xref: /linux/arch/x86/Kconfig (revision 0a94608f0f7de9b1135ffea3546afe68eafef57f)
1# SPDX-License-Identifier: GPL-2.0
2# Select 32 or 64 bit
3config 64BIT
4	bool "64-bit kernel" if "$(ARCH)" = "x86"
5	default "$(ARCH)" != "i386"
6	help
7	  Say yes to build a 64-bit kernel - formerly known as x86_64
8	  Say no to build a 32-bit kernel - formerly known as i386
9
10config X86_32
11	def_bool y
12	depends on !64BIT
13	# Options that are inherently 32-bit kernel only:
14	select ARCH_WANT_IPC_PARSE_VERSION
15	select CLKSRC_I8253
16	select CLONE_BACKWARDS
17	select GENERIC_VDSO_32
18	select HAVE_DEBUG_STACKOVERFLOW
19	select KMAP_LOCAL
20	select MODULES_USE_ELF_REL
21	select OLD_SIGACTION
22	select ARCH_SPLIT_ARG64
23
24config X86_64
25	def_bool y
26	depends on 64BIT
27	# Options that are inherently 64-bit kernel only:
28	select ARCH_HAS_GIGANTIC_PAGE
29	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30	select ARCH_USE_CMPXCHG_LOCKREF
31	select HAVE_ARCH_SOFT_DIRTY
32	select MODULES_USE_ELF_RELA
33	select NEED_DMA_MAP_STATE
34	select SWIOTLB
35	select ARCH_HAS_ELFCORE_COMPAT
36	select ZONE_DMA32
37
38config FORCE_DYNAMIC_FTRACE
39	def_bool y
40	depends on X86_32
41	depends on FUNCTION_TRACER
42	select DYNAMIC_FTRACE
43	help
44	 We keep the static function tracing (!DYNAMIC_FTRACE) around
45	 in order to test the non static function tracing in the
46	 generic code, as other architectures still use it. But we
47	 only need to keep it around for x86_64. No need to keep it
48	 for x86_32. For x86_32, force DYNAMIC_FTRACE.
49#
50# Arch settings
51#
52# ( Note that options that are marked 'if X86_64' could in principle be
53#   ported to 32-bit as well. )
54#
55config X86
56	def_bool y
57	#
58	# Note: keep this list sorted alphabetically
59	#
60	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
61	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
62	select ARCH_32BIT_OFF_T			if X86_32
63	select ARCH_CLOCKSOURCE_INIT
64	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
71	select ARCH_HAS_CACHE_LINE_SIZE
72	select ARCH_HAS_CURRENT_STACK_POINTER
73	select ARCH_HAS_DEBUG_VIRTUAL
74	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
75	select ARCH_HAS_DEVMEM_IS_ALLOWED
76	select ARCH_HAS_EARLY_DEBUG		if KGDB
77	select ARCH_HAS_ELF_RANDOMIZE
78	select ARCH_HAS_FAST_MULTIPLIER
79	select ARCH_HAS_FILTER_PGPROT
80	select ARCH_HAS_FORTIFY_SOURCE
81	select ARCH_HAS_GCOV_PROFILE_ALL
82	select ARCH_HAS_KCOV			if X86_64
83	select ARCH_HAS_MEM_ENCRYPT
84	select ARCH_HAS_MEMBARRIER_SYNC_CORE
85	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
86	select ARCH_HAS_PMEM_API		if X86_64
87	select ARCH_HAS_PTE_DEVMAP		if X86_64
88	select ARCH_HAS_PTE_SPECIAL
89	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
90	select ARCH_HAS_COPY_MC			if X86_64
91	select ARCH_HAS_SET_MEMORY
92	select ARCH_HAS_SET_DIRECT_MAP
93	select ARCH_HAS_STRICT_KERNEL_RWX
94	select ARCH_HAS_STRICT_MODULE_RWX
95	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
96	select ARCH_HAS_SYSCALL_WRAPPER
97	select ARCH_HAS_UBSAN_SANITIZE_ALL
98	select ARCH_HAS_DEBUG_WX
99	select ARCH_HAS_ZONE_DMA_SET if EXPERT
100	select ARCH_HAVE_NMI_SAFE_CMPXCHG
101	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
102	select ARCH_MIGHT_HAVE_PC_PARPORT
103	select ARCH_MIGHT_HAVE_PC_SERIO
104	select ARCH_STACKWALK
105	select ARCH_SUPPORTS_ACPI
106	select ARCH_SUPPORTS_ATOMIC_RMW
107	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
108	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
109	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
110	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
111	select ARCH_SUPPORTS_LTO_CLANG
112	select ARCH_SUPPORTS_LTO_CLANG_THIN
113	select ARCH_USE_BUILTIN_BSWAP
114	select ARCH_USE_MEMTEST
115	select ARCH_USE_QUEUED_RWLOCKS
116	select ARCH_USE_QUEUED_SPINLOCKS
117	select ARCH_USE_SYM_ANNOTATIONS
118	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
119	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
120	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
121	select ARCH_WANTS_NO_INSTR
122	select ARCH_WANT_GENERAL_HUGETLB
123	select ARCH_WANT_HUGE_PMD_SHARE
124	select ARCH_WANT_LD_ORPHAN_WARN
125	select ARCH_WANTS_THP_SWAP		if X86_64
126	select ARCH_HAS_PARANOID_L1D_FLUSH
127	select BUILDTIME_TABLE_SORT
128	select CLKEVT_I8253
129	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
130	select CLOCKSOURCE_WATCHDOG
131	select DCACHE_WORD_ACCESS
132	select DYNAMIC_SIGFRAME
133	select EDAC_ATOMIC_SCRUB
134	select EDAC_SUPPORT
135	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
136	select GENERIC_CLOCKEVENTS_MIN_ADJUST
137	select GENERIC_CMOS_UPDATE
138	select GENERIC_CPU_AUTOPROBE
139	select GENERIC_CPU_VULNERABILITIES
140	select GENERIC_EARLY_IOREMAP
141	select GENERIC_ENTRY
142	select GENERIC_IOMAP
143	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
144	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
145	select GENERIC_IRQ_MIGRATION		if SMP
146	select GENERIC_IRQ_PROBE
147	select GENERIC_IRQ_RESERVATION_MODE
148	select GENERIC_IRQ_SHOW
149	select GENERIC_PENDING_IRQ		if SMP
150	select GENERIC_PTDUMP
151	select GENERIC_SMP_IDLE_THREAD
152	select GENERIC_TIME_VSYSCALL
153	select GENERIC_GETTIMEOFDAY
154	select GENERIC_VDSO_TIME_NS
155	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
156	select HARDIRQS_SW_RESEND
157	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
158	select HAVE_ACPI_APEI			if ACPI
159	select HAVE_ACPI_APEI_NMI		if ACPI
160	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
161	select HAVE_ARCH_AUDITSYSCALL
162	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
163	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
164	select HAVE_ARCH_JUMP_LABEL
165	select HAVE_ARCH_JUMP_LABEL_RELATIVE
166	select HAVE_ARCH_KASAN			if X86_64
167	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
168	select HAVE_ARCH_KFENCE
169	select HAVE_ARCH_KGDB
170	select HAVE_ARCH_MMAP_RND_BITS		if MMU
171	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
172	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
173	select HAVE_ARCH_PREL32_RELOCATIONS
174	select HAVE_ARCH_SECCOMP_FILTER
175	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
176	select HAVE_ARCH_STACKLEAK
177	select HAVE_ARCH_TRACEHOOK
178	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
179	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
180	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
181	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
182	select HAVE_ARCH_VMAP_STACK		if X86_64
183	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
184	select HAVE_ARCH_WITHIN_STACK_FRAMES
185	select HAVE_ASM_MODVERSIONS
186	select HAVE_CMPXCHG_DOUBLE
187	select HAVE_CMPXCHG_LOCAL
188	select HAVE_CONTEXT_TRACKING		if X86_64
189	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
190	select HAVE_C_RECORDMCOUNT
191	select HAVE_OBJTOOL_MCOUNT		if STACK_VALIDATION
192	select HAVE_BUILDTIME_MCOUNT_SORT
193	select HAVE_DEBUG_KMEMLEAK
194	select HAVE_DMA_CONTIGUOUS
195	select HAVE_DYNAMIC_FTRACE
196	select HAVE_DYNAMIC_FTRACE_WITH_REGS
197	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
198	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
199	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
200	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
201	select HAVE_EBPF_JIT
202	select HAVE_EFFICIENT_UNALIGNED_ACCESS
203	select HAVE_EISA
204	select HAVE_EXIT_THREAD
205	select HAVE_FAST_GUP
206	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
207	select HAVE_FTRACE_MCOUNT_RECORD
208	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
209	select HAVE_FUNCTION_TRACER
210	select HAVE_GCC_PLUGINS
211	select HAVE_HW_BREAKPOINT
212	select HAVE_IOREMAP_PROT
213	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
214	select HAVE_IRQ_TIME_ACCOUNTING
215	select HAVE_KERNEL_BZIP2
216	select HAVE_KERNEL_GZIP
217	select HAVE_KERNEL_LZ4
218	select HAVE_KERNEL_LZMA
219	select HAVE_KERNEL_LZO
220	select HAVE_KERNEL_XZ
221	select HAVE_KERNEL_ZSTD
222	select HAVE_KPROBES
223	select HAVE_KPROBES_ON_FTRACE
224	select HAVE_FUNCTION_ERROR_INJECTION
225	select HAVE_KRETPROBES
226	select HAVE_RETHOOK
227	select HAVE_KVM
228	select HAVE_LIVEPATCH			if X86_64
229	select HAVE_MIXED_BREAKPOINTS_REGS
230	select HAVE_MOD_ARCH_SPECIFIC
231	select HAVE_MOVE_PMD
232	select HAVE_MOVE_PUD
233	select HAVE_NMI
234	select HAVE_OPTPROBES
235	select HAVE_PCSPKR_PLATFORM
236	select HAVE_PERF_EVENTS
237	select HAVE_PERF_EVENTS_NMI
238	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
239	select HAVE_PCI
240	select HAVE_PERF_REGS
241	select HAVE_PERF_USER_STACK_DUMP
242	select MMU_GATHER_RCU_TABLE_FREE		if PARAVIRT
243	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
244	select HAVE_REGS_AND_STACK_ACCESS_API
245	select HAVE_RELIABLE_STACKTRACE		if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
246	select HAVE_FUNCTION_ARG_ACCESS_API
247	select HAVE_SETUP_PER_CPU_AREA
248	select HAVE_SOFTIRQ_ON_OWN_STACK
249	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
250	select HAVE_STACK_VALIDATION		if X86_64
251	select HAVE_STATIC_CALL
252	select HAVE_STATIC_CALL_INLINE		if HAVE_STACK_VALIDATION
253	select HAVE_PREEMPT_DYNAMIC_CALL
254	select HAVE_RSEQ
255	select HAVE_SYSCALL_TRACEPOINTS
256	select HAVE_UNSTABLE_SCHED_CLOCK
257	select HAVE_USER_RETURN_NOTIFIER
258	select HAVE_GENERIC_VDSO
259	select HOTPLUG_SMT			if SMP
260	select IRQ_FORCED_THREADING
261	select NEED_PER_CPU_EMBED_FIRST_CHUNK
262	select NEED_PER_CPU_PAGE_FIRST_CHUNK
263	select NEED_SG_DMA_LENGTH
264	select PCI_DOMAINS			if PCI
265	select PCI_LOCKLESS_CONFIG		if PCI
266	select PERF_EVENTS
267	select RTC_LIB
268	select RTC_MC146818_LIB
269	select SPARSE_IRQ
270	select SRCU
271	select STACK_VALIDATION			if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
272	select SYSCTL_EXCEPTION_TRACE
273	select THREAD_INFO_IN_TASK
274	select TRACE_IRQFLAGS_SUPPORT
275	select USER_STACKTRACE_SUPPORT
276	select VIRT_TO_BUS
277	select HAVE_ARCH_KCSAN			if X86_64
278	select X86_FEATURE_NAMES		if PROC_FS
279	select PROC_PID_ARCH_STATUS		if PROC_FS
280	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
281	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
282
283config INSTRUCTION_DECODER
284	def_bool y
285	depends on KPROBES || PERF_EVENTS || UPROBES
286
287config OUTPUT_FORMAT
288	string
289	default "elf32-i386" if X86_32
290	default "elf64-x86-64" if X86_64
291
292config LOCKDEP_SUPPORT
293	def_bool y
294
295config STACKTRACE_SUPPORT
296	def_bool y
297
298config MMU
299	def_bool y
300
301config ARCH_MMAP_RND_BITS_MIN
302	default 28 if 64BIT
303	default 8
304
305config ARCH_MMAP_RND_BITS_MAX
306	default 32 if 64BIT
307	default 16
308
309config ARCH_MMAP_RND_COMPAT_BITS_MIN
310	default 8
311
312config ARCH_MMAP_RND_COMPAT_BITS_MAX
313	default 16
314
315config SBUS
316	bool
317
318config GENERIC_ISA_DMA
319	def_bool y
320	depends on ISA_DMA_API
321
322config GENERIC_BUG
323	def_bool y
324	depends on BUG
325	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
326
327config GENERIC_BUG_RELATIVE_POINTERS
328	bool
329
330config ARCH_MAY_HAVE_PC_FDC
331	def_bool y
332	depends on ISA_DMA_API
333
334config GENERIC_CALIBRATE_DELAY
335	def_bool y
336
337config ARCH_HAS_CPU_RELAX
338	def_bool y
339
340config ARCH_HIBERNATION_POSSIBLE
341	def_bool y
342
343config ARCH_NR_GPIO
344	int
345	default 1024 if X86_64
346	default 512
347
348config ARCH_SUSPEND_POSSIBLE
349	def_bool y
350
351config AUDIT_ARCH
352	def_bool y if X86_64
353
354config KASAN_SHADOW_OFFSET
355	hex
356	depends on KASAN
357	default 0xdffffc0000000000
358
359config HAVE_INTEL_TXT
360	def_bool y
361	depends on INTEL_IOMMU && ACPI
362
363config X86_32_SMP
364	def_bool y
365	depends on X86_32 && SMP
366
367config X86_64_SMP
368	def_bool y
369	depends on X86_64 && SMP
370
371config ARCH_SUPPORTS_UPROBES
372	def_bool y
373
374config FIX_EARLYCON_MEM
375	def_bool y
376
377config DYNAMIC_PHYSICAL_MASK
378	bool
379
380config PGTABLE_LEVELS
381	int
382	default 5 if X86_5LEVEL
383	default 4 if X86_64
384	default 3 if X86_PAE
385	default 2
386
387config CC_HAS_SANE_STACKPROTECTOR
388	bool
389	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
390	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
391	help
392	   We have to make sure stack protector is unconditionally disabled if
393	   the compiler produces broken code or if it does not let us control
394	   the segment on 32-bit kernels.
