver is only active when needed:
941	  there's more than 3 GB of memory and the system contains a
942	  32-bit limited device.
943
944	  If unsure, say Y.
945
946config MAXSMP
947	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
948	depends on X86_64 && SMP && DEBUG_KERNEL
949	select CPUMASK_OFFSTACK
950	help
951	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
952	  If unsure, say N.
953
954#
955# The maximum number of CPUs supported:
956#
957# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
958# and which can be configured interactively in the
959# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
960#
961# The ranges are different on 32-bit and 64-bit kernels, depending on
962# hardware capabilities and scalability features of the kernel.
963#
964# ( If MAXSMP is enabled we just use the highest possible value and disable
965#   interactive configuration. )
966#
967
968config NR_CPUS_RANGE_BEGIN
969	int
970	default NR_CPUS_RANGE_END if MAXSMP
971	default    1 if !SMP
972	default    2
973
974config NR_CPUS_RANGE_END
975	int
976	depends on X86_32
977	default   64 if  SMP &&  X86_BIGSMP
978	default    8 if  SMP && !X86_BIGSMP
979	default    1 if !SMP
980
981config NR_CPUS_RANGE_END
982	int
983	depends on X86_64
984	default 8192 if  SMP && CPUMASK_OFFSTACK
985	default  512 if  SMP && !CPUMASK_OFFSTACK
986	default    1 if !SMP
987
988config NR_CPUS_DEFAULT
989	int
990	depends on X86_32
991	default   32 if  X86_BIGSMP
992	default    8 if  SMP
993	default    1 if !SMP
994
995config NR_CPUS_DEFAULT
996	int
997	depends on X86_64
998	default 8192 if  MAXSMP
999	default   64 if  SMP
1000	default    1 if !SMP
1001
1002config NR_CPUS
1003	int "Maximum number of CPUs" if SMP && !MAXSMP
1004	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1005	default NR_CPUS_DEFAULT
1006	help
1007	  This allows you to specify the maximum number of CPUs which this
1008	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1009	  supported value is 8192, otherwise the maximum value is 512.  The
1010	  minimum value which makes sense is 2.
1011
1012	  This is purely to save memory: each supported CPU adds about 8KB
1013	  to the kernel image.
1014
1015config SCHED_CLUSTER
1016	bool "Cluster scheduler support"
1017	depends on SMP
1018	default y
1019	help
1020	  Cluster scheduler support improves the CPU scheduler's decision
1021	  making when dealing with machines that have clusters of CPUs.
1022	  Cluster usually means a couple of CPUs which are placed closely
1023	  by sharing mid-level caches, last-level cache tags or internal
1024	  busses.
1025
1026config SCHED_SMT
1027	def_bool y if SMP
1028
1029config SCHED_MC
1030	def_bool y
1031	prompt "Multi-core scheduler support"
1032	depends on SMP
1033	help
1034	  Multi-core scheduler support improves the CPU scheduler's decision
1035	  making when dealing with multi-core CPU chips at a cost of slightly
1036	  increased overhead in some places. If unsure say N here.
1037
1038config SCHED_MC_PRIO
1039	bool "CPU core priorities scheduler support"
1040	depends on SCHED_MC && CPU_SUP_INTEL
1041	select X86_INTEL_PSTATE
1042	select CPU_FREQ
1043	default y
1044	help
1045	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1046	  core ordering determined at manufacturing time, which allows
1047	  certain cores to reach higher turbo frequencies (when running
1048	  single threaded workloads) than others.
1049
1050	  Enabling this kernel feature teaches the scheduler about
1051	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1052	  scheduler's CPU selection logic accordingly, so that higher
1053	  overall system performance can be achieved.
1054
1055	  This feature will have no effect on CPUs without this feature.
1056
1057	  If unsure say Y here.
1058
1059config UP_LATE_INIT
1060	def_bool y
1061	depends on !SMP && X86_LOCAL_APIC
1062
1063config X86_UP_APIC
1064	bool "Local APIC support on uniprocessors" if !PCI_MSI
1065	default PCI_MSI
1066	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1067	help
1068	  A local APIC (Advanced Programmable Interrupt Controller) is an
1069	  integrated interrupt controller in the CPU. If you have a single-CPU
1070	  system which has a processor with a local APIC, you can say Y here to
1071	  enable and use it. If you say Y here even though your machine doesn't
1072	  have a local APIC, then the kernel will still run with no slowdown at
1073	  all. The local APIC supports CPU-generated self-interrupts (timer,
1074	  performance counters), and the NMI watchdog which detects hard
1075	  lockups.
1076
1077config X86_UP_IOAPIC
1078	bool "IO-APIC support on uniprocessors"
1079	depends on X86_UP_APIC
1080	help
1081	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1082	  SMP-capable replacement for PC-style interrupt controllers. Most
1083	  SMP systems and many recent uniprocessor systems have one.
1084
1085	  If you have a single-CPU system with an IO-APIC, you can say Y here
1086	  to use it. If you say Y here even though your machine doesn't have
1087	  an IO-APIC, then the kernel will still run with no slowdown at all.
1088
1089config X86_LOCAL_APIC
1090	def_bool y
1091	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1092	select IRQ_DOMAIN_HIERARCHY
1093	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1094
1095config X86_IO_APIC
1096	def_bool y
1097	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1098
1099config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1100	bool "Reroute for broken boot IRQs"
1101	depends on X86_IO_APIC
1102	help
1103	  This option enables a workaround that fixes a source of
1104	  spurious interrupts. This is recommended when threaded
1105	  interrupt handling is used on systems where the generation of
1106	  superfluous "boot interrupts" cannot be disabled.
1107
1108	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1109	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1110	  kernel does during interrupt handling). On chipsets where this
1111	  boot IRQ generation cannot be disabled, this workaround keeps
1112	  the original IRQ line masked so that only the equivalent "boot
1113	  IRQ" is delivered to the CPUs. The workaround also tells the
1114	  kernel to set up the IRQ handler on the boot IRQ line. In this
1115	  way only one interrupt is delivered to the kernel. Otherwise
1116	  the spurious second interrupt may cause the kernel to bring
1117	  down (vital) interrupt lines.
1118
1119	  Only affects "broken" chipsets. Interrupt sharing may be
1120	  increased on these systems.
