xref: /linux/arch/x86/Kconfig (revision 13b25489b6f8bd73ed65f07928f7c27a481f1820)
1# SPDX-License-Identifier: GPL-2.0
2# Select 32 or 64 bit
3config 64BIT
4	bool "64-bit kernel" if "$(ARCH)" = "x86"
5	default "$(ARCH)" != "i386"
6	help
7	  Say yes to build a 64-bit kernel - formerly known as x86_64
8	  Say no to build a 32-bit kernel - formerly known as i386
9
10config X86_32
11	def_bool y
12	depends on !64BIT
13	# Options that are inherently 32-bit kernel only:
14	select ARCH_WANT_IPC_PARSE_VERSION
15	select CLKSRC_I8253
16	select CLONE_BACKWARDS
17	select GENERIC_VDSO_32
18	select HAVE_DEBUG_STACKOVERFLOW
19	select KMAP_LOCAL
20	select MODULES_USE_ELF_REL
21	select OLD_SIGACTION
22	select ARCH_SPLIT_ARG64
23
24config X86_64
25	def_bool y
26	depends on 64BIT
27	# Options that are inherently 64-bit kernel only:
28	select ARCH_HAS_GIGANTIC_PAGE
29	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30	select ARCH_SUPPORTS_PER_VMA_LOCK
31	select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
32	select HAVE_ARCH_SOFT_DIRTY
33	select MODULES_USE_ELF_RELA
34	select NEED_DMA_MAP_STATE
35	select SWIOTLB
36	select ARCH_HAS_ELFCORE_COMPAT
37	select ZONE_DMA32
38	select EXECMEM if DYNAMIC_FTRACE
39
40config FORCE_DYNAMIC_FTRACE
41	def_bool y
42	depends on X86_32
43	depends on FUNCTION_TRACER
44	select DYNAMIC_FTRACE
45	help
46	  We keep the static function tracing (!DYNAMIC_FTRACE) around
47	  in order to test the non static function tracing in the
48	  generic code, as other architectures still use it. But we
49	  only need to keep it around for x86_64. No need to keep it
50	  for x86_32. For x86_32, force DYNAMIC_FTRACE.
51#
52# Arch settings
53#
54# ( Note that options that are marked 'if X86_64' could in principle be
55#   ported to 32-bit as well. )
56#
57config X86
58	def_bool y
59	#
60	# Note: keep this list sorted alphabetically
61	#
62	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
63	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
64	select ACPI_HOTPLUG_CPU			if ACPI_PROCESSOR && HOTPLUG_CPU
65	select ARCH_32BIT_OFF_T			if X86_32
66	select ARCH_CLOCKSOURCE_INIT
67	select ARCH_CONFIGURES_CPU_MITIGATIONS
68	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
69	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
70	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
71	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
72	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
73	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
74	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
75	select ARCH_HAS_CACHE_LINE_SIZE
76	select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
77	select ARCH_HAS_CPU_FINALIZE_INIT
78	select ARCH_HAS_CPU_PASID		if IOMMU_SVA
79	select ARCH_HAS_CURRENT_STACK_POINTER
80	select ARCH_HAS_DEBUG_VIRTUAL
81	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
82	select ARCH_HAS_DEVMEM_IS_ALLOWED
83	select ARCH_HAS_DMA_OPS			if GART_IOMMU || XEN
84	select ARCH_HAS_EARLY_DEBUG		if KGDB
85	select ARCH_HAS_ELF_RANDOMIZE
86	select ARCH_HAS_FAST_MULTIPLIER
87	select ARCH_HAS_FORTIFY_SOURCE
88	select ARCH_HAS_GCOV_PROFILE_ALL
89	select ARCH_HAS_KCOV			if X86_64
90	select ARCH_HAS_KERNEL_FPU_SUPPORT
91	select ARCH_HAS_MEM_ENCRYPT
92	select ARCH_HAS_MEMBARRIER_SYNC_CORE
93	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
94	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
95	select ARCH_HAS_PMEM_API		if X86_64
96	select ARCH_HAS_PTE_DEVMAP		if X86_64
97	select ARCH_HAS_PTE_SPECIAL
98	select ARCH_HAS_HW_PTE_YOUNG
99	select ARCH_HAS_NONLEAF_PMD_YOUNG	if PGTABLE_LEVELS > 2
100	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
101	select ARCH_HAS_COPY_MC			if X86_64
102	select ARCH_HAS_SET_MEMORY
103	select ARCH_HAS_SET_DIRECT_MAP
104	select ARCH_HAS_STRICT_KERNEL_RWX
105	select ARCH_HAS_STRICT_MODULE_RWX
106	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
107	select ARCH_HAS_SYSCALL_WRAPPER
108	select ARCH_HAS_UBSAN
109	select ARCH_HAS_DEBUG_WX
110	select ARCH_HAS_ZONE_DMA_SET if EXPERT
111	select ARCH_HAVE_NMI_SAFE_CMPXCHG
112	select ARCH_HAVE_EXTRA_ELF_NOTES
113	select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
114	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
115	select ARCH_MIGHT_HAVE_PC_PARPORT
116	select ARCH_MIGHT_HAVE_PC_SERIO
117	select ARCH_STACKWALK
118	select ARCH_SUPPORTS_ACPI
119	select ARCH_SUPPORTS_ATOMIC_RMW
120	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
121	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
122	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
123	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
124	select ARCH_SUPPORTS_CFI_CLANG		if X86_64
125	select ARCH_USES_CFI_TRAPS		if X86_64 && CFI_CLANG
126	select ARCH_SUPPORTS_LTO_CLANG
127	select ARCH_SUPPORTS_LTO_CLANG_THIN
128	select ARCH_SUPPORTS_RT
129	select ARCH_SUPPORTS_AUTOFDO_CLANG
130	select ARCH_SUPPORTS_PROPELLER_CLANG    if X86_64
131	select ARCH_USE_BUILTIN_BSWAP
132	select ARCH_USE_CMPXCHG_LOCKREF		if X86_CMPXCHG64
133	select ARCH_USE_MEMTEST
134	select ARCH_USE_QUEUED_RWLOCKS
135	select ARCH_USE_QUEUED_SPINLOCKS
136	select ARCH_USE_SYM_ANNOTATIONS
137	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
138	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
139	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
140	select ARCH_WANTS_NO_INSTR
141	select ARCH_WANT_GENERAL_HUGETLB
142	select ARCH_WANT_HUGE_PMD_SHARE
143	select ARCH_WANT_LD_ORPHAN_WARN
144	select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP	if X86_64
145	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP	if X86_64
146	select ARCH_WANTS_THP_SWAP		if X86_64
147	select ARCH_HAS_PARANOID_L1D_FLUSH
148	select BUILDTIME_TABLE_SORT
149	select CLKEVT_I8253
150	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
151	select CLOCKSOURCE_WATCHDOG
152	# Word-size accesses may read uninitialized data past the trailing \0
153	# in strings and cause false KMSAN reports.
154	select DCACHE_WORD_ACCESS		if !KMSAN
155	select DYNAMIC_SIGFRAME
156	select EDAC_ATOMIC_SCRUB
157	select EDAC_SUPPORT
158	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
159	select GENERIC_CLOCKEVENTS_BROADCAST_IDLE	if GENERIC_CLOCKEVENTS_BROADCAST
160	select GENERIC_CLOCKEVENTS_MIN_ADJUST
161	select GENERIC_CMOS_UPDATE
162	select GENERIC_CPU_AUTOPROBE
163	select GENERIC_CPU_DEVICES
164	select GENERIC_CPU_VULNERABILITIES
165	select GENERIC_EARLY_IOREMAP
166	select GENERIC_ENTRY
167	select GENERIC_IOMAP
168	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
169	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
170	select GENERIC_IRQ_MIGRATION		if SMP
171	select GENERIC_IRQ_PROBE
172	select GENERIC_IRQ_RESERVATION_MODE
173	select GENERIC_IRQ_SHOW
174	select GENERIC_PENDING_IRQ		if SMP
175	select GENERIC_PTDUMP
176	select GENERIC_SMP_IDLE_THREAD
177	select GENERIC_TIME_VSYSCALL
178	select GENERIC_GETTIMEOFDAY
179	select GENERIC_VDSO_TIME_NS
180	select GENERIC_VDSO_OVERFLOW_PROTECT
181	select GUP_GET_PXX_LOW_HIGH		if X86_PAE
182	select HARDIRQS_SW_RESEND
183	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
184	select HAS_IOPORT
185	select HAVE_ACPI_APEI			if ACPI
186	select HAVE_ACPI_APEI_NMI		if ACPI
187	select HAVE_ALIGNED_STRUCT_PAGE
188	select HAVE_ARCH_AUDITSYSCALL
189	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
190	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
191	select HAVE_ARCH_JUMP_LABEL
192	select HAVE_ARCH_JUMP_LABEL_RELATIVE
193	select HAVE_ARCH_KASAN			if X86_64
194	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
195	select HAVE_ARCH_KFENCE
196	select HAVE_ARCH_KMSAN			if X86_64
197	select HAVE_ARCH_KGDB
198	select HAVE_ARCH_MMAP_RND_BITS		if MMU
199	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
200	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
201	select HAVE_ARCH_PREL32_RELOCATIONS
202	select HAVE_ARCH_SECCOMP_FILTER
203	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
204	select HAVE_ARCH_STACKLEAK
205	select HAVE_ARCH_TRACEHOOK
206	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
207	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
208	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
209	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
210	select HAVE_ARCH_VMAP_STACK		if X86_64
211	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
212	select HAVE_ARCH_WITHIN_STACK_FRAMES
213	select HAVE_ASM_MODVERSIONS
214	select HAVE_CMPXCHG_DOUBLE
215	select HAVE_CMPXCHG_LOCAL
216	select HAVE_CONTEXT_TRACKING_USER		if X86_64
217	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
218	select HAVE_C_RECORDMCOUNT
219	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
220	select HAVE_OBJTOOL_NOP_MCOUNT		if HAVE_OBJTOOL_MCOUNT
221	select HAVE_BUILDTIME_MCOUNT_SORT
222	select HAVE_DEBUG_KMEMLEAK
223	select HAVE_DMA_CONTIGUOUS
224	select HAVE_DYNAMIC_FTRACE
225	select HAVE_DYNAMIC_FTRACE_WITH_REGS
226	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
227	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
228	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
229	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
230	select HAVE_EBPF_JIT
231	select HAVE_EFFICIENT_UNALIGNED_ACCESS
232	select HAVE_EISA
233	select HAVE_EXIT_THREAD
234	select HAVE_GUP_FAST
235	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
236	select HAVE_FTRACE_MCOUNT_RECORD
237	select HAVE_FUNCTION_GRAPH_RETVAL	if HAVE_FUNCTION_GRAPH_TRACER
238	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
239	select HAVE_FUNCTION_TRACER
240	select HAVE_GCC_PLUGINS
241	select HAVE_HW_BREAKPOINT
242	select HAVE_IOREMAP_PROT
243	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
244	select HAVE_IRQ_TIME_ACCOUNTING
245	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
246	select HAVE_KERNEL_BZIP2
247	select HAVE_KERNEL_GZIP
248	select HAVE_KERNEL_LZ4
249	select HAVE_KERNEL_LZMA
250	select HAVE_KERNEL_LZO
251	select HAVE_KERNEL_XZ
252	select HAVE_KERNEL_ZSTD
253	select HAVE_KPROBES
254	select HAVE_KPROBES_ON_FTRACE
255	select HAVE_FUNCTION_ERROR_INJECTION
256	select HAVE_KRETPROBES
257	select HAVE_RETHOOK
258	select HAVE_LIVEPATCH			if X86_64
259	select HAVE_MIXED_BREAKPOINTS_REGS
260	select HAVE_MOD_ARCH_SPECIFIC
261	select HAVE_MOVE_PMD
262	select HAVE_MOVE_PUD
263	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
264	select HAVE_NMI
265	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
266	select HAVE_OBJTOOL			if X86_64
267	select HAVE_OPTPROBES
268	select HAVE_PAGE_SIZE_4KB
269	select HAVE_PCSPKR_PLATFORM
270	select HAVE_PERF_EVENTS
271	select HAVE_PERF_EVENTS_NMI
272	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
273	select HAVE_PCI
274	select HAVE_PERF_REGS
275	select HAVE_PERF_USER_STACK_DUMP
276	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
277	select MMU_GATHER_MERGE_VMAS
278	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
279	select HAVE_REGS_AND_STACK_ACCESS_API
280	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
281	select HAVE_FUNCTION_ARG_ACCESS_API
282	select HAVE_SETUP_PER_CPU_AREA
283	select HAVE_SOFTIRQ_ON_OWN_STACK
284	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
285	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
286	select HAVE_STATIC_CALL
287	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
288	select HAVE_PREEMPT_DYNAMIC_CALL
289	select HAVE_RSEQ
290	select HAVE_RUST			if X86_64
291	select HAVE_SYSCALL_TRACEPOINTS
292	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
293	select HAVE_UNSTABLE_SCHED_CLOCK
294	select HAVE_USER_RETURN_NOTIFIER
295	select HAVE_GENERIC_VDSO
296	select VDSO_GETRANDOM			if X86_64
297	select HOTPLUG_PARALLEL			if SMP && X86_64
298	select HOTPLUG_SMT			if SMP
299	select HOTPLUG_SPLIT_STARTUP		if SMP && X86_32
300	select IRQ_FORCED_THREADING
301	select LOCK_MM_AND_FIND_VMA
302	select NEED_PER_CPU_EMBED_FIRST_CHUNK
303	select NEED_PER_CPU_PAGE_FIRST_CHUNK
304	select NEED_SG_DMA_LENGTH
305	select NUMA_MEMBLKS			if NUMA
306	select PCI_DOMAINS			if PCI
307	select PCI_LOCKLESS_CONFIG		if PCI
308	select PERF_EVENTS
309	select RTC_LIB
310	select RTC_MC146818_LIB
311	select SPARSE_IRQ
312	select SYSCTL_EXCEPTION_TRACE
313	select THREAD_INFO_IN_TASK
314	select TRACE_IRQFLAGS_SUPPORT
315	select TRACE_IRQFLAGS_NMI_SUPPORT
316	select USER_STACKTRACE_SUPPORT
317	select HAVE_ARCH_KCSAN			if X86_64
318	select PROC_PID_ARCH_STATUS		if PROC_FS
319	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
320	select FUNCTION_ALIGNMENT_16B		if X86_64 || X86_ALIGNMENT_16
321	select FUNCTION_ALIGNMENT_4B
322	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
323	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
324
325config INSTRUCTION_DECODER
326	def_bool y
327	depends on KPROBES || PERF_EVENTS || UPROBES
328
329config OUTPUT_FORMAT
330	string
331	default "elf32-i386" if X86_32
332	default "elf64-x86-64" if X86_64
333
334config LOCKDEP_SUPPORT
335	def_bool y
336
337config STACKTRACE_SUPPORT
338	def_bool y
339
340config MMU
341	def_bool y
342
343config ARCH_MMAP_RND_BITS_MIN
344	default 28 if 64BIT
345	default 8
346
347config ARCH_MMAP_RND_BITS_MAX
348	default 32 if 64BIT
349	default 16
350
351config ARCH_MMAP_RND_COMPAT_BITS_MIN
352	default 8
353
354config ARCH_MMAP_RND_COMPAT_BITS_MAX
355	default 16
356
357config SBUS
358	bool
359
360config GENERIC_ISA_DMA
361	def_bool y
362	depends on ISA_DMA_API
363
364config GENERIC_CSUM
365	bool
366	default y if KMSAN || KASAN
367
368config GENERIC_BUG
369	def_bool y
370	depends on BUG
371	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
372
373config GENERIC_BUG_RELATIVE_POINTERS
374	bool
375
376config ARCH_MAY_HAVE_PC_FDC
377	def_bool y
378	depends on ISA_DMA_API
379
380config GENERIC_CALIBRATE_DELAY
381	def_bool y
382
383config ARCH_HAS_CPU_RELAX
384	def_bool y
385
386config ARCH_HIBERNATION_POSSIBLE
387	def_bool y
388
389config ARCH_SUSPEND_POSSIBLE
390	def_bool y
391
392config AUDIT_ARCH
393	def_bool y if X86_64
394
395config KASAN_SHADOW_OFFSET
396	hex
397	depends on KASAN
398	default 0xdffffc0000000000
399
400config HAVE_INTEL_TXT
401	def_bool y
402	depends on INTEL_IOMMU && ACPI
403
404config X86_64_SMP
405	def_bool y
406	depends on X86_64 && SMP
407
408config ARCH_SUPPORTS_UPROBES
409	def_bool y
410
411config FIX_EARLYCON_MEM
412	def_bool y
413
414config DYNAMIC_PHYSICAL_MASK
415	bool
416
417config PGTABLE_LEVELS
418	int
419	default 5 if X86_5LEVEL
420	default 4 if X86_64
421	default 3 if X86_PAE
422	default 2
423
424config CC_HAS_SANE_STACKPROTECTOR
425	bool
426	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
427	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
428	help
429	  We have to make sure stack protector is unconditionally disabled if
430	  the compiler produces broken code or if it does not let us control
431	  the segment on 32-bit kernels.