395
396menu "Processor type and features"
397
398config SMP
399	bool "Symmetric multi-processing support"
400	help
401	  This enables support for systems with more than one CPU. If you have
402	  a system with only one CPU, say N. If you have a system with more
403	  than one CPU, say Y.
404
405	  If you say N here, the kernel will run on uni- and multiprocessor
406	  machines, but will use only one CPU of a multiprocessor machine. If
407	  you say Y here, the kernel will run on many, but not all,
408	  uniprocessor machines. On a uniprocessor machine, the kernel
409	  will run faster if you say N here.
410
411	  Note that if you say Y here and choose architecture "586" or
412	  "Pentium" under "Processor family", the kernel will not work on 486
413	  architectures. Similarly, multiprocessor kernels for the "PPro"
414	  architecture may not work on all Pentium based boards.
415
416	  People using multiprocessor machines who say Y here should also say
417	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
418	  Management" code will be disabled if you say Y here.
419
420	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
421	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
422	  <http://www.tldp.org/docs.html#howto>.
423
424	  If you don't know what to do here, say N.
425
426config X86_FEATURE_NAMES
427	bool "Processor feature human-readable names" if EMBEDDED
428	default y
429	help
430	  This option compiles in a table of x86 feature bits and corresponding
431	  names.  This is required to support /proc/cpuinfo and a few kernel
432	  messages.  You can disable this to save space, at the expense of
433	  making those few kernel messages show numeric feature bits instead.
434
435	  If in doubt, say Y.
436
437config X86_X2APIC
438	bool "Support x2apic"
439	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
440	help
441	  This enables x2apic support on CPUs that have this feature.
442
443	  This allows 32-bit apic IDs (so it can support very large systems),
444	  and accesses the local apic via MSRs not via mmio.
445
446	  If you don't know what to do here, say N.
447
448config X86_MPPARSE
449	bool "Enable MPS table" if ACPI
450	default y
451	depends on X86_LOCAL_APIC
452	help
453	  For old smp systems that do not have proper acpi support. Newer systems
454	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
455
456config GOLDFISH
457	def_bool y
458	depends on X86_GOLDFISH
459
460config RETPOLINE
461	bool "Avoid speculative indirect branches in kernel"
462	default y
463	help
464	  Compile kernel with the retpoline compiler options to guard against
465	  kernel-to-user data leaks by avoiding speculative indirect
466	  branches. Requires a compiler with -mindirect-branch=thunk-extern
467	  support for full protection. The kernel may run slower.
468
469config CC_HAS_SLS
470	def_bool $(cc-option,-mharden-sls=all)
471
472config SLS
473	bool "Mitigate Straight-Line-Speculation"
474	depends on CC_HAS_SLS && X86_64
475	default n
476	help
477	  Compile the kernel with straight-line-speculation options to guard
478	  against straight line speculation. The kernel image might be slightly
479	  larger.
480
481config X86_CPU_RESCTRL
482	bool "x86 CPU resource control support"
483	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
484	select KERNFS
485	select PROC_CPU_RESCTRL		if PROC_FS
486	help
487	  Enable x86 CPU resource control support.
488
489	  Provide support for the allocation and monitoring of system resources
490	  usage by the CPU.
491
492	  Intel calls this Intel Resource Director Technology
493	  (Intel(R) RDT). More information about RDT can be found in the
494	  Intel x86 Architecture Software Developer Manual.
495
496	  AMD calls this AMD Platform Quality of Service (AMD QoS).
497	  More information about AMD QoS can be found in the AMD64 Technology
498	  Platform Quality of Service Extensions manual.
499
500	  Say N if unsure.
501
502if X86_32
503config X86_BIGSMP
504	bool "Support for big SMP systems with more than 8 CPUs"
505	depends on SMP
506	help
507	  This option is needed for the systems that have more than 8 CPUs.
508
509config X86_EXTENDED_PLATFORM
510	bool "Support for extended (non-PC) x86 platforms"
511	default y
512	help
513	  If you disable this option then the kernel will only support
514	  standard PC platforms. (which covers the vast majority of
515	  systems out there.)
516
517	  If you enable this option then you'll be able to select support
518	  for the following (non-PC) 32 bit x86 platforms:
519		Goldfish (Android emulator)
520		AMD Elan
521		RDC R-321x SoC
522		SGI 320/540 (Visual Workstation)
523		STA2X11-based (e.g. Northville)
524		Moorestown MID devices
525
526	  If you have one of these systems, or if you want to build a
527	  generic distribution kernel, say Y here - otherwise say N.
528endif
529
530if X86_64
531config X86_EXTENDED_PLATFORM
532	bool "Support for extended (non-PC) x86 platforms"
533	default y
534	help
535	  If you disable this option then the kernel will only support
536	  standard PC platforms. (which covers the vast majority of
537	  systems out there.)
538
539	  If you enable this option then you'll be able to select support
540	  for the following (non-PC) 64 bit x86 platforms:
541		Numascale NumaChip
542		ScaleMP vSMP
543		SGI Ultraviolet
544
545	  If you have one of these systems, or if you want to build a
546	  generic distribution kernel, say Y here - otherwise say N.
547endif
548# This is an alphabetically sorted list of 64 bit extended platforms
549# Please maintain the alphabetic order if and when there are additions
550config X86_NUMACHIP
551	bool "Numascale NumaChip"
552	depends on X86_64
553	depends on X86_EXTENDED_PLATFORM
554	depends on NUMA
555	depends on SMP
556	depends on X86_X2APIC
557	depends on PCI_MMCONFIG
558	help
559	  Adds support for Numascale NumaChip large-SMP systems. Needed to
560	  enable more than ~168 cores.
561	  If you don't have one of these, you should say N here.
562
563config X86_VSMP
564	bool "ScaleMP vSMP"
565	select HYPERVISOR_GUEST
566	select PARAVIRT
567	depends on X86_64 && PCI
568	depends on X86_EXTENDED_PLATFORM
569	depends on SMP
570	help
571	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
572	  supposed to run on these EM64T-based machines.  Only choose this option
573	  if you have one of these machines.
574
575config X86_UV
576	bool "SGI Ultraviolet"
577	depends on X86_64
578	depends on X86_EXTENDED_PLATFORM
579	depends on NUMA
580	depends on EFI
581	depends on KEXEC_CORE
582	depends on X86_X2APIC
583	depends on PCI
584	help
585	  This option is needed in order to support SGI Ultraviolet systems.
586	  If you don't have one of these, you should say N here.
587
588# Following is an alphabetically sorted list of 32 bit extended platforms
589# Please maintain the alphabetic order if and when there are additions
590
591config X86_GOLDFISH
592	bool "Goldfish (Virtual Platform)"
593	depends on X86_EXTENDED_PLATFORM
594	help
595	 Enable support for the Goldfish virtual platform used primarily
596	 for Android development. Unless you are building for the Android
597	 Goldfish emulator say N here.
598
599config X86_INTEL_CE
600	bool "CE4100 TV platform"
601	depends on PCI
602	depends on PCI_GODIRECT
603	depends on X86_IO_APIC
604	depends on X86_32
605	depends on X86_EXTENDED_PLATFORM
606	select X86_REBOOTFIXUPS
607	select OF
608	select OF_EARLY_FLATTREE
609	help
610	  Select for the Intel CE media processor (CE4100) SOC.
611	  This option compiles in support for the CE4100 SOC for settop
612	  boxes and media devices.
613
614config X86_INTEL_MID
615	bool "Intel MID platform support"
616	depends on X86_EXTENDED_PLATFORM
617	depends on X86_PLATFORM_DEVICES
618	depends on PCI
619	depends on X86_64 || (PCI_GOANY && X86_32)
620	depends on X86_IO_APIC
621	select I2C
622	select DW_APB_TIMER
623	select INTEL_SCU_PCI
624	help
625	  Select to build a kernel capable of supporting Intel MID (Mobile
626	  Internet Device) platform systems which do not have the PCI legacy
627	  interfaces. If you are building for a PC class system say N here.
628
629	  Intel MID platforms are based on an Intel processor and chipset which
630	  consume less power than most of the x86 derivatives.
631
632config X86_INTEL_QUARK
633	bool "Intel Quark platform support"
634	depends on X86_32
635	depends on X86_EXTENDED_PLATFORM
636	depends on X86_PLATFORM_DEVICES
637	depends on X86_TSC
638	depends on PCI
639	depends on PCI_GOANY
640	depends on X86_IO_APIC
641	select IOSF_MBI
642	select INTEL_IMR
643	select COMMON_CLK
644	help
645	  Select to include support for Quark X1000 SoC.
646	  Say Y here if you have a Quark based system such as the Arduino
647	  compatible Intel Galileo.
648
649config X86_INTEL_LPSS
650	bool "Intel Low Power Subsystem Support"
651	depends on X86 && ACPI && PCI
652	select COMMON_CLK
653	select PINCTRL
654	select IOSF_MBI
655	help
656	  Select to build support for Intel Low Power Subsystem such as
657	  found on Intel Lynxpoint PCH. Selecting this option enables
658	  things like clock tree (common clock framework) and pincontrol
659	  which are needed by the LPSS peripheral drivers.
660
661config X86_AMD_PLATFORM_DEVICE
662	bool "AMD ACPI2Platform devices support"
663	depends on ACPI
664	select COMMON_CLK
665	select PINCTRL
666	help
667	  Select to interpret AMD specific ACPI device to platform device
668	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
669	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
670	  implemented under PINCTRL subsystem.
671
672config IOSF_MBI
673	tristate "Intel SoC IOSF Sideband support for SoC platforms"
674	depends on PCI
675	help
676	  This option enables sideband register access support for Intel SoC
677	  platforms. On these platforms the IOSF sideband is used in lieu of
678	  MSR's for some register accesses, mostly but not limited to thermal
679	  and power. Drivers may query the availability of this device to
680	  determine if they need the sideband in order to work on these
681	  platforms. The sideband is available on the following SoC products.
682	  This list is not meant to be exclusive.
683	   - BayTrail
684	   - Braswell
685	   - Quark
686
687	  You should say Y if you are running a kernel on one of these SoC's.
688
689config IOSF_MBI_DEBUG
690	bool "Enable IOSF sideband access through debugfs"
691	depends on IOSF_MBI && DEBUG_FS
692	help
693	  Select this option to expose the IOSF sideband access registers (MCR,
694	  MDR, MCRX) through debugfs to write and read register information from
695	  different units on the SoC. This is most useful for obtaining device
696	  state information for debug and analysis. As this is a general access
697	  mechanism, users of this option would have specific knowledge of the
698	  device they want to access.
699
700	  If you don't require the option or are in doubt, say N.
701
702config X86_RDC321X
703	bool "RDC R-321x SoC"
704	depends on X86_32
705	depends on X86_EXTENDED_PLATFORM
706	select M486
707	select X86_REBOOTFIXUPS
708	help
709	  This option is needed for RDC R-321x system-on-chip, also known
710	  as R-8610-(G).
711	  If you don't have one of these chips, you should say N here.
712
713config X86_32_NON_STANDARD
714	bool "Support non-standard 32-bit SMP architectures"
715	depends on X86_32 && SMP
716	depends on X86_EXTENDED_PLATFORM
717	help
718	  This option compiles in the bigsmp and STA2X11 default
719	  subarchitectures.  It is intended for a generic binary
720	  kernel. If you select them all, kernel will probe it one by
721	  one and will fallback to default.
