xref: /linux/arch/x86/Kconfig (revision cdc8be31cb324a0c52529f192e39a44abcfff513)
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_HAS_PTDUMP
30	select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
31	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
32	select ARCH_SUPPORTS_PER_VMA_LOCK
33	select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
34	select HAVE_ARCH_SOFT_DIRTY
35	select MODULES_USE_ELF_RELA
36	select NEED_DMA_MAP_STATE
37	select SWIOTLB
38	select ARCH_HAS_ELFCORE_COMPAT
39	select ZONE_DMA32
40	select EXECMEM if DYNAMIC_FTRACE
41
42config FORCE_DYNAMIC_FTRACE
43	def_bool y
44	depends on X86_32
45	depends on FUNCTION_TRACER
46	select DYNAMIC_FTRACE
47	help
48	  We keep the static function tracing (!DYNAMIC_FTRACE) around
49	  in order to test the non static function tracing in the
50	  generic code, as other architectures still use it. But we
51	  only need to keep it around for x86_64. No need to keep it
52	  for x86_32. For x86_32, force DYNAMIC_FTRACE.
53#
54# Arch settings
55#
56# ( Note that options that are marked 'if X86_64' could in principle be
57#   ported to 32-bit as well. )
58#
59config X86
60	def_bool y
61	#
62	# Note: keep this list sorted alphabetically
63	#
64	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
65	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
66	select ACPI_HOTPLUG_CPU			if ACPI_PROCESSOR && HOTPLUG_CPU
67	select ARCH_32BIT_OFF_T			if X86_32
68	select ARCH_CLOCKSOURCE_INIT
69	select ARCH_CONFIGURES_CPU_MITIGATIONS
70	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
71	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
72	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
73	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
74	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
75	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
76	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
77	select ARCH_HAS_CACHE_LINE_SIZE
78	select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
79	select ARCH_HAS_CPU_FINALIZE_INIT
80	select ARCH_HAS_CPU_PASID		if IOMMU_SVA
81	select ARCH_HAS_CRC32
82	select ARCH_HAS_CRC64			if X86_64
83	select ARCH_HAS_CRC_T10DIF
84	select ARCH_HAS_CURRENT_STACK_POINTER
85	select ARCH_HAS_DEBUG_VIRTUAL
86	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
87	select ARCH_HAS_DEVMEM_IS_ALLOWED
88	select ARCH_HAS_DMA_OPS			if GART_IOMMU || XEN
89	select ARCH_HAS_EARLY_DEBUG		if KGDB
90	select ARCH_HAS_ELF_RANDOMIZE
91	select ARCH_HAS_EXECMEM_ROX		if X86_64
92	select ARCH_HAS_FAST_MULTIPLIER
93	select ARCH_HAS_FORTIFY_SOURCE
94	select ARCH_HAS_GCOV_PROFILE_ALL
95	select ARCH_HAS_KCOV			if X86_64
96	select ARCH_HAS_KERNEL_FPU_SUPPORT
97	select ARCH_HAS_MEM_ENCRYPT
98	select ARCH_HAS_MEMBARRIER_SYNC_CORE
99	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
100	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
101	select ARCH_HAS_PMEM_API		if X86_64
102	select ARCH_HAS_PREEMPT_LAZY
103	select ARCH_HAS_PTE_DEVMAP		if X86_64
104	select ARCH_HAS_PTE_SPECIAL
105	select ARCH_HAS_HW_PTE_YOUNG
106	select ARCH_HAS_NONLEAF_PMD_YOUNG	if PGTABLE_LEVELS > 2
107	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
108	select ARCH_HAS_COPY_MC			if X86_64
109	select ARCH_HAS_SET_MEMORY
110	select ARCH_HAS_SET_DIRECT_MAP
111	select ARCH_HAS_STRICT_KERNEL_RWX
112	select ARCH_HAS_STRICT_MODULE_RWX
113	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
114	select ARCH_HAS_SYSCALL_WRAPPER
115	select ARCH_HAS_UBSAN
116	select ARCH_HAS_DEBUG_WX
117	select ARCH_HAS_ZONE_DMA_SET if EXPERT
118	select ARCH_HAVE_NMI_SAFE_CMPXCHG
119	select ARCH_HAVE_EXTRA_ELF_NOTES
120	select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
121	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
122	select ARCH_MIGHT_HAVE_PC_PARPORT
123	select ARCH_MIGHT_HAVE_PC_SERIO
124	select ARCH_STACKWALK
125	select ARCH_SUPPORTS_ACPI
126	select ARCH_SUPPORTS_ATOMIC_RMW
127	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
128	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
129	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
130	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
131	select ARCH_SUPPORTS_CFI_CLANG		if X86_64
132	select ARCH_USES_CFI_TRAPS		if X86_64 && CFI_CLANG
133	select ARCH_SUPPORTS_LTO_CLANG
134	select ARCH_SUPPORTS_LTO_CLANG_THIN
135	select ARCH_SUPPORTS_RT
136	select ARCH_SUPPORTS_AUTOFDO_CLANG
137	select ARCH_SUPPORTS_PROPELLER_CLANG    if X86_64
138	select ARCH_USE_BUILTIN_BSWAP
139	select ARCH_USE_CMPXCHG_LOCKREF		if X86_CX8
140	select ARCH_USE_MEMTEST
141	select ARCH_USE_QUEUED_RWLOCKS
142	select ARCH_USE_QUEUED_SPINLOCKS
143	select ARCH_USE_SYM_ANNOTATIONS
144	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
145	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
146	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
147	select ARCH_WANTS_NO_INSTR
148	select ARCH_WANT_GENERAL_HUGETLB
149	select ARCH_WANT_HUGE_PMD_SHARE
150	select ARCH_WANT_LD_ORPHAN_WARN
151	select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP	if X86_64
152	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP	if X86_64
153	select ARCH_WANT_HUGETLB_VMEMMAP_PREINIT if X86_64
154	select ARCH_WANTS_THP_SWAP		if X86_64
155	select ARCH_HAS_PARANOID_L1D_FLUSH
156	select ARCH_WANT_IRQS_OFF_ACTIVATE_MM
157	select BUILDTIME_TABLE_SORT
158	select CLKEVT_I8253
159	select CLOCKSOURCE_WATCHDOG
160	# Word-size accesses may read uninitialized data past the trailing \0
161	# in strings and cause false KMSAN reports.
162	select DCACHE_WORD_ACCESS		if !KMSAN
163	select DYNAMIC_SIGFRAME
164	select EDAC_ATOMIC_SCRUB
165	select EDAC_SUPPORT
166	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
167	select GENERIC_CLOCKEVENTS_BROADCAST_IDLE	if GENERIC_CLOCKEVENTS_BROADCAST
168	select GENERIC_CLOCKEVENTS_MIN_ADJUST
169	select GENERIC_CMOS_UPDATE
170	select GENERIC_CPU_AUTOPROBE
171	select GENERIC_CPU_DEVICES
172	select GENERIC_CPU_VULNERABILITIES
173	select GENERIC_EARLY_IOREMAP
174	select GENERIC_ENTRY
175	select GENERIC_IOMAP
176	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
177	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
178	select GENERIC_IRQ_MIGRATION		if SMP
179	select GENERIC_IRQ_PROBE
180	select GENERIC_IRQ_RESERVATION_MODE
181	select GENERIC_IRQ_SHOW
182	select GENERIC_PENDING_IRQ		if SMP
183	select GENERIC_SMP_IDLE_THREAD
184	select GENERIC_TIME_VSYSCALL
185	select GENERIC_GETTIMEOFDAY
186	select GENERIC_VDSO_DATA_STORE
187	select GENERIC_VDSO_TIME_NS
188	select GENERIC_VDSO_OVERFLOW_PROTECT
189	select GUP_GET_PXX_LOW_HIGH		if X86_PAE
190	select HARDIRQS_SW_RESEND
191	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
192	select HAS_IOPORT
193	select HAVE_ACPI_APEI			if ACPI
194	select HAVE_ACPI_APEI_NMI		if ACPI
195	select HAVE_ALIGNED_STRUCT_PAGE
196	select HAVE_ARCH_AUDITSYSCALL
197	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
198	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
199	select HAVE_ARCH_JUMP_LABEL
200	select HAVE_ARCH_JUMP_LABEL_RELATIVE
201	select HAVE_ARCH_KASAN			if X86_64
202	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
203	select HAVE_ARCH_KFENCE
204	select HAVE_ARCH_KMSAN			if X86_64
205	select HAVE_ARCH_KGDB
206	select HAVE_ARCH_MMAP_RND_BITS		if MMU
207	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
208	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
209	select HAVE_ARCH_PREL32_RELOCATIONS
210	select HAVE_ARCH_SECCOMP_FILTER
211	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
212	select HAVE_ARCH_STACKLEAK
213	select HAVE_ARCH_TRACEHOOK
214	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
215	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
216	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
217	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
218	select HAVE_ARCH_VMAP_STACK		if X86_64
219	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
220	select HAVE_ARCH_WITHIN_STACK_FRAMES
221	select HAVE_ASM_MODVERSIONS
222	select HAVE_CMPXCHG_DOUBLE
223	select HAVE_CMPXCHG_LOCAL
224	select HAVE_CONTEXT_TRACKING_USER		if X86_64
225	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
226	select HAVE_C_RECORDMCOUNT
227	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
228	select HAVE_OBJTOOL_NOP_MCOUNT		if HAVE_OBJTOOL_MCOUNT
229	select HAVE_BUILDTIME_MCOUNT_SORT
230	select HAVE_DEBUG_KMEMLEAK
231	select HAVE_DMA_CONTIGUOUS
232	select HAVE_DYNAMIC_FTRACE
233	select HAVE_DYNAMIC_FTRACE_WITH_REGS
234	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
235	select HAVE_FTRACE_REGS_HAVING_PT_REGS	if X86_64
236	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
237	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
238	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
239	select HAVE_EBPF_JIT
240	select HAVE_EFFICIENT_UNALIGNED_ACCESS
241	select HAVE_EISA			if X86_32
242	select HAVE_EXIT_THREAD
243	select HAVE_GUP_FAST
244	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
245	select HAVE_FTRACE_GRAPH_FUNC		if HAVE_FUNCTION_GRAPH_TRACER
246	select HAVE_FTRACE_MCOUNT_RECORD
247	select HAVE_FUNCTION_GRAPH_FREGS	if HAVE_FUNCTION_GRAPH_TRACER
248	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
249	select HAVE_FUNCTION_TRACER
250	select HAVE_GCC_PLUGINS
251	select HAVE_HW_BREAKPOINT
252	select HAVE_IOREMAP_PROT
253	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
254	select HAVE_IRQ_TIME_ACCOUNTING
255	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
256	select HAVE_KERNEL_BZIP2
257	select HAVE_KERNEL_GZIP
258	select HAVE_KERNEL_LZ4
259	select HAVE_KERNEL_LZMA
260	select HAVE_KERNEL_LZO
261	select HAVE_KERNEL_XZ
262	select HAVE_KERNEL_ZSTD
263	select HAVE_KPROBES
264	select HAVE_KPROBES_ON_FTRACE
265	select HAVE_FUNCTION_ERROR_INJECTION
266	select HAVE_KRETPROBES
267	select HAVE_RETHOOK
268	select HAVE_LIVEPATCH			if X86_64
269	select HAVE_MIXED_BREAKPOINTS_REGS
270	select HAVE_MOD_ARCH_SPECIFIC
271	select HAVE_MOVE_PMD
272	select HAVE_MOVE_PUD
273	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
274	select HAVE_NMI
275	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
276	select HAVE_OBJTOOL			if X86_64
277	select HAVE_OPTPROBES
278	select HAVE_PAGE_SIZE_4KB
279	select HAVE_PCSPKR_PLATFORM
280	select HAVE_PERF_EVENTS
281	select HAVE_PERF_EVENTS_NMI
282	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
283	select HAVE_PCI
284	select HAVE_PERF_REGS
285	select HAVE_PERF_USER_STACK_DUMP
286	select MMU_GATHER_RCU_TABLE_FREE
287	select MMU_GATHER_MERGE_VMAS
288	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
289	select HAVE_REGS_AND_STACK_ACCESS_API
290	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
291	select HAVE_FUNCTION_ARG_ACCESS_API
292	select HAVE_SETUP_PER_CPU_AREA
293	select HAVE_SOFTIRQ_ON_OWN_STACK
294	select HAVE_STACKPROTECTOR
295	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
296	select HAVE_STATIC_CALL
297	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
298	select HAVE_PREEMPT_DYNAMIC_CALL
299	select HAVE_RSEQ
300	select HAVE_RUST			if X86_64
301	select HAVE_SYSCALL_TRACEPOINTS
302	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
303	select HAVE_UNSTABLE_SCHED_CLOCK
304	select HAVE_USER_RETURN_NOTIFIER
305	select HAVE_GENERIC_VDSO
306	select VDSO_GETRANDOM			if X86_64
307	select HOTPLUG_PARALLEL			if SMP && X86_64
308	select HOTPLUG_SMT			if SMP
309	select HOTPLUG_SPLIT_STARTUP		if SMP && X86_32
310	select IRQ_FORCED_THREADING
311	select LOCK_MM_AND_FIND_VMA
312	select NEED_PER_CPU_EMBED_FIRST_CHUNK
313	select NEED_PER_CPU_PAGE_FIRST_CHUNK
314	select NEED_SG_DMA_LENGTH
315	select NUMA_MEMBLKS			if NUMA
316	select PCI_DOMAINS			if PCI
317	select PCI_LOCKLESS_CONFIG		if PCI
318	select PERF_EVENTS
319	select RTC_LIB
320	select RTC_MC146818_LIB
321	select SPARSE_IRQ
322	select SYSCTL_EXCEPTION_TRACE
323	select THREAD_INFO_IN_TASK
324	select TRACE_IRQFLAGS_SUPPORT
325	select TRACE_IRQFLAGS_NMI_SUPPORT
326	select USER_STACKTRACE_SUPPORT
327	select HAVE_ARCH_KCSAN			if X86_64
328	select PROC_PID_ARCH_STATUS		if PROC_FS
329	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
330	select FUNCTION_ALIGNMENT_16B		if X86_64 || X86_ALIGNMENT_16
331	select FUNCTION_ALIGNMENT_4B
332	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
333	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
334	select ARCH_SUPPORTS_PT_RECLAIM		if X86_64
335
336config INSTRUCTION_DECODER
337	def_bool y
338	depends on KPROBES || PERF_EVENTS || UPROBES
339
340config OUTPUT_FORMAT
341	string
342	default "elf32-i386" if X86_32
343	default "elf64-x86-64" if X86_64
344
345config LOCKDEP_SUPPORT
346	def_bool y
347
348config STACKTRACE_SUPPORT
349	def_bool y
350
351config MMU
352	def_bool y
353
354config ARCH_MMAP_RND_BITS_MIN
355	default 28 if 64BIT
356	default 8
357
358config ARCH_MMAP_RND_BITS_MAX
359	default 32 if 64BIT
360	default 16
361
362config ARCH_MMAP_RND_COMPAT_BITS_MIN
363	default 8
364
365config ARCH_MMAP_RND_COMPAT_BITS_MAX
366	default 16
367
368config SBUS
369	bool
370
371config GENERIC_ISA_DMA
372	def_bool y
373	depends on ISA_DMA_API
374
375config GENERIC_CSUM
376	bool
377	default y if KMSAN || KASAN
378
379config GENERIC_BUG
380	def_bool y
381	depends on BUG
382	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
383
384config GENERIC_BUG_RELATIVE_POINTERS
385	bool
386
387config ARCH_MAY_HAVE_PC_FDC
388	def_bool y
389	depends on ISA_DMA_API
390
391config GENERIC_CALIBRATE_DELAY
392	def_bool y
393
394config ARCH_HAS_CPU_RELAX
395	def_bool y
396
397config ARCH_HIBERNATION_POSSIBLE
398	def_bool y
399
400config ARCH_SUSPEND_POSSIBLE
401	def_bool y
402
403config AUDIT_ARCH
404	def_bool y if X86_64
405
406config KASAN_SHADOW_OFFSET
407	hex
408	depends on KASAN
409	default 0xdffffc0000000000
410
411config HAVE_INTEL_TXT
412	def_bool y
413	depends on INTEL_IOMMU && ACPI
414
415config X86_64_SMP
416	def_bool y
417	depends on X86_64 && SMP
418
419config ARCH_SUPPORTS_UPROBES
420	def_bool y
421
422config FIX_EARLYCON_MEM
423	def_bool y
424
425config DYNAMIC_PHYSICAL_MASK
426	bool
427
428config PGTABLE_LEVELS
429	int
430	default 5 if X86_5LEVEL
431	default 4 if X86_64
432	default 3 if X86_PAE
433	default 2
434
435menu "Processor type and features"
436
437config SMP
438	bool "Symmetric multi-processing support"
439	help
440	  This enables support for systems with more than one CPU. If you have
441	  a system with only one CPU, say N. If you have a system with more
442	  than one CPU, say Y.