432
433menu "Processor type and features"
434
435config SMP
436	bool "Symmetric multi-processing support"
437	help
438	  This enables support for systems with more than one CPU. If you have
439	  a system with only one CPU, say N. If you have a system with more
440	  than one CPU, say Y.
441
442	  If you say N here, the kernel will run on uni- and multiprocessor
443	  machines, but will use only one CPU of a multiprocessor machine. If
444	  you say Y here, the kernel will run on many, but not all,
445	  uniprocessor machines. On a uniprocessor machine, the kernel
446	  will run faster if you say N here.
447
448	  Note that if you say Y here and choose architecture "586" or
449	  "Pentium" under "Processor family", the kernel will not work on 486
450	  architectures. Similarly, multiprocessor kernels for the "PPro"
451	  architecture may not work on all Pentium based boards.
452
453	  People using multiprocessor machines who say Y here should also say
454	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
455	  Management" code will be disabled if you say Y here.
456
457	  See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
458	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
459	  <http://www.tldp.org/docs.html#howto>.
460
461	  If you don't know what to do here, say N.
462
463config X86_X2APIC
464	bool "Support x2apic"
465	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
466	help
467	  This enables x2apic support on CPUs that have this feature.
468
469	  This allows 32-bit apic IDs (so it can support very large systems),
470	  and accesses the local apic via MSRs not via mmio.
471
472	  Some Intel systems circa 2022 and later are locked into x2APIC mode
473	  and can not fall back to the legacy APIC modes if SGX or TDX are
474	  enabled in the BIOS. They will boot with very reduced functionality
475	  without enabling this option.
476
477	  If you don't know what to do here, say N.
478
479config X86_POSTED_MSI
480	bool "Enable MSI and MSI-x delivery by posted interrupts"
481	depends on X86_64 && IRQ_REMAP
482	help
483	  This enables MSIs that are under interrupt remapping to be delivered as
484	  posted interrupts to the host kernel. Interrupt throughput can
485	  potentially be improved by coalescing CPU notifications during high
486	  frequency bursts.
487
488	  If you don't know what to do here, say N.
489
490config X86_MPPARSE
491	bool "Enable MPS table" if ACPI
492	default y
493	depends on X86_LOCAL_APIC
494	help
495	  For old smp systems that do not have proper acpi support. Newer systems
496	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
497
498config X86_CPU_RESCTRL
499	bool "x86 CPU resource control support"
500	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
501	select KERNFS
502	select PROC_CPU_RESCTRL		if PROC_FS
503	help
504	  Enable x86 CPU resource control support.
505
506	  Provide support for the allocation and monitoring of system resources
507	  usage by the CPU.
508
509	  Intel calls this Intel Resource Director Technology
510	  (Intel(R) RDT). More information about RDT can be found in the
511	  Intel x86 Architecture Software Developer Manual.
512
513	  AMD calls this AMD Platform Quality of Service (AMD QoS).
514	  More information about AMD QoS can be found in the AMD64 Technology
515	  Platform Quality of Service Extensions manual.
516
517	  Say N if unsure.
518
519config X86_FRED
520	bool "Flexible Return and Event Delivery"
521	depends on X86_64
522	help
523	  When enabled, try to use Flexible Return and Event Delivery
524	  instead of the legacy SYSCALL/SYSENTER/IDT architecture for
525	  ring transitions and exception/interrupt handling if the
526	  system supports it.
527
528config X86_BIGSMP
529	bool "Support for big SMP systems with more than 8 CPUs"
530	depends on SMP && X86_32
531	help
532	  This option is needed for the systems that have more than 8 CPUs.
533
534config X86_EXTENDED_PLATFORM
535	bool "Support for extended (non-PC) x86 platforms"
536	default y
537	help
538	  If you disable this option then the kernel will only support
539	  standard PC platforms. (which covers the vast majority of
540	  systems out there.)
541
542	  If you enable this option then you'll be able to select support
543	  for the following non-PC x86 platforms, depending on the value of
544	  CONFIG_64BIT.
545
546	  32-bit platforms (CONFIG_64BIT=n):
547		Goldfish (Android emulator)
548		AMD Elan
549		RDC R-321x SoC
550		SGI 320/540 (Visual Workstation)
551		STA2X11-based (e.g. Northville)
552		Moorestown MID devices
553
554	  64-bit platforms (CONFIG_64BIT=y):
555		Numascale NumaChip
556		ScaleMP vSMP
557		SGI Ultraviolet
558
559	  If you have one of these systems, or if you want to build a
560	  generic distribution kernel, say Y here - otherwise say N.
561
562# This is an alphabetically sorted list of 64 bit extended platforms
563# Please maintain the alphabetic order if and when there are additions
564config X86_NUMACHIP
565	bool "Numascale NumaChip"
566	depends on X86_64
567	depends on X86_EXTENDED_PLATFORM
568	depends on NUMA
569	depends on SMP
570	depends on X86_X2APIC
571	depends on PCI_MMCONFIG
572	help
573	  Adds support for Numascale NumaChip large-SMP systems. Needed to
574	  enable more than ~168 cores.
575	  If you don't have one of these, you should say N here.
576
577config X86_VSMP
578	bool "ScaleMP vSMP"
579	select HYPERVISOR_GUEST
580	select PARAVIRT
581	depends on X86_64 && PCI
582	depends on X86_EXTENDED_PLATFORM
583	depends on SMP
584	help
585	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
586	  supposed to run on these EM64T-based machines.  Only choose this option
587	  if you have one of these machines.
588
589config X86_UV
590	bool "SGI Ultraviolet"
591	depends on X86_64
592	depends on X86_EXTENDED_PLATFORM
593	depends on NUMA
594	depends on EFI
595	depends on KEXEC_CORE
596	depends on X86_X2APIC
597	depends on PCI
598	help
599	  This option is needed in order to support SGI Ultraviolet systems.
600	  If you don't have one of these, you should say N here.
601
602# Following is an alphabetically sorted list of 32 bit extended platforms
603# Please maintain the alphabetic order if and when there are additions
604
605config X86_GOLDFISH
606	bool "Goldfish (Virtual Platform)"
607	depends on X86_EXTENDED_PLATFORM
608	help
609	  Enable support for the Goldfish virtual platform used primarily
610	  for Android development. Unless you are building for the Android
611	  Goldfish emulator say N here.
612
613config X86_INTEL_CE
614	bool "CE4100 TV platform"
615	depends on PCI
616	depends on PCI_GODIRECT
617	depends on X86_IO_APIC
618	depends on X86_32
619	depends on X86_EXTENDED_PLATFORM
620	select X86_REBOOTFIXUPS
621	select OF
622	select OF_EARLY_FLATTREE
623	help
624	  Select for the Intel CE media processor (CE4100) SOC.
625	  This option compiles in support for the CE4100 SOC for settop
626	  boxes and media devices.
627
628config X86_INTEL_MID
629	bool "Intel MID platform support"
630	depends on X86_EXTENDED_PLATFORM
631	depends on X86_PLATFORM_DEVICES
632	depends on PCI
633	depends on X86_64 || (PCI_GOANY && X86_32)
634	depends on X86_IO_APIC
635	select I2C
636	select DW_APB_TIMER
637	select INTEL_SCU_PCI
638	help
639	  Select to build a kernel capable of supporting Intel MID (Mobile
640	  Internet Device) platform systems which do not have the PCI legacy
641	  interfaces. If you are building for a PC class system say N here.
642
643	  Intel MID platforms are based on an Intel processor and chipset which
644	  consume less power than most of the x86 derivatives.
645
646config X86_INTEL_QUARK
647	bool "Intel Quark platform support"
648	depends on X86_32
649	depends on X86_EXTENDED_PLATFORM
650	depends on X86_PLATFORM_DEVICES
651	depends on X86_TSC
652	depends on PCI
653	depends on PCI_GOANY
654	depends on X86_IO_APIC
655	select IOSF_MBI
656	select INTEL_IMR
657	select COMMON_CLK
658	help
659	  Select to include support for Quark X1000 SoC.
660	  Say Y here if you have a Quark based system such as the Arduino
661	  compatible Intel Galileo.
662
663config X86_INTEL_LPSS
664	bool "Intel Low Power Subsystem Support"
665	depends on X86 && ACPI && PCI
666	select COMMON_CLK
667	select PINCTRL
668	select IOSF_MBI
669	help
670	  Select to build support for Intel Low Power Subsystem such as
671	  found on Intel Lynxpoint PCH. Selecting this option enables
672	  things like clock tree (common clock framework) and pincontrol
673	  which are needed by the LPSS peripheral drivers.
674
675config X86_AMD_PLATFORM_DEVICE
676	bool "AMD ACPI2Platform devices support"
677	depends on ACPI
678	select COMMON_CLK
679	select PINCTRL
680	help
681	  Select to interpret AMD specific ACPI device to platform device
682	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
683	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
684	  implemented under PINCTRL subsystem.
685
686config IOSF_MBI
687	tristate "Intel SoC IOSF Sideband support for SoC platforms"
688	depends on PCI
689	help
690	  This option enables sideband register access support for Intel SoC
691	  platforms. On these platforms the IOSF sideband is used in lieu of
692	  MSR's for some register accesses, mostly but not limited to thermal
693	  and power. Drivers may query the availability of this device to
694	  determine if they need the sideband in order to work on these
695	  platforms. The sideband is available on the following SoC products.
696	  This list is not meant to be exclusive.
697	   - BayTrail
698	   - Braswell
699	   - Quark
700
701	  You should say Y if you are running a kernel on one of these SoC's.
702
703config IOSF_MBI_DEBUG
704	bool "Enable IOSF sideband access through debugfs"
705	depends on IOSF_MBI && DEBUG_FS
706	help
707	  Select this option to expose the IOSF sideband access registers (MCR,
708	  MDR, MCRX) through debugfs to write and read register information from
709	  different units on the SoC. This is most useful for obtaining device
710	  state information for debug and analysis. As this is a general access
711	  mechanism, users of this option would have specific knowledge of the
712	  device they want to access.
713
714	  If you don't require the option or are in doubt, say N.
715
716config X86_RDC321X
717	bool "RDC R-321x SoC"
718	depends on X86_32
719	depends on X86_EXTENDED_PLATFORM
720	select M486
721	select X86_REBOOTFIXUPS
722	help
723	  This option is needed for RDC R-321x system-on-chip, also known
724	  as R-8610-(G).
725	  If you don't have one of these chips, you should say N here.
726
727config X86_32_NON_STANDARD
728	bool "Support non-standard 32-bit SMP architectures"
729	depends on X86_32 && SMP
730	depends on X86_EXTENDED_PLATFORM
731	help
732	  This option compiles in the bigsmp and STA2X11 default
733	  subarchitectures.  It is intended for a generic binary
734	  kernel. If you select them all, kernel will probe it one by
735	  one and will fallback to default.
736
737# Alphabetically sorted list of Non standard 32 bit platforms
738
739config X86_SUPPORTS_MEMORY_FAILURE
740	def_bool y
741	# MCE code calls memory_failure():
742	depends on X86_MCE
743	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
744	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
745	depends on X86_64 || !SPARSEMEM
746	select ARCH_SUPPORTS_MEMORY_FAILURE
747
748config STA2X11
749	bool "STA2X11 Companion Chip Support"
750	depends on X86_32_NON_STANDARD && PCI
751	select SWIOTLB
752	select MFD_STA2X11
753	select GPIOLIB
754	help
755	  This adds support for boards based on the STA2X11 IO-Hub,
756	  a.k.a. "ConneXt". The chip is used in place of the standard
757	  PC chipset, so all "standard" peripherals are missing. If this
758	  option is selected the kernel will still be able to boot on
759	  standard PC machines.
