xref: /openbmc/linux/arch/x86/Kconfig (revision 65b96377)
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 MAXSMP
944	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
945	depends on X86_64 && SMP && DEBUG_KERNEL
946	select CPUMASK_OFFSTACK
947	help
948	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
949	  If unsure, say N.
950
951#
952# The maximum number of CPUs supported:
953#
954# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
955# and which can be configured interactively in the
956# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
957#
958# The ranges are different on 32-bit and 64-bit kernels, depending on
959# hardware capabilities and scalability features of the kernel.
960#
961# ( If MAXSMP is enabled we just use the highest possible value and disable
962#   interactive configuration. )
963#
964
965config NR_CPUS_RANGE_BEGIN
966	int
967	default NR_CPUS_RANGE_END if MAXSMP
968	default    1 if !SMP
969	default    2
970
971config NR_CPUS_RANGE_END
972	int
973	depends on X86_32
974	default   64 if  SMP &&  X86_BIGSMP
975	default    8 if  SMP && !X86_BIGSMP
976	default    1 if !SMP
977
978config NR_CPUS_RANGE_END
979	int
980	depends on X86_64
981	default 8192 if  SMP && CPUMASK_OFFSTACK
982	default  512 if  SMP && !CPUMASK_OFFSTACK
983	default    1 if !SMP
984
985config NR_CPUS_DEFAULT
986	int
987	depends on X86_32
988	default   32 if  X86_BIGSMP
989	default    8 if  SMP
990	default    1 if !SMP
991
992config NR_CPUS_DEFAULT
993	int
994	depends on X86_64
995	default 8192 if  MAXSMP
996	default   64 if  SMP
997	default    1 if !SMP
998
999config NR_CPUS
1000	int "Maximum number of CPUs" if SMP && !MAXSMP
1001	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1002	default NR_CPUS_DEFAULT
1003	help
1004	  This allows you to specify the maximum number of CPUs which this
1005	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1006	  supported value is 8192, otherwise the maximum value is 512.  The
1007	  minimum value which makes sense is 2.
1008
1009	  This is purely to save memory: each supported CPU adds about 8KB
1010	  to the kernel image.
1011
1012config SCHED_CLUSTER
1013	bool "Cluster scheduler support"
1014	depends on SMP
1015	default y
1016	help
1017	  Cluster scheduler support improves the CPU scheduler's decision
1018	  making when dealing with machines that have clusters of CPUs.
1019	  Cluster usually means a couple of CPUs which are placed closely
1020	  by sharing mid-level caches, last-level cache tags or internal
1021	  busses.
1022
1023config SCHED_SMT
1024	def_bool y if SMP
1025
1026config SCHED_MC
1027	def_bool y
1028	prompt "Multi-core scheduler support"
1029	depends on SMP
1030	help
1031	  Multi-core scheduler support improves the CPU scheduler's decision
1032	  making when dealing with multi-core CPU chips at a cost of slightly
1033	  increased overhead in some places. If unsure say N here.
1034
1035config SCHED_MC_PRIO
1036	bool "CPU core priorities scheduler support"
1037	depends on SCHED_MC && CPU_SUP_INTEL
1038	select X86_INTEL_PSTATE
1039	select CPU_FREQ
1040	default y
1041	help
1042	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1043	  core ordering determined at manufacturing time, which allows
1044	  certain cores to reach higher turbo frequencies (when running
1045	  single threaded workloads) than others.
1046
1047	  Enabling this kernel feature teaches the scheduler about
1048	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1049	  scheduler's CPU selection logic accordingly, so that higher
1050	  overall system performance can be achieved.
1051
1052	  This feature will have no effect on CPUs without this feature.
1053
1054	  If unsure say Y here.
1055
1056config UP_LATE_INIT
1057	def_bool y
1058	depends on !SMP && X86_LOCAL_APIC
1059
1060config X86_UP_APIC
1061	bool "Local APIC support on uniprocessors" if !PCI_MSI
1062	default PCI_MSI
1063	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1064	help
1065	  A local APIC (Advanced Programmable Interrupt Controller) is an
1066	  integrated interrupt controller in the CPU. If you have a single-CPU
1067	  system which has a processor with a local APIC, you can say Y here to
1068	  enable and use it. If you say Y here even though your machine doesn't
1069	  have a local APIC, then the kernel will still run with no slowdown at
1070	  all. The local APIC supports CPU-generated self-interrupts (timer,
1071	  performance counters), and the NMI watchdog which detects hard
1072	  lockups.
1073
1074config X86_UP_IOAPIC
1075	bool "IO-APIC support on uniprocessors"
1076	depends on X86_UP_APIC
1077	help
1078	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1079	  SMP-capable replacement for PC-style interrupt controllers. Most
1080	  SMP systems and many recent uniprocessor systems have one.
1081
1082	  If you have a single-CPU system with an IO-APIC, you can say Y here
1083	  to use it. If you say Y here even though your machine doesn't have
1084	  an IO-APIC, then the kernel will still run with no slowdown at all.
1085
1086config X86_LOCAL_APIC
1087	def_bool y
1088	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1089	select IRQ_DOMAIN_HIERARCHY
1090	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1091
1092config X86_IO_APIC
1093	def_bool y
1094	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1095
1096config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1097	bool "Reroute for broken boot IRQs"
1098	depends on X86_IO_APIC
1099	help
1100	  This option enables a workaround that fixes a source of
1101	  spurious interrupts. This is recommended when threaded
1102	  interrupt handling is used on systems where the generation of
1103	  superfluous "boot interrupts" cannot be disabled.
1104
1105	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1106	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1107	  kernel does during interrupt handling). On chipsets where this
1108	  boot IRQ generation cannot be disabled, this workaround keeps
1109	  the original IRQ line masked so that only the equivalent "boot
1110	  IRQ" is delivered to the CPUs. The workaround also tells the
1111	  kernel to set up the IRQ handler on the boot IRQ line. In this
1112	  way only one interrupt is delivered to the kernel. Otherwise
1113	  the spurious second interrupt may cause the kernel to bring
1114	  down (vital) interrupt lines.
1115
1116	  Only affects "broken" chipsets. Interrupt sharing may be
1117	  increased on these systems.
1118
1119config X86_MCE
1120	bool "Machine Check / overheating reporting"
1121	select GENERIC_ALLOCATOR
1122	default y
1123	help
1124	  Machine Check support allows the processor to notify the
1125	  kernel if it detects a problem (e.g. overheating, data corruption).
1126	  The action the kernel takes depends on the severity of the problem,
1127	  ranging from warning messages to halting the machine.
1128
1129config X86_MCELOG_LEGACY
1130	bool "Support for deprecated /dev/mcelog character device"
1131	depends on X86_MCE
1132	help
1133	  Enable support for /dev/mcelog which is needed by the old mcelog
1134	  userspace logging daemon. Consider switching to the new generation
1135	  rasdaemon solution.
1136
1137config X86_MCE_INTEL
1138	def_bool y
1139	prompt "Intel MCE features"
1140	depends on X86_MCE && X86_LOCAL_APIC
1141	help
1142	   Additional support for intel specific MCE features such as
1143	   the thermal monitor.
1144
1145config X86_MCE_AMD
1146	def_bool y
1147	prompt "AMD MCE features"
1148	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1149	help
1150	   Additional support for AMD specific MCE features such as
1151	   the DRAM Error Threshold.
1152
1153config X86_ANCIENT_MCE
1154	bool "Support for old Pentium 5 / WinChip machine checks"
1155	depends on X86_32 && X86_MCE
1156	help
1157	  Include support for machine check handling on old Pentium 5 or WinChip
1158	  systems. These typically need to be enabled explicitly on the command
1159	  line.
1160
1161config X86_MCE_THRESHOLD
1162	depends on X86_MCE_AMD || X86_MCE_INTEL
1163	def_bool y
1164
1165config X86_MCE_INJECT
1166	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1167	tristate "Machine check injector support"
1168	help
1169	  Provide support for injecting machine checks for testing purposes.
1170	  If you don't know what a machine check is and you don't do kernel
1171	  QA it is safe to say n.
1172
1173source "arch/x86/events/Kconfig"
1174
1175config X86_LEGACY_VM86
1176	bool "Legacy VM86 support"
1177	depends on X86_32
1178	help
1179	  This option allows user programs to put the CPU into V8086
1180	  mode, which is an 80286-era approximation of 16-bit real mode.
1181
1182	  Some very old versions of X and/or vbetool require this option
1183	  for user mode setting.  Similarly, DOSEMU will use it if
1184	  available to accelerate real mode DOS programs.  However, any
1185	  recent version of DOSEMU, X, or vbetool should be fully
1186	  functional even without kernel VM86 support, as they will all
1187	  fall back to software emulation. Nevertheless, if you are using
1188	  a 16-bit DOS program where 16-bit performance matters, vm86
1189	  mode might be faster than emulation and you might want to
1190	  enable this option.
