xref: /linux/arch/x86/Kconfig (revision c1fe867b5bf9c57ab7856486d342720e2b205eed)
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 HAVE_DEBUG_STACKOVERFLOW
18	select KMAP_LOCAL
19	select MODULES_USE_ELF_REL
20	select OLD_SIGACTION
21	select ARCH_SPLIT_ARG64
22
23config X86_64
24	def_bool y
25	depends on 64BIT
26	# Options that are inherently 64-bit kernel only:
27	select ARCH_HAS_GIGANTIC_PAGE
28	select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
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	select ACPI_MRRM if ACPI
40
41config FORCE_DYNAMIC_FTRACE
42	def_bool y
43	depends on X86_32
44	depends on FUNCTION_TRACER
45	select DYNAMIC_FTRACE
46	help
47	  We keep the static function tracing (!DYNAMIC_FTRACE) around
48	  in order to test the non static function tracing in the
49	  generic code, as other architectures still use it. But we
50	  only need to keep it around for x86_64. No need to keep it
51	  for x86_32. For x86_32, force DYNAMIC_FTRACE.
52#
53# Arch settings
54#
55# ( Note that options that are marked 'if X86_64' could in principle be
56#   ported to 32-bit as well. )
57#
58config X86
59	def_bool y
60	#
61	# Note: keep this list sorted alphabetically
62	#
63	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
64	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
65	select ACPI_HOTPLUG_CPU			if ACPI_PROCESSOR && HOTPLUG_CPU
66	select ARCH_32BIT_OFF_T			if X86_32
67	select ARCH_CLOCKSOURCE_INIT
68	select ARCH_CONFIGURES_CPU_MITIGATIONS
69	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
70	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
71	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
72	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
73	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
74	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
75	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
76	select ARCH_HAS_CPU_ATTACK_VECTORS	if CPU_MITIGATIONS
77	select ARCH_HAS_CACHE_LINE_SIZE
78	select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
79	select ARCH_HAS_CPU_FINALIZE_INIT
80	select ARCH_HAS_CPU_PASID		if IOMMU_SVA
81	select ARCH_HAS_CURRENT_STACK_POINTER
82	select ARCH_HAS_DEBUG_VIRTUAL
83	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
84	select ARCH_HAS_DEVMEM_IS_ALLOWED
85	select ARCH_HAS_DMA_OPS			if GART_IOMMU || XEN
86	select ARCH_HAS_EARLY_DEBUG		if KGDB
87	select ARCH_HAS_ELF_RANDOMIZE
88	select ARCH_HAS_EXECMEM_ROX		if X86_64 && STRICT_MODULE_RWX
89	select ARCH_HAS_FAST_MULTIPLIER
90	select ARCH_HAS_FORTIFY_SOURCE
91	select ARCH_HAS_GCOV_PROFILE_ALL
92	select ARCH_HAS_KCOV			if X86_64
93	select ARCH_HAS_KERNEL_FPU_SUPPORT
94	select ARCH_HAS_MEM_ENCRYPT
95	select ARCH_HAS_MEMBARRIER_SYNC_CORE
96	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
97	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
98	select ARCH_HAS_PMEM_API		if X86_64
99	select ARCH_HAS_PREEMPT_LAZY
100	select ARCH_HAS_PTDUMP
101	select ARCH_HAS_PTE_SPECIAL
102	select ARCH_HAS_HW_PTE_YOUNG
103	select ARCH_HAS_NONLEAF_PMD_YOUNG	if PGTABLE_LEVELS > 2
104	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
105	select ARCH_HAS_COPY_MC			if X86_64
106	select ARCH_HAS_SET_MEMORY
107	select ARCH_HAS_SET_DIRECT_MAP
108	select ARCH_HAS_STRICT_KERNEL_RWX
109	select ARCH_HAS_STRICT_MODULE_RWX
110	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
111	select ARCH_HAS_SYSCALL_WRAPPER
112	select ARCH_HAS_UBSAN
113	select ARCH_HAS_DEBUG_WX
