xref: /linux/arch/x86/Kconfig (revision 785cdec46e9227f9433884ed3b436471e944007c)
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_64
431	default 3 if X86_PAE
432	default 2
433
434menu "Processor type and features"
435
436config SMP
437	bool "Symmetric multi-processing support"
438	help
439	  This enables support for systems with more than one CPU. If you have
440	  a system with only one CPU, say N. If you have a system with more
441	  than one CPU, say Y.
442
443	  If you say N here, the kernel will run on uni- and multiprocessor
444	  machines, but will use only one CPU of a multiprocessor machine. If
445	  you say Y here, the kernel will run on many, but not all,
446	  uniprocessor machines. On a uniprocessor machine, the kernel
447	  will run faster if you say N here.
448
449	  Note that if you say Y here and choose architecture "586" or
450	  "Pentium" under "Processor family", the kernel will not work on 486
451	  architectures. Similarly, multiprocessor kernels for the "PPro"
452	  architecture may not work on all Pentium based boards.
453
454	  People using multiprocessor machines who say Y here should also say
455	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
456	  Management" code will be disabled if you say Y here.
457
458	  See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
459	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
460	  <http://www.tldp.org/docs.html#howto>.
461
462	  If you don't know what to do here, say N.
463
464config X86_X2APIC
465	bool "x2APIC interrupt controller architecture support"
466	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
467	default y
468	help
469	  x2APIC is an interrupt controller architecture, a component of which
470	  (the local APIC) is present in the CPU. It allows faster access to
471	  the local APIC and supports a larger number of CPUs in the system
472	  than the predecessors.
473
474	  x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs
475	  in 2019, but it can be disabled by the BIOS. It is also frequently
476	  emulated in virtual machines, even when the host CPU does not support
477	  it. Support in the CPU can be checked by executing
478		grep x2apic /proc/cpuinfo
479
480	  If this configuration option is disabled, the kernel will boot with
481	  very reduced functionality and performance on some platforms that
482	  have x2APIC enabled. On the other hand, on hardware that does not
483	  support x2APIC, a kernel with this option enabled will just fallback
484	  to older APIC implementations.
485
486	  If in doubt, say Y.
487
488config X86_POSTED_MSI
489	bool "Enable MSI and MSI-x delivery by posted interrupts"
490	depends on X86_64 && IRQ_REMAP
491	help
492	  This enables MSIs that are under interrupt remapping to be delivered as
493	  posted interrupts to the host kernel. Interrupt throughput can
494	  potentially be improved by coalescing CPU notifications during high
495	  frequency bursts.
496
497	  If you don't know what to do here, say N.
498
499config X86_MPPARSE
500	bool "Enable MPS table" if ACPI
501	default y
502	depends on X86_LOCAL_APIC
503	help
504	  For old smp systems that do not have proper acpi support. Newer systems
505	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
506
507config X86_CPU_RESCTRL
508	bool "x86 CPU resource control support"
509	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
510	select KERNFS
511	select PROC_CPU_RESCTRL		if PROC_FS
512	select RESCTRL_FS_PSEUDO_LOCK
513	help
514	  Enable x86 CPU resource control support.
515
516	  Provide support for the allocation and monitoring of system resources
517	  usage by the CPU.
518
519	  Intel calls this Intel Resource Director Technology
520	  (Intel(R) RDT). More information about RDT can be found in the
521	  Intel x86 Architecture Software Developer Manual.
522
523	  AMD calls this AMD Platform Quality of Service (AMD QoS).
524	  More information about AMD QoS can be found in the AMD64 Technology
525	  Platform Quality of Service Extensions manual.
526
527	  Say N if unsure.
528
529config RESCTRL_FS_PSEUDO_LOCK
530	bool
531	help
532	  Software mechanism to pin data in a cache portion using
533	  micro-architecture specific knowledge.
534
535config X86_FRED
536	bool "Flexible Return and Event Delivery"
537	depends on X86_64
538	help
539	  When enabled, try to use Flexible Return and Event Delivery
540	  instead of the legacy SYSCALL/SYSENTER/IDT architecture for
541	  ring transitions and exception/interrupt handling if the
542	  system supports it.
543
544config X86_EXTENDED_PLATFORM
545	bool "Support for extended (non-PC) x86 platforms"
546	default y
547	help
548	  If you disable this option then the kernel will only support
549	  standard PC platforms. (which covers the vast majority of
550	  systems out there.)
551
552	  If you enable this option then you'll be able to select support
553	  for the following non-PC x86 platforms, depending on the value of
554	  CONFIG_64BIT.
555
556	  32-bit platforms (CONFIG_64BIT=n):
557		Goldfish (mostly Android emulator)
558		Intel CE media processor (CE4100) SoC
559		Intel Quark
560		RDC R-321x SoC
561
562	  64-bit platforms (CONFIG_64BIT=y):
563		Numascale NumaChip
564		ScaleMP vSMP
565		SGI Ultraviolet
566		Merrifield/Moorefield MID devices
567		Goldfish (mostly Android emulator)
568
569	  If you have one of these systems, or if you want to build a
570	  generic distribution kernel, say Y here - otherwise say N.
571
572# This is an alphabetically sorted list of 64 bit extended platforms
573# Please maintain the alphabetic order if and when there are additions
574config X86_NUMACHIP
575	bool "Numascale NumaChip"
576	depends on X86_64
577	depends on X86_EXTENDED_PLATFORM
578	depends on NUMA
579	depends on SMP
580	depends on X86_X2APIC
581	depends on PCI_MMCONFIG
582	help
583	  Adds support for Numascale NumaChip large-SMP systems. Needed to
584	  enable more than ~168 cores.
585	  If you don't have one of these, you should say N here.
586
587config X86_VSMP
588	bool "ScaleMP vSMP"
589	select HYPERVISOR_GUEST
590	select PARAVIRT
591	depends on X86_64 && PCI
592	depends on X86_EXTENDED_PLATFORM
593	depends on SMP
594	help
595	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
596	  supposed to run on these EM64T-based machines.  Only choose this option
597	  if you have one of these machines.
598
599config X86_UV
600	bool "SGI Ultraviolet"
601	depends on X86_64
602	depends on X86_EXTENDED_PLATFORM
603	depends on NUMA
604	depends on EFI
605	depends on KEXEC_CORE
606	depends on X86_X2APIC
607	depends on PCI
608	help
609	  This option is needed in order to support SGI Ultraviolet systems.
610	  If you don't have one of these, you should say N here.
611
612config X86_INTEL_MID
613	bool "Intel Z34xx/Z35xx MID platform support"
614	depends on X86_EXTENDED_PLATFORM
615	depends on X86_PLATFORM_DEVICES
616	depends on PCI
617	depends on X86_64 || (EXPERT && PCI_GOANY)
618	depends on X86_IO_APIC
619	select I2C
620	select DW_APB_TIMER
621	select INTEL_SCU_PCI
622	help
623	  Select to build a kernel capable of supporting 64-bit Intel MID
624	  (Mobile Internet Device) platform systems which do not have
625	  the PCI legacy interfaces.
626
627	  The only supported devices are the 22nm Merrified (Z34xx)
628	  and Moorefield (Z35xx) SoC used in the Intel Edison board and
629	  a small number of Android devices such as the Asus Zenfone 2,
630	  Asus FonePad 8 and Dell Venue 7.
631
632	  If you are building for a PC class system or non-MID tablet
633	  SoCs like Bay Trail (Z36xx/Z37xx), say N here.
634
635	  Intel MID platforms are based on an Intel processor and chipset which
636	  consume less power than most of the x86 derivatives.
637
638config X86_GOLDFISH
639	bool "Goldfish (Virtual Platform)"
640	depends on X86_EXTENDED_PLATFORM
641	help
642	  Enable support for the Goldfish virtual platform used primarily
643	  for Android development. Unless you are building for the Android
644	  Goldfish emulator say N here.
645
646# Following is an alphabetically sorted list of 32 bit extended platforms
647# Please maintain the alphabetic order if and when there are additions
648
649config X86_INTEL_CE
650	bool "CE4100 TV platform"
651	depends on PCI
652	depends on PCI_GODIRECT
653	depends on X86_IO_APIC
654	depends on X86_32
655	depends on X86_EXTENDED_PLATFORM
656	select X86_REBOOTFIXUPS
657	select OF
658	select OF_EARLY_FLATTREE
659	help
660	  Select for the Intel CE media processor (CE4100) SOC.
661	  This option compiles in support for the CE4100 SOC for settop
662	  boxes and media devices.
663
664config X86_INTEL_QUARK
665	bool "Intel Quark platform support"
666	depends on X86_32
667	depends on X86_EXTENDED_PLATFORM
668	depends on X86_PLATFORM_DEVICES
669	depends on X86_TSC
670	depends on PCI
671	depends on PCI_GOANY
672	depends on X86_IO_APIC
673	select IOSF_MBI
674	select INTEL_IMR
675	select COMMON_CLK
676	help
677	  Select to include support for Quark X1000 SoC.
678	  Say Y here if you have a Quark based system such as the Arduino
679	  compatible Intel Galileo.
680
681config X86_RDC321X
682	bool "RDC R-321x SoC"
683	depends on X86_32
684	depends on X86_EXTENDED_PLATFORM
685	select M486
686	select X86_REBOOTFIXUPS
687	help
688	  This option is needed for RDC R-321x system-on-chip, also known
689	  as R-8610-(G).
