xref: /openbmc/linux/arch/x86/Kconfig (revision 827beb77)
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 || (X86_32 && HIGHMEM)
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 && STACK_VALIDATION
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_NUMA_BALANCING	if X86_64
108	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
109	select ARCH_SUPPORTS_LTO_CLANG
110	select ARCH_SUPPORTS_LTO_CLANG_THIN
111	select ARCH_USE_BUILTIN_BSWAP
112	select ARCH_USE_MEMTEST
113	select ARCH_USE_QUEUED_RWLOCKS
114	select ARCH_USE_QUEUED_SPINLOCKS
115	select ARCH_USE_SYM_ANNOTATIONS
116	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
117	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
118	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
119	select ARCH_WANTS_NO_INSTR
120	select ARCH_WANT_HUGE_PMD_SHARE
121	select ARCH_WANT_LD_ORPHAN_WARN
122	select ARCH_WANTS_THP_SWAP		if X86_64
123	select ARCH_HAS_PARANOID_L1D_FLUSH
124	select BUILDTIME_TABLE_SORT
125	select CLKEVT_I8253
126	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
127	select CLOCKSOURCE_WATCHDOG
128	select DCACHE_WORD_ACCESS
129	select DYNAMIC_SIGFRAME
130	select EDAC_ATOMIC_SCRUB
131	select EDAC_SUPPORT
132	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
133	select GENERIC_CLOCKEVENTS_MIN_ADJUST
134	select GENERIC_CMOS_UPDATE
135	select GENERIC_CPU_AUTOPROBE
136	select GENERIC_CPU_VULNERABILITIES
137	select GENERIC_EARLY_IOREMAP
138	select GENERIC_ENTRY
139	select GENERIC_FIND_FIRST_BIT
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_JUMP_LABEL
162	select HAVE_ARCH_JUMP_LABEL_RELATIVE
163	select HAVE_ARCH_KASAN			if X86_64
164	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
165	select HAVE_ARCH_KFENCE
166	select HAVE_ARCH_KGDB
167	select HAVE_ARCH_MMAP_RND_BITS		if MMU
168	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
169	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
170	select HAVE_ARCH_PREL32_RELOCATIONS
171	select HAVE_ARCH_SECCOMP_FILTER
172	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
173	select HAVE_ARCH_STACKLEAK
174	select HAVE_ARCH_TRACEHOOK
175	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
176	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
177	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
178	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
179	select HAVE_ARCH_VMAP_STACK		if X86_64
180	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
181	select HAVE_ARCH_WITHIN_STACK_FRAMES
182	select HAVE_ASM_MODVERSIONS
183	select HAVE_CMPXCHG_DOUBLE
184	select HAVE_CMPXCHG_LOCAL
185	select HAVE_CONTEXT_TRACKING		if X86_64
186	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
187	select HAVE_C_RECORDMCOUNT
188	select HAVE_OBJTOOL_MCOUNT		if STACK_VALIDATION
189	select HAVE_DEBUG_KMEMLEAK
190	select HAVE_DMA_CONTIGUOUS
191	select HAVE_DYNAMIC_FTRACE
192	select HAVE_DYNAMIC_FTRACE_WITH_REGS
193	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
194	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
195	select HAVE_EBPF_JIT
196	select HAVE_EFFICIENT_UNALIGNED_ACCESS
197	select HAVE_EISA
198	select HAVE_EXIT_THREAD
199	select HAVE_FAST_GUP
200	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
201	select HAVE_FTRACE_MCOUNT_RECORD
202	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
203	select HAVE_FUNCTION_TRACER
204	select HAVE_GCC_PLUGINS
205	select HAVE_HW_BREAKPOINT
206	select HAVE_IOREMAP_PROT
207	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
208	select HAVE_IRQ_TIME_ACCOUNTING
209	select HAVE_KERNEL_BZIP2
210	select HAVE_KERNEL_GZIP
211	select HAVE_KERNEL_LZ4
212	select HAVE_KERNEL_LZMA
213	select HAVE_KERNEL_LZO
214	select HAVE_KERNEL_XZ
215	select HAVE_KERNEL_ZSTD
216	select HAVE_KPROBES
217	select HAVE_KPROBES_ON_FTRACE
218	select HAVE_FUNCTION_ERROR_INJECTION
219	select HAVE_KRETPROBES
220	select HAVE_KVM
221	select HAVE_LIVEPATCH			if X86_64
222	select HAVE_MIXED_BREAKPOINTS_REGS
223	select HAVE_MOD_ARCH_SPECIFIC
224	select HAVE_MOVE_PMD
225	select HAVE_MOVE_PUD
226	select HAVE_NMI
227	select HAVE_OPTPROBES
228	select HAVE_PCSPKR_PLATFORM
229	select HAVE_PERF_EVENTS
230	select HAVE_PERF_EVENTS_NMI
231	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
232	select HAVE_PCI
233	select HAVE_PERF_REGS
234	select HAVE_PERF_USER_STACK_DUMP
235	select MMU_GATHER_RCU_TABLE_FREE		if PARAVIRT
236	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
237	select HAVE_REGS_AND_STACK_ACCESS_API
238	select HAVE_RELIABLE_STACKTRACE		if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
239	select HAVE_FUNCTION_ARG_ACCESS_API
240	select HAVE_SOFTIRQ_ON_OWN_STACK
241	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
242	select HAVE_STACK_VALIDATION		if X86_64
243	select HAVE_STATIC_CALL
244	select HAVE_STATIC_CALL_INLINE		if HAVE_STACK_VALIDATION
245	select HAVE_PREEMPT_DYNAMIC
246	select HAVE_RSEQ
247	select HAVE_SYSCALL_TRACEPOINTS
248	select HAVE_UNSTABLE_SCHED_CLOCK
249	select HAVE_USER_RETURN_NOTIFIER
250	select HAVE_GENERIC_VDSO
251	select HOTPLUG_SMT			if SMP
252	select IRQ_FORCED_THREADING
253	select NEED_SG_DMA_LENGTH
254	select PCI_DOMAINS			if PCI
255	select PCI_LOCKLESS_CONFIG		if PCI
256	select PERF_EVENTS
257	select RTC_LIB
258	select RTC_MC146818_LIB
259	select SPARSE_IRQ
260	select SRCU
261	select STACK_VALIDATION			if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
262	select SYSCTL_EXCEPTION_TRACE
263	select THREAD_INFO_IN_TASK
264	select TRACE_IRQFLAGS_SUPPORT
265	select USER_STACKTRACE_SUPPORT
266	select VIRT_TO_BUS
267	select HAVE_ARCH_KCSAN			if X86_64
268	select X86_FEATURE_NAMES		if PROC_FS
269	select PROC_PID_ARCH_STATUS		if PROC_FS
270	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
271
272config INSTRUCTION_DECODER
273	def_bool y
274	depends on KPROBES || PERF_EVENTS || UPROBES
275
276config OUTPUT_FORMAT
277	string
278	default "elf32-i386" if X86_32
279	default "elf64-x86-64" if X86_64
280
281config LOCKDEP_SUPPORT
282	def_bool y
283
284config STACKTRACE_SUPPORT
285	def_bool y
286
287config MMU
288	def_bool y
289
290config ARCH_MMAP_RND_BITS_MIN
291	default 28 if 64BIT
292	default 8
293
294config ARCH_MMAP_RND_BITS_MAX
295	default 32 if 64BIT
296	default 16
297
298config ARCH_MMAP_RND_COMPAT_BITS_MIN
299	default 8
300
301config ARCH_MMAP_RND_COMPAT_BITS_MAX
302	default 16
303
304config SBUS
305	bool
306
307config GENERIC_ISA_DMA
308	def_bool y
309	depends on ISA_DMA_API
310
311config GENERIC_BUG
312	def_bool y
313	depends on BUG
314	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
315
316config GENERIC_BUG_RELATIVE_POINTERS
317	bool
318
319config ARCH_MAY_HAVE_PC_FDC
320	def_bool y
321	depends on ISA_DMA_API
322
323config GENERIC_CALIBRATE_DELAY
324	def_bool y
325
326config ARCH_HAS_CPU_RELAX
327	def_bool y
328
329config ARCH_HAS_FILTER_PGPROT
330	def_bool y
331
332config HAVE_SETUP_PER_CPU_AREA
333	def_bool y
334
335config NEED_PER_CPU_EMBED_FIRST_CHUNK
336	def_bool y
337
338config NEED_PER_CPU_PAGE_FIRST_CHUNK
339	def_bool y
340
341config ARCH_HIBERNATION_POSSIBLE
342	def_bool y
343
344config ARCH_NR_GPIO
345	int
346	default 1024 if X86_64
347	default 512
348
349config ARCH_SUSPEND_POSSIBLE
350	def_bool y
351
352config ARCH_WANT_GENERAL_HUGETLB
353	def_bool y
354
355config AUDIT_ARCH
356	def_bool y if X86_64
357
358config KASAN_SHADOW_OFFSET
359	hex
360	depends on KASAN
361	default 0xdffffc0000000000
362
363config HAVE_INTEL_TXT
364	def_bool y
365	depends on INTEL_IOMMU && ACPI
366
367config X86_32_SMP
368	def_bool y
369	depends on X86_32 && SMP
370
371config X86_64_SMP
372	def_bool y
373	depends on X86_64 && SMP
374
375config ARCH_SUPPORTS_UPROBES
376	def_bool y
377
378config FIX_EARLYCON_MEM
379	def_bool y
380
381config DYNAMIC_PHYSICAL_MASK
382	bool
383
384config PGTABLE_LEVELS
385	int
386	default 5 if X86_5LEVEL
387	default 4 if X86_64
388	default 3 if X86_PAE
389	default 2
390
391config CC_HAS_SANE_STACKPROTECTOR
392	bool
393	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
394	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
395	help
396	   We have to make sure stack protector is unconditionally disabled if
397	   the compiler produces broken code or if it does not let us control
398	   the segment on 32-bit kernels.
399
400menu "Processor type and features"
401
402config SMP
403	bool "Symmetric multi-processing support"
404	help
405	  This enables support for systems with more than one CPU. If you have
406	  a system with only one CPU, say N. If you have a system with more
407	  than one CPU, say Y.
408
409	  If you say N here, the kernel will run on uni- and multiprocessor
410	  machines, but will use only one CPU of a multiprocessor machine. If
411	  you say Y here, the kernel will run on many, but not all,
412	  uniprocessor machines. On a uniprocessor machine, the kernel
413	  will run faster if you say N here.
414
415	  Note that if you say Y here and choose architecture "586" or
416	  "Pentium" under "Processor family", the kernel will not work on 486
417	  architectures. Similarly, multiprocessor kernels for the "PPro"
418	  architecture may not work on all Pentium based boards.
419
420	  People using multiprocessor machines who say Y here should also say
421	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
422	  Management" code will be disabled if you say Y here.
423
424	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
425	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
426	  <http://www.tldp.org/docs.html#howto>.
427
428	  If you don't know what to do here, say N.
429
430config X86_FEATURE_NAMES
431	bool "Processor feature human-readable names" if EMBEDDED
432	default y
433	help
434	  This option compiles in a table of x86 feature bits and corresponding
435	  names.  This is required to support /proc/cpuinfo and a few kernel
436	  messages.  You can disable this to save space, at the expense of
437	  making those few kernel messages show numeric feature bits instead.
438
439	  If in doubt, say Y.
440
441config X86_X2APIC
442	bool "Support x2apic"
443	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
444	help
445	  This enables x2apic support on CPUs that have this feature.
446
447	  This allows 32-bit apic IDs (so it can support very large systems),
448	  and accesses the local apic via MSRs not via mmio.
449
450	  If you don't know what to do here, say N.
451
452config X86_MPPARSE
453	bool "Enable MPS table" if ACPI
454	default y
455	depends on X86_LOCAL_APIC
456	help
457	  For old smp systems that do not have proper acpi support. Newer systems
458	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
459
460config GOLDFISH
461	def_bool y
462	depends on X86_GOLDFISH
463
464config RETPOLINE
465	bool "Avoid speculative indirect branches in kernel"
466	default y
467	help
468	  Compile kernel with the retpoline compiler options to guard against
469	  kernel-to-user data leaks by avoiding speculative indirect
470	  branches. Requires a compiler with -mindirect-branch=thunk-extern
471	  support for full protection. The kernel may run slower.