1191
1192	  Note that any app that works on a 64-bit kernel is unlikely to
1193	  need this option, as 64-bit kernels don't, and can't, support
1194	  V8086 mode. This option is also unrelated to 16-bit protected
1195	  mode and is not needed to run most 16-bit programs under Wine.
1196
1197	  Enabling this option increases the complexity of the kernel
1198	  and slows down exception handling a tiny bit.
1199
1200	  If unsure, say N here.
1201
1202config VM86
1203	bool
1204	default X86_LEGACY_VM86
1205
1206config X86_16BIT
1207	bool "Enable support for 16-bit segments" if EXPERT
1208	default y
1209	depends on MODIFY_LDT_SYSCALL
1210	help
1211	  This option is required by programs like Wine to run 16-bit
1212	  protected mode legacy code on x86 processors.  Disabling
1213	  this option saves about 300 bytes on i386, or around 6K text
1214	  plus 16K runtime memory on x86-64,
1215
1216config X86_ESPFIX32
1217	def_bool y
1218	depends on X86_16BIT && X86_32
1219
1220config X86_ESPFIX64
1221	def_bool y
1222	depends on X86_16BIT && X86_64
1223
1224config X86_VSYSCALL_EMULATION
1225	bool "Enable vsyscall emulation" if EXPERT
1226	default y
1227	depends on X86_64
1228	help
1229	 This enables emulation of the legacy vsyscall page.  Disabling
1230	 it is roughly equivalent to booting with vsyscall=none, except
1231	 that it will also disable the helpful warning if a program
1232	 tries to use a vsyscall.  With this option set to N, offending
1233	 programs will just segfault, citing addresses of the form
1234	 0xffffffffff600?00.
1235
1236	 This option is required by many programs built before 2013, and
1237	 care should be used even with newer programs if set to N.
1238
1239	 Disabling this option saves about 7K of kernel size and
1240	 possibly 4K of additional runtime pagetable memory.
1241
1242config X86_IOPL_IOPERM
1243	bool "IOPERM and IOPL Emulation"
1244	default y
1245	help
1246	  This enables the ioperm() and iopl() syscalls which are necessary
1247	  for legacy applications.
1248
1249	  Legacy IOPL support is an overbroad mechanism which allows user
1250	  space aside of accessing all 65536 I/O ports also to disable
1251	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1252	  capabilities and permission from potentially active security
1253	  modules.
1254
1255	  The emulation restricts the functionality of the syscall to
1256	  only allowing the full range I/O port access, but prevents the
1257	  ability to disable interrupts from user space which would be
1258	  granted if the hardware IOPL mechanism would be used.
1259
1260config TOSHIBA
1261	tristate "Toshiba Laptop support"
1262	depends on X86_32
1263	help
1264	  This adds a driver to safely access the System Management Mode of
1265	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1266	  not work on models with a Phoenix BIOS. The System Management Mode
1267	  is used to set the BIOS and power saving options on Toshiba portables.
1268
1269	  For information on utilities to make use of this driver see the
1270	  Toshiba Linux utilities web site at:
1271	  <http://www.buzzard.org.uk/toshiba/>.
1272
1273	  Say Y if you intend to run this kernel on a Toshiba portable.
1274	  Say N otherwise.
1275
1276config X86_REBOOTFIXUPS
1277	bool "Enable X86 board specific fixups for reboot"
1278	depends on X86_32
1279	help
1280	  This enables chipset and/or board specific fixups to be done
1281	  in order to get reboot to work correctly. This is only needed on
1282	  some combinations of hardware and BIOS. The symptom, for which
1283	  this config is intended, is when reboot ends with a stalled/hung
1284	  system.
1285
1286	  Currently, the only fixup is for the Geode machines using
1287	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1288
1289	  Say Y if you want to enable the fixup. Currently, it's safe to
1290	  enable this option even if you don't need it.
1291	  Say N otherwise.
1292
1293config MICROCODE
1294	bool "CPU microcode loading support"
1295	default y
1296	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1297	help
1298	  If you say Y here, you will be able to update the microcode on
1299	  Intel and AMD processors. The Intel support is for the IA32 family,
1300	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1301	  AMD support is for families 0x10 and later. You will obviously need
1302	  the actual microcode binary data itself which is not shipped with
1303	  the Linux kernel.
1304
1305	  The preferred method to load microcode from a detached initrd is described
1306	  in Documentation/x86/microcode.rst. For that you need to enable
1307	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1308	  initrd for microcode blobs.
1309
1310	  In addition, you can build the microcode into the kernel. For that you
1311	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1312	  config option.
1313
1314config MICROCODE_INTEL
1315	bool "Intel microcode loading support"
1316	depends on MICROCODE
1317	default MICROCODE
1318	help
1319	  This options enables microcode patch loading support for Intel
1320	  processors.
1321
1322	  For the current Intel microcode data package go to
1323	  <https://downloadcenter.intel.com> and search for
1324	  'Linux Processor Microcode Data File'.
1325
1326config MICROCODE_AMD
1327	bool "AMD microcode loading support"
1328	depends on MICROCODE
1329	help
1330	  If you select this option, microcode patch loading support for AMD
1331	  processors will be enabled.
1332
1333config MICROCODE_OLD_INTERFACE
1334	bool "Ancient loading interface (DEPRECATED)"
1335	default n
1336	depends on MICROCODE
1337	help
1338	  DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1339	  which was used by userspace tools like iucode_tool and microcode.ctl.
1340	  It is inadequate because it runs too late to be able to properly
1341	  load microcode on a machine and it needs special tools. Instead, you
1342	  should've switched to the early loading method with the initrd or
1343	  builtin microcode by now: Documentation/x86/microcode.rst
1344
1345config X86_MSR
1346	tristate "/dev/cpu/*/msr - Model-specific register support"
1347	help
1348	  This device gives privileged processes access to the x86
1349	  Model-Specific Registers (MSRs).  It is a character device with
1350	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1351	  MSR accesses are directed to a specific CPU on multi-processor
1352	  systems.
1353
1354config X86_CPUID
1355	tristate "/dev/cpu/*/cpuid - CPU information support"
1356	help
1357	  This device gives processes access to the x86 CPUID instruction to
1358	  be executed on a specific processor.  It is a character device
1359	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1360	  /dev/cpu/31/cpuid.
1361
1362choice
1363	prompt "High Memory Support"
1364	default HIGHMEM4G
1365	depends on X86_32
1366
1367config NOHIGHMEM
1368	bool "off"
1369	help
1370	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1371	  However, the address space of 32-bit x86 processors is only 4
1372	  Gigabytes large. That means that, if you have a large amount of
1373	  physical memory, not all of it can be "permanently mapped" by the
1374	  kernel. The physical memory that's not permanently mapped is called
1375	  "high memory".
1376
1377	  If you are compiling a kernel which will never run on a machine with
1378	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1379	  choice and suitable for most users). This will result in a "3GB/1GB"
1380	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1381	  space and the remaining part of the 4GB virtual memory space is used
1382	  by the kernel to permanently map as much physical memory as
1383	  possible.
1384
1385	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1386	  answer "4GB" here.
1387
1388	  If more than 4 Gigabytes is used then answer "64GB" here. This
1389	  selection turns Intel PAE (Physical Address Extension) mode on.
1390	  PAE implements 3-level paging on IA32 processors. PAE is fully
1391	  supported by Linux, PAE mode is implemented on all recent Intel
1392	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1393	  then the kernel will not boot on CPUs that don't support PAE!
1394
1395	  The actual amount of total physical memory will either be
1396	  auto detected or can be forced by using a kernel command line option
1397	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1398	  your boot loader (lilo or loadlin) about how to pass options to the
1399	  kernel at boot time.)
1400
1401	  If unsure, say "off".
1402
1403config HIGHMEM4G
1404	bool "4GB"
1405	help
1406	  Select this if you have a 32-bit processor and between 1 and 4
1407	  gigabytes of physical RAM.
1408
1409config HIGHMEM64G
1410	bool "64GB"
1411	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1412	select X86_PAE
1413	help
1414	  Select this if you have a 32-bit processor and more than 4
1415	  gigabytes of physical RAM.
1416
1417endchoice
1418
1419choice
1420	prompt "Memory split" if EXPERT
1421	default VMSPLIT_3G
1422	depends on X86_32
1423	help
1424	  Select the desired split between kernel and user memory.
1425
1426	  If the address range available to the kernel is less than the
1427	  physical memory installed, the remaining memory will be available
1428	  as "high memory". Accessing high memory is a little more costly
1429	  than low memory, as it needs to be mapped into the kernel first.
1430	  Note that increasing the kernel address space limits the range
1431	  available to user programs, making the address space there
1432	  tighter.  Selecting anything other than the default 3G/1G split
1433	  will also likely make your kernel incompatible with binary-only
1434	  kernel modules.