690	  If you don't have one of these chips, you should say N here.
691
692config X86_INTEL_LPSS
693	bool "Intel Low Power Subsystem Support"
694	depends on X86 && ACPI && PCI
695	select COMMON_CLK
696	select PINCTRL
697	select IOSF_MBI
698	help
699	  Select to build support for Intel Low Power Subsystem such as
700	  found on Intel Lynxpoint PCH. Selecting this option enables
701	  things like clock tree (common clock framework) and pincontrol
702	  which are needed by the LPSS peripheral drivers.
703
704config X86_AMD_PLATFORM_DEVICE
705	bool "AMD ACPI2Platform devices support"
706	depends on ACPI
707	select COMMON_CLK
708	select PINCTRL
709	help
710	  Select to interpret AMD specific ACPI device to platform device
711	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
712	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
713	  implemented under PINCTRL subsystem.
714
715config IOSF_MBI
716	tristate "Intel SoC IOSF Sideband support for SoC platforms"
717	depends on PCI
718	help
719	  This option enables sideband register access support for Intel SoC
720	  platforms. On these platforms the IOSF sideband is used in lieu of
721	  MSR's for some register accesses, mostly but not limited to thermal
722	  and power. Drivers may query the availability of this device to
723	  determine if they need the sideband in order to work on these
724	  platforms. The sideband is available on the following SoC products.
725	  This list is not meant to be exclusive.
726	   - BayTrail
727	   - Braswell
728	   - Quark
729
730	  You should say Y if you are running a kernel on one of these SoC's.
731
732config IOSF_MBI_DEBUG
733	bool "Enable IOSF sideband access through debugfs"
734	depends on IOSF_MBI && DEBUG_FS
735	help
736	  Select this option to expose the IOSF sideband access registers (MCR,
737	  MDR, MCRX) through debugfs to write and read register information from
738	  different units on the SoC. This is most useful for obtaining device
739	  state information for debug and analysis. As this is a general access
740	  mechanism, users of this option would have specific knowledge of the
741	  device they want to access.
742
743	  If you don't require the option or are in doubt, say N.
744
745config X86_SUPPORTS_MEMORY_FAILURE
746	def_bool y
747	# MCE code calls memory_failure():
748	depends on X86_MCE
749	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
750	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
751	depends on X86_64 || !SPARSEMEM
752	select ARCH_SUPPORTS_MEMORY_FAILURE
753
754config X86_32_IRIS
755	tristate "Eurobraille/Iris poweroff module"
756	depends on X86_32
757	help
758	  The Iris machines from EuroBraille do not have APM or ACPI support
759	  to shut themselves down properly.  A special I/O sequence is
760	  needed to do so, which is what this module does at
761	  kernel shutdown.
762
763	  This is only for Iris machines from EuroBraille.
764
765	  If unused, say N.
766
767config SCHED_OMIT_FRAME_POINTER
768	def_bool y
769	prompt "Single-depth WCHAN output"
770	depends on X86
771	help
772	  Calculate simpler /proc/<PID>/wchan values. If this option
773	  is disabled then wchan values will recurse back to the
774	  caller function. This provides more accurate wchan values,
775	  at the expense of slightly more scheduling overhead.
776
777	  If in doubt, say "Y".
778
779menuconfig HYPERVISOR_GUEST
780	bool "Linux guest support"
781	help
782	  Say Y here to enable options for running Linux under various hyper-
783	  visors. This option enables basic hypervisor detection and platform
784	  setup.
785
786	  If you say N, all options in this submenu will be skipped and
787	  disabled, and Linux guest support won't be built in.
788
789if HYPERVISOR_GUEST
790
791config PARAVIRT
792	bool "Enable paravirtualization code"
793	depends on HAVE_STATIC_CALL
794	help
795	  This changes the kernel so it can modify itself when it is run
796	  under a hypervisor, potentially improving performance significantly
797	  over full virtualization.  However, when run without a hypervisor
798	  the kernel is theoretically slower and slightly larger.
799
800config PARAVIRT_XXL
801	bool
802	depends on X86_64
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_DIRECT_GBPAGES
1468	def_bool y
1469	depends on X86_64
1470	help
1471	  Certain kernel features effectively disable kernel
1472	  linear 1 GB mappings (even if the CPU otherwise
1473	  supports them), so don't confuse the user by printing
1474	  that we have them enabled.
1475
1476config X86_CPA_STATISTICS
1477	bool "Enable statistic for Change Page Attribute"
1478	depends on DEBUG_FS
1479	help
1480	  Expose statistics about the Change Page Attribute mechanism, which
1481	  helps to determine the effectiveness of preserving large and huge
1482	  page mappings when mapping protections are changed.
1483
1484config X86_MEM_ENCRYPT
1485	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1486	select DYNAMIC_PHYSICAL_MASK
1487	def_bool n
1488
1489config AMD_MEM_ENCRYPT
1490	bool "AMD Secure Memory Encryption (SME) support"
1491	depends on X86_64 && CPU_SUP_AMD
1492	depends on EFI_STUB
1493	select DMA_COHERENT_POOL
1494	select ARCH_USE_MEMREMAP_PROT
1495	select INSTRUCTION_DECODER
1496	select ARCH_HAS_CC_PLATFORM
1497	select X86_MEM_ENCRYPT
1498	select UNACCEPTED_MEMORY
1499	select CRYPTO_LIB_AESGCM
1500	help
1501	  Say yes to enable support for the encryption of system memory.
1502	  This requires an AMD processor that supports Secure Memory
1503	  Encryption (SME).
1504
1505# Common NUMA Features
1506config NUMA
1507	bool "NUMA Memory Allocation and Scheduler Support"
1508	depends on SMP
1509	depends on X86_64
1510	select USE_PERCPU_NUMA_NODE_ID
1511	select OF_NUMA if OF
1512	help
1513	  Enable NUMA (Non-Uniform Memory Access) support.
1514
1515	  The kernel will try to allocate memory used by a CPU on the
1516	  local memory controller of the CPU and add some more
1517	  NUMA awareness to the kernel.
1518
1519	  For 64-bit this is recommended if the system is Intel Core i7
1520	  (or later), AMD Opteron, or EM64T NUMA.
1521
1522	  Otherwise, you should say N.
1523
1524config AMD_NUMA
1525	def_bool y
1526	prompt "Old style AMD Opteron NUMA detection"
1527	depends on X86_64 && NUMA && PCI
1528	help
1529	  Enable AMD NUMA node topology detection.  You should say Y here if
1530	  you have a multi processor AMD system. This uses an old method to
1531	  read the NUMA configuration directly from the builtin Northbridge
1532	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1533	  which also takes priority if both are compiled in.
1534
1535config X86_64_ACPI_NUMA
1536	def_bool y
1537	prompt "ACPI NUMA detection"
1538	depends on X86_64 && NUMA && ACPI && PCI
1539	select ACPI_NUMA
1540	help
1541	  Enable ACPI SRAT based node topology detection.
1542
1543config NODES_SHIFT
1544	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1545	range 1 10
1546	default "10" if MAXSMP
1547	default "6" if X86_64
1548	default "3"
1549	depends on NUMA
1550	help
1551	  Specify the maximum number of NUMA Nodes available on the target
1552	  system.  Increases memory reserved to accommodate various tables.
1553
1554config ARCH_FLATMEM_ENABLE
1555	def_bool y
1556	depends on X86_32 && !NUMA
1557
1558config ARCH_SPARSEMEM_ENABLE
1559	def_bool y
1560	select SPARSEMEM_STATIC if X86_32
1561	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1562	select SPARSEMEM_VMEMMAP if X86_64
1563
1564config ARCH_SPARSEMEM_DEFAULT
1565	def_bool X86_64 || (NUMA && X86_32)
1566
1567config ARCH_SELECT_MEMORY_MODEL
1568	def_bool y
1569	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1570
1571config ARCH_MEMORY_PROBE
1572	bool "Enable sysfs memory/probe interface"
1573	depends on MEMORY_HOTPLUG
1574	help
1575	  This option enables a sysfs memory/probe interface for testing.
1576	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1577	  If you are unsure how to answer this question, answer N.
1578
1579config ARCH_PROC_KCORE_TEXT
1580	def_bool y
1581	depends on X86_64 && PROC_KCORE
1582
1583config ILLEGAL_POINTER_VALUE
1584	hex
1585	default 0 if X86_32
1586	default 0xdead000000000000 if X86_64
1587
1588config X86_PMEM_LEGACY_DEVICE
1589	bool
1590
1591config X86_PMEM_LEGACY
1592	tristate "Support non-standard NVDIMMs and ADR protected memory"
1593	depends on PHYS_ADDR_T_64BIT
1594	depends on BLK_DEV
1595	select X86_PMEM_LEGACY_DEVICE
1596	select NUMA_KEEP_MEMINFO if NUMA
1597	select LIBNVDIMM
1598	help
1599	  Treat memory marked using the non-standard e820 type of 12 as used
1600	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1601	  The kernel will offer these regions to the 'pmem' driver so
1602	  they can be used for persistent storage.