443
444	  If you say N here, the kernel will run on uni- and multiprocessor
445	  machines, but will use only one CPU of a multiprocessor machine. If
446	  you say Y here, the kernel will run on many, but not all,
447	  uniprocessor machines. On a uniprocessor machine, the kernel
448	  will run faster if you say N here.
449
450	  Note that if you say Y here and choose architecture "586" or
451	  "Pentium" under "Processor family", the kernel will not work on 486
452	  architectures. Similarly, multiprocessor kernels for the "PPro"
453	  architecture may not work on all Pentium based boards.
454
455	  People using multiprocessor machines who say Y here should also say
456	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
457	  Management" code will be disabled if you say Y here.
458
459	  See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
460	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
461	  <http://www.tldp.org/docs.html#howto>.
462
463	  If you don't know what to do here, say N.
464
465config X86_X2APIC
466	bool "x2APIC interrupt controller architecture support"
467	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
468	default y
469	help
470	  x2APIC is an interrupt controller architecture, a component of which
471	  (the local APIC) is present in the CPU. It allows faster access to
472	  the local APIC and supports a larger number of CPUs in the system
473	  than the predecessors.
474
475	  x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs
476	  in 2019, but it can be disabled by the BIOS. It is also frequently
477	  emulated in virtual machines, even when the host CPU does not support
478	  it. Support in the CPU can be checked by executing
479		grep x2apic /proc/cpuinfo
480
481	  If this configuration option is disabled, the kernel will boot with
482	  very reduced functionality and performance on some platforms that
483	  have x2APIC enabled. On the other hand, on hardware that does not
484	  support x2APIC, a kernel with this option enabled will just fallback
485	  to older APIC implementations.
486
487	  If in doubt, say Y.
488
489config X86_POSTED_MSI
490	bool "Enable MSI and MSI-x delivery by posted interrupts"
491	depends on X86_64 && IRQ_REMAP
492	help
493	  This enables MSIs that are under interrupt remapping to be delivered as
494	  posted interrupts to the host kernel. Interrupt throughput can
495	  potentially be improved by coalescing CPU notifications during high
496	  frequency bursts.
497
498	  If you don't know what to do here, say N.
499
500config X86_MPPARSE
501	bool "Enable MPS table" if ACPI
502	default y
503	depends on X86_LOCAL_APIC
504	help
505	  For old smp systems that do not have proper acpi support. Newer systems
506	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
507
508config X86_CPU_RESCTRL
509	bool "x86 CPU resource control support"
510	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
511	select KERNFS
512	select PROC_CPU_RESCTRL		if PROC_FS
513	select RESCTRL_FS_PSEUDO_LOCK
514	help
515	  Enable x86 CPU resource control support.
516
517	  Provide support for the allocation and monitoring of system resources
518	  usage by the CPU.
519
520	  Intel calls this Intel Resource Director Technology
521	  (Intel(R) RDT). More information about RDT can be found in the
522	  Intel x86 Architecture Software Developer Manual.
523
524	  AMD calls this AMD Platform Quality of Service (AMD QoS).
525	  More information about AMD QoS can be found in the AMD64 Technology
526	  Platform Quality of Service Extensions manual.
527
528	  Say N if unsure.
529
530config RESCTRL_FS_PSEUDO_LOCK
531	bool
532	help
533	  Software mechanism to pin data in a cache portion using
534	  micro-architecture specific knowledge.
535
536config X86_FRED
537	bool "Flexible Return and Event Delivery"
538	depends on X86_64
539	help
540	  When enabled, try to use Flexible Return and Event Delivery
541	  instead of the legacy SYSCALL/SYSENTER/IDT architecture for
542	  ring transitions and exception/interrupt handling if the
543	  system supports it.
544
545config X86_EXTENDED_PLATFORM
546	bool "Support for extended (non-PC) x86 platforms"
547	default y
548	help
549	  If you disable this option then the kernel will only support
550	  standard PC platforms. (which covers the vast majority of
551	  systems out there.)
552
553	  If you enable this option then you'll be able to select support
554	  for the following non-PC x86 platforms, depending on the value of
555	  CONFIG_64BIT.
556
557	  32-bit platforms (CONFIG_64BIT=n):
558		Goldfish (mostly Android emulator)
559		Intel CE media processor (CE4100) SoC
560		Intel Quark
561		RDC R-321x SoC
562
563	  64-bit platforms (CONFIG_64BIT=y):
564		Numascale NumaChip
565		ScaleMP vSMP
566		SGI Ultraviolet
567		Merrifield/Moorefield MID devices
568		Goldfish (mostly Android emulator)
569
570	  If you have one of these systems, or if you want to build a
571	  generic distribution kernel, say Y here - otherwise say N.
572
573# This is an alphabetically sorted list of 64 bit extended platforms
574# Please maintain the alphabetic order if and when there are additions
575config X86_NUMACHIP
576	bool "Numascale NumaChip"
577	depends on X86_64
578	depends on X86_EXTENDED_PLATFORM
579	depends on NUMA
580	depends on SMP
581	depends on X86_X2APIC
582	depends on PCI_MMCONFIG
583	help
584	  Adds support for Numascale NumaChip large-SMP systems. Needed to
585	  enable more than ~168 cores.
586	  If you don't have one of these, you should say N here.
587
588config X86_VSMP
589	bool "ScaleMP vSMP"
590	select HYPERVISOR_GUEST
591	select PARAVIRT
592	depends on X86_64 && PCI
593	depends on X86_EXTENDED_PLATFORM
594	depends on SMP
595	help
596	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
597	  supposed to run on these EM64T-based machines.  Only choose this option
598	  if you have one of these machines.
599
600config X86_UV
601	bool "SGI Ultraviolet"
602	depends on X86_64
603	depends on X86_EXTENDED_PLATFORM
604	depends on NUMA
605	depends on EFI
606	depends on KEXEC_CORE
607	depends on X86_X2APIC
608	depends on PCI
609	help
610	  This option is needed in order to support SGI Ultraviolet systems.
611	  If you don't have one of these, you should say N here.
612
613config X86_INTEL_MID
614	bool "Intel Z34xx/Z35xx MID platform support"
615	depends on X86_EXTENDED_PLATFORM
616	depends on X86_PLATFORM_DEVICES
617	depends on PCI
618	depends on X86_64 || (EXPERT && PCI_GOANY)
619	depends on X86_IO_APIC
620	select I2C
621	select DW_APB_TIMER
622	select INTEL_SCU_PCI
623	help
624	  Select to build a kernel capable of supporting 64-bit Intel MID
625	  (Mobile Internet Device) platform systems which do not have
626	  the PCI legacy interfaces.
627
628	  The only supported devices are the 22nm Merrified (Z34xx)
629	  and Moorefield (Z35xx) SoC used in the Intel Edison board and
630	  a small number of Android devices such as the Asus Zenfone 2,
631	  Asus FonePad 8 and Dell Venue 7.
632
633	  If you are building for a PC class system or non-MID tablet
634	  SoCs like Bay Trail (Z36xx/Z37xx), 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_GOLDFISH
640	bool "Goldfish (Virtual Platform)"
641	depends on X86_EXTENDED_PLATFORM
642	help
643	  Enable support for the Goldfish virtual platform used primarily
644	  for Android development. Unless you are building for the Android
645	  Goldfish emulator say N here.
646
647# Following is an alphabetically sorted list of 32 bit extended platforms
648# Please maintain the alphabetic order if and when there are additions
649
650config X86_INTEL_CE
651	bool "CE4100 TV platform"
652	depends on PCI
653	depends on PCI_GODIRECT
654	depends on X86_IO_APIC
655	depends on X86_32
656	depends on X86_EXTENDED_PLATFORM
657	select X86_REBOOTFIXUPS
658	select OF
659	select OF_EARLY_FLATTREE
660	help
661	  Select for the Intel CE media processor (CE4100) SOC.
662	  This option compiles in support for the CE4100 SOC for settop
663	  boxes and media devices.
664
665config X86_INTEL_QUARK
666	bool "Intel Quark platform support"
667	depends on X86_32
668	depends on X86_EXTENDED_PLATFORM
669	depends on X86_PLATFORM_DEVICES
670	depends on X86_TSC
671	depends on PCI
672	depends on PCI_GOANY
673	depends on X86_IO_APIC
674	select IOSF_MBI
675	select INTEL_IMR
676	select COMMON_CLK
677	help
678	  Select to include support for Quark X1000 SoC.
679	  Say Y here if you have a Quark based system such as the Arduino
680	  compatible Intel Galileo.
681
682config X86_RDC321X
683	bool "RDC R-321x SoC"
684	depends on X86_32
685	depends on X86_EXTENDED_PLATFORM
686	select M486
687	select X86_REBOOTFIXUPS
688	help
689	  This option is needed for RDC R-321x system-on-chip, also known
690	  as R-8610-(G).
691	  If you don't have one of these chips, you should say N here.
692
693config X86_INTEL_LPSS
694	bool "Intel Low Power Subsystem Support"
695	depends on X86 && ACPI && PCI
696	select COMMON_CLK
697	select PINCTRL
698	select IOSF_MBI
699	help
700	  Select to build support for Intel Low Power Subsystem such as
701	  found on Intel Lynxpoint PCH. Selecting this option enables
702	  things like clock tree (common clock framework) and pincontrol
703	  which are needed by the LPSS peripheral drivers.
704
705config X86_AMD_PLATFORM_DEVICE
706	bool "AMD ACPI2Platform devices support"
707	depends on ACPI
708	select COMMON_CLK
709	select PINCTRL
710	help
711	  Select to interpret AMD specific ACPI device to platform device
712	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
713	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
714	  implemented under PINCTRL subsystem.
715
716config IOSF_MBI
717	tristate "Intel SoC IOSF Sideband support for SoC platforms"
718	depends on PCI
719	help
720	  This option enables sideband register access support for Intel SoC
721	  platforms. On these platforms the IOSF sideband is used in lieu of
722	  MSR's for some register accesses, mostly but not limited to thermal
723	  and power. Drivers may query the availability of this device to
724	  determine if they need the sideband in order to work on these
725	  platforms. The sideband is available on the following SoC products.
726	  This list is not meant to be exclusive.
727	   - BayTrail
728	   - Braswell
729	   - Quark
730
731	  You should say Y if you are running a kernel on one of these SoC's.
732
733config IOSF_MBI_DEBUG
734	bool "Enable IOSF sideband access through debugfs"
735	depends on IOSF_MBI && DEBUG_FS
736	help
737	  Select this option to expose the IOSF sideband access registers (MCR,
738	  MDR, MCRX) through debugfs to write and read register information from
739	  different units on the SoC. This is most useful for obtaining device
740	  state information for debug and analysis. As this is a general access
741	  mechanism, users of this option would have specific knowledge of the
742	  device they want to access.
743
744	  If you don't require the option or are in doubt, say N.
745
746config X86_SUPPORTS_MEMORY_FAILURE
747	def_bool y
748	# MCE code calls memory_failure():
749	depends on X86_MCE
750	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
751	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
752	depends on X86_64 || !SPARSEMEM
753	select ARCH_SUPPORTS_MEMORY_FAILURE
754
755config X86_32_IRIS
756	tristate "Eurobraille/Iris poweroff module"
757	depends on X86_32
758	help
759	  The Iris machines from EuroBraille do not have APM or ACPI support
760	  to shut themselves down properly.  A special I/O sequence is
761	  needed to do so, which is what this module does at
762	  kernel shutdown.
763
764	  This is only for Iris machines from EuroBraille.
765
766	  If unused, say N.
767
768config SCHED_OMIT_FRAME_POINTER
769	def_bool y
770	prompt "Single-depth WCHAN output"
771	depends on X86
772	help
773	  Calculate simpler /proc/<PID>/wchan values. If this option
774	  is disabled then wchan values will recurse back to the
775	  caller function. This provides more accurate wchan values,
776	  at the expense of slightly more scheduling overhead.