1121
1122config X86_MCE
1123	bool "Machine Check / overheating reporting"
1124	select GENERIC_ALLOCATOR
1125	default y
1126	help
1127	  Machine Check support allows the processor to notify the
1128	  kernel if it detects a problem (e.g. overheating, data corruption).
1129	  The action the kernel takes depends on the severity of the problem,
1130	  ranging from warning messages to halting the machine.
1131
1132config X86_MCELOG_LEGACY
1133	bool "Support for deprecated /dev/mcelog character device"
1134	depends on X86_MCE
1135	help
1136	  Enable support for /dev/mcelog which is needed by the old mcelog
1137	  userspace logging daemon. Consider switching to the new generation
1138	  rasdaemon solution.
1139
1140config X86_MCE_INTEL
1141	def_bool y
1142	prompt "Intel MCE features"
1143	depends on X86_MCE && X86_LOCAL_APIC
1144	help
1145	   Additional support for intel specific MCE features such as
1146	   the thermal monitor.
1147
1148config X86_MCE_AMD
1149	def_bool y
1150	prompt "AMD MCE features"
1151	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1152	help
1153	   Additional support for AMD specific MCE features such as
1154	   the DRAM Error Threshold.
1155
1156config X86_ANCIENT_MCE
1157	bool "Support for old Pentium 5 / WinChip machine checks"
1158	depends on X86_32 && X86_MCE
1159	help
1160	  Include support for machine check handling on old Pentium 5 or WinChip
1161	  systems. These typically need to be enabled explicitly on the command
1162	  line.
1163
1164config X86_MCE_THRESHOLD
1165	depends on X86_MCE_AMD || X86_MCE_INTEL
1166	def_bool y
1167
1168config X86_MCE_INJECT
1169	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1170	tristate "Machine check injector support"
1171	help
1172	  Provide support for injecting machine checks for testing purposes.
1173	  If you don't know what a machine check is and you don't do kernel
1174	  QA it is safe to say n.
1175
1176source "arch/x86/events/Kconfig"
1177
1178config X86_LEGACY_VM86
1179	bool "Legacy VM86 support"
1180	depends on X86_32
1181	help
1182	  This option allows user programs to put the CPU into V8086
1183	  mode, which is an 80286-era approximation of 16-bit real mode.
1184
1185	  Some very old versions of X and/or vbetool require this option
1186	  for user mode setting.  Similarly, DOSEMU will use it if
1187	  available to accelerate real mode DOS programs.  However, any
1188	  recent version of DOSEMU, X, or vbetool should be fully
1189	  functional even without kernel VM86 support, as they will all
1190	  fall back to software emulation. Nevertheless, if you are using
1191	  a 16-bit DOS program where 16-bit performance matters, vm86
1192	  mode might be faster than emulation and you might want to
1193	  enable this option.
1194
1195	  Note that any app that works on a 64-bit kernel is unlikely to
1196	  need this option, as 64-bit kernels don't, and can't, support
1197	  V8086 mode. This option is also unrelated to 16-bit protected
1198	  mode and is not needed to run most 16-bit programs under Wine.
1199
1200	  Enabling this option increases the complexity of the kernel
1201	  and slows down exception handling a tiny bit.
1202
1203	  If unsure, say N here.
1204
1205config VM86
1206	bool
1207	default X86_LEGACY_VM86
1208
1209config X86_16BIT
1210	bool "Enable support for 16-bit segments" if EXPERT
1211	default y
1212	depends on MODIFY_LDT_SYSCALL
1213	help
1214	  This option is required by programs like Wine to run 16-bit
1215	  protected mode legacy code on x86 processors.  Disabling
1216	  this option saves about 300 bytes on i386, or around 6K text
1217	  plus 16K runtime memory on x86-64,
1218
1219config X86_ESPFIX32
1220	def_bool y
1221	depends on X86_16BIT && X86_32
1222
1223config X86_ESPFIX64
1224	def_bool y
1225	depends on X86_16BIT && X86_64
1226
1227config X86_VSYSCALL_EMULATION
1228	bool "Enable vsyscall emulation" if EXPERT
1229	default y
1230	depends on X86_64
1231	help
1232	 This enables emulation of the legacy vsyscall page.  Disabling
1233	 it is roughly equivalent to booting with vsyscall=none, except
1234	 that it will also disable the helpful warning if a program
1235	 tries to use a vsyscall.  With this option set to N, offending
1236	 programs will just segfault, citing addresses of the form
1237	 0xffffffffff600?00.
1238
1239	 This option is required by many programs built before 2013, and
1240	 care should be used even with newer programs if set to N.
1241
1242	 Disabling this option saves about 7K of kernel size and
1243	 possibly 4K of additional runtime pagetable memory.
1244
1245config X86_IOPL_IOPERM
1246	bool "IOPERM and IOPL Emulation"
1247	default y
1248	help
1249	  This enables the ioperm() and iopl() syscalls which are necessary
1250	  for legacy applications.
1251
1252	  Legacy IOPL support is an overbroad mechanism which allows user
1253	  space aside of accessing all 65536 I/O ports also to disable
1254	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1255	  capabilities and permission from potentially active security
1256	  modules.
1257
1258	  The emulation restricts the functionality of the syscall to
1259	  only allowing the full range I/O port access, but prevents the
1260	  ability to disable interrupts from user space which would be
1261	  granted if the hardware IOPL mechanism would be used.
1262
1263config TOSHIBA
1264	tristate "Toshiba Laptop support"
1265	depends on X86_32
1266	help
1267	  This adds a driver to safely access the System Management Mode of
1268	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1269	  not work on models with a Phoenix BIOS. The System Management Mode
1270	  is used to set the BIOS and power saving options on Toshiba portables.
1271
1272	  For information on utilities to make use of this driver see the
1273	  Toshiba Linux utilities web site at:
1274	  <http://www.buzzard.org.uk/toshiba/>.
1275
1276	  Say Y if you intend to run this kernel on a Toshiba portable.
1277	  Say N otherwise.
1278
1279config I8K
1280	tristate "Dell i8k legacy laptop support"
1281	depends on HWMON
1282	depends on PROC_FS
1283	select SENSORS_DELL_SMM
1284	help
1285	  This option enables legacy /proc/i8k userspace interface in hwmon
1286	  dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1287	  temperature and allows controlling fan speeds of Dell laptops via
1288	  System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1289	  it reports also power and hotkey status. For fan speed control is
1290	  needed userspace package i8kutils.