760
761config X86_32_IRIS
762	tristate "Eurobraille/Iris poweroff module"
763	depends on X86_32
764	help
765	  The Iris machines from EuroBraille do not have APM or ACPI support
766	  to shut themselves down properly.  A special I/O sequence is
767	  needed to do so, which is what this module does at
768	  kernel shutdown.
769
770	  This is only for Iris machines from EuroBraille.
771
772	  If unused, say N.
773
774config SCHED_OMIT_FRAME_POINTER
775	def_bool y
776	prompt "Single-depth WCHAN output"
777	depends on X86
778	help
779	  Calculate simpler /proc/<PID>/wchan values. If this option
780	  is disabled then wchan values will recurse back to the
781	  caller function. This provides more accurate wchan values,
782	  at the expense of slightly more scheduling overhead.
783
784	  If in doubt, say "Y".
785
786menuconfig HYPERVISOR_GUEST
787	bool "Linux guest support"
788	help
789	  Say Y here to enable options for running Linux under various hyper-
790	  visors. This option enables basic hypervisor detection and platform
791	  setup.
792
793	  If you say N, all options in this submenu will be skipped and
794	  disabled, and Linux guest support won't be built in.
795
796if HYPERVISOR_GUEST
797
798config PARAVIRT
799	bool "Enable paravirtualization code"
800	depends on HAVE_STATIC_CALL
801	help
802	  This changes the kernel so it can modify itself when it is run
803	  under a hypervisor, potentially improving performance significantly
804	  over full virtualization.  However, when run without a hypervisor
805	  the kernel is theoretically slower and slightly larger.
806
807config PARAVIRT_XXL
808	bool
809
810config PARAVIRT_DEBUG
811	bool "paravirt-ops debugging"
812	depends on PARAVIRT && DEBUG_KERNEL
813	help
814	  Enable to debug paravirt_ops internals.  Specifically, BUG if
815	  a paravirt_op is missing when it is called.
816
817config PARAVIRT_SPINLOCKS
818	bool "Paravirtualization layer for spinlocks"
819	depends on PARAVIRT && SMP
820	help
821	  Paravirtualized spinlocks allow a pvops backend to replace the
822	  spinlock implementation with something virtualization-friendly
823	  (for example, block the virtual CPU rather than spinning).
824
825	  It has a minimal impact on native kernels and gives a nice performance
826	  benefit on paravirtualized KVM / Xen kernels.
827
828	  If you are unsure how to answer this question, answer Y.
829
830config X86_HV_CALLBACK_VECTOR
831	def_bool n
832
833source "arch/x86/xen/Kconfig"
834
835config KVM_GUEST
836	bool "KVM Guest support (including kvmclock)"
837	depends on PARAVIRT
838	select PARAVIRT_CLOCK
839	select ARCH_CPUIDLE_HALTPOLL
840	select X86_HV_CALLBACK_VECTOR
841	default y
842	help
843	  This option enables various optimizations for running under the KVM
844	  hypervisor. It includes a paravirtualized clock, so that instead
845	  of relying on a PIT (or probably other) emulation by the
846	  underlying device model, the host provides the guest with
847	  timing infrastructure such as time of day, and system time
848
849config ARCH_CPUIDLE_HALTPOLL
850	def_bool n
851	prompt "Disable host haltpoll when loading haltpoll driver"
852	help
853	  If virtualized under KVM, disable host haltpoll.
854
855config PVH
856	bool "Support for running PVH guests"
857	help
858	  This option enables the PVH entry point for guest virtual machines
859	  as specified in the x86/HVM direct boot ABI.
860
861config PARAVIRT_TIME_ACCOUNTING
862	bool "Paravirtual steal time accounting"
863	depends on PARAVIRT
864	help
865	  Select this option to enable fine granularity task steal time
866	  accounting. Time spent executing other tasks in parallel with
867	  the current vCPU is discounted from the vCPU power. To account for
868	  that, there can be a small performance impact.
869
870	  If in doubt, say N here.
871
872config PARAVIRT_CLOCK
873	bool
874
875config JAILHOUSE_GUEST
876	bool "Jailhouse non-root cell support"
877	depends on X86_64 && PCI
878	select X86_PM_TIMER
879	help
880	  This option allows to run Linux as guest in a Jailhouse non-root
881	  cell. You can leave this option disabled if you only want to start
882	  Jailhouse and run Linux afterwards in the root cell.
883
884config ACRN_GUEST
885	bool "ACRN Guest support"
886	depends on X86_64
887	select X86_HV_CALLBACK_VECTOR
888	help
889	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
890	  a flexible, lightweight reference open-source hypervisor, built with
891	  real-time and safety-criticality in mind. It is built for embedded
892	  IOT with small footprint and real-time features. More details can be
893	  found in https://projectacrn.org/.
894
895config INTEL_TDX_GUEST
896	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
897	depends on X86_64 && CPU_SUP_INTEL
898	depends on X86_X2APIC
899	depends on EFI_STUB
900	select ARCH_HAS_CC_PLATFORM
901	select X86_MEM_ENCRYPT
902	select X86_MCE
903	select UNACCEPTED_MEMORY
904	help
905	  Support running as a guest under Intel TDX.  Without this support,
906	  the guest kernel can not boot or run under TDX.
907	  TDX includes memory encryption and integrity capabilities
908	  which protect the confidentiality and integrity of guest
909	  memory contents and CPU state. TDX guests are protected from
910	  some attacks from the VMM.
911
912endif # HYPERVISOR_GUEST
913
914source "arch/x86/Kconfig.cpu"
915
916config HPET_TIMER
917	def_bool X86_64
918	prompt "HPET Timer Support" if X86_32
919	help
920	  Use the IA-PC HPET (High Precision Event Timer) to manage
921	  time in preference to the PIT and RTC, if a HPET is
922	  present.
923	  HPET is the next generation timer replacing legacy 8254s.
924	  The HPET provides a stable time base on SMP
925	  systems, unlike the TSC, but it is more expensive to access,
926	  as it is off-chip.  The interface used is documented
927	  in the HPET spec, revision 1.
928
929	  You can safely choose Y here.  However, HPET will only be
930	  activated if the platform and the BIOS support this feature.
931	  Otherwise the 8254 will be used for timing services.
932
933	  Choose N to continue using the legacy 8254 timer.
934
935config HPET_EMULATE_RTC
936	def_bool y
937	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
938
939# Mark as expert because too many people got it wrong.
940# The code disables itself when not needed.
941config DMI
942	default y
943	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
944	bool "Enable DMI scanning" if EXPERT
945	help
946	  Enabled scanning of DMI to identify machine quirks. Say Y
947	  here unless you have verified that your setup is not
948	  affected by entries in the DMI blacklist. Required by PNP
949	  BIOS code.
950
951config GART_IOMMU
952	bool "Old AMD GART IOMMU support"
953	select IOMMU_HELPER
954	select SWIOTLB
955	depends on X86_64 && PCI && AMD_NB
956	help
957	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
958	  GART based hardware IOMMUs.
959
960	  The GART supports full DMA access for devices with 32-bit access
961	  limitations, on systems with more than 3 GB. This is usually needed
962	  for USB, sound, many IDE/SATA chipsets and some other devices.
963
964	  Newer systems typically have a modern AMD IOMMU, supported via
965	  the CONFIG_AMD_IOMMU=y config option.
966
967	  In normal configurations this driver is only active when needed:
968	  there's more than 3 GB of memory and the system contains a
969	  32-bit limited device.
970
971	  If unsure, say Y.
972
973config BOOT_VESA_SUPPORT
974	bool
975	help
976	  If true, at least one selected framebuffer driver can take advantage
977	  of VESA video modes set at an early boot stage via the vga= parameter.
978
979config MAXSMP
980	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
981	depends on X86_64 && SMP && DEBUG_KERNEL
982	select CPUMASK_OFFSTACK
983	help
984	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
985	  If unsure, say N.
986
987#
988# The maximum number of CPUs supported:
989#
990# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
991# and which can be configured interactively in the
992# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
993#
994# The ranges are different on 32-bit and 64-bit kernels, depending on
995# hardware capabilities and scalability features of the kernel.
996#
997# ( If MAXSMP is enabled we just use the highest possible value and disable
998#   interactive configuration. )
999#
1000
1001config NR_CPUS_RANGE_BEGIN
1002	int
1003	default NR_CPUS_RANGE_END if MAXSMP
1004	default    1 if !SMP
1005	default    2
1006
1007config NR_CPUS_RANGE_END
1008	int
1009	depends on X86_32
1010	default   64 if  SMP &&  X86_BIGSMP
1011	default    8 if  SMP && !X86_BIGSMP
1012	default    1 if !SMP
1013
1014config NR_CPUS_RANGE_END
1015	int
1016	depends on X86_64
1017	default 8192 if  SMP && CPUMASK_OFFSTACK
1018	default  512 if  SMP && !CPUMASK_OFFSTACK
1019	default    1 if !SMP
1020
1021config NR_CPUS_DEFAULT
1022	int
1023	depends on X86_32
1024	default   32 if  X86_BIGSMP
1025	default    8 if  SMP
1026	default    1 if !SMP
1027
1028config NR_CPUS_DEFAULT
1029	int
1030	depends on X86_64
1031	default 8192 if  MAXSMP
1032	default   64 if  SMP
1033	default    1 if !SMP
1034
1035config NR_CPUS
1036	int "Maximum number of CPUs" if SMP && !MAXSMP
1037	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1038	default NR_CPUS_DEFAULT
1039	help
1040	  This allows you to specify the maximum number of CPUs which this
1041	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1042	  supported value is 8192, otherwise the maximum value is 512.  The
1043	  minimum value which makes sense is 2.
1044
1045	  This is purely to save memory: each supported CPU adds about 8KB
1046	  to the kernel image.
1047
1048config SCHED_CLUSTER
1049	bool "Cluster scheduler support"
1050	depends on SMP
1051	default y
1052	help
1053	  Cluster scheduler support improves the CPU scheduler's decision
1054	  making when dealing with machines that have clusters of CPUs.
1055	  Cluster usually means a couple of CPUs which are placed closely
1056	  by sharing mid-level caches, last-level cache tags or internal
1057	  busses.
1058
1059config SCHED_SMT
1060	def_bool y if SMP
1061
1062config SCHED_MC
1063	def_bool y
1064	prompt "Multi-core scheduler support"
1065	depends on SMP
1066	help
1067	  Multi-core scheduler support improves the CPU scheduler's decision
1068	  making when dealing with multi-core CPU chips at a cost of slightly
1069	  increased overhead in some places. If unsure say N here.
1070
1071config SCHED_MC_PRIO
1072	bool "CPU core priorities scheduler support"
1073	depends on SCHED_MC
1074	select X86_INTEL_PSTATE if CPU_SUP_INTEL
1075	select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
1076	select CPU_FREQ
1077	default y
1078	help
1079	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1080	  core ordering determined at manufacturing time, which allows
1081	  certain cores to reach higher turbo frequencies (when running
1082	  single threaded workloads) than others.
1083
1084	  Enabling this kernel feature teaches the scheduler about
1085	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1086	  scheduler's CPU selection logic accordingly, so that higher
1087	  overall system performance can be achieved.
1088
1089	  This feature will have no effect on CPUs without this feature.
1090
1091	  If unsure say Y here.
1092
1093config UP_LATE_INIT
1094	def_bool y
1095	depends on !SMP && X86_LOCAL_APIC
1096
1097config X86_UP_APIC
1098	bool "Local APIC support on uniprocessors" if !PCI_MSI
1099	default PCI_MSI
1100	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1101	help
1102	  A local APIC (Advanced Programmable Interrupt Controller) is an
1103	  integrated interrupt controller in the CPU. If you have a single-CPU
1104	  system which has a processor with a local APIC, you can say Y here to
1105	  enable and use it. If you say Y here even though your machine doesn't
1106	  have a local APIC, then the kernel will still run with no slowdown at
1107	  all. The local APIC supports CPU-generated self-interrupts (timer,
1108	  performance counters), and the NMI watchdog which detects hard
1109	  lockups.
1110
1111config X86_UP_IOAPIC
1112	bool "IO-APIC support on uniprocessors"
1113	depends on X86_UP_APIC
1114	help
1115	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1116	  SMP-capable replacement for PC-style interrupt controllers. Most
1117	  SMP systems and many recent uniprocessor systems have one.
1118
1119	  If you have a single-CPU system with an IO-APIC, you can say Y here
1120	  to use it. If you say Y here even though your machine doesn't have
1121	  an IO-APIC, then the kernel will still run with no slowdown at all.
1122
1123config X86_LOCAL_APIC
1124	def_bool y
1125	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1126	select IRQ_DOMAIN_HIERARCHY
1127
1128config ACPI_MADT_WAKEUP
1129	def_bool y
1130	depends on X86_64
1131	depends on ACPI
1132	depends on SMP
1133	depends on X86_LOCAL_APIC
1134
1135config X86_IO_APIC
1136	def_bool y
1137	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1138
1139config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1140	bool "Reroute for broken boot IRQs"
1141	depends on X86_IO_APIC
1142	help
1143	  This option enables a workaround that fixes a source of
1144	  spurious interrupts. This is recommended when threaded
1145	  interrupt handling is used on systems where the generation of
1146	  superfluous "boot interrupts" cannot be disabled.
1147
1148	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1149	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1150	  kernel does during interrupt handling). On chipsets where this
1151	  boot IRQ generation cannot be disabled, this workaround keeps
1152	  the original IRQ line masked so that only the equivalent "boot
1153	  IRQ" is delivered to the CPUs. The workaround also tells the
1154	  kernel to set up the IRQ handler on the boot IRQ line. In this
1155	  way only one interrupt is delivered to the kernel. Otherwise
1156	  the spurious second interrupt may cause the kernel to bring
1157	  down (vital) interrupt lines.
1158
1159	  Only affects "broken" chipsets. Interrupt sharing may be
1160	  increased on these systems.
1161
1162config X86_MCE
1163	bool "Machine Check / overheating reporting"
1164	select GENERIC_ALLOCATOR
1165	default y
1166	help
1167	  Machine Check support allows the processor to notify the
1168	  kernel if it detects a problem (e.g. overheating, data corruption).
1169	  The action the kernel takes depends on the severity of the problem,
1170	  ranging from warning messages to halting the machine.
1171
1172config X86_MCELOG_LEGACY
1173	bool "Support for deprecated /dev/mcelog character device"
1174	depends on X86_MCE
1175	help
1176	  Enable support for /dev/mcelog which is needed by the old mcelog
1177	  userspace logging daemon. Consider switching to the new generation
1178	  rasdaemon solution.