472
473config X86_CPU_RESCTRL
474	bool "x86 CPU resource control support"
475	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
476	select KERNFS
477	select PROC_CPU_RESCTRL		if PROC_FS
478	help
479	  Enable x86 CPU resource control support.
480
481	  Provide support for the allocation and monitoring of system resources
482	  usage by the CPU.
483
484	  Intel calls this Intel Resource Director Technology
485	  (Intel(R) RDT). More information about RDT can be found in the
486	  Intel x86 Architecture Software Developer Manual.
487
488	  AMD calls this AMD Platform Quality of Service (AMD QoS).
489	  More information about AMD QoS can be found in the AMD64 Technology
490	  Platform Quality of Service Extensions manual.
491
492	  Say N if unsure.
493
494if X86_32
495config X86_BIGSMP
496	bool "Support for big SMP systems with more than 8 CPUs"
497	depends on SMP
498	help
499	  This option is needed for the systems that have more than 8 CPUs.
500
501config X86_EXTENDED_PLATFORM
502	bool "Support for extended (non-PC) x86 platforms"
503	default y
504	help
505	  If you disable this option then the kernel will only support
506	  standard PC platforms. (which covers the vast majority of
507	  systems out there.)
508
509	  If you enable this option then you'll be able to select support
510	  for the following (non-PC) 32 bit x86 platforms:
511		Goldfish (Android emulator)
512		AMD Elan
513		RDC R-321x SoC
514		SGI 320/540 (Visual Workstation)
515		STA2X11-based (e.g. Northville)
516		Moorestown MID devices
517
518	  If you have one of these systems, or if you want to build a
519	  generic distribution kernel, say Y here - otherwise say N.
520endif
521
522if X86_64
523config X86_EXTENDED_PLATFORM
524	bool "Support for extended (non-PC) x86 platforms"
525	default y
526	help
527	  If you disable this option then the kernel will only support
528	  standard PC platforms. (which covers the vast majority of
529	  systems out there.)
530
531	  If you enable this option then you'll be able to select support
532	  for the following (non-PC) 64 bit x86 platforms:
533		Numascale NumaChip
534		ScaleMP vSMP
535		SGI Ultraviolet
536
537	  If you have one of these systems, or if you want to build a
538	  generic distribution kernel, say Y here - otherwise say N.
539endif
540# This is an alphabetically sorted list of 64 bit extended platforms
541# Please maintain the alphabetic order if and when there are additions
542config X86_NUMACHIP
543	bool "Numascale NumaChip"
544	depends on X86_64
545	depends on X86_EXTENDED_PLATFORM
546	depends on NUMA
547	depends on SMP
548	depends on X86_X2APIC
549	depends on PCI_MMCONFIG
550	help
551	  Adds support for Numascale NumaChip large-SMP systems. Needed to
552	  enable more than ~168 cores.
553	  If you don't have one of these, you should say N here.
554
555config X86_VSMP
556	bool "ScaleMP vSMP"
557	select HYPERVISOR_GUEST
558	select PARAVIRT
559	depends on X86_64 && PCI
560	depends on X86_EXTENDED_PLATFORM
561	depends on SMP
562	help
563	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
564	  supposed to run on these EM64T-based machines.  Only choose this option
565	  if you have one of these machines.
566
567config X86_UV
568	bool "SGI Ultraviolet"
569	depends on X86_64
570	depends on X86_EXTENDED_PLATFORM
571	depends on NUMA
572	depends on EFI
573	depends on KEXEC_CORE
574	depends on X86_X2APIC
575	depends on PCI
576	help
577	  This option is needed in order to support SGI Ultraviolet systems.
578	  If you don't have one of these, you should say N here.
579
580# Following is an alphabetically sorted list of 32 bit extended platforms
581# Please maintain the alphabetic order if and when there are additions
582
583config X86_GOLDFISH
584	bool "Goldfish (Virtual Platform)"
585	depends on X86_EXTENDED_PLATFORM
586	help
587	 Enable support for the Goldfish virtual platform used primarily
588	 for Android development. Unless you are building for the Android
589	 Goldfish emulator say N here.
590
591config X86_INTEL_CE
592	bool "CE4100 TV platform"
593	depends on PCI
594	depends on PCI_GODIRECT
595	depends on X86_IO_APIC
596	depends on X86_32
597	depends on X86_EXTENDED_PLATFORM
598	select X86_REBOOTFIXUPS
599	select OF
600	select OF_EARLY_FLATTREE
601	help
602	  Select for the Intel CE media processor (CE4100) SOC.
603	  This option compiles in support for the CE4100 SOC for settop
604	  boxes and media devices.
605
606config X86_INTEL_MID
607	bool "Intel MID platform support"
608	depends on X86_EXTENDED_PLATFORM
609	depends on X86_PLATFORM_DEVICES
610	depends on PCI
611	depends on X86_64 || (PCI_GOANY && X86_32)
612	depends on X86_IO_APIC
613	select I2C
614	select DW_APB_TIMER
615	select INTEL_SCU_PCI
616	help
617	  Select to build a kernel capable of supporting Intel MID (Mobile
618	  Internet Device) platform systems which do not have the PCI legacy
619	  interfaces. If you are building for a PC class system say N here.
620
621	  Intel MID platforms are based on an Intel processor and chipset which
622	  consume less power than most of the x86 derivatives.
623
624config X86_INTEL_QUARK
625	bool "Intel Quark platform support"
626	depends on X86_32
627	depends on X86_EXTENDED_PLATFORM
628	depends on X86_PLATFORM_DEVICES
629	depends on X86_TSC
630	depends on PCI
631	depends on PCI_GOANY
632	depends on X86_IO_APIC
633	select IOSF_MBI
634	select INTEL_IMR
635	select COMMON_CLK
636	help
637	  Select to include support for Quark X1000 SoC.
638	  Say Y here if you have a Quark based system such as the Arduino
639	  compatible Intel Galileo.
640
641config X86_INTEL_LPSS
642	bool "Intel Low Power Subsystem Support"
643	depends on X86 && ACPI && PCI
644	select COMMON_CLK
645	select PINCTRL
646	select IOSF_MBI
647	help
648	  Select to build support for Intel Low Power Subsystem such as
649	  found on Intel Lynxpoint PCH. Selecting this option enables
650	  things like clock tree (common clock framework) and pincontrol
651	  which are needed by the LPSS peripheral drivers.
652
653config X86_AMD_PLATFORM_DEVICE
654	bool "AMD ACPI2Platform devices support"
655	depends on ACPI
656	select COMMON_CLK
657	select PINCTRL
658	help
659	  Select to interpret AMD specific ACPI device to platform device
660	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
661	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
662	  implemented under PINCTRL subsystem.
663
664config IOSF_MBI
665	tristate "Intel SoC IOSF Sideband support for SoC platforms"
666	depends on PCI
667	help
668	  This option enables sideband register access support for Intel SoC
669	  platforms. On these platforms the IOSF sideband is used in lieu of
670	  MSR's for some register accesses, mostly but not limited to thermal
671	  and power. Drivers may query the availability of this device to
672	  determine if they need the sideband in order to work on these
673	  platforms. The sideband is available on the following SoC products.
674	  This list is not meant to be exclusive.
675	   - BayTrail
676	   - Braswell
677	   - Quark
678
679	  You should say Y if you are running a kernel on one of these SoC's.
680
681config IOSF_MBI_DEBUG
682	bool "Enable IOSF sideband access through debugfs"
683	depends on IOSF_MBI && DEBUG_FS
684	help
685	  Select this option to expose the IOSF sideband access registers (MCR,
686	  MDR, MCRX) through debugfs to write and read register information from
687	  different units on the SoC. This is most useful for obtaining device
688	  state information for debug and analysis. As this is a general access
689	  mechanism, users of this option would have specific knowledge of the
690	  device they want to access.
691
692	  If you don't require the option or are in doubt, say N.
693
694config X86_RDC321X
695	bool "RDC R-321x SoC"
696	depends on X86_32
697	depends on X86_EXTENDED_PLATFORM
698	select M486
699	select X86_REBOOTFIXUPS
700	help
701	  This option is needed for RDC R-321x system-on-chip, also known
702	  as R-8610-(G).
703	  If you don't have one of these chips, you should say N here.
704
705config X86_32_NON_STANDARD
706	bool "Support non-standard 32-bit SMP architectures"
707	depends on X86_32 && SMP
708	depends on X86_EXTENDED_PLATFORM
709	help
710	  This option compiles in the bigsmp and STA2X11 default
711	  subarchitectures.  It is intended for a generic binary
712	  kernel. If you select them all, kernel will probe it one by
713	  one and will fallback to default.
714
715# Alphabetically sorted list of Non standard 32 bit platforms
716
717config X86_SUPPORTS_MEMORY_FAILURE
718	def_bool y
719	# MCE code calls memory_failure():
720	depends on X86_MCE
721	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
722	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
723	depends on X86_64 || !SPARSEMEM
724	select ARCH_SUPPORTS_MEMORY_FAILURE
725
726config STA2X11
727	bool "STA2X11 Companion Chip Support"
728	depends on X86_32_NON_STANDARD && PCI
729	select SWIOTLB
730	select MFD_STA2X11
731	select GPIOLIB
732	help
733	  This adds support for boards based on the STA2X11 IO-Hub,
734	  a.k.a. "ConneXt". The chip is used in place of the standard
735	  PC chipset, so all "standard" peripherals are missing. If this
736	  option is selected the kernel will still be able to boot on
737	  standard PC machines.
738
739config X86_32_IRIS
740	tristate "Eurobraille/Iris poweroff module"
741	depends on X86_32
742	help
743	  The Iris machines from EuroBraille do not have APM or ACPI support
744	  to shut themselves down properly.  A special I/O sequence is
745	  needed to do so, which is what this module does at
746	  kernel shutdown.
747
748	  This is only for Iris machines from EuroBraille.
749
750	  If unused, say N.
751
752config SCHED_OMIT_FRAME_POINTER
753	def_bool y
754	prompt "Single-depth WCHAN output"
755	depends on X86
756	help
757	  Calculate simpler /proc/<PID>/wchan values. If this option
758	  is disabled then wchan values will recurse back to the
759	  caller function. This provides more accurate wchan values,
760	  at the expense of slightly more scheduling overhead.
761
762	  If in doubt, say "Y".
763
764menuconfig HYPERVISOR_GUEST
765	bool "Linux guest support"
766	help
767	  Say Y here to enable options for running Linux under various hyper-
768	  visors. This option enables basic hypervisor detection and platform
769	  setup.
770
771	  If you say N, all options in this submenu will be skipped and
772	  disabled, and Linux guest support won't be built in.
773
774if HYPERVISOR_GUEST
775
776config PARAVIRT
777	bool "Enable paravirtualization code"
778	depends on HAVE_STATIC_CALL
779	help
780	  This changes the kernel so it can modify itself when it is run
781	  under a hypervisor, potentially improving performance significantly
782	  over full virtualization.  However, when run without a hypervisor
783	  the kernel is theoretically slower and slightly larger.
784
785config PARAVIRT_XXL
786	bool
787
788config PARAVIRT_DEBUG
789	bool "paravirt-ops debugging"
790	depends on PARAVIRT && DEBUG_KERNEL
791	help
792	  Enable to debug paravirt_ops internals.  Specifically, BUG if
793	  a paravirt_op is missing when it is called.
794
795config PARAVIRT_SPINLOCKS
796	bool "Paravirtualization layer for spinlocks"
797	depends on PARAVIRT && SMP
798	help
799	  Paravirtualized spinlocks allow a pvops backend to replace the
800	  spinlock implementation with something virtualization-friendly
801	  (for example, block the virtual CPU rather than spinning).
802
803	  It has a minimal impact on native kernels and gives a nice performance
804	  benefit on paravirtualized KVM / Xen kernels.
