xref: /openbmc/linux/arch/x86/Kconfig (revision 2dd6532e)
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_FORTIFY_SOURCE
80	select ARCH_HAS_GCOV_PROFILE_ALL
81	select ARCH_HAS_KCOV			if X86_64
82	select ARCH_HAS_MEM_ENCRYPT
83	select ARCH_HAS_MEMBARRIER_SYNC_CORE
84	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85	select ARCH_HAS_PMEM_API		if X86_64
86	select ARCH_HAS_PTE_DEVMAP		if X86_64
87	select ARCH_HAS_PTE_SPECIAL
88	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
89	select ARCH_HAS_COPY_MC			if X86_64
90	select ARCH_HAS_SET_MEMORY
91	select ARCH_HAS_SET_DIRECT_MAP
92	select ARCH_HAS_STRICT_KERNEL_RWX
93	select ARCH_HAS_STRICT_MODULE_RWX
94	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95	select ARCH_HAS_SYSCALL_WRAPPER
96	select ARCH_HAS_UBSAN_SANITIZE_ALL
97	select ARCH_HAS_VM_GET_PAGE_PROT
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_HUGETLB_PAGE_OPTIMIZE_VMEMMAP	if X86_64
125	select ARCH_WANT_LD_ORPHAN_WARN
126	select ARCH_WANTS_THP_SWAP		if X86_64
127	select ARCH_HAS_PARANOID_L1D_FLUSH
128	select BUILDTIME_TABLE_SORT
129	select CLKEVT_I8253
130	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
131	select CLOCKSOURCE_WATCHDOG
132	select DCACHE_WORD_ACCESS
133	select DYNAMIC_SIGFRAME
134	select EDAC_ATOMIC_SCRUB
135	select EDAC_SUPPORT
136	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
137	select GENERIC_CLOCKEVENTS_MIN_ADJUST
138	select GENERIC_CMOS_UPDATE
139	select GENERIC_CPU_AUTOPROBE
140	select GENERIC_CPU_VULNERABILITIES
141	select GENERIC_EARLY_IOREMAP
142	select GENERIC_ENTRY
143	select GENERIC_IOMAP
144	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
145	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
146	select GENERIC_IRQ_MIGRATION		if SMP
147	select GENERIC_IRQ_PROBE
148	select GENERIC_IRQ_RESERVATION_MODE
149	select GENERIC_IRQ_SHOW
150	select GENERIC_PENDING_IRQ		if SMP
151	select GENERIC_PTDUMP
152	select GENERIC_SMP_IDLE_THREAD
153	select GENERIC_TIME_VSYSCALL
154	select GENERIC_GETTIMEOFDAY
155	select GENERIC_VDSO_TIME_NS
156	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
157	select HARDIRQS_SW_RESEND
158	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
159	select HAVE_ACPI_APEI			if ACPI
160	select HAVE_ACPI_APEI_NMI		if ACPI
161	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
162	select HAVE_ARCH_AUDITSYSCALL
163	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
164	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
165	select HAVE_ARCH_JUMP_LABEL
166	select HAVE_ARCH_JUMP_LABEL_RELATIVE
167	select HAVE_ARCH_KASAN			if X86_64
168	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
169	select HAVE_ARCH_KFENCE
170	select HAVE_ARCH_KGDB
171	select HAVE_ARCH_MMAP_RND_BITS		if MMU
172	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
173	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
174	select HAVE_ARCH_PREL32_RELOCATIONS
175	select HAVE_ARCH_SECCOMP_FILTER
176	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
177	select HAVE_ARCH_STACKLEAK
178	select HAVE_ARCH_TRACEHOOK
179	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
180	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
181	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
182	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
183	select HAVE_ARCH_VMAP_STACK		if X86_64
184	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
185	select HAVE_ARCH_WITHIN_STACK_FRAMES
186	select HAVE_ASM_MODVERSIONS
187	select HAVE_CMPXCHG_DOUBLE
188	select HAVE_CMPXCHG_LOCAL
189	select HAVE_CONTEXT_TRACKING		if X86_64
190	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
191	select HAVE_C_RECORDMCOUNT
192	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
193	select HAVE_BUILDTIME_MCOUNT_SORT
194	select HAVE_DEBUG_KMEMLEAK
195	select HAVE_DMA_CONTIGUOUS
196	select HAVE_DYNAMIC_FTRACE
197	select HAVE_DYNAMIC_FTRACE_WITH_REGS
198	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
199	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
200	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
201	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
202	select HAVE_EBPF_JIT
203	select HAVE_EFFICIENT_UNALIGNED_ACCESS
204	select HAVE_EISA
205	select HAVE_EXIT_THREAD
206	select HAVE_FAST_GUP
207	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
208	select HAVE_FTRACE_MCOUNT_RECORD
209	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
210	select HAVE_FUNCTION_TRACER
211	select HAVE_GCC_PLUGINS
212	select HAVE_HW_BREAKPOINT
213	select HAVE_IOREMAP_PROT
214	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
215	select HAVE_IRQ_TIME_ACCOUNTING
216	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
217	select HAVE_KERNEL_BZIP2
218	select HAVE_KERNEL_GZIP
219	select HAVE_KERNEL_LZ4
220	select HAVE_KERNEL_LZMA
221	select HAVE_KERNEL_LZO
222	select HAVE_KERNEL_XZ
223	select HAVE_KERNEL_ZSTD
224	select HAVE_KPROBES
225	select HAVE_KPROBES_ON_FTRACE
226	select HAVE_FUNCTION_ERROR_INJECTION
227	select HAVE_KRETPROBES
228	select HAVE_RETHOOK
229	select HAVE_KVM
230	select HAVE_LIVEPATCH			if X86_64
231	select HAVE_MIXED_BREAKPOINTS_REGS
232	select HAVE_MOD_ARCH_SPECIFIC
233	select HAVE_MOVE_PMD
234	select HAVE_MOVE_PUD
235	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
236	select HAVE_NMI
237	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
238	select HAVE_OBJTOOL			if X86_64
239	select HAVE_OPTPROBES
240	select HAVE_PCSPKR_PLATFORM
241	select HAVE_PERF_EVENTS
242	select HAVE_PERF_EVENTS_NMI
243	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
244	select HAVE_PCI
245	select HAVE_PERF_REGS
246	select HAVE_PERF_USER_STACK_DUMP
247	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
248	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
249	select HAVE_REGS_AND_STACK_ACCESS_API
250	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
251	select HAVE_FUNCTION_ARG_ACCESS_API
252	select HAVE_SETUP_PER_CPU_AREA
253	select HAVE_SOFTIRQ_ON_OWN_STACK
254	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
255	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
256	select HAVE_STATIC_CALL
257	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
258	select HAVE_PREEMPT_DYNAMIC_CALL
259	select HAVE_RSEQ
260	select HAVE_SYSCALL_TRACEPOINTS
261	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
262	select HAVE_UNSTABLE_SCHED_CLOCK
263	select HAVE_USER_RETURN_NOTIFIER
264	select HAVE_GENERIC_VDSO
265	select HOTPLUG_SMT			if SMP
266	select IRQ_FORCED_THREADING
267	select NEED_PER_CPU_EMBED_FIRST_CHUNK
268	select NEED_PER_CPU_PAGE_FIRST_CHUNK
269	select NEED_SG_DMA_LENGTH
270	select PCI_DOMAINS			if PCI
271	select PCI_LOCKLESS_CONFIG		if PCI
272	select PERF_EVENTS
273	select RTC_LIB
274	select RTC_MC146818_LIB
275	select SPARSE_IRQ
276	select SRCU
277	select SYSCTL_EXCEPTION_TRACE
278	select THREAD_INFO_IN_TASK
279	select TRACE_IRQFLAGS_SUPPORT
280	select USER_STACKTRACE_SUPPORT
281	select VIRT_TO_BUS
282	select HAVE_ARCH_KCSAN			if X86_64
283	select X86_FEATURE_NAMES		if PROC_FS
284	select PROC_PID_ARCH_STATUS		if PROC_FS
285	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
286	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
287
288config INSTRUCTION_DECODER
289	def_bool y
290	depends on KPROBES || PERF_EVENTS || UPROBES
291
292config OUTPUT_FORMAT
293	string
294	default "elf32-i386" if X86_32
295	default "elf64-x86-64" if X86_64
296
297config LOCKDEP_SUPPORT
298	def_bool y
299
300config STACKTRACE_SUPPORT
301	def_bool y
302
303config MMU
304	def_bool y
305
306config ARCH_MMAP_RND_BITS_MIN
307	default 28 if 64BIT
308	default 8
309
310config ARCH_MMAP_RND_BITS_MAX
311	default 32 if 64BIT
312	default 16
313
314config ARCH_MMAP_RND_COMPAT_BITS_MIN
315	default 8
316
317config ARCH_MMAP_RND_COMPAT_BITS_MAX
318	default 16
319
320config SBUS
321	bool
322
323config GENERIC_ISA_DMA
324	def_bool y
325	depends on ISA_DMA_API
326
327config GENERIC_BUG
328	def_bool y
329	depends on BUG
330	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
331
332config GENERIC_BUG_RELATIVE_POINTERS
333	bool
334
335config ARCH_MAY_HAVE_PC_FDC
336	def_bool y
337	depends on ISA_DMA_API
338
339config GENERIC_CALIBRATE_DELAY
340	def_bool y
341
342config ARCH_HAS_CPU_RELAX
343	def_bool y
344
345config ARCH_HIBERNATION_POSSIBLE
346	def_bool y
347
348config ARCH_NR_GPIO
349	int
350	default 1024 if X86_64
351	default 512
352
353config ARCH_SUSPEND_POSSIBLE
354	def_bool y
355
356config AUDIT_ARCH
357	def_bool y if X86_64
358
359config KASAN_SHADOW_OFFSET
360	hex
361	depends on KASAN
362	default 0xdffffc0000000000
363
364config HAVE_INTEL_TXT
365	def_bool y
366	depends on INTEL_IOMMU && ACPI
367
368config X86_32_SMP
369	def_bool y
370	depends on X86_32 && SMP
371
372config X86_64_SMP
373	def_bool y
374	depends on X86_64 && SMP
375
376config ARCH_SUPPORTS_UPROBES
377	def_bool y
378
379config FIX_EARLYCON_MEM
380	def_bool y
381
382config DYNAMIC_PHYSICAL_MASK
383	bool
384
385config PGTABLE_LEVELS
386	int
387	default 5 if X86_5LEVEL
388	default 4 if X86_64
389	default 3 if X86_PAE
390	default 2
391
392config CC_HAS_SANE_STACKPROTECTOR
393	bool
394	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
395	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
396	help
397	  We have to make sure stack protector is unconditionally disabled if
398	  the compiler produces broken code or if it does not let us control
399	  the segment on 32-bit kernels.
400
401menu "Processor type and features"
402
403config SMP
404	bool "Symmetric multi-processing support"
405	help
406	  This enables support for systems with more than one CPU. If you have
407	  a system with only one CPU, say N. If you have a system with more
408	  than one CPU, say Y.
409
410	  If you say N here, the kernel will run on uni- and multiprocessor
411	  machines, but will use only one CPU of a multiprocessor machine. If
412	  you say Y here, the kernel will run on many, but not all,
413	  uniprocessor machines. On a uniprocessor machine, the kernel
414	  will run faster if you say N here.
415
416	  Note that if you say Y here and choose architecture "586" or
417	  "Pentium" under "Processor family", the kernel will not work on 486
418	  architectures. Similarly, multiprocessor kernels for the "PPro"
419	  architecture may not work on all Pentium based boards.
420
421	  People using multiprocessor machines who say Y here should also say
422	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
423	  Management" code will be disabled if you say Y here.
424
425	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
426	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
427	  <http://www.tldp.org/docs.html#howto>.
428
429	  If you don't know what to do here, say N.
430
431config X86_FEATURE_NAMES
432	bool "Processor feature human-readable names" if EMBEDDED
433	default y
434	help
435	  This option compiles in a table of x86 feature bits and corresponding
436	  names.  This is required to support /proc/cpuinfo and a few kernel
437	  messages.  You can disable this to save space, at the expense of
438	  making those few kernel messages show numeric feature bits instead.
439
440	  If in doubt, say Y.
441
442config X86_X2APIC
443	bool "Support x2apic"
444	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
445	help
446	  This enables x2apic support on CPUs that have this feature.
447
448	  This allows 32-bit apic IDs (so it can support very large systems),
449	  and accesses the local apic via MSRs not via mmio.