777
778	  If in doubt, say "Y".
779
780menuconfig HYPERVISOR_GUEST
781	bool "Linux guest support"
782	help
783	  Say Y here to enable options for running Linux under various hyper-
784	  visors. This option enables basic hypervisor detection and platform
785	  setup.
786
787	  If you say N, all options in this submenu will be skipped and
788	  disabled, and Linux guest support won't be built in.
789
790if HYPERVISOR_GUEST
791
792config PARAVIRT
793	bool "Enable paravirtualization code"
794	depends on HAVE_STATIC_CALL
795	help
796	  This changes the kernel so it can modify itself when it is run
797	  under a hypervisor, potentially improving performance significantly
798	  over full virtualization.  However, when run without a hypervisor
799	  the kernel is theoretically slower and slightly larger.
800
801config PARAVIRT_XXL
802	bool
803
804config PARAVIRT_DEBUG
805	bool "paravirt-ops debugging"
806	depends on PARAVIRT && DEBUG_KERNEL
807	help
808	  Enable to debug paravirt_ops internals.  Specifically, BUG if
809	  a paravirt_op is missing when it is called.
810
811config PARAVIRT_SPINLOCKS
812	bool "Paravirtualization layer for spinlocks"
813	depends on PARAVIRT && SMP
814	help
815	  Paravirtualized spinlocks allow a pvops backend to replace the
816	  spinlock implementation with something virtualization-friendly
817	  (for example, block the virtual CPU rather than spinning).
818
819	  It has a minimal impact on native kernels and gives a nice performance
820	  benefit on paravirtualized KVM / Xen kernels.
821
822	  If you are unsure how to answer this question, answer Y.
823
824config X86_HV_CALLBACK_VECTOR
825	def_bool n
826
827source "arch/x86/xen/Kconfig"
828
829config KVM_GUEST
830	bool "KVM Guest support (including kvmclock)"
831	depends on PARAVIRT
832	select PARAVIRT_CLOCK
833	select ARCH_CPUIDLE_HALTPOLL
834	select X86_HV_CALLBACK_VECTOR
835	default y
836	help
837	  This option enables various optimizations for running under the KVM
838	  hypervisor. It includes a paravirtualized clock, so that instead
839	  of relying on a PIT (or probably other) emulation by the
840	  underlying device model, the host provides the guest with
841	  timing infrastructure such as time of day, and system time
842
843config ARCH_CPUIDLE_HALTPOLL
844	def_bool n
845	prompt "Disable host haltpoll when loading haltpoll driver"
846	help
847	  If virtualized under KVM, disable host haltpoll.
848
849config PVH
850	bool "Support for running PVH guests"
851	help
852	  This option enables the PVH entry point for guest virtual machines
853	  as specified in the x86/HVM direct boot ABI.
854
855config PARAVIRT_TIME_ACCOUNTING
856	bool "Paravirtual steal time accounting"
857	depends on PARAVIRT
858	help
859	  Select this option to enable fine granularity task steal time
860	  accounting. Time spent executing other tasks in parallel with
861	  the current vCPU is discounted from the vCPU power. To account for
862	  that, there can be a small performance impact.
863
864	  If in doubt, say N here.
865
866config PARAVIRT_CLOCK
867	bool
868
869config JAILHOUSE_GUEST
870	bool "Jailhouse non-root cell support"
871	depends on X86_64 && PCI
872	select X86_PM_TIMER
873	help
874	  This option allows to run Linux as guest in a Jailhouse non-root
875	  cell. You can leave this option disabled if you only want to start
876	  Jailhouse and run Linux afterwards in the root cell.
877
878config ACRN_GUEST
879	bool "ACRN Guest support"
880	depends on X86_64
881	select X86_HV_CALLBACK_VECTOR
882	help
883	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
884	  a flexible, lightweight reference open-source hypervisor, built with
885	  real-time and safety-criticality in mind. It is built for embedded
886	  IOT with small footprint and real-time features. More details can be
887	  found in https://projectacrn.org/.
888
889config INTEL_TDX_GUEST
890	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
891	depends on X86_64 && CPU_SUP_INTEL
892	depends on X86_X2APIC
893	depends on EFI_STUB
894	depends on PARAVIRT
895	select ARCH_HAS_CC_PLATFORM
896	select X86_MEM_ENCRYPT
897	select X86_MCE
898	select UNACCEPTED_MEMORY
899	help
900	  Support running as a guest under Intel TDX.  Without this support,
901	  the guest kernel can not boot or run under TDX.
902	  TDX includes memory encryption and integrity capabilities
903	  which protect the confidentiality and integrity of guest
904	  memory contents and CPU state. TDX guests are protected from
905	  some attacks from the VMM.
906
907endif # HYPERVISOR_GUEST
908
909source "arch/x86/Kconfig.cpu"
910
911config HPET_TIMER
912	def_bool X86_64
913	prompt "HPET Timer Support" if X86_32
914	help
915	  Use the IA-PC HPET (High Precision Event Timer) to manage
916	  time in preference to the PIT and RTC, if a HPET is
917	  present.
918	  HPET is the next generation timer replacing legacy 8254s.
919	  The HPET provides a stable time base on SMP
920	  systems, unlike the TSC, but it is more expensive to access,
921	  as it is off-chip.  The interface used is documented
922	  in the HPET spec, revision 1.
923
924	  You can safely choose Y here.  However, HPET will only be
925	  activated if the platform and the BIOS support this feature.
926	  Otherwise the 8254 will be used for timing services.
927
928	  Choose N to continue using the legacy 8254 timer.
929
930config HPET_EMULATE_RTC
931	def_bool y
932	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
933
934# Mark as expert because too many people got it wrong.
935# The code disables itself when not needed.
936config DMI
937	default y
938	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
939	bool "Enable DMI scanning" if EXPERT
940	help
941	  Enabled scanning of DMI to identify machine quirks. Say Y
942	  here unless you have verified that your setup is not
943	  affected by entries in the DMI blacklist. Required by PNP
944	  BIOS code.
945
946config GART_IOMMU
947	bool "Old AMD GART IOMMU support"
948	select IOMMU_HELPER
949	select SWIOTLB
950	depends on X86_64 && PCI && AMD_NB
951	help
952	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
953	  GART based hardware IOMMUs.
954
955	  The GART supports full DMA access for devices with 32-bit access
956	  limitations, on systems with more than 3 GB. This is usually needed
957	  for USB, sound, many IDE/SATA chipsets and some other devices.
958
959	  Newer systems typically have a modern AMD IOMMU, supported via
960	  the CONFIG_AMD_IOMMU=y config option.
961
962	  In normal configurations this driver is only active when needed:
963	  there's more than 3 GB of memory and the system contains a
964	  32-bit limited device.
965
966	  If unsure, say Y.
967
968config BOOT_VESA_SUPPORT
969	bool
970	help
971	  If true, at least one selected framebuffer driver can take advantage
972	  of VESA video modes set at an early boot stage via the vga= parameter.
973
974config MAXSMP
975	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
976	depends on X86_64 && SMP && DEBUG_KERNEL
977	select CPUMASK_OFFSTACK
978	help
979	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
980	  If unsure, say N.
981
982#
983# The maximum number of CPUs supported:
984#
985# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
986# and which can be configured interactively in the
987# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
988#
989# The ranges are different on 32-bit and 64-bit kernels, depending on
990# hardware capabilities and scalability features of the kernel.
991#
992# ( If MAXSMP is enabled we just use the highest possible value and disable
993#   interactive configuration. )
994#
995
996config NR_CPUS_RANGE_BEGIN
997	int
998	default NR_CPUS_RANGE_END if MAXSMP
999	default    1 if !SMP
1000	default    2
1001
1002config NR_CPUS_RANGE_END
1003	int
1004	depends on X86_32
1005	default    8 if  SMP
1006	default    1 if !SMP
1007
1008config NR_CPUS_RANGE_END
1009	int
1010	depends on X86_64
1011	default 8192 if  SMP && CPUMASK_OFFSTACK
1012	default  512 if  SMP && !CPUMASK_OFFSTACK
1013	default    1 if !SMP
1014
1015config NR_CPUS_DEFAULT
1016	int
1017	depends on X86_32
1018	default    8 if  SMP
1019	default    1 if !SMP
1020
1021config NR_CPUS_DEFAULT
1022	int
1023	depends on X86_64
1024	default 8192 if  MAXSMP
1025	default   64 if  SMP
1026	default    1 if !SMP
1027
1028config NR_CPUS
1029	int "Maximum number of CPUs" if SMP && !MAXSMP
1030	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1031	default NR_CPUS_DEFAULT
1032	help
1033	  This allows you to specify the maximum number of CPUs which this
1034	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1035	  supported value is 8192, otherwise the maximum value is 512.  The
1036	  minimum value which makes sense is 2.
1037
1038	  This is purely to save memory: each supported CPU adds about 8KB
1039	  to the kernel image.
1040
1041config SCHED_CLUSTER
1042	bool "Cluster scheduler support"
1043	depends on SMP
1044	default y
1045	help
1046	  Cluster scheduler support improves the CPU scheduler's decision
1047	  making when dealing with machines that have clusters of CPUs.
1048	  Cluster usually means a couple of CPUs which are placed closely
1049	  by sharing mid-level caches, last-level cache tags or internal
1050	  busses.
1051
1052config SCHED_SMT
1053	def_bool y if SMP
1054
1055config SCHED_MC
1056	def_bool y
1057	prompt "Multi-core scheduler support"
1058	depends on SMP
1059	help
1060	  Multi-core scheduler support improves the CPU scheduler's decision
1061	  making when dealing with multi-core CPU chips at a cost of slightly
1062	  increased overhead in some places. If unsure say N here.
1063
1064config SCHED_MC_PRIO
1065	bool "CPU core priorities scheduler support"
1066	depends on SCHED_MC
1067	select X86_INTEL_PSTATE if CPU_SUP_INTEL
1068	select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
1069	select CPU_FREQ
1070	default y
1071	help
1072	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1073	  core ordering determined at manufacturing time, which allows
1074	  certain cores to reach higher turbo frequencies (when running
1075	  single threaded workloads) than others.
1076
1077	  Enabling this kernel feature teaches the scheduler about
1078	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1079	  scheduler's CPU selection logic accordingly, so that higher
1080	  overall system performance can be achieved.
1081
1082	  This feature will have no effect on CPUs without this feature.
1083
1084	  If unsure say Y here.
1085
1086config UP_LATE_INIT
1087	def_bool y
1088	depends on !SMP && X86_LOCAL_APIC
1089
1090config X86_UP_APIC
1091	bool "Local APIC support on uniprocessors" if !PCI_MSI
1092	default PCI_MSI
1093	depends on X86_32 && !SMP
1094	help
1095	  A local APIC (Advanced Programmable Interrupt Controller) is an
1096	  integrated interrupt controller in the CPU. If you have a single-CPU
1097	  system which has a processor with a local APIC, you can say Y here to
1098	  enable and use it. If you say Y here even though your machine doesn't
1099	  have a local APIC, then the kernel will still run with no slowdown at
1100	  all. The local APIC supports CPU-generated self-interrupts (timer,
1101	  performance counters), and the NMI watchdog which detects hard
1102	  lockups.
1103
1104config X86_UP_IOAPIC
1105	bool "IO-APIC support on uniprocessors"
1106	depends on X86_UP_APIC
1107	help
1108	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1109	  SMP-capable replacement for PC-style interrupt controllers. Most
1110	  SMP systems and many recent uniprocessor systems have one.
1111
1112	  If you have a single-CPU system with an IO-APIC, you can say Y here
1113	  to use it. If you say Y here even though your machine doesn't have
1114	  an IO-APIC, then the kernel will still run with no slowdown at all.
1115
1116config X86_LOCAL_APIC
1117	def_bool y
1118	depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI
1119	select IRQ_DOMAIN_HIERARCHY
1120
1121config ACPI_MADT_WAKEUP
1122	def_bool y
1123	depends on X86_64
1124	depends on ACPI
1125	depends on SMP
1126	depends on X86_LOCAL_APIC
1127
1128config X86_IO_APIC
1129	def_bool y
1130	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1131
1132config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1133	bool "Reroute for broken boot IRQs"
1134	depends on X86_IO_APIC
1135	help
1136	  This option enables a workaround that fixes a source of
1137	  spurious interrupts. This is recommended when threaded
1138	  interrupt handling is used on systems where the generation of
1139	  superfluous "boot interrupts" cannot be disabled.
1140
1141	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1142	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1143	  kernel does during interrupt handling). On chipsets where this
1144	  boot IRQ generation cannot be disabled, this workaround keeps
1145	  the original IRQ line masked so that only the equivalent "boot
1146	  IRQ" is delivered to the CPUs. The workaround also tells the
1147	  kernel to set up the IRQ handler on the boot IRQ line. In this
1148	  way only one interrupt is delivered to the kernel. Otherwise
1149	  the spurious second interrupt may cause the kernel to bring
1150	  down (vital) interrupt lines.
1151
1152	  Only affects "broken" chipsets. Interrupt sharing may be
1153	  increased on these systems.
1154
1155config X86_MCE
1156	bool "Machine Check / overheating reporting"
1157	select GENERIC_ALLOCATOR
1158	default y
1159	help
1160	  Machine Check support allows the processor to notify the
1161	  kernel if it detects a problem (e.g. overheating, data corruption).
1162	  The action the kernel takes depends on the severity of the problem,
1163	  ranging from warning messages to halting the machine.
1164
1165config X86_MCELOG_LEGACY
1166	bool "Support for deprecated /dev/mcelog character device"
1167	depends on X86_MCE
1168	help
1169	  Enable support for /dev/mcelog which is needed by the old mcelog
1170	  userspace logging daemon. Consider switching to the new generation
1171	  rasdaemon solution.
1172
1173config X86_MCE_INTEL
1174	def_bool y
1175	prompt "Intel MCE features"
1176	depends on X86_MCE && X86_LOCAL_APIC
1177	help
1178	  Additional support for intel specific MCE features such as
1179	  the thermal monitor.
1180
1181config X86_MCE_AMD
1182	def_bool y
1183	prompt "AMD MCE features"
1184	depends on X86_MCE && X86_LOCAL_APIC
1185	help
1186	  Additional support for AMD specific MCE features such as
1187	  the DRAM Error Threshold.