114	select ARCH_HAS_ZONE_DMA_SET if EXPERT
115	select ARCH_HAVE_NMI_SAFE_CMPXCHG
116	select ARCH_HAVE_EXTRA_ELF_NOTES
117	select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
118	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
119	select ARCH_MIGHT_HAVE_PC_PARPORT
120	select ARCH_MIGHT_HAVE_PC_SERIO
121	select ARCH_STACKWALK
122	select ARCH_SUPPORTS_ACPI
123	select ARCH_SUPPORTS_ATOMIC_RMW
124	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
125	select ARCH_SUPPORTS_HUGETLBFS
126	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
127	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
128	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
129	select ARCH_SUPPORTS_CFI		if X86_64
130	select ARCH_USES_CFI_TRAPS		if X86_64 && CFI
131	select ARCH_SUPPORTS_LTO_CLANG
132	select ARCH_SUPPORTS_LTO_CLANG_THIN
133	select ARCH_SUPPORTS_RT
134	select ARCH_SUPPORTS_AUTOFDO_CLANG
135	select ARCH_SUPPORTS_PROPELLER_CLANG    if X86_64
136	select ARCH_USE_BUILTIN_BSWAP
137	select ARCH_USE_CMPXCHG_LOCKREF		if X86_CX8
138	select ARCH_USE_MEMTEST
139	select ARCH_USE_QUEUED_RWLOCKS
140	select ARCH_USE_QUEUED_SPINLOCKS
141	select ARCH_USE_SYM_ANNOTATIONS
142	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
143	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
144	select ARCH_WANTS_CLOCKSOURCE_READ_INLINE	if X86_64
145	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
146	select ARCH_WANTS_NO_INSTR
147	select ARCH_WANT_GENERAL_HUGETLB
148	select ARCH_WANT_HUGE_PMD_SHARE		if X86_64
149	select ARCH_WANT_LD_ORPHAN_WARN
150	select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP	if X86_64
151	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP	if X86_64
152	select ARCH_WANT_HUGETLB_VMEMMAP_PREINIT if X86_64
153	select ARCH_WANTS_THP_SWAP		if X86_64
154	select ARCH_HAS_PARANOID_L1D_FLUSH
155	select ARCH_WANT_IRQS_OFF_ACTIVATE_MM
156	select BUILDTIME_TABLE_SORT
157	select CLKEVT_I8253
158	select CLOCKSOURCE_WATCHDOG
159	# Word-size accesses may read uninitialized data past the trailing \0
160	# in strings and cause false KMSAN reports.
161	select DCACHE_WORD_ACCESS		if !KMSAN
162	select DYNAMIC_SIGFRAME
163	select EDAC_ATOMIC_SCRUB
164	select EDAC_SUPPORT
165	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
166	select GENERIC_CLOCKEVENTS_BROADCAST_IDLE	if GENERIC_CLOCKEVENTS_BROADCAST
167	select GENERIC_CLOCKEVENTS_COUPLED_INLINE	if X86_64
168	select GENERIC_CLOCKEVENTS_MIN_ADJUST
169	select GENERIC_CMOS_UPDATE
170	select GENERIC_CPU_AUTOPROBE
171	select GENERIC_CPU_DEVICES
172	select GENERIC_CPU_VULNERABILITIES
173	select GENERIC_EARLY_IOREMAP
174	select GENERIC_ENTRY
175	select GENERIC_IOMAP
176	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
177	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
178	select GENERIC_IRQ_MIGRATION		if SMP
179	select GENERIC_IRQ_PROBE
180	select GENERIC_IRQ_RESERVATION_MODE
181	select GENERIC_IRQ_SHOW
182	select GENERIC_PENDING_IRQ		if SMP
183	select GENERIC_SMP_IDLE_THREAD
184	select GENERIC_TIME_VSYSCALL
185	select GENERIC_GETTIMEOFDAY
186	select GENERIC_VDSO_OVERFLOW_PROTECT
187	select GUP_GET_PXX_LOW_HIGH		if X86_PAE
188	select HARDIRQS_SW_RESEND
189	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
190	select HAS_IOPORT
191	select HAVE_ACPI_APEI			if ACPI
192	select HAVE_ACPI_APEI_NMI		if ACPI
193	select HAVE_ALIGNED_STRUCT_PAGE
194	select HAVE_ARCH_AUDITSYSCALL
195	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