450
451	  If you don't know what to do here, say N.
452
453config X86_MPPARSE
454	bool "Enable MPS table" if ACPI
455	default y
456	depends on X86_LOCAL_APIC
457	help
458	  For old smp systems that do not have proper acpi support. Newer systems
459	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
460
461config GOLDFISH
462	def_bool y
463	depends on X86_GOLDFISH
464
465config RETPOLINE
466	bool "Avoid speculative indirect branches in kernel"
467	select OBJTOOL if HAVE_OBJTOOL
468	default y
469	help
470	  Compile kernel with the retpoline compiler options to guard against
471	  kernel-to-user data leaks by avoiding speculative indirect
472	  branches. Requires a compiler with -mindirect-branch=thunk-extern
473	  support for full protection. The kernel may run slower.
474
475config CC_HAS_SLS
476	def_bool $(cc-option,-mharden-sls=all)
477
478config SLS
479	bool "Mitigate Straight-Line-Speculation"
480	depends on CC_HAS_SLS && X86_64
481	select OBJTOOL if HAVE_OBJTOOL
482	default n
483	help
484	  Compile the kernel with straight-line-speculation options to guard
485	  against straight line speculation. The kernel image might be slightly
486	  larger.
487
488config X86_CPU_RESCTRL
489	bool "x86 CPU resource control support"
490	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
491	select KERNFS
492	select PROC_CPU_RESCTRL		if PROC_FS
493	help
494	  Enable x86 CPU resource control support.
495
496	  Provide support for the allocation and monitoring of system resources
497	  usage by the CPU.
498
499	  Intel calls this Intel Resource Director Technology
500	  (Intel(R) RDT). More information about RDT can be found in the
501	  Intel x86 Architecture Software Developer Manual.
502
503	  AMD calls this AMD Platform Quality of Service (AMD QoS).
504	  More information about AMD QoS can be found in the AMD64 Technology
505	  Platform Quality of Service Extensions manual.
506
507	  Say N if unsure.
508
509if X86_32
510config X86_BIGSMP
511	bool "Support for big SMP systems with more than 8 CPUs"
512	depends on SMP
513	help
514	  This option is needed for the systems that have more than 8 CPUs.
515
516config X86_EXTENDED_PLATFORM
517	bool "Support for extended (non-PC) x86 platforms"
518	default y
519	help
520	  If you disable this option then the kernel will only support
521	  standard PC platforms. (which covers the vast majority of
522	  systems out there.)
523
524	  If you enable this option then you'll be able to select support
525	  for the following (non-PC) 32 bit x86 platforms:
526		Goldfish (Android emulator)
527		AMD Elan
528		RDC R-321x SoC
529		SGI 320/540 (Visual Workstation)
530		STA2X11-based (e.g. Northville)
531		Moorestown MID devices
532
533	  If you have one of these systems, or if you want to build a
534	  generic distribution kernel, say Y here - otherwise say N.
535endif # X86_32
536
537if X86_64
538config X86_EXTENDED_PLATFORM
539	bool "Support for extended (non-PC) x86 platforms"
540	default y
541	help
542	  If you disable this option then the kernel will only support
543	  standard PC platforms. (which covers the vast majority of
544	  systems out there.)
545
546	  If you enable this option then you'll be able to select support
547	  for the following (non-PC) 64 bit x86 platforms:
548		Numascale NumaChip
549		ScaleMP vSMP
550		SGI Ultraviolet
551
552	  If you have one of these systems, or if you want to build a
553	  generic distribution kernel, say Y here - otherwise say N.
554endif # X86_64
555# This is an alphabetically sorted list of 64 bit extended platforms
556# Please maintain the alphabetic order if and when there are additions
557config X86_NUMACHIP
558	bool "Numascale NumaChip"
559	depends on X86_64
560	depends on X86_EXTENDED_PLATFORM
561	depends on NUMA
562	depends on SMP
563	depends on X86_X2APIC
564	depends on PCI_MMCONFIG
565	help
566	  Adds support for Numascale NumaChip large-SMP systems. Needed to
567	  enable more than ~168 cores.
568	  If you don't have one of these, you should say N here.
569
570config X86_VSMP
571	bool "ScaleMP vSMP"
572	select HYPERVISOR_GUEST
573	select PARAVIRT
574	depends on X86_64 && PCI
575	depends on X86_EXTENDED_PLATFORM
576	depends on SMP
577	help
578	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
579	  supposed to run on these EM64T-based machines.  Only choose this option
580	  if you have one of these machines.
581
582config X86_UV
583	bool "SGI Ultraviolet"
584	depends on X86_64
585	depends on X86_EXTENDED_PLATFORM
586	depends on NUMA
587	depends on EFI
588	depends on KEXEC_CORE
589	depends on X86_X2APIC
590	depends on PCI
591	help
592	  This option is needed in order to support SGI Ultraviolet systems.
593	  If you don't have one of these, you should say N here.
594
595# Following is an alphabetically sorted list of 32 bit extended platforms
596# Please maintain the alphabetic order if and when there are additions
597
598config X86_GOLDFISH
599	bool "Goldfish (Virtual Platform)"
600	depends on X86_EXTENDED_PLATFORM
601	help
602	  Enable support for the Goldfish virtual platform used primarily
603	  for Android development. Unless you are building for the Android
604	  Goldfish emulator say N here.
605
606config X86_INTEL_CE
607	bool "CE4100 TV platform"
608	depends on PCI
609	depends on PCI_GODIRECT
610	depends on X86_IO_APIC
611	depends on X86_32
612	depends on X86_EXTENDED_PLATFORM
613	select X86_REBOOTFIXUPS
614	select OF
615	select OF_EARLY_FLATTREE
616	help
617	  Select for the Intel CE media processor (CE4100) SOC.
618	  This option compiles in support for the CE4100 SOC for settop
619	  boxes and media devices.
620
621config X86_INTEL_MID
622	bool "Intel MID platform support"
623	depends on X86_EXTENDED_PLATFORM
624	depends on X86_PLATFORM_DEVICES
625	depends on PCI
626	depends on X86_64 || (PCI_GOANY && X86_32)
627	depends on X86_IO_APIC
628	select I2C
629	select DW_APB_TIMER
630	select INTEL_SCU_PCI
631	help
632	  Select to build a kernel capable of supporting Intel MID (Mobile
633	  Internet Device) platform systems which do not have the PCI legacy
634	  interfaces. If you are building for a PC class system say N here.
635
636	  Intel MID platforms are based on an Intel processor and chipset which
637	  consume less power than most of the x86 derivatives.
638
639config X86_INTEL_QUARK
640	bool "Intel Quark platform support"
641	depends on X86_32
642	depends on X86_EXTENDED_PLATFORM
643	depends on X86_PLATFORM_DEVICES
644	depends on X86_TSC
645	depends on PCI
646	depends on PCI_GOANY
647	depends on X86_IO_APIC
648	select IOSF_MBI
649	select INTEL_IMR
650	select COMMON_CLK
651	help
652	  Select to include support for Quark X1000 SoC.
653	  Say Y here if you have a Quark based system such as the Arduino
654	  compatible Intel Galileo.
655
656config X86_INTEL_LPSS
657	bool "Intel Low Power Subsystem Support"
658	depends on X86 && ACPI && PCI
659	select COMMON_CLK
660	select PINCTRL
661	select IOSF_MBI
662	help
663	  Select to build support for Intel Low Power Subsystem such as
664	  found on Intel Lynxpoint PCH. Selecting this option enables
665	  things like clock tree (common clock framework) and pincontrol
666	  which are needed by the LPSS peripheral drivers.
667
668config X86_AMD_PLATFORM_DEVICE
669	bool "AMD ACPI2Platform devices support"
670	depends on ACPI
671	select COMMON_CLK
672	select PINCTRL
673	help
674	  Select to interpret AMD specific ACPI device to platform device
675	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
676	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
677	  implemented under PINCTRL subsystem.
678
679config IOSF_MBI
680	tristate "Intel SoC IOSF Sideband support for SoC platforms"
681	depends on PCI
682	help
683	  This option enables sideband register access support for Intel SoC
684	  platforms. On these platforms the IOSF sideband is used in lieu of
685	  MSR's for some register accesses, mostly but not limited to thermal
686	  and power. Drivers may query the availability of this device to
687	  determine if they need the sideband in order to work on these
688	  platforms. The sideband is available on the following SoC products.
689	  This list is not meant to be exclusive.
690	   - BayTrail
691	   - Braswell
692	   - Quark
693
694	  You should say Y if you are running a kernel on one of these SoC's.
695
696config IOSF_MBI_DEBUG
697	bool "Enable IOSF sideband access through debugfs"
698	depends on IOSF_MBI && DEBUG_FS
699	help
700	  Select this option to expose the IOSF sideband access registers (MCR,
701	  MDR, MCRX) through debugfs to write and read register information from
702	  different units on the SoC. This is most useful for obtaining device
703	  state information for debug and analysis. As this is a general access
704	  mechanism, users of this option would have specific knowledge of the
705	  device they want to access.
706
707	  If you don't require the option or are in doubt, say N.
708
709config X86_RDC321X
710	bool "RDC R-321x SoC"
711	depends on X86_32
712	depends on X86_EXTENDED_PLATFORM
713	select M486
714	select X86_REBOOTFIXUPS
715	help
716	  This option is needed for RDC R-321x system-on-chip, also known
717	  as R-8610-(G).
718	  If you don't have one of these chips, you should say N here.
719
720config X86_32_NON_STANDARD
721	bool "Support non-standard 32-bit SMP architectures"
722	depends on X86_32 && SMP
723	depends on X86_EXTENDED_PLATFORM
724	help
725	  This option compiles in the bigsmp and STA2X11 default
726	  subarchitectures.  It is intended for a generic binary
727	  kernel. If you select them all, kernel will probe it one by
728	  one and will fallback to default.
729
730# Alphabetically sorted list of Non standard 32 bit platforms
731
732config X86_SUPPORTS_MEMORY_FAILURE
733	def_bool y
734	# MCE code calls memory_failure():
735	depends on X86_MCE
736	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
737	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
738	depends on X86_64 || !SPARSEMEM
739	select ARCH_SUPPORTS_MEMORY_FAILURE
740
741config STA2X11
742	bool "STA2X11 Companion Chip Support"
743	depends on X86_32_NON_STANDARD && PCI
744	select SWIOTLB
745	select MFD_STA2X11
746	select GPIOLIB
747	help
748	  This adds support for boards based on the STA2X11 IO-Hub,
749	  a.k.a. "ConneXt". The chip is used in place of the standard
750	  PC chipset, so all "standard" peripherals are missing. If this
751	  option is selected the kernel will still be able to boot on
752	  standard PC machines.
753
754config X86_32_IRIS
755	tristate "Eurobraille/Iris poweroff module"
756	depends on X86_32
757	help
758	  The Iris machines from EuroBraille do not have APM or ACPI support
759	  to shut themselves down properly.  A special I/O sequence is
760	  needed to do so, which is what this module does at
761	  kernel shutdown.
762
763	  This is only for Iris machines from EuroBraille.
764
765	  If unused, say N.
766
767config SCHED_OMIT_FRAME_POINTER
768	def_bool y
769	prompt "Single-depth WCHAN output"
770	depends on X86
771	help
772	  Calculate simpler /proc/<PID>/wchan values. If this option
773	  is disabled then wchan values will recurse back to the
774	  caller function. This provides more accurate wchan values,
775	  at the expense of slightly more scheduling overhead.
776
777	  If in doubt, say "Y".
778
779menuconfig HYPERVISOR_GUEST
780	bool "Linux guest support"
781	help
782	  Say Y here to enable options for running Linux under various hyper-
783	  visors. This option enables basic hypervisor detection and platform
784	  setup.
785
786	  If you say N, all options in this submenu will be skipped and
787	  disabled, and Linux guest support won't be built in.
788
789if HYPERVISOR_GUEST
790
791config PARAVIRT
792	bool "Enable paravirtualization code"
793	depends on HAVE_STATIC_CALL
794	help
795	  This changes the kernel so it can modify itself when it is run
796	  under a hypervisor, potentially improving performance significantly
797	  over full virtualization.  However, when run without a hypervisor
798	  the kernel is theoretically slower and slightly larger.
799
800config PARAVIRT_XXL
801	bool
802
803config PARAVIRT_DEBUG
804	bool "paravirt-ops debugging"
805	depends on PARAVIRT && DEBUG_KERNEL
806	help
807	  Enable to debug paravirt_ops internals.  Specifically, BUG if
808	  a paravirt_op is missing when it is called.