1188
1189config X86_ANCIENT_MCE
1190	bool "Support for old Pentium 5 / WinChip machine checks"
1191	depends on X86_32 && X86_MCE
1192	help
1193	  Include support for machine check handling on old Pentium 5 or WinChip
1194	  systems. These typically need to be enabled explicitly on the command
1195	  line.
1196
1197config X86_MCE_THRESHOLD
1198	depends on X86_MCE_AMD || X86_MCE_INTEL
1199	def_bool y
1200
1201config X86_MCE_INJECT
1202	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1203	tristate "Machine check injector support"
1204	help
1205	  Provide support for injecting machine checks for testing purposes.
1206	  If you don't know what a machine check is and you don't do kernel
1207	  QA it is safe to say n.
1208
1209source "arch/x86/events/Kconfig"
1210
1211config X86_LEGACY_VM86
1212	bool "Legacy VM86 support"
1213	depends on X86_32
1214	help
1215	  This option allows user programs to put the CPU into V8086
1216	  mode, which is an 80286-era approximation of 16-bit real mode.
1217
1218	  Some very old versions of X and/or vbetool require this option
1219	  for user mode setting.  Similarly, DOSEMU will use it if
1220	  available to accelerate real mode DOS programs.  However, any
1221	  recent version of DOSEMU, X, or vbetool should be fully
1222	  functional even without kernel VM86 support, as they will all
1223	  fall back to software emulation. Nevertheless, if you are using
1224	  a 16-bit DOS program where 16-bit performance matters, vm86
1225	  mode might be faster than emulation and you might want to
1226	  enable this option.
1227
1228	  Note that any app that works on a 64-bit kernel is unlikely to
1229	  need this option, as 64-bit kernels don't, and can't, support
1230	  V8086 mode. This option is also unrelated to 16-bit protected
1231	  mode and is not needed to run most 16-bit programs under Wine.
1232
1233	  Enabling this option increases the complexity of the kernel
1234	  and slows down exception handling a tiny bit.
1235
1236	  If unsure, say N here.
1237
1238config VM86
1239	bool
1240	default X86_LEGACY_VM86
1241
1242config X86_16BIT
1243	bool "Enable support for 16-bit segments" if EXPERT
1244	default y
1245	depends on MODIFY_LDT_SYSCALL
1246	help
1247	  This option is required by programs like Wine to run 16-bit
1248	  protected mode legacy code on x86 processors.  Disabling
1249	  this option saves about 300 bytes on i386, or around 6K text
1250	  plus 16K runtime memory on x86-64,
1251
1252config X86_ESPFIX32
1253	def_bool y
1254	depends on X86_16BIT && X86_32
1255
1256config X86_ESPFIX64
1257	def_bool y
1258	depends on X86_16BIT && X86_64
1259
1260config X86_VSYSCALL_EMULATION
1261	bool "Enable vsyscall emulation" if EXPERT
1262	default y
1263	depends on X86_64
1264	help
1265	  This enables emulation of the legacy vsyscall page.  Disabling
1266	  it is roughly equivalent to booting with vsyscall=none, except
1267	  that it will also disable the helpful warning if a program
1268	  tries to use a vsyscall.  With this option set to N, offending
1269	  programs will just segfault, citing addresses of the form
1270	  0xffffffffff600?00.
1271
1272	  This option is required by many programs built before 2013, and
1273	  care should be used even with newer programs if set to N.
1274
1275	  Disabling this option saves about 7K of kernel size and
1276	  possibly 4K of additional runtime pagetable memory.
1277
1278config X86_IOPL_IOPERM
1279	bool "IOPERM and IOPL Emulation"
1280	default y
1281	help
1282	  This enables the ioperm() and iopl() syscalls which are necessary
1283	  for legacy applications.
1284
1285	  Legacy IOPL support is an overbroad mechanism which allows user
1286	  space aside of accessing all 65536 I/O ports also to disable
1287	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1288	  capabilities and permission from potentially active security
1289	  modules.
1290
1291	  The emulation restricts the functionality of the syscall to
1292	  only allowing the full range I/O port access, but prevents the
1293	  ability to disable interrupts from user space which would be
1294	  granted if the hardware IOPL mechanism would be used.
1295
1296config TOSHIBA
1297	tristate "Toshiba Laptop support"
1298	depends on X86_32
1299	help
1300	  This adds a driver to safely access the System Management Mode of
1301	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1302	  not work on models with a Phoenix BIOS. The System Management Mode
1303	  is used to set the BIOS and power saving options on Toshiba portables.
1304
1305	  For information on utilities to make use of this driver see the
1306	  Toshiba Linux utilities web site at:
1307	  <http://www.buzzard.org.uk/toshiba/>.
1308
1309	  Say Y if you intend to run this kernel on a Toshiba portable.
1310	  Say N otherwise.
1311
1312config X86_REBOOTFIXUPS
1313	bool "Enable X86 board specific fixups for reboot"
1314	depends on X86_32
1315	help
1316	  This enables chipset and/or board specific fixups to be done
1317	  in order to get reboot to work correctly. This is only needed on
1318	  some combinations of hardware and BIOS. The symptom, for which
1319	  this config is intended, is when reboot ends with a stalled/hung
1320	  system.
1321
1322	  Currently, the only fixup is for the Geode machines using
1323	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1324
1325	  Say Y if you want to enable the fixup. Currently, it's safe to
1326	  enable this option even if you don't need it.
1327	  Say N otherwise.
1328
1329config MICROCODE
1330	def_bool y
1331	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1332	select CRYPTO_LIB_SHA256 if CPU_SUP_AMD
1333
1334config MICROCODE_INITRD32
1335	def_bool y
1336	depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1337
1338config MICROCODE_LATE_LOADING
1339	bool "Late microcode loading (DANGEROUS)"
1340	default n
1341	depends on MICROCODE && SMP
1342	help
1343	  Loading microcode late, when the system is up and executing instructions
1344	  is a tricky business and should be avoided if possible. Just the sequence
1345	  of synchronizing all cores and SMT threads is one fragile dance which does
1346	  not guarantee that cores might not softlock after the loading. Therefore,
1347	  use this at your own risk. Late loading taints the kernel unless the
1348	  microcode header indicates that it is safe for late loading via the
1349	  minimal revision check. This minimal revision check can be enforced on
1350	  the kernel command line with "microcode.minrev=Y".
1351
1352config MICROCODE_LATE_FORCE_MINREV
1353	bool "Enforce late microcode loading minimal revision check"
1354	default n
1355	depends on MICROCODE_LATE_LOADING
1356	help
1357	  To prevent that users load microcode late which modifies already
1358	  in use features, newer microcode patches have a minimum revision field
1359	  in the microcode header, which tells the kernel which minimum
1360	  revision must be active in the CPU to safely load that new microcode
1361	  late into the running system. If disabled the check will not
1362	  be enforced but the kernel will be tainted when the minimal
1363	  revision check fails.
1364
1365	  This minimal revision check can also be controlled via the
1366	  "microcode.minrev" parameter on the kernel command line.
1367
1368	  If unsure say Y.
1369
1370config X86_MSR
1371	tristate "/dev/cpu/*/msr - Model-specific register support"
1372	help
1373	  This device gives privileged processes access to the x86
1374	  Model-Specific Registers (MSRs).  It is a character device with
1375	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1376	  MSR accesses are directed to a specific CPU on multi-processor
1377	  systems.
1378
1379config X86_CPUID
1380	tristate "/dev/cpu/*/cpuid - CPU information support"
1381	help
1382	  This device gives processes access to the x86 CPUID instruction to
1383	  be executed on a specific processor.  It is a character device
1384	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1385	  /dev/cpu/31/cpuid.
1386
1387config HIGHMEM4G
1388	bool "High Memory Support"
1389	depends on X86_32
1390	help
1391	  Linux can use up to 4 Gigabytes of physical memory on x86 systems.
1392	  However, the address space of 32-bit x86 processors is only 4
1393	  Gigabytes large. That means that, if you have a large amount of
1394	  physical memory, not all of it can be "permanently mapped" by the
1395	  kernel. The physical memory that's not permanently mapped is called
1396	  "high memory".
1397
1398	  If you are compiling a kernel which will never run on a machine with
1399	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1400	  choice and suitable for most users). This will result in a "3GB/1GB"
1401	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1402	  space and the remaining part of the 4GB virtual memory space is used
1403	  by the kernel to permanently map as much physical memory as
1404	  possible.
1405
1406	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1407	  answer "Y" here.
1408
1409	  If unsure, say N.
1410
1411choice
1412	prompt "Memory split" if EXPERT
1413	default VMSPLIT_3G
1414	depends on X86_32
1415	help
1416	  Select the desired split between kernel and user memory.
1417
1418	  If the address range available to the kernel is less than the
1419	  physical memory installed, the remaining memory will be available
1420	  as "high memory". Accessing high memory is a little more costly
1421	  than low memory, as it needs to be mapped into the kernel first.
1422	  Note that increasing the kernel address space limits the range
1423	  available to user programs, making the address space there
1424	  tighter.  Selecting anything other than the default 3G/1G split
1425	  will also likely make your kernel incompatible with binary-only
1426	  kernel modules.
1427
1428	  If you are not absolutely sure what you are doing, leave this
1429	  option alone!
1430
1431	config VMSPLIT_3G
1432		bool "3G/1G user/kernel split"
1433	config VMSPLIT_3G_OPT
1434		depends on !X86_PAE
1435		bool "3G/1G user/kernel split (for full 1G low memory)"
1436	config VMSPLIT_2G
1437		bool "2G/2G user/kernel split"
1438	config VMSPLIT_2G_OPT
1439		depends on !X86_PAE
1440		bool "2G/2G user/kernel split (for full 2G low memory)"
1441	config VMSPLIT_1G
1442		bool "1G/3G user/kernel split"
1443endchoice
1444
1445config PAGE_OFFSET
1446	hex
1447	default 0xB0000000 if VMSPLIT_3G_OPT
1448	default 0x80000000 if VMSPLIT_2G
1449	default 0x78000000 if VMSPLIT_2G_OPT
1450	default 0x40000000 if VMSPLIT_1G
1451	default 0xC0000000
1452	depends on X86_32
1453
1454config HIGHMEM
1455	def_bool HIGHMEM4G
1456
1457config X86_PAE
1458	bool "PAE (Physical Address Extension) Support"
1459	depends on X86_32 && X86_HAVE_PAE
1460	select PHYS_ADDR_T_64BIT
1461	help
1462	  PAE is required for NX support, and furthermore enables
1463	  larger swapspace support for non-overcommit purposes. It
1464	  has the cost of more pagetable lookup overhead, and also
1465	  consumes more pagetable space per process.
1466
1467config X86_5LEVEL
1468	bool "Enable 5-level page tables support"
1469	default y
1470	select DYNAMIC_MEMORY_LAYOUT
1471	select SPARSEMEM_VMEMMAP
1472	depends on X86_64
1473	help
1474	  5-level paging enables access to larger address space:
1475	  up to 128 PiB of virtual address space and 4 PiB of
1476	  physical address space.
1477
1478	  It will be supported by future Intel CPUs.
1479
1480	  A kernel with the option enabled can be booted on machines that
1481	  support 4- or 5-level paging.
1482
1483	  See Documentation/arch/x86/x86_64/5level-paging.rst for more
1484	  information.
1485
1486	  Say N if unsure.
1487
1488config X86_DIRECT_GBPAGES
1489	def_bool y
1490	depends on X86_64
1491	help
1492	  Certain kernel features effectively disable kernel
1493	  linear 1 GB mappings (even if the CPU otherwise
1494	  supports them), so don't confuse the user by printing
1495	  that we have them enabled.
1496
1497config X86_CPA_STATISTICS
1498	bool "Enable statistic for Change Page Attribute"
1499	depends on DEBUG_FS
1500	help
1501	  Expose statistics about the Change Page Attribute mechanism, which
1502	  helps to determine the effectiveness of preserving large and huge
1503	  page mappings when mapping protections are changed.
1504
1505config X86_MEM_ENCRYPT
1506	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1507	select DYNAMIC_PHYSICAL_MASK
1508	def_bool n
1509
1510config AMD_MEM_ENCRYPT
1511	bool "AMD Secure Memory Encryption (SME) support"
1512	depends on X86_64 && CPU_SUP_AMD
1513	depends on EFI_STUB
1514	select DMA_COHERENT_POOL
1515	select ARCH_USE_MEMREMAP_PROT
1516	select INSTRUCTION_DECODER
1517	select ARCH_HAS_CC_PLATFORM
1518	select X86_MEM_ENCRYPT
1519	select UNACCEPTED_MEMORY
1520	select CRYPTO_LIB_AESGCM
1521	help
1522	  Say yes to enable support for the encryption of system memory.
1523	  This requires an AMD processor that supports Secure Memory
1524	  Encryption (SME).
1525
1526# Common NUMA Features
1527config NUMA
1528	bool "NUMA Memory Allocation and Scheduler Support"
1529	depends on SMP
1530	depends on X86_64
1531	select USE_PERCPU_NUMA_NODE_ID
1532	select OF_NUMA if OF
1533	help
1534	  Enable NUMA (Non-Uniform Memory Access) support.
1535
1536	  The kernel will try to allocate memory used by a CPU on the
1537	  local memory controller of the CPU and add some more
1538	  NUMA awareness to the kernel.
1539
1540	  For 64-bit this is recommended if the system is Intel Core i7
1541	  (or later), AMD Opteron, or EM64T NUMA.
1542
1543	  Otherwise, you should say N.
1544
1545config AMD_NUMA
1546	def_bool y
1547	prompt "Old style AMD Opteron NUMA detection"
1548	depends on X86_64 && NUMA && PCI
1549	help
1550	  Enable AMD NUMA node topology detection.  You should say Y here if
1551	  you have a multi processor AMD system. This uses an old method to
1552	  read the NUMA configuration directly from the builtin Northbridge
1553	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1554	  which also takes priority if both are compiled in.
1555
1556config X86_64_ACPI_NUMA
1557	def_bool y
1558	prompt "ACPI NUMA detection"
1559	depends on X86_64 && NUMA && ACPI && PCI
1560	select ACPI_NUMA
1561	help
1562	  Enable ACPI SRAT based node topology detection.
1563
1564config NODES_SHIFT
1565	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1566	range 1 10
1567	default "10" if MAXSMP
1568	default "6" if X86_64
1569	default "3"
1570	depends on NUMA
1571	help
1572	  Specify the maximum number of NUMA Nodes available on the target
1573	  system.  Increases memory reserved to accommodate various tables.