805
806	  If you are unsure how to answer this question, answer Y.
807
808config X86_HV_CALLBACK_VECTOR
809	def_bool n
810
811source "arch/x86/xen/Kconfig"
812
813config KVM_GUEST
814	bool "KVM Guest support (including kvmclock)"
815	depends on PARAVIRT
816	select PARAVIRT_CLOCK
817	select ARCH_CPUIDLE_HALTPOLL
818	select X86_HV_CALLBACK_VECTOR
819	default y
820	help
821	  This option enables various optimizations for running under the KVM
822	  hypervisor. It includes a paravirtualized clock, so that instead
823	  of relying on a PIT (or probably other) emulation by the
824	  underlying device model, the host provides the guest with
825	  timing infrastructure such as time of day, and system time
826
827config ARCH_CPUIDLE_HALTPOLL
828	def_bool n
829	prompt "Disable host haltpoll when loading haltpoll driver"
830	help
831	  If virtualized under KVM, disable host haltpoll.
832
833config PVH
834	bool "Support for running PVH guests"
835	help
836	  This option enables the PVH entry point for guest virtual machines
837	  as specified in the x86/HVM direct boot ABI.
838
839config PARAVIRT_TIME_ACCOUNTING
840	bool "Paravirtual steal time accounting"
841	depends on PARAVIRT
842	help
843	  Select this option to enable fine granularity task steal time
844	  accounting. Time spent executing other tasks in parallel with
845	  the current vCPU is discounted from the vCPU power. To account for
846	  that, there can be a small performance impact.
847
848	  If in doubt, say N here.
849
850config PARAVIRT_CLOCK
851	bool
852
853config JAILHOUSE_GUEST
854	bool "Jailhouse non-root cell support"
855	depends on X86_64 && PCI
856	select X86_PM_TIMER
857	help
858	  This option allows to run Linux as guest in a Jailhouse non-root
859	  cell. You can leave this option disabled if you only want to start
860	  Jailhouse and run Linux afterwards in the root cell.
861
862config ACRN_GUEST
863	bool "ACRN Guest support"
864	depends on X86_64
865	select X86_HV_CALLBACK_VECTOR
866	help
867	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
868	  a flexible, lightweight reference open-source hypervisor, built with
869	  real-time and safety-criticality in mind. It is built for embedded
870	  IOT with small footprint and real-time features. More details can be
871	  found in https://projectacrn.org/.
872
873endif #HYPERVISOR_GUEST
874
875source "arch/x86/Kconfig.cpu"
876
877config HPET_TIMER
878	def_bool X86_64
879	prompt "HPET Timer Support" if X86_32
880	help
881	  Use the IA-PC HPET (High Precision Event Timer) to manage
882	  time in preference to the PIT and RTC, if a HPET is
883	  present.
884	  HPET is the next generation timer replacing legacy 8254s.
885	  The HPET provides a stable time base on SMP
886	  systems, unlike the TSC, but it is more expensive to access,
887	  as it is off-chip.  The interface used is documented
888	  in the HPET spec, revision 1.
889
890	  You can safely choose Y here.  However, HPET will only be
891	  activated if the platform and the BIOS support this feature.
892	  Otherwise the 8254 will be used for timing services.
893
894	  Choose N to continue using the legacy 8254 timer.
895
896config HPET_EMULATE_RTC
897	def_bool y
898	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
899
900# Mark as expert because too many people got it wrong.
901# The code disables itself when not needed.
902config DMI
903	default y
904	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
905	bool "Enable DMI scanning" if EXPERT
906	help
907	  Enabled scanning of DMI to identify machine quirks. Say Y
908	  here unless you have verified that your setup is not
909	  affected by entries in the DMI blacklist. Required by PNP
910	  BIOS code.
911
912config GART_IOMMU
913	bool "Old AMD GART IOMMU support"
914	select DMA_OPS
915	select IOMMU_HELPER
916	select SWIOTLB
917	depends on X86_64 && PCI && AMD_NB
918	help
919	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
920	  GART based hardware IOMMUs.
921
922	  The GART supports full DMA access for devices with 32-bit access
923	  limitations, on systems with more than 3 GB. This is usually needed
924	  for USB, sound, many IDE/SATA chipsets and some other devices.
925
926	  Newer systems typically have a modern AMD IOMMU, supported via
927	  the CONFIG_AMD_IOMMU=y config option.
928
929	  In normal configurations this driver is only active when needed:
930	  there's more than 3 GB of memory and the system contains a
931	  32-bit limited device.
932
933	  If unsure, say Y.
934
935config MAXSMP
936	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
937	depends on X86_64 && SMP && DEBUG_KERNEL
938	select CPUMASK_OFFSTACK
939	help
940	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
941	  If unsure, say N.
942
943#
944# The maximum number of CPUs supported:
945#
946# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
947# and which can be configured interactively in the
948# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
949#
950# The ranges are different on 32-bit and 64-bit kernels, depending on
951# hardware capabilities and scalability features of the kernel.
952#
953# ( If MAXSMP is enabled we just use the highest possible value and disable
954#   interactive configuration. )
955#
956
957config NR_CPUS_RANGE_BEGIN
958	int
959	default NR_CPUS_RANGE_END if MAXSMP
960	default    1 if !SMP
961	default    2
962
963config NR_CPUS_RANGE_END
964	int
965	depends on X86_32
966	default   64 if  SMP &&  X86_BIGSMP
967	default    8 if  SMP && !X86_BIGSMP
968	default    1 if !SMP
969
970config NR_CPUS_RANGE_END
971	int
972	depends on X86_64
973	default 8192 if  SMP && CPUMASK_OFFSTACK
974	default  512 if  SMP && !CPUMASK_OFFSTACK
975	default    1 if !SMP
976
977config NR_CPUS_DEFAULT
978	int
979	depends on X86_32
980	default   32 if  X86_BIGSMP
981	default    8 if  SMP
982	default    1 if !SMP
983
984config NR_CPUS_DEFAULT
985	int
986	depends on X86_64
987	default 8192 if  MAXSMP
988	default   64 if  SMP
989	default    1 if !SMP
990
991config NR_CPUS
992	int "Maximum number of CPUs" if SMP && !MAXSMP
993	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
994	default NR_CPUS_DEFAULT
995	help
996	  This allows you to specify the maximum number of CPUs which this
997	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
998	  supported value is 8192, otherwise the maximum value is 512.  The
999	  minimum value which makes sense is 2.
1000
1001	  This is purely to save memory: each supported CPU adds about 8KB
1002	  to the kernel image.
1003
1004config SCHED_CLUSTER
1005	bool "Cluster scheduler support"
1006	depends on SMP
1007	default y
1008	help
1009	  Cluster scheduler support improves the CPU scheduler's decision
1010	  making when dealing with machines that have clusters of CPUs.
1011	  Cluster usually means a couple of CPUs which are placed closely
1012	  by sharing mid-level caches, last-level cache tags or internal
1013	  busses.
1014
1015config SCHED_SMT
1016	def_bool y if SMP
1017
1018config SCHED_MC
1019	def_bool y
1020	prompt "Multi-core scheduler support"
1021	depends on SMP
1022	help
1023	  Multi-core scheduler support improves the CPU scheduler's decision
1024	  making when dealing with multi-core CPU chips at a cost of slightly
1025	  increased overhead in some places. If unsure say N here.
1026
1027config SCHED_MC_PRIO
1028	bool "CPU core priorities scheduler support"
1029	depends on SCHED_MC && CPU_SUP_INTEL
1030	select X86_INTEL_PSTATE
1031	select CPU_FREQ
1032	default y
1033	help
1034	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1035	  core ordering determined at manufacturing time, which allows
1036	  certain cores to reach higher turbo frequencies (when running
1037	  single threaded workloads) than others.
1038
1039	  Enabling this kernel feature teaches the scheduler about
1040	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1041	  scheduler's CPU selection logic accordingly, so that higher
1042	  overall system performance can be achieved.
1043
1044	  This feature will have no effect on CPUs without this feature.
1045
1046	  If unsure say Y here.
1047
1048config UP_LATE_INIT
1049	def_bool y
1050	depends on !SMP && X86_LOCAL_APIC
1051
1052config X86_UP_APIC
1053	bool "Local APIC support on uniprocessors" if !PCI_MSI
1054	default PCI_MSI
1055	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1056	help
1057	  A local APIC (Advanced Programmable Interrupt Controller) is an
1058	  integrated interrupt controller in the CPU. If you have a single-CPU
1059	  system which has a processor with a local APIC, you can say Y here to
1060	  enable and use it. If you say Y here even though your machine doesn't
1061	  have a local APIC, then the kernel will still run with no slowdown at
1062	  all. The local APIC supports CPU-generated self-interrupts (timer,
1063	  performance counters), and the NMI watchdog which detects hard
1064	  lockups.
1065
1066config X86_UP_IOAPIC
1067	bool "IO-APIC support on uniprocessors"
1068	depends on X86_UP_APIC
1069	help
1070	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1071	  SMP-capable replacement for PC-style interrupt controllers. Most
1072	  SMP systems and many recent uniprocessor systems have one.
1073
1074	  If you have a single-CPU system with an IO-APIC, you can say Y here
1075	  to use it. If you say Y here even though your machine doesn't have
1076	  an IO-APIC, then the kernel will still run with no slowdown at all.
1077
1078config X86_LOCAL_APIC
1079	def_bool y
1080	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1081	select IRQ_DOMAIN_HIERARCHY
1082	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1083
1084config X86_IO_APIC
1085	def_bool y
1086	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1087
1088config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1089	bool "Reroute for broken boot IRQs"
1090	depends on X86_IO_APIC
1091	help
1092	  This option enables a workaround that fixes a source of
1093	  spurious interrupts. This is recommended when threaded
1094	  interrupt handling is used on systems where the generation of
1095	  superfluous "boot interrupts" cannot be disabled.
1096
1097	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1098	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1099	  kernel does during interrupt handling). On chipsets where this
1100	  boot IRQ generation cannot be disabled, this workaround keeps
1101	  the original IRQ line masked so that only the equivalent "boot
1102	  IRQ" is delivered to the CPUs. The workaround also tells the
1103	  kernel to set up the IRQ handler on the boot IRQ line. In this
1104	  way only one interrupt is delivered to the kernel. Otherwise
1105	  the spurious second interrupt may cause the kernel to bring
1106	  down (vital) interrupt lines.
1107
1108	  Only affects "broken" chipsets. Interrupt sharing may be
1109	  increased on these systems.
1110
1111config X86_MCE
1112	bool "Machine Check / overheating reporting"
1113	select GENERIC_ALLOCATOR
1114	default y
1115	help
1116	  Machine Check support allows the processor to notify the
1117	  kernel if it detects a problem (e.g. overheating, data corruption).
1118	  The action the kernel takes depends on the severity of the problem,
1119	  ranging from warning messages to halting the machine.
1120
1121config X86_MCELOG_LEGACY
1122	bool "Support for deprecated /dev/mcelog character device"
1123	depends on X86_MCE
1124	help
1125	  Enable support for /dev/mcelog which is needed by the old mcelog
1126	  userspace logging daemon. Consider switching to the new generation
1127	  rasdaemon solution.
1128
1129config X86_MCE_INTEL
1130	def_bool y
1131	prompt "Intel MCE features"
1132	depends on X86_MCE && X86_LOCAL_APIC
1133	help
1134	   Additional support for intel specific MCE features such as
1135	   the thermal monitor.
1136
1137config X86_MCE_AMD
1138	def_bool y
1139	prompt "AMD MCE features"
1140	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1141	help
1142	   Additional support for AMD specific MCE features such as
1143	   the DRAM Error Threshold.
1144
1145config X86_ANCIENT_MCE
1146	bool "Support for old Pentium 5 / WinChip machine checks"
1147	depends on X86_32 && X86_MCE
1148	help
1149	  Include support for machine check handling on old Pentium 5 or WinChip
1150	  systems. These typically need to be enabled explicitly on the command
1151	  line.
1152
1153config X86_MCE_THRESHOLD
1154	depends on X86_MCE_AMD || X86_MCE_INTEL
1155	def_bool y
1156
1157config X86_MCE_INJECT
1158	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1159	tristate "Machine check injector support"
1160	help
1161	  Provide support for injecting machine checks for testing purposes.
1162	  If you don't know what a machine check is and you don't do kernel
1163	  QA it is safe to say n.
1164
1165source "arch/x86/events/Kconfig"
1166
1167config X86_LEGACY_VM86
1168	bool "Legacy VM86 support"
1169	depends on X86_32
1170	help
1171	  This option allows user programs to put the CPU into V8086
1172	  mode, which is an 80286-era approximation of 16-bit real mode.