809
810config PARAVIRT_SPINLOCKS
811	bool "Paravirtualization layer for spinlocks"
812	depends on PARAVIRT && SMP
813	help
814	  Paravirtualized spinlocks allow a pvops backend to replace the
815	  spinlock implementation with something virtualization-friendly
816	  (for example, block the virtual CPU rather than spinning).
817
818	  It has a minimal impact on native kernels and gives a nice performance
819	  benefit on paravirtualized KVM / Xen kernels.
820
821	  If you are unsure how to answer this question, answer Y.
822
823config X86_HV_CALLBACK_VECTOR
824	def_bool n
825
826source "arch/x86/xen/Kconfig"
827
828config KVM_GUEST
829	bool "KVM Guest support (including kvmclock)"
830	depends on PARAVIRT
831	select PARAVIRT_CLOCK
832	select ARCH_CPUIDLE_HALTPOLL
833	select X86_HV_CALLBACK_VECTOR
834	default y
835	help
836	  This option enables various optimizations for running under the KVM
837	  hypervisor. It includes a paravirtualized clock, so that instead
838	  of relying on a PIT (or probably other) emulation by the
839	  underlying device model, the host provides the guest with
840	  timing infrastructure such as time of day, and system time
841
842config ARCH_CPUIDLE_HALTPOLL
843	def_bool n
844	prompt "Disable host haltpoll when loading haltpoll driver"
845	help
846	  If virtualized under KVM, disable host haltpoll.
847
848config PVH
849	bool "Support for running PVH guests"
850	help
851	  This option enables the PVH entry point for guest virtual machines
852	  as specified in the x86/HVM direct boot ABI.
853
854config PARAVIRT_TIME_ACCOUNTING
855	bool "Paravirtual steal time accounting"
856	depends on PARAVIRT
857	help
858	  Select this option to enable fine granularity task steal time
859	  accounting. Time spent executing other tasks in parallel with
860	  the current vCPU is discounted from the vCPU power. To account for
861	  that, there can be a small performance impact.
862
863	  If in doubt, say N here.
864
865config PARAVIRT_CLOCK
866	bool
867
868config JAILHOUSE_GUEST
869	bool "Jailhouse non-root cell support"
870	depends on X86_64 && PCI
871	select X86_PM_TIMER
872	help
873	  This option allows to run Linux as guest in a Jailhouse non-root
874	  cell. You can leave this option disabled if you only want to start
875	  Jailhouse and run Linux afterwards in the root cell.
876
877config ACRN_GUEST
878	bool "ACRN Guest support"
879	depends on X86_64
880	select X86_HV_CALLBACK_VECTOR
881	help
882	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
883	  a flexible, lightweight reference open-source hypervisor, built with
884	  real-time and safety-criticality in mind. It is built for embedded
885	  IOT with small footprint and real-time features. More details can be
886	  found in https://projectacrn.org/.
887
888config INTEL_TDX_GUEST
889	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
890	depends on X86_64 && CPU_SUP_INTEL
891	depends on X86_X2APIC
892	select ARCH_HAS_CC_PLATFORM
893	select X86_MEM_ENCRYPT
894	select X86_MCE
895	help
896	  Support running as a guest under Intel TDX.  Without this support,
897	  the guest kernel can not boot or run under TDX.
898	  TDX includes memory encryption and integrity capabilities
899	  which protect the confidentiality and integrity of guest
900	  memory contents and CPU state. TDX guests are protected from
901	  some attacks from the VMM.
902
903endif # HYPERVISOR_GUEST
904
905source "arch/x86/Kconfig.cpu"
906
907config HPET_TIMER
908	def_bool X86_64
909	prompt "HPET Timer Support" if X86_32
910	help
911	  Use the IA-PC HPET (High Precision Event Timer) to manage
912	  time in preference to the PIT and RTC, if a HPET is
913	  present.
914	  HPET is the next generation timer replacing legacy 8254s.
915	  The HPET provides a stable time base on SMP
916	  systems, unlike the TSC, but it is more expensive to access,
917	  as it is off-chip.  The interface used is documented
918	  in the HPET spec, revision 1.
919
920	  You can safely choose Y here.  However, HPET will only be
921	  activated if the platform and the BIOS support this feature.
922	  Otherwise the 8254 will be used for timing services.
923
924	  Choose N to continue using the legacy 8254 timer.
925
926config HPET_EMULATE_RTC
927	def_bool y
928	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
929
930# Mark as expert because too many people got it wrong.
931# The code disables itself when not needed.
932config DMI
933	default y
934	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
935	bool "Enable DMI scanning" if EXPERT
936	help
937	  Enabled scanning of DMI to identify machine quirks. Say Y
938	  here unless you have verified that your setup is not
939	  affected by entries in the DMI blacklist. Required by PNP
940	  BIOS code.
941
942config GART_IOMMU
943	bool "Old AMD GART IOMMU support"
944	select DMA_OPS
945	select IOMMU_HELPER
946	select SWIOTLB
947	depends on X86_64 && PCI && AMD_NB
948	help
949	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
950	  GART based hardware IOMMUs.
951
952	  The GART supports full DMA access for devices with 32-bit access
953	  limitations, on systems with more than 3 GB. This is usually needed
954	  for USB, sound, many IDE/SATA chipsets and some other devices.
955
956	  Newer systems typically have a modern AMD IOMMU, supported via
957	  the CONFIG_AMD_IOMMU=y config option.
958
959	  In normal configurations this driver is only active when needed:
960	  there's more than 3 GB of memory and the system contains a
961	  32-bit limited device.
962
963	  If unsure, say Y.
964
965config BOOT_VESA_SUPPORT
966	bool
967	help
968	  If true, at least one selected framebuffer driver can take advantage
969	  of VESA video modes set at an early boot stage via the vga= parameter.
970
971config MAXSMP
972	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
973	depends on X86_64 && SMP && DEBUG_KERNEL
974	select CPUMASK_OFFSTACK
975	help
976	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
977	  If unsure, say N.
978
979#
980# The maximum number of CPUs supported:
981#
982# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
983# and which can be configured interactively in the
984# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
985#
986# The ranges are different on 32-bit and 64-bit kernels, depending on
987# hardware capabilities and scalability features of the kernel.
988#
989# ( If MAXSMP is enabled we just use the highest possible value and disable
990#   interactive configuration. )
991#
992
993config NR_CPUS_RANGE_BEGIN
994	int
995	default NR_CPUS_RANGE_END if MAXSMP
996	default    1 if !SMP
997	default    2
998
999config NR_CPUS_RANGE_END
1000	int
1001	depends on X86_32
1002	default   64 if  SMP &&  X86_BIGSMP
1003	default    8 if  SMP && !X86_BIGSMP
1004	default    1 if !SMP
1005
1006config NR_CPUS_RANGE_END
1007	int
1008	depends on X86_64
1009	default 8192 if  SMP && CPUMASK_OFFSTACK
1010	default  512 if  SMP && !CPUMASK_OFFSTACK
1011	default    1 if !SMP
1012
1013config NR_CPUS_DEFAULT
1014	int
1015	depends on X86_32
1016	default   32 if  X86_BIGSMP
1017	default    8 if  SMP
1018	default    1 if !SMP
1019
1020config NR_CPUS_DEFAULT
1021	int
1022	depends on X86_64
1023	default 8192 if  MAXSMP
1024	default   64 if  SMP
1025	default    1 if !SMP
1026
1027config NR_CPUS
1028	int "Maximum number of CPUs" if SMP && !MAXSMP
1029	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1030	default NR_CPUS_DEFAULT
1031	help
1032	  This allows you to specify the maximum number of CPUs which this
1033	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1034	  supported value is 8192, otherwise the maximum value is 512.  The
1035	  minimum value which makes sense is 2.
1036
1037	  This is purely to save memory: each supported CPU adds about 8KB
1038	  to the kernel image.
1039
1040config SCHED_CLUSTER
1041	bool "Cluster scheduler support"
1042	depends on SMP
1043	default y
1044	help
1045	  Cluster scheduler support improves the CPU scheduler's decision
1046	  making when dealing with machines that have clusters of CPUs.
1047	  Cluster usually means a couple of CPUs which are placed closely
1048	  by sharing mid-level caches, last-level cache tags or internal
1049	  busses.
1050
1051config SCHED_SMT
1052	def_bool y if SMP
1053
1054config SCHED_MC
1055	def_bool y
1056	prompt "Multi-core scheduler support"
1057	depends on SMP
1058	help
1059	  Multi-core scheduler support improves the CPU scheduler's decision
1060	  making when dealing with multi-core CPU chips at a cost of slightly
1061	  increased overhead in some places. If unsure say N here.
1062
1063config SCHED_MC_PRIO
1064	bool "CPU core priorities scheduler support"
1065	depends on SCHED_MC && CPU_SUP_INTEL
1066	select X86_INTEL_PSTATE
1067	select CPU_FREQ
1068	default y
1069	help
1070	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1071	  core ordering determined at manufacturing time, which allows
1072	  certain cores to reach higher turbo frequencies (when running
1073	  single threaded workloads) than others.
1074
1075	  Enabling this kernel feature teaches the scheduler about
1076	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1077	  scheduler's CPU selection logic accordingly, so that higher
1078	  overall system performance can be achieved.
1079
1080	  This feature will have no effect on CPUs without this feature.
1081
1082	  If unsure say Y here.
1083
1084config UP_LATE_INIT
1085	def_bool y
1086	depends on !SMP && X86_LOCAL_APIC
1087
1088config X86_UP_APIC
1089	bool "Local APIC support on uniprocessors" if !PCI_MSI
1090	default PCI_MSI
1091	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1092	help
1093	  A local APIC (Advanced Programmable Interrupt Controller) is an
1094	  integrated interrupt controller in the CPU. If you have a single-CPU
1095	  system which has a processor with a local APIC, you can say Y here to
1096	  enable and use it. If you say Y here even though your machine doesn't
1097	  have a local APIC, then the kernel will still run with no slowdown at
1098	  all. The local APIC supports CPU-generated self-interrupts (timer,
1099	  performance counters), and the NMI watchdog which detects hard
1100	  lockups.
1101
1102config X86_UP_IOAPIC
1103	bool "IO-APIC support on uniprocessors"
1104	depends on X86_UP_APIC
1105	help
1106	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1107	  SMP-capable replacement for PC-style interrupt controllers. Most
1108	  SMP systems and many recent uniprocessor systems have one.
1109
1110	  If you have a single-CPU system with an IO-APIC, you can say Y here
1111	  to use it. If you say Y here even though your machine doesn't have
1112	  an IO-APIC, then the kernel will still run with no slowdown at all.
1113
1114config X86_LOCAL_APIC
1115	def_bool y
1116	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1117	select IRQ_DOMAIN_HIERARCHY
1118	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1119
1120config X86_IO_APIC
1121	def_bool y
1122	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1123
1124config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1125	bool "Reroute for broken boot IRQs"
1126	depends on X86_IO_APIC
1127	help
1128	  This option enables a workaround that fixes a source of
1129	  spurious interrupts. This is recommended when threaded
1130	  interrupt handling is used on systems where the generation of
1131	  superfluous "boot interrupts" cannot be disabled.
1132
1133	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1134	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1135	  kernel does during interrupt handling). On chipsets where this
1136	  boot IRQ generation cannot be disabled, this workaround keeps
1137	  the original IRQ line masked so that only the equivalent "boot
1138	  IRQ" is delivered to the CPUs. The workaround also tells the
1139	  kernel to set up the IRQ handler on the boot IRQ line. In this
1140	  way only one interrupt is delivered to the kernel. Otherwise
1141	  the spurious second interrupt may cause the kernel to bring
1142	  down (vital) interrupt lines.
1143
1144	  Only affects "broken" chipsets. Interrupt sharing may be
1145	  increased on these systems.
1146
1147config X86_MCE
1148	bool "Machine Check / overheating reporting"
1149	select GENERIC_ALLOCATOR
1150	default y
1151	help
1152	  Machine Check support allows the processor to notify the
1153	  kernel if it detects a problem (e.g. overheating, data corruption).
1154	  The action the kernel takes depends on the severity of the problem,
1155	  ranging from warning messages to halting the machine.