1574
1575config ARCH_FLATMEM_ENABLE
1576	def_bool y
1577	depends on X86_32 && !NUMA
1578
1579config ARCH_SPARSEMEM_ENABLE
1580	def_bool y
1581	select SPARSEMEM_STATIC if X86_32
1582	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1583
1584config ARCH_SPARSEMEM_DEFAULT
1585	def_bool X86_64 || (NUMA && X86_32)
1586
1587config ARCH_SELECT_MEMORY_MODEL
1588	def_bool y
1589	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1590
1591config ARCH_MEMORY_PROBE
1592	bool "Enable sysfs memory/probe interface"
1593	depends on MEMORY_HOTPLUG
1594	help
1595	  This option enables a sysfs memory/probe interface for testing.
1596	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1597	  If you are unsure how to answer this question, answer N.
1598
1599config ARCH_PROC_KCORE_TEXT
1600	def_bool y
1601	depends on X86_64 && PROC_KCORE
1602
1603config ILLEGAL_POINTER_VALUE
1604	hex
1605	default 0 if X86_32
1606	default 0xdead000000000000 if X86_64
1607
1608config X86_PMEM_LEGACY_DEVICE
1609	bool
1610
1611config X86_PMEM_LEGACY
1612	tristate "Support non-standard NVDIMMs and ADR protected memory"
1613	depends on PHYS_ADDR_T_64BIT
1614	depends on BLK_DEV
1615	select X86_PMEM_LEGACY_DEVICE
1616	select NUMA_KEEP_MEMINFO if NUMA
1617	select LIBNVDIMM
1618	help
1619	  Treat memory marked using the non-standard e820 type of 12 as used
1620	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1621	  The kernel will offer these regions to the 'pmem' driver so
1622	  they can be used for persistent storage.
1623
1624	  Say Y if unsure.
1625
1626config X86_CHECK_BIOS_CORRUPTION
1627	bool "Check for low memory corruption"
1628	help
1629	  Periodically check for memory corruption in low memory, which
1630	  is suspected to be caused by BIOS.  Even when enabled in the
1631	  configuration, it is disabled at runtime.  Enable it by
1632	  setting "memory_corruption_check=1" on the kernel command
1633	  line.  By default it scans the low 64k of memory every 60
1634	  seconds; see the memory_corruption_check_size and
1635	  memory_corruption_check_period parameters in
1636	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1637
1638	  When enabled with the default parameters, this option has
1639	  almost no overhead, as it reserves a relatively small amount
1640	  of memory and scans it infrequently.  It both detects corruption
1641	  and prevents it from affecting the running system.
1642
1643	  It is, however, intended as a diagnostic tool; if repeatable
1644	  BIOS-originated corruption always affects the same memory,
1645	  you can use memmap= to prevent the kernel from using that
1646	  memory.
1647
1648config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1649	bool "Set the default setting of memory_corruption_check"
1650	depends on X86_CHECK_BIOS_CORRUPTION
1651	default y
1652	help
1653	  Set whether the default state of memory_corruption_check is
1654	  on or off.
1655
1656config MATH_EMULATION
1657	bool
1658	depends on MODIFY_LDT_SYSCALL
1659	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1660	help
1661	  Linux can emulate a math coprocessor (used for floating point
1662	  operations) if you don't have one. 486DX and Pentium processors have
1663	  a math coprocessor built in, 486SX and 386 do not, unless you added
1664	  a 487DX or 387, respectively. (The messages during boot time can
1665	  give you some hints here ["man dmesg"].) Everyone needs either a
1666	  coprocessor or this emulation.
1667
1668	  If you don't have a math coprocessor, you need to say Y here; if you
1669	  say Y here even though you have a coprocessor, the coprocessor will
1670	  be used nevertheless. (This behavior can be changed with the kernel
1671	  command line option "no387", which comes handy if your coprocessor
1672	  is broken. Try "man bootparam" or see the documentation of your boot
1673	  loader (lilo or loadlin) about how to pass options to the kernel at
1674	  boot time.) This means that it is a good idea to say Y here if you
1675	  intend to use this kernel on different machines.
1676
1677	  More information about the internals of the Linux math coprocessor
1678	  emulation can be found in <file:arch/x86/math-emu/README>.
1679
1680	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1681	  kernel, it won't hurt.
1682
1683config MTRR
1684	def_bool y
1685	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1686	help
1687	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1688	  the Memory Type Range Registers (MTRRs) may be used to control
1689	  processor access to memory ranges. This is most useful if you have
1690	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1691	  allows bus write transfers to be combined into a larger transfer
1692	  before bursting over the PCI/AGP bus. This can increase performance
1693	  of image write operations 2.5 times or more. Saying Y here creates a
1694	  /proc/mtrr file which may be used to manipulate your processor's
1695	  MTRRs. Typically the X server should use this.
1696
1697	  This code has a reasonably generic interface so that similar
1698	  control registers on other processors can be easily supported
1699	  as well:
1700
1701	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1702	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1703	  these, the ARRs are used to emulate the MTRRs.
1704	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1705	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1706	  write-combining. All of these processors are supported by this code
1707	  and it makes sense to say Y here if you have one of them.
1708
1709	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1710	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1711	  can lead to all sorts of problems, so it's good to say Y here.
1712
1713	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1714	  just add about 9 KB to your kernel.
1715
1716	  See <file:Documentation/arch/x86/mtrr.rst> for more information.
1717
1718config MTRR_SANITIZER
1719	def_bool y
1720	prompt "MTRR cleanup support"
1721	depends on MTRR
1722	help
1723	  Convert MTRR layout from continuous to discrete, so X drivers can
1724	  add writeback entries.
1725
1726	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1727	  The largest mtrr entry size for a continuous block can be set with
1728	  mtrr_chunk_size.
1729
1730	  If unsure, say Y.
1731
1732config MTRR_SANITIZER_ENABLE_DEFAULT
1733	int "MTRR cleanup enable value (0-1)"
1734	range 0 1
1735	default "0"
1736	depends on MTRR_SANITIZER
1737	help
1738	  Enable mtrr cleanup default value
1739
1740config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1741	int "MTRR cleanup spare reg num (0-7)"
1742	range 0 7
1743	default "1"
1744	depends on MTRR_SANITIZER
1745	help
1746	  mtrr cleanup spare entries default, it can be changed via
1747	  mtrr_spare_reg_nr=N on the kernel command line.
1748
1749config X86_PAT
1750	def_bool y
1751	prompt "x86 PAT support" if EXPERT
1752	depends on MTRR
1753	select ARCH_USES_PG_ARCH_2
1754	help
1755	  Use PAT attributes to setup page level cache control.
1756
1757	  PATs are the modern equivalents of MTRRs and are much more
1758	  flexible than MTRRs.
1759
1760	  Say N here if you see bootup problems (boot crash, boot hang,
1761	  spontaneous reboots) or a non-working video driver.
1762
1763	  If unsure, say Y.
1764
1765config X86_UMIP
1766	def_bool y
1767	prompt "User Mode Instruction Prevention" if EXPERT
1768	help
1769	  User Mode Instruction Prevention (UMIP) is a security feature in
1770	  some x86 processors. If enabled, a general protection fault is
1771	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1772	  executed in user mode. These instructions unnecessarily expose
1773	  information about the hardware state.
1774
1775	  The vast majority of applications do not use these instructions.
1776	  For the very few that do, software emulation is provided in
1777	  specific cases in protected and virtual-8086 modes. Emulated
1778	  results are dummy.
1779
1780config CC_HAS_IBT
1781	# GCC >= 9 and binutils >= 2.29
1782	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1783	# Clang/LLVM >= 14
1784	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1785	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1786	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1787		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1788		  $(as-instr,endbr64)
1789
1790config X86_CET
1791	def_bool n
1792	help
1793	  CET features configured (Shadow stack or IBT)
1794
1795config X86_KERNEL_IBT
1796	prompt "Indirect Branch Tracking"
1797	def_bool y
1798	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1799	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1800	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1801	select OBJTOOL
1802	select X86_CET
1803	help
1804	  Build the kernel with support for Indirect Branch Tracking, a
1805	  hardware support course-grain forward-edge Control Flow Integrity
1806	  protection. It enforces that all indirect calls must land on
1807	  an ENDBR instruction, as such, the compiler will instrument the
1808	  code with them to make this happen.
1809
1810	  In addition to building the kernel with IBT, seal all functions that
1811	  are not indirect call targets, avoiding them ever becoming one.
1812
1813	  This requires LTO like objtool runs and will slow down the build. It
1814	  does significantly reduce the number of ENDBR instructions in the
1815	  kernel image.
1816
1817config X86_INTEL_MEMORY_PROTECTION_KEYS
1818	prompt "Memory Protection Keys"
1819	def_bool y
1820	# Note: only available in 64-bit mode
1821	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1822	select ARCH_USES_HIGH_VMA_FLAGS
1823	select ARCH_HAS_PKEYS
1824	help
1825	  Memory Protection Keys provides a mechanism for enforcing
1826	  page-based protections, but without requiring modification of the
1827	  page tables when an application changes protection domains.
1828
1829	  For details, see Documentation/core-api/protection-keys.rst
1830
1831	  If unsure, say y.
1832
1833config ARCH_PKEY_BITS
1834	int
1835	default 4
1836
1837choice
1838	prompt "TSX enable mode"
1839	depends on CPU_SUP_INTEL
1840	default X86_INTEL_TSX_MODE_OFF
1841	help
1842	  Intel's TSX (Transactional Synchronization Extensions) feature
1843	  allows to optimize locking protocols through lock elision which
1844	  can lead to a noticeable performance boost.
1845
1846	  On the other hand it has been shown that TSX can be exploited
1847	  to form side channel attacks (e.g. TAA) and chances are there
1848	  will be more of those attacks discovered in the future.
1849
1850	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1851	  might override this decision by tsx=on the command line parameter.
1852	  Even with TSX enabled, the kernel will attempt to enable the best
1853	  possible TAA mitigation setting depending on the microcode available
1854	  for the particular machine.
1855
1856	  This option allows to set the default tsx mode between tsx=on, =off
1857	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1858	  details.
1859
1860	  Say off if not sure, auto if TSX is in use but it should be used on safe
1861	  platforms or on if TSX is in use and the security aspect of tsx is not
1862	  relevant.
1863
1864config X86_INTEL_TSX_MODE_OFF
1865	bool "off"
1866	help
1867	  TSX is disabled if possible - equals to tsx=off command line parameter.
1868
1869config X86_INTEL_TSX_MODE_ON
1870	bool "on"
1871	help
1872	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1873	  line parameter.
1874
1875config X86_INTEL_TSX_MODE_AUTO
1876	bool "auto"
1877	help
1878	  TSX is enabled on TSX capable HW that is believed to be safe against
1879	  side channel attacks- equals the tsx=auto command line parameter.
1880endchoice
1881
1882config X86_SGX
1883	bool "Software Guard eXtensions (SGX)"
1884	depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1885	depends on CRYPTO=y
1886	depends on CRYPTO_SHA256=y
1887	select MMU_NOTIFIER
1888	select NUMA_KEEP_MEMINFO if NUMA
1889	select XARRAY_MULTI
1890	help
1891	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1892	  that can be used by applications to set aside private regions of code
1893	  and data, referred to as enclaves. An enclave's private memory can
1894	  only be accessed by code running within the enclave. Accesses from
1895	  outside the enclave, including other enclaves, are disallowed by
1896	  hardware.
1897
1898	  If unsure, say N.
1899
1900config X86_USER_SHADOW_STACK
1901	bool "X86 userspace shadow stack"
1902	depends on AS_WRUSS
1903	depends on X86_64
1904	select ARCH_USES_HIGH_VMA_FLAGS
1905	select ARCH_HAS_USER_SHADOW_STACK
1906	select X86_CET
1907	help
1908	  Shadow stack protection is a hardware feature that detects function
1909	  return address corruption.  This helps mitigate ROP attacks.
1910	  Applications must be enabled to use it, and old userspace does not
1911	  get protection "for free".
1912
1913	  CPUs supporting shadow stacks were first released in 2020.
1914
1915	  See Documentation/arch/x86/shstk.rst for more information.
1916
1917	  If unsure, say N.
1918
1919config INTEL_TDX_HOST
1920	bool "Intel Trust Domain Extensions (TDX) host support"
1921	depends on CPU_SUP_INTEL
1922	depends on X86_64
1923	depends on KVM_INTEL
1924	depends on X86_X2APIC
1925	select ARCH_KEEP_MEMBLOCK
1926	depends on CONTIG_ALLOC
1927	depends on !KEXEC_CORE
1928	depends on X86_MCE
1929	help
1930	  Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1931	  host and certain physical attacks.  This option enables necessary TDX
1932	  support in the host kernel to run confidential VMs.
1933
1934	  If unsure, say N.
1935
1936config EFI
1937	bool "EFI runtime service support"
1938	depends on ACPI
1939	select UCS2_STRING
1940	select EFI_RUNTIME_WRAPPERS
1941	select ARCH_USE_MEMREMAP_PROT
1942	select EFI_RUNTIME_MAP if KEXEC_CORE
1943	help
1944	  This enables the kernel to use EFI runtime services that are
1945	  available (such as the EFI variable services).
1946
1947	  This option is only useful on systems that have EFI firmware.
1948	  In addition, you should use the latest ELILO loader available
1949	  at <http://elilo.sourceforge.net> in order to take advantage
1950	  of EFI runtime services. However, even with this option, the
1951	  resultant kernel should continue to boot on existing non-EFI
1952	  platforms.
1953
1954config EFI_STUB
1955	bool "EFI stub support"
1956	depends on EFI
1957	select RELOCATABLE
1958	help
1959	  This kernel feature allows a bzImage to be loaded directly
1960	  by EFI firmware without the use of a bootloader.
1961
1962	  See Documentation/admin-guide/efi-stub.rst for more information.
1963
1964config EFI_HANDOVER_PROTOCOL
1965	bool "EFI handover protocol (DEPRECATED)"
1966	depends on EFI_STUB
1967	default y
1968	help
1969	  Select this in order to include support for the deprecated EFI
1970	  handover protocol, which defines alternative entry points into the
1971	  EFI stub.  This is a practice that has no basis in the UEFI
1972	  specification, and requires a priori knowledge on the part of the
1973	  bootloader about Linux/x86 specific ways of passing the command line
1974	  and initrd, and where in memory those assets may be loaded.