1603
1604	  Say Y if unsure.
1605
1606config X86_CHECK_BIOS_CORRUPTION
1607	bool "Check for low memory corruption"
1608	help
1609	  Periodically check for memory corruption in low memory, which
1610	  is suspected to be caused by BIOS.  Even when enabled in the
1611	  configuration, it is disabled at runtime.  Enable it by
1612	  setting "memory_corruption_check=1" on the kernel command
1613	  line.  By default it scans the low 64k of memory every 60
1614	  seconds; see the memory_corruption_check_size and
1615	  memory_corruption_check_period parameters in
1616	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1617
1618	  When enabled with the default parameters, this option has
1619	  almost no overhead, as it reserves a relatively small amount
1620	  of memory and scans it infrequently.  It both detects corruption
1621	  and prevents it from affecting the running system.
1622
1623	  It is, however, intended as a diagnostic tool; if repeatable
1624	  BIOS-originated corruption always affects the same memory,
1625	  you can use memmap= to prevent the kernel from using that
1626	  memory.
1627
1628config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1629	bool "Set the default setting of memory_corruption_check"
1630	depends on X86_CHECK_BIOS_CORRUPTION
1631	default y
1632	help
1633	  Set whether the default state of memory_corruption_check is
1634	  on or off.
1635
1636config MATH_EMULATION
1637	bool
1638	depends on MODIFY_LDT_SYSCALL
1639	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1640	help
1641	  Linux can emulate a math coprocessor (used for floating point
1642	  operations) if you don't have one. 486DX and Pentium processors have
1643	  a math coprocessor built in, 486SX and 386 do not, unless you added
1644	  a 487DX or 387, respectively. (The messages during boot time can
1645	  give you some hints here ["man dmesg"].) Everyone needs either a
1646	  coprocessor or this emulation.
1647
1648	  If you don't have a math coprocessor, you need to say Y here; if you
1649	  say Y here even though you have a coprocessor, the coprocessor will
1650	  be used nevertheless. (This behavior can be changed with the kernel
1651	  command line option "no387", which comes handy if your coprocessor
1652	  is broken. Try "man bootparam" or see the documentation of your boot
1653	  loader (lilo or loadlin) about how to pass options to the kernel at
1654	  boot time.) This means that it is a good idea to say Y here if you
1655	  intend to use this kernel on different machines.
1656
1657	  More information about the internals of the Linux math coprocessor
1658	  emulation can be found in <file:arch/x86/math-emu/README>.
1659
1660	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1661	  kernel, it won't hurt.
1662
1663config MTRR
1664	def_bool y
1665	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1666	help
1667	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1668	  the Memory Type Range Registers (MTRRs) may be used to control
1669	  processor access to memory ranges. This is most useful if you have
1670	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1671	  allows bus write transfers to be combined into a larger transfer
1672	  before bursting over the PCI/AGP bus. This can increase performance
1673	  of image write operations 2.5 times or more. Saying Y here creates a
1674	  /proc/mtrr file which may be used to manipulate your processor's
1675	  MTRRs. Typically the X server should use this.
1676
1677	  This code has a reasonably generic interface so that similar
1678	  control registers on other processors can be easily supported
1679	  as well:
1680
1681	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1682	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1683	  these, the ARRs are used to emulate the MTRRs.
1684	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1685	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1686	  write-combining. All of these processors are supported by this code
1687	  and it makes sense to say Y here if you have one of them.
1688
1689	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1690	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1691	  can lead to all sorts of problems, so it's good to say Y here.
1692
1693	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1694	  just add about 9 KB to your kernel.
1695
1696	  See <file:Documentation/arch/x86/mtrr.rst> for more information.
1697
1698config MTRR_SANITIZER
1699	def_bool y
1700	prompt "MTRR cleanup support"
1701	depends on MTRR
1702	help
1703	  Convert MTRR layout from continuous to discrete, so X drivers can
1704	  add writeback entries.
1705
1706	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1707	  The largest mtrr entry size for a continuous block can be set with
1708	  mtrr_chunk_size.
1709
1710	  If unsure, say Y.
1711
1712config MTRR_SANITIZER_ENABLE_DEFAULT
1713	int "MTRR cleanup enable value (0-1)"
1714	range 0 1
1715	default "0"
1716	depends on MTRR_SANITIZER
1717	help
1718	  Enable mtrr cleanup default value
1719
1720config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1721	int "MTRR cleanup spare reg num (0-7)"
1722	range 0 7
1723	default "1"
1724	depends on MTRR_SANITIZER
1725	help
1726	  mtrr cleanup spare entries default, it can be changed via
1727	  mtrr_spare_reg_nr=N on the kernel command line.
1728
1729config X86_PAT
1730	def_bool y
1731	prompt "x86 PAT support" if EXPERT
1732	depends on MTRR
1733	select ARCH_USES_PG_ARCH_2
1734	help
1735	  Use PAT attributes to setup page level cache control.
1736
1737	  PATs are the modern equivalents of MTRRs and are much more
1738	  flexible than MTRRs.
1739
1740	  Say N here if you see bootup problems (boot crash, boot hang,
1741	  spontaneous reboots) or a non-working video driver.
1742
1743	  If unsure, say Y.
1744
1745config X86_UMIP
1746	def_bool y
1747	prompt "User Mode Instruction Prevention" if EXPERT
1748	help
1749	  User Mode Instruction Prevention (UMIP) is a security feature in
1750	  some x86 processors. If enabled, a general protection fault is
1751	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1752	  executed in user mode. These instructions unnecessarily expose
1753	  information about the hardware state.
1754
1755	  The vast majority of applications do not use these instructions.
1756	  For the very few that do, software emulation is provided in
1757	  specific cases in protected and virtual-8086 modes. Emulated
1758	  results are dummy.
1759
1760config CC_HAS_IBT
1761	# GCC >= 9 and binutils >= 2.29
1762	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1763	# Clang/LLVM >= 14
1764	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1765	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1766	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1767		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1768		  $(as-instr,endbr64)
1769
1770config X86_CET
1771	def_bool n
1772	help
1773	  CET features configured (Shadow stack or IBT)
1774
1775config X86_KERNEL_IBT
1776	prompt "Indirect Branch Tracking"
1777	def_bool y
1778	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1779	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1780	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1781	select OBJTOOL
1782	select X86_CET
1783	help
1784	  Build the kernel with support for Indirect Branch Tracking, a
1785	  hardware support course-grain forward-edge Control Flow Integrity
1786	  protection. It enforces that all indirect calls must land on
1787	  an ENDBR instruction, as such, the compiler will instrument the
1788	  code with them to make this happen.
1789
1790	  In addition to building the kernel with IBT, seal all functions that
1791	  are not indirect call targets, avoiding them ever becoming one.
1792
1793	  This requires LTO like objtool runs and will slow down the build. It
1794	  does significantly reduce the number of ENDBR instructions in the
1795	  kernel image.
1796
1797config X86_INTEL_MEMORY_PROTECTION_KEYS
1798	prompt "Memory Protection Keys"
1799	def_bool y
1800	# Note: only available in 64-bit mode
1801	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1802	select ARCH_USES_HIGH_VMA_FLAGS
1803	select ARCH_HAS_PKEYS
1804	help
1805	  Memory Protection Keys provides a mechanism for enforcing
1806	  page-based protections, but without requiring modification of the
1807	  page tables when an application changes protection domains.
1808
1809	  For details, see Documentation/core-api/protection-keys.rst
1810
1811	  If unsure, say y.
1812
1813config ARCH_PKEY_BITS
1814	int
1815	default 4
1816
1817choice
1818	prompt "TSX enable mode"
1819	depends on CPU_SUP_INTEL
1820	default X86_INTEL_TSX_MODE_OFF
1821	help
1822	  Intel's TSX (Transactional Synchronization Extensions) feature
1823	  allows to optimize locking protocols through lock elision which
1824	  can lead to a noticeable performance boost.
1825
1826	  On the other hand it has been shown that TSX can be exploited
1827	  to form side channel attacks (e.g. TAA) and chances are there
1828	  will be more of those attacks discovered in the future.
1829
1830	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1831	  might override this decision by tsx=on the command line parameter.
1832	  Even with TSX enabled, the kernel will attempt to enable the best
1833	  possible TAA mitigation setting depending on the microcode available
1834	  for the particular machine.
1835
1836	  This option allows to set the default tsx mode between tsx=on, =off
1837	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1838	  details.
1839
1840	  Say off if not sure, auto if TSX is in use but it should be used on safe
1841	  platforms or on if TSX is in use and the security aspect of tsx is not
1842	  relevant.
1843
1844config X86_INTEL_TSX_MODE_OFF
1845	bool "off"
1846	help
1847	  TSX is disabled if possible - equals to tsx=off command line parameter.
1848
1849config X86_INTEL_TSX_MODE_ON
1850	bool "on"
1851	help
1852	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1853	  line parameter.
1854
1855config X86_INTEL_TSX_MODE_AUTO
1856	bool "auto"
1857	help
1858	  TSX is enabled on TSX capable HW that is believed to be safe against
1859	  side channel attacks- equals the tsx=auto command line parameter.
1860endchoice
1861
1862config X86_SGX
1863	bool "Software Guard eXtensions (SGX)"
1864	depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1865	depends on CRYPTO=y
1866	depends on CRYPTO_SHA256=y
1867	select MMU_NOTIFIER
1868	select NUMA_KEEP_MEMINFO if NUMA
1869	select XARRAY_MULTI
1870	help
1871	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1872	  that can be used by applications to set aside private regions of code
1873	  and data, referred to as enclaves. An enclave's private memory can
1874	  only be accessed by code running within the enclave. Accesses from
1875	  outside the enclave, including other enclaves, are disallowed by
1876	  hardware.