1291
1292	  Say Y if you intend to run this kernel on old Dell laptops or want to
1293	  use userspace package i8kutils.
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 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 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
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_SMAP
1840	def_bool y
1841	prompt "Supervisor Mode Access Prevention" if EXPERT
1842	help
1843	  Supervisor Mode Access Prevention (SMAP) is a security
1844	  feature in newer Intel processors.  There is a small
1845	  performance cost if this enabled and turned on; there is
1846	  also a small increase in the kernel size if this is enabled.
1847
1848	  If unsure, say Y.
1849
1850config X86_UMIP
1851	def_bool y
1852	prompt "User Mode Instruction Prevention" if EXPERT
1853	help
1854	  User Mode Instruction Prevention (UMIP) is a security feature in
1855	  some x86 processors. If enabled, a general protection fault is
1856	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1857	  executed in user mode. These instructions unnecessarily expose
1858	  information about the hardware state.
1859
1860	  The vast majority of applications do not use these instructions.
1861	  For the very few that do, software emulation is provided in
1862	  specific cases in protected and virtual-8086 modes. Emulated
1863	  results are dummy.
1864
1865config X86_INTEL_MEMORY_PROTECTION_KEYS
1866	prompt "Memory Protection Keys"
1867	def_bool y
1868	# Note: only available in 64-bit mode
1869	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1870	select ARCH_USES_HIGH_VMA_FLAGS
1871	select ARCH_HAS_PKEYS
1872	help
1873	  Memory Protection Keys provides a mechanism for enforcing
1874	  page-based protections, but without requiring modification of the
1875	  page tables when an application changes protection domains.
1876
1877	  For details, see Documentation/core-api/protection-keys.rst
1878
1879	  If unsure, say y.
1880
1881choice
1882	prompt "TSX enable mode"
1883	depends on CPU_SUP_INTEL
1884	default X86_INTEL_TSX_MODE_OFF
1885	help
1886	  Intel's TSX (Transactional Synchronization Extensions) feature
1887	  allows to optimize locking protocols through lock elision which
1888	  can lead to a noticeable performance boost.
1889
1890	  On the other hand it has been shown that TSX can be exploited
1891	  to form side channel attacks (e.g. TAA) and chances are there
1892	  will be more of those attacks discovered in the future.
1893
1894	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1895	  might override this decision by tsx=on the command line parameter.
1896	  Even with TSX enabled, the kernel will attempt to enable the best
1897	  possible TAA mitigation setting depending on the microcode available
1898	  for the particular machine.
1899
1900	  This option allows to set the default tsx mode between tsx=on, =off
1901	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1902	  details.
1903
1904	  Say off if not sure, auto if TSX is in use but it should be used on safe
1905	  platforms or on if TSX is in use and the security aspect of tsx is not
1906	  relevant.
1907
1908config X86_INTEL_TSX_MODE_OFF
1909	bool "off"
1910	help
1911	  TSX is disabled if possible - equals to tsx=off command line parameter.
1912
1913config X86_INTEL_TSX_MODE_ON
1914	bool "on"
1915	help
1916	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1917	  line parameter.
1918
1919config X86_INTEL_TSX_MODE_AUTO
1920	bool "auto"
1921	help
1922	  TSX is enabled on TSX capable HW that is believed to be safe against
1923	  side channel attacks- equals the tsx=auto command line parameter.
1924endchoice
1925
1926config X86_SGX
1927	bool "Software Guard eXtensions (SGX)"
1928	depends on X86_64 && CPU_SUP_INTEL
1929	depends on CRYPTO=y
1930	depends on CRYPTO_SHA256=y
1931	select SRCU
1932	select MMU_NOTIFIER
1933	select NUMA_KEEP_MEMINFO if NUMA
1934	select XARRAY_MULTI
1935	help
1936	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1937	  that can be used by applications to set aside private regions of code
1938	  and data, referred to as enclaves. An enclave's private memory can
1939	  only be accessed by code running within the enclave. Accesses from
1940	  outside the enclave, including other enclaves, are disallowed by
1941	  hardware.
1942
1943	  If unsure, say N.
1944
1945config EFI
1946	bool "EFI runtime service support"
1947	depends on ACPI
1948	select UCS2_STRING
1949	select EFI_RUNTIME_WRAPPERS
1950	select ARCH_USE_MEMREMAP_PROT
1951	help
1952	  This enables the kernel to use EFI runtime services that are
1953	  available (such as the EFI variable services).
1954
1955	  This option is only useful on systems that have EFI firmware.
1956	  In addition, you should use the latest ELILO loader available
1957	  at <http://elilo.sourceforge.net> in order to take advantage
1958	  of EFI runtime services. However, even with this option, the
1959	  resultant kernel should continue to boot on existing non-EFI
1960	  platforms.
1961
1962config EFI_STUB
1963	bool "EFI stub support"
1964	depends on EFI
1965	depends on $(cc-option,-mabi=ms) || X86_32
1966	select RELOCATABLE
1967	help
1968	  This kernel feature allows a bzImage to be loaded directly
1969	  by EFI firmware without the use of a bootloader.
1970
1971	  See Documentation/admin-guide/efi-stub.rst for more information.
1972
1973config EFI_MIXED
1974	bool "EFI mixed-mode support"
1975	depends on EFI_STUB && X86_64
1976	help
1977	   Enabling this feature allows a 64-bit kernel to be booted
1978	   on a 32-bit firmware, provided that your CPU supports 64-bit
1979	   mode.
1980
1981	   Note that it is not possible to boot a mixed-mode enabled
1982	   kernel via the EFI boot stub - a bootloader that supports
1983	   the EFI handover protocol must be used.
1984
1985	   If unsure, say N.
1986
1987source "kernel/Kconfig.hz"
1988
1989config KEXEC
1990	bool "kexec system call"
1991	select KEXEC_CORE
1992	help
1993	  kexec is a system call that implements the ability to shutdown your
1994	  current kernel, and to start another kernel.  It is like a reboot
1995	  but it is independent of the system firmware.   And like a reboot
1996	  you can start any kernel with it, not just Linux.
1997
1998	  The name comes from the similarity to the exec system call.
1999
2000	  It is an ongoing process to be certain the hardware in a machine
2001	  is properly shutdown, so do not be surprised if this code does not
2002	  initially work for you.  As of this writing the exact hardware
2003	  interface is strongly in flux, so no good recommendation can be
2004	  made.