1173
1174	  Some very old versions of X and/or vbetool require this option
1175	  for user mode setting.  Similarly, DOSEMU will use it if
1176	  available to accelerate real mode DOS programs.  However, any
1177	  recent version of DOSEMU, X, or vbetool should be fully
1178	  functional even without kernel VM86 support, as they will all
1179	  fall back to software emulation. Nevertheless, if you are using
1180	  a 16-bit DOS program where 16-bit performance matters, vm86
1181	  mode might be faster than emulation and you might want to
1182	  enable this option.
1183
1184	  Note that any app that works on a 64-bit kernel is unlikely to
1185	  need this option, as 64-bit kernels don't, and can't, support
1186	  V8086 mode. This option is also unrelated to 16-bit protected
1187	  mode and is not needed to run most 16-bit programs under Wine.
1188
1189	  Enabling this option increases the complexity of the kernel
1190	  and slows down exception handling a tiny bit.
1191
1192	  If unsure, say N here.
1193
1194config VM86
1195	bool
1196	default X86_LEGACY_VM86
1197
1198config X86_16BIT
1199	bool "Enable support for 16-bit segments" if EXPERT
1200	default y
1201	depends on MODIFY_LDT_SYSCALL
1202	help
1203	  This option is required by programs like Wine to run 16-bit
1204	  protected mode legacy code on x86 processors.  Disabling
1205	  this option saves about 300 bytes on i386, or around 6K text
1206	  plus 16K runtime memory on x86-64,
1207
1208config X86_ESPFIX32
1209	def_bool y
1210	depends on X86_16BIT && X86_32
1211
1212config X86_ESPFIX64
1213	def_bool y
1214	depends on X86_16BIT && X86_64
1215
1216config X86_VSYSCALL_EMULATION
1217	bool "Enable vsyscall emulation" if EXPERT
1218	default y
1219	depends on X86_64
1220	help
1221	 This enables emulation of the legacy vsyscall page.  Disabling
1222	 it is roughly equivalent to booting with vsyscall=none, except
1223	 that it will also disable the helpful warning if a program
1224	 tries to use a vsyscall.  With this option set to N, offending
1225	 programs will just segfault, citing addresses of the form
1226	 0xffffffffff600?00.
1227
1228	 This option is required by many programs built before 2013, and
1229	 care should be used even with newer programs if set to N.
1230
1231	 Disabling this option saves about 7K of kernel size and
1232	 possibly 4K of additional runtime pagetable memory.
1233
1234config X86_IOPL_IOPERM
1235	bool "IOPERM and IOPL Emulation"
1236	default y
1237	help
1238	  This enables the ioperm() and iopl() syscalls which are necessary
1239	  for legacy applications.
1240
1241	  Legacy IOPL support is an overbroad mechanism which allows user
1242	  space aside of accessing all 65536 I/O ports also to disable
1243	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1244	  capabilities and permission from potentially active security
1245	  modules.
1246
1247	  The emulation restricts the functionality of the syscall to
1248	  only allowing the full range I/O port access, but prevents the
1249	  ability to disable interrupts from user space which would be
1250	  granted if the hardware IOPL mechanism would be used.
1251
1252config TOSHIBA
1253	tristate "Toshiba Laptop support"
1254	depends on X86_32
1255	help
1256	  This adds a driver to safely access the System Management Mode of
1257	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1258	  not work on models with a Phoenix BIOS. The System Management Mode
1259	  is used to set the BIOS and power saving options on Toshiba portables.
1260
1261	  For information on utilities to make use of this driver see the
1262	  Toshiba Linux utilities web site at:
1263	  <http://www.buzzard.org.uk/toshiba/>.
1264
1265	  Say Y if you intend to run this kernel on a Toshiba portable.
1266	  Say N otherwise.
1267
1268config I8K
1269	tristate "Dell i8k legacy laptop support"
1270	depends on HWMON
1271	depends on PROC_FS
1272	select SENSORS_DELL_SMM
1273	help
1274	  This option enables legacy /proc/i8k userspace interface in hwmon
1275	  dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1276	  temperature and allows controlling fan speeds of Dell laptops via
1277	  System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1278	  it reports also power and hotkey status. For fan speed control is
1279	  needed userspace package i8kutils.
1280
1281	  Say Y if you intend to run this kernel on old Dell laptops or want to
1282	  use userspace package i8kutils.
1283	  Say N otherwise.
1284
1285config X86_REBOOTFIXUPS
1286	bool "Enable X86 board specific fixups for reboot"
1287	depends on X86_32
1288	help
1289	  This enables chipset and/or board specific fixups to be done
1290	  in order to get reboot to work correctly. This is only needed on
1291	  some combinations of hardware and BIOS. The symptom, for which
1292	  this config is intended, is when reboot ends with a stalled/hung
1293	  system.
1294
1295	  Currently, the only fixup is for the Geode machines using
1296	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1297
1298	  Say Y if you want to enable the fixup. Currently, it's safe to
1299	  enable this option even if you don't need it.
1300	  Say N otherwise.
1301
1302config MICROCODE
1303	bool "CPU microcode loading support"
1304	default y
1305	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1306	help
1307	  If you say Y here, you will be able to update the microcode on
1308	  Intel and AMD processors. The Intel support is for the IA32 family,
1309	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1310	  AMD support is for families 0x10 and later. You will obviously need
1311	  the actual microcode binary data itself which is not shipped with
1312	  the Linux kernel.
1313
1314	  The preferred method to load microcode from a detached initrd is described
1315	  in Documentation/x86/microcode.rst. For that you need to enable
1316	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1317	  initrd for microcode blobs.
1318
1319	  In addition, you can build the microcode into the kernel. For that you
1320	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1321	  config option.
1322
1323config MICROCODE_INTEL
1324	bool "Intel microcode loading support"
1325	depends on MICROCODE
1326	default MICROCODE
1327	help
1328	  This options enables microcode patch loading support for Intel
1329	  processors.
1330
1331	  For the current Intel microcode data package go to
1332	  <https://downloadcenter.intel.com> and search for
1333	  'Linux Processor Microcode Data File'.
1334
1335config MICROCODE_AMD
1336	bool "AMD microcode loading support"
1337	depends on MICROCODE
1338	help
1339	  If you select this option, microcode patch loading support for AMD
1340	  processors will be enabled.
1341
1342config MICROCODE_OLD_INTERFACE
1343	bool "Ancient loading interface (DEPRECATED)"
1344	default n
1345	depends on MICROCODE
1346	help
1347	  DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1348	  which was used by userspace tools like iucode_tool and microcode.ctl.
1349	  It is inadequate because it runs too late to be able to properly
1350	  load microcode on a machine and it needs special tools. Instead, you
1351	  should've switched to the early loading method with the initrd or
1352	  builtin microcode by now: Documentation/x86/microcode.rst
1353
1354config X86_MSR
1355	tristate "/dev/cpu/*/msr - Model-specific register support"
1356	help
1357	  This device gives privileged processes access to the x86
1358	  Model-Specific Registers (MSRs).  It is a character device with
1359	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1360	  MSR accesses are directed to a specific CPU on multi-processor
1361	  systems.
1362
1363config X86_CPUID
1364	tristate "/dev/cpu/*/cpuid - CPU information support"
1365	help
1366	  This device gives processes access to the x86 CPUID instruction to
1367	  be executed on a specific processor.  It is a character device
1368	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1369	  /dev/cpu/31/cpuid.
1370
1371choice
1372	prompt "High Memory Support"
1373	default HIGHMEM4G
1374	depends on X86_32
1375
1376config NOHIGHMEM
1377	bool "off"
1378	help
1379	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1380	  However, the address space of 32-bit x86 processors is only 4
1381	  Gigabytes large. That means that, if you have a large amount of
1382	  physical memory, not all of it can be "permanently mapped" by the
1383	  kernel. The physical memory that's not permanently mapped is called
1384	  "high memory".
1385
1386	  If you are compiling a kernel which will never run on a machine with
1387	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1388	  choice and suitable for most users). This will result in a "3GB/1GB"
1389	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1390	  space and the remaining part of the 4GB virtual memory space is used
1391	  by the kernel to permanently map as much physical memory as
1392	  possible.
1393
1394	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1395	  answer "4GB" here.
1396
1397	  If more than 4 Gigabytes is used then answer "64GB" here. This
1398	  selection turns Intel PAE (Physical Address Extension) mode on.
1399	  PAE implements 3-level paging on IA32 processors. PAE is fully
1400	  supported by Linux, PAE mode is implemented on all recent Intel
1401	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1402	  then the kernel will not boot on CPUs that don't support PAE!
1403
1404	  The actual amount of total physical memory will either be
1405	  auto detected or can be forced by using a kernel command line option
1406	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1407	  your boot loader (lilo or loadlin) about how to pass options to the
1408	  kernel at boot time.)
1409
1410	  If unsure, say "off".
1411
1412config HIGHMEM4G
1413	bool "4GB"
1414	help
1415	  Select this if you have a 32-bit processor and between 1 and 4
1416	  gigabytes of physical RAM.
1417
1418config HIGHMEM64G
1419	bool "64GB"
1420	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1421	select X86_PAE
1422	help
1423	  Select this if you have a 32-bit processor and more than 4
1424	  gigabytes of physical RAM.
1425
1426endchoice
1427
1428choice
1429	prompt "Memory split" if EXPERT
1430	default VMSPLIT_3G
1431	depends on X86_32
1432	help
1433	  Select the desired split between kernel and user memory.
1434
1435	  If the address range available to the kernel is less than the
1436	  physical memory installed, the remaining memory will be available
1437	  as "high memory". Accessing high memory is a little more costly
1438	  than low memory, as it needs to be mapped into the kernel first.
1439	  Note that increasing the kernel address space limits the range
1440	  available to user programs, making the address space there
1441	  tighter.  Selecting anything other than the default 3G/1G split
1442	  will also likely make your kernel incompatible with binary-only
1443	  kernel modules.
1444
1445	  If you are not absolutely sure what you are doing, leave this
1446	  option alone!
1447
1448	config VMSPLIT_3G
1449		bool "3G/1G user/kernel split"
1450	config VMSPLIT_3G_OPT
1451		depends on !X86_PAE
1452		bool "3G/1G user/kernel split (for full 1G low memory)"
1453	config VMSPLIT_2G
1454		bool "2G/2G user/kernel split"
1455	config VMSPLIT_2G_OPT
1456		depends on !X86_PAE
1457		bool "2G/2G user/kernel split (for full 2G low memory)"
1458	config VMSPLIT_1G
1459		bool "1G/3G user/kernel split"
1460endchoice
1461
1462config PAGE_OFFSET
1463	hex
1464	default 0xB0000000 if VMSPLIT_3G_OPT
1465	default 0x80000000 if VMSPLIT_2G
1466	default 0x78000000 if VMSPLIT_2G_OPT
1467	default 0x40000000 if VMSPLIT_1G
1468	default 0xC0000000
1469	depends on X86_32
1470
1471config HIGHMEM
1472	def_bool y
1473	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1474
1475config X86_PAE
1476	bool "PAE (Physical Address Extension) Support"
1477	depends on X86_32 && !HIGHMEM4G
1478	select PHYS_ADDR_T_64BIT
1479	select SWIOTLB
1480	help
1481	  PAE is required for NX support, and furthermore enables
1482	  larger swapspace support for non-overcommit purposes. It
1483	  has the cost of more pagetable lookup overhead, and also
1484	  consumes more pagetable space per process.
1485
1486config X86_5LEVEL
1487	bool "Enable 5-level page tables support"
1488	default y
1489	select DYNAMIC_MEMORY_LAYOUT
1490	select SPARSEMEM_VMEMMAP
1491	depends on X86_64
1492	help
1493	  5-level paging enables access to larger address space:
1494	  upto 128 PiB of virtual address space and 4 PiB of
1495	  physical address space.
1496
1497	  It will be supported by future Intel CPUs.
1498
1499	  A kernel with the option enabled can be booted on machines that
1500	  support 4- or 5-level paging.
1501
1502	  See Documentation/x86/x86_64/5level-paging.rst for more
1503	  information.
1504
1505	  Say N if unsure.
1506
1507config X86_DIRECT_GBPAGES
1508	def_bool y
1509	depends on X86_64
1510	help
1511	  Certain kernel features effectively disable kernel
1512	  linear 1 GB mappings (even if the CPU otherwise
1513	  supports them), so don't confuse the user by printing
1514	  that we have them enabled.