1435
1436	  If you are not absolutely sure what you are doing, leave this
1437	  option alone!
1438
1439	config VMSPLIT_3G
1440		bool "3G/1G user/kernel split"
1441	config VMSPLIT_3G_OPT
1442		depends on !X86_PAE
1443		bool "3G/1G user/kernel split (for full 1G low memory)"
1444	config VMSPLIT_2G
1445		bool "2G/2G user/kernel split"
1446	config VMSPLIT_2G_OPT
1447		depends on !X86_PAE
1448		bool "2G/2G user/kernel split (for full 2G low memory)"
1449	config VMSPLIT_1G
1450		bool "1G/3G user/kernel split"
1451endchoice
1452
1453config PAGE_OFFSET
1454	hex
1455	default 0xB0000000 if VMSPLIT_3G_OPT
1456	default 0x80000000 if VMSPLIT_2G
1457	default 0x78000000 if VMSPLIT_2G_OPT
1458	default 0x40000000 if VMSPLIT_1G
1459	default 0xC0000000
1460	depends on X86_32
1461
1462config HIGHMEM
1463	def_bool y
1464	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1465
1466config X86_PAE
1467	bool "PAE (Physical Address Extension) Support"
1468	depends on X86_32 && !HIGHMEM4G
1469	select PHYS_ADDR_T_64BIT
1470	select SWIOTLB
1471	help
1472	  PAE is required for NX support, and furthermore enables
1473	  larger swapspace support for non-overcommit purposes. It
1474	  has the cost of more pagetable lookup overhead, and also
1475	  consumes more pagetable space per process.
1476
1477config X86_5LEVEL
1478	bool "Enable 5-level page tables support"
1479	default y
1480	select DYNAMIC_MEMORY_LAYOUT
1481	select SPARSEMEM_VMEMMAP
1482	depends on X86_64
1483	help
1484	  5-level paging enables access to larger address space:
1485	  upto 128 PiB of virtual address space and 4 PiB of
1486	  physical address space.
1487
1488	  It will be supported by future Intel CPUs.
1489
1490	  A kernel with the option enabled can be booted on machines that
1491	  support 4- or 5-level paging.
1492
1493	  See Documentation/x86/x86_64/5level-paging.rst for more
1494	  information.
1495
1496	  Say N if unsure.
1497
1498config X86_DIRECT_GBPAGES
1499	def_bool y
1500	depends on X86_64
1501	help
1502	  Certain kernel features effectively disable kernel
1503	  linear 1 GB mappings (even if the CPU otherwise
1504	  supports them), so don't confuse the user by printing
1505	  that we have them enabled.
1506
1507config X86_CPA_STATISTICS
1508	bool "Enable statistic for Change Page Attribute"
1509	depends on DEBUG_FS
1510	help
1511	  Expose statistics about the Change Page Attribute mechanism, which
1512	  helps to determine the effectiveness of preserving large and huge
1513	  page mappings when mapping protections are changed.
1514
1515config X86_MEM_ENCRYPT
1516	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1517	select DYNAMIC_PHYSICAL_MASK
1518	select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1519	def_bool n
1520
1521config AMD_MEM_ENCRYPT
1522	bool "AMD Secure Memory Encryption (SME) support"
1523	depends on X86_64 && CPU_SUP_AMD
1524	select DMA_COHERENT_POOL
1525	select ARCH_USE_MEMREMAP_PROT
1526	select INSTRUCTION_DECODER
1527	select ARCH_HAS_CC_PLATFORM
1528	select X86_MEM_ENCRYPT
1529	help
1530	  Say yes to enable support for the encryption of system memory.
1531	  This requires an AMD processor that supports Secure Memory
1532	  Encryption (SME).
1533
1534config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1535	bool "Activate AMD Secure Memory Encryption (SME) by default"
1536	depends on AMD_MEM_ENCRYPT
1537	help
1538	  Say yes to have system memory encrypted by default if running on
1539	  an AMD processor that supports Secure Memory Encryption (SME).
1540
1541	  If set to Y, then the encryption of system memory can be
1542	  deactivated with the mem_encrypt=off command line option.
1543
1544	  If set to N, then the encryption of system memory can be
1545	  activated with the mem_encrypt=on command line option.
1546
1547# Common NUMA Features
1548config NUMA
1549	bool "NUMA Memory Allocation and Scheduler Support"
1550	depends on SMP
1551	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1552	default y if X86_BIGSMP
1553	select USE_PERCPU_NUMA_NODE_ID
1554	help
1555	  Enable NUMA (Non-Uniform Memory Access) support.
1556
1557	  The kernel will try to allocate memory used by a CPU on the
1558	  local memory controller of the CPU and add some more
1559	  NUMA awareness to the kernel.
1560
1561	  For 64-bit this is recommended if the system is Intel Core i7
1562	  (or later), AMD Opteron, or EM64T NUMA.
1563
1564	  For 32-bit this is only needed if you boot a 32-bit
1565	  kernel on a 64-bit NUMA platform.
1566
1567	  Otherwise, you should say N.
1568
1569config AMD_NUMA
1570	def_bool y
1571	prompt "Old style AMD Opteron NUMA detection"
1572	depends on X86_64 && NUMA && PCI
1573	help
1574	  Enable AMD NUMA node topology detection.  You should say Y here if
1575	  you have a multi processor AMD system. This uses an old method to
1576	  read the NUMA configuration directly from the builtin Northbridge
1577	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1578	  which also takes priority if both are compiled in.
1579
1580config X86_64_ACPI_NUMA
1581	def_bool y
1582	prompt "ACPI NUMA detection"
1583	depends on X86_64 && NUMA && ACPI && PCI
1584	select ACPI_NUMA
1585	help
1586	  Enable ACPI SRAT based node topology detection.
1587
1588config NUMA_EMU
1589	bool "NUMA emulation"
1590	depends on NUMA
1591	help
1592	  Enable NUMA emulation. A flat machine will be split
1593	  into virtual nodes when booted with "numa=fake=N", where N is the
1594	  number of nodes. This is only useful for debugging.
1595
1596config NODES_SHIFT
1597	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1598	range 1 10
1599	default "10" if MAXSMP
1600	default "6" if X86_64
1601	default "3"
1602	depends on NUMA
1603	help
1604	  Specify the maximum number of NUMA Nodes available on the target
1605	  system.  Increases memory reserved to accommodate various tables.
1606
1607config ARCH_FLATMEM_ENABLE
1608	def_bool y
1609	depends on X86_32 && !NUMA
1610
1611config ARCH_SPARSEMEM_ENABLE
1612	def_bool y
1613	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1614	select SPARSEMEM_STATIC if X86_32
1615	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1616
1617config ARCH_SPARSEMEM_DEFAULT
1618	def_bool X86_64 || (NUMA && X86_32)
1619
1620config ARCH_SELECT_MEMORY_MODEL
1621	def_bool y
1622	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1623
1624config ARCH_MEMORY_PROBE
1625	bool "Enable sysfs memory/probe interface"
1626	depends on MEMORY_HOTPLUG
1627	help
1628	  This option enables a sysfs memory/probe interface for testing.
1629	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1630	  If you are unsure how to answer this question, answer N.
1631
1632config ARCH_PROC_KCORE_TEXT
1633	def_bool y
1634	depends on X86_64 && PROC_KCORE
1635
1636config ILLEGAL_POINTER_VALUE
1637	hex
1638	default 0 if X86_32
1639	default 0xdead000000000000 if X86_64
1640
1641config X86_PMEM_LEGACY_DEVICE
1642	bool
1643
1644config X86_PMEM_LEGACY
1645	tristate "Support non-standard NVDIMMs and ADR protected memory"
1646	depends on PHYS_ADDR_T_64BIT
1647	depends on BLK_DEV
1648	select X86_PMEM_LEGACY_DEVICE
1649	select NUMA_KEEP_MEMINFO if NUMA
1650	select LIBNVDIMM
1651	help
1652	  Treat memory marked using the non-standard e820 type of 12 as used
1653	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1654	  The kernel will offer these regions to the 'pmem' driver so
1655	  they can be used for persistent storage.
1656
1657	  Say Y if unsure.
1658
1659config HIGHPTE
1660	bool "Allocate 3rd-level pagetables from highmem"
1661	depends on HIGHMEM
1662	help
1663	  The VM uses one page table entry for each page of physical memory.
1664	  For systems with a lot of RAM, this can be wasteful of precious
1665	  low memory.  Setting this option will put user-space page table
1666	  entries in high memory.