1179
1180config X86_MCE_INTEL
1181	def_bool y
1182	prompt "Intel MCE features"
1183	depends on X86_MCE && X86_LOCAL_APIC
1184	help
1185	  Additional support for intel specific MCE features such as
1186	  the thermal monitor.
1187
1188config X86_MCE_AMD
1189	def_bool y
1190	prompt "AMD MCE features"
1191	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1192	help
1193	  Additional support for AMD specific MCE features such as
1194	  the DRAM Error Threshold.
1195
1196config X86_ANCIENT_MCE
1197	bool "Support for old Pentium 5 / WinChip machine checks"
1198	depends on X86_32 && X86_MCE
1199	help
1200	  Include support for machine check handling on old Pentium 5 or WinChip
1201	  systems. These typically need to be enabled explicitly on the command
1202	  line.
1203
1204config X86_MCE_THRESHOLD
1205	depends on X86_MCE_AMD || X86_MCE_INTEL
1206	def_bool y
1207
1208config X86_MCE_INJECT
1209	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1210	tristate "Machine check injector support"
1211	help
1212	  Provide support for injecting machine checks for testing purposes.
1213	  If you don't know what a machine check is and you don't do kernel
1214	  QA it is safe to say n.
1215
1216source "arch/x86/events/Kconfig"
1217
1218config X86_LEGACY_VM86
1219	bool "Legacy VM86 support"
1220	depends on X86_32
1221	help
1222	  This option allows user programs to put the CPU into V8086
1223	  mode, which is an 80286-era approximation of 16-bit real mode.
1224
1225	  Some very old versions of X and/or vbetool require this option
1226	  for user mode setting.  Similarly, DOSEMU will use it if
1227	  available to accelerate real mode DOS programs.  However, any
1228	  recent version of DOSEMU, X, or vbetool should be fully
1229	  functional even without kernel VM86 support, as they will all
1230	  fall back to software emulation. Nevertheless, if you are using
1231	  a 16-bit DOS program where 16-bit performance matters, vm86
1232	  mode might be faster than emulation and you might want to
1233	  enable this option.
1234
1235	  Note that any app that works on a 64-bit kernel is unlikely to
1236	  need this option, as 64-bit kernels don't, and can't, support
1237	  V8086 mode. This option is also unrelated to 16-bit protected
1238	  mode and is not needed to run most 16-bit programs under Wine.
1239
1240	  Enabling this option increases the complexity of the kernel
1241	  and slows down exception handling a tiny bit.
1242
1243	  If unsure, say N here.
1244
1245config VM86
1246	bool
1247	default X86_LEGACY_VM86
1248
1249config X86_16BIT
1250	bool "Enable support for 16-bit segments" if EXPERT
1251	default y
1252	depends on MODIFY_LDT_SYSCALL
1253	help
1254	  This option is required by programs like Wine to run 16-bit
1255	  protected mode legacy code on x86 processors.  Disabling
1256	  this option saves about 300 bytes on i386, or around 6K text
1257	  plus 16K runtime memory on x86-64,
1258
1259config X86_ESPFIX32
1260	def_bool y
1261	depends on X86_16BIT && X86_32
1262
1263config X86_ESPFIX64
1264	def_bool y
1265	depends on X86_16BIT && X86_64
1266
1267config X86_VSYSCALL_EMULATION
1268	bool "Enable vsyscall emulation" if EXPERT
1269	default y
1270	depends on X86_64
1271	help
1272	  This enables emulation of the legacy vsyscall page.  Disabling
1273	  it is roughly equivalent to booting with vsyscall=none, except
1274	  that it will also disable the helpful warning if a program
1275	  tries to use a vsyscall.  With this option set to N, offending
1276	  programs will just segfault, citing addresses of the form
1277	  0xffffffffff600?00.
1278
1279	  This option is required by many programs built before 2013, and
1280	  care should be used even with newer programs if set to N.
1281
1282	  Disabling this option saves about 7K of kernel size and
1283	  possibly 4K of additional runtime pagetable memory.
1284
1285config X86_IOPL_IOPERM
1286	bool "IOPERM and IOPL Emulation"
1287	default y
1288	help
1289	  This enables the ioperm() and iopl() syscalls which are necessary
1290	  for legacy applications.
1291
1292	  Legacy IOPL support is an overbroad mechanism which allows user
1293	  space aside of accessing all 65536 I/O ports also to disable
1294	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1295	  capabilities and permission from potentially active security
1296	  modules.
1297
1298	  The emulation restricts the functionality of the syscall to
1299	  only allowing the full range I/O port access, but prevents the
1300	  ability to disable interrupts from user space which would be
1301	  granted if the hardware IOPL mechanism would be used.
1302
1303config TOSHIBA
1304	tristate "Toshiba Laptop support"
1305	depends on X86_32
1306	help
1307	  This adds a driver to safely access the System Management Mode of
1308	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1309	  not work on models with a Phoenix BIOS. The System Management Mode
1310	  is used to set the BIOS and power saving options on Toshiba portables.
1311
1312	  For information on utilities to make use of this driver see the
1313	  Toshiba Linux utilities web site at:
1314	  <http://www.buzzard.org.uk/toshiba/>.
1315
1316	  Say Y if you intend to run this kernel on a Toshiba portable.
1317	  Say N otherwise.
1318
1319config X86_REBOOTFIXUPS
1320	bool "Enable X86 board specific fixups for reboot"
1321	depends on X86_32
1322	help
1323	  This enables chipset and/or board specific fixups to be done
1324	  in order to get reboot to work correctly. This is only needed on
1325	  some combinations of hardware and BIOS. The symptom, for which
1326	  this config is intended, is when reboot ends with a stalled/hung
1327	  system.
1328
1329	  Currently, the only fixup is for the Geode machines using
1330	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1331
1332	  Say Y if you want to enable the fixup. Currently, it's safe to
1333	  enable this option even if you don't need it.
1334	  Say N otherwise.
1335
1336config MICROCODE
1337	def_bool y
1338	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1339
1340config MICROCODE_INITRD32
1341	def_bool y
1342	depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1343
1344config MICROCODE_LATE_LOADING
1345	bool "Late microcode loading (DANGEROUS)"
1346	default n
1347	depends on MICROCODE && SMP
1348	help
1349	  Loading microcode late, when the system is up and executing instructions
1350	  is a tricky business and should be avoided if possible. Just the sequence
1351	  of synchronizing all cores and SMT threads is one fragile dance which does
1352	  not guarantee that cores might not softlock after the loading. Therefore,
1353	  use this at your own risk. Late loading taints the kernel unless the
1354	  microcode header indicates that it is safe for late loading via the
1355	  minimal revision check. This minimal revision check can be enforced on
1356	  the kernel command line with "microcode.minrev=Y".
1357
1358config MICROCODE_LATE_FORCE_MINREV
1359	bool "Enforce late microcode loading minimal revision check"
1360	default n
1361	depends on MICROCODE_LATE_LOADING
1362	help
1363	  To prevent that users load microcode late which modifies already
1364	  in use features, newer microcode patches have a minimum revision field
1365	  in the microcode header, which tells the kernel which minimum
1366	  revision must be active in the CPU to safely load that new microcode
1367	  late into the running system. If disabled the check will not
1368	  be enforced but the kernel will be tainted when the minimal
1369	  revision check fails.
1370
1371	  This minimal revision check can also be controlled via the
1372	  "microcode.minrev" parameter on the kernel command line.
1373
1374	  If unsure say Y.
1375
1376config X86_MSR
1377	tristate "/dev/cpu/*/msr - Model-specific register support"
1378	help
1379	  This device gives privileged processes access to the x86
1380	  Model-Specific Registers (MSRs).  It is a character device with
1381	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1382	  MSR accesses are directed to a specific CPU on multi-processor
1383	  systems.
1384
1385config X86_CPUID
1386	tristate "/dev/cpu/*/cpuid - CPU information support"
1387	help
1388	  This device gives processes access to the x86 CPUID instruction to
1389	  be executed on a specific processor.  It is a character device
1390	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1391	  /dev/cpu/31/cpuid.
1392
1393choice
1394	prompt "High Memory Support"
1395	default HIGHMEM4G
1396	depends on X86_32
1397
1398config NOHIGHMEM
1399	bool "off"
1400	help
1401	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1402	  However, the address space of 32-bit x86 processors is only 4
1403	  Gigabytes large. That means that, if you have a large amount of
1404	  physical memory, not all of it can be "permanently mapped" by the
1405	  kernel. The physical memory that's not permanently mapped is called
1406	  "high memory".
1407
1408	  If you are compiling a kernel which will never run on a machine with
1409	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1410	  choice and suitable for most users). This will result in a "3GB/1GB"
1411	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1412	  space and the remaining part of the 4GB virtual memory space is used
1413	  by the kernel to permanently map as much physical memory as
1414	  possible.
1415
1416	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1417	  answer "4GB" here.
1418
1419	  If more than 4 Gigabytes is used then answer "64GB" here. This
1420	  selection turns Intel PAE (Physical Address Extension) mode on.
1421	  PAE implements 3-level paging on IA32 processors. PAE is fully
1422	  supported by Linux, PAE mode is implemented on all recent Intel
1423	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1424	  then the kernel will not boot on CPUs that don't support PAE!
1425
1426	  The actual amount of total physical memory will either be
1427	  auto detected or can be forced by using a kernel command line option
1428	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1429	  your boot loader (lilo or loadlin) about how to pass options to the
1430	  kernel at boot time.)
1431
1432	  If unsure, say "off".
1433
1434config HIGHMEM4G
1435	bool "4GB"
1436	help
1437	  Select this if you have a 32-bit processor and between 1 and 4
1438	  gigabytes of physical RAM.
1439
1440config HIGHMEM64G
1441	bool "64GB"
1442	depends on X86_HAVE_PAE
1443	select X86_PAE
1444	help
1445	  Select this if you have a 32-bit processor and more than 4
1446	  gigabytes of physical RAM.
1447
1448endchoice
1449
1450choice
1451	prompt "Memory split" if EXPERT
1452	default VMSPLIT_3G
1453	depends on X86_32
1454	help
1455	  Select the desired split between kernel and user memory.
1456
1457	  If the address range available to the kernel is less than the
1458	  physical memory installed, the remaining memory will be available
1459	  as "high memory". Accessing high memory is a little more costly
1460	  than low memory, as it needs to be mapped into the kernel first.
1461	  Note that increasing the kernel address space limits the range
1462	  available to user programs, making the address space there
1463	  tighter.  Selecting anything other than the default 3G/1G split
1464	  will also likely make your kernel incompatible with binary-only
1465	  kernel modules.
1466
1467	  If you are not absolutely sure what you are doing, leave this
1468	  option alone!
1469
1470	config VMSPLIT_3G
1471		bool "3G/1G user/kernel split"
1472	config VMSPLIT_3G_OPT
1473		depends on !X86_PAE
1474		bool "3G/1G user/kernel split (for full 1G low memory)"
1475	config VMSPLIT_2G
1476		bool "2G/2G user/kernel split"
1477	config VMSPLIT_2G_OPT
1478		depends on !X86_PAE
1479		bool "2G/2G user/kernel split (for full 2G low memory)"
1480	config VMSPLIT_1G
1481		bool "1G/3G user/kernel split"
1482endchoice
1483
1484config PAGE_OFFSET
1485	hex
1486	default 0xB0000000 if VMSPLIT_3G_OPT
1487	default 0x80000000 if VMSPLIT_2G
1488	default 0x78000000 if VMSPLIT_2G_OPT
1489	default 0x40000000 if VMSPLIT_1G
1490	default 0xC0000000
1491	depends on X86_32
1492
1493config HIGHMEM
1494	def_bool y
1495	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1496
1497config X86_PAE
1498	bool "PAE (Physical Address Extension) Support"
1499	depends on X86_32 && X86_HAVE_PAE
1500	select PHYS_ADDR_T_64BIT
1501	select SWIOTLB
1502	help
1503	  PAE is required for NX support, and furthermore enables
1504	  larger swapspace support for non-overcommit purposes. It
1505	  has the cost of more pagetable lookup overhead, and also
1506	  consumes more pagetable space per process.
1507
1508config X86_5LEVEL
1509	bool "Enable 5-level page tables support"
1510	default y
1511	select DYNAMIC_MEMORY_LAYOUT
1512	select SPARSEMEM_VMEMMAP
1513	depends on X86_64
1514	help
1515	  5-level paging enables access to larger address space:
1516	  up to 128 PiB of virtual address space and 4 PiB of
1517	  physical address space.
1518
1519	  It will be supported by future Intel CPUs.
1520
1521	  A kernel with the option enabled can be booted on machines that
1522	  support 4- or 5-level paging.
1523
1524	  See Documentation/arch/x86/x86_64/5level-paging.rst for more
1525	  information.
1526
1527	  Say N if unsure.
1528
1529config X86_DIRECT_GBPAGES
1530	def_bool y
1531	depends on X86_64
1532	help
1533	  Certain kernel features effectively disable kernel
1534	  linear 1 GB mappings (even if the CPU otherwise
1535	  supports them), so don't confuse the user by printing
1536	  that we have them enabled.
1537
1538config X86_CPA_STATISTICS
1539	bool "Enable statistic for Change Page Attribute"
1540	depends on DEBUG_FS
1541	help
1542	  Expose statistics about the Change Page Attribute mechanism, which
1543	  helps to determine the effectiveness of preserving large and huge
1544	  page mappings when mapping protections are changed.
1545
1546config X86_MEM_ENCRYPT
1547	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1548	select DYNAMIC_PHYSICAL_MASK
1549	def_bool n
1550
1551config AMD_MEM_ENCRYPT
1552	bool "AMD Secure Memory Encryption (SME) support"
1553	depends on X86_64 && CPU_SUP_AMD
1554	depends on EFI_STUB
1555	select DMA_COHERENT_POOL
1556	select ARCH_USE_MEMREMAP_PROT
1557	select INSTRUCTION_DECODER
1558	select ARCH_HAS_CC_PLATFORM
1559	select X86_MEM_ENCRYPT
1560	select UNACCEPTED_MEMORY
1561	help
1562	  Say yes to enable support for the encryption of system memory.
1563	  This requires an AMD processor that supports Secure Memory
1564	  Encryption (SME).
1565
1566# Common NUMA Features
1567config NUMA
1568	bool "NUMA Memory Allocation and Scheduler Support"
1569	depends on SMP
1570	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1571	default y if X86_BIGSMP
1572	select USE_PERCPU_NUMA_NODE_ID
1573	select OF_NUMA if OF
1574	help
1575	  Enable NUMA (Non-Uniform Memory Access) support.
1576
1577	  The kernel will try to allocate memory used by a CPU on the
1578	  local memory controller of the CPU and add some more
1579	  NUMA awareness to the kernel.
1580
1581	  For 64-bit this is recommended if the system is Intel Core i7
1582	  (or later), AMD Opteron, or EM64T NUMA.