2005
2006config KEXEC_FILE
2007	bool "kexec file based system call"
2008	select KEXEC_CORE
2009	select BUILD_BIN2C
2010	depends on X86_64
2011	depends on CRYPTO=y
2012	depends on CRYPTO_SHA256=y
2013	help
2014	  This is new version of kexec system call. This system call is
2015	  file based and takes file descriptors as system call argument
2016	  for kernel and initramfs as opposed to list of segments as
2017	  accepted by previous system call.
2018
2019config ARCH_HAS_KEXEC_PURGATORY
2020	def_bool KEXEC_FILE
2021
2022config KEXEC_SIG
2023	bool "Verify kernel signature during kexec_file_load() syscall"
2024	depends on KEXEC_FILE
2025	help
2026
2027	  This option makes the kexec_file_load() syscall check for a valid
2028	  signature of the kernel image.  The image can still be loaded without
2029	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2030	  there's a signature that we can check, then it must be valid.
2031
2032	  In addition to this option, you need to enable signature
2033	  verification for the corresponding kernel image type being
2034	  loaded in order for this to work.
2035
2036config KEXEC_SIG_FORCE
2037	bool "Require a valid signature in kexec_file_load() syscall"
2038	depends on KEXEC_SIG
2039	help
2040	  This option makes kernel signature verification mandatory for
2041	  the kexec_file_load() syscall.
2042
2043config KEXEC_BZIMAGE_VERIFY_SIG
2044	bool "Enable bzImage signature verification support"
2045	depends on KEXEC_SIG
2046	depends on SIGNED_PE_FILE_VERIFICATION
2047	select SYSTEM_TRUSTED_KEYRING
2048	help
2049	  Enable bzImage signature verification support.
2050
2051config CRASH_DUMP
2052	bool "kernel crash dumps"
2053	depends on X86_64 || (X86_32 && HIGHMEM)
2054	help
2055	  Generate crash dump after being started by kexec.
2056	  This should be normally only set in special crash dump kernels
2057	  which are loaded in the main kernel with kexec-tools into
2058	  a specially reserved region and then later executed after
2059	  a crash by kdump/kexec. The crash dump kernel must be compiled
2060	  to a memory address not used by the main kernel or BIOS using
2061	  PHYSICAL_START, or it must be built as a relocatable image
2062	  (CONFIG_RELOCATABLE=y).
2063	  For more details see Documentation/admin-guide/kdump/kdump.rst
2064
2065config KEXEC_JUMP
2066	bool "kexec jump"
2067	depends on KEXEC && HIBERNATION
2068	help
2069	  Jump between original kernel and kexeced kernel and invoke
2070	  code in physical address mode via KEXEC
2071
2072config PHYSICAL_START
2073	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2074	default "0x1000000"
2075	help
2076	  This gives the physical address where the kernel is loaded.
2077
2078	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2079	  bzImage will decompress itself to above physical address and
2080	  run from there. Otherwise, bzImage will run from the address where
2081	  it has been loaded by the boot loader and will ignore above physical
2082	  address.
2083
2084	  In normal kdump cases one does not have to set/change this option
2085	  as now bzImage can be compiled as a completely relocatable image
2086	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2087	  address. This option is mainly useful for the folks who don't want
2088	  to use a bzImage for capturing the crash dump and want to use a
2089	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2090	  to be specifically compiled to run from a specific memory area
2091	  (normally a reserved region) and this option comes handy.
2092
2093	  So if you are using bzImage for capturing the crash dump,
2094	  leave the value here unchanged to 0x1000000 and set
2095	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2096	  for capturing the crash dump change this value to start of
2097	  the reserved region.  In other words, it can be set based on
2098	  the "X" value as specified in the "crashkernel=YM@XM"
2099	  command line boot parameter passed to the panic-ed
2100	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2101	  for more details about crash dumps.
2102
2103	  Usage of bzImage for capturing the crash dump is recommended as
2104	  one does not have to build two kernels. Same kernel can be used
2105	  as production kernel and capture kernel. Above option should have
2106	  gone away after relocatable bzImage support is introduced. But it
2107	  is present because there are users out there who continue to use
2108	  vmlinux for dump capture. This option should go away down the
2109	  line.
2110
2111	  Don't change this unless you know what you are doing.
2112
2113config RELOCATABLE
2114	bool "Build a relocatable kernel"
2115	default y
2116	help
2117	  This builds a kernel image that retains relocation information
2118	  so it can be loaded someplace besides the default 1MB.
2119	  The relocations tend to make the kernel binary about 10% larger,
2120	  but are discarded at runtime.
2121
2122	  One use is for the kexec on panic case where the recovery kernel
2123	  must live at a different physical address than the primary
2124	  kernel.
2125
2126	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2127	  it has been loaded at and the compile time physical address
2128	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2129
2130config RANDOMIZE_BASE
2131	bool "Randomize the address of the kernel image (KASLR)"
2132	depends on RELOCATABLE
2133	default y
2134	help
2135	  In support of Kernel Address Space Layout Randomization (KASLR),
2136	  this randomizes the physical address at which the kernel image
2137	  is decompressed and the virtual address where the kernel
2138	  image is mapped, as a security feature that deters exploit
2139	  attempts relying on knowledge of the location of kernel
2140	  code internals.
2141
2142	  On 64-bit, the kernel physical and virtual addresses are
2143	  randomized separately. The physical address will be anywhere
2144	  between 16MB and the top of physical memory (up to 64TB). The
2145	  virtual address will be randomized from 16MB up to 1GB (9 bits
2146	  of entropy). Note that this also reduces the memory space
2147	  available to kernel modules from 1.5GB to 1GB.
2148
2149	  On 32-bit, the kernel physical and virtual addresses are
2150	  randomized together. They will be randomized from 16MB up to
2151	  512MB (8 bits of entropy).
2152
2153	  Entropy is generated using the RDRAND instruction if it is
2154	  supported. If RDTSC is supported, its value is mixed into
2155	  the entropy pool as well. If neither RDRAND nor RDTSC are
2156	  supported, then entropy is read from the i8254 timer. The
2157	  usable entropy is limited by the kernel being built using
2158	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2159	  minimum of 2MB. As a result, only 10 bits of entropy are
2160	  theoretically possible, but the implementations are further
2161	  limited due to memory layouts.