1515
1516config X86_CPA_STATISTICS
1517	bool "Enable statistic for Change Page Attribute"
1518	depends on DEBUG_FS
1519	help
1520	  Expose statistics about the Change Page Attribute mechanism, which
1521	  helps to determine the effectiveness of preserving large and huge
1522	  page mappings when mapping protections are changed.
1523
1524config AMD_MEM_ENCRYPT
1525	bool "AMD Secure Memory Encryption (SME) support"
1526	depends on X86_64 && CPU_SUP_AMD
1527	select DMA_COHERENT_POOL
1528	select DYNAMIC_PHYSICAL_MASK
1529	select ARCH_USE_MEMREMAP_PROT
1530	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1531	select INSTRUCTION_DECODER
1532	select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1533	select ARCH_HAS_CC_PLATFORM
1534	help
1535	  Say yes to enable support for the encryption of system memory.
1536	  This requires an AMD processor that supports Secure Memory
1537	  Encryption (SME).
1538
1539config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1540	bool "Activate AMD Secure Memory Encryption (SME) by default"
1541	depends on AMD_MEM_ENCRYPT
1542	help
1543	  Say yes to have system memory encrypted by default if running on
1544	  an AMD processor that supports Secure Memory Encryption (SME).
1545
1546	  If set to Y, then the encryption of system memory can be
1547	  deactivated with the mem_encrypt=off command line option.
1548
1549	  If set to N, then the encryption of system memory can be
1550	  activated with the mem_encrypt=on command line option.
1551
1552# Common NUMA Features
1553config NUMA
1554	bool "NUMA Memory Allocation and Scheduler Support"
1555	depends on SMP
1556	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1557	default y if X86_BIGSMP
1558	help
1559	  Enable NUMA (Non-Uniform Memory Access) support.
1560
1561	  The kernel will try to allocate memory used by a CPU on the
1562	  local memory controller of the CPU and add some more
1563	  NUMA awareness to the kernel.
1564
1565	  For 64-bit this is recommended if the system is Intel Core i7
1566	  (or later), AMD Opteron, or EM64T NUMA.
1567
1568	  For 32-bit this is only needed if you boot a 32-bit
1569	  kernel on a 64-bit NUMA platform.
1570
1571	  Otherwise, you should say N.
1572
1573config AMD_NUMA
1574	def_bool y
1575	prompt "Old style AMD Opteron NUMA detection"
1576	depends on X86_64 && NUMA && PCI
1577	help
1578	  Enable AMD NUMA node topology detection.  You should say Y here if
1579	  you have a multi processor AMD system. This uses an old method to
1580	  read the NUMA configuration directly from the builtin Northbridge
1581	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1582	  which also takes priority if both are compiled in.
1583
1584config X86_64_ACPI_NUMA
1585	def_bool y
1586	prompt "ACPI NUMA detection"
1587	depends on X86_64 && NUMA && ACPI && PCI
1588	select ACPI_NUMA
1589	help
1590	  Enable ACPI SRAT based node topology detection.
1591
1592config NUMA_EMU
1593	bool "NUMA emulation"
1594	depends on NUMA
1595	help
1596	  Enable NUMA emulation. A flat machine will be split
1597	  into virtual nodes when booted with "numa=fake=N", where N is the
1598	  number of nodes. This is only useful for debugging.
1599
1600config NODES_SHIFT
1601	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1602	range 1 10
1603	default "10" if MAXSMP
1604	default "6" if X86_64
1605	default "3"
1606	depends on NUMA
1607	help
1608	  Specify the maximum number of NUMA Nodes available on the target
1609	  system.  Increases memory reserved to accommodate various tables.
1610
1611config ARCH_FLATMEM_ENABLE
1612	def_bool y
1613	depends on X86_32 && !NUMA
1614
1615config ARCH_SPARSEMEM_ENABLE
1616	def_bool y
1617	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1618	select SPARSEMEM_STATIC if X86_32
1619	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1620
1621config ARCH_SPARSEMEM_DEFAULT
1622	def_bool X86_64 || (NUMA && X86_32)
1623
1624config ARCH_SELECT_MEMORY_MODEL
1625	def_bool y
1626	depends on ARCH_SPARSEMEM_ENABLE
1627
1628config ARCH_MEMORY_PROBE
1629	bool "Enable sysfs memory/probe interface"
1630	depends on X86_64 && MEMORY_HOTPLUG
1631	help
1632	  This option enables a sysfs memory/probe interface for testing.
1633	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1634	  If you are unsure how to answer this question, answer N.
1635
1636config ARCH_PROC_KCORE_TEXT
1637	def_bool y
1638	depends on X86_64 && PROC_KCORE
1639
1640config ILLEGAL_POINTER_VALUE
1641	hex
1642	default 0 if X86_32
1643	default 0xdead000000000000 if X86_64
1644
1645config X86_PMEM_LEGACY_DEVICE
1646	bool
1647
1648config X86_PMEM_LEGACY
1649	tristate "Support non-standard NVDIMMs and ADR protected memory"
1650	depends on PHYS_ADDR_T_64BIT
1651	depends on BLK_DEV
1652	select X86_PMEM_LEGACY_DEVICE
1653	select NUMA_KEEP_MEMINFO if NUMA
1654	select LIBNVDIMM
1655	help
1656	  Treat memory marked using the non-standard e820 type of 12 as used
1657	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1658	  The kernel will offer these regions to the 'pmem' driver so
1659	  they can be used for persistent storage.
1660
1661	  Say Y if unsure.
1662
1663config HIGHPTE
1664	bool "Allocate 3rd-level pagetables from highmem"
1665	depends on HIGHMEM
1666	help
1667	  The VM uses one page table entry for each page of physical memory.
1668	  For systems with a lot of RAM, this can be wasteful of precious
1669	  low memory.  Setting this option will put user-space page table
1670	  entries in high memory.
1671
1672config X86_CHECK_BIOS_CORRUPTION
1673	bool "Check for low memory corruption"
1674	help
1675	  Periodically check for memory corruption in low memory, which
1676	  is suspected to be caused by BIOS.  Even when enabled in the
1677	  configuration, it is disabled at runtime.  Enable it by
1678	  setting "memory_corruption_check=1" on the kernel command
1679	  line.  By default it scans the low 64k of memory every 60
1680	  seconds; see the memory_corruption_check_size and
1681	  memory_corruption_check_period parameters in
1682	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1683
1684	  When enabled with the default parameters, this option has
1685	  almost no overhead, as it reserves a relatively small amount
1686	  of memory and scans it infrequently.  It both detects corruption
1687	  and prevents it from affecting the running system.
1688
1689	  It is, however, intended as a diagnostic tool; if repeatable
1690	  BIOS-originated corruption always affects the same memory,
1691	  you can use memmap= to prevent the kernel from using that
1692	  memory.
1693
1694config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1695	bool "Set the default setting of memory_corruption_check"
1696	depends on X86_CHECK_BIOS_CORRUPTION
1697	default y
1698	help
1699	  Set whether the default state of memory_corruption_check is
1700	  on or off.
1701
1702config MATH_EMULATION
1703	bool
1704	depends on MODIFY_LDT_SYSCALL
1705	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1706	help
1707	  Linux can emulate a math coprocessor (used for floating point
1708	  operations) if you don't have one. 486DX and Pentium processors have
1709	  a math coprocessor built in, 486SX and 386 do not, unless you added
1710	  a 487DX or 387, respectively. (The messages during boot time can
1711	  give you some hints here ["man dmesg"].) Everyone needs either a
1712	  coprocessor or this emulation.
1713
1714	  If you don't have a math coprocessor, you need to say Y here; if you
1715	  say Y here even though you have a coprocessor, the coprocessor will
1716	  be used nevertheless. (This behavior can be changed with the kernel
1717	  command line option "no387", which comes handy if your coprocessor
1718	  is broken. Try "man bootparam" or see the documentation of your boot
1719	  loader (lilo or loadlin) about how to pass options to the kernel at
1720	  boot time.) This means that it is a good idea to say Y here if you
1721	  intend to use this kernel on different machines.
1722
1723	  More information about the internals of the Linux math coprocessor
1724	  emulation can be found in <file:arch/x86/math-emu/README>.
1725
1726	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1727	  kernel, it won't hurt.
1728
1729config MTRR
1730	def_bool y
1731	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1732	help
1733	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1734	  the Memory Type Range Registers (MTRRs) may be used to control
1735	  processor access to memory ranges. This is most useful if you have
1736	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1737	  allows bus write transfers to be combined into a larger transfer
1738	  before bursting over the PCI/AGP bus. This can increase performance
1739	  of image write operations 2.5 times or more. Saying Y here creates a
1740	  /proc/mtrr file which may be used to manipulate your processor's
1741	  MTRRs. Typically the X server should use this.
1742
1743	  This code has a reasonably generic interface so that similar
1744	  control registers on other processors can be easily supported
1745	  as well:
1746
1747	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1748	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1749	  these, the ARRs are used to emulate the MTRRs.
1750	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1751	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1752	  write-combining. All of these processors are supported by this code
1753	  and it makes sense to say Y here if you have one of them.
1754
1755	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1756	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1757	  can lead to all sorts of problems, so it's good to say Y here.
1758
1759	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1760	  just add about 9 KB to your kernel.
1761
1762	  See <file:Documentation/x86/mtrr.rst> for more information.
1763
1764config MTRR_SANITIZER
1765	def_bool y
1766	prompt "MTRR cleanup support"
1767	depends on MTRR
1768	help
1769	  Convert MTRR layout from continuous to discrete, so X drivers can
1770	  add writeback entries.
1771
1772	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1773	  The largest mtrr entry size for a continuous block can be set with
1774	  mtrr_chunk_size.
1775
1776	  If unsure, say Y.
1777
1778config MTRR_SANITIZER_ENABLE_DEFAULT
1779	int "MTRR cleanup enable value (0-1)"
1780	range 0 1
1781	default "0"
1782	depends on MTRR_SANITIZER
1783	help
1784	  Enable mtrr cleanup default value
1785
1786config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1787	int "MTRR cleanup spare reg num (0-7)"
1788	range 0 7
1789	default "1"
1790	depends on MTRR_SANITIZER
1791	help
1792	  mtrr cleanup spare entries default, it can be changed via
1793	  mtrr_spare_reg_nr=N on the kernel command line.
1794
1795config X86_PAT
1796	def_bool y
1797	prompt "x86 PAT support" if EXPERT
1798	depends on MTRR
1799	help
1800	  Use PAT attributes to setup page level cache control.
1801
1802	  PATs are the modern equivalents of MTRRs and are much more
1803	  flexible than MTRRs.
1804
1805	  Say N here if you see bootup problems (boot crash, boot hang,
1806	  spontaneous reboots) or a non-working video driver.
1807
1808	  If unsure, say Y.
1809
1810config ARCH_USES_PG_UNCACHED
1811	def_bool y
1812	depends on X86_PAT
1813
1814config ARCH_RANDOM
1815	def_bool y
1816	prompt "x86 architectural random number generator" if EXPERT
1817	help
1818	  Enable the x86 architectural RDRAND instruction
1819	  (Intel Bull Mountain technology) to generate random numbers.
1820	  If supported, this is a high bandwidth, cryptographically
1821	  secure hardware random number generator.
1822
1823config X86_SMAP
1824	def_bool y
1825	prompt "Supervisor Mode Access Prevention" if EXPERT
1826	help
1827	  Supervisor Mode Access Prevention (SMAP) is a security
1828	  feature in newer Intel processors.  There is a small
1829	  performance cost if this enabled and turned on; there is
1830	  also a small increase in the kernel size if this is enabled.
1831
1832	  If unsure, say Y.
1833
1834config X86_UMIP
1835	def_bool y
1836	prompt "User Mode Instruction Prevention" if EXPERT
1837	help
1838	  User Mode Instruction Prevention (UMIP) is a security feature in
1839	  some x86 processors. If enabled, a general protection fault is
1840	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1841	  executed in user mode. These instructions unnecessarily expose
1842	  information about the hardware state.
1843
1844	  The vast majority of applications do not use these instructions.
1845	  For the very few that do, software emulation is provided in
1846	  specific cases in protected and virtual-8086 modes. Emulated
1847	  results are dummy.