1877
1878	  If unsure, say N.
1879
1880config X86_USER_SHADOW_STACK
1881	bool "X86 userspace shadow stack"
1882	depends on AS_WRUSS
1883	depends on X86_64
1884	select ARCH_USES_HIGH_VMA_FLAGS
1885	select ARCH_HAS_USER_SHADOW_STACK
1886	select X86_CET
1887	help
1888	  Shadow stack protection is a hardware feature that detects function
1889	  return address corruption.  This helps mitigate ROP attacks.
1890	  Applications must be enabled to use it, and old userspace does not
1891	  get protection "for free".
1892
1893	  CPUs supporting shadow stacks were first released in 2020.
1894
1895	  See Documentation/arch/x86/shstk.rst for more information.
1896
1897	  If unsure, say N.
1898
1899config INTEL_TDX_HOST
1900	bool "Intel Trust Domain Extensions (TDX) host support"
1901	depends on CPU_SUP_INTEL
1902	depends on X86_64
1903	depends on KVM_INTEL
1904	depends on X86_X2APIC
1905	select ARCH_KEEP_MEMBLOCK
1906	depends on CONTIG_ALLOC
1907	depends on !KEXEC_CORE
1908	depends on X86_MCE
1909	help
1910	  Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1911	  host and certain physical attacks.  This option enables necessary TDX
1912	  support in the host kernel to run confidential VMs.
1913
1914	  If unsure, say N.
1915
1916config EFI
1917	bool "EFI runtime service support"
1918	depends on ACPI
1919	select UCS2_STRING
1920	select EFI_RUNTIME_WRAPPERS
1921	select ARCH_USE_MEMREMAP_PROT
1922	select EFI_RUNTIME_MAP if KEXEC_CORE
1923	help
1924	  This enables the kernel to use EFI runtime services that are
1925	  available (such as the EFI variable services).
1926
1927	  This option is only useful on systems that have EFI firmware.
1928	  In addition, you should use the latest ELILO loader available
1929	  at <http://elilo.sourceforge.net> in order to take advantage
1930	  of EFI runtime services. However, even with this option, the
1931	  resultant kernel should continue to boot on existing non-EFI
1932	  platforms.
1933
1934config EFI_STUB
1935	bool "EFI stub support"
1936	depends on EFI
1937	select RELOCATABLE
1938	help
1939	  This kernel feature allows a bzImage to be loaded directly
1940	  by EFI firmware without the use of a bootloader.
1941
1942	  See Documentation/admin-guide/efi-stub.rst for more information.
1943
1944config EFI_HANDOVER_PROTOCOL
1945	bool "EFI handover protocol (DEPRECATED)"
1946	depends on EFI_STUB
1947	default y
1948	help
1949	  Select this in order to include support for the deprecated EFI
1950	  handover protocol, which defines alternative entry points into the
1951	  EFI stub.  This is a practice that has no basis in the UEFI
1952	  specification, and requires a priori knowledge on the part of the
1953	  bootloader about Linux/x86 specific ways of passing the command line
1954	  and initrd, and where in memory those assets may be loaded.
1955
1956	  If in doubt, say Y. Even though the corresponding support is not
1957	  present in upstream GRUB or other bootloaders, most distros build
1958	  GRUB with numerous downstream patches applied, and may rely on the
1959	  handover protocol as as result.
1960
1961config EFI_MIXED
1962	bool "EFI mixed-mode support"
1963	depends on EFI_STUB && X86_64
1964	help
1965	  Enabling this feature allows a 64-bit kernel to be booted
1966	  on a 32-bit firmware, provided that your CPU supports 64-bit
1967	  mode.
1968
1969	  Note that it is not possible to boot a mixed-mode enabled
1970	  kernel via the EFI boot stub - a bootloader that supports
1971	  the EFI handover protocol must be used.
1972
1973	  If unsure, say N.
1974
1975config EFI_RUNTIME_MAP
1976	bool "Export EFI runtime maps to sysfs" if EXPERT
1977	depends on EFI
1978	help
1979	  Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
1980	  That memory map is required by the 2nd kernel to set up EFI virtual
1981	  mappings after kexec, but can also be used for debugging purposes.
1982
1983	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
1984
1985source "kernel/Kconfig.hz"
1986
1987config ARCH_SUPPORTS_KEXEC
1988	def_bool y
1989
1990config ARCH_SUPPORTS_KEXEC_FILE
1991	def_bool X86_64
1992
1993config ARCH_SELECTS_KEXEC_FILE
1994	def_bool y
1995	depends on KEXEC_FILE
1996	select HAVE_IMA_KEXEC if IMA
1997
1998config ARCH_SUPPORTS_KEXEC_PURGATORY
1999	def_bool y
2000
2001config ARCH_SUPPORTS_KEXEC_SIG
2002	def_bool y
2003
2004config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2005	def_bool y
2006
2007config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2008	def_bool y
2009
2010config ARCH_SUPPORTS_KEXEC_JUMP
2011	def_bool y
2012
2013config ARCH_SUPPORTS_CRASH_DUMP
2014	def_bool X86_64 || (X86_32 && HIGHMEM)
2015
2016config ARCH_DEFAULT_CRASH_DUMP
2017	def_bool y
2018
2019config ARCH_SUPPORTS_CRASH_HOTPLUG
2020	def_bool y
2021
2022config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2023	def_bool CRASH_RESERVE
2024
2025config PHYSICAL_START
2026	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2027	default "0x1000000"
2028	help
2029	  This gives the physical address where the kernel is loaded.
2030
2031	  If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2032	  will decompress itself to above physical address and run from there.
2033	  Otherwise, bzImage will run from the address where it has been loaded
2034	  by the boot loader. The only exception is if it is loaded below the
2035	  above physical address, in which case it will relocate itself there.
2036
2037	  In normal kdump cases one does not have to set/change this option
2038	  as now bzImage can be compiled as a completely relocatable image
2039	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2040	  address. This option is mainly useful for the folks who don't want
2041	  to use a bzImage for capturing the crash dump and want to use a
2042	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2043	  to be specifically compiled to run from a specific memory area
2044	  (normally a reserved region) and this option comes handy.
2045
2046	  So if you are using bzImage for capturing the crash dump,
2047	  leave the value here unchanged to 0x1000000 and set
2048	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2049	  for capturing the crash dump change this value to start of
2050	  the reserved region.  In other words, it can be set based on
2051	  the "X" value as specified in the "crashkernel=YM@XM"
2052	  command line boot parameter passed to the panic-ed
2053	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2054	  for more details about crash dumps.
2055
2056	  Usage of bzImage for capturing the crash dump is recommended as
2057	  one does not have to build two kernels. Same kernel can be used
2058	  as production kernel and capture kernel. Above option should have
2059	  gone away after relocatable bzImage support is introduced. But it
2060	  is present because there are users out there who continue to use
2061	  vmlinux for dump capture. This option should go away down the
2062	  line.
2063
2064	  Don't change this unless you know what you are doing.
2065
2066config RELOCATABLE
2067	bool "Build a relocatable kernel"
2068	default y
2069	help
2070	  This builds a kernel image that retains relocation information
2071	  so it can be loaded someplace besides the default 1MB.
2072	  The relocations tend to make the kernel binary about 10% larger,
2073	  but are discarded at runtime.
2074
2075	  One use is for the kexec on panic case where the recovery kernel
2076	  must live at a different physical address than the primary
2077	  kernel.
2078
2079	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2080	  it has been loaded at and the compile time physical address
2081	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2082
2083config RANDOMIZE_BASE
2084	bool "Randomize the address of the kernel image (KASLR)"
2085	depends on RELOCATABLE
2086	default y
2087	help
2088	  In support of Kernel Address Space Layout Randomization (KASLR),
2089	  this randomizes the physical address at which the kernel image
2090	  is decompressed and the virtual address where the kernel
2091	  image is mapped, as a security feature that deters exploit
2092	  attempts relying on knowledge of the location of kernel
2093	  code internals.
2094
2095	  On 64-bit, the kernel physical and virtual addresses are
2096	  randomized separately. The physical address will be anywhere
2097	  between 16MB and the top of physical memory (up to 64TB). The
2098	  virtual address will be randomized from 16MB up to 1GB (9 bits
2099	  of entropy). Note that this also reduces the memory space
2100	  available to kernel modules from 1.5GB to 1GB.
2101
2102	  On 32-bit, the kernel physical and virtual addresses are
2103	  randomized together. They will be randomized from 16MB up to
2104	  512MB (8 bits of entropy).
2105
2106	  Entropy is generated using the RDRAND instruction if it is
2107	  supported. If RDTSC is supported, its value is mixed into
2108	  the entropy pool as well. If neither RDRAND nor RDTSC are
2109	  supported, then entropy is read from the i8254 timer. The
2110	  usable entropy is limited by the kernel being built using
2111	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2112	  minimum of 2MB. As a result, only 10 bits of entropy are
2113	  theoretically possible, but the implementations are further
2114	  limited due to memory layouts.