2162
2163	  If unsure, say Y.
2164
2165# Relocation on x86 needs some additional build support
2166config X86_NEED_RELOCS
2167	def_bool y
2168	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2169
2170config PHYSICAL_ALIGN
2171	hex "Alignment value to which kernel should be aligned"
2172	default "0x200000"
2173	range 0x2000 0x1000000 if X86_32
2174	range 0x200000 0x1000000 if X86_64
2175	help
2176	  This value puts the alignment restrictions on physical address
2177	  where kernel is loaded and run from. Kernel is compiled for an
2178	  address which meets above alignment restriction.
2179
2180	  If bootloader loads the kernel at a non-aligned address and
2181	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2182	  address aligned to above value and run from there.
2183
2184	  If bootloader loads the kernel at a non-aligned address and
2185	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2186	  load address and decompress itself to the address it has been
2187	  compiled for and run from there. The address for which kernel is
2188	  compiled already meets above alignment restrictions. Hence the
2189	  end result is that kernel runs from a physical address meeting
2190	  above alignment restrictions.
2191
2192	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2193	  this value must be a multiple of 0x200000.
2194
2195	  Don't change this unless you know what you are doing.
2196
2197config DYNAMIC_MEMORY_LAYOUT
2198	bool
2199	help
2200	  This option makes base addresses of vmalloc and vmemmap as well as
2201	  __PAGE_OFFSET movable during boot.
2202
2203config RANDOMIZE_MEMORY
2204	bool "Randomize the kernel memory sections"
2205	depends on X86_64
2206	depends on RANDOMIZE_BASE
2207	select DYNAMIC_MEMORY_LAYOUT
2208	default RANDOMIZE_BASE
2209	help
2210	   Randomizes the base virtual address of kernel memory sections
2211	   (physical memory mapping, vmalloc & vmemmap). This security feature
2212	   makes exploits relying on predictable memory locations less reliable.
2213
2214	   The order of allocations remains unchanged. Entropy is generated in
2215	   the same way as RANDOMIZE_BASE. Current implementation in the optimal
2216	   configuration have in average 30,000 different possible virtual
2217	   addresses for each memory section.
2218
2219	   If unsure, say Y.
2220
2221config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2222	hex "Physical memory mapping padding" if EXPERT
2223	depends on RANDOMIZE_MEMORY
2224	default "0xa" if MEMORY_HOTPLUG
2225	default "0x0"
2226	range 0x1 0x40 if MEMORY_HOTPLUG
2227	range 0x0 0x40
2228	help
2229	   Define the padding in terabytes added to the existing physical
2230	   memory size during kernel memory randomization. It is useful
2231	   for memory hotplug support but reduces the entropy available for
2232	   address randomization.
2233
2234	   If unsure, leave at the default value.
2235
2236config HOTPLUG_CPU
2237	def_bool y
2238	depends on SMP
2239
2240config BOOTPARAM_HOTPLUG_CPU0
2241	bool "Set default setting of cpu0_hotpluggable"
2242	depends on HOTPLUG_CPU
2243	help
2244	  Set whether default state of cpu0_hotpluggable is on or off.
2245
2246	  Say Y here to enable CPU0 hotplug by default. If this switch
2247	  is turned on, there is no need to give cpu0_hotplug kernel
2248	  parameter and the CPU0 hotplug feature is enabled by default.
2249
2250	  Please note: there are two known CPU0 dependencies if you want
2251	  to enable the CPU0 hotplug feature either by this switch or by
2252	  cpu0_hotplug kernel parameter.
2253
2254	  First, resume from hibernate or suspend always starts from CPU0.
2255	  So hibernate and suspend are prevented if CPU0 is offline.
2256
2257	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2258	  offline if any interrupt can not migrate out of CPU0. There may
2259	  be other CPU0 dependencies.
2260
2261	  Please make sure the dependencies are under your control before
2262	  you enable this feature.
2263
2264	  Say N if you don't want to enable CPU0 hotplug feature by default.
2265	  You still can enable the CPU0 hotplug feature at boot by kernel
2266	  parameter cpu0_hotplug.
2267
2268config DEBUG_HOTPLUG_CPU0
2269	def_bool n
2270	prompt "Debug CPU0 hotplug"
2271	depends on HOTPLUG_CPU
2272	help
2273	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2274	  soon as possible and boots up userspace with CPU0 offlined. User
2275	  can online CPU0 back after boot time.
2276
2277	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2278	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2279	  compilation or giving cpu0_hotplug kernel parameter at boot.
2280
2281	  If unsure, say N.
2282
2283config COMPAT_VDSO
2284	def_bool n
2285	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2286	depends on COMPAT_32
2287	help
2288	  Certain buggy versions of glibc will crash if they are
2289	  presented with a 32-bit vDSO that is not mapped at the address
2290	  indicated in its segment table.
2291
2292	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2293	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2294	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2295	  the only released version with the bug, but OpenSUSE 9
2296	  contains a buggy "glibc 2.3.2".
2297
2298	  The symptom of the bug is that everything crashes on startup, saying:
2299	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2300
2301	  Saying Y here changes the default value of the vdso32 boot
2302	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2303	  This works around the glibc bug but hurts performance.
2304
2305	  If unsure, say N: if you are compiling your own kernel, you
2306	  are unlikely to be using a buggy version of glibc.
2307
2308choice
2309	prompt "vsyscall table for legacy applications"
2310	depends on X86_64
2311	default LEGACY_VSYSCALL_XONLY
2312	help
2313	  Legacy user code that does not know how to find the vDSO expects
2314	  to be able to issue three syscalls by calling fixed addresses in
2315	  kernel space. Since this location is not randomized with ASLR,
2316	  it can be used to assist security vulnerability exploitation.
2317
2318	  This setting can be changed at boot time via the kernel command
2319	  line parameter vsyscall=[emulate|xonly|none].
2320
2321	  On a system with recent enough glibc (2.14 or newer) and no
2322	  static binaries, you can say None without a performance penalty
2323	  to improve security.
2324
2325	  If unsure, select "Emulate execution only".
2326
2327	config LEGACY_VSYSCALL_EMULATE
2328		bool "Full emulation"
2329		help
2330		  The kernel traps and emulates calls into the fixed vsyscall
2331		  address mapping. This makes the mapping non-executable, but
2332		  it still contains readable known contents, which could be
2333		  used in certain rare security vulnerability exploits. This
2334		  configuration is recommended when using legacy userspace
2335		  that still uses vsyscalls along with legacy binary
2336		  instrumentation tools that require code to be readable.