722
723# Alphabetically sorted list of Non standard 32 bit platforms
724
725config X86_SUPPORTS_MEMORY_FAILURE
726	def_bool y
727	# MCE code calls memory_failure():
728	depends on X86_MCE
729	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
730	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
731	depends on X86_64 || !SPARSEMEM
732	select ARCH_SUPPORTS_MEMORY_FAILURE
733
734config STA2X11
735	bool "STA2X11 Companion Chip Support"
736	depends on X86_32_NON_STANDARD && PCI
737	select SWIOTLB
738	select MFD_STA2X11
739	select GPIOLIB
740	help
741	  This adds support for boards based on the STA2X11 IO-Hub,
742	  a.k.a. "ConneXt". The chip is used in place of the standard
743	  PC chipset, so all "standard" peripherals are missing. If this
744	  option is selected the kernel will still be able to boot on
745	  standard PC machines.
746
747config X86_32_IRIS
748	tristate "Eurobraille/Iris poweroff module"
749	depends on X86_32
750	help
751	  The Iris machines from EuroBraille do not have APM or ACPI support
752	  to shut themselves down properly.  A special I/O sequence is
753	  needed to do so, which is what this module does at
754	  kernel shutdown.
755
756	  This is only for Iris machines from EuroBraille.
757
758	  If unused, say N.
759
760config SCHED_OMIT_FRAME_POINTER
761	def_bool y
762	prompt "Single-depth WCHAN output"
763	depends on X86
764	help
765	  Calculate simpler /proc/<PID>/wchan values. If this option
766	  is disabled then wchan values will recurse back to the
767	  caller function. This provides more accurate wchan values,
768	  at the expense of slightly more scheduling overhead.
769
770	  If in doubt, say "Y".
771
772menuconfig HYPERVISOR_GUEST
773	bool "Linux guest support"
774	help
775	  Say Y here to enable options for running Linux under various hyper-
776	  visors. This option enables basic hypervisor detection and platform
777	  setup.
778
779	  If you say N, all options in this submenu will be skipped and
780	  disabled, and Linux guest support won't be built in.
781
782if HYPERVISOR_GUEST
783
784config PARAVIRT
785	bool "Enable paravirtualization code"
786	depends on HAVE_STATIC_CALL
787	help
788	  This changes the kernel so it can modify itself when it is run
789	  under a hypervisor, potentially improving performance significantly
790	  over full virtualization.  However, when run without a hypervisor
791	  the kernel is theoretically slower and slightly larger.
792
793config PARAVIRT_XXL
794	bool
795
796config PARAVIRT_DEBUG
797	bool "paravirt-ops debugging"
798	depends on PARAVIRT && DEBUG_KERNEL
799	help
800	  Enable to debug paravirt_ops internals.  Specifically, BUG if
801	  a paravirt_op is missing when it is called.
802
803config PARAVIRT_SPINLOCKS
804	bool "Paravirtualization layer for spinlocks"
805	depends on PARAVIRT && SMP
806	help
807	  Paravirtualized spinlocks allow a pvops backend to replace the
808	  spinlock implementation with something virtualization-friendly
809	  (for example, block the virtual CPU rather than spinning).
810
811	  It has a minimal impact on native kernels and gives a nice performance
812	  benefit on paravirtualized KVM / Xen kernels.
813
814	  If you are unsure how to answer this question, answer Y.
815
816config X86_HV_CALLBACK_VECTOR
817	def_bool n
818
819source "arch/x86/xen/Kconfig"
820
821config KVM_GUEST
822	bool "KVM Guest support (including kvmclock)"
823	depends on PARAVIRT
824	select PARAVIRT_CLOCK
825	select ARCH_CPUIDLE_HALTPOLL
826	select X86_HV_CALLBACK_VECTOR
827	default y
828	help
829	  This option enables various optimizations for running under the KVM
830	  hypervisor. It includes a paravirtualized clock, so that instead
831	  of relying on a PIT (or probably other) emulation by the
832	  underlying device model, the host provides the guest with
833	  timing infrastructure such as time of day, and system time
834
835config ARCH_CPUIDLE_HALTPOLL
836	def_bool n
837	prompt "Disable host haltpoll when loading haltpoll driver"
838	help
839	  If virtualized under KVM, disable host haltpoll.
840
841config PVH
842	bool "Support for running PVH guests"
843	help
844	  This option enables the PVH entry point for guest virtual machines
845	  as specified in the x86/HVM direct boot ABI.
846
847config PARAVIRT_TIME_ACCOUNTING
848	bool "Paravirtual steal time accounting"
849	depends on PARAVIRT
850	help
851	  Select this option to enable fine granularity task steal time
852	  accounting. Time spent executing other tasks in parallel with
853	  the current vCPU is discounted from the vCPU power. To account for
854	  that, there can be a small performance impact.
855
856	  If in doubt, say N here.
857
858config PARAVIRT_CLOCK
859	bool
860
861config JAILHOUSE_GUEST
862	bool "Jailhouse non-root cell support"
863	depends on X86_64 && PCI
864	select X86_PM_TIMER
865	help
866	  This option allows to run Linux as guest in a Jailhouse non-root
867	  cell. You can leave this option disabled if you only want to start
868	  Jailhouse and run Linux afterwards in the root cell.
869
870config ACRN_GUEST
871	bool "ACRN Guest support"
872	depends on X86_64
873	select X86_HV_CALLBACK_VECTOR
874	help
875	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
876	  a flexible, lightweight reference open-source hypervisor, built with
877	  real-time and safety-criticality in mind. It is built for embedded
878	  IOT with small footprint and real-time features. More details can be
879	  found in https://projectacrn.org/.
880
881endif #HYPERVISOR_GUEST
882
883source "arch/x86/Kconfig.cpu"
884
885config HPET_TIMER
886	def_bool X86_64
887	prompt "HPET Timer Support" if X86_32
888	help
889	  Use the IA-PC HPET (High Precision Event Timer) to manage
890	  time in preference to the PIT and RTC, if a HPET is
891	  present.
892	  HPET is the next generation timer replacing legacy 8254s.
893	  The HPET provides a stable time base on SMP
894	  systems, unlike the TSC, but it is more expensive to access,
895	  as it is off-chip.  The interface used is documented
896	  in the HPET spec, revision 1.
897
898	  You can safely choose Y here.  However, HPET will only be
899	  activated if the platform and the BIOS support this feature.
900	  Otherwise the 8254 will be used for timing services.
901
902	  Choose N to continue using the legacy 8254 timer.
903
904config HPET_EMULATE_RTC
905	def_bool y
906	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
907
908# Mark as expert because too many people got it wrong.
909# The code disables itself when not needed.
910config DMI
911	default y
912	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
913	bool "Enable DMI scanning" if EXPERT
914	help
915	  Enabled scanning of DMI to identify machine quirks. Say Y
916	  here unless you have verified that your setup is not
917	  affected by entries in the DMI blacklist. Required by PNP
918	  BIOS code.
919
920config GART_IOMMU
921	bool "Old AMD GART IOMMU support"
922	select DMA_OPS
923	select IOMMU_HELPER
924	select SWIOTLB
925	depends on X86_64 && PCI && AMD_NB
926	help
927	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
928	  GART based hardware IOMMUs.
929
930	  The GART supports full DMA access for devices with 32-bit access
931	  limitations, on systems with more than 3 GB. This is usually needed
932	  for USB, sound, many IDE/SATA chipsets and some other devices.
933
934	  Newer systems typically have a modern AMD IOMMU, supported via
935	  the CONFIG_AMD_IOMMU=y config option.
936
937	  In normal configurations this driver is only active when needed:
938	  there's more than 3 GB of memory and the system contains a
939	  32-bit limited device.
940
941	  If unsure, say Y.
942
943config BOOT_VESA_SUPPORT
944	bool
945	help
946	  If true, at least one selected framebuffer driver can take advantage
947	  of VESA video modes set at an early boot stage via the vga= parameter.
948
949config MAXSMP
950	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
951	depends on X86_64 && SMP && DEBUG_KERNEL
952	select CPUMASK_OFFSTACK
953	help
954	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
955	  If unsure, say N.
956
957#
958# The maximum number of CPUs supported:
959#
960# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
961# and which can be configured interactively in the
962# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
963#
964# The ranges are different on 32-bit and 64-bit kernels, depending on
965# hardware capabilities and scalability features of the kernel.
966#
967# ( If MAXSMP is enabled we just use the highest possible value and disable
968#   interactive configuration. )
969#
970
971config NR_CPUS_RANGE_BEGIN
972	int
973	default NR_CPUS_RANGE_END if MAXSMP
974	default    1 if !SMP
975	default    2
976
977config NR_CPUS_RANGE_END
978	int
979	depends on X86_32
980	default   64 if  SMP &&  X86_BIGSMP
981	default    8 if  SMP && !X86_BIGSMP
982	default    1 if !SMP
983
984config NR_CPUS_RANGE_END
985	int
986	depends on X86_64
987	default 8192 if  SMP && CPUMASK_OFFSTACK
988	default  512 if  SMP && !CPUMASK_OFFSTACK
989	default    1 if !SMP
990
991config NR_CPUS_DEFAULT
992	int
993	depends on X86_32
994	default   32 if  X86_BIGSMP
995	default    8 if  SMP
996	default    1 if !SMP
997
998config NR_CPUS_DEFAULT
999	int
1000	depends on X86_64
1001	default 8192 if  MAXSMP
1002	default   64 if  SMP
1003	default    1 if !SMP
1004
1005config NR_CPUS
1006	int "Maximum number of CPUs" if SMP && !MAXSMP
1007	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1008	default NR_CPUS_DEFAULT
1009	help
1010	  This allows you to specify the maximum number of CPUs which this
1011	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1012	  supported value is 8192, otherwise the maximum value is 512.  The
1013	  minimum value which makes sense is 2.
1014
1015	  This is purely to save memory: each supported CPU adds about 8KB
1016	  to the kernel image.
1017
1018config SCHED_CLUSTER
1019	bool "Cluster scheduler support"
1020	depends on SMP
1021	default y
1022	help
1023	  Cluster scheduler support improves the CPU scheduler's decision
1024	  making when dealing with machines that have clusters of CPUs.
1025	  Cluster usually means a couple of CPUs which are placed closely
1026	  by sharing mid-level caches, last-level cache tags or internal
1027	  busses.
1028
1029config SCHED_SMT
1030	def_bool y if SMP
1031
1032config SCHED_MC
1033	def_bool y
1034	prompt "Multi-core scheduler support"
1035	depends on SMP
1036	help
1037	  Multi-core scheduler support improves the CPU scheduler's decision
1038	  making when dealing with multi-core CPU chips at a cost of slightly
1039	  increased overhead in some places. If unsure say N here.
1040
1041config SCHED_MC_PRIO
1042	bool "CPU core priorities scheduler support"
1043	depends on SCHED_MC && CPU_SUP_INTEL
1044	select X86_INTEL_PSTATE
1045	select CPU_FREQ
1046	default y
1047	help
1048	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1049	  core ordering determined at manufacturing time, which allows
1050	  certain cores to reach higher turbo frequencies (when running
1051	  single threaded workloads) than others.
1052
1053	  Enabling this kernel feature teaches the scheduler about
1054	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1055	  scheduler's CPU selection logic accordingly, so that higher
1056	  overall system performance can be achieved.
1057
1058	  This feature will have no effect on CPUs without this feature.
1059
1060	  If unsure say Y here.
1061
1062config UP_LATE_INIT
1063	def_bool y
1064	depends on !SMP && X86_LOCAL_APIC
1065
1066config X86_UP_APIC
1067	bool "Local APIC support on uniprocessors" if !PCI_MSI
1068	default PCI_MSI
1069	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1070	help
1071	  A local APIC (Advanced Programmable Interrupt Controller) is an
1072	  integrated interrupt controller in the CPU. If you have a single-CPU
1073	  system which has a processor with a local APIC, you can say Y here to
1074	  enable and use it. If you say Y here even though your machine doesn't
1075	  have a local APIC, then the kernel will still run with no slowdown at
1076	  all. The local APIC supports CPU-generated self-interrupts (timer,
1077	  performance counters), and the NMI watchdog which detects hard
1078	  lockups.
1079
1080config X86_UP_IOAPIC
1081	bool "IO-APIC support on uniprocessors"
1082	depends on X86_UP_APIC
1083	help
1084	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1085	  SMP-capable replacement for PC-style interrupt controllers. Most
1086	  SMP systems and many recent uniprocessor systems have one.
1087
1088	  If you have a single-CPU system with an IO-APIC, you can say Y here
1089	  to use it. If you say Y here even though your machine doesn't have
1090	  an IO-APIC, then the kernel will still run with no slowdown at all.