1848
1849config X86_INTEL_MEMORY_PROTECTION_KEYS
1850	prompt "Memory Protection Keys"
1851	def_bool y
1852	# Note: only available in 64-bit mode
1853	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1854	select ARCH_USES_HIGH_VMA_FLAGS
1855	select ARCH_HAS_PKEYS
1856	help
1857	  Memory Protection Keys provides a mechanism for enforcing
1858	  page-based protections, but without requiring modification of the
1859	  page tables when an application changes protection domains.
1860
1861	  For details, see Documentation/core-api/protection-keys.rst
1862
1863	  If unsure, say y.
1864
1865choice
1866	prompt "TSX enable mode"
1867	depends on CPU_SUP_INTEL
1868	default X86_INTEL_TSX_MODE_OFF
1869	help
1870	  Intel's TSX (Transactional Synchronization Extensions) feature
1871	  allows to optimize locking protocols through lock elision which
1872	  can lead to a noticeable performance boost.
1873
1874	  On the other hand it has been shown that TSX can be exploited
1875	  to form side channel attacks (e.g. TAA) and chances are there
1876	  will be more of those attacks discovered in the future.
1877
1878	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1879	  might override this decision by tsx=on the command line parameter.
1880	  Even with TSX enabled, the kernel will attempt to enable the best
1881	  possible TAA mitigation setting depending on the microcode available
1882	  for the particular machine.
1883
1884	  This option allows to set the default tsx mode between tsx=on, =off
1885	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1886	  details.
1887
1888	  Say off if not sure, auto if TSX is in use but it should be used on safe
1889	  platforms or on if TSX is in use and the security aspect of tsx is not
1890	  relevant.
1891
1892config X86_INTEL_TSX_MODE_OFF
1893	bool "off"
1894	help
1895	  TSX is disabled if possible - equals to tsx=off command line parameter.
1896
1897config X86_INTEL_TSX_MODE_ON
1898	bool "on"
1899	help
1900	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1901	  line parameter.
1902
1903config X86_INTEL_TSX_MODE_AUTO
1904	bool "auto"
1905	help
1906	  TSX is enabled on TSX capable HW that is believed to be safe against
1907	  side channel attacks- equals the tsx=auto command line parameter.
1908endchoice
1909
1910config X86_SGX
1911	bool "Software Guard eXtensions (SGX)"
1912	depends on X86_64 && CPU_SUP_INTEL
1913	depends on CRYPTO=y
1914	depends on CRYPTO_SHA256=y
1915	select SRCU
1916	select MMU_NOTIFIER
1917	select NUMA_KEEP_MEMINFO if NUMA
1918	help
1919	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1920	  that can be used by applications to set aside private regions of code
1921	  and data, referred to as enclaves. An enclave's private memory can
1922	  only be accessed by code running within the enclave. Accesses from
1923	  outside the enclave, including other enclaves, are disallowed by
1924	  hardware.
1925
1926	  If unsure, say N.
1927
1928config EFI
1929	bool "EFI runtime service support"
1930	depends on ACPI
1931	select UCS2_STRING
1932	select EFI_RUNTIME_WRAPPERS
1933	help
1934	  This enables the kernel to use EFI runtime services that are
1935	  available (such as the EFI variable services).
1936
1937	  This option is only useful on systems that have EFI firmware.
1938	  In addition, you should use the latest ELILO loader available
1939	  at <http://elilo.sourceforge.net> in order to take advantage
1940	  of EFI runtime services. However, even with this option, the
1941	  resultant kernel should continue to boot on existing non-EFI
1942	  platforms.
1943
1944config EFI_STUB
1945	bool "EFI stub support"
1946	depends on EFI && !X86_USE_3DNOW
1947	depends on $(cc-option,-mabi=ms) || X86_32
1948	select RELOCATABLE
1949	help
1950	  This kernel feature allows a bzImage to be loaded directly
1951	  by EFI firmware without the use of a bootloader.
1952
1953	  See Documentation/admin-guide/efi-stub.rst for more information.
1954
1955config EFI_MIXED
1956	bool "EFI mixed-mode support"
1957	depends on EFI_STUB && X86_64
1958	help
1959	   Enabling this feature allows a 64-bit kernel to be booted
1960	   on a 32-bit firmware, provided that your CPU supports 64-bit
1961	   mode.
1962
1963	   Note that it is not possible to boot a mixed-mode enabled
1964	   kernel via the EFI boot stub - a bootloader that supports
1965	   the EFI handover protocol must be used.
1966
1967	   If unsure, say N.
1968
1969source "kernel/Kconfig.hz"
1970
1971config KEXEC
1972	bool "kexec system call"
1973	select KEXEC_CORE
1974	help
1975	  kexec is a system call that implements the ability to shutdown your
1976	  current kernel, and to start another kernel.  It is like a reboot
1977	  but it is independent of the system firmware.   And like a reboot
1978	  you can start any kernel with it, not just Linux.
1979
1980	  The name comes from the similarity to the exec system call.
1981
1982	  It is an ongoing process to be certain the hardware in a machine
1983	  is properly shutdown, so do not be surprised if this code does not
1984	  initially work for you.  As of this writing the exact hardware
1985	  interface is strongly in flux, so no good recommendation can be
1986	  made.
1987
1988config KEXEC_FILE
1989	bool "kexec file based system call"
1990	select KEXEC_CORE
1991	select BUILD_BIN2C
1992	depends on X86_64
1993	depends on CRYPTO=y
1994	depends on CRYPTO_SHA256=y
1995	help
1996	  This is new version of kexec system call. This system call is
1997	  file based and takes file descriptors as system call argument
1998	  for kernel and initramfs as opposed to list of segments as
1999	  accepted by previous system call.
2000
2001config ARCH_HAS_KEXEC_PURGATORY
2002	def_bool KEXEC_FILE
2003
2004config KEXEC_SIG
2005	bool "Verify kernel signature during kexec_file_load() syscall"
2006	depends on KEXEC_FILE
2007	help
2008
2009	  This option makes the kexec_file_load() syscall check for a valid
2010	  signature of the kernel image.  The image can still be loaded without
2011	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2012	  there's a signature that we can check, then it must be valid.
2013
2014	  In addition to this option, you need to enable signature
2015	  verification for the corresponding kernel image type being
2016	  loaded in order for this to work.
2017
2018config KEXEC_SIG_FORCE
2019	bool "Require a valid signature in kexec_file_load() syscall"
2020	depends on KEXEC_SIG
2021	help
2022	  This option makes kernel signature verification mandatory for
2023	  the kexec_file_load() syscall.
2024
2025config KEXEC_BZIMAGE_VERIFY_SIG
2026	bool "Enable bzImage signature verification support"
2027	depends on KEXEC_SIG
2028	depends on SIGNED_PE_FILE_VERIFICATION
2029	select SYSTEM_TRUSTED_KEYRING
2030	help
2031	  Enable bzImage signature verification support.
2032
2033config CRASH_DUMP
2034	bool "kernel crash dumps"
2035	depends on X86_64 || (X86_32 && HIGHMEM)
2036	help
2037	  Generate crash dump after being started by kexec.
2038	  This should be normally only set in special crash dump kernels
2039	  which are loaded in the main kernel with kexec-tools into
2040	  a specially reserved region and then later executed after
2041	  a crash by kdump/kexec. The crash dump kernel must be compiled
2042	  to a memory address not used by the main kernel or BIOS using
2043	  PHYSICAL_START, or it must be built as a relocatable image
2044	  (CONFIG_RELOCATABLE=y).
2045	  For more details see Documentation/admin-guide/kdump/kdump.rst
2046
2047config KEXEC_JUMP
2048	bool "kexec jump"
2049	depends on KEXEC && HIBERNATION
2050	help
2051	  Jump between original kernel and kexeced kernel and invoke
2052	  code in physical address mode via KEXEC
2053
2054config PHYSICAL_START
2055	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2056	default "0x1000000"
2057	help
2058	  This gives the physical address where the kernel is loaded.
2059
2060	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2061	  bzImage will decompress itself to above physical address and
2062	  run from there. Otherwise, bzImage will run from the address where
2063	  it has been loaded by the boot loader and will ignore above physical
2064	  address.
2065
2066	  In normal kdump cases one does not have to set/change this option
2067	  as now bzImage can be compiled as a completely relocatable image
2068	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2069	  address. This option is mainly useful for the folks who don't want
2070	  to use a bzImage for capturing the crash dump and want to use a
2071	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2072	  to be specifically compiled to run from a specific memory area
2073	  (normally a reserved region) and this option comes handy.
2074
2075	  So if you are using bzImage for capturing the crash dump,
2076	  leave the value here unchanged to 0x1000000 and set
2077	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2078	  for capturing the crash dump change this value to start of
2079	  the reserved region.  In other words, it can be set based on
2080	  the "X" value as specified in the "crashkernel=YM@XM"
2081	  command line boot parameter passed to the panic-ed
2082	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2083	  for more details about crash dumps.
2084
2085	  Usage of bzImage for capturing the crash dump is recommended as
2086	  one does not have to build two kernels. Same kernel can be used
2087	  as production kernel and capture kernel. Above option should have
2088	  gone away after relocatable bzImage support is introduced. But it
2089	  is present because there are users out there who continue to use
2090	  vmlinux for dump capture. This option should go away down the
2091	  line.
2092
2093	  Don't change this unless you know what you are doing.
2094
2095config RELOCATABLE
2096	bool "Build a relocatable kernel"
2097	default y
2098	help
2099	  This builds a kernel image that retains relocation information
2100	  so it can be loaded someplace besides the default 1MB.
2101	  The relocations tend to make the kernel binary about 10% larger,
2102	  but are discarded at runtime.
2103
2104	  One use is for the kexec on panic case where the recovery kernel
2105	  must live at a different physical address than the primary
2106	  kernel.
2107
2108	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2109	  it has been loaded at and the compile time physical address
2110	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2111
2112config RANDOMIZE_BASE
2113	bool "Randomize the address of the kernel image (KASLR)"
2114	depends on RELOCATABLE
2115	default y
2116	help
2117	  In support of Kernel Address Space Layout Randomization (KASLR),
2118	  this randomizes the physical address at which the kernel image
2119	  is decompressed and the virtual address where the kernel
2120	  image is mapped, as a security feature that deters exploit
2121	  attempts relying on knowledge of the location of kernel
2122	  code internals.
2123
2124	  On 64-bit, the kernel physical and virtual addresses are
2125	  randomized separately. The physical address will be anywhere
2126	  between 16MB and the top of physical memory (up to 64TB). The
2127	  virtual address will be randomized from 16MB up to 1GB (9 bits
2128	  of entropy). Note that this also reduces the memory space
2129	  available to kernel modules from 1.5GB to 1GB.
2130
2131	  On 32-bit, the kernel physical and virtual addresses are
2132	  randomized together. They will be randomized from 16MB up to
2133	  512MB (8 bits of entropy).
2134
2135	  Entropy is generated using the RDRAND instruction if it is
2136	  supported. If RDTSC is supported, its value is mixed into
2137	  the entropy pool as well. If neither RDRAND nor RDTSC are
2138	  supported, then entropy is read from the i8254 timer. The
2139	  usable entropy is limited by the kernel being built using
2140	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2141	  minimum of 2MB. As a result, only 10 bits of entropy are
2142	  theoretically possible, but the implementations are further
2143	  limited due to memory layouts.
2144
2145	  If unsure, say Y.
2146
2147# Relocation on x86 needs some additional build support
2148config X86_NEED_RELOCS
2149	def_bool y
2150	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2151
2152config PHYSICAL_ALIGN
2153	hex "Alignment value to which kernel should be aligned"
2154	default "0x200000"
2155	range 0x2000 0x1000000 if X86_32
2156	range 0x200000 0x1000000 if X86_64
2157	help
2158	  This value puts the alignment restrictions on physical address
2159	  where kernel is loaded and run from. Kernel is compiled for an
2160	  address which meets above alignment restriction.
2161
2162	  If bootloader loads the kernel at a non-aligned address and
2163	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2164	  address aligned to above value and run from there.
2165
2166	  If bootloader loads the kernel at a non-aligned address and
2167	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2168	  load address and decompress itself to the address it has been
2169	  compiled for and run from there. The address for which kernel is
2170	  compiled already meets above alignment restrictions. Hence the
2171	  end result is that kernel runs from a physical address meeting
2172	  above alignment restrictions.