1975
1976	  If in doubt, say Y. Even though the corresponding support is not
1977	  present in upstream GRUB or other bootloaders, most distros build
1978	  GRUB with numerous downstream patches applied, and may rely on the
1979	  handover protocol as as result.
1980
1981config EFI_MIXED
1982	bool "EFI mixed-mode support"
1983	depends on EFI_STUB && X86_64
1984	help
1985	  Enabling this feature allows a 64-bit kernel to be booted
1986	  on a 32-bit firmware, provided that your CPU supports 64-bit
1987	  mode.
1988
1989	  Note that it is not possible to boot a mixed-mode enabled
1990	  kernel via the EFI boot stub - a bootloader that supports
1991	  the EFI handover protocol must be used.
1992
1993	  If unsure, say N.
1994
1995config EFI_RUNTIME_MAP
1996	bool "Export EFI runtime maps to sysfs" if EXPERT
1997	depends on EFI
1998	help
1999	  Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2000	  That memory map is required by the 2nd kernel to set up EFI virtual
2001	  mappings after kexec, but can also be used for debugging purposes.
2002
2003	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2004
2005source "kernel/Kconfig.hz"
2006
2007config ARCH_SUPPORTS_KEXEC
2008	def_bool y
2009
2010config ARCH_SUPPORTS_KEXEC_FILE
2011	def_bool X86_64
2012
2013config ARCH_SELECTS_KEXEC_FILE
2014	def_bool y
2015	depends on KEXEC_FILE
2016	select HAVE_IMA_KEXEC if IMA
2017
2018config ARCH_SUPPORTS_KEXEC_PURGATORY
2019	def_bool y
2020
2021config ARCH_SUPPORTS_KEXEC_SIG
2022	def_bool y
2023
2024config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2025	def_bool y
2026
2027config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2028	def_bool y
2029
2030config ARCH_SUPPORTS_KEXEC_JUMP
2031	def_bool y
2032
2033config ARCH_SUPPORTS_CRASH_DUMP
2034	def_bool X86_64 || (X86_32 && HIGHMEM)
2035
2036config ARCH_DEFAULT_CRASH_DUMP
2037	def_bool y
2038
2039config ARCH_SUPPORTS_CRASH_HOTPLUG
2040	def_bool y
2041
2042config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2043	def_bool CRASH_RESERVE
2044
2045config PHYSICAL_START
2046	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2047	default "0x1000000"
2048	help
2049	  This gives the physical address where the kernel is loaded.
2050
2051	  If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2052	  will decompress itself to above physical address and run from there.
2053	  Otherwise, bzImage will run from the address where it has been loaded
2054	  by the boot loader. The only exception is if it is loaded below the
2055	  above physical address, in which case it will relocate itself there.
2056
2057	  In normal kdump cases one does not have to set/change this option
2058	  as now bzImage can be compiled as a completely relocatable image
2059	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2060	  address. This option is mainly useful for the folks who don't want
2061	  to use a bzImage for capturing the crash dump and want to use a
2062	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2063	  to be specifically compiled to run from a specific memory area
2064	  (normally a reserved region) and this option comes handy.
2065
2066	  So if you are using bzImage for capturing the crash dump,
2067	  leave the value here unchanged to 0x1000000 and set
2068	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2069	  for capturing the crash dump change this value to start of
2070	  the reserved region.  In other words, it can be set based on
2071	  the "X" value as specified in the "crashkernel=YM@XM"
2072	  command line boot parameter passed to the panic-ed
2073	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2074	  for more details about crash dumps.
2075
2076	  Usage of bzImage for capturing the crash dump is recommended as
2077	  one does not have to build two kernels. Same kernel can be used
2078	  as production kernel and capture kernel. Above option should have
2079	  gone away after relocatable bzImage support is introduced. But it
2080	  is present because there are users out there who continue to use
2081	  vmlinux for dump capture. This option should go away down the
2082	  line.
2083
2084	  Don't change this unless you know what you are doing.
2085
2086config RELOCATABLE
2087	bool "Build a relocatable kernel"
2088	default y
2089	help
2090	  This builds a kernel image that retains relocation information
2091	  so it can be loaded someplace besides the default 1MB.
2092	  The relocations tend to make the kernel binary about 10% larger,
2093	  but are discarded at runtime.
2094
2095	  One use is for the kexec on panic case where the recovery kernel
2096	  must live at a different physical address than the primary
2097	  kernel.
2098
2099	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2100	  it has been loaded at and the compile time physical address
2101	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2102
2103config RANDOMIZE_BASE
2104	bool "Randomize the address of the kernel image (KASLR)"
2105	depends on RELOCATABLE
2106	default y
2107	help
2108	  In support of Kernel Address Space Layout Randomization (KASLR),
2109	  this randomizes the physical address at which the kernel image
2110	  is decompressed and the virtual address where the kernel
2111	  image is mapped, as a security feature that deters exploit
2112	  attempts relying on knowledge of the location of kernel
2113	  code internals.
2114
2115	  On 64-bit, the kernel physical and virtual addresses are
2116	  randomized separately. The physical address will be anywhere
2117	  between 16MB and the top of physical memory (up to 64TB). The
2118	  virtual address will be randomized from 16MB up to 1GB (9 bits
2119	  of entropy). Note that this also reduces the memory space
2120	  available to kernel modules from 1.5GB to 1GB.
2121
2122	  On 32-bit, the kernel physical and virtual addresses are
2123	  randomized together. They will be randomized from 16MB up to
2124	  512MB (8 bits of entropy).
2125
2126	  Entropy is generated using the RDRAND instruction if it is
2127	  supported. If RDTSC is supported, its value is mixed into
2128	  the entropy pool as well. If neither RDRAND nor RDTSC are
2129	  supported, then entropy is read from the i8254 timer. The
2130	  usable entropy is limited by the kernel being built using
2131	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2132	  minimum of 2MB. As a result, only 10 bits of entropy are
2133	  theoretically possible, but the implementations are further
2134	  limited due to memory layouts.
2135
2136	  If unsure, say Y.
2137
2138# Relocation on x86 needs some additional build support
2139config X86_NEED_RELOCS
2140	def_bool y
2141	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2142	select ARCH_VMLINUX_NEEDS_RELOCS
2143
2144config PHYSICAL_ALIGN
2145	hex "Alignment value to which kernel should be aligned"
2146	default "0x200000"
2147	range 0x2000 0x1000000 if X86_32
2148	range 0x200000 0x1000000 if X86_64
2149	help
2150	  This value puts the alignment restrictions on physical address
2151	  where kernel is loaded and run from. Kernel is compiled for an
2152	  address which meets above alignment restriction.
2153
2154	  If bootloader loads the kernel at a non-aligned address and
2155	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2156	  address aligned to above value and run from there.
2157
2158	  If bootloader loads the kernel at a non-aligned address and
2159	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2160	  load address and decompress itself to the address it has been
2161	  compiled for and run from there. The address for which kernel is
2162	  compiled already meets above alignment restrictions. Hence the
2163	  end result is that kernel runs from a physical address meeting
2164	  above alignment restrictions.
2165
2166	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2167	  this value must be a multiple of 0x200000.
2168
2169	  Don't change this unless you know what you are doing.
2170
2171config DYNAMIC_MEMORY_LAYOUT
2172	bool
2173	help
2174	  This option makes base addresses of vmalloc and vmemmap as well as
2175	  __PAGE_OFFSET movable during boot.
2176
2177config RANDOMIZE_MEMORY
2178	bool "Randomize the kernel memory sections"
2179	depends on X86_64
2180	depends on RANDOMIZE_BASE
2181	select DYNAMIC_MEMORY_LAYOUT
2182	default RANDOMIZE_BASE
2183	help
2184	  Randomizes the base virtual address of kernel memory sections
2185	  (physical memory mapping, vmalloc & vmemmap). This security feature
2186	  makes exploits relying on predictable memory locations less reliable.
2187
2188	  The order of allocations remains unchanged. Entropy is generated in
2189	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2190	  configuration have in average 30,000 different possible virtual
2191	  addresses for each memory section.
2192
2193	  If unsure, say Y.
2194
2195config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2196	hex "Physical memory mapping padding" if EXPERT
2197	depends on RANDOMIZE_MEMORY
2198	default "0xa" if MEMORY_HOTPLUG
2199	default "0x0"
2200	range 0x1 0x40 if MEMORY_HOTPLUG
2201	range 0x0 0x40
2202	help
2203	  Define the padding in terabytes added to the existing physical
2204	  memory size during kernel memory randomization. It is useful
2205	  for memory hotplug support but reduces the entropy available for
2206	  address randomization.
2207
2208	  If unsure, leave at the default value.
2209
2210config ADDRESS_MASKING
2211	bool "Linear Address Masking support"
2212	depends on X86_64
2213	depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
2214	help
2215	  Linear Address Masking (LAM) modifies the checking that is applied
2216	  to 64-bit linear addresses, allowing software to use of the
2217	  untranslated address bits for metadata.
2218
2219	  The capability can be used for efficient address sanitizers (ASAN)
2220	  implementation and for optimizations in JITs.
2221
2222config HOTPLUG_CPU
2223	def_bool y
2224	depends on SMP
2225
2226config COMPAT_VDSO
2227	def_bool n
2228	prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)"
2229	depends on COMPAT_32
2230	help
2231	  Certain buggy versions of glibc will crash if they are
2232	  presented with a 32-bit vDSO that is not mapped at the address
2233	  indicated in its segment table.
2234
2235	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2236	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2237	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2238	  the only released version with the bug, but OpenSUSE 9
2239	  contains a buggy "glibc 2.3.2".
2240
2241	  The symptom of the bug is that everything crashes on startup, saying:
2242	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2243
2244	  Saying Y here changes the default value of the vdso32 boot
2245	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2246	  This works around the glibc bug but hurts performance.
2247
2248	  If unsure, say N: if you are compiling your own kernel, you
2249	  are unlikely to be using a buggy version of glibc.
2250
2251choice
2252	prompt "vsyscall table for legacy applications"
2253	depends on X86_64
2254	default LEGACY_VSYSCALL_XONLY
2255	help
2256	  Legacy user code that does not know how to find the vDSO expects
2257	  to be able to issue three syscalls by calling fixed addresses in
2258	  kernel space. Since this location is not randomized with ASLR,
2259	  it can be used to assist security vulnerability exploitation.
2260
2261	  This setting can be changed at boot time via the kernel command
2262	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2263	  is deprecated and can only be enabled using the kernel command
2264	  line.
2265
2266	  On a system with recent enough glibc (2.14 or newer) and no
2267	  static binaries, you can say None without a performance penalty
2268	  to improve security.
2269
2270	  If unsure, select "Emulate execution only".
2271
2272	config LEGACY_VSYSCALL_XONLY
2273		bool "Emulate execution only"
2274		help
2275		  The kernel traps and emulates calls into the fixed vsyscall
2276		  address mapping and does not allow reads.  This
2277		  configuration is recommended when userspace might use the
2278		  legacy vsyscall area but support for legacy binary
2279		  instrumentation of legacy code is not needed.  It mitigates
2280		  certain uses of the vsyscall area as an ASLR-bypassing
2281		  buffer.
2282
2283	config LEGACY_VSYSCALL_NONE
2284		bool "None"
2285		help
2286		  There will be no vsyscall mapping at all. This will
2287		  eliminate any risk of ASLR bypass due to the vsyscall
2288		  fixed address mapping. Attempts to use the vsyscalls
2289		  will be reported to dmesg, so that either old or
2290		  malicious userspace programs can be identified.
2291
2292endchoice
2293
2294config CMDLINE_BOOL
2295	bool "Built-in kernel command line"
2296	help
2297	  Allow for specifying boot arguments to the kernel at
2298	  build time.  On some systems (e.g. embedded ones), it is
2299	  necessary or convenient to provide some or all of the
2300	  kernel boot arguments with the kernel itself (that is,
2301	  to not rely on the boot loader to provide them.)
2302
2303	  To compile command line arguments into the kernel,
2304	  set this option to 'Y', then fill in the
2305	  boot arguments in CONFIG_CMDLINE.
2306
2307	  Systems with fully functional boot loaders (i.e. non-embedded)
2308	  should leave this option set to 'N'.
2309
2310config CMDLINE
2311	string "Built-in kernel command string"
2312	depends on CMDLINE_BOOL
2313	default ""
2314	help
2315	  Enter arguments here that should be compiled into the kernel
2316	  image and used at boot time.  If the boot loader provides a
2317	  command line at boot time, it is appended to this string to
2318	  form the full kernel command line, when the system boots.
2319
2320	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2321	  change this behavior.
2322
2323	  In most cases, the command line (whether built-in or provided
2324	  by the boot loader) should specify the device for the root
2325	  file system.
2326
2327config CMDLINE_OVERRIDE
2328	bool "Built-in command line overrides boot loader arguments"
2329	depends on CMDLINE_BOOL && CMDLINE != ""
2330	help
2331	  Set this option to 'Y' to have the kernel ignore the boot loader
2332	  command line, and use ONLY the built-in command line.
2333
2334	  This is used to work around broken boot loaders.  This should
2335	  be set to 'N' under normal conditions.
2336
2337config MODIFY_LDT_SYSCALL
2338	bool "Enable the LDT (local descriptor table)" if EXPERT
2339	default y
2340	help
2341	  Linux can allow user programs to install a per-process x86
2342	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2343	  call.  This is required to run 16-bit or segmented code such as
2344	  DOSEMU or some Wine programs.  It is also used by some very old
2345	  threading libraries.
2346
2347	  Enabling this feature adds a small amount of overhead to
2348	  context switches and increases the low-level kernel attack
2349	  surface.  Disabling it removes the modify_ldt(2) system call.
2350
2351	  Saying 'N' here may make sense for embedded or server kernels.
2352
2353config STRICT_SIGALTSTACK_SIZE
2354	bool "Enforce strict size checking for sigaltstack"
2355	depends on DYNAMIC_SIGFRAME
2356	help
2357	  For historical reasons MINSIGSTKSZ is a constant which became
2358	  already too small with AVX512 support. Add a mechanism to
2359	  enforce strict checking of the sigaltstack size against the
2360	  real size of the FPU frame. This option enables the check
2361	  by default. It can also be controlled via the kernel command
2362	  line option 'strict_sas_size' independent of this config
2363	  switch. Enabling it might break existing applications which
2364	  allocate a too small sigaltstack but 'work' because they
2365	  never get a signal delivered.