1583
1584	  For 32-bit this is only needed if you boot a 32-bit
1585	  kernel on a 64-bit NUMA platform.
1586
1587	  Otherwise, you should say N.
1588
1589config AMD_NUMA
1590	def_bool y
1591	prompt "Old style AMD Opteron NUMA detection"
1592	depends on X86_64 && NUMA && PCI
1593	help
1594	  Enable AMD NUMA node topology detection.  You should say Y here if
1595	  you have a multi processor AMD system. This uses an old method to
1596	  read the NUMA configuration directly from the builtin Northbridge
1597	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1598	  which also takes priority if both are compiled in.
1599
1600config X86_64_ACPI_NUMA
1601	def_bool y
1602	prompt "ACPI NUMA detection"
1603	depends on X86_64 && NUMA && ACPI && PCI
1604	select ACPI_NUMA
1605	help
1606	  Enable ACPI SRAT based node topology detection.
1607
1608config NODES_SHIFT
1609	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1610	range 1 10
1611	default "10" if MAXSMP
1612	default "6" if X86_64
1613	default "3"
1614	depends on NUMA
1615	help
1616	  Specify the maximum number of NUMA Nodes available on the target
1617	  system.  Increases memory reserved to accommodate various tables.
1618
1619config ARCH_FLATMEM_ENABLE
1620	def_bool y
1621	depends on X86_32 && !NUMA
1622
1623config ARCH_SPARSEMEM_ENABLE
1624	def_bool y
1625	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1626	select SPARSEMEM_STATIC if X86_32
1627	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1628
1629config ARCH_SPARSEMEM_DEFAULT
1630	def_bool X86_64 || (NUMA && X86_32)
1631
1632config ARCH_SELECT_MEMORY_MODEL
1633	def_bool y
1634	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1635
1636config ARCH_MEMORY_PROBE
1637	bool "Enable sysfs memory/probe interface"
1638	depends on MEMORY_HOTPLUG
1639	help
1640	  This option enables a sysfs memory/probe interface for testing.
1641	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1642	  If you are unsure how to answer this question, answer N.
1643
1644config ARCH_PROC_KCORE_TEXT
1645	def_bool y
1646	depends on X86_64 && PROC_KCORE
1647
1648config ILLEGAL_POINTER_VALUE
1649	hex
1650	default 0 if X86_32
1651	default 0xdead000000000000 if X86_64
1652
1653config X86_PMEM_LEGACY_DEVICE
1654	bool
1655
1656config X86_PMEM_LEGACY
1657	tristate "Support non-standard NVDIMMs and ADR protected memory"
1658	depends on PHYS_ADDR_T_64BIT
1659	depends on BLK_DEV
1660	select X86_PMEM_LEGACY_DEVICE
1661	select NUMA_KEEP_MEMINFO if NUMA
1662	select LIBNVDIMM
1663	help
1664	  Treat memory marked using the non-standard e820 type of 12 as used
1665	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1666	  The kernel will offer these regions to the 'pmem' driver so
1667	  they can be used for persistent storage.
1668
1669	  Say Y if unsure.
1670
1671config HIGHPTE
1672	bool "Allocate 3rd-level pagetables from highmem"
1673	depends on HIGHMEM
1674	help
1675	  The VM uses one page table entry for each page of physical memory.
1676	  For systems with a lot of RAM, this can be wasteful of precious
1677	  low memory.  Setting this option will put user-space page table
1678	  entries in high memory.
1679
1680config X86_CHECK_BIOS_CORRUPTION
1681	bool "Check for low memory corruption"
1682	help
1683	  Periodically check for memory corruption in low memory, which
1684	  is suspected to be caused by BIOS.  Even when enabled in the
1685	  configuration, it is disabled at runtime.  Enable it by
1686	  setting "memory_corruption_check=1" on the kernel command
1687	  line.  By default it scans the low 64k of memory every 60
1688	  seconds; see the memory_corruption_check_size and
1689	  memory_corruption_check_period parameters in
1690	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1691
1692	  When enabled with the default parameters, this option has
1693	  almost no overhead, as it reserves a relatively small amount
1694	  of memory and scans it infrequently.  It both detects corruption
1695	  and prevents it from affecting the running system.
1696
1697	  It is, however, intended as a diagnostic tool; if repeatable
1698	  BIOS-originated corruption always affects the same memory,
1699	  you can use memmap= to prevent the kernel from using that
1700	  memory.
1701
1702config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1703	bool "Set the default setting of memory_corruption_check"
1704	depends on X86_CHECK_BIOS_CORRUPTION
1705	default y
1706	help
1707	  Set whether the default state of memory_corruption_check is
1708	  on or off.
1709
1710config MATH_EMULATION
1711	bool
1712	depends on MODIFY_LDT_SYSCALL
1713	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1714	help
1715	  Linux can emulate a math coprocessor (used for floating point
1716	  operations) if you don't have one. 486DX and Pentium processors have
1717	  a math coprocessor built in, 486SX and 386 do not, unless you added
1718	  a 487DX or 387, respectively. (The messages during boot time can
1719	  give you some hints here ["man dmesg"].) Everyone needs either a
1720	  coprocessor or this emulation.
1721
1722	  If you don't have a math coprocessor, you need to say Y here; if you
1723	  say Y here even though you have a coprocessor, the coprocessor will
1724	  be used nevertheless. (This behavior can be changed with the kernel
1725	  command line option "no387", which comes handy if your coprocessor
1726	  is broken. Try "man bootparam" or see the documentation of your boot
1727	  loader (lilo or loadlin) about how to pass options to the kernel at
1728	  boot time.) This means that it is a good idea to say Y here if you
1729	  intend to use this kernel on different machines.
1730
1731	  More information about the internals of the Linux math coprocessor
1732	  emulation can be found in <file:arch/x86/math-emu/README>.
1733
1734	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1735	  kernel, it won't hurt.
1736
1737config MTRR
1738	def_bool y
1739	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1740	help
1741	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1742	  the Memory Type Range Registers (MTRRs) may be used to control
1743	  processor access to memory ranges. This is most useful if you have
1744	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1745	  allows bus write transfers to be combined into a larger transfer
1746	  before bursting over the PCI/AGP bus. This can increase performance
1747	  of image write operations 2.5 times or more. Saying Y here creates a
1748	  /proc/mtrr file which may be used to manipulate your processor's
1749	  MTRRs. Typically the X server should use this.
1750
1751	  This code has a reasonably generic interface so that similar
1752	  control registers on other processors can be easily supported
1753	  as well:
1754
1755	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1756	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1757	  these, the ARRs are used to emulate the MTRRs.
1758	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1759	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1760	  write-combining. All of these processors are supported by this code
1761	  and it makes sense to say Y here if you have one of them.
1762
1763	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1764	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1765	  can lead to all sorts of problems, so it's good to say Y here.
1766
1767	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1768	  just add about 9 KB to your kernel.
1769
1770	  See <file:Documentation/arch/x86/mtrr.rst> for more information.
1771
1772config MTRR_SANITIZER
1773	def_bool y
1774	prompt "MTRR cleanup support"
1775	depends on MTRR
1776	help
1777	  Convert MTRR layout from continuous to discrete, so X drivers can
1778	  add writeback entries.
1779
1780	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1781	  The largest mtrr entry size for a continuous block can be set with
1782	  mtrr_chunk_size.
1783
1784	  If unsure, say Y.
1785
1786config MTRR_SANITIZER_ENABLE_DEFAULT
1787	int "MTRR cleanup enable value (0-1)"
1788	range 0 1
1789	default "0"
1790	depends on MTRR_SANITIZER
1791	help
1792	  Enable mtrr cleanup default value
1793
1794config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1795	int "MTRR cleanup spare reg num (0-7)"
1796	range 0 7
1797	default "1"
1798	depends on MTRR_SANITIZER
1799	help
1800	  mtrr cleanup spare entries default, it can be changed via
1801	  mtrr_spare_reg_nr=N on the kernel command line.
1802
1803config X86_PAT
1804	def_bool y
1805	prompt "x86 PAT support" if EXPERT
1806	depends on MTRR
1807	select ARCH_USES_PG_ARCH_2
1808	help
1809	  Use PAT attributes to setup page level cache control.
1810
1811	  PATs are the modern equivalents of MTRRs and are much more
1812	  flexible than MTRRs.
1813
1814	  Say N here if you see bootup problems (boot crash, boot hang,
1815	  spontaneous reboots) or a non-working video driver.
1816
1817	  If unsure, say Y.
1818
1819config X86_UMIP
1820	def_bool y
1821	prompt "User Mode Instruction Prevention" if EXPERT
1822	help
1823	  User Mode Instruction Prevention (UMIP) is a security feature in
1824	  some x86 processors. If enabled, a general protection fault is
1825	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1826	  executed in user mode. These instructions unnecessarily expose
1827	  information about the hardware state.
1828
1829	  The vast majority of applications do not use these instructions.
1830	  For the very few that do, software emulation is provided in
1831	  specific cases in protected and virtual-8086 modes. Emulated
1832	  results are dummy.
1833
1834config CC_HAS_IBT
1835	# GCC >= 9 and binutils >= 2.29
1836	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1837	# Clang/LLVM >= 14
1838	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1839	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1840	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1841		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1842		  $(as-instr,endbr64)
1843
1844config X86_CET
1845	def_bool n
1846	help
1847	  CET features configured (Shadow stack or IBT)
1848
1849config X86_KERNEL_IBT
1850	prompt "Indirect Branch Tracking"
1851	def_bool y
1852	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1853	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1854	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1855	select OBJTOOL
1856	select X86_CET
1857	help
1858	  Build the kernel with support for Indirect Branch Tracking, a
1859	  hardware support course-grain forward-edge Control Flow Integrity
1860	  protection. It enforces that all indirect calls must land on
1861	  an ENDBR instruction, as such, the compiler will instrument the
1862	  code with them to make this happen.
1863
1864	  In addition to building the kernel with IBT, seal all functions that
1865	  are not indirect call targets, avoiding them ever becoming one.
1866
1867	  This requires LTO like objtool runs and will slow down the build. It
1868	  does significantly reduce the number of ENDBR instructions in the
1869	  kernel image.
1870
1871config X86_INTEL_MEMORY_PROTECTION_KEYS
1872	prompt "Memory Protection Keys"
1873	def_bool y
1874	# Note: only available in 64-bit mode
1875	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1876	select ARCH_USES_HIGH_VMA_FLAGS
1877	select ARCH_HAS_PKEYS
1878	help
1879	  Memory Protection Keys provides a mechanism for enforcing
1880	  page-based protections, but without requiring modification of the
1881	  page tables when an application changes protection domains.
1882
1883	  For details, see Documentation/core-api/protection-keys.rst
1884
1885	  If unsure, say y.
1886
1887config ARCH_PKEY_BITS
1888	int
1889	default 4
1890
1891choice
1892	prompt "TSX enable mode"
1893	depends on CPU_SUP_INTEL
1894	default X86_INTEL_TSX_MODE_OFF
1895	help
1896	  Intel's TSX (Transactional Synchronization Extensions) feature
1897	  allows to optimize locking protocols through lock elision which
1898	  can lead to a noticeable performance boost.
1899
1900	  On the other hand it has been shown that TSX can be exploited
1901	  to form side channel attacks (e.g. TAA) and chances are there
1902	  will be more of those attacks discovered in the future.
1903
1904	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1905	  might override this decision by tsx=on the command line parameter.
1906	  Even with TSX enabled, the kernel will attempt to enable the best
1907	  possible TAA mitigation setting depending on the microcode available
1908	  for the particular machine.
1909
1910	  This option allows to set the default tsx mode between tsx=on, =off
1911	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1912	  details.
1913
1914	  Say off if not sure, auto if TSX is in use but it should be used on safe
1915	  platforms or on if TSX is in use and the security aspect of tsx is not
1916	  relevant.
1917
1918config X86_INTEL_TSX_MODE_OFF
1919	bool "off"
1920	help
1921	  TSX is disabled if possible - equals to tsx=off command line parameter.
1922
1923config X86_INTEL_TSX_MODE_ON
1924	bool "on"
1925	help
1926	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1927	  line parameter.
1928
1929config X86_INTEL_TSX_MODE_AUTO
1930	bool "auto"
1931	help
1932	  TSX is enabled on TSX capable HW that is believed to be safe against
1933	  side channel attacks- equals the tsx=auto command line parameter.
1934endchoice
1935
1936config X86_SGX
1937	bool "Software Guard eXtensions (SGX)"
1938	depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1939	depends on CRYPTO=y
1940	depends on CRYPTO_SHA256=y
1941	select MMU_NOTIFIER
1942	select NUMA_KEEP_MEMINFO if NUMA
1943	select XARRAY_MULTI
1944	help
1945	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1946	  that can be used by applications to set aside private regions of code
1947	  and data, referred to as enclaves. An enclave's private memory can
1948	  only be accessed by code running within the enclave. Accesses from
1949	  outside the enclave, including other enclaves, are disallowed by
1950	  hardware.
1951
1952	  If unsure, say N.
1953
1954config X86_USER_SHADOW_STACK
1955	bool "X86 userspace shadow stack"
1956	depends on AS_WRUSS
1957	depends on X86_64
1958	select ARCH_USES_HIGH_VMA_FLAGS
1959	select X86_CET
1960	help
1961	  Shadow stack protection is a hardware feature that detects function
1962	  return address corruption.  This helps mitigate ROP attacks.
1963	  Applications must be enabled to use it, and old userspace does not
1964	  get protection "for free".