1156
1157config X86_MCELOG_LEGACY
1158	bool "Support for deprecated /dev/mcelog character device"
1159	depends on X86_MCE
1160	help
1161	  Enable support for /dev/mcelog which is needed by the old mcelog
1162	  userspace logging daemon. Consider switching to the new generation
1163	  rasdaemon solution.
1164
1165config X86_MCE_INTEL
1166	def_bool y
1167	prompt "Intel MCE features"
1168	depends on X86_MCE && X86_LOCAL_APIC
1169	help
1170	  Additional support for intel specific MCE features such as
1171	  the thermal monitor.
1172
1173config X86_MCE_AMD
1174	def_bool y
1175	prompt "AMD MCE features"
1176	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1177	help
1178	  Additional support for AMD specific MCE features such as
1179	  the DRAM Error Threshold.
1180
1181config X86_ANCIENT_MCE
1182	bool "Support for old Pentium 5 / WinChip machine checks"
1183	depends on X86_32 && X86_MCE
1184	help
1185	  Include support for machine check handling on old Pentium 5 or WinChip
1186	  systems. These typically need to be enabled explicitly on the command
1187	  line.
1188
1189config X86_MCE_THRESHOLD
1190	depends on X86_MCE_AMD || X86_MCE_INTEL
1191	def_bool y
1192
1193config X86_MCE_INJECT
1194	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1195	tristate "Machine check injector support"
1196	help
1197	  Provide support for injecting machine checks for testing purposes.
1198	  If you don't know what a machine check is and you don't do kernel
1199	  QA it is safe to say n.
1200
1201source "arch/x86/events/Kconfig"
1202
1203config X86_LEGACY_VM86
1204	bool "Legacy VM86 support"
1205	depends on X86_32
1206	help
1207	  This option allows user programs to put the CPU into V8086
1208	  mode, which is an 80286-era approximation of 16-bit real mode.
1209
1210	  Some very old versions of X and/or vbetool require this option
1211	  for user mode setting.  Similarly, DOSEMU will use it if
1212	  available to accelerate real mode DOS programs.  However, any
1213	  recent version of DOSEMU, X, or vbetool should be fully
1214	  functional even without kernel VM86 support, as they will all
1215	  fall back to software emulation. Nevertheless, if you are using
1216	  a 16-bit DOS program where 16-bit performance matters, vm86
1217	  mode might be faster than emulation and you might want to
1218	  enable this option.
1219
1220	  Note that any app that works on a 64-bit kernel is unlikely to
1221	  need this option, as 64-bit kernels don't, and can't, support
1222	  V8086 mode. This option is also unrelated to 16-bit protected
1223	  mode and is not needed to run most 16-bit programs under Wine.
1224
1225	  Enabling this option increases the complexity of the kernel
1226	  and slows down exception handling a tiny bit.
1227
1228	  If unsure, say N here.
1229
1230config VM86
1231	bool
1232	default X86_LEGACY_VM86
1233
1234config X86_16BIT
1235	bool "Enable support for 16-bit segments" if EXPERT
1236	default y
1237	depends on MODIFY_LDT_SYSCALL
1238	help
1239	  This option is required by programs like Wine to run 16-bit
1240	  protected mode legacy code on x86 processors.  Disabling
1241	  this option saves about 300 bytes on i386, or around 6K text
1242	  plus 16K runtime memory on x86-64,
1243
1244config X86_ESPFIX32
1245	def_bool y
1246	depends on X86_16BIT && X86_32
1247
1248config X86_ESPFIX64
1249	def_bool y
1250	depends on X86_16BIT && X86_64
1251
1252config X86_VSYSCALL_EMULATION
1253	bool "Enable vsyscall emulation" if EXPERT
1254	default y
1255	depends on X86_64
1256	help
1257	  This enables emulation of the legacy vsyscall page.  Disabling
1258	  it is roughly equivalent to booting with vsyscall=none, except
1259	  that it will also disable the helpful warning if a program
1260	  tries to use a vsyscall.  With this option set to N, offending
1261	  programs will just segfault, citing addresses of the form
1262	  0xffffffffff600?00.
1263
1264	  This option is required by many programs built before 2013, and
1265	  care should be used even with newer programs if set to N.
1266
1267	  Disabling this option saves about 7K of kernel size and
1268	  possibly 4K of additional runtime pagetable memory.
1269
1270config X86_IOPL_IOPERM
1271	bool "IOPERM and IOPL Emulation"
1272	default y
1273	help
1274	  This enables the ioperm() and iopl() syscalls which are necessary
1275	  for legacy applications.
1276
1277	  Legacy IOPL support is an overbroad mechanism which allows user
1278	  space aside of accessing all 65536 I/O ports also to disable
1279	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1280	  capabilities and permission from potentially active security
1281	  modules.
1282
1283	  The emulation restricts the functionality of the syscall to
1284	  only allowing the full range I/O port access, but prevents the
1285	  ability to disable interrupts from user space which would be
1286	  granted if the hardware IOPL mechanism would be used.
1287
1288config TOSHIBA
1289	tristate "Toshiba Laptop support"
1290	depends on X86_32
1291	help
1292	  This adds a driver to safely access the System Management Mode of
1293	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1294	  not work on models with a Phoenix BIOS. The System Management Mode
1295	  is used to set the BIOS and power saving options on Toshiba portables.
1296
1297	  For information on utilities to make use of this driver see the
1298	  Toshiba Linux utilities web site at:
1299	  <http://www.buzzard.org.uk/toshiba/>.
1300
1301	  Say Y if you intend to run this kernel on a Toshiba portable.
1302	  Say N otherwise.
1303
1304config X86_REBOOTFIXUPS
1305	bool "Enable X86 board specific fixups for reboot"
1306	depends on X86_32
1307	help
1308	  This enables chipset and/or board specific fixups to be done
1309	  in order to get reboot to work correctly. This is only needed on
1310	  some combinations of hardware and BIOS. The symptom, for which
1311	  this config is intended, is when reboot ends with a stalled/hung
1312	  system.
1313
1314	  Currently, the only fixup is for the Geode machines using
1315	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1316
1317	  Say Y if you want to enable the fixup. Currently, it's safe to
1318	  enable this option even if you don't need it.
1319	  Say N otherwise.
1320
1321config MICROCODE
1322	bool "CPU microcode loading support"
1323	default y
1324	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1325	help
1326	  If you say Y here, you will be able to update the microcode on
1327	  Intel and AMD processors. The Intel support is for the IA32 family,
1328	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1329	  AMD support is for families 0x10 and later. You will obviously need
1330	  the actual microcode binary data itself which is not shipped with
1331	  the Linux kernel.
1332
1333	  The preferred method to load microcode from a detached initrd is described
1334	  in Documentation/x86/microcode.rst. For that you need to enable
1335	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1336	  initrd for microcode blobs.
1337
1338	  In addition, you can build the microcode into the kernel. For that you
1339	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1340	  config option.
1341
1342config MICROCODE_INTEL
1343	bool "Intel microcode loading support"
1344	depends on CPU_SUP_INTEL && MICROCODE
1345	default MICROCODE
1346	help
1347	  This options enables microcode patch loading support for Intel
1348	  processors.
1349
1350	  For the current Intel microcode data package go to
1351	  <https://downloadcenter.intel.com> and search for
1352	  'Linux Processor Microcode Data File'.
1353
1354config MICROCODE_AMD
1355	bool "AMD microcode loading support"
1356	depends on CPU_SUP_AMD && MICROCODE
1357	help
1358	  If you select this option, microcode patch loading support for AMD
1359	  processors will be enabled.
1360
1361config MICROCODE_LATE_LOADING
1362	bool "Late microcode loading (DANGEROUS)"
1363	default n
1364	depends on MICROCODE
1365	help
1366	  Loading microcode late, when the system is up and executing instructions
1367	  is a tricky business and should be avoided if possible. Just the sequence
1368	  of synchronizing all cores and SMT threads is one fragile dance which does
1369	  not guarantee that cores might not softlock after the loading. Therefore,
1370	  use this at your own risk. Late loading taints the kernel too.
1371
1372config X86_MSR
1373	tristate "/dev/cpu/*/msr - Model-specific register support"
1374	help
1375	  This device gives privileged processes access to the x86
1376	  Model-Specific Registers (MSRs).  It is a character device with
1377	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1378	  MSR accesses are directed to a specific CPU on multi-processor
1379	  systems.
1380
1381config X86_CPUID
1382	tristate "/dev/cpu/*/cpuid - CPU information support"
1383	help
1384	  This device gives processes access to the x86 CPUID instruction to
1385	  be executed on a specific processor.  It is a character device
1386	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1387	  /dev/cpu/31/cpuid.
1388
1389choice
1390	prompt "High Memory Support"
1391	default HIGHMEM4G
1392	depends on X86_32
1393
1394config NOHIGHMEM
1395	bool "off"
1396	help
1397	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1398	  However, the address space of 32-bit x86 processors is only 4
1399	  Gigabytes large. That means that, if you have a large amount of
1400	  physical memory, not all of it can be "permanently mapped" by the
1401	  kernel. The physical memory that's not permanently mapped is called
1402	  "high memory".
1403
1404	  If you are compiling a kernel which will never run on a machine with
1405	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1406	  choice and suitable for most users). This will result in a "3GB/1GB"
1407	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1408	  space and the remaining part of the 4GB virtual memory space is used
1409	  by the kernel to permanently map as much physical memory as
1410	  possible.
1411
1412	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1413	  answer "4GB" here.
1414
1415	  If more than 4 Gigabytes is used then answer "64GB" here. This
1416	  selection turns Intel PAE (Physical Address Extension) mode on.
1417	  PAE implements 3-level paging on IA32 processors. PAE is fully
1418	  supported by Linux, PAE mode is implemented on all recent Intel
1419	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1420	  then the kernel will not boot on CPUs that don't support PAE!
1421
1422	  The actual amount of total physical memory will either be
1423	  auto detected or can be forced by using a kernel command line option
1424	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1425	  your boot loader (lilo or loadlin) about how to pass options to the
1426	  kernel at boot time.)
1427
1428	  If unsure, say "off".
1429
1430config HIGHMEM4G
1431	bool "4GB"
1432	help
1433	  Select this if you have a 32-bit processor and between 1 and 4
1434	  gigabytes of physical RAM.
1435
1436config HIGHMEM64G
1437	bool "64GB"
1438	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1439	select X86_PAE
1440	help
1441	  Select this if you have a 32-bit processor and more than 4
1442	  gigabytes of physical RAM.
1443
1444endchoice
1445
1446choice
1447	prompt "Memory split" if EXPERT
1448	default VMSPLIT_3G
1449	depends on X86_32
1450	help
1451	  Select the desired split between kernel and user memory.
1452
1453	  If the address range available to the kernel is less than the
1454	  physical memory installed, the remaining memory will be available
1455	  as "high memory". Accessing high memory is a little more costly
1456	  than low memory, as it needs to be mapped into the kernel first.
1457	  Note that increasing the kernel address space limits the range
1458	  available to user programs, making the address space there
1459	  tighter.  Selecting anything other than the default 3G/1G split
1460	  will also likely make your kernel incompatible with binary-only
1461	  kernel modules.
1462
1463	  If you are not absolutely sure what you are doing, leave this
1464	  option alone!
1465
1466	config VMSPLIT_3G
1467		bool "3G/1G user/kernel split"
1468	config VMSPLIT_3G_OPT
1469		depends on !X86_PAE
1470		bool "3G/1G user/kernel split (for full 1G low memory)"
1471	config VMSPLIT_2G
1472		bool "2G/2G user/kernel split"
1473	config VMSPLIT_2G_OPT
1474		depends on !X86_PAE
1475		bool "2G/2G user/kernel split (for full 2G low memory)"
1476	config VMSPLIT_1G
1477		bool "1G/3G user/kernel split"
1478endchoice
1479
1480config PAGE_OFFSET
1481	hex
1482	default 0xB0000000 if VMSPLIT_3G_OPT
1483	default 0x80000000 if VMSPLIT_2G
1484	default 0x78000000 if VMSPLIT_2G_OPT
1485	default 0x40000000 if VMSPLIT_1G
1486	default 0xC0000000
1487	depends on X86_32
1488
1489config HIGHMEM
1490	def_bool y
1491	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1492
1493config X86_PAE
1494	bool "PAE (Physical Address Extension) Support"
1495	depends on X86_32 && !HIGHMEM4G
1496	select PHYS_ADDR_T_64BIT
1497	select SWIOTLB
1498	help
1499	  PAE is required for NX support, and furthermore enables
1500	  larger swapspace support for non-overcommit purposes. It
1501	  has the cost of more pagetable lookup overhead, and also
1502	  consumes more pagetable space per process.