2337
2338		  An example of this type of legacy userspace is running
2339		  Pin on an old binary that still uses vsyscalls.
2340
2341	config LEGACY_VSYSCALL_XONLY
2342		bool "Emulate execution only"
2343		help
2344		  The kernel traps and emulates calls into the fixed vsyscall
2345		  address mapping and does not allow reads.  This
2346		  configuration is recommended when userspace might use the
2347		  legacy vsyscall area but support for legacy binary
2348		  instrumentation of legacy code is not needed.  It mitigates
2349		  certain uses of the vsyscall area as an ASLR-bypassing
2350		  buffer.
2351
2352	config LEGACY_VSYSCALL_NONE
2353		bool "None"
2354		help
2355		  There will be no vsyscall mapping at all. This will
2356		  eliminate any risk of ASLR bypass due to the vsyscall
2357		  fixed address mapping. Attempts to use the vsyscalls
2358		  will be reported to dmesg, so that either old or
2359		  malicious userspace programs can be identified.
2360
2361endchoice
2362
2363config CMDLINE_BOOL
2364	bool "Built-in kernel command line"
2365	help
2366	  Allow for specifying boot arguments to the kernel at
2367	  build time.  On some systems (e.g. embedded ones), it is
2368	  necessary or convenient to provide some or all of the
2369	  kernel boot arguments with the kernel itself (that is,
2370	  to not rely on the boot loader to provide them.)
2371
2372	  To compile command line arguments into the kernel,
2373	  set this option to 'Y', then fill in the
2374	  boot arguments in CONFIG_CMDLINE.
2375
2376	  Systems with fully functional boot loaders (i.e. non-embedded)
2377	  should leave this option set to 'N'.
2378
2379config CMDLINE
2380	string "Built-in kernel command string"
2381	depends on CMDLINE_BOOL
2382	default ""
2383	help
2384	  Enter arguments here that should be compiled into the kernel
2385	  image and used at boot time.  If the boot loader provides a
2386	  command line at boot time, it is appended to this string to
2387	  form the full kernel command line, when the system boots.
2388
2389	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2390	  change this behavior.
2391
2392	  In most cases, the command line (whether built-in or provided
2393	  by the boot loader) should specify the device for the root
2394	  file system.
2395
2396config CMDLINE_OVERRIDE
2397	bool "Built-in command line overrides boot loader arguments"
2398	depends on CMDLINE_BOOL && CMDLINE != ""
2399	help
2400	  Set this option to 'Y' to have the kernel ignore the boot loader
2401	  command line, and use ONLY the built-in command line.
2402
2403	  This is used to work around broken boot loaders.  This should
2404	  be set to 'N' under normal conditions.
2405
2406config MODIFY_LDT_SYSCALL
2407	bool "Enable the LDT (local descriptor table)" if EXPERT
2408	default y
2409	help
2410	  Linux can allow user programs to install a per-process x86
2411	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2412	  call.  This is required to run 16-bit or segmented code such as
2413	  DOSEMU or some Wine programs.  It is also used by some very old
2414	  threading libraries.
2415
2416	  Enabling this feature adds a small amount of overhead to
2417	  context switches and increases the low-level kernel attack
2418	  surface.  Disabling it removes the modify_ldt(2) system call.
2419
2420	  Saying 'N' here may make sense for embedded or server kernels.
2421
2422config STRICT_SIGALTSTACK_SIZE
2423	bool "Enforce strict size checking for sigaltstack"
2424	depends on DYNAMIC_SIGFRAME
2425	help
2426	  For historical reasons MINSIGSTKSZ is a constant which became
2427	  already too small with AVX512 support. Add a mechanism to
2428	  enforce strict checking of the sigaltstack size against the
2429	  real size of the FPU frame. This option enables the check
2430	  by default. It can also be controlled via the kernel command
2431	  line option 'strict_sas_size' independent of this config
2432	  switch. Enabling it might break existing applications which
2433	  allocate a too small sigaltstack but 'work' because they
2434	  never get a signal delivered.
2435
2436	  Say 'N' unless you want to really enforce this check.
2437
2438source "kernel/livepatch/Kconfig"
2439
2440endmenu
2441
2442config ARCH_HAS_ADD_PAGES
2443	def_bool y
2444	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2445
2446config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2447	def_bool y
2448
2449menu "Power management and ACPI options"
2450
2451config ARCH_HIBERNATION_HEADER
2452	def_bool y
2453	depends on HIBERNATION
2454
2455source "kernel/power/Kconfig"
2456
2457source "drivers/acpi/Kconfig"
2458
2459config X86_APM_BOOT
2460	def_bool y
2461	depends on APM
2462
2463menuconfig APM
2464	tristate "APM (Advanced Power Management) BIOS support"
2465	depends on X86_32 && PM_SLEEP
2466	help
2467	  APM is a BIOS specification for saving power using several different
2468	  techniques. This is mostly useful for battery powered laptops with
2469	  APM compliant BIOSes. If you say Y here, the system time will be
2470	  reset after a RESUME operation, the /proc/apm device will provide
2471	  battery status information, and user-space programs will receive
2472	  notification of APM "events" (e.g. battery status change).
2473
2474	  If you select "Y" here, you can disable actual use of the APM
2475	  BIOS by passing the "apm=off" option to the kernel at boot time.
2476
2477	  Note that the APM support is almost completely disabled for
2478	  machines with more than one CPU.
2479
2480	  In order to use APM, you will need supporting software. For location
2481	  and more information, read <file:Documentation/power/apm-acpi.rst>
2482	  and the Battery Powered Linux mini-HOWTO, available from
2483	  <http://www.tldp.org/docs.html#howto>.
2484
2485	  This driver does not spin down disk drives (see the hdparm(8)
2486	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2487	  VESA-compliant "green" monitors.
2488
2489	  This driver does not support the TI 4000M TravelMate and the ACER
2490	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2491	  desktop machines also don't have compliant BIOSes, and this driver
2492	  may cause those machines to panic during the boot phase.
2493
2494	  Generally, if you don't have a battery in your machine, there isn't
2495	  much point in using this driver and you should say N. If you get
2496	  random kernel OOPSes or reboots that don't seem to be related to
2497	  anything, try disabling/enabling this option (or disabling/enabling
2498	  APM in your BIOS).
2499
2500	  Some other things you should try when experiencing seemingly random,
2501	  "weird" problems:
2502
2503	  1) make sure that you have enough swap space and that it is
2504	  enabled.