1091
1092config X86_LOCAL_APIC
1093	def_bool y
1094	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1095	select IRQ_DOMAIN_HIERARCHY
1096	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1097
1098config X86_IO_APIC
1099	def_bool y
1100	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1101
1102config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1103	bool "Reroute for broken boot IRQs"
1104	depends on X86_IO_APIC
1105	help
1106	  This option enables a workaround that fixes a source of
1107	  spurious interrupts. This is recommended when threaded
1108	  interrupt handling is used on systems where the generation of
1109	  superfluous "boot interrupts" cannot be disabled.
1110
1111	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1112	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1113	  kernel does during interrupt handling). On chipsets where this
1114	  boot IRQ generation cannot be disabled, this workaround keeps
1115	  the original IRQ line masked so that only the equivalent "boot
1116	  IRQ" is delivered to the CPUs. The workaround also tells the
1117	  kernel to set up the IRQ handler on the boot IRQ line. In this
1118	  way only one interrupt is delivered to the kernel. Otherwise
1119	  the spurious second interrupt may cause the kernel to bring
1120	  down (vital) interrupt lines.
1121
1122	  Only affects "broken" chipsets. Interrupt sharing may be
1123	  increased on these systems.
1124
1125config X86_MCE
1126	bool "Machine Check / overheating reporting"
1127	select GENERIC_ALLOCATOR
1128	default y
1129	help
1130	  Machine Check support allows the processor to notify the
1131	  kernel if it detects a problem (e.g. overheating, data corruption).
1132	  The action the kernel takes depends on the severity of the problem,
1133	  ranging from warning messages to halting the machine.
1134
1135config X86_MCELOG_LEGACY
1136	bool "Support for deprecated /dev/mcelog character device"
1137	depends on X86_MCE
1138	help
1139	  Enable support for /dev/mcelog which is needed by the old mcelog
1140	  userspace logging daemon. Consider switching to the new generation
1141	  rasdaemon solution.
1142
1143config X86_MCE_INTEL
1144	def_bool y
1145	prompt "Intel MCE features"
1146	depends on X86_MCE && X86_LOCAL_APIC
1147	help
1148	   Additional support for intel specific MCE features such as
1149	   the thermal monitor.
1150
1151config X86_MCE_AMD
1152	def_bool y
1153	prompt "AMD MCE features"
1154	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1155	help
1156	   Additional support for AMD specific MCE features such as
1157	   the DRAM Error Threshold.
1158
1159config X86_ANCIENT_MCE
1160	bool "Support for old Pentium 5 / WinChip machine checks"
1161	depends on X86_32 && X86_MCE
1162	help
1163	  Include support for machine check handling on old Pentium 5 or WinChip
1164	  systems. These typically need to be enabled explicitly on the command
1165	  line.
1166
1167config X86_MCE_THRESHOLD
1168	depends on X86_MCE_AMD || X86_MCE_INTEL
1169	def_bool y
1170
1171config X86_MCE_INJECT
1172	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1173	tristate "Machine check injector support"
1174	help
1175	  Provide support for injecting machine checks for testing purposes.
1176	  If you don't know what a machine check is and you don't do kernel
1177	  QA it is safe to say n.
1178
1179source "arch/x86/events/Kconfig"
1180
1181config X86_LEGACY_VM86
1182	bool "Legacy VM86 support"
1183	depends on X86_32
1184	help
1185	  This option allows user programs to put the CPU into V8086
1186	  mode, which is an 80286-era approximation of 16-bit real mode.
1187
1188	  Some very old versions of X and/or vbetool require this option
1189	  for user mode setting.  Similarly, DOSEMU will use it if
1190	  available to accelerate real mode DOS programs.  However, any
1191	  recent version of DOSEMU, X, or vbetool should be fully
1192	  functional even without kernel VM86 support, as they will all
1193	  fall back to software emulation. Nevertheless, if you are using
1194	  a 16-bit DOS program where 16-bit performance matters, vm86
1195	  mode might be faster than emulation and you might want to
1196	  enable this option.
1197
1198	  Note that any app that works on a 64-bit kernel is unlikely to
1199	  need this option, as 64-bit kernels don't, and can't, support
1200	  V8086 mode. This option is also unrelated to 16-bit protected
1201	  mode and is not needed to run most 16-bit programs under Wine.
1202
1203	  Enabling this option increases the complexity of the kernel
1204	  and slows down exception handling a tiny bit.
1205
1206	  If unsure, say N here.
1207
1208config VM86
1209	bool
1210	default X86_LEGACY_VM86
1211
1212config X86_16BIT
1213	bool "Enable support for 16-bit segments" if EXPERT
1214	default y
1215	depends on MODIFY_LDT_SYSCALL
1216	help
1217	  This option is required by programs like Wine to run 16-bit
1218	  protected mode legacy code on x86 processors.  Disabling
1219	  this option saves about 300 bytes on i386, or around 6K text
1220	  plus 16K runtime memory on x86-64,
1221
1222config X86_ESPFIX32
1223	def_bool y
1224	depends on X86_16BIT && X86_32
1225
1226config X86_ESPFIX64
1227	def_bool y
1228	depends on X86_16BIT && X86_64
1229
1230config X86_VSYSCALL_EMULATION
1231	bool "Enable vsyscall emulation" if EXPERT
1232	default y
1233	depends on X86_64
1234	help
1235	 This enables emulation of the legacy vsyscall page.  Disabling
1236	 it is roughly equivalent to booting with vsyscall=none, except
1237	 that it will also disable the helpful warning if a program
1238	 tries to use a vsyscall.  With this option set to N, offending
1239	 programs will just segfault, citing addresses of the form
1240	 0xffffffffff600?00.
1241
1242	 This option is required by many programs built before 2013, and
1243	 care should be used even with newer programs if set to N.
1244
1245	 Disabling this option saves about 7K of kernel size and
1246	 possibly 4K of additional runtime pagetable memory.
1247
1248config X86_IOPL_IOPERM
1249	bool "IOPERM and IOPL Emulation"
1250	default y
1251	help
1252	  This enables the ioperm() and iopl() syscalls which are necessary
1253	  for legacy applications.
1254
1255	  Legacy IOPL support is an overbroad mechanism which allows user
1256	  space aside of accessing all 65536 I/O ports also to disable
1257	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1258	  capabilities and permission from potentially active security
1259	  modules.
1260
1261	  The emulation restricts the functionality of the syscall to
1262	  only allowing the full range I/O port access, but prevents the
1263	  ability to disable interrupts from user space which would be
1264	  granted if the hardware IOPL mechanism would be used.
1265
1266config TOSHIBA
1267	tristate "Toshiba Laptop support"
1268	depends on X86_32
1269	help
1270	  This adds a driver to safely access the System Management Mode of
1271	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1272	  not work on models with a Phoenix BIOS. The System Management Mode
1273	  is used to set the BIOS and power saving options on Toshiba portables.
1274
1275	  For information on utilities to make use of this driver see the
1276	  Toshiba Linux utilities web site at:
1277	  <http://www.buzzard.org.uk/toshiba/>.
1278
1279	  Say Y if you intend to run this kernel on a Toshiba portable.
1280	  Say N otherwise.
1281
1282config X86_REBOOTFIXUPS
1283	bool "Enable X86 board specific fixups for reboot"
1284	depends on X86_32
1285	help
1286	  This enables chipset and/or board specific fixups to be done
1287	  in order to get reboot to work correctly. This is only needed on
1288	  some combinations of hardware and BIOS. The symptom, for which
1289	  this config is intended, is when reboot ends with a stalled/hung
1290	  system.
1291
1292	  Currently, the only fixup is for the Geode machines using
1293	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1294
1295	  Say Y if you want to enable the fixup. Currently, it's safe to
1296	  enable this option even if you don't need it.
1297	  Say N otherwise.
1298
1299config MICROCODE
1300	bool "CPU microcode loading support"
1301	default y
1302	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1303	help
1304	  If you say Y here, you will be able to update the microcode on
1305	  Intel and AMD processors. The Intel support is for the IA32 family,
1306	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1307	  AMD support is for families 0x10 and later. You will obviously need
1308	  the actual microcode binary data itself which is not shipped with
1309	  the Linux kernel.
1310
1311	  The preferred method to load microcode from a detached initrd is described
1312	  in Documentation/x86/microcode.rst. For that you need to enable
1313	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1314	  initrd for microcode blobs.
1315
1316	  In addition, you can build the microcode into the kernel. For that you
1317	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1318	  config option.
1319
1320config MICROCODE_INTEL
1321	bool "Intel microcode loading support"
1322	depends on MICROCODE
1323	default MICROCODE
1324	help
1325	  This options enables microcode patch loading support for Intel
1326	  processors.
1327
1328	  For the current Intel microcode data package go to
1329	  <https://downloadcenter.intel.com> and search for
1330	  'Linux Processor Microcode Data File'.
1331
1332config MICROCODE_AMD
1333	bool "AMD microcode loading support"
1334	depends on MICROCODE
1335	help
1336	  If you select this option, microcode patch loading support for AMD
1337	  processors will be enabled.
1338
1339config MICROCODE_OLD_INTERFACE
1340	bool "Ancient loading interface (DEPRECATED)"
1341	default n
1342	depends on MICROCODE
1343	help
1344	  DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1345	  which was used by userspace tools like iucode_tool and microcode.ctl.
1346	  It is inadequate because it runs too late to be able to properly
1347	  load microcode on a machine and it needs special tools. Instead, you
1348	  should've switched to the early loading method with the initrd or
1349	  builtin microcode by now: Documentation/x86/microcode.rst
1350
1351config X86_MSR
1352	tristate "/dev/cpu/*/msr - Model-specific register support"
1353	help
1354	  This device gives privileged processes access to the x86
1355	  Model-Specific Registers (MSRs).  It is a character device with
1356	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1357	  MSR accesses are directed to a specific CPU on multi-processor
1358	  systems.
1359
1360config X86_CPUID
1361	tristate "/dev/cpu/*/cpuid - CPU information support"
1362	help
1363	  This device gives processes access to the x86 CPUID instruction to
1364	  be executed on a specific processor.  It is a character device
1365	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1366	  /dev/cpu/31/cpuid.
1367
1368choice
1369	prompt "High Memory Support"
1370	default HIGHMEM4G
1371	depends on X86_32
1372
1373config NOHIGHMEM
1374	bool "off"
1375	help
1376	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1377	  However, the address space of 32-bit x86 processors is only 4
1378	  Gigabytes large. That means that, if you have a large amount of
1379	  physical memory, not all of it can be "permanently mapped" by the
1380	  kernel. The physical memory that's not permanently mapped is called
1381	  "high memory".
1382
1383	  If you are compiling a kernel which will never run on a machine with
1384	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1385	  choice and suitable for most users). This will result in a "3GB/1GB"
1386	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1387	  space and the remaining part of the 4GB virtual memory space is used
1388	  by the kernel to permanently map as much physical memory as
1389	  possible.
1390
1391	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1392	  answer "4GB" here.
1393
1394	  If more than 4 Gigabytes is used then answer "64GB" here. This
1395	  selection turns Intel PAE (Physical Address Extension) mode on.
1396	  PAE implements 3-level paging on IA32 processors. PAE is fully
1397	  supported by Linux, PAE mode is implemented on all recent Intel
1398	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1399	  then the kernel will not boot on CPUs that don't support PAE!
1400
1401	  The actual amount of total physical memory will either be
1402	  auto detected or can be forced by using a kernel command line option
1403	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1404	  your boot loader (lilo or loadlin) about how to pass options to the
1405	  kernel at boot time.)
1406
1407	  If unsure, say "off".
1408
1409config HIGHMEM4G
1410	bool "4GB"
1411	help
1412	  Select this if you have a 32-bit processor and between 1 and 4
1413	  gigabytes of physical RAM.
1414
1415config HIGHMEM64G
1416	bool "64GB"
1417	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1418	select X86_PAE
1419	help
1420	  Select this if you have a 32-bit processor and more than 4
1421	  gigabytes of physical RAM.
1422
1423endchoice
1424
1425choice
1426	prompt "Memory split" if EXPERT
1427	default VMSPLIT_3G
1428	depends on X86_32
1429	help
1430	  Select the desired split between kernel and user memory.
1431
1432	  If the address range available to the kernel is less than the
1433	  physical memory installed, the remaining memory will be available
1434	  as "high memory". Accessing high memory is a little more costly
1435	  than low memory, as it needs to be mapped into the kernel first.
1436	  Note that increasing the kernel address space limits the range
1437	  available to user programs, making the address space there
1438	  tighter.  Selecting anything other than the default 3G/1G split
1439	  will also likely make your kernel incompatible with binary-only
1440	  kernel modules.
1441
1442	  If you are not absolutely sure what you are doing, leave this
1443	  option alone!