1503
1504config X86_5LEVEL
1505	bool "Enable 5-level page tables support"
1506	default y
1507	select DYNAMIC_MEMORY_LAYOUT
1508	select SPARSEMEM_VMEMMAP
1509	depends on X86_64
1510	help
1511	  5-level paging enables access to larger address space:
1512	  upto 128 PiB of virtual address space and 4 PiB of
1513	  physical address space.
1514
1515	  It will be supported by future Intel CPUs.
1516
1517	  A kernel with the option enabled can be booted on machines that
1518	  support 4- or 5-level paging.
1519
1520	  See Documentation/x86/x86_64/5level-paging.rst for more
1521	  information.
1522
1523	  Say N if unsure.
1524
1525config X86_DIRECT_GBPAGES
1526	def_bool y
1527	depends on X86_64
1528	help
1529	  Certain kernel features effectively disable kernel
1530	  linear 1 GB mappings (even if the CPU otherwise
1531	  supports them), so don't confuse the user by printing
1532	  that we have them enabled.
1533
1534config X86_CPA_STATISTICS
1535	bool "Enable statistic for Change Page Attribute"
1536	depends on DEBUG_FS
1537	help
1538	  Expose statistics about the Change Page Attribute mechanism, which
1539	  helps to determine the effectiveness of preserving large and huge
1540	  page mappings when mapping protections are changed.
1541
1542config X86_MEM_ENCRYPT
1543	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1544	select DYNAMIC_PHYSICAL_MASK
1545	def_bool n
1546
1547config AMD_MEM_ENCRYPT
1548	bool "AMD Secure Memory Encryption (SME) support"
1549	depends on X86_64 && CPU_SUP_AMD
1550	select DMA_COHERENT_POOL
1551	select ARCH_USE_MEMREMAP_PROT
1552	select INSTRUCTION_DECODER
1553	select ARCH_HAS_CC_PLATFORM
1554	select X86_MEM_ENCRYPT
1555	help
1556	  Say yes to enable support for the encryption of system memory.
1557	  This requires an AMD processor that supports Secure Memory
1558	  Encryption (SME).
1559
1560config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1561	bool "Activate AMD Secure Memory Encryption (SME) by default"
1562	depends on AMD_MEM_ENCRYPT
1563	help
1564	  Say yes to have system memory encrypted by default if running on
1565	  an AMD processor that supports Secure Memory Encryption (SME).
1566
1567	  If set to Y, then the encryption of system memory can be
1568	  deactivated with the mem_encrypt=off command line option.
1569
1570	  If set to N, then the encryption of system memory can be
1571	  activated with the mem_encrypt=on command line option.
1572
1573# Common NUMA Features
1574config NUMA
1575	bool "NUMA Memory Allocation and Scheduler Support"
1576	depends on SMP
1577	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1578	default y if X86_BIGSMP
1579	select USE_PERCPU_NUMA_NODE_ID
1580	help
1581	  Enable NUMA (Non-Uniform Memory Access) support.
1582
1583	  The kernel will try to allocate memory used by a CPU on the
1584	  local memory controller of the CPU and add some more
1585	  NUMA awareness to the kernel.
1586
1587	  For 64-bit this is recommended if the system is Intel Core i7
1588	  (or later), AMD Opteron, or EM64T NUMA.
1589
1590	  For 32-bit this is only needed if you boot a 32-bit
1591	  kernel on a 64-bit NUMA platform.
1592
1593	  Otherwise, you should say N.
1594
1595config AMD_NUMA
1596	def_bool y
1597	prompt "Old style AMD Opteron NUMA detection"
1598	depends on X86_64 && NUMA && PCI
1599	help
1600	  Enable AMD NUMA node topology detection.  You should say Y here if
1601	  you have a multi processor AMD system. This uses an old method to
1602	  read the NUMA configuration directly from the builtin Northbridge
1603	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1604	  which also takes priority if both are compiled in.
1605
1606config X86_64_ACPI_NUMA
1607	def_bool y
1608	prompt "ACPI NUMA detection"
1609	depends on X86_64 && NUMA && ACPI && PCI
1610	select ACPI_NUMA
1611	help
1612	  Enable ACPI SRAT based node topology detection.
1613
1614config NUMA_EMU
1615	bool "NUMA emulation"
1616	depends on NUMA
1617	help
1618	  Enable NUMA emulation. A flat machine will be split
1619	  into virtual nodes when booted with "numa=fake=N", where N is the
1620	  number of nodes. This is only useful for debugging.
1621
1622config NODES_SHIFT
1623	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1624	range 1 10
1625	default "10" if MAXSMP
1626	default "6" if X86_64
1627	default "3"
1628	depends on NUMA
1629	help
1630	  Specify the maximum number of NUMA Nodes available on the target
1631	  system.  Increases memory reserved to accommodate various tables.
1632
1633config ARCH_FLATMEM_ENABLE
1634	def_bool y
1635	depends on X86_32 && !NUMA
1636
1637config ARCH_SPARSEMEM_ENABLE
1638	def_bool y
1639	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1640	select SPARSEMEM_STATIC if X86_32
1641	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1642
1643config ARCH_SPARSEMEM_DEFAULT
1644	def_bool X86_64 || (NUMA && X86_32)
1645
1646config ARCH_SELECT_MEMORY_MODEL
1647	def_bool y
1648	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1649
1650config ARCH_MEMORY_PROBE
1651	bool "Enable sysfs memory/probe interface"
1652	depends on MEMORY_HOTPLUG
1653	help
1654	  This option enables a sysfs memory/probe interface for testing.
1655	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1656	  If you are unsure how to answer this question, answer N.
1657
1658config ARCH_PROC_KCORE_TEXT
1659	def_bool y
1660	depends on X86_64 && PROC_KCORE
1661
1662config ILLEGAL_POINTER_VALUE
1663	hex
1664	default 0 if X86_32
1665	default 0xdead000000000000 if X86_64
1666
1667config X86_PMEM_LEGACY_DEVICE
1668	bool
1669
1670config X86_PMEM_LEGACY
1671	tristate "Support non-standard NVDIMMs and ADR protected memory"
1672	depends on PHYS_ADDR_T_64BIT
1673	depends on BLK_DEV
1674	select X86_PMEM_LEGACY_DEVICE
1675	select NUMA_KEEP_MEMINFO if NUMA
1676	select LIBNVDIMM
1677	help
1678	  Treat memory marked using the non-standard e820 type of 12 as used
1679	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1680	  The kernel will offer these regions to the 'pmem' driver so
1681	  they can be used for persistent storage.
1682
1683	  Say Y if unsure.
1684
1685config HIGHPTE
1686	bool "Allocate 3rd-level pagetables from highmem"
1687	depends on HIGHMEM
1688	help
1689	  The VM uses one page table entry for each page of physical memory.
1690	  For systems with a lot of RAM, this can be wasteful of precious
1691	  low memory.  Setting this option will put user-space page table
1692	  entries in high memory.
1693
1694config X86_CHECK_BIOS_CORRUPTION
1695	bool "Check for low memory corruption"
1696	help
1697	  Periodically check for memory corruption in low memory, which
1698	  is suspected to be caused by BIOS.  Even when enabled in the
1699	  configuration, it is disabled at runtime.  Enable it by
1700	  setting "memory_corruption_check=1" on the kernel command
1701	  line.  By default it scans the low 64k of memory every 60
1702	  seconds; see the memory_corruption_check_size and
1703	  memory_corruption_check_period parameters in
1704	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1705
1706	  When enabled with the default parameters, this option has
1707	  almost no overhead, as it reserves a relatively small amount
1708	  of memory and scans it infrequently.  It both detects corruption
1709	  and prevents it from affecting the running system.
1710
1711	  It is, however, intended as a diagnostic tool; if repeatable
1712	  BIOS-originated corruption always affects the same memory,
1713	  you can use memmap= to prevent the kernel from using that
1714	  memory.
1715
1716config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1717	bool "Set the default setting of memory_corruption_check"
1718	depends on X86_CHECK_BIOS_CORRUPTION
1719	default y
1720	help
1721	  Set whether the default state of memory_corruption_check is
1722	  on or off.
1723
1724config MATH_EMULATION
1725	bool
1726	depends on MODIFY_LDT_SYSCALL
1727	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1728	help
1729	  Linux can emulate a math coprocessor (used for floating point
1730	  operations) if you don't have one. 486DX and Pentium processors have
1731	  a math coprocessor built in, 486SX and 386 do not, unless you added
1732	  a 487DX or 387, respectively. (The messages during boot time can
1733	  give you some hints here ["man dmesg"].) Everyone needs either a
1734	  coprocessor or this emulation.
1735
1736	  If you don't have a math coprocessor, you need to say Y here; if you
1737	  say Y here even though you have a coprocessor, the coprocessor will
1738	  be used nevertheless. (This behavior can be changed with the kernel
1739	  command line option "no387", which comes handy if your coprocessor
1740	  is broken. Try "man bootparam" or see the documentation of your boot
1741	  loader (lilo or loadlin) about how to pass options to the kernel at
1742	  boot time.) This means that it is a good idea to say Y here if you
1743	  intend to use this kernel on different machines.
1744
1745	  More information about the internals of the Linux math coprocessor
1746	  emulation can be found in <file:arch/x86/math-emu/README>.
1747
1748	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1749	  kernel, it won't hurt.
1750
1751config MTRR
1752	def_bool y
1753	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1754	help
1755	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1756	  the Memory Type Range Registers (MTRRs) may be used to control
1757	  processor access to memory ranges. This is most useful if you have
1758	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1759	  allows bus write transfers to be combined into a larger transfer
1760	  before bursting over the PCI/AGP bus. This can increase performance
1761	  of image write operations 2.5 times or more. Saying Y here creates a
1762	  /proc/mtrr file which may be used to manipulate your processor's
1763	  MTRRs. Typically the X server should use this.
1764
1765	  This code has a reasonably generic interface so that similar
1766	  control registers on other processors can be easily supported
1767	  as well:
1768
1769	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1770	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1771	  these, the ARRs are used to emulate the MTRRs.
1772	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1773	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1774	  write-combining. All of these processors are supported by this code
1775	  and it makes sense to say Y here if you have one of them.
1776
1777	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1778	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1779	  can lead to all sorts of problems, so it's good to say Y here.
1780
1781	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1782	  just add about 9 KB to your kernel.
1783
1784	  See <file:Documentation/x86/mtrr.rst> for more information.
1785
1786config MTRR_SANITIZER
1787	def_bool y
1788	prompt "MTRR cleanup support"
1789	depends on MTRR
1790	help
1791	  Convert MTRR layout from continuous to discrete, so X drivers can
1792	  add writeback entries.
1793
1794	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1795	  The largest mtrr entry size for a continuous block can be set with
1796	  mtrr_chunk_size.
1797
1798	  If unsure, say Y.
1799
1800config MTRR_SANITIZER_ENABLE_DEFAULT
1801	int "MTRR cleanup enable value (0-1)"
1802	range 0 1
1803	default "0"
1804	depends on MTRR_SANITIZER
1805	help
1806	  Enable mtrr cleanup default value
1807
1808config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1809	int "MTRR cleanup spare reg num (0-7)"
1810	range 0 7
1811	default "1"
1812	depends on MTRR_SANITIZER
1813	help
1814	  mtrr cleanup spare entries default, it can be changed via
1815	  mtrr_spare_reg_nr=N on the kernel command line.
1816
1817config X86_PAT
1818	def_bool y
1819	prompt "x86 PAT support" if EXPERT
1820	depends on MTRR
1821	help
1822	  Use PAT attributes to setup page level cache control.
1823
1824	  PATs are the modern equivalents of MTRRs and are much more
1825	  flexible than MTRRs.
1826
1827	  Say N here if you see bootup problems (boot crash, boot hang,
1828	  spontaneous reboots) or a non-working video driver.
1829
1830	  If unsure, say Y.
1831
1832config ARCH_USES_PG_UNCACHED
1833	def_bool y
1834	depends on X86_PAT
1835
1836config ARCH_RANDOM
1837	def_bool y
1838	prompt "x86 architectural random number generator" if EXPERT
1839	help
1840	  Enable the x86 architectural RDRAND instruction
1841	  (Intel Bull Mountain technology) to generate random numbers.
1842	  If supported, this is a high bandwidth, cryptographically
1843	  secure hardware random number generator.