196	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
197	select HAVE_ARCH_JUMP_LABEL
198	select HAVE_ARCH_JUMP_LABEL_RELATIVE
199	select HAVE_ARCH_KASAN			if X86_64
200	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
201	select HAVE_ARCH_KFENCE
202	select HAVE_ARCH_KMSAN			if X86_64
203	select HAVE_ARCH_KGDB
204	select HAVE_ARCH_KSTACK_ERASE
205	select HAVE_ARCH_MMAP_RND_BITS		if MMU
206	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
207	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
208	select HAVE_ARCH_PREL32_RELOCATIONS
209	select HAVE_ARCH_SECCOMP_FILTER
210	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
211	select HAVE_ARCH_TRACEHOOK
212	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
213	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
214	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
215	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
216	select HAVE_ARCH_VMAP_STACK		if X86_64
217	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
218	select HAVE_ARCH_WITHIN_STACK_FRAMES
219	select HAVE_ASM_MODVERSIONS
220	select HAVE_CMPXCHG_DOUBLE
221	select HAVE_CMPXCHG_LOCAL
222	select HAVE_CONTEXT_TRACKING_USER		if X86_64
223	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
224	select HAVE_C_RECORDMCOUNT
225	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
226	select HAVE_OBJTOOL_NOP_MCOUNT		if HAVE_OBJTOOL_MCOUNT
227	select HAVE_BUILDTIME_MCOUNT_SORT
228	select HAVE_DEBUG_KMEMLEAK
229	select HAVE_DMA_CONTIGUOUS
230	select HAVE_DYNAMIC_FTRACE
231	select HAVE_DYNAMIC_FTRACE_WITH_REGS
232	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
233	select HAVE_FTRACE_REGS_HAVING_PT_REGS	if X86_64
234	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
235	select HAVE_DYNAMIC_FTRACE_WITH_JMP	if X86_64
236	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
237	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
238	select HAVE_EBPF_JIT
239	select HAVE_EFFICIENT_UNALIGNED_ACCESS
240	select HAVE_EISA			if X86_32
241	select HAVE_EXIT_THREAD
242	select HAVE_GENERIC_TIF_BITS
243	select HAVE_GUP_FAST
244	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
245	select HAVE_FTRACE_GRAPH_FUNC		if HAVE_FUNCTION_GRAPH_TRACER
246	select HAVE_FUNCTION_GRAPH_FREGS	if HAVE_FUNCTION_GRAPH_TRACER
247	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
248	select HAVE_FUNCTION_TRACER
249	select HAVE_GCC_PLUGINS
250	select HAVE_HW_BREAKPOINT
251	select HAVE_IOREMAP_PROT
252	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
253	select HAVE_IRQ_TIME_ACCOUNTING
254	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
255	select HAVE_KERNEL_BZIP2
256	select HAVE_KERNEL_GZIP
257	select HAVE_KERNEL_LZ4
258	select HAVE_KERNEL_LZMA
259	select HAVE_KERNEL_LZO
260	select HAVE_KERNEL_XZ
261	select HAVE_KERNEL_ZSTD
262	select HAVE_KPROBES
263	select HAVE_KPROBES_ON_FTRACE
264	select HAVE_FUNCTION_ERROR_INJECTION
265	select HAVE_KRETPROBES
266	select HAVE_RETHOOK
267	select HAVE_KLP_BUILD			if X86_64
268	select HAVE_LIVEPATCH			if X86_64
269	select HAVE_MIXED_BREAKPOINTS_REGS
270	select HAVE_MOD_ARCH_SPECIFIC
271	select HAVE_MOVE_PMD
272	select HAVE_MOVE_PUD
273	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
274	select HAVE_NMI
275	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
276	select HAVE_OBJTOOL			if X86_64
277	select HAVE_OPTPROBES
278	select HAVE_PAGE_SIZE_4KB
279	select HAVE_PCSPKR_PLATFORM
280	select HAVE_PERF_EVENTS
281	select HAVE_PERF_EVENTS_NMI