1965
1966	  CPUs supporting shadow stacks were first released in 2020.
1967
1968	  See Documentation/arch/x86/shstk.rst for more information.
1969
1970	  If unsure, say N.
1971
1972config INTEL_TDX_HOST
1973	bool "Intel Trust Domain Extensions (TDX) host support"
1974	depends on CPU_SUP_INTEL
1975	depends on X86_64
1976	depends on KVM_INTEL
1977	depends on X86_X2APIC
1978	select ARCH_KEEP_MEMBLOCK
1979	depends on CONTIG_ALLOC
1980	depends on !KEXEC_CORE
1981	depends on X86_MCE
1982	help
1983	  Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1984	  host and certain physical attacks.  This option enables necessary TDX
1985	  support in the host kernel to run confidential VMs.
1986
1987	  If unsure, say N.
1988
1989config EFI
1990	bool "EFI runtime service support"
1991	depends on ACPI
1992	select UCS2_STRING
1993	select EFI_RUNTIME_WRAPPERS
1994	select ARCH_USE_MEMREMAP_PROT
1995	select EFI_RUNTIME_MAP if KEXEC_CORE
1996	help
1997	  This enables the kernel to use EFI runtime services that are
1998	  available (such as the EFI variable services).
1999
2000	  This option is only useful on systems that have EFI firmware.
2001	  In addition, you should use the latest ELILO loader available
2002	  at <http://elilo.sourceforge.net> in order to take advantage
2003	  of EFI runtime services. However, even with this option, the
2004	  resultant kernel should continue to boot on existing non-EFI
2005	  platforms.
2006
2007config EFI_STUB
2008	bool "EFI stub support"
2009	depends on EFI
2010	select RELOCATABLE
2011	help
2012	  This kernel feature allows a bzImage to be loaded directly
2013	  by EFI firmware without the use of a bootloader.
2014
2015	  See Documentation/admin-guide/efi-stub.rst for more information.
2016
2017config EFI_HANDOVER_PROTOCOL
2018	bool "EFI handover protocol (DEPRECATED)"
2019	depends on EFI_STUB
2020	default y
2021	help
2022	  Select this in order to include support for the deprecated EFI
2023	  handover protocol, which defines alternative entry points into the
2024	  EFI stub.  This is a practice that has no basis in the UEFI
2025	  specification, and requires a priori knowledge on the part of the
2026	  bootloader about Linux/x86 specific ways of passing the command line
2027	  and initrd, and where in memory those assets may be loaded.
2028
2029	  If in doubt, say Y. Even though the corresponding support is not
2030	  present in upstream GRUB or other bootloaders, most distros build
2031	  GRUB with numerous downstream patches applied, and may rely on the
2032	  handover protocol as as result.
2033
2034config EFI_MIXED
2035	bool "EFI mixed-mode support"
2036	depends on EFI_STUB && X86_64
2037	help
2038	  Enabling this feature allows a 64-bit kernel to be booted
2039	  on a 32-bit firmware, provided that your CPU supports 64-bit
2040	  mode.
2041
2042	  Note that it is not possible to boot a mixed-mode enabled
2043	  kernel via the EFI boot stub - a bootloader that supports
2044	  the EFI handover protocol must be used.
2045
2046	  If unsure, say N.
2047
2048config EFI_RUNTIME_MAP
2049	bool "Export EFI runtime maps to sysfs" if EXPERT
2050	depends on EFI
2051	help
2052	  Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2053	  That memory map is required by the 2nd kernel to set up EFI virtual
2054	  mappings after kexec, but can also be used for debugging purposes.
2055
2056	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2057
2058source "kernel/Kconfig.hz"
2059
2060config ARCH_SUPPORTS_KEXEC
2061	def_bool y
2062
2063config ARCH_SUPPORTS_KEXEC_FILE
2064	def_bool X86_64
2065
2066config ARCH_SELECTS_KEXEC_FILE
2067	def_bool y
2068	depends on KEXEC_FILE
2069	select HAVE_IMA_KEXEC if IMA
2070
2071config ARCH_SUPPORTS_KEXEC_PURGATORY
2072	def_bool y
2073
2074config ARCH_SUPPORTS_KEXEC_SIG
2075	def_bool y
2076
2077config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2078	def_bool y
2079
2080config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2081	def_bool y
2082
2083config ARCH_SUPPORTS_KEXEC_JUMP
2084	def_bool y
2085
2086config ARCH_SUPPORTS_CRASH_DUMP
2087	def_bool X86_64 || (X86_32 && HIGHMEM)
2088
2089config ARCH_SUPPORTS_CRASH_HOTPLUG
2090	def_bool y
2091
2092config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2093	def_bool CRASH_RESERVE
2094
2095config PHYSICAL_START
2096	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2097	default "0x1000000"
2098	help
2099	  This gives the physical address where the kernel is loaded.
2100
2101	  If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2102	  will decompress itself to above physical address and run from there.
2103	  Otherwise, bzImage will run from the address where it has been loaded
2104	  by the boot loader. The only exception is if it is loaded below the
2105	  above physical address, in which case it will relocate itself there.
2106
2107	  In normal kdump cases one does not have to set/change this option
2108	  as now bzImage can be compiled as a completely relocatable image
2109	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2110	  address. This option is mainly useful for the folks who don't want
2111	  to use a bzImage for capturing the crash dump and want to use a
2112	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2113	  to be specifically compiled to run from a specific memory area
2114	  (normally a reserved region) and this option comes handy.
2115
2116	  So if you are using bzImage for capturing the crash dump,
2117	  leave the value here unchanged to 0x1000000 and set
2118	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2119	  for capturing the crash dump change this value to start of
2120	  the reserved region.  In other words, it can be set based on
2121	  the "X" value as specified in the "crashkernel=YM@XM"
2122	  command line boot parameter passed to the panic-ed
2123	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2124	  for more details about crash dumps.
2125
2126	  Usage of bzImage for capturing the crash dump is recommended as
2127	  one does not have to build two kernels. Same kernel can be used
2128	  as production kernel and capture kernel. Above option should have
2129	  gone away after relocatable bzImage support is introduced. But it
2130	  is present because there are users out there who continue to use
2131	  vmlinux for dump capture. This option should go away down the
2132	  line.
2133
2134	  Don't change this unless you know what you are doing.
2135
2136config RELOCATABLE
2137	bool "Build a relocatable kernel"
2138	default y
2139	help
2140	  This builds a kernel image that retains relocation information
2141	  so it can be loaded someplace besides the default 1MB.
2142	  The relocations tend to make the kernel binary about 10% larger,
2143	  but are discarded at runtime.
2144
2145	  One use is for the kexec on panic case where the recovery kernel
2146	  must live at a different physical address than the primary
2147	  kernel.
2148
2149	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2150	  it has been loaded at and the compile time physical address
2151	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2152
2153config RANDOMIZE_BASE
2154	bool "Randomize the address of the kernel image (KASLR)"
2155	depends on RELOCATABLE
2156	default y
2157	help
2158	  In support of Kernel Address Space Layout Randomization (KASLR),
2159	  this randomizes the physical address at which the kernel image
2160	  is decompressed and the virtual address where the kernel
2161	  image is mapped, as a security feature that deters exploit
2162	  attempts relying on knowledge of the location of kernel
2163	  code internals.
2164
2165	  On 64-bit, the kernel physical and virtual addresses are
2166	  randomized separately. The physical address will be anywhere
2167	  between 16MB and the top of physical memory (up to 64TB). The
2168	  virtual address will be randomized from 16MB up to 1GB (9 bits
2169	  of entropy). Note that this also reduces the memory space
2170	  available to kernel modules from 1.5GB to 1GB.
2171
2172	  On 32-bit, the kernel physical and virtual addresses are
2173	  randomized together. They will be randomized from 16MB up to
2174	  512MB (8 bits of entropy).
2175
2176	  Entropy is generated using the RDRAND instruction if it is
2177	  supported. If RDTSC is supported, its value is mixed into
2178	  the entropy pool as well. If neither RDRAND nor RDTSC are
2179	  supported, then entropy is read from the i8254 timer. The
2180	  usable entropy is limited by the kernel being built using
2181	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2182	  minimum of 2MB. As a result, only 10 bits of entropy are
2183	  theoretically possible, but the implementations are further
2184	  limited due to memory layouts.
2185
2186	  If unsure, say Y.
2187
2188# Relocation on x86 needs some additional build support
2189config X86_NEED_RELOCS
2190	def_bool y
2191	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2192
2193config PHYSICAL_ALIGN
2194	hex "Alignment value to which kernel should be aligned"
2195	default "0x200000"
2196	range 0x2000 0x1000000 if X86_32
2197	range 0x200000 0x1000000 if X86_64
2198	help
2199	  This value puts the alignment restrictions on physical address
2200	  where kernel is loaded and run from. Kernel is compiled for an
2201	  address which meets above alignment restriction.
2202
2203	  If bootloader loads the kernel at a non-aligned address and
2204	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2205	  address aligned to above value and run from there.
2206
2207	  If bootloader loads the kernel at a non-aligned address and
2208	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2209	  load address and decompress itself to the address it has been
2210	  compiled for and run from there. The address for which kernel is
2211	  compiled already meets above alignment restrictions. Hence the
2212	  end result is that kernel runs from a physical address meeting
2213	  above alignment restrictions.
2214
2215	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2216	  this value must be a multiple of 0x200000.
2217
2218	  Don't change this unless you know what you are doing.
2219
2220config DYNAMIC_MEMORY_LAYOUT
2221	bool
2222	help
2223	  This option makes base addresses of vmalloc and vmemmap as well as
2224	  __PAGE_OFFSET movable during boot.
2225
2226config RANDOMIZE_MEMORY
2227	bool "Randomize the kernel memory sections"
2228	depends on X86_64
2229	depends on RANDOMIZE_BASE
2230	select DYNAMIC_MEMORY_LAYOUT
2231	default RANDOMIZE_BASE
2232	help
2233	  Randomizes the base virtual address of kernel memory sections
2234	  (physical memory mapping, vmalloc & vmemmap). This security feature
2235	  makes exploits relying on predictable memory locations less reliable.
2236
2237	  The order of allocations remains unchanged. Entropy is generated in
2238	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2239	  configuration have in average 30,000 different possible virtual
2240	  addresses for each memory section.
2241
2242	  If unsure, say Y.
2243
2244config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2245	hex "Physical memory mapping padding" if EXPERT
2246	depends on RANDOMIZE_MEMORY
2247	default "0xa" if MEMORY_HOTPLUG
2248	default "0x0"
2249	range 0x1 0x40 if MEMORY_HOTPLUG
2250	range 0x0 0x40
2251	help
2252	  Define the padding in terabytes added to the existing physical
2253	  memory size during kernel memory randomization. It is useful
2254	  for memory hotplug support but reduces the entropy available for
2255	  address randomization.
2256
2257	  If unsure, leave at the default value.
2258
2259config ADDRESS_MASKING
2260	bool "Linear Address Masking support"
2261	depends on X86_64
2262	depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
2263	help
2264	  Linear Address Masking (LAM) modifies the checking that is applied
2265	  to 64-bit linear addresses, allowing software to use of the
2266	  untranslated address bits for metadata.
2267
2268	  The capability can be used for efficient address sanitizers (ASAN)
2269	  implementation and for optimizations in JITs.
2270
2271config HOTPLUG_CPU
2272	def_bool y
2273	depends on SMP
2274
2275config COMPAT_VDSO
2276	def_bool n
2277	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2278	depends on COMPAT_32
2279	help
2280	  Certain buggy versions of glibc will crash if they are
2281	  presented with a 32-bit vDSO that is not mapped at the address
2282	  indicated in its segment table.
2283
2284	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2285	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2286	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2287	  the only released version with the bug, but OpenSUSE 9
2288	  contains a buggy "glibc 2.3.2".
2289
2290	  The symptom of the bug is that everything crashes on startup, saying:
2291	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2292
2293	  Saying Y here changes the default value of the vdso32 boot
2294	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2295	  This works around the glibc bug but hurts performance.
2296
2297	  If unsure, say N: if you are compiling your own kernel, you
2298	  are unlikely to be using a buggy version of glibc.
2299
2300choice
2301	prompt "vsyscall table for legacy applications"
2302	depends on X86_64
2303	default LEGACY_VSYSCALL_XONLY
2304	help
2305	  Legacy user code that does not know how to find the vDSO expects
2306	  to be able to issue three syscalls by calling fixed addresses in
2307	  kernel space. Since this location is not randomized with ASLR,
2308	  it can be used to assist security vulnerability exploitation.
2309
2310	  This setting can be changed at boot time via the kernel command
2311	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2312	  is deprecated and can only be enabled using the kernel command
2313	  line.
2314
2315	  On a system with recent enough glibc (2.14 or newer) and no
2316	  static binaries, you can say None without a performance penalty
2317	  to improve security.
2318
2319	  If unsure, select "Emulate execution only".
2320
2321	config LEGACY_VSYSCALL_XONLY
2322		bool "Emulate execution only"
2323		help
2324		  The kernel traps and emulates calls into the fixed vsyscall
2325		  address mapping and does not allow reads.  This
2326		  configuration is recommended when userspace might use the
2327		  legacy vsyscall area but support for legacy binary
2328		  instrumentation of legacy code is not needed.  It mitigates
2329		  certain uses of the vsyscall area as an ASLR-bypassing
2330		  buffer.
2331
2332	config LEGACY_VSYSCALL_NONE
2333		bool "None"
2334		help
2335		  There will be no vsyscall mapping at all. This will
2336		  eliminate any risk of ASLR bypass due to the vsyscall
2337		  fixed address mapping. Attempts to use the vsyscalls
2338		  will be reported to dmesg, so that either old or
2339		  malicious userspace programs can be identified.
2340
2341endchoice
2342
2343config CMDLINE_BOOL
2344	bool "Built-in kernel command line"
2345	help
2346	  Allow for specifying boot arguments to the kernel at
2347	  build time.  On some systems (e.g. embedded ones), it is
2348	  necessary or convenient to provide some or all of the
2349	  kernel boot arguments with the kernel itself (that is,
2350	  to not rely on the boot loader to provide them.)
2351
2352	  To compile command line arguments into the kernel,
2353	  set this option to 'Y', then fill in the
2354	  boot arguments in CONFIG_CMDLINE.
2355
2356	  Systems with fully functional boot loaders (i.e. non-embedded)
2357	  should leave this option set to 'N'.
2358
2359config CMDLINE
2360	string "Built-in kernel command string"
2361	depends on CMDLINE_BOOL
2362	default ""
2363	help
2364	  Enter arguments here that should be compiled into the kernel
2365	  image and used at boot time.  If the boot loader provides a
2366	  command line at boot time, it is appended to this string to
2367	  form the full kernel command line, when the system boots.