2115
2116	  If unsure, say Y.
2117
2118# Relocation on x86 needs some additional build support
2119config X86_NEED_RELOCS
2120	def_bool y
2121	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2122	select ARCH_VMLINUX_NEEDS_RELOCS
2123
2124config PHYSICAL_ALIGN
2125	hex "Alignment value to which kernel should be aligned"
2126	default "0x200000"
2127	range 0x2000 0x1000000 if X86_32
2128	range 0x200000 0x1000000 if X86_64
2129	help
2130	  This value puts the alignment restrictions on physical address
2131	  where kernel is loaded and run from. Kernel is compiled for an
2132	  address which meets above alignment restriction.
2133
2134	  If bootloader loads the kernel at a non-aligned address and
2135	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2136	  address aligned to above value and run from there.
2137
2138	  If bootloader loads the kernel at a non-aligned address and
2139	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2140	  load address and decompress itself to the address it has been
2141	  compiled for and run from there. The address for which kernel is
2142	  compiled already meets above alignment restrictions. Hence the
2143	  end result is that kernel runs from a physical address meeting
2144	  above alignment restrictions.
2145
2146	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2147	  this value must be a multiple of 0x200000.
2148
2149	  Don't change this unless you know what you are doing.
2150
2151config RANDOMIZE_MEMORY
2152	bool "Randomize the kernel memory sections"
2153	depends on X86_64
2154	depends on RANDOMIZE_BASE
2155	default RANDOMIZE_BASE
2156	help
2157	  Randomizes the base virtual address of kernel memory sections
2158	  (physical memory mapping, vmalloc & vmemmap). This security feature
2159	  makes exploits relying on predictable memory locations less reliable.
2160
2161	  The order of allocations remains unchanged. Entropy is generated in
2162	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2163	  configuration have in average 30,000 different possible virtual
2164	  addresses for each memory section.
2165
2166	  If unsure, say Y.
2167
2168config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2169	hex "Physical memory mapping padding" if EXPERT
2170	depends on RANDOMIZE_MEMORY
2171	default "0xa" if MEMORY_HOTPLUG
2172	default "0x0"
2173	range 0x1 0x40 if MEMORY_HOTPLUG
2174	range 0x0 0x40
2175	help
2176	  Define the padding in terabytes added to the existing physical
2177	  memory size during kernel memory randomization. It is useful
2178	  for memory hotplug support but reduces the entropy available for
2179	  address randomization.
2180
2181	  If unsure, leave at the default value.
2182
2183config ADDRESS_MASKING
2184	bool "Linear Address Masking support"
2185	depends on X86_64
2186	depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
2187	help
2188	  Linear Address Masking (LAM) modifies the checking that is applied
2189	  to 64-bit linear addresses, allowing software to use of the
2190	  untranslated address bits for metadata.
2191
2192	  The capability can be used for efficient address sanitizers (ASAN)
2193	  implementation and for optimizations in JITs.
2194
2195config HOTPLUG_CPU
2196	def_bool y
2197	depends on SMP
2198
2199config COMPAT_VDSO
2200	def_bool n
2201	prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)"
2202	depends on COMPAT_32
2203	help
2204	  Certain buggy versions of glibc will crash if they are
2205	  presented with a 32-bit vDSO that is not mapped at the address
2206	  indicated in its segment table.
2207
2208	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2209	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2210	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2211	  the only released version with the bug, but OpenSUSE 9
2212	  contains a buggy "glibc 2.3.2".
2213
2214	  The symptom of the bug is that everything crashes on startup, saying:
2215	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2216
2217	  Saying Y here changes the default value of the vdso32 boot
2218	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2219	  This works around the glibc bug but hurts performance.
2220
2221	  If unsure, say N: if you are compiling your own kernel, you
2222	  are unlikely to be using a buggy version of glibc.
2223
2224choice
2225	prompt "vsyscall table for legacy applications"
2226	depends on X86_64
2227	default LEGACY_VSYSCALL_XONLY
2228	help
2229	  Legacy user code that does not know how to find the vDSO expects
2230	  to be able to issue three syscalls by calling fixed addresses in
2231	  kernel space. Since this location is not randomized with ASLR,
2232	  it can be used to assist security vulnerability exploitation.
2233
2234	  This setting can be changed at boot time via the kernel command
2235	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2236	  is deprecated and can only be enabled using the kernel command
2237	  line.
2238
2239	  On a system with recent enough glibc (2.14 or newer) and no
2240	  static binaries, you can say None without a performance penalty
2241	  to improve security.
2242
2243	  If unsure, select "Emulate execution only".
2244
2245	config LEGACY_VSYSCALL_XONLY
2246		bool "Emulate execution only"
2247		help
2248		  The kernel traps and emulates calls into the fixed vsyscall
2249		  address mapping and does not allow reads.  This
2250		  configuration is recommended when userspace might use the
2251		  legacy vsyscall area but support for legacy binary
2252		  instrumentation of legacy code is not needed.  It mitigates
2253		  certain uses of the vsyscall area as an ASLR-bypassing
2254		  buffer.
2255
2256	config LEGACY_VSYSCALL_NONE
2257		bool "None"
2258		help
2259		  There will be no vsyscall mapping at all. This will
2260		  eliminate any risk of ASLR bypass due to the vsyscall
2261		  fixed address mapping. Attempts to use the vsyscalls
2262		  will be reported to dmesg, so that either old or
2263		  malicious userspace programs can be identified.
2264
2265endchoice
2266
2267config CMDLINE_BOOL
2268	bool "Built-in kernel command line"
2269	help
2270	  Allow for specifying boot arguments to the kernel at
2271	  build time.  On some systems (e.g. embedded ones), it is
2272	  necessary or convenient to provide some or all of the
2273	  kernel boot arguments with the kernel itself (that is,
2274	  to not rely on the boot loader to provide them.)
2275
2276	  To compile command line arguments into the kernel,
2277	  set this option to 'Y', then fill in the
2278	  boot arguments in CONFIG_CMDLINE.
2279
2280	  Systems with fully functional boot loaders (i.e. non-embedded)
2281	  should leave this option set to 'N'.
2282
2283config CMDLINE
2284	string "Built-in kernel command string"
2285	depends on CMDLINE_BOOL
2286	default ""
2287	help
2288	  Enter arguments here that should be compiled into the kernel
2289	  image and used at boot time.  If the boot loader provides a
2290	  command line at boot time, it is appended to this string to
2291	  form the full kernel command line, when the system boots.
2292
2293	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2294	  change this behavior.
2295
2296	  In most cases, the command line (whether built-in or provided
2297	  by the boot loader) should specify the device for the root
2298	  file system.
2299
2300config CMDLINE_OVERRIDE
2301	bool "Built-in command line overrides boot loader arguments"
2302	depends on CMDLINE_BOOL && CMDLINE != ""
2303	help
2304	  Set this option to 'Y' to have the kernel ignore the boot loader
2305	  command line, and use ONLY the built-in command line.
2306
2307	  This is used to work around broken boot loaders.  This should
2308	  be set to 'N' under normal conditions.
2309
2310config MODIFY_LDT_SYSCALL
2311	bool "Enable the LDT (local descriptor table)" if EXPERT
2312	default y
2313	help
2314	  Linux can allow user programs to install a per-process x86
2315	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2316	  call.  This is required to run 16-bit or segmented code such as
2317	  DOSEMU or some Wine programs.  It is also used by some very old
2318	  threading libraries.
2319
2320	  Enabling this feature adds a small amount of overhead to
2321	  context switches and increases the low-level kernel attack
2322	  surface.  Disabling it removes the modify_ldt(2) system call.
2323
2324	  Saying 'N' here may make sense for embedded or server kernels.
2325
2326config STRICT_SIGALTSTACK_SIZE
2327	bool "Enforce strict size checking for sigaltstack"
2328	depends on DYNAMIC_SIGFRAME
2329	help
2330	  For historical reasons MINSIGSTKSZ is a constant which became
2331	  already too small with AVX512 support. Add a mechanism to
2332	  enforce strict checking of the sigaltstack size against the
2333	  real size of the FPU frame. This option enables the check
2334	  by default. It can also be controlled via the kernel command
2335	  line option 'strict_sas_size' independent of this config
2336	  switch. Enabling it might break existing applications which
2337	  allocate a too small sigaltstack but 'work' because they
2338	  never get a signal delivered.
2339
2340	  Say 'N' unless you want to really enforce this check.
2341
2342config CFI_AUTO_DEFAULT
2343	bool "Attempt to use FineIBT by default at boot time"
2344	depends on FINEIBT
2345	depends on !RUST || RUSTC_VERSION >= 108800
2346	default y
2347	help
2348	  Attempt to use FineIBT by default at boot time. If enabled,
2349	  this is the same as booting with "cfi=auto". If disabled,
2350	  this is the same as booting with "cfi=kcfi".
2351
2352source "kernel/livepatch/Kconfig"
2353
2354config X86_BUS_LOCK_DETECT
2355	bool "Split Lock Detect and Bus Lock Detect support"
2356	depends on CPU_SUP_INTEL || CPU_SUP_AMD
2357	default y
2358	help
2359	  Enable Split Lock Detect and Bus Lock Detect functionalities.
2360	  See <file:Documentation/arch/x86/buslock.rst> for more information.
2361
2362endmenu
2363
2364config CC_HAS_NAMED_AS
2365	def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
2366	depends on CC_IS_GCC
2367
2368#
2369# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN)
2370# are incompatible with named address spaces with GCC < 13.3
2371# (see GCC PR sanitizer/111736 and also PR sanitizer/115172).