282	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
283	select HAVE_PCI
284	select HAVE_PERF_REGS
285	select HAVE_PERF_USER_STACK_DUMP
286	select ASYNC_KERNEL_PGTABLE_FREE	if IOMMU_SVA
287	select MMU_GATHER_RCU_TABLE_FREE
288	select MMU_GATHER_MERGE_VMAS
289	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
290	select HAVE_REGS_AND_STACK_ACCESS_API
291	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
292	select HAVE_FUNCTION_ARG_ACCESS_API
293	select HAVE_SETUP_PER_CPU_AREA
294	select HAVE_SOFTIRQ_ON_OWN_STACK
295	select HAVE_STACKPROTECTOR
296	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
297	select HAVE_STATIC_CALL
298	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
299	select HAVE_PREEMPT_DYNAMIC_CALL
300	select HAVE_RSEQ
301	select HAVE_RUST			if X86_64
302	select HAVE_SYSCALL_TRACEPOINTS
303	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
304	select HAVE_UNSTABLE_SCHED_CLOCK
305	select HAVE_UNWIND_USER_FP		if X86_64
306	select HAVE_USER_RETURN_NOTIFIER
307	select HAVE_GENERIC_VDSO
308	select VDSO_GETRANDOM			if X86_64
309	select HOTPLUG_PARALLEL			if SMP && X86_64
310	select HOTPLUG_SMT			if SMP
311	select HOTPLUG_SPLIT_STARTUP		if SMP && X86_32
312	select IRQ_FORCED_THREADING
313	select LOCK_MM_AND_FIND_VMA
314	select NEED_PER_CPU_EMBED_FIRST_CHUNK
315	select NEED_PER_CPU_PAGE_FIRST_CHUNK
316	select NEED_SG_DMA_LENGTH
317	select NUMA_MEMBLKS			if NUMA
318	select PCI_DOMAINS			if PCI
319	select PCI_LOCKLESS_CONFIG		if PCI
320	select PERF_EVENTS
321	select RTC_LIB
322	select RTC_MC146818_LIB
323	select SPARSE_IRQ
324	select SYSCTL_EXCEPTION_TRACE
325	select THREAD_INFO_IN_TASK
326	select TRACE_IRQFLAGS_SUPPORT
327	select TRACE_IRQFLAGS_NMI_SUPPORT
328	select USER_STACKTRACE_SUPPORT
329	select HAVE_ARCH_KCSAN			if X86_64
330	select PROC_PID_ARCH_STATUS		if PROC_FS
331	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
332	select FUNCTION_ALIGNMENT_16B		if X86_64 || X86_ALIGNMENT_16
333	select FUNCTION_ALIGNMENT_4B
334	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
335	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
336	select ARCH_SUPPORTS_SCHED_SMT		if SMP
337	select SCHED_SMT			if SMP
338	select ARCH_SUPPORTS_SCHED_CLUSTER	if SMP
339	select ARCH_SUPPORTS_SCHED_MC		if SMP
340	select HAVE_SINGLE_FTRACE_DIRECT_OPS	if X86_64 && DYNAMIC_FTRACE_WITH_DIRECT_CALLS
341
342config INSTRUCTION_DECODER
343	def_bool y
344	depends on KPROBES || PERF_EVENTS || UPROBES
345
346config OUTPUT_FORMAT
347	string
348	default "elf32-i386" if X86_32
349	default "elf64-x86-64" if X86_64
350
351config LOCKDEP_SUPPORT
352	def_bool y
353
354config STACKTRACE_SUPPORT
355	def_bool y
356
357config MMU
358	def_bool y
359
360config ARCH_MMAP_RND_BITS_MIN
361	default 28 if 64BIT
362	default 8
363
364config ARCH_MMAP_RND_BITS_MAX
365	default 32 if 64BIT
366	default 16
367
368config ARCH_MMAP_RND_COMPAT_BITS_MIN
369	default 8
370
371config ARCH_MMAP_RND_COMPAT_BITS_MAX
372	default 16
373
374config SBUS
375	bool
376
377config GENERIC_ISA_DMA
378	def_bool y
379	depends on ISA_DMA_API
380
381config GENERIC_CSUM
382	bool
383	default y if KMSAN || KASAN
384
385config GENERIC_BUG
386	def_bool y
387	depends on BUG
388	select GENERIC_BUG_RELATIVE_POINTERS
389
390config GENERIC_BUG_RELATIVE_POINTERS
391	bool
392
393config ARCH_MAY_HAVE_PC_FDC
394	def_bool y
395	depends on ISA_DMA_API
396
397config GENERIC_CALIBRATE_DELAY
398	def_bool y
399
400config ARCH_HAS_CPU_RELAX
401	def_bool y