2366
2367	  Say 'N' unless you want to really enforce this check.
2368
2369config CFI_AUTO_DEFAULT
2370	bool "Attempt to use FineIBT by default at boot time"
2371	depends on FINEIBT
2372	depends on !RUST || RUSTC_VERSION >= 108800
2373	default y
2374	help
2375	  Attempt to use FineIBT by default at boot time. If enabled,
2376	  this is the same as booting with "cfi=auto". If disabled,
2377	  this is the same as booting with "cfi=kcfi".
2378
2379source "kernel/livepatch/Kconfig"
2380
2381config X86_BUS_LOCK_DETECT
2382	bool "Split Lock Detect and Bus Lock Detect support"
2383	depends on CPU_SUP_INTEL || CPU_SUP_AMD
2384	default y
2385	help
2386	  Enable Split Lock Detect and Bus Lock Detect functionalities.
2387	  See <file:Documentation/arch/x86/buslock.rst> for more information.
2388
2389endmenu
2390
2391config CC_HAS_NAMED_AS
2392	def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
2393	depends on CC_IS_GCC
2394
2395#
2396# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN)
2397# are incompatible with named address spaces with GCC < 13.3
2398# (see GCC PR sanitizer/111736 and also PR sanitizer/115172).
2399#
2400
2401config CC_HAS_NAMED_AS_FIXED_SANITIZERS
2402	def_bool y
2403	depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300
2404	depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200
2405
2406config USE_X86_SEG_SUPPORT
2407	def_bool CC_HAS_NAMED_AS
2408	depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS
2409
2410config CC_HAS_SLS
2411	def_bool $(cc-option,-mharden-sls=all)
2412
2413config CC_HAS_RETURN_THUNK
2414	def_bool $(cc-option,-mfunction-return=thunk-extern)
2415
2416config CC_HAS_ENTRY_PADDING
2417	def_bool $(cc-option,-fpatchable-function-entry=16,16)
2418
2419config CC_HAS_KCFI_ARITY
2420	def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity)
2421	depends on CC_IS_CLANG && !RUST
2422
2423config FUNCTION_PADDING_CFI
2424	int
2425	default 59 if FUNCTION_ALIGNMENT_64B
2426	default 27 if FUNCTION_ALIGNMENT_32B
2427	default 11 if FUNCTION_ALIGNMENT_16B
2428	default  3 if FUNCTION_ALIGNMENT_8B
2429	default  0
2430
2431# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2432# except Kconfig can't do arithmetic :/
2433config FUNCTION_PADDING_BYTES
2434	int
2435	default FUNCTION_PADDING_CFI if CFI_CLANG
2436	default FUNCTION_ALIGNMENT
2437
2438config CALL_PADDING
2439	def_bool n
2440	depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2441	select FUNCTION_ALIGNMENT_16B
2442
2443config FINEIBT
2444	def_bool y
2445	depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2446	select CALL_PADDING
2447
2448config FINEIBT_BHI
2449	def_bool y
2450	depends on FINEIBT && CC_HAS_KCFI_ARITY
2451
2452config HAVE_CALL_THUNKS
2453	def_bool y
2454	depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2455
2456config CALL_THUNKS
2457	def_bool n
2458	select CALL_PADDING
2459
2460config PREFIX_SYMBOLS
2461	def_bool y
2462	depends on CALL_PADDING && !CFI_CLANG
2463
2464menuconfig CPU_MITIGATIONS
2465	bool "Mitigations for CPU vulnerabilities"
2466	default y
2467	help
2468	  Say Y here to enable options which enable mitigations for hardware
2469	  vulnerabilities (usually related to speculative execution).
2470	  Mitigations can be disabled or restricted to SMT systems at runtime
2471	  via the "mitigations" kernel parameter.
2472
2473	  If you say N, all mitigations will be disabled.  This CANNOT be
2474	  overridden at runtime.
2475
2476	  Say 'Y', unless you really know what you are doing.
2477
2478if CPU_MITIGATIONS
2479
2480config MITIGATION_PAGE_TABLE_ISOLATION
2481	bool "Remove the kernel mapping in user mode"
2482	default y
2483	depends on (X86_64 || X86_PAE)
2484	help
2485	  This feature reduces the number of hardware side channels by
2486	  ensuring that the majority of kernel addresses are not mapped
2487	  into userspace.
2488
2489	  See Documentation/arch/x86/pti.rst for more details.
2490
2491config MITIGATION_RETPOLINE
2492	bool "Avoid speculative indirect branches in kernel"
2493	select OBJTOOL if HAVE_OBJTOOL
2494	default y
2495	help
2496	  Compile kernel with the retpoline compiler options to guard against
2497	  kernel-to-user data leaks by avoiding speculative indirect
2498	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2499	  support for full protection. The kernel may run slower.
2500
2501config MITIGATION_RETHUNK
2502	bool "Enable return-thunks"
2503	depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2504	select OBJTOOL if HAVE_OBJTOOL
2505	default y if X86_64
2506	help
2507	  Compile the kernel with the return-thunks compiler option to guard
2508	  against kernel-to-user data leaks by avoiding return speculation.
2509	  Requires a compiler with -mfunction-return=thunk-extern
2510	  support for full protection. The kernel may run slower.
2511
2512config MITIGATION_UNRET_ENTRY
2513	bool "Enable UNRET on kernel entry"
2514	depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2515	default y
2516	help
2517	  Compile the kernel with support for the retbleed=unret mitigation.
2518
2519config MITIGATION_CALL_DEPTH_TRACKING
2520	bool "Mitigate RSB underflow with call depth tracking"
2521	depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2522	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2523	select CALL_THUNKS
2524	default y
2525	help
2526	  Compile the kernel with call depth tracking to mitigate the Intel
2527	  SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off
2528	  by default and needs to be enabled on the kernel command line via the
2529	  retbleed=stuff option. For non-affected systems the overhead of this
2530	  option is marginal as the call depth tracking is using run-time
2531	  generated call thunks in a compiler generated padding area and call
2532	  patching. This increases text size by ~5%. For non affected systems
2533	  this space is unused. On affected SKL systems this results in a
2534	  significant performance gain over the IBRS mitigation.
2535
2536config CALL_THUNKS_DEBUG
2537	bool "Enable call thunks and call depth tracking debugging"
2538	depends on MITIGATION_CALL_DEPTH_TRACKING
2539	select FUNCTION_ALIGNMENT_32B
2540	default n
2541	help
2542	  Enable call/ret counters for imbalance detection and build in
2543	  a noisy dmesg about callthunks generation and call patching for
2544	  trouble shooting. The debug prints need to be enabled on the
2545	  kernel command line with 'debug-callthunks'.
2546	  Only enable this when you are debugging call thunks as this
2547	  creates a noticeable runtime overhead. If unsure say N.
2548
2549config MITIGATION_IBPB_ENTRY
2550	bool "Enable IBPB on kernel entry"
2551	depends on CPU_SUP_AMD && X86_64
2552	default y
2553	help
2554	  Compile the kernel with support for the retbleed=ibpb and
2555	  spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations.
2556
2557config MITIGATION_IBRS_ENTRY
2558	bool "Enable IBRS on kernel entry"
2559	depends on CPU_SUP_INTEL && X86_64
2560	default y
2561	help
2562	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2563	  This mitigates both spectre_v2 and retbleed at great cost to
2564	  performance.
2565
2566config MITIGATION_SRSO
2567	bool "Mitigate speculative RAS overflow on AMD"
2568	depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2569	default y
2570	help
2571	  Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2572
2573config MITIGATION_SLS
2574	bool "Mitigate Straight-Line-Speculation"
2575	depends on CC_HAS_SLS && X86_64
2576	select OBJTOOL if HAVE_OBJTOOL
2577	default n
2578	help
2579	  Compile the kernel with straight-line-speculation options to guard
2580	  against straight line speculation. The kernel image might be slightly
2581	  larger.
2582
2583config MITIGATION_GDS
2584	bool "Mitigate Gather Data Sampling"
2585	depends on CPU_SUP_INTEL
2586	default y
2587	help
2588	  Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
2589	  vulnerability which allows unprivileged speculative access to data
2590	  which was previously stored in vector registers. The attacker uses gather
2591	  instructions to infer the stale vector register data.
2592
2593config MITIGATION_RFDS
2594	bool "RFDS Mitigation"
2595	depends on CPU_SUP_INTEL
2596	default y
2597	help
2598	  Enable mitigation for Register File Data Sampling (RFDS) by default.
2599	  RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2600	  allows unprivileged speculative access to stale data previously
2601	  stored in floating point, vector and integer registers.
2602	  See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2603
2604config MITIGATION_SPECTRE_BHI
2605	bool "Mitigate Spectre-BHB (Branch History Injection)"
2606	depends on CPU_SUP_INTEL
2607	default y
2608	help
2609	  Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2610	  where the branch history buffer is poisoned to speculatively steer
2611	  indirect branches.
2612	  See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2613
2614config MITIGATION_MDS
2615	bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
2616	depends on CPU_SUP_INTEL
2617	default y
2618	help
2619	  Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
2620	  a hardware vulnerability which allows unprivileged speculative access
2621	  to data which is available in various CPU internal buffers.
2622	  See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
2623
2624config MITIGATION_TAA
2625	bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
2626	depends on CPU_SUP_INTEL
2627	default y
2628	help
2629	  Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
2630	  vulnerability that allows unprivileged speculative access to data
2631	  which is available in various CPU internal buffers by using
2632	  asynchronous aborts within an Intel TSX transactional region.
2633	  See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
2634
2635config MITIGATION_MMIO_STALE_DATA
2636	bool "Mitigate MMIO Stale Data hardware bug"
2637	depends on CPU_SUP_INTEL
2638	default y
2639	help
2640	  Enable mitigation for MMIO Stale Data hardware bugs.  Processor MMIO
2641	  Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
2642	  vulnerabilities that can expose data. The vulnerabilities require the
2643	  attacker to have access to MMIO.
2644	  See also
2645	  <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
2646
2647config MITIGATION_L1TF
2648	bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
2649	depends on CPU_SUP_INTEL
2650	default y
2651	help
2652	  Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
2653	  hardware vulnerability which allows unprivileged speculative access to data
2654	  available in the Level 1 Data Cache.
2655	  See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
2656
2657config MITIGATION_RETBLEED
2658	bool "Mitigate RETBleed hardware bug"
2659	depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
2660	default y
2661	help
2662	  Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
2663	  with Return Instructions) vulnerability.  RETBleed is a speculative
2664	  execution attack which takes advantage of microarchitectural behavior
2665	  in many modern microprocessors, similar to Spectre v2. An
2666	  unprivileged attacker can use these flaws to bypass conventional
2667	  memory security restrictions to gain read access to privileged memory
2668	  that would otherwise be inaccessible.
2669
2670config MITIGATION_SPECTRE_V1
2671	bool "Mitigate SPECTRE V1 hardware bug"
2672	default y
2673	help
2674	  Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
2675	  class of side channel attacks that takes advantage of speculative
2676	  execution that bypasses conditional branch instructions used for
2677	  memory access bounds check.
2678	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2679
2680config MITIGATION_SPECTRE_V2
2681	bool "Mitigate SPECTRE V2 hardware bug"
2682	default y
2683	help
2684	  Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
2685	  V2 is a class of side channel attacks that takes advantage of
2686	  indirect branch predictors inside the processor. In Spectre variant 2
2687	  attacks, the attacker can steer speculative indirect branches in the
2688	  victim to gadget code by poisoning the branch target buffer of a CPU
2689	  used for predicting indirect branch addresses.
2690	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2691
2692config MITIGATION_SRBDS
2693	bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
2694	depends on CPU_SUP_INTEL
2695	default y
2696	help
2697	  Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
2698	  SRBDS is a hardware vulnerability that allows Microarchitectural Data
2699	  Sampling (MDS) techniques to infer values returned from special
2700	  register accesses. An unprivileged user can extract values returned
2701	  from RDRAND and RDSEED executed on another core or sibling thread
2702	  using MDS techniques.
2703	  See also
2704	  <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
2705
2706config MITIGATION_SSB
2707	bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
2708	default y
2709	help
2710	  Enable mitigation for Speculative Store Bypass (SSB). SSB is a
2711	  hardware security vulnerability and its exploitation takes advantage
2712	  of speculative execution in a similar way to the Meltdown and Spectre
2713	  security vulnerabilities.
2714
2715config MITIGATION_ITS
2716	bool "Enable Indirect Target Selection mitigation"
2717	depends on CPU_SUP_INTEL && X86_64
2718	depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK
2719	select EXECMEM
2720	default y
2721	help
2722	  Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in
2723	  BPU on some Intel CPUs that may allow Spectre V2 style attacks. If
2724	  disabled, mitigation cannot be enabled via cmdline.
2725	  See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst>
2726
2727endif
2728
2729config ARCH_HAS_ADD_PAGES
2730	def_bool y
2731	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2732
2733menu "Power management and ACPI options"
2734
2735config ARCH_HIBERNATION_HEADER
2736	def_bool y
2737	depends on HIBERNATION
2738
2739source "kernel/power/Kconfig"
2740
2741source "drivers/acpi/Kconfig"
2742
2743config X86_APM_BOOT
2744	def_bool y
2745	depends on APM
2746
2747menuconfig APM
2748	tristate "APM (Advanced Power Management) BIOS support"
2749	depends on X86_32 && PM_SLEEP
2750	help
2751	  APM is a BIOS specification for saving power using several different
2752	  techniques. This is mostly useful for battery powered laptops with
2753	  APM compliant BIOSes. If you say Y here, the system time will be
2754	  reset after a RESUME operation, the /proc/apm device will provide
2755	  battery status information, and user-space programs will receive
2756	  notification of APM "events" (e.g. battery status change).
2757
2758	  If you select "Y" here, you can disable actual use of the APM
2759	  BIOS by passing the "apm=off" option to the kernel at boot time.
2760
2761	  Note that the APM support is almost completely disabled for
2762	  machines with more than one CPU.
2763
2764	  In order to use APM, you will need supporting software. For location
2765	  and more information, read <file:Documentation/power/apm-acpi.rst>
2766	  and the Battery Powered Linux mini-HOWTO, available from
2767	  <http://www.tldp.org/docs.html#howto>.
2768
2769	  This driver does not spin down disk drives (see the hdparm(8)
2770	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2771	  VESA-compliant "green" monitors.
2772
2773	  This driver does not support the TI 4000M TravelMate and the ACER
2774	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2775	  desktop machines also don't have compliant BIOSes, and this driver
2776	  may cause those machines to panic during the boot phase.