2372#
2373
2374config CC_HAS_NAMED_AS_FIXED_SANITIZERS
2375	def_bool y
2376	depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300
2377	depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200
2378
2379config USE_X86_SEG_SUPPORT
2380	def_bool CC_HAS_NAMED_AS
2381	depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS
2382
2383config CC_HAS_SLS
2384	def_bool $(cc-option,-mharden-sls=all)
2385
2386config CC_HAS_RETURN_THUNK
2387	def_bool $(cc-option,-mfunction-return=thunk-extern)
2388
2389config CC_HAS_ENTRY_PADDING
2390	def_bool $(cc-option,-fpatchable-function-entry=16,16)
2391
2392config CC_HAS_KCFI_ARITY
2393	def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity)
2394	depends on CC_IS_CLANG && !RUST
2395
2396config FUNCTION_PADDING_CFI
2397	int
2398	default 59 if FUNCTION_ALIGNMENT_64B
2399	default 27 if FUNCTION_ALIGNMENT_32B
2400	default 11 if FUNCTION_ALIGNMENT_16B
2401	default  3 if FUNCTION_ALIGNMENT_8B
2402	default  0
2403
2404# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2405# except Kconfig can't do arithmetic :/
2406config FUNCTION_PADDING_BYTES
2407	int
2408	default FUNCTION_PADDING_CFI if CFI_CLANG
2409	default FUNCTION_ALIGNMENT
2410
2411config CALL_PADDING
2412	def_bool n
2413	depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2414	select FUNCTION_ALIGNMENT_16B
2415
2416config FINEIBT
2417	def_bool y
2418	depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2419	select CALL_PADDING
2420
2421config FINEIBT_BHI
2422	def_bool y
2423	depends on FINEIBT && CC_HAS_KCFI_ARITY
2424
2425config HAVE_CALL_THUNKS
2426	def_bool y
2427	depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2428
2429config CALL_THUNKS
2430	def_bool n
2431	select CALL_PADDING
2432
2433config PREFIX_SYMBOLS
2434	def_bool y
2435	depends on CALL_PADDING && !CFI_CLANG
2436
2437menuconfig CPU_MITIGATIONS
2438	bool "Mitigations for CPU vulnerabilities"
2439	default y
2440	help
2441	  Say Y here to enable options which enable mitigations for hardware
2442	  vulnerabilities (usually related to speculative execution).
2443	  Mitigations can be disabled or restricted to SMT systems at runtime
2444	  via the "mitigations" kernel parameter.
2445
2446	  If you say N, all mitigations will be disabled.  This CANNOT be
2447	  overridden at runtime.
2448
2449	  Say 'Y', unless you really know what you are doing.
2450
2451if CPU_MITIGATIONS
2452
2453config MITIGATION_PAGE_TABLE_ISOLATION
2454	bool "Remove the kernel mapping in user mode"
2455	default y
2456	depends on (X86_64 || X86_PAE)
2457	help
2458	  This feature reduces the number of hardware side channels by
2459	  ensuring that the majority of kernel addresses are not mapped
2460	  into userspace.
2461
2462	  See Documentation/arch/x86/pti.rst for more details.
2463
2464config MITIGATION_RETPOLINE
2465	bool "Avoid speculative indirect branches in kernel"
2466	select OBJTOOL if HAVE_OBJTOOL
2467	default y
2468	help
2469	  Compile kernel with the retpoline compiler options to guard against
2470	  kernel-to-user data leaks by avoiding speculative indirect
2471	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2472	  support for full protection. The kernel may run slower.
2473
2474config MITIGATION_RETHUNK
2475	bool "Enable return-thunks"
2476	depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2477	select OBJTOOL if HAVE_OBJTOOL
2478	default y if X86_64
2479	help
2480	  Compile the kernel with the return-thunks compiler option to guard
2481	  against kernel-to-user data leaks by avoiding return speculation.
2482	  Requires a compiler with -mfunction-return=thunk-extern
2483	  support for full protection. The kernel may run slower.
2484
2485config MITIGATION_UNRET_ENTRY
2486	bool "Enable UNRET on kernel entry"
2487	depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2488	default y
2489	help
2490	  Compile the kernel with support for the retbleed=unret mitigation.
2491
2492config MITIGATION_CALL_DEPTH_TRACKING
2493	bool "Mitigate RSB underflow with call depth tracking"
2494	depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2495	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2496	select CALL_THUNKS
2497	default y
2498	help
2499	  Compile the kernel with call depth tracking to mitigate the Intel
2500	  SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off
2501	  by default and needs to be enabled on the kernel command line via the
2502	  retbleed=stuff option. For non-affected systems the overhead of this
2503	  option is marginal as the call depth tracking is using run-time
2504	  generated call thunks in a compiler generated padding area and call
2505	  patching. This increases text size by ~5%. For non affected systems
2506	  this space is unused. On affected SKL systems this results in a
2507	  significant performance gain over the IBRS mitigation.
2508
2509config CALL_THUNKS_DEBUG
2510	bool "Enable call thunks and call depth tracking debugging"
2511	depends on MITIGATION_CALL_DEPTH_TRACKING
2512	select FUNCTION_ALIGNMENT_32B
2513	default n
2514	help
2515	  Enable call/ret counters for imbalance detection and build in
2516	  a noisy dmesg about callthunks generation and call patching for
2517	  trouble shooting. The debug prints need to be enabled on the
2518	  kernel command line with 'debug-callthunks'.
2519	  Only enable this when you are debugging call thunks as this
2520	  creates a noticeable runtime overhead. If unsure say N.
2521
2522config MITIGATION_IBPB_ENTRY
2523	bool "Enable IBPB on kernel entry"
2524	depends on CPU_SUP_AMD && X86_64
2525	default y
2526	help
2527	  Compile the kernel with support for the retbleed=ibpb and
2528	  spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations.
2529
2530config MITIGATION_IBRS_ENTRY
2531	bool "Enable IBRS on kernel entry"
2532	depends on CPU_SUP_INTEL && X86_64
2533	default y
2534	help
2535	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2536	  This mitigates both spectre_v2 and retbleed at great cost to
2537	  performance.
2538
2539config MITIGATION_SRSO
2540	bool "Mitigate speculative RAS overflow on AMD"
2541	depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2542	default y
2543	help
2544	  Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2545
2546config MITIGATION_SLS
2547	bool "Mitigate Straight-Line-Speculation"
2548	depends on CC_HAS_SLS && X86_64
2549	select OBJTOOL if HAVE_OBJTOOL
2550	default n
2551	help
2552	  Compile the kernel with straight-line-speculation options to guard
2553	  against straight line speculation. The kernel image might be slightly
2554	  larger.
2555
2556config MITIGATION_GDS
2557	bool "Mitigate Gather Data Sampling"
2558	depends on CPU_SUP_INTEL
2559	default y
2560	help
2561	  Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
2562	  vulnerability which allows unprivileged speculative access to data
2563	  which was previously stored in vector registers. The attacker uses gather
2564	  instructions to infer the stale vector register data.
2565
2566config MITIGATION_RFDS
2567	bool "RFDS Mitigation"
2568	depends on CPU_SUP_INTEL
2569	default y
2570	help
2571	  Enable mitigation for Register File Data Sampling (RFDS) by default.
2572	  RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2573	  allows unprivileged speculative access to stale data previously
2574	  stored in floating point, vector and integer registers.
2575	  See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2576
2577config MITIGATION_SPECTRE_BHI
2578	bool "Mitigate Spectre-BHB (Branch History Injection)"
2579	depends on CPU_SUP_INTEL
2580	default y
2581	help
2582	  Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2583	  where the branch history buffer is poisoned to speculatively steer
2584	  indirect branches.
2585	  See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2586
2587config MITIGATION_MDS
2588	bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
2589	depends on CPU_SUP_INTEL
2590	default y
2591	help
2592	  Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
2593	  a hardware vulnerability which allows unprivileged speculative access
2594	  to data which is available in various CPU internal buffers.
2595	  See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
2596
2597config MITIGATION_TAA
2598	bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
2599	depends on CPU_SUP_INTEL
2600	default y
2601	help
2602	  Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
2603	  vulnerability that allows unprivileged speculative access to data
2604	  which is available in various CPU internal buffers by using
2605	  asynchronous aborts within an Intel TSX transactional region.
2606	  See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
2607
2608config MITIGATION_MMIO_STALE_DATA
2609	bool "Mitigate MMIO Stale Data hardware bug"
2610	depends on CPU_SUP_INTEL
2611	default y
2612	help
2613	  Enable mitigation for MMIO Stale Data hardware bugs.  Processor MMIO
2614	  Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
2615	  vulnerabilities that can expose data. The vulnerabilities require the
2616	  attacker to have access to MMIO.
2617	  See also
2618	  <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
2619
2620config MITIGATION_L1TF
2621	bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
2622	depends on CPU_SUP_INTEL
2623	default y
2624	help
2625	  Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
2626	  hardware vulnerability which allows unprivileged speculative access to data
2627	  available in the Level 1 Data Cache.
2628	  See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
2629
2630config MITIGATION_RETBLEED
2631	bool "Mitigate RETBleed hardware bug"
2632	depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
2633	default y
2634	help
2635	  Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
2636	  with Return Instructions) vulnerability.  RETBleed is a speculative
2637	  execution attack which takes advantage of microarchitectural behavior
2638	  in many modern microprocessors, similar to Spectre v2. An
2639	  unprivileged attacker can use these flaws to bypass conventional
2640	  memory security restrictions to gain read access to privileged memory
2641	  that would otherwise be inaccessible.