1444
1445	config VMSPLIT_3G
1446		bool "3G/1G user/kernel split"
1447	config VMSPLIT_3G_OPT
1448		depends on !X86_PAE
1449		bool "3G/1G user/kernel split (for full 1G low memory)"
1450	config VMSPLIT_2G
1451		bool "2G/2G user/kernel split"
1452	config VMSPLIT_2G_OPT
1453		depends on !X86_PAE
1454		bool "2G/2G user/kernel split (for full 2G low memory)"
1455	config VMSPLIT_1G
1456		bool "1G/3G user/kernel split"
1457endchoice
1458
1459config PAGE_OFFSET
1460	hex
1461	default 0xB0000000 if VMSPLIT_3G_OPT
1462	default 0x80000000 if VMSPLIT_2G
1463	default 0x78000000 if VMSPLIT_2G_OPT
1464	default 0x40000000 if VMSPLIT_1G
1465	default 0xC0000000
1466	depends on X86_32
1467
1468config HIGHMEM
1469	def_bool y
1470	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1471
1472config X86_PAE
1473	bool "PAE (Physical Address Extension) Support"
1474	depends on X86_32 && !HIGHMEM4G
1475	select PHYS_ADDR_T_64BIT
1476	select SWIOTLB
1477	help
1478	  PAE is required for NX support, and furthermore enables
1479	  larger swapspace support for non-overcommit purposes. It
1480	  has the cost of more pagetable lookup overhead, and also
1481	  consumes more pagetable space per process.
1482
1483config X86_5LEVEL
1484	bool "Enable 5-level page tables support"
1485	default y
1486	select DYNAMIC_MEMORY_LAYOUT
1487	select SPARSEMEM_VMEMMAP
1488	depends on X86_64
1489	help
1490	  5-level paging enables access to larger address space:
1491	  upto 128 PiB of virtual address space and 4 PiB of
1492	  physical address space.
1493
1494	  It will be supported by future Intel CPUs.
1495
1496	  A kernel with the option enabled can be booted on machines that
1497	  support 4- or 5-level paging.
1498
1499	  See Documentation/x86/x86_64/5level-paging.rst for more
1500	  information.
1501
1502	  Say N if unsure.
1503
1504config X86_DIRECT_GBPAGES
1505	def_bool y
1506	depends on X86_64
1507	help
1508	  Certain kernel features effectively disable kernel
1509	  linear 1 GB mappings (even if the CPU otherwise
1510	  supports them), so don't confuse the user by printing
1511	  that we have them enabled.
1512
1513config X86_CPA_STATISTICS
1514	bool "Enable statistic for Change Page Attribute"
1515	depends on DEBUG_FS
1516	help
1517	  Expose statistics about the Change Page Attribute mechanism, which
1518	  helps to determine the effectiveness of preserving large and huge
1519	  page mappings when mapping protections are changed.
1520
1521config X86_MEM_ENCRYPT
1522	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1523	select DYNAMIC_PHYSICAL_MASK
1524	select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1525	def_bool n
1526
1527config AMD_MEM_ENCRYPT
1528	bool "AMD Secure Memory Encryption (SME) support"
1529	depends on X86_64 && CPU_SUP_AMD
1530	select DMA_COHERENT_POOL
1531	select ARCH_USE_MEMREMAP_PROT
1532	select INSTRUCTION_DECODER
1533	select ARCH_HAS_CC_PLATFORM
1534	select X86_MEM_ENCRYPT
1535	help
1536	  Say yes to enable support for the encryption of system memory.
1537	  This requires an AMD processor that supports Secure Memory
1538	  Encryption (SME).
1539
1540config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1541	bool "Activate AMD Secure Memory Encryption (SME) by default"
1542	depends on AMD_MEM_ENCRYPT
1543	help
1544	  Say yes to have system memory encrypted by default if running on
1545	  an AMD processor that supports Secure Memory Encryption (SME).
1546
1547	  If set to Y, then the encryption of system memory can be
1548	  deactivated with the mem_encrypt=off command line option.
1549
1550	  If set to N, then the encryption of system memory can be
1551	  activated with the mem_encrypt=on command line option.
1552
1553# Common NUMA Features
1554config NUMA
1555	bool "NUMA Memory Allocation and Scheduler Support"
1556	depends on SMP
1557	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1558	default y if X86_BIGSMP
1559	select USE_PERCPU_NUMA_NODE_ID
1560	help
1561	  Enable NUMA (Non-Uniform Memory Access) support.
1562
1563	  The kernel will try to allocate memory used by a CPU on the
1564	  local memory controller of the CPU and add some more
1565	  NUMA awareness to the kernel.
1566
1567	  For 64-bit this is recommended if the system is Intel Core i7
1568	  (or later), AMD Opteron, or EM64T NUMA.
1569
1570	  For 32-bit this is only needed if you boot a 32-bit
1571	  kernel on a 64-bit NUMA platform.
1572
1573	  Otherwise, you should say N.
1574
1575config AMD_NUMA
1576	def_bool y
1577	prompt "Old style AMD Opteron NUMA detection"
1578	depends on X86_64 && NUMA && PCI
1579	help
1580	  Enable AMD NUMA node topology detection.  You should say Y here if
1581	  you have a multi processor AMD system. This uses an old method to
1582	  read the NUMA configuration directly from the builtin Northbridge
1583	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1584	  which also takes priority if both are compiled in.
1585
1586config X86_64_ACPI_NUMA
1587	def_bool y
1588	prompt "ACPI NUMA detection"
1589	depends on X86_64 && NUMA && ACPI && PCI
1590	select ACPI_NUMA
1591	help
1592	  Enable ACPI SRAT based node topology detection.
1593
1594config NUMA_EMU
1595	bool "NUMA emulation"
1596	depends on NUMA
1597	help
1598	  Enable NUMA emulation. A flat machine will be split
1599	  into virtual nodes when booted with "numa=fake=N", where N is the
1600	  number of nodes. This is only useful for debugging.
1601
1602config NODES_SHIFT
1603	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1604	range 1 10
1605	default "10" if MAXSMP
1606	default "6" if X86_64
1607	default "3"
1608	depends on NUMA
1609	help
1610	  Specify the maximum number of NUMA Nodes available on the target
1611	  system.  Increases memory reserved to accommodate various tables.
1612
1613config ARCH_FLATMEM_ENABLE
1614	def_bool y
1615	depends on X86_32 && !NUMA
1616
1617config ARCH_SPARSEMEM_ENABLE
1618	def_bool y
1619	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1620	select SPARSEMEM_STATIC if X86_32
1621	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1622
1623config ARCH_SPARSEMEM_DEFAULT
1624	def_bool X86_64 || (NUMA && X86_32)
1625
1626config ARCH_SELECT_MEMORY_MODEL
1627	def_bool y
1628	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1629
1630config ARCH_MEMORY_PROBE
1631	bool "Enable sysfs memory/probe interface"
1632	depends on MEMORY_HOTPLUG
1633	help
1634	  This option enables a sysfs memory/probe interface for testing.
1635	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1636	  If you are unsure how to answer this question, answer N.
1637
1638config ARCH_PROC_KCORE_TEXT
1639	def_bool y
1640	depends on X86_64 && PROC_KCORE
1641
1642config ILLEGAL_POINTER_VALUE
1643	hex
1644	default 0 if X86_32
1645	default 0xdead000000000000 if X86_64
1646
1647config X86_PMEM_LEGACY_DEVICE
1648	bool
1649
1650config X86_PMEM_LEGACY
1651	tristate "Support non-standard NVDIMMs and ADR protected memory"
1652	depends on PHYS_ADDR_T_64BIT
1653	depends on BLK_DEV
1654	select X86_PMEM_LEGACY_DEVICE
1655	select NUMA_KEEP_MEMINFO if NUMA
1656	select LIBNVDIMM
1657	help
1658	  Treat memory marked using the non-standard e820 type of 12 as used
1659	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1660	  The kernel will offer these regions to the 'pmem' driver so
1661	  they can be used for persistent storage.
1662
1663	  Say Y if unsure.
1664
1665config HIGHPTE
1666	bool "Allocate 3rd-level pagetables from highmem"
1667	depends on HIGHMEM
1668	help
1669	  The VM uses one page table entry for each page of physical memory.
1670	  For systems with a lot of RAM, this can be wasteful of precious
1671	  low memory.  Setting this option will put user-space page table
1672	  entries in high memory.
1673
1674config X86_CHECK_BIOS_CORRUPTION
1675	bool "Check for low memory corruption"
1676	help
1677	  Periodically check for memory corruption in low memory, which
1678	  is suspected to be caused by BIOS.  Even when enabled in the
1679	  configuration, it is disabled at runtime.  Enable it by
1680	  setting "memory_corruption_check=1" on the kernel command
1681	  line.  By default it scans the low 64k of memory every 60
1682	  seconds; see the memory_corruption_check_size and
1683	  memory_corruption_check_period parameters in
1684	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1685
1686	  When enabled with the default parameters, this option has
1687	  almost no overhead, as it reserves a relatively small amount
1688	  of memory and scans it infrequently.  It both detects corruption
1689	  and prevents it from affecting the running system.
1690
1691	  It is, however, intended as a diagnostic tool; if repeatable
1692	  BIOS-originated corruption always affects the same memory,
1693	  you can use memmap= to prevent the kernel from using that
1694	  memory.
1695
1696config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1697	bool "Set the default setting of memory_corruption_check"
1698	depends on X86_CHECK_BIOS_CORRUPTION
1699	default y
1700	help
1701	  Set whether the default state of memory_corruption_check is
1702	  on or off.
1703
1704config MATH_EMULATION
1705	bool
1706	depends on MODIFY_LDT_SYSCALL
1707	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1708	help
1709	  Linux can emulate a math coprocessor (used for floating point
1710	  operations) if you don't have one. 486DX and Pentium processors have
1711	  a math coprocessor built in, 486SX and 386 do not, unless you added
1712	  a 487DX or 387, respectively. (The messages during boot time can
1713	  give you some hints here ["man dmesg"].) Everyone needs either a
1714	  coprocessor or this emulation.
1715
1716	  If you don't have a math coprocessor, you need to say Y here; if you
1717	  say Y here even though you have a coprocessor, the coprocessor will
1718	  be used nevertheless. (This behavior can be changed with the kernel
1719	  command line option "no387", which comes handy if your coprocessor
1720	  is broken. Try "man bootparam" or see the documentation of your boot
1721	  loader (lilo or loadlin) about how to pass options to the kernel at
1722	  boot time.) This means that it is a good idea to say Y here if you
1723	  intend to use this kernel on different machines.
1724
1725	  More information about the internals of the Linux math coprocessor
1726	  emulation can be found in <file:arch/x86/math-emu/README>.
1727
1728	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1729	  kernel, it won't hurt.
1730
1731config MTRR
1732	def_bool y
1733	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1734	help
1735	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1736	  the Memory Type Range Registers (MTRRs) may be used to control
1737	  processor access to memory ranges. This is most useful if you have
1738	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1739	  allows bus write transfers to be combined into a larger transfer
1740	  before bursting over the PCI/AGP bus. This can increase performance
1741	  of image write operations 2.5 times or more. Saying Y here creates a
1742	  /proc/mtrr file which may be used to manipulate your processor's
1743	  MTRRs. Typically the X server should use this.
1744
1745	  This code has a reasonably generic interface so that similar
1746	  control registers on other processors can be easily supported
1747	  as well:
1748
1749	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1750	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1751	  these, the ARRs are used to emulate the MTRRs.
1752	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1753	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1754	  write-combining. All of these processors are supported by this code
1755	  and it makes sense to say Y here if you have one of them.
1756
1757	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1758	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1759	  can lead to all sorts of problems, so it's good to say Y here.
1760
1761	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1762	  just add about 9 KB to your kernel.
1763
1764	  See <file:Documentation/x86/mtrr.rst> for more information.
1765
1766config MTRR_SANITIZER
1767	def_bool y
1768	prompt "MTRR cleanup support"
1769	depends on MTRR
1770	help
1771	  Convert MTRR layout from continuous to discrete, so X drivers can
1772	  add writeback entries.
1773
1774	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1775	  The largest mtrr entry size for a continuous block can be set with
1776	  mtrr_chunk_size.
1777
1778	  If unsure, say Y.
1779
1780config MTRR_SANITIZER_ENABLE_DEFAULT
1781	int "MTRR cleanup enable value (0-1)"
1782	range 0 1
1783	default "0"
1784	depends on MTRR_SANITIZER
1785	help
1786	  Enable mtrr cleanup default value
1787
1788config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1789	int "MTRR cleanup spare reg num (0-7)"
1790	range 0 7
1791	default "1"
1792	depends on MTRR_SANITIZER
1793	help
1794	  mtrr cleanup spare entries default, it can be changed via
1795	  mtrr_spare_reg_nr=N on the kernel command line.
1796
1797config X86_PAT
1798	def_bool y
1799	prompt "x86 PAT support" if EXPERT
1800	depends on MTRR
1801	help
1802	  Use PAT attributes to setup page level cache control.
1803
1804	  PATs are the modern equivalents of MTRRs and are much more
1805	  flexible than MTRRs.
1806
1807	  Say N here if you see bootup problems (boot crash, boot hang,
1808	  spontaneous reboots) or a non-working video driver.