402
403config ARCH_HIBERNATION_POSSIBLE
404	def_bool y
405
406config ARCH_SUSPEND_POSSIBLE
407	def_bool y
408
409config AUDIT_ARCH
410	def_bool y if X86_64
411
412config KASAN_SHADOW_OFFSET
413	hex
414	depends on KASAN
415	default 0xdffffc0000000000
416
417config HAVE_INTEL_TXT
418	def_bool y
419	depends on INTEL_IOMMU && ACPI
420
421config ARCH_SUPPORTS_UPROBES
422	def_bool y
423
424config FIX_EARLYCON_MEM
425	def_bool y
426
427config DYNAMIC_PHYSICAL_MASK
428	bool
429
430config PGTABLE_LEVELS
431	int
432	default 5 if X86_64
433	default 3 if X86_PAE
434	default 2
435
436menu "Processor type and features"
437
438config SMP
439	bool "Symmetric multi-processing support"
440	help
441	  This enables support for systems with more than one CPU. If you have
442	  a system with only one CPU, say N. If you have a system with more
443	  than one CPU, say Y.
444
445	  If you say N here, the kernel will run on uni- and multiprocessor
446	  machines, but will use only one CPU of a multiprocessor machine. If
447	  you say Y here, the kernel will run on many, but not all,
448	  uniprocessor machines. On a uniprocessor machine, the kernel
449	  will run faster if you say N here.
450
451	  Note that if you say Y here and choose architecture "586" or
452	  "Pentium" under "Processor family", the kernel will not work on 486
453	  architectures. Similarly, multiprocessor kernels for the "PPro"
454	  architecture may not work on all Pentium based boards.
455
456	  People using multiprocessor machines who say Y here should also say
457	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
458	  Management" code will be disabled if you say Y here.
459
460	  See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
461	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
462	  <http://www.tldp.org/docs.html#howto>.
463
464	  If you don't know what to do here, say N.
465
466config X86_X2APIC
467	bool "x2APIC interrupt controller architecture support"
468	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
469	default y
470	help
471	  x2APIC is an interrupt controller architecture, a component of which
472	  (the local APIC) is present in the CPU. It allows faster access to
473	  the local APIC and supports a larger number of CPUs in the system
474	  than the predecessors.
475
476	  x2APIC was introduced in Intel CPUs around 2008 and in AMD EPYC CPUs
477	  in 2019, but it can be disabled by the BIOS. It is also frequently
478	  emulated in virtual machines, even when the host CPU does not support
479	  it. Support in the CPU can be checked by executing
480		grep x2apic /proc/cpuinfo
481
482	  If this configuration option is disabled, the kernel will boot with
483	  very reduced functionality and performance on some platforms that
484	  have x2APIC enabled. On the other hand, on hardware that does not
485	  support x2APIC, a kernel with this option enabled will just fallback
486	  to older APIC implementations.
487
488	  If in doubt, say Y.
489
490config AMD_SECURE_AVIC
491	bool "AMD Secure AVIC"
492	depends on AMD_MEM_ENCRYPT && X86_X2APIC
493	help
494	  Enable this to get AMD Secure AVIC support on guests that have this feature.
495
496	  AMD Secure AVIC provides hardware acceleration for performance sensitive
497	  APIC accesses and support for managing guest owned APIC state for SEV-SNP
498	  guests. Secure AVIC does not support xAPIC mode. It has functional
499	  dependency on x2apic being enabled in the guest.