2777
2778	  Generally, if you don't have a battery in your machine, there isn't
2779	  much point in using this driver and you should say N. If you get
2780	  random kernel OOPSes or reboots that don't seem to be related to
2781	  anything, try disabling/enabling this option (or disabling/enabling
2782	  APM in your BIOS).
2783
2784	  Some other things you should try when experiencing seemingly random,
2785	  "weird" problems:
2786
2787	  1) make sure that you have enough swap space and that it is
2788	  enabled.
2789	  2) pass the "idle=poll" option to the kernel
2790	  3) switch on floating point emulation in the kernel and pass
2791	  the "no387" option to the kernel
2792	  4) pass the "floppy=nodma" option to the kernel
2793	  5) pass the "mem=4M" option to the kernel (thereby disabling
2794	  all but the first 4 MB of RAM)
2795	  6) make sure that the CPU is not over clocked.
2796	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2797	  8) disable the cache from your BIOS settings
2798	  9) install a fan for the video card or exchange video RAM
2799	  10) install a better fan for the CPU
2800	  11) exchange RAM chips
2801	  12) exchange the motherboard.
2802
2803	  To compile this driver as a module, choose M here: the
2804	  module will be called apm.
2805
2806if APM
2807
2808config APM_IGNORE_USER_SUSPEND
2809	bool "Ignore USER SUSPEND"
2810	help
2811	  This option will ignore USER SUSPEND requests. On machines with a
2812	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2813	  series notebooks, it is necessary to say Y because of a BIOS bug.
2814
2815config APM_DO_ENABLE
2816	bool "Enable PM at boot time"
2817	help
2818	  Enable APM features at boot time. From page 36 of the APM BIOS
2819	  specification: "When disabled, the APM BIOS does not automatically
2820	  power manage devices, enter the Standby State, enter the Suspend
2821	  State, or take power saving steps in response to CPU Idle calls."
2822	  This driver will make CPU Idle calls when Linux is idle (unless this
2823	  feature is turned off -- see "Do CPU IDLE calls", below). This
2824	  should always save battery power, but more complicated APM features
2825	  will be dependent on your BIOS implementation. You may need to turn
2826	  this option off if your computer hangs at boot time when using APM
2827	  support, or if it beeps continuously instead of suspending. Turn
2828	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2829	  T400CDT. This is off by default since most machines do fine without
2830	  this feature.
2831
2832config APM_CPU_IDLE
2833	depends on CPU_IDLE
2834	bool "Make CPU Idle calls when idle"
2835	help
2836	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2837	  On some machines, this can activate improved power savings, such as
2838	  a slowed CPU clock rate, when the machine is idle. These idle calls
2839	  are made after the idle loop has run for some length of time (e.g.,
2840	  333 mS). On some machines, this will cause a hang at boot time or
2841	  whenever the CPU becomes idle. (On machines with more than one CPU,
2842	  this option does nothing.)
2843
2844config APM_DISPLAY_BLANK
2845	bool "Enable console blanking using APM"
2846	help
2847	  Enable console blanking using the APM. Some laptops can use this to
2848	  turn off the LCD backlight when the screen blanker of the Linux
2849	  virtual console blanks the screen. Note that this is only used by
2850	  the virtual console screen blanker, and won't turn off the backlight
2851	  when using the X Window system. This also doesn't have anything to
2852	  do with your VESA-compliant power-saving monitor. Further, this
2853	  option doesn't work for all laptops -- it might not turn off your
2854	  backlight at all, or it might print a lot of errors to the console,
2855	  especially if you are using gpm.
2856
2857config APM_ALLOW_INTS
2858	bool "Allow interrupts during APM BIOS calls"
2859	help
2860	  Normally we disable external interrupts while we are making calls to
2861	  the APM BIOS as a measure to lessen the effects of a badly behaving
2862	  BIOS implementation.  The BIOS should reenable interrupts if it
2863	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2864	  many of the newer IBM Thinkpads.  If you experience hangs when you
2865	  suspend, try setting this to Y.  Otherwise, say N.
2866
2867endif # APM
2868
2869source "drivers/cpufreq/Kconfig"
2870
2871source "drivers/cpuidle/Kconfig"
2872
2873source "drivers/idle/Kconfig"
2874
2875endmenu
2876
2877menu "Bus options (PCI etc.)"
2878
2879choice
2880	prompt "PCI access mode"
2881	depends on X86_32 && PCI
2882	default PCI_GOANY
2883	help
2884	  On PCI systems, the BIOS can be used to detect the PCI devices and
2885	  determine their configuration. However, some old PCI motherboards
2886	  have BIOS bugs and may crash if this is done. Also, some embedded
2887	  PCI-based systems don't have any BIOS at all. Linux can also try to
2888	  detect the PCI hardware directly without using the BIOS.
2889
2890	  With this option, you can specify how Linux should detect the
2891	  PCI devices. If you choose "BIOS", the BIOS will be used,
2892	  if you choose "Direct", the BIOS won't be used, and if you
2893	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2894	  If you choose "Any", the kernel will try MMCONFIG, then the
2895	  direct access method and falls back to the BIOS if that doesn't
2896	  work. If unsure, go with the default, which is "Any".
2897
2898config PCI_GOBIOS
2899	bool "BIOS"
2900
2901config PCI_GOMMCONFIG
2902	bool "MMConfig"
2903
2904config PCI_GODIRECT
2905	bool "Direct"
2906
2907config PCI_GOOLPC
2908	bool "OLPC XO-1"
2909	depends on OLPC
2910
2911config PCI_GOANY
2912	bool "Any"
2913
2914endchoice
2915
2916config PCI_BIOS
2917	def_bool y
2918	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2919
2920# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2921config PCI_DIRECT
2922	def_bool y
2923	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2924
2925config PCI_MMCONFIG
2926	bool "Support mmconfig PCI config space access" if X86_64
2927	default y
2928	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2929	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2930	help
2931	  Add support for accessing the PCI configuration space as a memory
2932	  mapped area. It is the recommended method if the system supports
2933	  this (it must have PCI Express and ACPI for it to be available).
2934
2935	  In the unlikely case that enabling this configuration option causes
2936	  problems, the mechanism can be switched off with the 'pci=nommconf'
2937	  command line parameter.
2938
2939	  Say N only if you are sure that your platform does not support this
2940	  access method or you have problems caused by it.
2941
2942	  Say Y otherwise.
2943
2944config PCI_OLPC
2945	def_bool y
2946	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2947
2948config PCI_XEN
2949	def_bool y
2950	depends on PCI && XEN
2951
2952config MMCONF_FAM10H
2953	def_bool y
2954	depends on X86_64 && PCI_MMCONFIG && ACPI
2955
2956config PCI_CNB20LE_QUIRK
2957	bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT
2958	depends on X86_32 && PCI
2959	help
2960	  Read the PCI windows out of the CNB20LE host bridge. This allows
2961	  PCI hotplug to work on systems with the CNB20LE chipset which do
2962	  not have ACPI.
2963
2964	  The ServerWorks (later Broadcom) CNB20LE was a chipset designed
2965	  most probably only for Pentium III.
2966
2967	  To find out if you have such a chipset, search for a PCI device with
2968	  1166:0009 PCI IDs, for example by executing
2969		lspci -nn | grep '1166:0009'
2970	  The code is inactive if there is none.
2971
2972	  There's no public spec for this chipset, and this functionality
2973	  is known to be incomplete.
2974
2975	  You should say N unless you know you need this.
2976
2977config ISA_BUS
2978	bool "ISA bus support on modern systems" if EXPERT
2979	help
2980	  Expose ISA bus device drivers and options available for selection and
2981	  configuration. Enable this option if your target machine has an ISA
2982	  bus. ISA is an older system, displaced by PCI and newer bus
2983	  architectures -- if your target machine is modern, it probably does
2984	  not have an ISA bus.
2985
2986	  If unsure, say N.
2987
2988# x86_64 have no ISA slots, but can have ISA-style DMA.
2989config ISA_DMA_API
2990	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2991	default y
2992	help
2993	  Enables ISA-style DMA support for devices requiring such controllers.
2994	  If unsure, say Y.
2995
2996if X86_32
2997
2998config ISA
2999	bool "ISA support"
3000	help
3001	  Find out whether you have ISA slots on your motherboard.  ISA is the
3002	  name of a bus system, i.e. the way the CPU talks to the other stuff
3003	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
3004	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
3005	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
3006
3007config SCx200
3008	tristate "NatSemi SCx200 support"
3009	help
3010	  This provides basic support for National Semiconductor's
3011	  (now AMD's) Geode processors.  The driver probes for the
3012	  PCI-IDs of several on-chip devices, so its a good dependency
3013	  for other scx200_* drivers.
3014
3015	  If compiled as a module, the driver is named scx200.
3016
3017config SCx200HR_TIMER
3018	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
3019	depends on SCx200
3020	default y
3021	help
3022	  This driver provides a clocksource built upon the on-chip
3023	  27MHz high-resolution timer.  Its also a workaround for
3024	  NSC Geode SC-1100's buggy TSC, which loses time when the
3025	  processor goes idle (as is done by the scheduler).  The
3026	  other workaround is idle=poll boot option.
3027
3028config OLPC
3029	bool "One Laptop Per Child support"
3030	depends on !X86_PAE
3031	select GPIOLIB
3032	select OF
3033	select OF_PROMTREE
3034	select IRQ_DOMAIN
3035	select OLPC_EC
3036	help
3037	  Add support for detecting the unique features of the OLPC
3038	  XO hardware.
3039
3040config OLPC_XO1_PM
3041	bool "OLPC XO-1 Power Management"
3042	depends on OLPC && MFD_CS5535=y && PM_SLEEP
3043	help
3044	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
3045
3046config OLPC_XO1_RTC
3047	bool "OLPC XO-1 Real Time Clock"
3048	depends on OLPC_XO1_PM && RTC_DRV_CMOS
3049	help
3050	  Add support for the XO-1 real time clock, which can be used as a
3051	  programmable wakeup source.
3052
3053config OLPC_XO1_SCI
3054	bool "OLPC XO-1 SCI extras"
3055	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
3056	depends on INPUT=y
3057	select POWER_SUPPLY
3058	help
3059	  Add support for SCI-based features of the OLPC XO-1 laptop:
3060	   - EC-driven system wakeups
3061	   - Power button
3062	   - Ebook switch
3063	   - Lid switch
3064	   - AC adapter status updates
3065	   - Battery status updates
3066
3067config OLPC_XO15_SCI
3068	bool "OLPC XO-1.5 SCI extras"
3069	depends on OLPC && ACPI
3070	select POWER_SUPPLY
3071	help
3072	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
3073	   - EC-driven system wakeups
3074	   - AC adapter status updates
3075	   - Battery status updates
3076
3077config GEODE_COMMON
3078	bool
3079
3080config ALIX
3081	bool "PCEngines ALIX System Support (LED setup)"
3082	select GPIOLIB
3083	select GEODE_COMMON
3084	help
3085	  This option enables system support for the PCEngines ALIX.
3086	  At present this just sets up LEDs for GPIO control on
3087	  ALIX2/3/6 boards.  However, other system specific setup should
3088	  get added here.
3089
3090	  Note: You must still enable the drivers for GPIO and LED support
3091	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
3092
3093	  Note: You have to set alix.force=1 for boards with Award BIOS.
3094
3095config NET5501
3096	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
3097	select GPIOLIB
3098	select GEODE_COMMON
3099	help
3100	  This option enables system support for the Soekris Engineering net5501.
3101
3102config GEOS
3103	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
3104	select GPIOLIB
3105	select GEODE_COMMON
3106	depends on DMI
3107	help
3108	  This option enables system support for the Traverse Technologies GEOS.
3109
3110config TS5500
3111	bool "Technologic Systems TS-5500 platform support"
3112	depends on MELAN
3113	select CHECK_SIGNATURE
3114	select NEW_LEDS
3115	select LEDS_CLASS
3116	help
3117	  This option enables system support for the Technologic Systems TS-5500.
3118
3119endif # X86_32
3120
3121config AMD_NB
3122	def_bool y
3123	depends on AMD_NODE
3124
3125config AMD_NODE
3126	def_bool y
3127	depends on CPU_SUP_AMD && PCI
3128
3129endmenu
3130
3131menu "Binary Emulations"
3132
3133config IA32_EMULATION
3134	bool "IA32 Emulation"
3135	depends on X86_64
3136	select ARCH_WANT_OLD_COMPAT_IPC
3137	select BINFMT_ELF
3138	select COMPAT_OLD_SIGACTION
3139	help
3140	  Include code to run legacy 32-bit programs under a
3141	  64-bit kernel. You should likely turn this on, unless you're
3142	  100% sure that you don't have any 32-bit programs left.
3143
3144config IA32_EMULATION_DEFAULT_DISABLED
3145	bool "IA32 emulation disabled by default"
3146	default n
3147	depends on IA32_EMULATION
3148	help
3149	  Make IA32 emulation disabled by default. This prevents loading 32-bit
3150	  processes and access to 32-bit syscalls. If unsure, leave it to its
3151	  default value.
3152
3153config X86_X32_ABI
3154	bool "x32 ABI for 64-bit mode"
3155	depends on X86_64
3156	# llvm-objcopy does not convert x86_64 .note.gnu.property or
3157	# compressed debug sections to x86_x32 properly:
3158	# https://github.com/ClangBuiltLinux/linux/issues/514
3159	# https://github.com/ClangBuiltLinux/linux/issues/1141
3160	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3161	help
3162	  Include code to run binaries for the x32 native 32-bit ABI
3163	  for 64-bit processors.  An x32 process gets access to the
3164	  full 64-bit register file and wide data path while leaving
3165	  pointers at 32 bits for smaller memory footprint.
3166
3167config COMPAT_32
3168	def_bool y
3169	depends on IA32_EMULATION || X86_32
3170	select HAVE_UID16
3171	select OLD_SIGSUSPEND3
3172
3173config COMPAT
3174	def_bool y
3175	depends on IA32_EMULATION || X86_X32_ABI
3176
3177config COMPAT_FOR_U64_ALIGNMENT
3178	def_bool y
3179	depends on COMPAT
3180
3181endmenu
3182
3183config HAVE_ATOMIC_IOMAP
3184	def_bool y
3185	depends on X86_32
3186
3187source "arch/x86/kvm/Kconfig"
3188
3189source "arch/x86/Kconfig.cpufeatures"
3190
3191source "arch/x86/Kconfig.assembler"
3192