2368
2369	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2370	  change this behavior.
2371
2372	  In most cases, the command line (whether built-in or provided
2373	  by the boot loader) should specify the device for the root
2374	  file system.
2375
2376config CMDLINE_OVERRIDE
2377	bool "Built-in command line overrides boot loader arguments"
2378	depends on CMDLINE_BOOL && CMDLINE != ""
2379	help
2380	  Set this option to 'Y' to have the kernel ignore the boot loader
2381	  command line, and use ONLY the built-in command line.
2382
2383	  This is used to work around broken boot loaders.  This should
2384	  be set to 'N' under normal conditions.
2385
2386config MODIFY_LDT_SYSCALL
2387	bool "Enable the LDT (local descriptor table)" if EXPERT
2388	default y
2389	help
2390	  Linux can allow user programs to install a per-process x86
2391	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2392	  call.  This is required to run 16-bit or segmented code such as
2393	  DOSEMU or some Wine programs.  It is also used by some very old
2394	  threading libraries.
2395
2396	  Enabling this feature adds a small amount of overhead to
2397	  context switches and increases the low-level kernel attack
2398	  surface.  Disabling it removes the modify_ldt(2) system call.
2399
2400	  Saying 'N' here may make sense for embedded or server kernels.
2401
2402config STRICT_SIGALTSTACK_SIZE
2403	bool "Enforce strict size checking for sigaltstack"
2404	depends on DYNAMIC_SIGFRAME
2405	help
2406	  For historical reasons MINSIGSTKSZ is a constant which became
2407	  already too small with AVX512 support. Add a mechanism to
2408	  enforce strict checking of the sigaltstack size against the
2409	  real size of the FPU frame. This option enables the check
2410	  by default. It can also be controlled via the kernel command
2411	  line option 'strict_sas_size' independent of this config
2412	  switch. Enabling it might break existing applications which
2413	  allocate a too small sigaltstack but 'work' because they
2414	  never get a signal delivered.
2415
2416	  Say 'N' unless you want to really enforce this check.
2417
2418config CFI_AUTO_DEFAULT
2419	bool "Attempt to use FineIBT by default at boot time"
2420	depends on FINEIBT
2421	default y
2422	help
2423	  Attempt to use FineIBT by default at boot time. If enabled,
2424	  this is the same as booting with "cfi=auto". If disabled,
2425	  this is the same as booting with "cfi=kcfi".
2426
2427source "kernel/livepatch/Kconfig"
2428
2429endmenu
2430
2431config CC_HAS_NAMED_AS
2432	def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
2433	depends on CC_IS_GCC
2434
2435config CC_HAS_NAMED_AS_FIXED_SANITIZERS
2436	def_bool CC_IS_GCC && GCC_VERSION >= 130300
2437
2438config USE_X86_SEG_SUPPORT
2439	def_bool y
2440	depends on CC_HAS_NAMED_AS
2441	#
2442	# -fsanitize=kernel-address (KASAN) and -fsanitize=thread
2443	# (KCSAN) are incompatible with named address spaces with
2444	# GCC < 13.3 - see GCC PR sanitizer/111736.
2445	#
2446	depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS
2447
2448config CC_HAS_SLS
2449	def_bool $(cc-option,-mharden-sls=all)
2450
2451config CC_HAS_RETURN_THUNK
2452	def_bool $(cc-option,-mfunction-return=thunk-extern)
2453
2454config CC_HAS_ENTRY_PADDING
2455	def_bool $(cc-option,-fpatchable-function-entry=16,16)
2456
2457config FUNCTION_PADDING_CFI
2458	int
2459	default 59 if FUNCTION_ALIGNMENT_64B
2460	default 27 if FUNCTION_ALIGNMENT_32B
2461	default 11 if FUNCTION_ALIGNMENT_16B
2462	default  3 if FUNCTION_ALIGNMENT_8B
2463	default  0
2464
2465# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2466# except Kconfig can't do arithmetic :/
2467config FUNCTION_PADDING_BYTES
2468	int
2469	default FUNCTION_PADDING_CFI if CFI_CLANG
2470	default FUNCTION_ALIGNMENT
2471
2472config CALL_PADDING
2473	def_bool n
2474	depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2475	select FUNCTION_ALIGNMENT_16B
2476
2477config FINEIBT
2478	def_bool y
2479	depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2480	select CALL_PADDING
2481
2482config HAVE_CALL_THUNKS
2483	def_bool y
2484	depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2485
2486config CALL_THUNKS
2487	def_bool n
2488	select CALL_PADDING
2489
2490config PREFIX_SYMBOLS
2491	def_bool y
2492	depends on CALL_PADDING && !CFI_CLANG
2493
2494menuconfig CPU_MITIGATIONS
2495	bool "Mitigations for CPU vulnerabilities"
2496	default y
2497	help
2498	  Say Y here to enable options which enable mitigations for hardware
2499	  vulnerabilities (usually related to speculative execution).
2500	  Mitigations can be disabled or restricted to SMT systems at runtime
2501	  via the "mitigations" kernel parameter.
2502
2503	  If you say N, all mitigations will be disabled.  This CANNOT be
2504	  overridden at runtime.
2505
2506	  Say 'Y', unless you really know what you are doing.
2507
2508if CPU_MITIGATIONS
2509
2510config MITIGATION_PAGE_TABLE_ISOLATION
2511	bool "Remove the kernel mapping in user mode"
2512	default y
2513	depends on (X86_64 || X86_PAE)
2514	help
2515	  This feature reduces the number of hardware side channels by
2516	  ensuring that the majority of kernel addresses are not mapped
2517	  into userspace.
2518
2519	  See Documentation/arch/x86/pti.rst for more details.
2520
2521config MITIGATION_RETPOLINE
2522	bool "Avoid speculative indirect branches in kernel"
2523	select OBJTOOL if HAVE_OBJTOOL
2524	default y
2525	help
2526	  Compile kernel with the retpoline compiler options to guard against
2527	  kernel-to-user data leaks by avoiding speculative indirect
2528	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2529	  support for full protection. The kernel may run slower.
2530
2531config MITIGATION_RETHUNK
2532	bool "Enable return-thunks"
2533	depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2534	select OBJTOOL if HAVE_OBJTOOL
2535	default y if X86_64
2536	help
2537	  Compile the kernel with the return-thunks compiler option to guard
2538	  against kernel-to-user data leaks by avoiding return speculation.
2539	  Requires a compiler with -mfunction-return=thunk-extern
2540	  support for full protection. The kernel may run slower.
2541
2542config MITIGATION_UNRET_ENTRY
2543	bool "Enable UNRET on kernel entry"
2544	depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2545	default y
2546	help
2547	  Compile the kernel with support for the retbleed=unret mitigation.
2548
2549config MITIGATION_CALL_DEPTH_TRACKING
2550	bool "Mitigate RSB underflow with call depth tracking"
2551	depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2552	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2553	select CALL_THUNKS
2554	default y
2555	help
2556	  Compile the kernel with call depth tracking to mitigate the Intel
2557	  SKL Return-Speculation-Buffer (RSB) underflow issue. The
2558	  mitigation is off by default and needs to be enabled on the
2559	  kernel command line via the retbleed=stuff option. For
2560	  non-affected systems the overhead of this option is marginal as
2561	  the call depth tracking is using run-time generated call thunks
2562	  in a compiler generated padding area and call patching. This
2563	  increases text size by ~5%. For non affected systems this space
2564	  is unused. On affected SKL systems this results in a significant
2565	  performance gain over the IBRS mitigation.
2566
2567config CALL_THUNKS_DEBUG
2568	bool "Enable call thunks and call depth tracking debugging"
2569	depends on MITIGATION_CALL_DEPTH_TRACKING
2570	select FUNCTION_ALIGNMENT_32B
2571	default n
2572	help
2573	  Enable call/ret counters for imbalance detection and build in
2574	  a noisy dmesg about callthunks generation and call patching for
2575	  trouble shooting. The debug prints need to be enabled on the
2576	  kernel command line with 'debug-callthunks'.
2577	  Only enable this when you are debugging call thunks as this
2578	  creates a noticeable runtime overhead. If unsure say N.
2579
2580config MITIGATION_IBPB_ENTRY
2581	bool "Enable IBPB on kernel entry"
2582	depends on CPU_SUP_AMD && X86_64
2583	default y
2584	help
2585	  Compile the kernel with support for the retbleed=ibpb mitigation.
2586
2587config MITIGATION_IBRS_ENTRY
2588	bool "Enable IBRS on kernel entry"
2589	depends on CPU_SUP_INTEL && X86_64
2590	default y
2591	help
2592	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2593	  This mitigates both spectre_v2 and retbleed at great cost to
2594	  performance.
2595
2596config MITIGATION_SRSO
2597	bool "Mitigate speculative RAS overflow on AMD"
2598	depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2599	default y
2600	help
2601	  Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2602
2603config MITIGATION_SLS
2604	bool "Mitigate Straight-Line-Speculation"
2605	depends on CC_HAS_SLS && X86_64
2606	select OBJTOOL if HAVE_OBJTOOL
2607	default n
2608	help
2609	  Compile the kernel with straight-line-speculation options to guard
2610	  against straight line speculation. The kernel image might be slightly
2611	  larger.
2612
2613config MITIGATION_GDS
2614	bool "Mitigate Gather Data Sampling"
2615	depends on CPU_SUP_INTEL
2616	default y
2617	help
2618	  Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
2619	  vulnerability which allows unprivileged speculative access to data
2620	  which was previously stored in vector registers. The attacker uses gather
2621	  instructions to infer the stale vector register data.
2622
2623config MITIGATION_RFDS
2624	bool "RFDS Mitigation"
2625	depends on CPU_SUP_INTEL
2626	default y
2627	help
2628	  Enable mitigation for Register File Data Sampling (RFDS) by default.
2629	  RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2630	  allows unprivileged speculative access to stale data previously
2631	  stored in floating point, vector and integer registers.
2632	  See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2633
2634config MITIGATION_SPECTRE_BHI
2635	bool "Mitigate Spectre-BHB (Branch History Injection)"
2636	depends on CPU_SUP_INTEL
2637	default y
2638	help
2639	  Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2640	  where the branch history buffer is poisoned to speculatively steer
2641	  indirect branches.
2642	  See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2643
2644config MITIGATION_MDS
2645	bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
2646	depends on CPU_SUP_INTEL
2647	default y
2648	help
2649	  Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
2650	  a hardware vulnerability which allows unprivileged speculative access
2651	  to data which is available in various CPU internal buffers.
2652	  See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
2653
2654config MITIGATION_TAA
2655	bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
2656	depends on CPU_SUP_INTEL
2657	default y
2658	help
2659	  Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
2660	  vulnerability that allows unprivileged speculative access to data
2661	  which is available in various CPU internal buffers by using
2662	  asynchronous aborts within an Intel TSX transactional region.
2663	  See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
2664
2665config MITIGATION_MMIO_STALE_DATA
2666	bool "Mitigate MMIO Stale Data hardware bug"
2667	depends on CPU_SUP_INTEL
2668	default y
2669	help
2670	  Enable mitigation for MMIO Stale Data hardware bugs.  Processor MMIO
2671	  Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
2672	  vulnerabilities that can expose data. The vulnerabilities require the
2673	  attacker to have access to MMIO.
2674	  See also
2675	  <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
2676
2677config MITIGATION_L1TF
2678	bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
2679	depends on CPU_SUP_INTEL
2680	default y
2681	help
2682	  Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
2683	  hardware vulnerability which allows unprivileged speculative access to data
2684	  available in the Level 1 Data Cache.
2685	  See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
2686
2687config MITIGATION_RETBLEED
2688	bool "Mitigate RETBleed hardware bug"
2689	depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
2690	default y
2691	help
2692	  Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
2693	  with Return Instructions) vulnerability.  RETBleed is a speculative
2694	  execution attack which takes advantage of microarchitectural behavior
2695	  in many modern microprocessors, similar to Spectre v2. An
2696	  unprivileged attacker can use these flaws to bypass conventional
2697	  memory security restrictions to gain read access to privileged memory
2698	  that would otherwise be inaccessible.
2699
2700config MITIGATION_SPECTRE_V1
2701	bool "Mitigate SPECTRE V1 hardware bug"
2702	default y
2703	help
2704	  Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
2705	  class of side channel attacks that takes advantage of speculative
2706	  execution that bypasses conditional branch instructions used for
2707	  memory access bounds check.
2708	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2709
2710config MITIGATION_SPECTRE_V2
2711	bool "Mitigate SPECTRE V2 hardware bug"
2712	default y
2713	help
2714	  Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
2715	  V2 is a class of side channel attacks that takes advantage of
2716	  indirect branch predictors inside the processor. In Spectre variant 2
2717	  attacks, the attacker can steer speculative indirect branches in the
2718	  victim to gadget code by poisoning the branch target buffer of a CPU
2719	  used for predicting indirect branch addresses.
2720	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2721
2722config MITIGATION_SRBDS
2723	bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
2724	depends on CPU_SUP_INTEL
2725	default y
2726	help
2727	  Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
2728	  SRBDS is a hardware vulnerability that allows Microarchitectural Data
2729	  Sampling (MDS) techniques to infer values returned from special
2730	  register accesses. An unprivileged user can extract values returned
2731	  from RDRAND and RDSEED executed on another core or sibling thread
2732	  using MDS techniques.
2733	  See also
2734	  <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
2735
2736config MITIGATION_SSB
2737	bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
2738	default y
2739	help
2740	  Enable mitigation for Speculative Store Bypass (SSB). SSB is a
2741	  hardware security vulnerability and its exploitation takes advantage
2742	  of speculative execution in a similar way to the Meltdown and Spectre
2743	  security vulnerabilities.
2744
2745endif
2746
2747config ARCH_HAS_ADD_PAGES
2748	def_bool y
2749	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2750
2751menu "Power management and ACPI options"
2752
2753config ARCH_HIBERNATION_HEADER
2754	def_bool y
2755	depends on HIBERNATION
2756
2757source "kernel/power/Kconfig"
2758
2759source "drivers/acpi/Kconfig"
2760
2761config X86_APM_BOOT
2762	def_bool y
2763	depends on APM
2764
2765menuconfig APM
2766	tristate "APM (Advanced Power Management) BIOS support"
2767	depends on X86_32 && PM_SLEEP
2768	help
2769	  APM is a BIOS specification for saving power using several different
2770	  techniques. This is mostly useful for battery powered laptops with
2771	  APM compliant BIOSes. If you say Y here, the system time will be
2772	  reset after a RESUME operation, the /proc/apm device will provide
2773	  battery status information, and user-space programs will receive
2774	  notification of APM "events" (e.g. battery status change).