2173
2174	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2175	  this value must be a multiple of 0x200000.
2176
2177	  Don't change this unless you know what you are doing.
2178
2179config DYNAMIC_MEMORY_LAYOUT
2180	bool
2181	help
2182	  This option makes base addresses of vmalloc and vmemmap as well as
2183	  __PAGE_OFFSET movable during boot.
2184
2185config RANDOMIZE_MEMORY
2186	bool "Randomize the kernel memory sections"
2187	depends on X86_64
2188	depends on RANDOMIZE_BASE
2189	select DYNAMIC_MEMORY_LAYOUT
2190	default RANDOMIZE_BASE
2191	help
2192	   Randomizes the base virtual address of kernel memory sections
2193	   (physical memory mapping, vmalloc & vmemmap). This security feature
2194	   makes exploits relying on predictable memory locations less reliable.
2195
2196	   The order of allocations remains unchanged. Entropy is generated in
2197	   the same way as RANDOMIZE_BASE. Current implementation in the optimal
2198	   configuration have in average 30,000 different possible virtual
2199	   addresses for each memory section.
2200
2201	   If unsure, say Y.
2202
2203config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2204	hex "Physical memory mapping padding" if EXPERT
2205	depends on RANDOMIZE_MEMORY
2206	default "0xa" if MEMORY_HOTPLUG
2207	default "0x0"
2208	range 0x1 0x40 if MEMORY_HOTPLUG
2209	range 0x0 0x40
2210	help
2211	   Define the padding in terabytes added to the existing physical
2212	   memory size during kernel memory randomization. It is useful
2213	   for memory hotplug support but reduces the entropy available for
2214	   address randomization.
2215
2216	   If unsure, leave at the default value.
2217
2218config HOTPLUG_CPU
2219	def_bool y
2220	depends on SMP
2221
2222config BOOTPARAM_HOTPLUG_CPU0
2223	bool "Set default setting of cpu0_hotpluggable"
2224	depends on HOTPLUG_CPU
2225	help
2226	  Set whether default state of cpu0_hotpluggable is on or off.
2227
2228	  Say Y here to enable CPU0 hotplug by default. If this switch
2229	  is turned on, there is no need to give cpu0_hotplug kernel
2230	  parameter and the CPU0 hotplug feature is enabled by default.
2231
2232	  Please note: there are two known CPU0 dependencies if you want
2233	  to enable the CPU0 hotplug feature either by this switch or by
2234	  cpu0_hotplug kernel parameter.
2235
2236	  First, resume from hibernate or suspend always starts from CPU0.
2237	  So hibernate and suspend are prevented if CPU0 is offline.
2238
2239	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2240	  offline if any interrupt can not migrate out of CPU0. There may
2241	  be other CPU0 dependencies.
2242
2243	  Please make sure the dependencies are under your control before
2244	  you enable this feature.
2245
2246	  Say N if you don't want to enable CPU0 hotplug feature by default.
2247	  You still can enable the CPU0 hotplug feature at boot by kernel
2248	  parameter cpu0_hotplug.
2249
2250config DEBUG_HOTPLUG_CPU0
2251	def_bool n
2252	prompt "Debug CPU0 hotplug"
2253	depends on HOTPLUG_CPU
2254	help
2255	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2256	  soon as possible and boots up userspace with CPU0 offlined. User
2257	  can online CPU0 back after boot time.
2258
2259	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2260	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2261	  compilation or giving cpu0_hotplug kernel parameter at boot.
2262
2263	  If unsure, say N.
2264
2265config COMPAT_VDSO
2266	def_bool n
2267	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2268	depends on COMPAT_32
2269	help
2270	  Certain buggy versions of glibc will crash if they are
2271	  presented with a 32-bit vDSO that is not mapped at the address
2272	  indicated in its segment table.
2273
2274	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2275	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2276	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2277	  the only released version with the bug, but OpenSUSE 9
2278	  contains a buggy "glibc 2.3.2".
2279
2280	  The symptom of the bug is that everything crashes on startup, saying:
2281	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2282
2283	  Saying Y here changes the default value of the vdso32 boot
2284	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2285	  This works around the glibc bug but hurts performance.
2286
2287	  If unsure, say N: if you are compiling your own kernel, you
2288	  are unlikely to be using a buggy version of glibc.
2289
2290choice
2291	prompt "vsyscall table for legacy applications"
2292	depends on X86_64
2293	default LEGACY_VSYSCALL_XONLY
2294	help
2295	  Legacy user code that does not know how to find the vDSO expects
2296	  to be able to issue three syscalls by calling fixed addresses in
2297	  kernel space. Since this location is not randomized with ASLR,
2298	  it can be used to assist security vulnerability exploitation.
2299
2300	  This setting can be changed at boot time via the kernel command
2301	  line parameter vsyscall=[emulate|xonly|none].
2302
2303	  On a system with recent enough glibc (2.14 or newer) and no
2304	  static binaries, you can say None without a performance penalty
2305	  to improve security.
2306
2307	  If unsure, select "Emulate execution only".
2308
2309	config LEGACY_VSYSCALL_EMULATE
2310		bool "Full emulation"
2311		help
2312		  The kernel traps and emulates calls into the fixed vsyscall
2313		  address mapping. This makes the mapping non-executable, but
2314		  it still contains readable known contents, which could be
2315		  used in certain rare security vulnerability exploits. This
2316		  configuration is recommended when using legacy userspace
2317		  that still uses vsyscalls along with legacy binary
2318		  instrumentation tools that require code to be readable.
2319
2320		  An example of this type of legacy userspace is running
2321		  Pin on an old binary that still uses vsyscalls.
2322
2323	config LEGACY_VSYSCALL_XONLY
2324		bool "Emulate execution only"
2325		help
2326		  The kernel traps and emulates calls into the fixed vsyscall
2327		  address mapping and does not allow reads.  This
2328		  configuration is recommended when userspace might use the
2329		  legacy vsyscall area but support for legacy binary
2330		  instrumentation of legacy code is not needed.  It mitigates
2331		  certain uses of the vsyscall area as an ASLR-bypassing
2332		  buffer.
2333
2334	config LEGACY_VSYSCALL_NONE
2335		bool "None"
2336		help
2337		  There will be no vsyscall mapping at all. This will
2338		  eliminate any risk of ASLR bypass due to the vsyscall
2339		  fixed address mapping. Attempts to use the vsyscalls
2340		  will be reported to dmesg, so that either old or
2341		  malicious userspace programs can be identified.
2342
2343endchoice
2344
2345config CMDLINE_BOOL
2346	bool "Built-in kernel command line"
2347	help
2348	  Allow for specifying boot arguments to the kernel at
2349	  build time.  On some systems (e.g. embedded ones), it is
2350	  necessary or convenient to provide some or all of the
2351	  kernel boot arguments with the kernel itself (that is,
2352	  to not rely on the boot loader to provide them.)
2353
2354	  To compile command line arguments into the kernel,
2355	  set this option to 'Y', then fill in the
2356	  boot arguments in CONFIG_CMDLINE.
2357
2358	  Systems with fully functional boot loaders (i.e. non-embedded)
2359	  should leave this option set to 'N'.
2360
2361config CMDLINE
2362	string "Built-in kernel command string"
2363	depends on CMDLINE_BOOL
2364	default ""
2365	help
2366	  Enter arguments here that should be compiled into the kernel
2367	  image and used at boot time.  If the boot loader provides a
2368	  command line at boot time, it is appended to this string to
2369	  form the full kernel command line, when the system boots.
2370
2371	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2372	  change this behavior.
2373
2374	  In most cases, the command line (whether built-in or provided
2375	  by the boot loader) should specify the device for the root
2376	  file system.
2377
2378config CMDLINE_OVERRIDE
2379	bool "Built-in command line overrides boot loader arguments"
2380	depends on CMDLINE_BOOL && CMDLINE != ""
2381	help
2382	  Set this option to 'Y' to have the kernel ignore the boot loader
2383	  command line, and use ONLY the built-in command line.
2384
2385	  This is used to work around broken boot loaders.  This should
2386	  be set to 'N' under normal conditions.
2387
2388config MODIFY_LDT_SYSCALL
2389	bool "Enable the LDT (local descriptor table)" if EXPERT
2390	default y
2391	help
2392	  Linux can allow user programs to install a per-process x86
2393	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2394	  call.  This is required to run 16-bit or segmented code such as
2395	  DOSEMU or some Wine programs.  It is also used by some very old
2396	  threading libraries.
2397
2398	  Enabling this feature adds a small amount of overhead to
2399	  context switches and increases the low-level kernel attack
2400	  surface.  Disabling it removes the modify_ldt(2) system call.
2401
2402	  Saying 'N' here may make sense for embedded or server kernels.
2403
2404config STRICT_SIGALTSTACK_SIZE
2405	bool "Enforce strict size checking for sigaltstack"
2406	depends on DYNAMIC_SIGFRAME
2407	help
2408	  For historical reasons MINSIGSTKSZ is a constant which became
2409	  already too small with AVX512 support. Add a mechanism to
2410	  enforce strict checking of the sigaltstack size against the
2411	  real size of the FPU frame. This option enables the check
2412	  by default. It can also be controlled via the kernel command
2413	  line option 'strict_sas_size' independent of this config
2414	  switch. Enabling it might break existing applications which
2415	  allocate a too small sigaltstack but 'work' because they
2416	  never get a signal delivered.
2417
2418	  Say 'N' unless you want to really enforce this check.
2419
2420source "kernel/livepatch/Kconfig"
2421
2422endmenu
2423
2424config ARCH_HAS_ADD_PAGES
2425	def_bool y
2426	depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2427
2428config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2429	def_bool y
2430
2431config USE_PERCPU_NUMA_NODE_ID
2432	def_bool y
2433	depends on NUMA
2434
2435menu "Power management and ACPI options"
2436
2437config ARCH_HIBERNATION_HEADER
2438	def_bool y
2439	depends on HIBERNATION
2440
2441source "kernel/power/Kconfig"
2442
2443source "drivers/acpi/Kconfig"
2444
2445config X86_APM_BOOT
2446	def_bool y
2447	depends on APM
2448
2449menuconfig APM
2450	tristate "APM (Advanced Power Management) BIOS support"
2451	depends on X86_32 && PM_SLEEP
2452	help
2453	  APM is a BIOS specification for saving power using several different
2454	  techniques. This is mostly useful for battery powered laptops with
2455	  APM compliant BIOSes. If you say Y here, the system time will be
2456	  reset after a RESUME operation, the /proc/apm device will provide
2457	  battery status information, and user-space programs will receive
2458	  notification of APM "events" (e.g. battery status change).
2459
2460	  If you select "Y" here, you can disable actual use of the APM
2461	  BIOS by passing the "apm=off" option to the kernel at boot time.
2462
2463	  Note that the APM support is almost completely disabled for
2464	  machines with more than one CPU.
2465
2466	  In order to use APM, you will need supporting software. For location
2467	  and more information, read <file:Documentation/power/apm-acpi.rst>
2468	  and the Battery Powered Linux mini-HOWTO, available from
2469	  <http://www.tldp.org/docs.html#howto>.
2470
2471	  This driver does not spin down disk drives (see the hdparm(8)
2472	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2473	  VESA-compliant "green" monitors.
2474
2475	  This driver does not support the TI 4000M TravelMate and the ACER
2476	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2477	  desktop machines also don't have compliant BIOSes, and this driver
2478	  may cause those machines to panic during the boot phase.
2479
2480	  Generally, if you don't have a battery in your machine, there isn't
2481	  much point in using this driver and you should say N. If you get
2482	  random kernel OOPSes or reboots that don't seem to be related to
2483	  anything, try disabling/enabling this option (or disabling/enabling
2484	  APM in your BIOS).
2485
2486	  Some other things you should try when experiencing seemingly random,
2487	  "weird" problems:
2488
2489	  1) make sure that you have enough swap space and that it is
2490	  enabled.
2491	  2) pass the "no-hlt" option to the kernel
2492	  3) switch on floating point emulation in the kernel and pass
2493	  the "no387" option to the kernel
2494	  4) pass the "floppy=nodma" option to the kernel
2495	  5) pass the "mem=4M" option to the kernel (thereby disabling
2496	  all but the first 4 MB of RAM)
2497	  6) make sure that the CPU is not over clocked.