1667
1668config X86_CHECK_BIOS_CORRUPTION
1669	bool "Check for low memory corruption"
1670	help
1671	  Periodically check for memory corruption in low memory, which
1672	  is suspected to be caused by BIOS.  Even when enabled in the
1673	  configuration, it is disabled at runtime.  Enable it by
1674	  setting "memory_corruption_check=1" on the kernel command
1675	  line.  By default it scans the low 64k of memory every 60
1676	  seconds; see the memory_corruption_check_size and
1677	  memory_corruption_check_period parameters in
1678	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1679
1680	  When enabled with the default parameters, this option has
1681	  almost no overhead, as it reserves a relatively small amount
1682	  of memory and scans it infrequently.  It both detects corruption
1683	  and prevents it from affecting the running system.
1684
1685	  It is, however, intended as a diagnostic tool; if repeatable
1686	  BIOS-originated corruption always affects the same memory,
1687	  you can use memmap= to prevent the kernel from using that
1688	  memory.
1689
1690config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1691	bool "Set the default setting of memory_corruption_check"
1692	depends on X86_CHECK_BIOS_CORRUPTION
1693	default y
1694	help
1695	  Set whether the default state of memory_corruption_check is
1696	  on or off.
1697
1698config MATH_EMULATION
1699	bool
1700	depends on MODIFY_LDT_SYSCALL
1701	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1702	help
1703	  Linux can emulate a math coprocessor (used for floating point
1704	  operations) if you don't have one. 486DX and Pentium processors have
1705	  a math coprocessor built in, 486SX and 386 do not, unless you added
1706	  a 487DX or 387, respectively. (The messages during boot time can
1707	  give you some hints here ["man dmesg"].) Everyone needs either a
1708	  coprocessor or this emulation.
1709
1710	  If you don't have a math coprocessor, you need to say Y here; if you
1711	  say Y here even though you have a coprocessor, the coprocessor will
1712	  be used nevertheless. (This behavior can be changed with the kernel
1713	  command line option "no387", which comes handy if your coprocessor
1714	  is broken. Try "man bootparam" or see the documentation of your boot
1715	  loader (lilo or loadlin) about how to pass options to the kernel at
1716	  boot time.) This means that it is a good idea to say Y here if you
1717	  intend to use this kernel on different machines.
1718
1719	  More information about the internals of the Linux math coprocessor
1720	  emulation can be found in <file:arch/x86/math-emu/README>.
1721
1722	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1723	  kernel, it won't hurt.
1724
1725config MTRR
1726	def_bool y
1727	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1728	help
1729	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1730	  the Memory Type Range Registers (MTRRs) may be used to control
1731	  processor access to memory ranges. This is most useful if you have
1732	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1733	  allows bus write transfers to be combined into a larger transfer
1734	  before bursting over the PCI/AGP bus. This can increase performance
1735	  of image write operations 2.5 times or more. Saying Y here creates a
1736	  /proc/mtrr file which may be used to manipulate your processor's
1737	  MTRRs. Typically the X server should use this.
1738
1739	  This code has a reasonably generic interface so that similar
1740	  control registers on other processors can be easily supported
1741	  as well:
1742
1743	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1744	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1745	  these, the ARRs are used to emulate the MTRRs.
1746	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1747	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1748	  write-combining. All of these processors are supported by this code
1749	  and it makes sense to say Y here if you have one of them.
1750
1751	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1752	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1753	  can lead to all sorts of problems, so it's good to say Y here.
1754
1755	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1756	  just add about 9 KB to your kernel.
1757
1758	  See <file:Documentation/x86/mtrr.rst> for more information.
1759
1760config MTRR_SANITIZER
1761	def_bool y
1762	prompt "MTRR cleanup support"
1763	depends on MTRR
1764	help
1765	  Convert MTRR layout from continuous to discrete, so X drivers can
1766	  add writeback entries.
1767
1768	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1769	  The largest mtrr entry size for a continuous block can be set with
1770	  mtrr_chunk_size.
1771
1772	  If unsure, say Y.
1773
1774config MTRR_SANITIZER_ENABLE_DEFAULT
1775	int "MTRR cleanup enable value (0-1)"
1776	range 0 1
1777	default "0"
1778	depends on MTRR_SANITIZER
1779	help
1780	  Enable mtrr cleanup default value
1781
1782config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1783	int "MTRR cleanup spare reg num (0-7)"
1784	range 0 7
1785	default "1"
1786	depends on MTRR_SANITIZER
1787	help
1788	  mtrr cleanup spare entries default, it can be changed via
1789	  mtrr_spare_reg_nr=N on the kernel command line.
1790
1791config X86_PAT
1792	def_bool y
1793	prompt "x86 PAT support" if EXPERT
1794	depends on MTRR
1795	help
1796	  Use PAT attributes to setup page level cache control.
1797
1798	  PATs are the modern equivalents of MTRRs and are much more
1799	  flexible than MTRRs.
1800
1801	  Say N here if you see bootup problems (boot crash, boot hang,
1802	  spontaneous reboots) or a non-working video driver.
1803
1804	  If unsure, say Y.
1805
1806config ARCH_USES_PG_UNCACHED
1807	def_bool y
1808	depends on X86_PAT
1809
1810config ARCH_RANDOM
1811	def_bool y
1812	prompt "x86 architectural random number generator" if EXPERT
1813	help
1814	  Enable the x86 architectural RDRAND instruction
1815	  (Intel Bull Mountain technology) to generate random numbers.
1816	  If supported, this is a high bandwidth, cryptographically
1817	  secure hardware random number generator.
1818
1819config X86_SMAP
1820	def_bool y
1821	prompt "Supervisor Mode Access Prevention" if EXPERT
1822	help
1823	  Supervisor Mode Access Prevention (SMAP) is a security
1824	  feature in newer Intel processors.  There is a small
1825	  performance cost if this enabled and turned on; there is
1826	  also a small increase in the kernel size if this is enabled.
1827
1828	  If unsure, say Y.
1829
1830config X86_UMIP
1831	def_bool y
1832	prompt "User Mode Instruction Prevention" if EXPERT
1833	help
1834	  User Mode Instruction Prevention (UMIP) is a security feature in
1835	  some x86 processors. If enabled, a general protection fault is
1836	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1837	  executed in user mode. These instructions unnecessarily expose
1838	  information about the hardware state.
1839
1840	  The vast majority of applications do not use these instructions.
1841	  For the very few that do, software emulation is provided in
1842	  specific cases in protected and virtual-8086 modes. Emulated
1843	  results are dummy.
1844
1845config CC_HAS_IBT
1846	# GCC >= 9 and binutils >= 2.29
1847	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1848	# Clang/LLVM >= 14
1849	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1850	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1851	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1852		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1853		  $(as-instr,endbr64)
1854
1855config X86_KERNEL_IBT
1856	prompt "Indirect Branch Tracking"
1857	bool
1858	depends on X86_64 && CC_HAS_IBT && STACK_VALIDATION
1859	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1860	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1861	help
1862	  Build the kernel with support for Indirect Branch Tracking, a
1863	  hardware support course-grain forward-edge Control Flow Integrity
1864	  protection. It enforces that all indirect calls must land on
1865	  an ENDBR instruction, as such, the compiler will instrument the
1866	  code with them to make this happen.
1867
1868	  In addition to building the kernel with IBT, seal all functions that
1869	  are not indirect call targets, avoiding them ever becomming one.
1870
1871	  This requires LTO like objtool runs and will slow down the build. It
1872	  does significantly reduce the number of ENDBR instructions in the
1873	  kernel image.
1874
1875config X86_INTEL_MEMORY_PROTECTION_KEYS
1876	prompt "Memory Protection Keys"
1877	def_bool y
1878	# Note: only available in 64-bit mode
1879	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1880	select ARCH_USES_HIGH_VMA_FLAGS
1881	select ARCH_HAS_PKEYS
1882	help
1883	  Memory Protection Keys provides a mechanism for enforcing
1884	  page-based protections, but without requiring modification of the
1885	  page tables when an application changes protection domains.
1886
1887	  For details, see Documentation/core-api/protection-keys.rst
1888
1889	  If unsure, say y.
1890
1891choice
1892	prompt "TSX enable mode"
1893	depends on CPU_SUP_INTEL
1894	default X86_INTEL_TSX_MODE_OFF
1895	help
1896	  Intel's TSX (Transactional Synchronization Extensions) feature
1897	  allows to optimize locking protocols through lock elision which
1898	  can lead to a noticeable performance boost.
1899
1900	  On the other hand it has been shown that TSX can be exploited
1901	  to form side channel attacks (e.g. TAA) and chances are there
1902	  will be more of those attacks discovered in the future.
1903
1904	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1905	  might override this decision by tsx=on the command line parameter.
1906	  Even with TSX enabled, the kernel will attempt to enable the best
1907	  possible TAA mitigation setting depending on the microcode available
1908	  for the particular machine.
1909
1910	  This option allows to set the default tsx mode between tsx=on, =off
1911	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1912	  details.
1913
1914	  Say off if not sure, auto if TSX is in use but it should be used on safe
1915	  platforms or on if TSX is in use and the security aspect of tsx is not
1916	  relevant.