2642
2643config MITIGATION_SPECTRE_V1
2644	bool "Mitigate SPECTRE V1 hardware bug"
2645	default y
2646	help
2647	  Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
2648	  class of side channel attacks that takes advantage of speculative
2649	  execution that bypasses conditional branch instructions used for
2650	  memory access bounds check.
2651	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2652
2653config MITIGATION_SPECTRE_V2
2654	bool "Mitigate SPECTRE V2 hardware bug"
2655	default y
2656	help
2657	  Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
2658	  V2 is a class of side channel attacks that takes advantage of
2659	  indirect branch predictors inside the processor. In Spectre variant 2
2660	  attacks, the attacker can steer speculative indirect branches in the
2661	  victim to gadget code by poisoning the branch target buffer of a CPU
2662	  used for predicting indirect branch addresses.
2663	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2664
2665config MITIGATION_SRBDS
2666	bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
2667	depends on CPU_SUP_INTEL
2668	default y
2669	help
2670	  Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
2671	  SRBDS is a hardware vulnerability that allows Microarchitectural Data
2672	  Sampling (MDS) techniques to infer values returned from special
2673	  register accesses. An unprivileged user can extract values returned
2674	  from RDRAND and RDSEED executed on another core or sibling thread
2675	  using MDS techniques.
2676	  See also
2677	  <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
2678
2679config MITIGATION_SSB
2680	bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
2681	default y
2682	help
2683	  Enable mitigation for Speculative Store Bypass (SSB). SSB is a
2684	  hardware security vulnerability and its exploitation takes advantage
2685	  of speculative execution in a similar way to the Meltdown and Spectre
2686	  security vulnerabilities.
2687
2688config MITIGATION_ITS
2689	bool "Enable Indirect Target Selection mitigation"
2690	depends on CPU_SUP_INTEL && X86_64
2691	depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK
2692	select EXECMEM
2693	default y
2694	help
2695	  Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in
2696	  BPU on some Intel CPUs that may allow Spectre V2 style attacks. If
2697	  disabled, mitigation cannot be enabled via cmdline.
2698	  See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst>
2699
2700endif
2701
2702config ARCH_HAS_ADD_PAGES
2703	def_bool y
2704	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2705
2706menu "Power management and ACPI options"
2707
2708config ARCH_HIBERNATION_HEADER
2709	def_bool y
2710	depends on HIBERNATION
2711
2712source "kernel/power/Kconfig"
2713
2714source "drivers/acpi/Kconfig"
2715
2716config X86_APM_BOOT
2717	def_bool y
2718	depends on APM
2719
2720menuconfig APM
2721	tristate "APM (Advanced Power Management) BIOS support"
2722	depends on X86_32 && PM_SLEEP
2723	help
2724	  APM is a BIOS specification for saving power using several different
2725	  techniques. This is mostly useful for battery powered laptops with
2726	  APM compliant BIOSes. If you say Y here, the system time will be
2727	  reset after a RESUME operation, the /proc/apm device will provide
2728	  battery status information, and user-space programs will receive
2729	  notification of APM "events" (e.g. battery status change).
2730
2731	  If you select "Y" here, you can disable actual use of the APM
2732	  BIOS by passing the "apm=off" option to the kernel at boot time.
2733
2734	  Note that the APM support is almost completely disabled for
2735	  machines with more than one CPU.
2736
2737	  In order to use APM, you will need supporting software. For location
2738	  and more information, read <file:Documentation/power/apm-acpi.rst>
2739	  and the Battery Powered Linux mini-HOWTO, available from
2740	  <http://www.tldp.org/docs.html#howto>.
2741
2742	  This driver does not spin down disk drives (see the hdparm(8)
2743	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2744	  VESA-compliant "green" monitors.
2745
2746	  This driver does not support the TI 4000M TravelMate and the ACER
2747	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2748	  desktop machines also don't have compliant BIOSes, and this driver
2749	  may cause those machines to panic during the boot phase.
2750
2751	  Generally, if you don't have a battery in your machine, there isn't
2752	  much point in using this driver and you should say N. If you get
2753	  random kernel OOPSes or reboots that don't seem to be related to
2754	  anything, try disabling/enabling this option (or disabling/enabling
2755	  APM in your BIOS).
2756
2757	  Some other things you should try when experiencing seemingly random,
2758	  "weird" problems:
2759
2760	  1) make sure that you have enough swap space and that it is
2761	  enabled.
2762	  2) pass the "idle=poll" option to the kernel
2763	  3) switch on floating point emulation in the kernel and pass
2764	  the "no387" option to the kernel
2765	  4) pass the "floppy=nodma" option to the kernel
2766	  5) pass the "mem=4M" option to the kernel (thereby disabling
2767	  all but the first 4 MB of RAM)
2768	  6) make sure that the CPU is not over clocked.
2769	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2770	  8) disable the cache from your BIOS settings
2771	  9) install a fan for the video card or exchange video RAM
2772	  10) install a better fan for the CPU
2773	  11) exchange RAM chips
2774	  12) exchange the motherboard.
2775
2776	  To compile this driver as a module, choose M here: the
2777	  module will be called apm.
2778
2779if APM
2780
2781config APM_IGNORE_USER_SUSPEND
2782	bool "Ignore USER SUSPEND"
2783	help
2784	  This option will ignore USER SUSPEND requests. On machines with a
2785	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2786	  series notebooks, it is necessary to say Y because of a BIOS bug.
2787
2788config APM_DO_ENABLE
2789	bool "Enable PM at boot time"
2790	help
2791	  Enable APM features at boot time. From page 36 of the APM BIOS
2792	  specification: "When disabled, the APM BIOS does not automatically
2793	  power manage devices, enter the Standby State, enter the Suspend
2794	  State, or take power saving steps in response to CPU Idle calls."
2795	  This driver will make CPU Idle calls when Linux is idle (unless this
2796	  feature is turned off -- see "Do CPU IDLE calls", below). This
2797	  should always save battery power, but more complicated APM features
2798	  will be dependent on your BIOS implementation. You may need to turn
2799	  this option off if your computer hangs at boot time when using APM
2800	  support, or if it beeps continuously instead of suspending. Turn
2801	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2802	  T400CDT. This is off by default since most machines do fine without
2803	  this feature.
2804
2805config APM_CPU_IDLE
2806	depends on CPU_IDLE
2807	bool "Make CPU Idle calls when idle"
2808	help
2809	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2810	  On some machines, this can activate improved power savings, such as
2811	  a slowed CPU clock rate, when the machine is idle. These idle calls
2812	  are made after the idle loop has run for some length of time (e.g.,
2813	  333 mS). On some machines, this will cause a hang at boot time or
2814	  whenever the CPU becomes idle. (On machines with more than one CPU,
2815	  this option does nothing.)
2816
2817config APM_DISPLAY_BLANK
2818	bool "Enable console blanking using APM"
2819	help
2820	  Enable console blanking using the APM. Some laptops can use this to
2821	  turn off the LCD backlight when the screen blanker of the Linux
2822	  virtual console blanks the screen. Note that this is only used by
2823	  the virtual console screen blanker, and won't turn off the backlight
2824	  when using the X Window system. This also doesn't have anything to
2825	  do with your VESA-compliant power-saving monitor. Further, this
2826	  option doesn't work for all laptops -- it might not turn off your
2827	  backlight at all, or it might print a lot of errors to the console,
2828	  especially if you are using gpm.
2829
2830config APM_ALLOW_INTS
2831	bool "Allow interrupts during APM BIOS calls"
2832	help
2833	  Normally we disable external interrupts while we are making calls to
2834	  the APM BIOS as a measure to lessen the effects of a badly behaving
2835	  BIOS implementation.  The BIOS should reenable interrupts if it
2836	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2837	  many of the newer IBM Thinkpads.  If you experience hangs when you
2838	  suspend, try setting this to Y.  Otherwise, say N.
2839
2840endif # APM
2841
2842source "drivers/cpufreq/Kconfig"
2843
2844source "drivers/cpuidle/Kconfig"
2845
2846source "drivers/idle/Kconfig"
2847
2848endmenu
2849
2850menu "Bus options (PCI etc.)"
2851
2852choice
2853	prompt "PCI access mode"
2854	depends on X86_32 && PCI
2855	default PCI_GOANY
2856	help
2857	  On PCI systems, the BIOS can be used to detect the PCI devices and
2858	  determine their configuration. However, some old PCI motherboards
2859	  have BIOS bugs and may crash if this is done. Also, some embedded
2860	  PCI-based systems don't have any BIOS at all. Linux can also try to
2861	  detect the PCI hardware directly without using the BIOS.
2862
2863	  With this option, you can specify how Linux should detect the
2864	  PCI devices. If you choose "BIOS", the BIOS will be used,
2865	  if you choose "Direct", the BIOS won't be used, and if you
2866	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2867	  If you choose "Any", the kernel will try MMCONFIG, then the
2868	  direct access method and falls back to the BIOS if that doesn't
2869	  work. If unsure, go with the default, which is "Any".