2775
2776	  If you select "Y" here, you can disable actual use of the APM
2777	  BIOS by passing the "apm=off" option to the kernel at boot time.
2778
2779	  Note that the APM support is almost completely disabled for
2780	  machines with more than one CPU.
2781
2782	  In order to use APM, you will need supporting software. For location
2783	  and more information, read <file:Documentation/power/apm-acpi.rst>
2784	  and the Battery Powered Linux mini-HOWTO, available from
2785	  <http://www.tldp.org/docs.html#howto>.
2786
2787	  This driver does not spin down disk drives (see the hdparm(8)
2788	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2789	  VESA-compliant "green" monitors.
2790
2791	  This driver does not support the TI 4000M TravelMate and the ACER
2792	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2793	  desktop machines also don't have compliant BIOSes, and this driver
2794	  may cause those machines to panic during the boot phase.
2795
2796	  Generally, if you don't have a battery in your machine, there isn't
2797	  much point in using this driver and you should say N. If you get
2798	  random kernel OOPSes or reboots that don't seem to be related to
2799	  anything, try disabling/enabling this option (or disabling/enabling
2800	  APM in your BIOS).
2801
2802	  Some other things you should try when experiencing seemingly random,
2803	  "weird" problems:
2804
2805	  1) make sure that you have enough swap space and that it is
2806	  enabled.
2807	  2) pass the "idle=poll" option to the kernel
2808	  3) switch on floating point emulation in the kernel and pass
2809	  the "no387" option to the kernel
2810	  4) pass the "floppy=nodma" option to the kernel
2811	  5) pass the "mem=4M" option to the kernel (thereby disabling
2812	  all but the first 4 MB of RAM)
2813	  6) make sure that the CPU is not over clocked.
2814	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2815	  8) disable the cache from your BIOS settings
2816	  9) install a fan for the video card or exchange video RAM
2817	  10) install a better fan for the CPU
2818	  11) exchange RAM chips
2819	  12) exchange the motherboard.
2820
2821	  To compile this driver as a module, choose M here: the
2822	  module will be called apm.
2823
2824if APM
2825
2826config APM_IGNORE_USER_SUSPEND
2827	bool "Ignore USER SUSPEND"
2828	help
2829	  This option will ignore USER SUSPEND requests. On machines with a
2830	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2831	  series notebooks, it is necessary to say Y because of a BIOS bug.
2832
2833config APM_DO_ENABLE
2834	bool "Enable PM at boot time"
2835	help
2836	  Enable APM features at boot time. From page 36 of the APM BIOS
2837	  specification: "When disabled, the APM BIOS does not automatically
2838	  power manage devices, enter the Standby State, enter the Suspend
2839	  State, or take power saving steps in response to CPU Idle calls."
2840	  This driver will make CPU Idle calls when Linux is idle (unless this
2841	  feature is turned off -- see "Do CPU IDLE calls", below). This
2842	  should always save battery power, but more complicated APM features
2843	  will be dependent on your BIOS implementation. You may need to turn
2844	  this option off if your computer hangs at boot time when using APM
2845	  support, or if it beeps continuously instead of suspending. Turn
2846	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2847	  T400CDT. This is off by default since most machines do fine without
2848	  this feature.
2849
2850config APM_CPU_IDLE
2851	depends on CPU_IDLE
2852	bool "Make CPU Idle calls when idle"
2853	help
2854	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2855	  On some machines, this can activate improved power savings, such as
2856	  a slowed CPU clock rate, when the machine is idle. These idle calls
2857	  are made after the idle loop has run for some length of time (e.g.,
2858	  333 mS). On some machines, this will cause a hang at boot time or
2859	  whenever the CPU becomes idle. (On machines with more than one CPU,
2860	  this option does nothing.)
2861
2862config APM_DISPLAY_BLANK
2863	bool "Enable console blanking using APM"
2864	help
2865	  Enable console blanking using the APM. Some laptops can use this to
2866	  turn off the LCD backlight when the screen blanker of the Linux
2867	  virtual console blanks the screen. Note that this is only used by
2868	  the virtual console screen blanker, and won't turn off the backlight
2869	  when using the X Window system. This also doesn't have anything to
2870	  do with your VESA-compliant power-saving monitor. Further, this
2871	  option doesn't work for all laptops -- it might not turn off your
2872	  backlight at all, or it might print a lot of errors to the console,
2873	  especially if you are using gpm.
2874
2875config APM_ALLOW_INTS
2876	bool "Allow interrupts during APM BIOS calls"
2877	help
2878	  Normally we disable external interrupts while we are making calls to
2879	  the APM BIOS as a measure to lessen the effects of a badly behaving
2880	  BIOS implementation.  The BIOS should reenable interrupts if it
2881	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2882	  many of the newer IBM Thinkpads.  If you experience hangs when you
2883	  suspend, try setting this to Y.  Otherwise, say N.
2884
2885endif # APM
2886
2887source "drivers/cpufreq/Kconfig"
2888
2889source "drivers/cpuidle/Kconfig"
2890
2891source "drivers/idle/Kconfig"
2892
2893endmenu
2894
2895menu "Bus options (PCI etc.)"
2896
2897choice
2898	prompt "PCI access mode"
2899	depends on X86_32 && PCI
2900	default PCI_GOANY
2901	help
2902	  On PCI systems, the BIOS can be used to detect the PCI devices and
2903	  determine their configuration. However, some old PCI motherboards
2904	  have BIOS bugs and may crash if this is done. Also, some embedded
2905	  PCI-based systems don't have any BIOS at all. Linux can also try to
2906	  detect the PCI hardware directly without using the BIOS.
2907
2908	  With this option, you can specify how Linux should detect the
2909	  PCI devices. If you choose "BIOS", the BIOS will be used,
2910	  if you choose "Direct", the BIOS won't be used, and if you
2911	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2912	  If you choose "Any", the kernel will try MMCONFIG, then the
2913	  direct access method and falls back to the BIOS if that doesn't
2914	  work. If unsure, go with the default, which is "Any".
2915
2916config PCI_GOBIOS
2917	bool "BIOS"
2918
2919config PCI_GOMMCONFIG
2920	bool "MMConfig"
2921
2922config PCI_GODIRECT
2923	bool "Direct"
2924
2925config PCI_GOOLPC
2926	bool "OLPC XO-1"
2927	depends on OLPC
2928
2929config PCI_GOANY
2930	bool "Any"
2931
2932endchoice
2933
2934config PCI_BIOS
2935	def_bool y
2936	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2937
2938# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2939config PCI_DIRECT
2940	def_bool y
2941	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2942
2943config PCI_MMCONFIG
2944	bool "Support mmconfig PCI config space access" if X86_64
2945	default y
2946	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2947	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2948
2949config PCI_OLPC
2950	def_bool y
2951	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2952
2953config PCI_XEN
2954	def_bool y
2955	depends on PCI && XEN
2956
2957config MMCONF_FAM10H
2958	def_bool y
2959	depends on X86_64 && PCI_MMCONFIG && ACPI
2960
2961config PCI_CNB20LE_QUIRK
2962	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2963	depends on PCI
2964	help
2965	  Read the PCI windows out of the CNB20LE host bridge. This allows
2966	  PCI hotplug to work on systems with the CNB20LE chipset which do
2967	  not have ACPI.
2968
2969	  There's no public spec for this chipset, and this functionality
2970	  is known to be incomplete.
2971
2972	  You should say N unless you know you need this.
2973
2974config ISA_BUS
2975	bool "ISA bus support on modern systems" if EXPERT
2976	help
2977	  Expose ISA bus device drivers and options available for selection and
2978	  configuration. Enable this option if your target machine has an ISA
2979	  bus. ISA is an older system, displaced by PCI and newer bus
2980	  architectures -- if your target machine is modern, it probably does
2981	  not have an ISA bus.
2982
2983	  If unsure, say N.
2984
2985# x86_64 have no ISA slots, but can have ISA-style DMA.
2986config ISA_DMA_API
2987	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2988	default y
2989	help
2990	  Enables ISA-style DMA support for devices requiring such controllers.
2991	  If unsure, say Y.
2992
2993if X86_32
2994
2995config ISA
2996	bool "ISA support"
2997	help
2998	  Find out whether you have ISA slots on your motherboard.  ISA is the
2999	  name of a bus system, i.e. the way the CPU talks to the other stuff
3000	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
3001	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
3002	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
3003
3004config SCx200
3005	tristate "NatSemi SCx200 support"
3006	help
3007	  This provides basic support for National Semiconductor's
3008	  (now AMD's) Geode processors.  The driver probes for the
3009	  PCI-IDs of several on-chip devices, so its a good dependency
3010	  for other scx200_* drivers.
3011
3012	  If compiled as a module, the driver is named scx200.
3013
3014config SCx200HR_TIMER
3015	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
3016	depends on SCx200
3017	default y
3018	help
3019	  This driver provides a clocksource built upon the on-chip
3020	  27MHz high-resolution timer.  Its also a workaround for
3021	  NSC Geode SC-1100's buggy TSC, which loses time when the
3022	  processor goes idle (as is done by the scheduler).  The
3023	  other workaround is idle=poll boot option.
3024
3025config OLPC
3026	bool "One Laptop Per Child support"
3027	depends on !X86_PAE
3028	select GPIOLIB
3029	select OF
3030	select OF_PROMTREE
3031	select IRQ_DOMAIN
3032	select OLPC_EC
3033	help
3034	  Add support for detecting the unique features of the OLPC
3035	  XO hardware.
3036
3037config OLPC_XO1_PM
3038	bool "OLPC XO-1 Power Management"
3039	depends on OLPC && MFD_CS5535=y && PM_SLEEP
3040	help
3041	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
3042
3043config OLPC_XO1_RTC
3044	bool "OLPC XO-1 Real Time Clock"
3045	depends on OLPC_XO1_PM && RTC_DRV_CMOS
3046	help
3047	  Add support for the XO-1 real time clock, which can be used as a
3048	  programmable wakeup source.
3049
3050config OLPC_XO1_SCI
3051	bool "OLPC XO-1 SCI extras"
3052	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
3053	depends on INPUT=y
3054	select POWER_SUPPLY
3055	help
3056	  Add support for SCI-based features of the OLPC XO-1 laptop:
3057	   - EC-driven system wakeups
3058	   - Power button
3059	   - Ebook switch
3060	   - Lid switch
3061	   - AC adapter status updates
3062	   - Battery status updates
3063
3064config OLPC_XO15_SCI
3065	bool "OLPC XO-1.5 SCI extras"
3066	depends on OLPC && ACPI
3067	select POWER_SUPPLY
3068	help
3069	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
3070	   - EC-driven system wakeups
3071	   - AC adapter status updates
3072	   - Battery status updates
3073
3074config GEODE_COMMON
3075	bool
3076
3077config ALIX
3078	bool "PCEngines ALIX System Support (LED setup)"
3079	select GPIOLIB
3080	select GEODE_COMMON
3081	help
3082	  This option enables system support for the PCEngines ALIX.
3083	  At present this just sets up LEDs for GPIO control on
3084	  ALIX2/3/6 boards.  However, other system specific setup should
3085	  get added here.
3086
3087	  Note: You must still enable the drivers for GPIO and LED support
3088	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
3089
3090	  Note: You have to set alix.force=1 for boards with Award BIOS.
3091
3092config NET5501
3093	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
3094	select GPIOLIB
3095	select GEODE_COMMON
3096	help
3097	  This option enables system support for the Soekris Engineering net5501.
3098
3099config GEOS
3100	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
3101	select GPIOLIB
3102	select GEODE_COMMON
3103	depends on DMI
3104	help
3105	  This option enables system support for the Traverse Technologies GEOS.
3106
3107config TS5500
3108	bool "Technologic Systems TS-5500 platform support"
3109	depends on MELAN
3110	select CHECK_SIGNATURE
3111	select NEW_LEDS
3112	select LEDS_CLASS
3113	help
3114	  This option enables system support for the Technologic Systems TS-5500.
3115
3116endif # X86_32
3117
3118config AMD_NB
3119	def_bool y
3120	depends on CPU_SUP_AMD && PCI
3121
3122endmenu
3123
3124menu "Binary Emulations"
3125
3126config IA32_EMULATION
3127	bool "IA32 Emulation"
3128	depends on X86_64
3129	select ARCH_WANT_OLD_COMPAT_IPC
3130	select BINFMT_ELF
3131	select COMPAT_OLD_SIGACTION
3132	help
3133	  Include code to run legacy 32-bit programs under a
3134	  64-bit kernel. You should likely turn this on, unless you're
3135	  100% sure that you don't have any 32-bit programs left.
3136
3137config IA32_EMULATION_DEFAULT_DISABLED
3138	bool "IA32 emulation disabled by default"
3139	default n
3140	depends on IA32_EMULATION
3141	help
3142	  Make IA32 emulation disabled by default. This prevents loading 32-bit
3143	  processes and access to 32-bit syscalls. If unsure, leave it to its
3144	  default value.
3145
3146config X86_X32_ABI
3147	bool "x32 ABI for 64-bit mode"
3148	depends on X86_64
3149	# llvm-objcopy does not convert x86_64 .note.gnu.property or
3150	# compressed debug sections to x86_x32 properly:
3151	# https://github.com/ClangBuiltLinux/linux/issues/514
3152	# https://github.com/ClangBuiltLinux/linux/issues/1141
3153	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3154	help
3155	  Include code to run binaries for the x32 native 32-bit ABI
3156	  for 64-bit processors.  An x32 process gets access to the
3157	  full 64-bit register file and wide data path while leaving
3158	  pointers at 32 bits for smaller memory footprint.
3159
3160config COMPAT_32
3161	def_bool y
3162	depends on IA32_EMULATION || X86_32
3163	select HAVE_UID16
3164	select OLD_SIGSUSPEND3
3165
3166config COMPAT
3167	def_bool y
3168	depends on IA32_EMULATION || X86_X32_ABI
3169
3170config COMPAT_FOR_U64_ALIGNMENT
3171	def_bool y
3172	depends on COMPAT
3173
3174endmenu
3175
3176config HAVE_ATOMIC_IOMAP
3177	def_bool y
3178	depends on X86_32
3179
3180source "arch/x86/kvm/Kconfig"
3181
3182source "arch/x86/Kconfig.assembler"
3183