1917
1918config X86_INTEL_TSX_MODE_OFF
1919	bool "off"
1920	help
1921	  TSX is disabled if possible - equals to tsx=off command line parameter.
1922
1923config X86_INTEL_TSX_MODE_ON
1924	bool "on"
1925	help
1926	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1927	  line parameter.
1928
1929config X86_INTEL_TSX_MODE_AUTO
1930	bool "auto"
1931	help
1932	  TSX is enabled on TSX capable HW that is believed to be safe against
1933	  side channel attacks- equals the tsx=auto command line parameter.
1934endchoice
1935
1936config X86_SGX
1937	bool "Software Guard eXtensions (SGX)"
1938	depends on X86_64 && CPU_SUP_INTEL
1939	depends on CRYPTO=y
1940	depends on CRYPTO_SHA256=y
1941	select SRCU
1942	select MMU_NOTIFIER
1943	select NUMA_KEEP_MEMINFO if NUMA
1944	select XARRAY_MULTI
1945	help
1946	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1947	  that can be used by applications to set aside private regions of code
1948	  and data, referred to as enclaves. An enclave's private memory can
1949	  only be accessed by code running within the enclave. Accesses from
1950	  outside the enclave, including other enclaves, are disallowed by
1951	  hardware.
1952
1953	  If unsure, say N.
1954
1955config EFI
1956	bool "EFI runtime service support"
1957	depends on ACPI
1958	select UCS2_STRING
1959	select EFI_RUNTIME_WRAPPERS
1960	select ARCH_USE_MEMREMAP_PROT
1961	help
1962	  This enables the kernel to use EFI runtime services that are
1963	  available (such as the EFI variable services).
1964
1965	  This option is only useful on systems that have EFI firmware.
1966	  In addition, you should use the latest ELILO loader available
1967	  at <http://elilo.sourceforge.net> in order to take advantage
1968	  of EFI runtime services. However, even with this option, the
1969	  resultant kernel should continue to boot on existing non-EFI
1970	  platforms.
1971
1972config EFI_STUB
1973	bool "EFI stub support"
1974	depends on EFI
1975	depends on $(cc-option,-mabi=ms) || X86_32
1976	select RELOCATABLE
1977	help
1978	  This kernel feature allows a bzImage to be loaded directly
1979	  by EFI firmware without the use of a bootloader.
1980
1981	  See Documentation/admin-guide/efi-stub.rst for more information.
1982
1983config EFI_MIXED
1984	bool "EFI mixed-mode support"
1985	depends on EFI_STUB && X86_64
1986	help
1987	   Enabling this feature allows a 64-bit kernel to be booted
1988	   on a 32-bit firmware, provided that your CPU supports 64-bit
1989	   mode.
1990
1991	   Note that it is not possible to boot a mixed-mode enabled
1992	   kernel via the EFI boot stub - a bootloader that supports
1993	   the EFI handover protocol must be used.
1994
1995	   If unsure, say N.
1996
1997source "kernel/Kconfig.hz"
1998
1999config KEXEC
2000	bool "kexec system call"
2001	select KEXEC_CORE
2002	help
2003	  kexec is a system call that implements the ability to shutdown your
2004	  current kernel, and to start another kernel.  It is like a reboot
2005	  but it is independent of the system firmware.   And like a reboot
2006	  you can start any kernel with it, not just Linux.
2007
2008	  The name comes from the similarity to the exec system call.
2009
2010	  It is an ongoing process to be certain the hardware in a machine
2011	  is properly shutdown, so do not be surprised if this code does not
2012	  initially work for you.  As of this writing the exact hardware
2013	  interface is strongly in flux, so no good recommendation can be
2014	  made.
2015
2016config KEXEC_FILE
2017	bool "kexec file based system call"
2018	select KEXEC_CORE
2019	select BUILD_BIN2C
2020	depends on X86_64
2021	depends on CRYPTO=y
2022	depends on CRYPTO_SHA256=y
2023	help
2024	  This is new version of kexec system call. This system call is
2025	  file based and takes file descriptors as system call argument
2026	  for kernel and initramfs as opposed to list of segments as
2027	  accepted by previous system call.
2028
2029config ARCH_HAS_KEXEC_PURGATORY
2030	def_bool KEXEC_FILE
2031
2032config KEXEC_SIG
2033	bool "Verify kernel signature during kexec_file_load() syscall"
2034	depends on KEXEC_FILE
2035	help
2036
2037	  This option makes the kexec_file_load() syscall check for a valid
2038	  signature of the kernel image.  The image can still be loaded without
2039	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2040	  there's a signature that we can check, then it must be valid.
2041
2042	  In addition to this option, you need to enable signature
2043	  verification for the corresponding kernel image type being
2044	  loaded in order for this to work.
2045
2046config KEXEC_SIG_FORCE
2047	bool "Require a valid signature in kexec_file_load() syscall"
2048	depends on KEXEC_SIG
2049	help
2050	  This option makes kernel signature verification mandatory for
2051	  the kexec_file_load() syscall.
2052
2053config KEXEC_BZIMAGE_VERIFY_SIG
2054	bool "Enable bzImage signature verification support"
2055	depends on KEXEC_SIG
2056	depends on SIGNED_PE_FILE_VERIFICATION
2057	select SYSTEM_TRUSTED_KEYRING
2058	help
2059	  Enable bzImage signature verification support.
2060
2061config CRASH_DUMP
2062	bool "kernel crash dumps"
2063	depends on X86_64 || (X86_32 && HIGHMEM)
2064	help
2065	  Generate crash dump after being started by kexec.
2066	  This should be normally only set in special crash dump kernels
2067	  which are loaded in the main kernel with kexec-tools into
2068	  a specially reserved region and then later executed after
2069	  a crash by kdump/kexec. The crash dump kernel must be compiled
2070	  to a memory address not used by the main kernel or BIOS using
2071	  PHYSICAL_START, or it must be built as a relocatable image
2072	  (CONFIG_RELOCATABLE=y).
2073	  For more details see Documentation/admin-guide/kdump/kdump.rst
2074
2075config KEXEC_JUMP
2076	bool "kexec jump"
2077	depends on KEXEC && HIBERNATION
2078	help
2079	  Jump between original kernel and kexeced kernel and invoke
2080	  code in physical address mode via KEXEC
2081
2082config PHYSICAL_START
2083	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2084	default "0x1000000"
2085	help
2086	  This gives the physical address where the kernel is loaded.
2087
2088	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2089	  bzImage will decompress itself to above physical address and
2090	  run from there. Otherwise, bzImage will run from the address where
2091	  it has been loaded by the boot loader and will ignore above physical
2092	  address.
2093
2094	  In normal kdump cases one does not have to set/change this option
2095	  as now bzImage can be compiled as a completely relocatable image
2096	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2097	  address. This option is mainly useful for the folks who don't want
2098	  to use a bzImage for capturing the crash dump and want to use a
2099	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2100	  to be specifically compiled to run from a specific memory area
2101	  (normally a reserved region) and this option comes handy.
2102
2103	  So if you are using bzImage for capturing the crash dump,
2104	  leave the value here unchanged to 0x1000000 and set
2105	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2106	  for capturing the crash dump change this value to start of
2107	  the reserved region.  In other words, it can be set based on
2108	  the "X" value as specified in the "crashkernel=YM@XM"
2109	  command line boot parameter passed to the panic-ed
2110	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2111	  for more details about crash dumps.
2112
2113	  Usage of bzImage for capturing the crash dump is recommended as
2114	  one does not have to build two kernels. Same kernel can be used
2115	  as production kernel and capture kernel. Above option should have
2116	  gone away after relocatable bzImage support is introduced. But it
2117	  is present because there are users out there who continue to use
2118	  vmlinux for dump capture. This option should go away down the
2119	  line.
2120
2121	  Don't change this unless you know what you are doing.
2122
2123config RELOCATABLE
2124	bool "Build a relocatable kernel"
2125	default y
2126	help
2127	  This builds a kernel image that retains relocation information
2128	  so it can be loaded someplace besides the default 1MB.
2129	  The relocations tend to make the kernel binary about 10% larger,
2130	  but are discarded at runtime.
2131
2132	  One use is for the kexec on panic case where the recovery kernel
2133	  must live at a different physical address than the primary
2134	  kernel.
2135
2136	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2137	  it has been loaded at and the compile time physical address
2138	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2139
2140config RANDOMIZE_BASE
2141	bool "Randomize the address of the kernel image (KASLR)"
2142	depends on RELOCATABLE
2143	default y
2144	help
2145	  In support of Kernel Address Space Layout Randomization (KASLR),
2146	  this randomizes the physical address at which the kernel image
2147	  is decompressed and the virtual address where the kernel
2148	  image is mapped, as a security feature that deters exploit
2149	  attempts relying on knowledge of the location of kernel
2150	  code internals.