2498	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2499	  8) disable the cache from your BIOS settings
2500	  9) install a fan for the video card or exchange video RAM
2501	  10) install a better fan for the CPU
2502	  11) exchange RAM chips
2503	  12) exchange the motherboard.
2504
2505	  To compile this driver as a module, choose M here: the
2506	  module will be called apm.
2507
2508if APM
2509
2510config APM_IGNORE_USER_SUSPEND
2511	bool "Ignore USER SUSPEND"
2512	help
2513	  This option will ignore USER SUSPEND requests. On machines with a
2514	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2515	  series notebooks, it is necessary to say Y because of a BIOS bug.
2516
2517config APM_DO_ENABLE
2518	bool "Enable PM at boot time"
2519	help
2520	  Enable APM features at boot time. From page 36 of the APM BIOS
2521	  specification: "When disabled, the APM BIOS does not automatically
2522	  power manage devices, enter the Standby State, enter the Suspend
2523	  State, or take power saving steps in response to CPU Idle calls."
2524	  This driver will make CPU Idle calls when Linux is idle (unless this
2525	  feature is turned off -- see "Do CPU IDLE calls", below). This
2526	  should always save battery power, but more complicated APM features
2527	  will be dependent on your BIOS implementation. You may need to turn
2528	  this option off if your computer hangs at boot time when using APM
2529	  support, or if it beeps continuously instead of suspending. Turn
2530	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2531	  T400CDT. This is off by default since most machines do fine without
2532	  this feature.
2533
2534config APM_CPU_IDLE
2535	depends on CPU_IDLE
2536	bool "Make CPU Idle calls when idle"
2537	help
2538	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2539	  On some machines, this can activate improved power savings, such as
2540	  a slowed CPU clock rate, when the machine is idle. These idle calls
2541	  are made after the idle loop has run for some length of time (e.g.,
2542	  333 mS). On some machines, this will cause a hang at boot time or
2543	  whenever the CPU becomes idle. (On machines with more than one CPU,
2544	  this option does nothing.)
2545
2546config APM_DISPLAY_BLANK
2547	bool "Enable console blanking using APM"
2548	help
2549	  Enable console blanking using the APM. Some laptops can use this to
2550	  turn off the LCD backlight when the screen blanker of the Linux
2551	  virtual console blanks the screen. Note that this is only used by
2552	  the virtual console screen blanker, and won't turn off the backlight
2553	  when using the X Window system. This also doesn't have anything to
2554	  do with your VESA-compliant power-saving monitor. Further, this
2555	  option doesn't work for all laptops -- it might not turn off your
2556	  backlight at all, or it might print a lot of errors to the console,
2557	  especially if you are using gpm.
2558
2559config APM_ALLOW_INTS
2560	bool "Allow interrupts during APM BIOS calls"
2561	help
2562	  Normally we disable external interrupts while we are making calls to
2563	  the APM BIOS as a measure to lessen the effects of a badly behaving
2564	  BIOS implementation.  The BIOS should reenable interrupts if it
2565	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2566	  many of the newer IBM Thinkpads.  If you experience hangs when you
2567	  suspend, try setting this to Y.  Otherwise, say N.
2568
2569endif # APM
2570
2571source "drivers/cpufreq/Kconfig"
2572
2573source "drivers/cpuidle/Kconfig"
2574
2575source "drivers/idle/Kconfig"
2576
2577endmenu
2578
2579
2580menu "Bus options (PCI etc.)"
2581
2582choice
2583	prompt "PCI access mode"
2584	depends on X86_32 && PCI
2585	default PCI_GOANY
2586	help
2587	  On PCI systems, the BIOS can be used to detect the PCI devices and
2588	  determine their configuration. However, some old PCI motherboards
2589	  have BIOS bugs and may crash if this is done. Also, some embedded
2590	  PCI-based systems don't have any BIOS at all. Linux can also try to
2591	  detect the PCI hardware directly without using the BIOS.
2592
2593	  With this option, you can specify how Linux should detect the
2594	  PCI devices. If you choose "BIOS", the BIOS will be used,
2595	  if you choose "Direct", the BIOS won't be used, and if you
2596	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2597	  If you choose "Any", the kernel will try MMCONFIG, then the
2598	  direct access method and falls back to the BIOS if that doesn't
2599	  work. If unsure, go with the default, which is "Any".
2600
2601config PCI_GOBIOS
2602	bool "BIOS"
2603
2604config PCI_GOMMCONFIG
2605	bool "MMConfig"
2606
2607config PCI_GODIRECT
2608	bool "Direct"
2609
2610config PCI_GOOLPC
2611	bool "OLPC XO-1"
2612	depends on OLPC
2613
2614config PCI_GOANY
2615	bool "Any"
2616
2617endchoice
2618
2619config PCI_BIOS
2620	def_bool y
2621	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2622
2623# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2624config PCI_DIRECT
2625	def_bool y
2626	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2627
2628config PCI_MMCONFIG
2629	bool "Support mmconfig PCI config space access" if X86_64
2630	default y
2631	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2632	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2633
2634config PCI_OLPC
2635	def_bool y
2636	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2637
2638config PCI_XEN
2639	def_bool y
2640	depends on PCI && XEN
2641
2642config MMCONF_FAM10H
2643	def_bool y
2644	depends on X86_64 && PCI_MMCONFIG && ACPI
2645
2646config PCI_CNB20LE_QUIRK
2647	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2648	depends on PCI
2649	help
2650	  Read the PCI windows out of the CNB20LE host bridge. This allows
2651	  PCI hotplug to work on systems with the CNB20LE chipset which do
2652	  not have ACPI.
2653
2654	  There's no public spec for this chipset, and this functionality
2655	  is known to be incomplete.
2656
2657	  You should say N unless you know you need this.
2658
2659config ISA_BUS
2660	bool "ISA bus support on modern systems" if EXPERT
2661	help
2662	  Expose ISA bus device drivers and options available for selection and
2663	  configuration. Enable this option if your target machine has an ISA
2664	  bus. ISA is an older system, displaced by PCI and newer bus
2665	  architectures -- if your target machine is modern, it probably does
2666	  not have an ISA bus.
2667
2668	  If unsure, say N.
2669
2670# x86_64 have no ISA slots, but can have ISA-style DMA.
2671config ISA_DMA_API
2672	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2673	default y
2674	help
2675	  Enables ISA-style DMA support for devices requiring such controllers.
2676	  If unsure, say Y.
2677
2678if X86_32
2679
2680config ISA
2681	bool "ISA support"
2682	help
2683	  Find out whether you have ISA slots on your motherboard.  ISA is the
2684	  name of a bus system, i.e. the way the CPU talks to the other stuff
2685	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2686	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2687	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2688
2689config SCx200
2690	tristate "NatSemi SCx200 support"
2691	help
2692	  This provides basic support for National Semiconductor's
2693	  (now AMD's) Geode processors.  The driver probes for the
2694	  PCI-IDs of several on-chip devices, so its a good dependency
2695	  for other scx200_* drivers.
2696
2697	  If compiled as a module, the driver is named scx200.
2698
2699config SCx200HR_TIMER
2700	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2701	depends on SCx200
2702	default y
2703	help
2704	  This driver provides a clocksource built upon the on-chip
2705	  27MHz high-resolution timer.  Its also a workaround for
2706	  NSC Geode SC-1100's buggy TSC, which loses time when the
2707	  processor goes idle (as is done by the scheduler).  The
2708	  other workaround is idle=poll boot option.
2709
2710config OLPC
2711	bool "One Laptop Per Child support"
2712	depends on !X86_PAE
2713	select GPIOLIB
2714	select OF
2715	select OF_PROMTREE
2716	select IRQ_DOMAIN
2717	select OLPC_EC
2718	help
2719	  Add support for detecting the unique features of the OLPC
2720	  XO hardware.
2721
2722config OLPC_XO1_PM
2723	bool "OLPC XO-1 Power Management"
2724	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2725	help
2726	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2727
2728config OLPC_XO1_RTC
2729	bool "OLPC XO-1 Real Time Clock"
2730	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2731	help
2732	  Add support for the XO-1 real time clock, which can be used as a
2733	  programmable wakeup source.
2734
2735config OLPC_XO1_SCI
2736	bool "OLPC XO-1 SCI extras"
2737	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2738	depends on INPUT=y
2739	select POWER_SUPPLY
2740	help
2741	  Add support for SCI-based features of the OLPC XO-1 laptop:
2742	   - EC-driven system wakeups
2743	   - Power button
2744	   - Ebook switch
2745	   - Lid switch
2746	   - AC adapter status updates
2747	   - Battery status updates
2748
2749config OLPC_XO15_SCI
2750	bool "OLPC XO-1.5 SCI extras"
2751	depends on OLPC && ACPI
2752	select POWER_SUPPLY
2753	help
2754	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2755	   - EC-driven system wakeups
2756	   - AC adapter status updates
2757	   - Battery status updates
2758
2759config ALIX
2760	bool "PCEngines ALIX System Support (LED setup)"
2761	select GPIOLIB
2762	help
2763	  This option enables system support for the PCEngines ALIX.
2764	  At present this just sets up LEDs for GPIO control on
2765	  ALIX2/3/6 boards.  However, other system specific setup should
2766	  get added here.
2767
2768	  Note: You must still enable the drivers for GPIO and LED support
2769	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2770
2771	  Note: You have to set alix.force=1 for boards with Award BIOS.
2772
2773config NET5501
2774	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2775	select GPIOLIB
2776	help
2777	  This option enables system support for the Soekris Engineering net5501.
2778
2779config GEOS
2780	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2781	select GPIOLIB
2782	depends on DMI
2783	help
2784	  This option enables system support for the Traverse Technologies GEOS.
2785
2786config TS5500
2787	bool "Technologic Systems TS-5500 platform support"
2788	depends on MELAN
2789	select CHECK_SIGNATURE
2790	select NEW_LEDS
2791	select LEDS_CLASS
2792	help
2793	  This option enables system support for the Technologic Systems TS-5500.
2794
2795endif # X86_32
2796
2797config AMD_NB
2798	def_bool y
2799	depends on CPU_SUP_AMD && PCI
2800
2801endmenu
2802
2803
2804menu "Binary Emulations"
2805
2806config IA32_EMULATION
2807	bool "IA32 Emulation"
2808	depends on X86_64
2809	select ARCH_WANT_OLD_COMPAT_IPC
2810	select BINFMT_ELF
2811	select COMPAT_OLD_SIGACTION
2812	help
2813	  Include code to run legacy 32-bit programs under a
2814	  64-bit kernel. You should likely turn this on, unless you're
2815	  100% sure that you don't have any 32-bit programs left.
2816
2817config IA32_AOUT
2818	tristate "IA32 a.out support"
2819	depends on IA32_EMULATION
2820	depends on BROKEN
2821	help
2822	  Support old a.out binaries in the 32bit emulation.
2823
2824config X86_X32
2825	bool "x32 ABI for 64-bit mode"
2826	depends on X86_64
2827	help
2828	  Include code to run binaries for the x32 native 32-bit ABI
2829	  for 64-bit processors.  An x32 process gets access to the
2830	  full 64-bit register file and wide data path while leaving
2831	  pointers at 32 bits for smaller memory footprint.
2832
2833	  You will need a recent binutils (2.22 or later) with
2834	  elf32_x86_64 support enabled to compile a kernel with this
2835	  option set.
2836
2837config COMPAT_32
2838	def_bool y
2839	depends on IA32_EMULATION || X86_32
2840	select HAVE_UID16
2841	select OLD_SIGSUSPEND3
2842
2843config COMPAT
2844	def_bool y
2845	depends on IA32_EMULATION || X86_X32
2846
2847if COMPAT
2848config COMPAT_FOR_U64_ALIGNMENT
2849	def_bool y
2850
2851config SYSVIPC_COMPAT
2852	def_bool y
2853	depends on SYSVIPC
2854endif
2855
2856endmenu
2857
2858
2859config HAVE_ATOMIC_IOMAP
2860	def_bool y
2861	depends on X86_32
2862
2863source "arch/x86/kvm/Kconfig"
2864
2865source "arch/x86/Kconfig.assembler"
2866