1809
1810	  If unsure, say Y.
1811
1812config ARCH_USES_PG_UNCACHED
1813	def_bool y
1814	depends on X86_PAT
1815
1816config ARCH_RANDOM
1817	def_bool y
1818	prompt "x86 architectural random number generator" if EXPERT
1819	help
1820	  Enable the x86 architectural RDRAND instruction
1821	  (Intel Bull Mountain technology) to generate random numbers.
1822	  If supported, this is a high bandwidth, cryptographically
1823	  secure hardware random number generator.
1824
1825config X86_SMAP
1826	def_bool y
1827	prompt "Supervisor Mode Access Prevention" if EXPERT
1828	help
1829	  Supervisor Mode Access Prevention (SMAP) is a security
1830	  feature in newer Intel processors.  There is a small
1831	  performance cost if this enabled and turned on; there is
1832	  also a small increase in the kernel size if this is enabled.
1833
1834	  If unsure, say Y.
1835
1836config X86_UMIP
1837	def_bool y
1838	prompt "User Mode Instruction Prevention" if EXPERT
1839	help
1840	  User Mode Instruction Prevention (UMIP) is a security feature in
1841	  some x86 processors. If enabled, a general protection fault is
1842	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1843	  executed in user mode. These instructions unnecessarily expose
1844	  information about the hardware state.
1845
1846	  The vast majority of applications do not use these instructions.
1847	  For the very few that do, software emulation is provided in
1848	  specific cases in protected and virtual-8086 modes. Emulated
1849	  results are dummy.
1850
1851config CC_HAS_IBT
1852	# GCC >= 9 and binutils >= 2.29
1853	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1854	# Clang/LLVM >= 14
1855	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1856	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1857	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1858		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1859		  $(as-instr,endbr64)
1860
1861config X86_KERNEL_IBT
1862	prompt "Indirect Branch Tracking"
1863	bool
1864	depends on X86_64 && CC_HAS_IBT && STACK_VALIDATION
1865	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1866	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1867	help
1868	  Build the kernel with support for Indirect Branch Tracking, a
1869	  hardware support course-grain forward-edge Control Flow Integrity
1870	  protection. It enforces that all indirect calls must land on
1871	  an ENDBR instruction, as such, the compiler will instrument the
1872	  code with them to make this happen.
1873
1874	  In addition to building the kernel with IBT, seal all functions that
1875	  are not indirect call targets, avoiding them ever becoming one.
1876
1877	  This requires LTO like objtool runs and will slow down the build. It
1878	  does significantly reduce the number of ENDBR instructions in the
1879	  kernel image.
1880
1881config X86_INTEL_MEMORY_PROTECTION_KEYS
1882	prompt "Memory Protection Keys"
1883	def_bool y
1884	# Note: only available in 64-bit mode
1885	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1886	select ARCH_USES_HIGH_VMA_FLAGS
1887	select ARCH_HAS_PKEYS
1888	help
1889	  Memory Protection Keys provides a mechanism for enforcing
1890	  page-based protections, but without requiring modification of the
1891	  page tables when an application changes protection domains.
1892
1893	  For details, see Documentation/core-api/protection-keys.rst
1894
1895	  If unsure, say y.
1896
1897choice
1898	prompt "TSX enable mode"
1899	depends on CPU_SUP_INTEL
1900	default X86_INTEL_TSX_MODE_OFF
1901	help
1902	  Intel's TSX (Transactional Synchronization Extensions) feature
1903	  allows to optimize locking protocols through lock elision which
1904	  can lead to a noticeable performance boost.
1905
1906	  On the other hand it has been shown that TSX can be exploited
1907	  to form side channel attacks (e.g. TAA) and chances are there
1908	  will be more of those attacks discovered in the future.
1909
1910	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1911	  might override this decision by tsx=on the command line parameter.
1912	  Even with TSX enabled, the kernel will attempt to enable the best
1913	  possible TAA mitigation setting depending on the microcode available
1914	  for the particular machine.
1915
1916	  This option allows to set the default tsx mode between tsx=on, =off
1917	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1918	  details.
1919
1920	  Say off if not sure, auto if TSX is in use but it should be used on safe
1921	  platforms or on if TSX is in use and the security aspect of tsx is not
1922	  relevant.
1923
1924config X86_INTEL_TSX_MODE_OFF
1925	bool "off"
1926	help
1927	  TSX is disabled if possible - equals to tsx=off command line parameter.
1928
1929config X86_INTEL_TSX_MODE_ON
1930	bool "on"
1931	help
1932	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1933	  line parameter.
1934
1935config X86_INTEL_TSX_MODE_AUTO
1936	bool "auto"
1937	help
1938	  TSX is enabled on TSX capable HW that is believed to be safe against
1939	  side channel attacks- equals the tsx=auto command line parameter.
1940endchoice
1941
1942config X86_SGX
1943	bool "Software Guard eXtensions (SGX)"
1944	depends on X86_64 && CPU_SUP_INTEL
1945	depends on CRYPTO=y
1946	depends on CRYPTO_SHA256=y
1947	select SRCU
1948	select MMU_NOTIFIER
1949	select NUMA_KEEP_MEMINFO if NUMA
1950	select XARRAY_MULTI
1951	help
1952	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1953	  that can be used by applications to set aside private regions of code
1954	  and data, referred to as enclaves. An enclave's private memory can
1955	  only be accessed by code running within the enclave. Accesses from
1956	  outside the enclave, including other enclaves, are disallowed by
1957	  hardware.
1958
1959	  If unsure, say N.
1960
1961config EFI
1962	bool "EFI runtime service support"
1963	depends on ACPI
1964	select UCS2_STRING
1965	select EFI_RUNTIME_WRAPPERS
1966	select ARCH_USE_MEMREMAP_PROT
1967	help
1968	  This enables the kernel to use EFI runtime services that are
1969	  available (such as the EFI variable services).
1970
1971	  This option is only useful on systems that have EFI firmware.
1972	  In addition, you should use the latest ELILO loader available
1973	  at <http://elilo.sourceforge.net> in order to take advantage
1974	  of EFI runtime services. However, even with this option, the
1975	  resultant kernel should continue to boot on existing non-EFI
1976	  platforms.
1977
1978config EFI_STUB
1979	bool "EFI stub support"
1980	depends on EFI
1981	depends on $(cc-option,-mabi=ms) || X86_32
1982	select RELOCATABLE
1983	help
1984	  This kernel feature allows a bzImage to be loaded directly
1985	  by EFI firmware without the use of a bootloader.
1986
1987	  See Documentation/admin-guide/efi-stub.rst for more information.
1988
1989config EFI_MIXED
1990	bool "EFI mixed-mode support"
1991	depends on EFI_STUB && X86_64
1992	help
1993	   Enabling this feature allows a 64-bit kernel to be booted
1994	   on a 32-bit firmware, provided that your CPU supports 64-bit
1995	   mode.
1996
1997	   Note that it is not possible to boot a mixed-mode enabled
1998	   kernel via the EFI boot stub - a bootloader that supports
1999	   the EFI handover protocol must be used.
2000
2001	   If unsure, say N.
2002
2003source "kernel/Kconfig.hz"
2004
2005config KEXEC
2006	bool "kexec system call"
2007	select KEXEC_CORE
2008	help
2009	  kexec is a system call that implements the ability to shutdown your
2010	  current kernel, and to start another kernel.  It is like a reboot
2011	  but it is independent of the system firmware.   And like a reboot
2012	  you can start any kernel with it, not just Linux.
2013
2014	  The name comes from the similarity to the exec system call.
2015
2016	  It is an ongoing process to be certain the hardware in a machine
2017	  is properly shutdown, so do not be surprised if this code does not
2018	  initially work for you.  As of this writing the exact hardware
2019	  interface is strongly in flux, so no good recommendation can be
2020	  made.
2021
2022config KEXEC_FILE
2023	bool "kexec file based system call"
2024	select KEXEC_CORE
2025	select BUILD_BIN2C
2026	depends on X86_64
2027	depends on CRYPTO=y
2028	depends on CRYPTO_SHA256=y
2029	help
2030	  This is new version of kexec system call. This system call is
2031	  file based and takes file descriptors as system call argument
2032	  for kernel and initramfs as opposed to list of segments as
2033	  accepted by previous system call.
2034
2035config ARCH_HAS_KEXEC_PURGATORY
2036	def_bool KEXEC_FILE
2037
2038config KEXEC_SIG
2039	bool "Verify kernel signature during kexec_file_load() syscall"
2040	depends on KEXEC_FILE
2041	help
2042
2043	  This option makes the kexec_file_load() syscall check for a valid
2044	  signature of the kernel image.  The image can still be loaded without
2045	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2046	  there's a signature that we can check, then it must be valid.
2047
2048	  In addition to this option, you need to enable signature
2049	  verification for the corresponding kernel image type being
2050	  loaded in order for this to work.
2051
2052config KEXEC_SIG_FORCE
2053	bool "Require a valid signature in kexec_file_load() syscall"
2054	depends on KEXEC_SIG
2055	help
2056	  This option makes kernel signature verification mandatory for
2057	  the kexec_file_load() syscall.
2058
2059config KEXEC_BZIMAGE_VERIFY_SIG
2060	bool "Enable bzImage signature verification support"
2061	depends on KEXEC_SIG
2062	depends on SIGNED_PE_FILE_VERIFICATION
2063	select SYSTEM_TRUSTED_KEYRING
2064	help
2065	  Enable bzImage signature verification support.
2066
2067config CRASH_DUMP
2068	bool "kernel crash dumps"
2069	depends on X86_64 || (X86_32 && HIGHMEM)
2070	help
2071	  Generate crash dump after being started by kexec.
2072	  This should be normally only set in special crash dump kernels
2073	  which are loaded in the main kernel with kexec-tools into
2074	  a specially reserved region and then later executed after
2075	  a crash by kdump/kexec. The crash dump kernel must be compiled
2076	  to a memory address not used by the main kernel or BIOS using
2077	  PHYSICAL_START, or it must be built as a relocatable image
2078	  (CONFIG_RELOCATABLE=y).
2079	  For more details see Documentation/admin-guide/kdump/kdump.rst
2080
2081config KEXEC_JUMP
2082	bool "kexec jump"
2083	depends on KEXEC && HIBERNATION
2084	help
2085	  Jump between original kernel and kexeced kernel and invoke
2086	  code in physical address mode via KEXEC
2087
2088config PHYSICAL_START
2089	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2090	default "0x1000000"
2091	help
2092	  This gives the physical address where the kernel is loaded.
2093
2094	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2095	  bzImage will decompress itself to above physical address and
2096	  run from there. Otherwise, bzImage will run from the address where
2097	  it has been loaded by the boot loader and will ignore above physical
2098	  address.
2099
2100	  In normal kdump cases one does not have to set/change this option
2101	  as now bzImage can be compiled as a completely relocatable image
2102	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2103	  address. This option is mainly useful for the folks who don't want
2104	  to use a bzImage for capturing the crash dump and want to use a
2105	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2106	  to be specifically compiled to run from a specific memory area
2107	  (normally a reserved region) and this option comes handy.
2108
2109	  So if you are using bzImage for capturing the crash dump,
2110	  leave the value here unchanged to 0x1000000 and set
2111	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2112	  for capturing the crash dump change this value to start of
2113	  the reserved region.  In other words, it can be set based on
2114	  the "X" value as specified in the "crashkernel=YM@XM"
2115	  command line boot parameter passed to the panic-ed
2116	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2117	  for more details about crash dumps.
2118
2119	  Usage of bzImage for capturing the crash dump is recommended as
2120	  one does not have to build two kernels. Same kernel can be used
2121	  as production kernel and capture kernel. Above option should have
2122	  gone away after relocatable bzImage support is introduced. But it
2123	  is present because there are users out there who continue to use
2124	  vmlinux for dump capture. This option should go away down the
2125	  line.
2126
2127	  Don't change this unless you know what you are doing.
2128
2129config RELOCATABLE
2130	bool "Build a relocatable kernel"
2131	default y
2132	help
2133	  This builds a kernel image that retains relocation information
2134	  so it can be loaded someplace besides the default 1MB.
2135	  The relocations tend to make the kernel binary about 10% larger,
2136	  but are discarded at runtime.
2137
2138	  One use is for the kexec on panic case where the recovery kernel
2139	  must live at a different physical address than the primary
2140	  kernel.
2141
2142	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2143	  it has been loaded at and the compile time physical address
2144	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2145
2146config RANDOMIZE_BASE
2147	bool "Randomize the address of the kernel image (KASLR)"
2148	depends on RELOCATABLE
2149	default y
2150	help
2151	  In support of Kernel Address Space Layout Randomization (KASLR),
2152	  this randomizes the physical address at which the kernel image
2153	  is decompressed and the virtual address where the kernel
2154	  image is mapped, as a security feature that deters exploit
2155	  attempts relying on knowledge of the location of kernel
2156	  code internals.
2157
2158	  On 64-bit, the kernel physical and virtual addresses are
2159	  randomized separately. The physical address will be anywhere
2160	  between 16MB and the top of physical memory (up to 64TB). The
2161	  virtual address will be randomized from 16MB up to 1GB (9 bits
2162	  of entropy). Note that this also reduces the memory space
2163	  available to kernel modules from 1.5GB to 1GB.