1844
1845config X86_UMIP
1846	def_bool y
1847	prompt "User Mode Instruction Prevention" if EXPERT
1848	help
1849	  User Mode Instruction Prevention (UMIP) is a security feature in
1850	  some x86 processors. If enabled, a general protection fault is
1851	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1852	  executed in user mode. These instructions unnecessarily expose
1853	  information about the hardware state.
1854
1855	  The vast majority of applications do not use these instructions.
1856	  For the very few that do, software emulation is provided in
1857	  specific cases in protected and virtual-8086 modes. Emulated
1858	  results are dummy.
1859
1860config CC_HAS_IBT
1861	# GCC >= 9 and binutils >= 2.29
1862	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1863	# Clang/LLVM >= 14
1864	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1865	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1866	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1867		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1868		  $(as-instr,endbr64)
1869
1870config X86_KERNEL_IBT
1871	prompt "Indirect Branch Tracking"
1872	bool
1873	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1874	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1875	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1876	select OBJTOOL
1877	help
1878	  Build the kernel with support for Indirect Branch Tracking, a
1879	  hardware support course-grain forward-edge Control Flow Integrity
1880	  protection. It enforces that all indirect calls must land on
1881	  an ENDBR instruction, as such, the compiler will instrument the
1882	  code with them to make this happen.
1883
1884	  In addition to building the kernel with IBT, seal all functions that
1885	  are not indirect call targets, avoiding them ever becoming one.
1886
1887	  This requires LTO like objtool runs and will slow down the build. It
1888	  does significantly reduce the number of ENDBR instructions in the
1889	  kernel image.
1890
1891config X86_INTEL_MEMORY_PROTECTION_KEYS
1892	prompt "Memory Protection Keys"
1893	def_bool y
1894	# Note: only available in 64-bit mode
1895	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1896	select ARCH_USES_HIGH_VMA_FLAGS
1897	select ARCH_HAS_PKEYS
1898	help
1899	  Memory Protection Keys provides a mechanism for enforcing
1900	  page-based protections, but without requiring modification of the
1901	  page tables when an application changes protection domains.
1902
1903	  For details, see Documentation/core-api/protection-keys.rst
1904
1905	  If unsure, say y.
1906
1907choice
1908	prompt "TSX enable mode"
1909	depends on CPU_SUP_INTEL
1910	default X86_INTEL_TSX_MODE_OFF
1911	help
1912	  Intel's TSX (Transactional Synchronization Extensions) feature
1913	  allows to optimize locking protocols through lock elision which
1914	  can lead to a noticeable performance boost.
1915
1916	  On the other hand it has been shown that TSX can be exploited
1917	  to form side channel attacks (e.g. TAA) and chances are there
1918	  will be more of those attacks discovered in the future.
1919
1920	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1921	  might override this decision by tsx=on the command line parameter.
1922	  Even with TSX enabled, the kernel will attempt to enable the best
1923	  possible TAA mitigation setting depending on the microcode available
1924	  for the particular machine.
1925
1926	  This option allows to set the default tsx mode between tsx=on, =off
1927	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1928	  details.
1929
1930	  Say off if not sure, auto if TSX is in use but it should be used on safe
1931	  platforms or on if TSX is in use and the security aspect of tsx is not
1932	  relevant.
1933
1934config X86_INTEL_TSX_MODE_OFF
1935	bool "off"
1936	help
1937	  TSX is disabled if possible - equals to tsx=off command line parameter.
1938
1939config X86_INTEL_TSX_MODE_ON
1940	bool "on"
1941	help
1942	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1943	  line parameter.
1944
1945config X86_INTEL_TSX_MODE_AUTO
1946	bool "auto"
1947	help
1948	  TSX is enabled on TSX capable HW that is believed to be safe against
1949	  side channel attacks- equals the tsx=auto command line parameter.
1950endchoice
1951
1952config X86_SGX
1953	bool "Software Guard eXtensions (SGX)"
1954	depends on X86_64 && CPU_SUP_INTEL
1955	depends on CRYPTO=y
1956	depends on CRYPTO_SHA256=y
1957	select SRCU
1958	select MMU_NOTIFIER
1959	select NUMA_KEEP_MEMINFO if NUMA
1960	select XARRAY_MULTI
1961	help
1962	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1963	  that can be used by applications to set aside private regions of code
1964	  and data, referred to as enclaves. An enclave's private memory can
1965	  only be accessed by code running within the enclave. Accesses from
1966	  outside the enclave, including other enclaves, are disallowed by
1967	  hardware.
1968
1969	  If unsure, say N.
1970
1971config EFI
1972	bool "EFI runtime service support"
1973	depends on ACPI
1974	select UCS2_STRING
1975	select EFI_RUNTIME_WRAPPERS
1976	select ARCH_USE_MEMREMAP_PROT
1977	help
1978	  This enables the kernel to use EFI runtime services that are
1979	  available (such as the EFI variable services).
1980
1981	  This option is only useful on systems that have EFI firmware.
1982	  In addition, you should use the latest ELILO loader available
1983	  at <http://elilo.sourceforge.net> in order to take advantage
1984	  of EFI runtime services. However, even with this option, the
1985	  resultant kernel should continue to boot on existing non-EFI
1986	  platforms.
1987
1988config EFI_STUB
1989	bool "EFI stub support"
1990	depends on EFI
1991	depends on $(cc-option,-mabi=ms) || X86_32
1992	select RELOCATABLE
1993	help
1994	  This kernel feature allows a bzImage to be loaded directly
1995	  by EFI firmware without the use of a bootloader.
1996
1997	  See Documentation/admin-guide/efi-stub.rst for more information.
1998
1999config EFI_MIXED
2000	bool "EFI mixed-mode support"
2001	depends on EFI_STUB && X86_64
2002	help
2003	  Enabling this feature allows a 64-bit kernel to be booted
2004	  on a 32-bit firmware, provided that your CPU supports 64-bit
2005	  mode.
2006
2007	  Note that it is not possible to boot a mixed-mode enabled
2008	  kernel via the EFI boot stub - a bootloader that supports
2009	  the EFI handover protocol must be used.
2010
2011	  If unsure, say N.
2012
2013source "kernel/Kconfig.hz"
2014
2015config KEXEC
2016	bool "kexec system call"
2017	select KEXEC_CORE
2018	help
2019	  kexec is a system call that implements the ability to shutdown your
2020	  current kernel, and to start another kernel.  It is like a reboot
2021	  but it is independent of the system firmware.   And like a reboot
2022	  you can start any kernel with it, not just Linux.
2023
2024	  The name comes from the similarity to the exec system call.
2025
2026	  It is an ongoing process to be certain the hardware in a machine
2027	  is properly shutdown, so do not be surprised if this code does not
2028	  initially work for you.  As of this writing the exact hardware
2029	  interface is strongly in flux, so no good recommendation can be
2030	  made.
2031
2032config KEXEC_FILE
2033	bool "kexec file based system call"
2034	select KEXEC_CORE
2035	select BUILD_BIN2C
2036	depends on X86_64
2037	depends on CRYPTO=y
2038	depends on CRYPTO_SHA256=y
2039	help
2040	  This is new version of kexec system call. This system call is
2041	  file based and takes file descriptors as system call argument
2042	  for kernel and initramfs as opposed to list of segments as
2043	  accepted by previous system call.
2044
2045config ARCH_HAS_KEXEC_PURGATORY
2046	def_bool KEXEC_FILE
2047
2048config KEXEC_SIG
2049	bool "Verify kernel signature during kexec_file_load() syscall"
2050	depends on KEXEC_FILE
2051	help
2052
2053	  This option makes the kexec_file_load() syscall check for a valid
2054	  signature of the kernel image.  The image can still be loaded without
2055	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2056	  there's a signature that we can check, then it must be valid.
2057
2058	  In addition to this option, you need to enable signature
2059	  verification for the corresponding kernel image type being
2060	  loaded in order for this to work.
2061
2062config KEXEC_SIG_FORCE
2063	bool "Require a valid signature in kexec_file_load() syscall"
2064	depends on KEXEC_SIG
2065	help
2066	  This option makes kernel signature verification mandatory for
2067	  the kexec_file_load() syscall.
2068
2069config KEXEC_BZIMAGE_VERIFY_SIG
2070	bool "Enable bzImage signature verification support"
2071	depends on KEXEC_SIG
2072	depends on SIGNED_PE_FILE_VERIFICATION
2073	select SYSTEM_TRUSTED_KEYRING
2074	help
2075	  Enable bzImage signature verification support.
2076
2077config CRASH_DUMP
2078	bool "kernel crash dumps"
2079	depends on X86_64 || (X86_32 && HIGHMEM)
2080	help
2081	  Generate crash dump after being started by kexec.
2082	  This should be normally only set in special crash dump kernels
2083	  which are loaded in the main kernel with kexec-tools into
2084	  a specially reserved region and then later executed after
2085	  a crash by kdump/kexec. The crash dump kernel must be compiled
2086	  to a memory address not used by the main kernel or BIOS using
2087	  PHYSICAL_START, or it must be built as a relocatable image
2088	  (CONFIG_RELOCATABLE=y).
2089	  For more details see Documentation/admin-guide/kdump/kdump.rst
2090
2091config KEXEC_JUMP
2092	bool "kexec jump"
2093	depends on KEXEC && HIBERNATION
2094	help
2095	  Jump between original kernel and kexeced kernel and invoke
2096	  code in physical address mode via KEXEC
2097
2098config PHYSICAL_START
2099	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2100	default "0x1000000"
2101	help
2102	  This gives the physical address where the kernel is loaded.
2103
2104	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2105	  bzImage will decompress itself to above physical address and
2106	  run from there. Otherwise, bzImage will run from the address where
2107	  it has been loaded by the boot loader and will ignore above physical
2108	  address.
2109
2110	  In normal kdump cases one does not have to set/change this option
2111	  as now bzImage can be compiled as a completely relocatable image
2112	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2113	  address. This option is mainly useful for the folks who don't want
2114	  to use a bzImage for capturing the crash dump and want to use a
2115	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2116	  to be specifically compiled to run from a specific memory area
2117	  (normally a reserved region) and this option comes handy.
2118
2119	  So if you are using bzImage for capturing the crash dump,
2120	  leave the value here unchanged to 0x1000000 and set
2121	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2122	  for capturing the crash dump change this value to start of
2123	  the reserved region.  In other words, it can be set based on
2124	  the "X" value as specified in the "crashkernel=YM@XM"
2125	  command line boot parameter passed to the panic-ed
2126	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2127	  for more details about crash dumps.
2128
2129	  Usage of bzImage for capturing the crash dump is recommended as
2130	  one does not have to build two kernels. Same kernel can be used
2131	  as production kernel and capture kernel. Above option should have
2132	  gone away after relocatable bzImage support is introduced. But it
2133	  is present because there are users out there who continue to use
2134	  vmlinux for dump capture. This option should go away down the
2135	  line.
2136
2137	  Don't change this unless you know what you are doing.
2138
2139config RELOCATABLE
2140	bool "Build a relocatable kernel"
2141	default y
2142	help
2143	  This builds a kernel image that retains relocation information
2144	  so it can be loaded someplace besides the default 1MB.
2145	  The relocations tend to make the kernel binary about 10% larger,
2146	  but are discarded at runtime.
2147
2148	  One use is for the kexec on panic case where the recovery kernel
2149	  must live at a different physical address than the primary
2150	  kernel.
2151
2152	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2153	  it has been loaded at and the compile time physical address
2154	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2155
2156config RANDOMIZE_BASE
2157	bool "Randomize the address of the kernel image (KASLR)"
2158	depends on RELOCATABLE
2159	default y
2160	help
2161	  In support of Kernel Address Space Layout Randomization (KASLR),
2162	  this randomizes the physical address at which the kernel image
2163	  is decompressed and the virtual address where the kernel
2164	  image is mapped, as a security feature that deters exploit
2165	  attempts relying on knowledge of the location of kernel
2166	  code internals.
2167
2168	  On 64-bit, the kernel physical and virtual addresses are
2169	  randomized separately. The physical address will be anywhere
2170	  between 16MB and the top of physical memory (up to 64TB). The
2171	  virtual address will be randomized from 16MB up to 1GB (9 bits
2172	  of entropy). Note that this also reduces the memory space
2173	  available to kernel modules from 1.5GB to 1GB.
2174
2175	  On 32-bit, the kernel physical and virtual addresses are
2176	  randomized together. They will be randomized from 16MB up to
2177	  512MB (8 bits of entropy).