2505	  2) pass the "no-hlt" option to the kernel
2506	  3) switch on floating point emulation in the kernel and pass
2507	  the "no387" option to the kernel
2508	  4) pass the "floppy=nodma" option to the kernel
2509	  5) pass the "mem=4M" option to the kernel (thereby disabling
2510	  all but the first 4 MB of RAM)
2511	  6) make sure that the CPU is not over clocked.
2512	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2513	  8) disable the cache from your BIOS settings
2514	  9) install a fan for the video card or exchange video RAM
2515	  10) install a better fan for the CPU
2516	  11) exchange RAM chips
2517	  12) exchange the motherboard.
2518
2519	  To compile this driver as a module, choose M here: the
2520	  module will be called apm.
2521
2522if APM
2523
2524config APM_IGNORE_USER_SUSPEND
2525	bool "Ignore USER SUSPEND"
2526	help
2527	  This option will ignore USER SUSPEND requests. On machines with a
2528	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2529	  series notebooks, it is necessary to say Y because of a BIOS bug.
2530
2531config APM_DO_ENABLE
2532	bool "Enable PM at boot time"
2533	help
2534	  Enable APM features at boot time. From page 36 of the APM BIOS
2535	  specification: "When disabled, the APM BIOS does not automatically
2536	  power manage devices, enter the Standby State, enter the Suspend
2537	  State, or take power saving steps in response to CPU Idle calls."
2538	  This driver will make CPU Idle calls when Linux is idle (unless this
2539	  feature is turned off -- see "Do CPU IDLE calls", below). This
2540	  should always save battery power, but more complicated APM features
2541	  will be dependent on your BIOS implementation. You may need to turn
2542	  this option off if your computer hangs at boot time when using APM
2543	  support, or if it beeps continuously instead of suspending. Turn
2544	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2545	  T400CDT. This is off by default since most machines do fine without
2546	  this feature.
2547
2548config APM_CPU_IDLE
2549	depends on CPU_IDLE
2550	bool "Make CPU Idle calls when idle"
2551	help
2552	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2553	  On some machines, this can activate improved power savings, such as
2554	  a slowed CPU clock rate, when the machine is idle. These idle calls
2555	  are made after the idle loop has run for some length of time (e.g.,
2556	  333 mS). On some machines, this will cause a hang at boot time or
2557	  whenever the CPU becomes idle. (On machines with more than one CPU,
2558	  this option does nothing.)
2559
2560config APM_DISPLAY_BLANK
2561	bool "Enable console blanking using APM"
2562	help
2563	  Enable console blanking using the APM. Some laptops can use this to
2564	  turn off the LCD backlight when the screen blanker of the Linux
2565	  virtual console blanks the screen. Note that this is only used by
2566	  the virtual console screen blanker, and won't turn off the backlight
2567	  when using the X Window system. This also doesn't have anything to
2568	  do with your VESA-compliant power-saving monitor. Further, this
2569	  option doesn't work for all laptops -- it might not turn off your
2570	  backlight at all, or it might print a lot of errors to the console,
2571	  especially if you are using gpm.
2572
2573config APM_ALLOW_INTS
2574	bool "Allow interrupts during APM BIOS calls"
2575	help
2576	  Normally we disable external interrupts while we are making calls to
2577	  the APM BIOS as a measure to lessen the effects of a badly behaving
2578	  BIOS implementation.  The BIOS should reenable interrupts if it
2579	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2580	  many of the newer IBM Thinkpads.  If you experience hangs when you
2581	  suspend, try setting this to Y.  Otherwise, say N.
2582
2583endif # APM
2584
2585source "drivers/cpufreq/Kconfig"
2586
2587source "drivers/cpuidle/Kconfig"
2588
2589source "drivers/idle/Kconfig"
2590
2591endmenu
2592
2593
2594menu "Bus options (PCI etc.)"
2595
2596choice
2597	prompt "PCI access mode"
2598	depends on X86_32 && PCI
2599	default PCI_GOANY
2600	help
2601	  On PCI systems, the BIOS can be used to detect the PCI devices and
2602	  determine their configuration. However, some old PCI motherboards
2603	  have BIOS bugs and may crash if this is done. Also, some embedded
2604	  PCI-based systems don't have any BIOS at all. Linux can also try to
2605	  detect the PCI hardware directly without using the BIOS.
2606
2607	  With this option, you can specify how Linux should detect the
2608	  PCI devices. If you choose "BIOS", the BIOS will be used,
2609	  if you choose "Direct", the BIOS won't be used, and if you
2610	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2611	  If you choose "Any", the kernel will try MMCONFIG, then the
2612	  direct access method and falls back to the BIOS if that doesn't
2613	  work. If unsure, go with the default, which is "Any".
2614
2615config PCI_GOBIOS
2616	bool "BIOS"
2617
2618config PCI_GOMMCONFIG
2619	bool "MMConfig"
2620
2621config PCI_GODIRECT
2622	bool "Direct"
2623
2624config PCI_GOOLPC
2625	bool "OLPC XO-1"
2626	depends on OLPC
2627
2628config PCI_GOANY
2629	bool "Any"
2630
2631endchoice
2632
2633config PCI_BIOS
2634	def_bool y
2635	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2636
2637# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2638config PCI_DIRECT
2639	def_bool y
2640	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2641
2642config PCI_MMCONFIG
2643	bool "Support mmconfig PCI config space access" if X86_64
2644	default y
2645	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2646	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2647
2648config PCI_OLPC
2649	def_bool y
2650	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2651
2652config PCI_XEN
2653	def_bool y
2654	depends on PCI && XEN
2655
2656config MMCONF_FAM10H
2657	def_bool y
2658	depends on X86_64 && PCI_MMCONFIG && ACPI
2659
2660config PCI_CNB20LE_QUIRK
2661	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2662	depends on PCI
2663	help
2664	  Read the PCI windows out of the CNB20LE host bridge. This allows
2665	  PCI hotplug to work on systems with the CNB20LE chipset which do
2666	  not have ACPI.
2667
2668	  There's no public spec for this chipset, and this functionality
2669	  is known to be incomplete.
2670
2671	  You should say N unless you know you need this.
2672
2673config ISA_BUS
2674	bool "ISA bus support on modern systems" if EXPERT
2675	help
2676	  Expose ISA bus device drivers and options available for selection and
2677	  configuration. Enable this option if your target machine has an ISA
2678	  bus. ISA is an older system, displaced by PCI and newer bus
2679	  architectures -- if your target machine is modern, it probably does
2680	  not have an ISA bus.