2164
2165	  On 32-bit, the kernel physical and virtual addresses are
2166	  randomized together. They will be randomized from 16MB up to
2167	  512MB (8 bits of entropy).
2168
2169	  Entropy is generated using the RDRAND instruction if it is
2170	  supported. If RDTSC is supported, its value is mixed into
2171	  the entropy pool as well. If neither RDRAND nor RDTSC are
2172	  supported, then entropy is read from the i8254 timer. The
2173	  usable entropy is limited by the kernel being built using
2174	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2175	  minimum of 2MB. As a result, only 10 bits of entropy are
2176	  theoretically possible, but the implementations are further
2177	  limited due to memory layouts.
2178
2179	  If unsure, say Y.
2180
2181# Relocation on x86 needs some additional build support
2182config X86_NEED_RELOCS
2183	def_bool y
2184	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2185
2186config PHYSICAL_ALIGN
2187	hex "Alignment value to which kernel should be aligned"
2188	default "0x200000"
2189	range 0x2000 0x1000000 if X86_32
2190	range 0x200000 0x1000000 if X86_64
2191	help
2192	  This value puts the alignment restrictions on physical address
2193	  where kernel is loaded and run from. Kernel is compiled for an
2194	  address which meets above alignment restriction.
2195
2196	  If bootloader loads the kernel at a non-aligned address and
2197	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2198	  address aligned to above value and run from there.
2199
2200	  If bootloader loads the kernel at a non-aligned address and
2201	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2202	  load address and decompress itself to the address it has been
2203	  compiled for and run from there. The address for which kernel is
2204	  compiled already meets above alignment restrictions. Hence the
2205	  end result is that kernel runs from a physical address meeting
2206	  above alignment restrictions.
2207
2208	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2209	  this value must be a multiple of 0x200000.
2210
2211	  Don't change this unless you know what you are doing.
2212
2213config DYNAMIC_MEMORY_LAYOUT
2214	bool
2215	help
2216	  This option makes base addresses of vmalloc and vmemmap as well as
2217	  __PAGE_OFFSET movable during boot.
2218
2219config RANDOMIZE_MEMORY
2220	bool "Randomize the kernel memory sections"
2221	depends on X86_64
2222	depends on RANDOMIZE_BASE
2223	select DYNAMIC_MEMORY_LAYOUT
2224	default RANDOMIZE_BASE
2225	help
2226	   Randomizes the base virtual address of kernel memory sections
2227	   (physical memory mapping, vmalloc & vmemmap). This security feature
2228	   makes exploits relying on predictable memory locations less reliable.
2229
2230	   The order of allocations remains unchanged. Entropy is generated in
2231	   the same way as RANDOMIZE_BASE. Current implementation in the optimal
2232	   configuration have in average 30,000 different possible virtual
2233	   addresses for each memory section.
2234
2235	   If unsure, say Y.
2236
2237config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2238	hex "Physical memory mapping padding" if EXPERT
2239	depends on RANDOMIZE_MEMORY
2240	default "0xa" if MEMORY_HOTPLUG
2241	default "0x0"
2242	range 0x1 0x40 if MEMORY_HOTPLUG
2243	range 0x0 0x40
2244	help
2245	   Define the padding in terabytes added to the existing physical
2246	   memory size during kernel memory randomization. It is useful
2247	   for memory hotplug support but reduces the entropy available for
2248	   address randomization.
2249
2250	   If unsure, leave at the default value.
2251
2252config HOTPLUG_CPU
2253	def_bool y
2254	depends on SMP
2255
2256config BOOTPARAM_HOTPLUG_CPU0
2257	bool "Set default setting of cpu0_hotpluggable"
2258	depends on HOTPLUG_CPU
2259	help
2260	  Set whether default state of cpu0_hotpluggable is on or off.
2261
2262	  Say Y here to enable CPU0 hotplug by default. If this switch
2263	  is turned on, there is no need to give cpu0_hotplug kernel
2264	  parameter and the CPU0 hotplug feature is enabled by default.
2265
2266	  Please note: there are two known CPU0 dependencies if you want
2267	  to enable the CPU0 hotplug feature either by this switch or by
2268	  cpu0_hotplug kernel parameter.
2269
2270	  First, resume from hibernate or suspend always starts from CPU0.
2271	  So hibernate and suspend are prevented if CPU0 is offline.
2272
2273	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2274	  offline if any interrupt can not migrate out of CPU0. There may
2275	  be other CPU0 dependencies.
2276
2277	  Please make sure the dependencies are under your control before
2278	  you enable this feature.
2279
2280	  Say N if you don't want to enable CPU0 hotplug feature by default.
2281	  You still can enable the CPU0 hotplug feature at boot by kernel
2282	  parameter cpu0_hotplug.
2283
2284config DEBUG_HOTPLUG_CPU0
2285	def_bool n
2286	prompt "Debug CPU0 hotplug"
2287	depends on HOTPLUG_CPU
2288	help
2289	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2290	  soon as possible and boots up userspace with CPU0 offlined. User
2291	  can online CPU0 back after boot time.
2292
2293	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2294	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2295	  compilation or giving cpu0_hotplug kernel parameter at boot.
2296
2297	  If unsure, say N.
2298
2299config COMPAT_VDSO
2300	def_bool n
2301	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2302	depends on COMPAT_32
2303	help
2304	  Certain buggy versions of glibc will crash if they are
2305	  presented with a 32-bit vDSO that is not mapped at the address
2306	  indicated in its segment table.
2307
2308	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2309	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2310	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2311	  the only released version with the bug, but OpenSUSE 9
2312	  contains a buggy "glibc 2.3.2".
2313
2314	  The symptom of the bug is that everything crashes on startup, saying:
2315	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2316
2317	  Saying Y here changes the default value of the vdso32 boot
2318	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2319	  This works around the glibc bug but hurts performance.
2320
2321	  If unsure, say N: if you are compiling your own kernel, you
2322	  are unlikely to be using a buggy version of glibc.
2323
2324choice
2325	prompt "vsyscall table for legacy applications"
2326	depends on X86_64
2327	default LEGACY_VSYSCALL_XONLY
2328	help
2329	  Legacy user code that does not know how to find the vDSO expects
2330	  to be able to issue three syscalls by calling fixed addresses in
2331	  kernel space. Since this location is not randomized with ASLR,
2332	  it can be used to assist security vulnerability exploitation.
2333
2334	  This setting can be changed at boot time via the kernel command
2335	  line parameter vsyscall=[emulate|xonly|none].
2336
2337	  On a system with recent enough glibc (2.14 or newer) and no
2338	  static binaries, you can say None without a performance penalty
2339	  to improve security.
2340
2341	  If unsure, select "Emulate execution only".
2342
2343	config LEGACY_VSYSCALL_EMULATE
2344		bool "Full emulation"
2345		help
2346		  The kernel traps and emulates calls into the fixed vsyscall
2347		  address mapping. This makes the mapping non-executable, but
2348		  it still contains readable known contents, which could be
2349		  used in certain rare security vulnerability exploits. This
2350		  configuration is recommended when using legacy userspace
2351		  that still uses vsyscalls along with legacy binary
2352		  instrumentation tools that require code to be readable.
2353
2354		  An example of this type of legacy userspace is running
2355		  Pin on an old binary that still uses vsyscalls.
2356
2357	config LEGACY_VSYSCALL_XONLY
2358		bool "Emulate execution only"
2359		help
2360		  The kernel traps and emulates calls into the fixed vsyscall
2361		  address mapping and does not allow reads.  This
2362		  configuration is recommended when userspace might use the
2363		  legacy vsyscall area but support for legacy binary
2364		  instrumentation of legacy code is not needed.  It mitigates
2365		  certain uses of the vsyscall area as an ASLR-bypassing
2366		  buffer.
2367
2368	config LEGACY_VSYSCALL_NONE
2369		bool "None"
2370		help
2371		  There will be no vsyscall mapping at all. This will
2372		  eliminate any risk of ASLR bypass due to the vsyscall
2373		  fixed address mapping. Attempts to use the vsyscalls
2374		  will be reported to dmesg, so that either old or
2375		  malicious userspace programs can be identified.
2376
2377endchoice
2378
2379config CMDLINE_BOOL
2380	bool "Built-in kernel command line"
2381	help
2382	  Allow for specifying boot arguments to the kernel at
2383	  build time.  On some systems (e.g. embedded ones), it is
2384	  necessary or convenient to provide some or all of the
2385	  kernel boot arguments with the kernel itself (that is,
2386	  to not rely on the boot loader to provide them.)
2387
2388	  To compile command line arguments into the kernel,
2389	  set this option to 'Y', then fill in the
2390	  boot arguments in CONFIG_CMDLINE.
2391
2392	  Systems with fully functional boot loaders (i.e. non-embedded)
2393	  should leave this option set to 'N'.
2394
2395config CMDLINE
2396	string "Built-in kernel command string"
2397	depends on CMDLINE_BOOL
2398	default ""
2399	help
2400	  Enter arguments here that should be compiled into the kernel
2401	  image and used at boot time.  If the boot loader provides a
2402	  command line at boot time, it is appended to this string to
2403	  form the full kernel command line, when the system boots.
2404
2405	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2406	  change this behavior.
2407
2408	  In most cases, the command line (whether built-in or provided
2409	  by the boot loader) should specify the device for the root
2410	  file system.
2411
2412config CMDLINE_OVERRIDE
2413	bool "Built-in command line overrides boot loader arguments"
2414	depends on CMDLINE_BOOL && CMDLINE != ""
2415	help
2416	  Set this option to 'Y' to have the kernel ignore the boot loader
2417	  command line, and use ONLY the built-in command line.
2418
2419	  This is used to work around broken boot loaders.  This should
2420	  be set to 'N' under normal conditions.
2421
2422config MODIFY_LDT_SYSCALL
2423	bool "Enable the LDT (local descriptor table)" if EXPERT
2424	default y
2425	help
2426	  Linux can allow user programs to install a per-process x86
2427	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2428	  call.  This is required to run 16-bit or segmented code such as
2429	  DOSEMU or some Wine programs.  It is also used by some very old
2430	  threading libraries.
2431
2432	  Enabling this feature adds a small amount of overhead to
2433	  context switches and increases the low-level kernel attack
2434	  surface.  Disabling it removes the modify_ldt(2) system call.
2435
2436	  Saying 'N' here may make sense for embedded or server kernels.
2437
2438config STRICT_SIGALTSTACK_SIZE
2439	bool "Enforce strict size checking for sigaltstack"
2440	depends on DYNAMIC_SIGFRAME
2441	help
2442	  For historical reasons MINSIGSTKSZ is a constant which became
2443	  already too small with AVX512 support. Add a mechanism to
2444	  enforce strict checking of the sigaltstack size against the
2445	  real size of the FPU frame. This option enables the check
2446	  by default. It can also be controlled via the kernel command
2447	  line option 'strict_sas_size' independent of this config
2448	  switch. Enabling it might break existing applications which
2449	  allocate a too small sigaltstack but 'work' because they
2450	  never get a signal delivered.
2451
2452	  Say 'N' unless you want to really enforce this check.
2453
2454source "kernel/livepatch/Kconfig"
2455
2456endmenu
2457
2458config ARCH_HAS_ADD_PAGES
2459	def_bool y
2460	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2461
2462config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2463	def_bool y
2464
2465menu "Power management and ACPI options"
2466
2467config ARCH_HIBERNATION_HEADER
2468	def_bool y
2469	depends on HIBERNATION
2470
2471source "kernel/power/Kconfig"
2472
2473source "drivers/acpi/Kconfig"
2474
2475config X86_APM_BOOT
2476	def_bool y
2477	depends on APM
2478
2479menuconfig APM
2480	tristate "APM (Advanced Power Management) BIOS support"
2481	depends on X86_32 && PM_SLEEP
2482	help
2483	  APM is a BIOS specification for saving power using several different
2484	  techniques. This is mostly useful for battery powered laptops with
2485	  APM compliant BIOSes. If you say Y here, the system time will be
2486	  reset after a RESUME operation, the /proc/apm device will provide
2487	  battery status information, and user-space programs will receive
2488	  notification of APM "events" (e.g. battery status change).
2489
2490	  If you select "Y" here, you can disable actual use of the APM
2491	  BIOS by passing the "apm=off" option to the kernel at boot time.
2492
2493	  Note that the APM support is almost completely disabled for
2494	  machines with more than one CPU.
2495
2496	  In order to use APM, you will need supporting software. For location
2497	  and more information, read <file:Documentation/power/apm-acpi.rst>
2498	  and the Battery Powered Linux mini-HOWTO, available from
2499	  <http://www.tldp.org/docs.html#howto>.
2500
2501	  This driver does not spin down disk drives (see the hdparm(8)
2502	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2503	  VESA-compliant "green" monitors.
2504
2505	  This driver does not support the TI 4000M TravelMate and the ACER
2506	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2507	  desktop machines also don't have compliant BIOSes, and this driver
2508	  may cause those machines to panic during the boot phase.