2178
2179	  Entropy is generated using the RDRAND instruction if it is
2180	  supported. If RDTSC is supported, its value is mixed into
2181	  the entropy pool as well. If neither RDRAND nor RDTSC are
2182	  supported, then entropy is read from the i8254 timer. The
2183	  usable entropy is limited by the kernel being built using
2184	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2185	  minimum of 2MB. As a result, only 10 bits of entropy are
2186	  theoretically possible, but the implementations are further
2187	  limited due to memory layouts.
2188
2189	  If unsure, say Y.
2190
2191# Relocation on x86 needs some additional build support
2192config X86_NEED_RELOCS
2193	def_bool y
2194	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2195
2196config PHYSICAL_ALIGN
2197	hex "Alignment value to which kernel should be aligned"
2198	default "0x200000"
2199	range 0x2000 0x1000000 if X86_32
2200	range 0x200000 0x1000000 if X86_64
2201	help
2202	  This value puts the alignment restrictions on physical address
2203	  where kernel is loaded and run from. Kernel is compiled for an
2204	  address which meets above alignment restriction.
2205
2206	  If bootloader loads the kernel at a non-aligned address and
2207	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2208	  address aligned to above value and run from there.
2209
2210	  If bootloader loads the kernel at a non-aligned address and
2211	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2212	  load address and decompress itself to the address it has been
2213	  compiled for and run from there. The address for which kernel is
2214	  compiled already meets above alignment restrictions. Hence the
2215	  end result is that kernel runs from a physical address meeting
2216	  above alignment restrictions.
2217
2218	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2219	  this value must be a multiple of 0x200000.
2220
2221	  Don't change this unless you know what you are doing.
2222
2223config DYNAMIC_MEMORY_LAYOUT
2224	bool
2225	help
2226	  This option makes base addresses of vmalloc and vmemmap as well as
2227	  __PAGE_OFFSET movable during boot.
2228
2229config RANDOMIZE_MEMORY
2230	bool "Randomize the kernel memory sections"
2231	depends on X86_64
2232	depends on RANDOMIZE_BASE
2233	select DYNAMIC_MEMORY_LAYOUT
2234	default RANDOMIZE_BASE
2235	help
2236	  Randomizes the base virtual address of kernel memory sections
2237	  (physical memory mapping, vmalloc & vmemmap). This security feature
2238	  makes exploits relying on predictable memory locations less reliable.
2239
2240	  The order of allocations remains unchanged. Entropy is generated in
2241	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2242	  configuration have in average 30,000 different possible virtual
2243	  addresses for each memory section.
2244
2245	  If unsure, say Y.
2246
2247config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2248	hex "Physical memory mapping padding" if EXPERT
2249	depends on RANDOMIZE_MEMORY
2250	default "0xa" if MEMORY_HOTPLUG
2251	default "0x0"
2252	range 0x1 0x40 if MEMORY_HOTPLUG
2253	range 0x0 0x40
2254	help
2255	  Define the padding in terabytes added to the existing physical
2256	  memory size during kernel memory randomization. It is useful
2257	  for memory hotplug support but reduces the entropy available for
2258	  address randomization.
2259
2260	  If unsure, leave at the default value.
2261
2262config HOTPLUG_CPU
2263	def_bool y
2264	depends on SMP
2265
2266config BOOTPARAM_HOTPLUG_CPU0
2267	bool "Set default setting of cpu0_hotpluggable"
2268	depends on HOTPLUG_CPU
2269	help
2270	  Set whether default state of cpu0_hotpluggable is on or off.
2271
2272	  Say Y here to enable CPU0 hotplug by default. If this switch
2273	  is turned on, there is no need to give cpu0_hotplug kernel
2274	  parameter and the CPU0 hotplug feature is enabled by default.
2275
2276	  Please note: there are two known CPU0 dependencies if you want
2277	  to enable the CPU0 hotplug feature either by this switch or by
2278	  cpu0_hotplug kernel parameter.
2279
2280	  First, resume from hibernate or suspend always starts from CPU0.
2281	  So hibernate and suspend are prevented if CPU0 is offline.
2282
2283	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2284	  offline if any interrupt can not migrate out of CPU0. There may
2285	  be other CPU0 dependencies.
2286
2287	  Please make sure the dependencies are under your control before
2288	  you enable this feature.
2289
2290	  Say N if you don't want to enable CPU0 hotplug feature by default.
2291	  You still can enable the CPU0 hotplug feature at boot by kernel
2292	  parameter cpu0_hotplug.
2293
2294config DEBUG_HOTPLUG_CPU0
2295	def_bool n
2296	prompt "Debug CPU0 hotplug"
2297	depends on HOTPLUG_CPU
2298	help
2299	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2300	  soon as possible and boots up userspace with CPU0 offlined. User
2301	  can online CPU0 back after boot time.
2302
2303	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2304	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2305	  compilation or giving cpu0_hotplug kernel parameter at boot.
2306
2307	  If unsure, say N.
2308
2309config COMPAT_VDSO
2310	def_bool n
2311	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2312	depends on COMPAT_32
2313	help
2314	  Certain buggy versions of glibc will crash if they are
2315	  presented with a 32-bit vDSO that is not mapped at the address
2316	  indicated in its segment table.
2317
2318	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2319	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2320	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2321	  the only released version with the bug, but OpenSUSE 9
2322	  contains a buggy "glibc 2.3.2".
2323
2324	  The symptom of the bug is that everything crashes on startup, saying:
2325	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2326
2327	  Saying Y here changes the default value of the vdso32 boot
2328	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2329	  This works around the glibc bug but hurts performance.
2330
2331	  If unsure, say N: if you are compiling your own kernel, you
2332	  are unlikely to be using a buggy version of glibc.
2333
2334choice
2335	prompt "vsyscall table for legacy applications"
2336	depends on X86_64
2337	default LEGACY_VSYSCALL_XONLY
2338	help
2339	  Legacy user code that does not know how to find the vDSO expects
2340	  to be able to issue three syscalls by calling fixed addresses in
2341	  kernel space. Since this location is not randomized with ASLR,
2342	  it can be used to assist security vulnerability exploitation.
2343
2344	  This setting can be changed at boot time via the kernel command
2345	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2346	  is deprecated and can only be enabled using the kernel command
2347	  line.
2348
2349	  On a system with recent enough glibc (2.14 or newer) and no
2350	  static binaries, you can say None without a performance penalty
2351	  to improve security.
2352
2353	  If unsure, select "Emulate execution only".
2354
2355	config LEGACY_VSYSCALL_XONLY
2356		bool "Emulate execution only"
2357		help
2358		  The kernel traps and emulates calls into the fixed vsyscall
2359		  address mapping and does not allow reads.  This
2360		  configuration is recommended when userspace might use the
2361		  legacy vsyscall area but support for legacy binary
2362		  instrumentation of legacy code is not needed.  It mitigates
2363		  certain uses of the vsyscall area as an ASLR-bypassing
2364		  buffer.
2365
2366	config LEGACY_VSYSCALL_NONE
2367		bool "None"
2368		help
2369		  There will be no vsyscall mapping at all. This will
2370		  eliminate any risk of ASLR bypass due to the vsyscall
2371		  fixed address mapping. Attempts to use the vsyscalls
2372		  will be reported to dmesg, so that either old or
2373		  malicious userspace programs can be identified.
2374
2375endchoice
2376
2377config CMDLINE_BOOL
2378	bool "Built-in kernel command line"
2379	help
2380	  Allow for specifying boot arguments to the kernel at
2381	  build time.  On some systems (e.g. embedded ones), it is
2382	  necessary or convenient to provide some or all of the
2383	  kernel boot arguments with the kernel itself (that is,
2384	  to not rely on the boot loader to provide them.)
2385
2386	  To compile command line arguments into the kernel,
2387	  set this option to 'Y', then fill in the
2388	  boot arguments in CONFIG_CMDLINE.
2389
2390	  Systems with fully functional boot loaders (i.e. non-embedded)
2391	  should leave this option set to 'N'.
2392
2393config CMDLINE
2394	string "Built-in kernel command string"
2395	depends on CMDLINE_BOOL
2396	default ""
2397	help
2398	  Enter arguments here that should be compiled into the kernel
2399	  image and used at boot time.  If the boot loader provides a
2400	  command line at boot time, it is appended to this string to
2401	  form the full kernel command line, when the system boots.
2402
2403	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2404	  change this behavior.
2405
2406	  In most cases, the command line (whether built-in or provided
2407	  by the boot loader) should specify the device for the root
2408	  file system.
2409
2410config CMDLINE_OVERRIDE
2411	bool "Built-in command line overrides boot loader arguments"
2412	depends on CMDLINE_BOOL && CMDLINE != ""
2413	help
2414	  Set this option to 'Y' to have the kernel ignore the boot loader
2415	  command line, and use ONLY the built-in command line.
2416
2417	  This is used to work around broken boot loaders.  This should
2418	  be set to 'N' under normal conditions.
2419
2420config MODIFY_LDT_SYSCALL
2421	bool "Enable the LDT (local descriptor table)" if EXPERT
2422	default y
2423	help
2424	  Linux can allow user programs to install a per-process x86
2425	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2426	  call.  This is required to run 16-bit or segmented code such as
2427	  DOSEMU or some Wine programs.  It is also used by some very old
2428	  threading libraries.
2429
2430	  Enabling this feature adds a small amount of overhead to
2431	  context switches and increases the low-level kernel attack
2432	  surface.  Disabling it removes the modify_ldt(2) system call.
2433
2434	  Saying 'N' here may make sense for embedded or server kernels.
2435
2436config STRICT_SIGALTSTACK_SIZE
2437	bool "Enforce strict size checking for sigaltstack"
2438	depends on DYNAMIC_SIGFRAME
2439	help
2440	  For historical reasons MINSIGSTKSZ is a constant which became
2441	  already too small with AVX512 support. Add a mechanism to
2442	  enforce strict checking of the sigaltstack size against the
2443	  real size of the FPU frame. This option enables the check
2444	  by default. It can also be controlled via the kernel command
2445	  line option 'strict_sas_size' independent of this config
2446	  switch. Enabling it might break existing applications which
2447	  allocate a too small sigaltstack but 'work' because they
2448	  never get a signal delivered.
2449
2450	  Say 'N' unless you want to really enforce this check.
2451
2452source "kernel/livepatch/Kconfig"
2453
2454endmenu
2455
2456config ARCH_HAS_ADD_PAGES
2457	def_bool y
2458	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2459
2460config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2461	def_bool y
2462
2463menu "Power management and ACPI options"
2464
2465config ARCH_HIBERNATION_HEADER
2466	def_bool y
2467	depends on HIBERNATION
2468
2469source "kernel/power/Kconfig"
2470
2471source "drivers/acpi/Kconfig"
2472
2473config X86_APM_BOOT
2474	def_bool y
2475	depends on APM
2476
2477menuconfig APM
2478	tristate "APM (Advanced Power Management) BIOS support"
2479	depends on X86_32 && PM_SLEEP
2480	help
2481	  APM is a BIOS specification for saving power using several different
2482	  techniques. This is mostly useful for battery powered laptops with
2483	  APM compliant BIOSes. If you say Y here, the system time will be
2484	  reset after a RESUME operation, the /proc/apm device will provide
2485	  battery status information, and user-space programs will receive
2486	  notification of APM "events" (e.g. battery status change).
2487
2488	  If you select "Y" here, you can disable actual use of the APM
2489	  BIOS by passing the "apm=off" option to the kernel at boot time.
2490
2491	  Note that the APM support is almost completely disabled for
2492	  machines with more than one CPU.
2493
2494	  In order to use APM, you will need supporting software. For location
2495	  and more information, read <file:Documentation/power/apm-acpi.rst>
2496	  and the Battery Powered Linux mini-HOWTO, available from
2497	  <http://www.tldp.org/docs.html#howto>.
2498
2499	  This driver does not spin down disk drives (see the hdparm(8)
2500	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2501	  VESA-compliant "green" monitors.
2502
2503	  This driver does not support the TI 4000M TravelMate and the ACER
2504	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2505	  desktop machines also don't have compliant BIOSes, and this driver
2506	  may cause those machines to panic during the boot phase.
2507
2508	  Generally, if you don't have a battery in your machine, there isn't
2509	  much point in using this driver and you should say N. If you get
2510	  random kernel OOPSes or reboots that don't seem to be related to
2511	  anything, try disabling/enabling this option (or disabling/enabling
2512	  APM in your BIOS).
2513
2514	  Some other things you should try when experiencing seemingly random,
2515	  "weird" problems:
2516
2517	  1) make sure that you have enough swap space and that it is
2518	  enabled.