2151
2152	  On 64-bit, the kernel physical and virtual addresses are
2153	  randomized separately. The physical address will be anywhere
2154	  between 16MB and the top of physical memory (up to 64TB). The
2155	  virtual address will be randomized from 16MB up to 1GB (9 bits
2156	  of entropy). Note that this also reduces the memory space
2157	  available to kernel modules from 1.5GB to 1GB.
2158
2159	  On 32-bit, the kernel physical and virtual addresses are
2160	  randomized together. They will be randomized from 16MB up to
2161	  512MB (8 bits of entropy).
2162
2163	  Entropy is generated using the RDRAND instruction if it is
2164	  supported. If RDTSC is supported, its value is mixed into
2165	  the entropy pool as well. If neither RDRAND nor RDTSC are
2166	  supported, then entropy is read from the i8254 timer. The
2167	  usable entropy is limited by the kernel being built using
2168	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2169	  minimum of 2MB. As a result, only 10 bits of entropy are
2170	  theoretically possible, but the implementations are further
2171	  limited due to memory layouts.
2172
2173	  If unsure, say Y.
2174
2175# Relocation on x86 needs some additional build support
2176config X86_NEED_RELOCS
2177	def_bool y
2178	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2179
2180config PHYSICAL_ALIGN
2181	hex "Alignment value to which kernel should be aligned"
2182	default "0x200000"
2183	range 0x2000 0x1000000 if X86_32
2184	range 0x200000 0x1000000 if X86_64
2185	help
2186	  This value puts the alignment restrictions on physical address
2187	  where kernel is loaded and run from. Kernel is compiled for an
2188	  address which meets above alignment restriction.
2189
2190	  If bootloader loads the kernel at a non-aligned address and
2191	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2192	  address aligned to above value and run from there.
2193
2194	  If bootloader loads the kernel at a non-aligned address and
2195	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2196	  load address and decompress itself to the address it has been
2197	  compiled for and run from there. The address for which kernel is
2198	  compiled already meets above alignment restrictions. Hence the
2199	  end result is that kernel runs from a physical address meeting
2200	  above alignment restrictions.
2201
2202	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2203	  this value must be a multiple of 0x200000.
2204
2205	  Don't change this unless you know what you are doing.
2206
2207config DYNAMIC_MEMORY_LAYOUT
2208	bool
2209	help
2210	  This option makes base addresses of vmalloc and vmemmap as well as
2211	  __PAGE_OFFSET movable during boot.
2212
2213config RANDOMIZE_MEMORY
2214	bool "Randomize the kernel memory sections"
2215	depends on X86_64
2216	depends on RANDOMIZE_BASE
2217	select DYNAMIC_MEMORY_LAYOUT
2218	default RANDOMIZE_BASE
2219	help
2220	   Randomizes the base virtual address of kernel memory sections
2221	   (physical memory mapping, vmalloc & vmemmap). This security feature
2222	   makes exploits relying on predictable memory locations less reliable.
2223
2224	   The order of allocations remains unchanged. Entropy is generated in
2225	   the same way as RANDOMIZE_BASE. Current implementation in the optimal
2226	   configuration have in average 30,000 different possible virtual
2227	   addresses for each memory section.
2228
2229	   If unsure, say Y.
2230
2231config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2232	hex "Physical memory mapping padding" if EXPERT
2233	depends on RANDOMIZE_MEMORY
2234	default "0xa" if MEMORY_HOTPLUG
2235	default "0x0"
2236	range 0x1 0x40 if MEMORY_HOTPLUG
2237	range 0x0 0x40
2238	help
2239	   Define the padding in terabytes added to the existing physical
2240	   memory size during kernel memory randomization. It is useful
2241	   for memory hotplug support but reduces the entropy available for
2242	   address randomization.
2243
2244	   If unsure, leave at the default value.
2245
2246config HOTPLUG_CPU
2247	def_bool y
2248	depends on SMP
2249
2250config BOOTPARAM_HOTPLUG_CPU0
2251	bool "Set default setting of cpu0_hotpluggable"
2252	depends on HOTPLUG_CPU
2253	help
2254	  Set whether default state of cpu0_hotpluggable is on or off.
2255
2256	  Say Y here to enable CPU0 hotplug by default. If this switch
2257	  is turned on, there is no need to give cpu0_hotplug kernel
2258	  parameter and the CPU0 hotplug feature is enabled by default.
2259
2260	  Please note: there are two known CPU0 dependencies if you want
2261	  to enable the CPU0 hotplug feature either by this switch or by
2262	  cpu0_hotplug kernel parameter.
2263
2264	  First, resume from hibernate or suspend always starts from CPU0.
2265	  So hibernate and suspend are prevented if CPU0 is offline.
2266
2267	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2268	  offline if any interrupt can not migrate out of CPU0. There may
2269	  be other CPU0 dependencies.
2270
2271	  Please make sure the dependencies are under your control before
2272	  you enable this feature.
2273
2274	  Say N if you don't want to enable CPU0 hotplug feature by default.
2275	  You still can enable the CPU0 hotplug feature at boot by kernel
2276	  parameter cpu0_hotplug.
2277
2278config DEBUG_HOTPLUG_CPU0
2279	def_bool n
2280	prompt "Debug CPU0 hotplug"
2281	depends on HOTPLUG_CPU
2282	help
2283	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2284	  soon as possible and boots up userspace with CPU0 offlined. User
2285	  can online CPU0 back after boot time.
2286
2287	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2288	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2289	  compilation or giving cpu0_hotplug kernel parameter at boot.
2290
2291	  If unsure, say N.
2292
2293config COMPAT_VDSO
2294	def_bool n
2295	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2296	depends on COMPAT_32
2297	help
2298	  Certain buggy versions of glibc will crash if they are
2299	  presented with a 32-bit vDSO that is not mapped at the address
2300	  indicated in its segment table.
2301
2302	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2303	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2304	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2305	  the only released version with the bug, but OpenSUSE 9
2306	  contains a buggy "glibc 2.3.2".
2307
2308	  The symptom of the bug is that everything crashes on startup, saying:
2309	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2310
2311	  Saying Y here changes the default value of the vdso32 boot
2312	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2313	  This works around the glibc bug but hurts performance.
2314
2315	  If unsure, say N: if you are compiling your own kernel, you
2316	  are unlikely to be using a buggy version of glibc.
2317
2318choice
2319	prompt "vsyscall table for legacy applications"
2320	depends on X86_64
2321	default LEGACY_VSYSCALL_XONLY
2322	help
2323	  Legacy user code that does not know how to find the vDSO expects
2324	  to be able to issue three syscalls by calling fixed addresses in
2325	  kernel space. Since this location is not randomized with ASLR,
2326	  it can be used to assist security vulnerability exploitation.
2327
2328	  This setting can be changed at boot time via the kernel command
2329	  line parameter vsyscall=[emulate|xonly|none].
2330
2331	  On a system with recent enough glibc (2.14 or newer) and no
2332	  static binaries, you can say None without a performance penalty
2333	  to improve security.
2334
2335	  If unsure, select "Emulate execution only".
2336
2337	config LEGACY_VSYSCALL_EMULATE
2338		bool "Full emulation"
2339		help
2340		  The kernel traps and emulates calls into the fixed vsyscall
2341		  address mapping. This makes the mapping non-executable, but
2342		  it still contains readable known contents, which could be
2343		  used in certain rare security vulnerability exploits. This
2344		  configuration is recommended when using legacy userspace
2345		  that still uses vsyscalls along with legacy binary
2346		  instrumentation tools that require code to be readable.
2347
2348		  An example of this type of legacy userspace is running
2349		  Pin on an old binary that still uses vsyscalls.
2350
2351	config LEGACY_VSYSCALL_XONLY
2352		bool "Emulate execution only"
2353		help
2354		  The kernel traps and emulates calls into the fixed vsyscall
2355		  address mapping and does not allow reads.  This
2356		  configuration is recommended when userspace might use the
2357		  legacy vsyscall area but support for legacy binary
2358		  instrumentation of legacy code is not needed.  It mitigates
2359		  certain uses of the vsyscall area as an ASLR-bypassing
2360		  buffer.
2361
2362	config LEGACY_VSYSCALL_NONE
2363		bool "None"
2364		help
2365		  There will be no vsyscall mapping at all. This will
2366		  eliminate any risk of ASLR bypass due to the vsyscall
2367		  fixed address mapping. Attempts to use the vsyscalls
2368		  will be reported to dmesg, so that either old or
2369		  malicious userspace programs can be identified.
2370
2371endchoice
2372
2373config CMDLINE_BOOL
2374	bool "Built-in kernel command line"
2375	help
2376	  Allow for specifying boot arguments to the kernel at
2377	  build time.  On some systems (e.g. embedded ones), it is
2378	  necessary or convenient to provide some or all of the
2379	  kernel boot arguments with the kernel itself (that is,
2380	  to not rely on the boot loader to provide them.)