2509
2510	  Generally, if you don't have a battery in your machine, there isn't
2511	  much point in using this driver and you should say N. If you get
2512	  random kernel OOPSes or reboots that don't seem to be related to
2513	  anything, try disabling/enabling this option (or disabling/enabling
2514	  APM in your BIOS).
2515
2516	  Some other things you should try when experiencing seemingly random,
2517	  "weird" problems:
2518
2519	  1) make sure that you have enough swap space and that it is
2520	  enabled.
2521	  2) pass the "no-hlt" option to the kernel
2522	  3) switch on floating point emulation in the kernel and pass
2523	  the "no387" option to the kernel
2524	  4) pass the "floppy=nodma" option to the kernel
2525	  5) pass the "mem=4M" option to the kernel (thereby disabling
2526	  all but the first 4 MB of RAM)
2527	  6) make sure that the CPU is not over clocked.
2528	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2529	  8) disable the cache from your BIOS settings
2530	  9) install a fan for the video card or exchange video RAM
2531	  10) install a better fan for the CPU
2532	  11) exchange RAM chips
2533	  12) exchange the motherboard.
2534
2535	  To compile this driver as a module, choose M here: the
2536	  module will be called apm.
2537
2538if APM
2539
2540config APM_IGNORE_USER_SUSPEND
2541	bool "Ignore USER SUSPEND"
2542	help
2543	  This option will ignore USER SUSPEND requests. On machines with a
2544	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2545	  series notebooks, it is necessary to say Y because of a BIOS bug.
2546
2547config APM_DO_ENABLE
2548	bool "Enable PM at boot time"
2549	help
2550	  Enable APM features at boot time. From page 36 of the APM BIOS
2551	  specification: "When disabled, the APM BIOS does not automatically
2552	  power manage devices, enter the Standby State, enter the Suspend
2553	  State, or take power saving steps in response to CPU Idle calls."
2554	  This driver will make CPU Idle calls when Linux is idle (unless this
2555	  feature is turned off -- see "Do CPU IDLE calls", below). This
2556	  should always save battery power, but more complicated APM features
2557	  will be dependent on your BIOS implementation. You may need to turn
2558	  this option off if your computer hangs at boot time when using APM
2559	  support, or if it beeps continuously instead of suspending. Turn
2560	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2561	  T400CDT. This is off by default since most machines do fine without
2562	  this feature.
2563
2564config APM_CPU_IDLE
2565	depends on CPU_IDLE
2566	bool "Make CPU Idle calls when idle"
2567	help
2568	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2569	  On some machines, this can activate improved power savings, such as
2570	  a slowed CPU clock rate, when the machine is idle. These idle calls
2571	  are made after the idle loop has run for some length of time (e.g.,
2572	  333 mS). On some machines, this will cause a hang at boot time or
2573	  whenever the CPU becomes idle. (On machines with more than one CPU,
2574	  this option does nothing.)
2575
2576config APM_DISPLAY_BLANK
2577	bool "Enable console blanking using APM"
2578	help
2579	  Enable console blanking using the APM. Some laptops can use this to
2580	  turn off the LCD backlight when the screen blanker of the Linux
2581	  virtual console blanks the screen. Note that this is only used by
2582	  the virtual console screen blanker, and won't turn off the backlight
2583	  when using the X Window system. This also doesn't have anything to
2584	  do with your VESA-compliant power-saving monitor. Further, this
2585	  option doesn't work for all laptops -- it might not turn off your
2586	  backlight at all, or it might print a lot of errors to the console,
2587	  especially if you are using gpm.
2588
2589config APM_ALLOW_INTS
2590	bool "Allow interrupts during APM BIOS calls"
2591	help
2592	  Normally we disable external interrupts while we are making calls to
2593	  the APM BIOS as a measure to lessen the effects of a badly behaving
2594	  BIOS implementation.  The BIOS should reenable interrupts if it
2595	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2596	  many of the newer IBM Thinkpads.  If you experience hangs when you
2597	  suspend, try setting this to Y.  Otherwise, say N.
2598
2599endif # APM
2600
2601source "drivers/cpufreq/Kconfig"
2602
2603source "drivers/cpuidle/Kconfig"
2604
2605source "drivers/idle/Kconfig"
2606
2607endmenu
2608
2609
2610menu "Bus options (PCI etc.)"
2611
2612choice
2613	prompt "PCI access mode"
2614	depends on X86_32 && PCI
2615	default PCI_GOANY
2616	help
2617	  On PCI systems, the BIOS can be used to detect the PCI devices and
2618	  determine their configuration. However, some old PCI motherboards
2619	  have BIOS bugs and may crash if this is done. Also, some embedded
2620	  PCI-based systems don't have any BIOS at all. Linux can also try to
2621	  detect the PCI hardware directly without using the BIOS.
2622
2623	  With this option, you can specify how Linux should detect the
2624	  PCI devices. If you choose "BIOS", the BIOS will be used,
2625	  if you choose "Direct", the BIOS won't be used, and if you
2626	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2627	  If you choose "Any", the kernel will try MMCONFIG, then the
2628	  direct access method and falls back to the BIOS if that doesn't
2629	  work. If unsure, go with the default, which is "Any".
2630
2631config PCI_GOBIOS
2632	bool "BIOS"
2633
2634config PCI_GOMMCONFIG
2635	bool "MMConfig"
2636
2637config PCI_GODIRECT
2638	bool "Direct"
2639
2640config PCI_GOOLPC
2641	bool "OLPC XO-1"
2642	depends on OLPC
2643
2644config PCI_GOANY
2645	bool "Any"
2646
2647endchoice
2648
2649config PCI_BIOS
2650	def_bool y
2651	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2652
2653# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2654config PCI_DIRECT
2655	def_bool y
2656	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2657
2658config PCI_MMCONFIG
2659	bool "Support mmconfig PCI config space access" if X86_64
2660	default y
2661	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2662	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2663
2664config PCI_OLPC
2665	def_bool y
2666	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2667
2668config PCI_XEN
2669	def_bool y
2670	depends on PCI && XEN
2671
2672config MMCONF_FAM10H
2673	def_bool y
2674	depends on X86_64 && PCI_MMCONFIG && ACPI
2675
2676config PCI_CNB20LE_QUIRK
2677	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2678	depends on PCI
2679	help
2680	  Read the PCI windows out of the CNB20LE host bridge. This allows
2681	  PCI hotplug to work on systems with the CNB20LE chipset which do
2682	  not have ACPI.
2683
2684	  There's no public spec for this chipset, and this functionality
2685	  is known to be incomplete.
2686
2687	  You should say N unless you know you need this.
2688
2689config ISA_BUS
2690	bool "ISA bus support on modern systems" if EXPERT
2691	help
2692	  Expose ISA bus device drivers and options available for selection and
2693	  configuration. Enable this option if your target machine has an ISA
2694	  bus. ISA is an older system, displaced by PCI and newer bus
2695	  architectures -- if your target machine is modern, it probably does
2696	  not have an ISA bus.
2697
2698	  If unsure, say N.
2699
2700# x86_64 have no ISA slots, but can have ISA-style DMA.
2701config ISA_DMA_API
2702	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2703	default y
2704	help
2705	  Enables ISA-style DMA support for devices requiring such controllers.
2706	  If unsure, say Y.
2707
2708if X86_32
2709
2710config ISA
2711	bool "ISA support"
2712	help
2713	  Find out whether you have ISA slots on your motherboard.  ISA is the
2714	  name of a bus system, i.e. the way the CPU talks to the other stuff
2715	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2716	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2717	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2718
2719config SCx200
2720	tristate "NatSemi SCx200 support"
2721	help
2722	  This provides basic support for National Semiconductor's
2723	  (now AMD's) Geode processors.  The driver probes for the
2724	  PCI-IDs of several on-chip devices, so its a good dependency
2725	  for other scx200_* drivers.
2726
2727	  If compiled as a module, the driver is named scx200.
2728
2729config SCx200HR_TIMER
2730	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2731	depends on SCx200
2732	default y
2733	help
2734	  This driver provides a clocksource built upon the on-chip
2735	  27MHz high-resolution timer.  Its also a workaround for
2736	  NSC Geode SC-1100's buggy TSC, which loses time when the
2737	  processor goes idle (as is done by the scheduler).  The
2738	  other workaround is idle=poll boot option.
2739
2740config OLPC
2741	bool "One Laptop Per Child support"
2742	depends on !X86_PAE
2743	select GPIOLIB
2744	select OF
2745	select OF_PROMTREE
2746	select IRQ_DOMAIN
2747	select OLPC_EC
2748	help
2749	  Add support for detecting the unique features of the OLPC
2750	  XO hardware.
2751
2752config OLPC_XO1_PM
2753	bool "OLPC XO-1 Power Management"
2754	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2755	help
2756	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2757
2758config OLPC_XO1_RTC
2759	bool "OLPC XO-1 Real Time Clock"
2760	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2761	help
2762	  Add support for the XO-1 real time clock, which can be used as a
2763	  programmable wakeup source.
2764
2765config OLPC_XO1_SCI
2766	bool "OLPC XO-1 SCI extras"
2767	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2768	depends on INPUT=y
2769	select POWER_SUPPLY
2770	help
2771	  Add support for SCI-based features of the OLPC XO-1 laptop:
2772	   - EC-driven system wakeups
2773	   - Power button
2774	   - Ebook switch
2775	   - Lid switch
2776	   - AC adapter status updates
2777	   - Battery status updates
2778
2779config OLPC_XO15_SCI
2780	bool "OLPC XO-1.5 SCI extras"
2781	depends on OLPC && ACPI
2782	select POWER_SUPPLY
2783	help
2784	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2785	   - EC-driven system wakeups
2786	   - AC adapter status updates
2787	   - Battery status updates
2788
2789config ALIX
2790	bool "PCEngines ALIX System Support (LED setup)"
2791	select GPIOLIB
2792	help
2793	  This option enables system support for the PCEngines ALIX.
2794	  At present this just sets up LEDs for GPIO control on
2795	  ALIX2/3/6 boards.  However, other system specific setup should
2796	  get added here.
2797
2798	  Note: You must still enable the drivers for GPIO and LED support
2799	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2800
2801	  Note: You have to set alix.force=1 for boards with Award BIOS.
2802
2803config NET5501
2804	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2805	select GPIOLIB
2806	help
2807	  This option enables system support for the Soekris Engineering net5501.
2808
2809config GEOS
2810	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2811	select GPIOLIB
2812	depends on DMI
2813	help
2814	  This option enables system support for the Traverse Technologies GEOS.
2815
2816config TS5500
2817	bool "Technologic Systems TS-5500 platform support"
2818	depends on MELAN
2819	select CHECK_SIGNATURE
2820	select NEW_LEDS
2821	select LEDS_CLASS
2822	help
2823	  This option enables system support for the Technologic Systems TS-5500.
2824
2825endif # X86_32
2826
2827config AMD_NB
2828	def_bool y
2829	depends on CPU_SUP_AMD && PCI
2830
2831endmenu
2832
2833
2834menu "Binary Emulations"
2835
2836config IA32_EMULATION
2837	bool "IA32 Emulation"
2838	depends on X86_64
2839	select ARCH_WANT_OLD_COMPAT_IPC
2840	select BINFMT_ELF
2841	select COMPAT_OLD_SIGACTION
2842	help
2843	  Include code to run legacy 32-bit programs under a
2844	  64-bit kernel. You should likely turn this on, unless you're
2845	  100% sure that you don't have any 32-bit programs left.
2846
2847config IA32_AOUT
2848	tristate "IA32 a.out support"
2849	depends on IA32_EMULATION
2850	depends on BROKEN
2851	help
2852	  Support old a.out binaries in the 32bit emulation.
2853
2854config X86_X32_ABI
2855	bool "x32 ABI for 64-bit mode"
2856	depends on X86_64
2857	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2858	# compressed debug sections to x86_x32 properly:
2859	# https://github.com/ClangBuiltLinux/linux/issues/514
2860	# https://github.com/ClangBuiltLinux/linux/issues/1141
2861	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2862	help
2863	  Include code to run binaries for the x32 native 32-bit ABI
2864	  for 64-bit processors.  An x32 process gets access to the
2865	  full 64-bit register file and wide data path while leaving
2866	  pointers at 32 bits for smaller memory footprint.
2867
2868config COMPAT_32
2869	def_bool y
2870	depends on IA32_EMULATION || X86_32
2871	select HAVE_UID16
2872	select OLD_SIGSUSPEND3
2873
2874config COMPAT
2875	def_bool y
2876	depends on IA32_EMULATION || X86_X32_ABI
2877
2878if COMPAT
2879config COMPAT_FOR_U64_ALIGNMENT
2880	def_bool y
2881
2882config SYSVIPC_COMPAT
2883	def_bool y
2884	depends on SYSVIPC
2885endif
2886
2887endmenu
2888
2889
2890config HAVE_ATOMIC_IOMAP
2891	def_bool y
2892	depends on X86_32
2893
2894source "arch/x86/kvm/Kconfig"
2895
2896source "arch/x86/Kconfig.assembler"
2897