2681
2682	  If unsure, say N.
2683
2684# x86_64 have no ISA slots, but can have ISA-style DMA.
2685config ISA_DMA_API
2686	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2687	default y
2688	help
2689	  Enables ISA-style DMA support for devices requiring such controllers.
2690	  If unsure, say Y.
2691
2692if X86_32
2693
2694config ISA
2695	bool "ISA support"
2696	help
2697	  Find out whether you have ISA slots on your motherboard.  ISA is the
2698	  name of a bus system, i.e. the way the CPU talks to the other stuff
2699	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2700	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2701	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2702
2703config SCx200
2704	tristate "NatSemi SCx200 support"
2705	help
2706	  This provides basic support for National Semiconductor's
2707	  (now AMD's) Geode processors.  The driver probes for the
2708	  PCI-IDs of several on-chip devices, so its a good dependency
2709	  for other scx200_* drivers.
2710
2711	  If compiled as a module, the driver is named scx200.
2712
2713config SCx200HR_TIMER
2714	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2715	depends on SCx200
2716	default y
2717	help
2718	  This driver provides a clocksource built upon the on-chip
2719	  27MHz high-resolution timer.  Its also a workaround for
2720	  NSC Geode SC-1100's buggy TSC, which loses time when the
2721	  processor goes idle (as is done by the scheduler).  The
2722	  other workaround is idle=poll boot option.
2723
2724config OLPC
2725	bool "One Laptop Per Child support"
2726	depends on !X86_PAE
2727	select GPIOLIB
2728	select OF
2729	select OF_PROMTREE
2730	select IRQ_DOMAIN
2731	select OLPC_EC
2732	help
2733	  Add support for detecting the unique features of the OLPC
2734	  XO hardware.
2735
2736config OLPC_XO1_PM
2737	bool "OLPC XO-1 Power Management"
2738	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2739	help
2740	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2741
2742config OLPC_XO1_RTC
2743	bool "OLPC XO-1 Real Time Clock"
2744	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2745	help
2746	  Add support for the XO-1 real time clock, which can be used as a
2747	  programmable wakeup source.
2748
2749config OLPC_XO1_SCI
2750	bool "OLPC XO-1 SCI extras"
2751	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2752	depends on INPUT=y
2753	select POWER_SUPPLY
2754	help
2755	  Add support for SCI-based features of the OLPC XO-1 laptop:
2756	   - EC-driven system wakeups
2757	   - Power button
2758	   - Ebook switch
2759	   - Lid switch
2760	   - AC adapter status updates
2761	   - Battery status updates
2762
2763config OLPC_XO15_SCI
2764	bool "OLPC XO-1.5 SCI extras"
2765	depends on OLPC && ACPI
2766	select POWER_SUPPLY
2767	help
2768	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2769	   - EC-driven system wakeups
2770	   - AC adapter status updates
2771	   - Battery status updates
2772
2773config ALIX
2774	bool "PCEngines ALIX System Support (LED setup)"
2775	select GPIOLIB
2776	help
2777	  This option enables system support for the PCEngines ALIX.
2778	  At present this just sets up LEDs for GPIO control on
2779	  ALIX2/3/6 boards.  However, other system specific setup should
2780	  get added here.
2781
2782	  Note: You must still enable the drivers for GPIO and LED support
2783	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2784
2785	  Note: You have to set alix.force=1 for boards with Award BIOS.
2786
2787config NET5501
2788	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2789	select GPIOLIB
2790	help
2791	  This option enables system support for the Soekris Engineering net5501.
2792
2793config GEOS
2794	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2795	select GPIOLIB
2796	depends on DMI
2797	help
2798	  This option enables system support for the Traverse Technologies GEOS.
2799
2800config TS5500
2801	bool "Technologic Systems TS-5500 platform support"
2802	depends on MELAN
2803	select CHECK_SIGNATURE
2804	select NEW_LEDS
2805	select LEDS_CLASS
2806	help
2807	  This option enables system support for the Technologic Systems TS-5500.
2808
2809endif # X86_32
2810
2811config AMD_NB
2812	def_bool y
2813	depends on CPU_SUP_AMD && PCI
2814
2815endmenu
2816
2817
2818menu "Binary Emulations"
2819
2820config IA32_EMULATION
2821	bool "IA32 Emulation"
2822	depends on X86_64
2823	select ARCH_WANT_OLD_COMPAT_IPC
2824	select BINFMT_ELF
2825	select COMPAT_OLD_SIGACTION
2826	help
2827	  Include code to run legacy 32-bit programs under a
2828	  64-bit kernel. You should likely turn this on, unless you're
2829	  100% sure that you don't have any 32-bit programs left.
2830
2831config IA32_AOUT
2832	tristate "IA32 a.out support"
2833	depends on IA32_EMULATION
2834	depends on BROKEN
2835	help
2836	  Support old a.out binaries in the 32bit emulation.
2837
2838config X86_X32
2839	bool "x32 ABI for 64-bit mode"
2840	depends on X86_64
2841	help
2842	  Include code to run binaries for the x32 native 32-bit ABI
2843	  for 64-bit processors.  An x32 process gets access to the
2844	  full 64-bit register file and wide data path while leaving
2845	  pointers at 32 bits for smaller memory footprint.
2846
2847	  You will need a recent binutils (2.22 or later) with
2848	  elf32_x86_64 support enabled to compile a kernel with this
2849	  option set.
2850
2851config COMPAT_32
2852	def_bool y
2853	depends on IA32_EMULATION || X86_32
2854	select HAVE_UID16
2855	select OLD_SIGSUSPEND3
2856
2857config COMPAT
2858	def_bool y
2859	depends on IA32_EMULATION || X86_X32
2860
2861if COMPAT
2862config COMPAT_FOR_U64_ALIGNMENT
2863	def_bool y
2864
2865config SYSVIPC_COMPAT
2866	def_bool y
2867	depends on SYSVIPC
2868endif
2869
2870endmenu
2871
2872
2873config HAVE_ATOMIC_IOMAP
2874	def_bool y
2875	depends on X86_32
2876
2877source "arch/x86/kvm/Kconfig"
2878
2879source "arch/x86/Kconfig.assembler"
2880