2381
2382	  To compile command line arguments into the kernel,
2383	  set this option to 'Y', then fill in the
2384	  boot arguments in CONFIG_CMDLINE.
2385
2386	  Systems with fully functional boot loaders (i.e. non-embedded)
2387	  should leave this option set to 'N'.
2388
2389config CMDLINE
2390	string "Built-in kernel command string"
2391	depends on CMDLINE_BOOL
2392	default ""
2393	help
2394	  Enter arguments here that should be compiled into the kernel
2395	  image and used at boot time.  If the boot loader provides a
2396	  command line at boot time, it is appended to this string to
2397	  form the full kernel command line, when the system boots.
2398
2399	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2400	  change this behavior.
2401
2402	  In most cases, the command line (whether built-in or provided
2403	  by the boot loader) should specify the device for the root
2404	  file system.
2405
2406config CMDLINE_OVERRIDE
2407	bool "Built-in command line overrides boot loader arguments"
2408	depends on CMDLINE_BOOL && CMDLINE != ""
2409	help
2410	  Set this option to 'Y' to have the kernel ignore the boot loader
2411	  command line, and use ONLY the built-in command line.
2412
2413	  This is used to work around broken boot loaders.  This should
2414	  be set to 'N' under normal conditions.
2415
2416config MODIFY_LDT_SYSCALL
2417	bool "Enable the LDT (local descriptor table)" if EXPERT
2418	default y
2419	help
2420	  Linux can allow user programs to install a per-process x86
2421	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2422	  call.  This is required to run 16-bit or segmented code such as
2423	  DOSEMU or some Wine programs.  It is also used by some very old
2424	  threading libraries.
2425
2426	  Enabling this feature adds a small amount of overhead to
2427	  context switches and increases the low-level kernel attack
2428	  surface.  Disabling it removes the modify_ldt(2) system call.
2429
2430	  Saying 'N' here may make sense for embedded or server kernels.
2431
2432config STRICT_SIGALTSTACK_SIZE
2433	bool "Enforce strict size checking for sigaltstack"
2434	depends on DYNAMIC_SIGFRAME
2435	help
2436	  For historical reasons MINSIGSTKSZ is a constant which became
2437	  already too small with AVX512 support. Add a mechanism to
2438	  enforce strict checking of the sigaltstack size against the
2439	  real size of the FPU frame. This option enables the check
2440	  by default. It can also be controlled via the kernel command
2441	  line option 'strict_sas_size' independent of this config
2442	  switch. Enabling it might break existing applications which
2443	  allocate a too small sigaltstack but 'work' because they
2444	  never get a signal delivered.
2445
2446	  Say 'N' unless you want to really enforce this check.
2447
2448source "kernel/livepatch/Kconfig"
2449
2450endmenu
2451
2452config ARCH_HAS_ADD_PAGES
2453	def_bool y
2454	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2455
2456config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2457	def_bool y
2458
2459menu "Power management and ACPI options"
2460
2461config ARCH_HIBERNATION_HEADER
2462	def_bool y
2463	depends on HIBERNATION
2464
2465source "kernel/power/Kconfig"
2466
2467source "drivers/acpi/Kconfig"
2468
2469config X86_APM_BOOT
2470	def_bool y
2471	depends on APM
2472
2473menuconfig APM
2474	tristate "APM (Advanced Power Management) BIOS support"
2475	depends on X86_32 && PM_SLEEP
2476	help
2477	  APM is a BIOS specification for saving power using several different
2478	  techniques. This is mostly useful for battery powered laptops with
2479	  APM compliant BIOSes. If you say Y here, the system time will be
2480	  reset after a RESUME operation, the /proc/apm device will provide
2481	  battery status information, and user-space programs will receive
2482	  notification of APM "events" (e.g. battery status change).
2483
2484	  If you select "Y" here, you can disable actual use of the APM
2485	  BIOS by passing the "apm=off" option to the kernel at boot time.
2486
2487	  Note that the APM support is almost completely disabled for
2488	  machines with more than one CPU.
2489
2490	  In order to use APM, you will need supporting software. For location
2491	  and more information, read <file:Documentation/power/apm-acpi.rst>
2492	  and the Battery Powered Linux mini-HOWTO, available from
2493	  <http://www.tldp.org/docs.html#howto>.
2494
2495	  This driver does not spin down disk drives (see the hdparm(8)
2496	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2497	  VESA-compliant "green" monitors.
2498
2499	  This driver does not support the TI 4000M TravelMate and the ACER
2500	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2501	  desktop machines also don't have compliant BIOSes, and this driver
2502	  may cause those machines to panic during the boot phase.
2503
2504	  Generally, if you don't have a battery in your machine, there isn't
2505	  much point in using this driver and you should say N. If you get
2506	  random kernel OOPSes or reboots that don't seem to be related to
2507	  anything, try disabling/enabling this option (or disabling/enabling
2508	  APM in your BIOS).
2509
2510	  Some other things you should try when experiencing seemingly random,
2511	  "weird" problems:
2512
2513	  1) make sure that you have enough swap space and that it is
2514	  enabled.
2515	  2) pass the "no-hlt" option to the kernel
2516	  3) switch on floating point emulation in the kernel and pass
2517	  the "no387" option to the kernel
2518	  4) pass the "floppy=nodma" option to the kernel
2519	  5) pass the "mem=4M" option to the kernel (thereby disabling
2520	  all but the first 4 MB of RAM)
2521	  6) make sure that the CPU is not over clocked.
2522	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2523	  8) disable the cache from your BIOS settings
2524	  9) install a fan for the video card or exchange video RAM
2525	  10) install a better fan for the CPU
2526	  11) exchange RAM chips
2527	  12) exchange the motherboard.
2528
2529	  To compile this driver as a module, choose M here: the
2530	  module will be called apm.
2531
2532if APM
2533
2534config APM_IGNORE_USER_SUSPEND
2535	bool "Ignore USER SUSPEND"
2536	help
2537	  This option will ignore USER SUSPEND requests. On machines with a
2538	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2539	  series notebooks, it is necessary to say Y because of a BIOS bug.
2540
2541config APM_DO_ENABLE
2542	bool "Enable PM at boot time"
2543	help
2544	  Enable APM features at boot time. From page 36 of the APM BIOS
2545	  specification: "When disabled, the APM BIOS does not automatically
2546	  power manage devices, enter the Standby State, enter the Suspend
2547	  State, or take power saving steps in response to CPU Idle calls."
2548	  This driver will make CPU Idle calls when Linux is idle (unless this
2549	  feature is turned off -- see "Do CPU IDLE calls", below). This
2550	  should always save battery power, but more complicated APM features
2551	  will be dependent on your BIOS implementation. You may need to turn
2552	  this option off if your computer hangs at boot time when using APM
2553	  support, or if it beeps continuously instead of suspending. Turn
2554	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2555	  T400CDT. This is off by default since most machines do fine without
2556	  this feature.
2557
2558config APM_CPU_IDLE
2559	depends on CPU_IDLE
2560	bool "Make CPU Idle calls when idle"
2561	help
2562	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2563	  On some machines, this can activate improved power savings, such as
2564	  a slowed CPU clock rate, when the machine is idle. These idle calls
2565	  are made after the idle loop has run for some length of time (e.g.,
2566	  333 mS). On some machines, this will cause a hang at boot time or
2567	  whenever the CPU becomes idle. (On machines with more than one CPU,
2568	  this option does nothing.)
2569
2570config APM_DISPLAY_BLANK
2571	bool "Enable console blanking using APM"
2572	help
2573	  Enable console blanking using the APM. Some laptops can use this to
2574	  turn off the LCD backlight when the screen blanker of the Linux
2575	  virtual console blanks the screen. Note that this is only used by
2576	  the virtual console screen blanker, and won't turn off the backlight
2577	  when using the X Window system. This also doesn't have anything to
2578	  do with your VESA-compliant power-saving monitor. Further, this
2579	  option doesn't work for all laptops -- it might not turn off your
2580	  backlight at all, or it might print a lot of errors to the console,
2581	  especially if you are using gpm.
2582
2583config APM_ALLOW_INTS
2584	bool "Allow interrupts during APM BIOS calls"
2585	help
2586	  Normally we disable external interrupts while we are making calls to
2587	  the APM BIOS as a measure to lessen the effects of a badly behaving
2588	  BIOS implementation.  The BIOS should reenable interrupts if it
2589	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2590	  many of the newer IBM Thinkpads.  If you experience hangs when you
2591	  suspend, try setting this to Y.  Otherwise, say N.
2592
2593endif # APM
2594
2595source "drivers/cpufreq/Kconfig"
2596
2597source "drivers/cpuidle/Kconfig"
2598
2599source "drivers/idle/Kconfig"
2600
2601endmenu
2602
2603
2604menu "Bus options (PCI etc.)"