2870
2871config PCI_GOBIOS
2872	bool "BIOS"
2873
2874config PCI_GOMMCONFIG
2875	bool "MMConfig"
2876
2877config PCI_GODIRECT
2878	bool "Direct"
2879
2880config PCI_GOOLPC
2881	bool "OLPC XO-1"
2882	depends on OLPC
2883
2884config PCI_GOANY
2885	bool "Any"
2886
2887endchoice
2888
2889config PCI_BIOS
2890	def_bool y
2891	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2892
2893# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2894config PCI_DIRECT
2895	def_bool y
2896	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2897
2898config PCI_MMCONFIG
2899	bool "Support mmconfig PCI config space access" if X86_64
2900	default y
2901	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2902	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2903	help
2904	  Add support for accessing the PCI configuration space as a memory
2905	  mapped area. It is the recommended method if the system supports
2906	  this (it must have PCI Express and ACPI for it to be available).
2907
2908	  In the unlikely case that enabling this configuration option causes
2909	  problems, the mechanism can be switched off with the 'pci=nommconf'
2910	  command line parameter.
2911
2912	  Say N only if you are sure that your platform does not support this
2913	  access method or you have problems caused by it.
2914
2915	  Say Y otherwise.
2916
2917config PCI_OLPC
2918	def_bool y
2919	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2920
2921config PCI_XEN
2922	def_bool y
2923	depends on PCI && XEN
2924
2925config MMCONF_FAM10H
2926	def_bool y
2927	depends on X86_64 && PCI_MMCONFIG && ACPI
2928
2929config PCI_CNB20LE_QUIRK
2930	bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT
2931	depends on X86_32 && PCI
2932	help
2933	  Read the PCI windows out of the CNB20LE host bridge. This allows
2934	  PCI hotplug to work on systems with the CNB20LE chipset which do
2935	  not have ACPI.
2936
2937	  The ServerWorks (later Broadcom) CNB20LE was a chipset designed
2938	  most probably only for Pentium III.
2939
2940	  To find out if you have such a chipset, search for a PCI device with
2941	  1166:0009 PCI IDs, for example by executing
2942		lspci -nn | grep '1166:0009'
2943	  The code is inactive if there is none.
2944
2945	  There's no public spec for this chipset, and this functionality
2946	  is known to be incomplete.
2947
2948	  You should say N unless you know you need this.
2949
2950config ISA_BUS
2951	bool "ISA bus support on modern systems" if EXPERT
2952	help
2953	  Expose ISA bus device drivers and options available for selection and
2954	  configuration. Enable this option if your target machine has an ISA
2955	  bus. ISA is an older system, displaced by PCI and newer bus
2956	  architectures -- if your target machine is modern, it probably does
2957	  not have an ISA bus.
2958
2959	  If unsure, say N.
2960
2961# x86_64 have no ISA slots, but can have ISA-style DMA.
2962config ISA_DMA_API
2963	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2964	default y
2965	help
2966	  Enables ISA-style DMA support for devices requiring such controllers.
2967	  If unsure, say Y.
2968
2969if X86_32
2970
2971config ISA
2972	bool "ISA support"
2973	help
2974	  Find out whether you have ISA slots on your motherboard.  ISA is the
2975	  name of a bus system, i.e. the way the CPU talks to the other stuff
2976	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2977	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2978	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2979
2980config SCx200
2981	tristate "NatSemi SCx200 support"
2982	help
2983	  This provides basic support for National Semiconductor's
2984	  (now AMD's) Geode processors.  The driver probes for the
2985	  PCI-IDs of several on-chip devices, so its a good dependency
2986	  for other scx200_* drivers.
2987
2988	  If compiled as a module, the driver is named scx200.
2989
2990config SCx200HR_TIMER
2991	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2992	depends on SCx200
2993	default y
2994	help
2995	  This driver provides a clocksource built upon the on-chip
2996	  27MHz high-resolution timer.  Its also a workaround for
2997	  NSC Geode SC-1100's buggy TSC, which loses time when the
2998	  processor goes idle (as is done by the scheduler).  The
2999	  other workaround is idle=poll boot option.
3000
3001config OLPC
3002	bool "One Laptop Per Child support"
3003	depends on !X86_PAE
3004	select GPIOLIB
3005	select OF
3006	select OF_PROMTREE
3007	select IRQ_DOMAIN
3008	select OLPC_EC
3009	help
3010	  Add support for detecting the unique features of the OLPC
3011	  XO hardware.
3012
3013config OLPC_XO1_PM
3014	bool "OLPC XO-1 Power Management"
3015	depends on OLPC && MFD_CS5535=y && PM_SLEEP
3016	help
3017	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
3018
3019config OLPC_XO1_RTC
3020	bool "OLPC XO-1 Real Time Clock"
3021	depends on OLPC_XO1_PM && RTC_DRV_CMOS
3022	help
3023	  Add support for the XO-1 real time clock, which can be used as a
3024	  programmable wakeup source.
3025
3026config OLPC_XO1_SCI
3027	bool "OLPC XO-1 SCI extras"
3028	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
3029	depends on INPUT=y
3030	select POWER_SUPPLY
3031	help
3032	  Add support for SCI-based features of the OLPC XO-1 laptop:
3033	   - EC-driven system wakeups
3034	   - Power button
3035	   - Ebook switch
3036	   - Lid switch
3037	   - AC adapter status updates
3038	   - Battery status updates
3039
3040config OLPC_XO15_SCI
3041	bool "OLPC XO-1.5 SCI extras"
3042	depends on OLPC && ACPI
3043	select POWER_SUPPLY
3044	help
3045	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
3046	   - EC-driven system wakeups
3047	   - AC adapter status updates
3048	   - Battery status updates
3049
3050config GEODE_COMMON
3051	bool
3052
3053config ALIX
3054	bool "PCEngines ALIX System Support (LED setup)"
3055	select GPIOLIB
3056	select GEODE_COMMON
3057	help
3058	  This option enables system support for the PCEngines ALIX.
3059	  At present this just sets up LEDs for GPIO control on
3060	  ALIX2/3/6 boards.  However, other system specific setup should
3061	  get added here.
3062
3063	  Note: You must still enable the drivers for GPIO and LED support
3064	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
3065
3066	  Note: You have to set alix.force=1 for boards with Award BIOS.
3067
3068config NET5501
3069	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
3070	select GPIOLIB
3071	select GEODE_COMMON
3072	help
3073	  This option enables system support for the Soekris Engineering net5501.
3074
3075config GEOS
3076	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
3077	select GPIOLIB
3078	select GEODE_COMMON
3079	depends on DMI
3080	help
3081	  This option enables system support for the Traverse Technologies GEOS.
3082
3083config TS5500
3084	bool "Technologic Systems TS-5500 platform support"
3085	depends on MELAN
3086	select CHECK_SIGNATURE
3087	select NEW_LEDS
3088	select LEDS_CLASS
3089	help
3090	  This option enables system support for the Technologic Systems TS-5500.
3091
3092endif # X86_32
3093
3094config AMD_NB
3095	def_bool y
3096	depends on AMD_NODE
3097
3098config AMD_NODE
3099	def_bool y
3100	depends on CPU_SUP_AMD && PCI
3101
3102endmenu
3103
3104menu "Binary Emulations"
3105
3106config IA32_EMULATION
3107	bool "IA32 Emulation"
3108	depends on X86_64
3109	select ARCH_WANT_OLD_COMPAT_IPC
3110	select BINFMT_ELF
3111	select COMPAT_OLD_SIGACTION
3112	help
3113	  Include code to run legacy 32-bit programs under a
3114	  64-bit kernel. You should likely turn this on, unless you're
3115	  100% sure that you don't have any 32-bit programs left.
3116
3117config IA32_EMULATION_DEFAULT_DISABLED
3118	bool "IA32 emulation disabled by default"
3119	default n
3120	depends on IA32_EMULATION
3121	help
3122	  Make IA32 emulation disabled by default. This prevents loading 32-bit
3123	  processes and access to 32-bit syscalls. If unsure, leave it to its
3124	  default value.
3125
3126config X86_X32_ABI
3127	bool "x32 ABI for 64-bit mode"
3128	depends on X86_64
3129	# llvm-objcopy does not convert x86_64 .note.gnu.property or
3130	# compressed debug sections to x86_x32 properly:
3131	# https://github.com/ClangBuiltLinux/linux/issues/514
3132	# https://github.com/ClangBuiltLinux/linux/issues/1141
3133	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3134	help
3135	  Include code to run binaries for the x32 native 32-bit ABI
3136	  for 64-bit processors.  An x32 process gets access to the
3137	  full 64-bit register file and wide data path while leaving
3138	  pointers at 32 bits for smaller memory footprint.
3139
3140config COMPAT_32
3141	def_bool y
3142	depends on IA32_EMULATION || X86_32
3143	select HAVE_UID16
3144	select OLD_SIGSUSPEND3
3145
3146config COMPAT
3147	def_bool y
3148	depends on IA32_EMULATION || X86_X32_ABI
3149
3150config COMPAT_FOR_U64_ALIGNMENT
3151	def_bool y
3152	depends on COMPAT
3153
3154endmenu
3155
3156config HAVE_ATOMIC_IOMAP
3157	def_bool y
3158	depends on X86_32
3159
3160source "arch/x86/kvm/Kconfig"
3161
3162source "arch/x86/Kconfig.cpufeatures"
3163
3164source "arch/x86/Kconfig.assembler"
3165