2519	  2) pass the "no-hlt" option to the kernel
2520	  3) switch on floating point emulation in the kernel and pass
2521	  the "no387" option to the kernel
2522	  4) pass the "floppy=nodma" option to the kernel
2523	  5) pass the "mem=4M" option to the kernel (thereby disabling
2524	  all but the first 4 MB of RAM)
2525	  6) make sure that the CPU is not over clocked.
2526	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2527	  8) disable the cache from your BIOS settings
2528	  9) install a fan for the video card or exchange video RAM
2529	  10) install a better fan for the CPU
2530	  11) exchange RAM chips
2531	  12) exchange the motherboard.
2532
2533	  To compile this driver as a module, choose M here: the
2534	  module will be called apm.
2535
2536if APM
2537
2538config APM_IGNORE_USER_SUSPEND
2539	bool "Ignore USER SUSPEND"
2540	help
2541	  This option will ignore USER SUSPEND requests. On machines with a
2542	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2543	  series notebooks, it is necessary to say Y because of a BIOS bug.
2544
2545config APM_DO_ENABLE
2546	bool "Enable PM at boot time"
2547	help
2548	  Enable APM features at boot time. From page 36 of the APM BIOS
2549	  specification: "When disabled, the APM BIOS does not automatically
2550	  power manage devices, enter the Standby State, enter the Suspend
2551	  State, or take power saving steps in response to CPU Idle calls."
2552	  This driver will make CPU Idle calls when Linux is idle (unless this
2553	  feature is turned off -- see "Do CPU IDLE calls", below). This
2554	  should always save battery power, but more complicated APM features
2555	  will be dependent on your BIOS implementation. You may need to turn
2556	  this option off if your computer hangs at boot time when using APM
2557	  support, or if it beeps continuously instead of suspending. Turn
2558	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2559	  T400CDT. This is off by default since most machines do fine without
2560	  this feature.
2561
2562config APM_CPU_IDLE
2563	depends on CPU_IDLE
2564	bool "Make CPU Idle calls when idle"
2565	help
2566	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2567	  On some machines, this can activate improved power savings, such as
2568	  a slowed CPU clock rate, when the machine is idle. These idle calls
2569	  are made after the idle loop has run for some length of time (e.g.,
2570	  333 mS). On some machines, this will cause a hang at boot time or
2571	  whenever the CPU becomes idle. (On machines with more than one CPU,
2572	  this option does nothing.)
2573
2574config APM_DISPLAY_BLANK
2575	bool "Enable console blanking using APM"
2576	help
2577	  Enable console blanking using the APM. Some laptops can use this to
2578	  turn off the LCD backlight when the screen blanker of the Linux
2579	  virtual console blanks the screen. Note that this is only used by
2580	  the virtual console screen blanker, and won't turn off the backlight
2581	  when using the X Window system. This also doesn't have anything to
2582	  do with your VESA-compliant power-saving monitor. Further, this
2583	  option doesn't work for all laptops -- it might not turn off your
2584	  backlight at all, or it might print a lot of errors to the console,
2585	  especially if you are using gpm.
2586
2587config APM_ALLOW_INTS
2588	bool "Allow interrupts during APM BIOS calls"
2589	help
2590	  Normally we disable external interrupts while we are making calls to
2591	  the APM BIOS as a measure to lessen the effects of a badly behaving
2592	  BIOS implementation.  The BIOS should reenable interrupts if it
2593	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2594	  many of the newer IBM Thinkpads.  If you experience hangs when you
2595	  suspend, try setting this to Y.  Otherwise, say N.
2596
2597endif # APM
2598
2599source "drivers/cpufreq/Kconfig"
2600
2601source "drivers/cpuidle/Kconfig"
2602
2603source "drivers/idle/Kconfig"
2604
2605endmenu
2606
2607menu "Bus options (PCI etc.)"
2608
2609choice
2610	prompt "PCI access mode"
2611	depends on X86_32 && PCI
2612	default PCI_GOANY
2613	help
2614	  On PCI systems, the BIOS can be used to detect the PCI devices and
2615	  determine their configuration. However, some old PCI motherboards
2616	  have BIOS bugs and may crash if this is done. Also, some embedded
2617	  PCI-based systems don't have any BIOS at all. Linux can also try to
2618	  detect the PCI hardware directly without using the BIOS.
2619
2620	  With this option, you can specify how Linux should detect the
2621	  PCI devices. If you choose "BIOS", the BIOS will be used,
2622	  if you choose "Direct", the BIOS won't be used, and if you
2623	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2624	  If you choose "Any", the kernel will try MMCONFIG, then the
2625	  direct access method and falls back to the BIOS if that doesn't
2626	  work. If unsure, go with the default, which is "Any".
2627
2628config PCI_GOBIOS
2629	bool "BIOS"
2630
2631config PCI_GOMMCONFIG
2632	bool "MMConfig"
2633
2634config PCI_GODIRECT
2635	bool "Direct"
2636
2637config PCI_GOOLPC
2638	bool "OLPC XO-1"
2639	depends on OLPC
2640
2641config PCI_GOANY
2642	bool "Any"
2643
2644endchoice
2645
2646config PCI_BIOS
2647	def_bool y
2648	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2649
2650# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2651config PCI_DIRECT
2652	def_bool y
2653	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2654
2655config PCI_MMCONFIG
2656	bool "Support mmconfig PCI config space access" if X86_64
2657	default y
2658	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2659	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2660
2661config PCI_OLPC
2662	def_bool y
2663	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2664
2665config PCI_XEN
2666	def_bool y
2667	depends on PCI && XEN
2668
2669config MMCONF_FAM10H
2670	def_bool y
2671	depends on X86_64 && PCI_MMCONFIG && ACPI
2672
2673config PCI_CNB20LE_QUIRK
2674	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2675	depends on PCI
2676	help
2677	  Read the PCI windows out of the CNB20LE host bridge. This allows
2678	  PCI hotplug to work on systems with the CNB20LE chipset which do
2679	  not have ACPI.
2680
2681	  There's no public spec for this chipset, and this functionality
2682	  is known to be incomplete.
2683
2684	  You should say N unless you know you need this.
2685
2686config ISA_BUS
2687	bool "ISA bus support on modern systems" if EXPERT
2688	help
2689	  Expose ISA bus device drivers and options available for selection and
2690	  configuration. Enable this option if your target machine has an ISA
2691	  bus. ISA is an older system, displaced by PCI and newer bus
2692	  architectures -- if your target machine is modern, it probably does
2693	  not have an ISA bus.
2694
2695	  If unsure, say N.
2696
2697# x86_64 have no ISA slots, but can have ISA-style DMA.
2698config ISA_DMA_API
2699	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2700	default y
2701	help
2702	  Enables ISA-style DMA support for devices requiring such controllers.
2703	  If unsure, say Y.
2704
2705if X86_32
2706
2707config ISA
2708	bool "ISA support"
2709	help
2710	  Find out whether you have ISA slots on your motherboard.  ISA is the
2711	  name of a bus system, i.e. the way the CPU talks to the other stuff
2712	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2713	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2714	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2715
2716config SCx200
2717	tristate "NatSemi SCx200 support"
2718	help
2719	  This provides basic support for National Semiconductor's
2720	  (now AMD's) Geode processors.  The driver probes for the
2721	  PCI-IDs of several on-chip devices, so its a good dependency
2722	  for other scx200_* drivers.
2723
2724	  If compiled as a module, the driver is named scx200.
2725
2726config SCx200HR_TIMER
2727	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2728	depends on SCx200
2729	default y
2730	help
2731	  This driver provides a clocksource built upon the on-chip
2732	  27MHz high-resolution timer.  Its also a workaround for
2733	  NSC Geode SC-1100's buggy TSC, which loses time when the
2734	  processor goes idle (as is done by the scheduler).  The
2735	  other workaround is idle=poll boot option.
2736
2737config OLPC
2738	bool "One Laptop Per Child support"
2739	depends on !X86_PAE
2740	select GPIOLIB
2741	select OF
2742	select OF_PROMTREE
2743	select IRQ_DOMAIN
2744	select OLPC_EC
2745	help
2746	  Add support for detecting the unique features of the OLPC
2747	  XO hardware.
2748
2749config OLPC_XO1_PM
2750	bool "OLPC XO-1 Power Management"
2751	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2752	help
2753	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2754
2755config OLPC_XO1_RTC
2756	bool "OLPC XO-1 Real Time Clock"
2757	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2758	help
2759	  Add support for the XO-1 real time clock, which can be used as a
2760	  programmable wakeup source.
2761
2762config OLPC_XO1_SCI
2763	bool "OLPC XO-1 SCI extras"
2764	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2765	depends on INPUT=y
2766	select POWER_SUPPLY
2767	help
2768	  Add support for SCI-based features of the OLPC XO-1 laptop:
2769	   - EC-driven system wakeups
2770	   - Power button
2771	   - Ebook switch
2772	   - Lid switch
2773	   - AC adapter status updates
2774	   - Battery status updates
2775
2776config OLPC_XO15_SCI
2777	bool "OLPC XO-1.5 SCI extras"
2778	depends on OLPC && ACPI
2779	select POWER_SUPPLY
2780	help
2781	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2782	   - EC-driven system wakeups
2783	   - AC adapter status updates
2784	   - Battery status updates
2785
2786config ALIX
2787	bool "PCEngines ALIX System Support (LED setup)"
2788	select GPIOLIB
2789	help
2790	  This option enables system support for the PCEngines ALIX.
2791	  At present this just sets up LEDs for GPIO control on
2792	  ALIX2/3/6 boards.  However, other system specific setup should
2793	  get added here.
2794
2795	  Note: You must still enable the drivers for GPIO and LED support
2796	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2797
2798	  Note: You have to set alix.force=1 for boards with Award BIOS.
2799
2800config NET5501
2801	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2802	select GPIOLIB
2803	help
2804	  This option enables system support for the Soekris Engineering net5501.
2805
2806config GEOS
2807	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2808	select GPIOLIB
2809	depends on DMI
2810	help
2811	  This option enables system support for the Traverse Technologies GEOS.
2812
2813config TS5500
2814	bool "Technologic Systems TS-5500 platform support"
2815	depends on MELAN
2816	select CHECK_SIGNATURE
2817	select NEW_LEDS
2818	select LEDS_CLASS
2819	help
2820	  This option enables system support for the Technologic Systems TS-5500.
2821
2822endif # X86_32
2823
2824config AMD_NB
2825	def_bool y
2826	depends on CPU_SUP_AMD && PCI
2827
2828endmenu
2829
2830menu "Binary Emulations"
2831
2832config IA32_EMULATION
2833	bool "IA32 Emulation"
2834	depends on X86_64
2835	select ARCH_WANT_OLD_COMPAT_IPC
2836	select BINFMT_ELF
2837	select COMPAT_OLD_SIGACTION
2838	help
2839	  Include code to run legacy 32-bit programs under a
2840	  64-bit kernel. You should likely turn this on, unless you're
2841	  100% sure that you don't have any 32-bit programs left.
2842
2843config X86_X32_ABI
2844	bool "x32 ABI for 64-bit mode"
2845	depends on X86_64
2846	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2847	# compressed debug sections to x86_x32 properly:
2848	# https://github.com/ClangBuiltLinux/linux/issues/514
2849	# https://github.com/ClangBuiltLinux/linux/issues/1141
2850	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2851	help
2852	  Include code to run binaries for the x32 native 32-bit ABI
2853	  for 64-bit processors.  An x32 process gets access to the
2854	  full 64-bit register file and wide data path while leaving
2855	  pointers at 32 bits for smaller memory footprint.
2856
2857config COMPAT_32
2858	def_bool y
2859	depends on IA32_EMULATION || X86_32
2860	select HAVE_UID16
2861	select OLD_SIGSUSPEND3
2862
2863config COMPAT
2864	def_bool y
2865	depends on IA32_EMULATION || X86_X32_ABI
2866
2867config COMPAT_FOR_U64_ALIGNMENT
2868	def_bool y
2869	depends on COMPAT
2870
2871endmenu
2872
2873config HAVE_ATOMIC_IOMAP
2874	def_bool y
2875	depends on X86_32
2876
2877source "arch/x86/kvm/Kconfig"
2878
2879source "arch/x86/Kconfig.assembler"
2880