2605
2606choice
2607	prompt "PCI access mode"
2608	depends on X86_32 && PCI
2609	default PCI_GOANY
2610	help
2611	  On PCI systems, the BIOS can be used to detect the PCI devices and
2612	  determine their configuration. However, some old PCI motherboards
2613	  have BIOS bugs and may crash if this is done. Also, some embedded
2614	  PCI-based systems don't have any BIOS at all. Linux can also try to
2615	  detect the PCI hardware directly without using the BIOS.
2616
2617	  With this option, you can specify how Linux should detect the
2618	  PCI devices. If you choose "BIOS", the BIOS will be used,
2619	  if you choose "Direct", the BIOS won't be used, and if you
2620	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2621	  If you choose "Any", the kernel will try MMCONFIG, then the
2622	  direct access method and falls back to the BIOS if that doesn't
2623	  work. If unsure, go with the default, which is "Any".
2624
2625config PCI_GOBIOS
2626	bool "BIOS"
2627
2628config PCI_GOMMCONFIG
2629	bool "MMConfig"
2630
2631config PCI_GODIRECT
2632	bool "Direct"
2633
2634config PCI_GOOLPC
2635	bool "OLPC XO-1"
2636	depends on OLPC
2637
2638config PCI_GOANY
2639	bool "Any"
2640
2641endchoice
2642
2643config PCI_BIOS
2644	def_bool y
2645	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2646
2647# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2648config PCI_DIRECT
2649	def_bool y
2650	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2651
2652config PCI_MMCONFIG
2653	bool "Support mmconfig PCI config space access" if X86_64
2654	default y
2655	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2656	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2657
2658config PCI_OLPC
2659	def_bool y
2660	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2661
2662config PCI_XEN
2663	def_bool y
2664	depends on PCI && XEN
2665
2666config MMCONF_FAM10H
2667	def_bool y
2668	depends on X86_64 && PCI_MMCONFIG && ACPI
2669
2670config PCI_CNB20LE_QUIRK
2671	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2672	depends on PCI
2673	help
2674	  Read the PCI windows out of the CNB20LE host bridge. This allows
2675	  PCI hotplug to work on systems with the CNB20LE chipset which do
2676	  not have ACPI.
2677
2678	  There's no public spec for this chipset, and this functionality
2679	  is known to be incomplete.
2680
2681	  You should say N unless you know you need this.
2682
2683config ISA_BUS
2684	bool "ISA bus support on modern systems" if EXPERT
2685	help
2686	  Expose ISA bus device drivers and options available for selection and
2687	  configuration. Enable this option if your target machine has an ISA
2688	  bus. ISA is an older system, displaced by PCI and newer bus
2689	  architectures -- if your target machine is modern, it probably does
2690	  not have an ISA bus.
2691
2692	  If unsure, say N.
2693
2694# x86_64 have no ISA slots, but can have ISA-style DMA.
2695config ISA_DMA_API
2696	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2697	default y
2698	help
2699	  Enables ISA-style DMA support for devices requiring such controllers.
2700	  If unsure, say Y.
2701
2702if X86_32
2703
2704config ISA
2705	bool "ISA support"
2706	help
2707	  Find out whether you have ISA slots on your motherboard.  ISA is the
2708	  name of a bus system, i.e. the way the CPU talks to the other stuff
2709	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2710	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2711	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2712
2713config SCx200
2714	tristate "NatSemi SCx200 support"
2715	help
2716	  This provides basic support for National Semiconductor's
2717	  (now AMD's) Geode processors.  The driver probes for the
2718	  PCI-IDs of several on-chip devices, so its a good dependency
2719	  for other scx200_* drivers.
2720
2721	  If compiled as a module, the driver is named scx200.
2722
2723config SCx200HR_TIMER
2724	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2725	depends on SCx200
2726	default y
2727	help
2728	  This driver provides a clocksource built upon the on-chip
2729	  27MHz high-resolution timer.  Its also a workaround for
2730	  NSC Geode SC-1100's buggy TSC, which loses time when the
2731	  processor goes idle (as is done by the scheduler).  The
2732	  other workaround is idle=poll boot option.
2733
2734config OLPC
2735	bool "One Laptop Per Child support"
2736	depends on !X86_PAE
2737	select GPIOLIB
2738	select OF
2739	select OF_PROMTREE
2740	select IRQ_DOMAIN
2741	select OLPC_EC
2742	help
2743	  Add support for detecting the unique features of the OLPC
2744	  XO hardware.
2745
2746config OLPC_XO1_PM
2747	bool "OLPC XO-1 Power Management"
2748	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2749	help
2750	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2751
2752config OLPC_XO1_RTC
2753	bool "OLPC XO-1 Real Time Clock"
2754	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2755	help
2756	  Add support for the XO-1 real time clock, which can be used as a
2757	  programmable wakeup source.
2758
2759config OLPC_XO1_SCI
2760	bool "OLPC XO-1 SCI extras"
2761	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2762	depends on INPUT=y
2763	select POWER_SUPPLY
2764	help
2765	  Add support for SCI-based features of the OLPC XO-1 laptop:
2766	   - EC-driven system wakeups
2767	   - Power button
2768	   - Ebook switch
2769	   - Lid switch
2770	   - AC adapter status updates
2771	   - Battery status updates
2772
2773config OLPC_XO15_SCI
2774	bool "OLPC XO-1.5 SCI extras"
2775	depends on OLPC && ACPI
2776	select POWER_SUPPLY
2777	help
2778	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2779	   - EC-driven system wakeups
2780	   - AC adapter status updates
2781	   - Battery status updates
2782
2783config ALIX
2784	bool "PCEngines ALIX System Support (LED setup)"
2785	select GPIOLIB
2786	help
2787	  This option enables system support for the PCEngines ALIX.
2788	  At present this just sets up LEDs for GPIO control on
2789	  ALIX2/3/6 boards.  However, other system specific setup should
2790	  get added here.
2791
2792	  Note: You must still enable the drivers for GPIO and LED support
2793	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2794
2795	  Note: You have to set alix.force=1 for boards with Award BIOS.
2796
2797config NET5501
2798	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2799	select GPIOLIB
2800	help
2801	  This option enables system support for the Soekris Engineering net5501.
2802
2803config GEOS
2804	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2805	select GPIOLIB
2806	depends on DMI
2807	help
2808	  This option enables system support for the Traverse Technologies GEOS.
2809
2810config TS5500
2811	bool "Technologic Systems TS-5500 platform support"
2812	depends on MELAN
2813	select CHECK_SIGNATURE
2814	select NEW_LEDS
2815	select LEDS_CLASS
2816	help
2817	  This option enables system support for the Technologic Systems TS-5500.
2818
2819endif # X86_32
2820
2821config AMD_NB
2822	def_bool y
2823	depends on CPU_SUP_AMD && PCI
2824
2825endmenu
2826
2827
2828menu "Binary Emulations"
2829
2830config IA32_EMULATION
2831	bool "IA32 Emulation"
2832	depends on X86_64
2833	select ARCH_WANT_OLD_COMPAT_IPC
2834	select BINFMT_ELF
2835	select COMPAT_OLD_SIGACTION
2836	help
2837	  Include code to run legacy 32-bit programs under a
2838	  64-bit kernel. You should likely turn this on, unless you're
2839	  100% sure that you don't have any 32-bit programs left.
2840
2841config IA32_AOUT
2842	tristate "IA32 a.out support"
2843	depends on IA32_EMULATION
2844	depends on BROKEN
2845	help
2846	  Support old a.out binaries in the 32bit emulation.
2847
2848config X86_X32_ABI
2849	bool "x32 ABI for 64-bit mode"
2850	depends on X86_64
2851	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2852	# compressed debug sections to x86_x32 properly:
2853	# https://github.com/ClangBuiltLinux/linux/issues/514
2854	# https://github.com/ClangBuiltLinux/linux/issues/1141
2855	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2856	help
2857	  Include code to run binaries for the x32 native 32-bit ABI
2858	  for 64-bit processors.  An x32 process gets access to the
2859	  full 64-bit register file and wide data path while leaving
2860	  pointers at 32 bits for smaller memory footprint.
2861
2862config COMPAT_32
2863	def_bool y
2864	depends on IA32_EMULATION || X86_32
2865	select HAVE_UID16
2866	select OLD_SIGSUSPEND3
2867
2868config COMPAT
2869	def_bool y
2870	depends on IA32_EMULATION || X86_X32_ABI
2871
2872if COMPAT
2873config COMPAT_FOR_U64_ALIGNMENT
2874	def_bool y
2875
2876config SYSVIPC_COMPAT
2877	def_bool y
2878	depends on SYSVIPC
2879endif
2880
2881endmenu
2882
2883
2884config HAVE_ATOMIC_IOMAP
2885	def_bool y
2886	depends on X86_32
2887
2888source "arch/x86/kvm/Kconfig"
2889
2890source "arch/x86/Kconfig.assembler"
2891