500
501	  If you don't know what to do here, say N.
502
503config X86_POSTED_MSI
504	bool "Enable MSI and MSI-x delivery by posted interrupts"
505	depends on X86_64 && IRQ_REMAP
506	help
507	  This enables MSIs that are under interrupt remapping to be delivered as
508	  posted interrupts to the host kernel. Interrupt throughput can
509	  potentially be improved by coalescing CPU notifications during high
510	  frequency bursts.
511
512	  If you don't know what to do here, say N.
513
514config X86_MPPARSE
515	bool "Enable MPS table" if ACPI
516	default y
517	depends on X86_LOCAL_APIC
518	help
519	  For old smp systems that do not have proper acpi support. Newer systems
520	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
521
522config X86_CPU_RESCTRL
523	bool "x86 CPU resource control support"
524	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
525	depends on MISC_FILESYSTEMS
526	select ARCH_HAS_CPU_RESCTRL
527	select RESCTRL_FS
528	select RESCTRL_FS_PSEUDO_LOCK
529	help
530	  Enable x86 CPU resource control support.
531
532	  Provide support for the allocation and monitoring of system resources
533	  usage by the CPU.
534
535	  Intel calls this Intel Resource Director Technology
536	  (Intel(R) RDT). More information about RDT can be found in the
537	  Intel x86 Architecture Software Developer Manual.
538
539	  AMD calls this AMD Platform Quality of Service (AMD QoS).
540	  More information about AMD QoS can be found in the AMD64 Technology
541	  Platform Quality of Service Extensions manual.
542
543	  Say N if unsure.
544
545config X86_CPU_RESCTRL_INTEL_AET
546	bool "Intel Application Energy Telemetry"
547	depends on X86_64 && X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y
548	help
549	  Enable per-RMID telemetry events in resctrl.
550
551	  Intel feature that collects per-RMID execution data
552	  about energy consumption, measure of frequency independent
553	  activity and other performance metrics. Data is aggregated
554	  per package.
555
556	  Say N if unsure.
557
558config X86_FRED
559	bool "Flexible Return and Event Delivery"
560	depends on X86_64
561	help
562	  When enabled, try to use Flexible Return and Event Delivery
563	  instead of the legacy SYSCALL/SYSENTER/IDT architecture for
564	  ring transitions and exception/interrupt handling if the
565	  system supports it.
566
567config X86_EXTENDED_PLATFORM
568	bool "Support for extended (non-PC) x86 platforms"
569	default y
570	help
571	  If you disable this option then the kernel will only support
572	  standard PC platforms. (which covers the vast majority of
573	  systems out there.)
574
575	  If you enable this option then you'll be able to select support
576	  for the following non-PC x86 platforms, depending on the value of
577	  CONFIG_64BIT.
578
579	  32-bit platforms (CONFIG_64BIT=n):
580		Goldfish (mostly Android emulator)
581		Intel CE media processor (CE4100) SoC
582		Intel Quark
583		RDC R-321x SoC
584
585	  64-bit platforms (CONFIG_64BIT=y):
586		Numascale NumaChip
587		ScaleMP vSMP
588		SGI Ultraviolet
589		Merrifield/Moorefield MID devices
590		Goldfish (mostly Android emulator)
591
592	  If you have one of these systems, or if you want to build a
593	  generic distribution kernel, say Y here - otherwise say N.
594
595# This is an alphabetically sorted list of 64 bit extended platforms
596# Please maintain the alphabetic order if and when there are additions
597config X86_NUMACHIP
598	bool "Numascale NumaChip"
599	depends on X86_64
600	depends on X86_EXTENDED_PLATFORM
601	depends on NUMA
602	depends on SMP
603	depends on X86_X2APIC
604	depends on PCI_MMCONFIG
605	help
606	  Adds support for Numascale NumaChip large-SMP systems. Needed to
607	  enable more than ~168 cores.
608	  If you don't have one of these, you should say N here.
609
610config X86_VSMP
611	bool "ScaleMP vSMP"
612	select HYPERVISOR_GUEST
613	select PARAVIRT
614	depends on X86_64 && PCI
615	depends on X86_EXTENDED_PLATFORM
616	depends on SMP
617	help
618	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
619	  supposed to run on these EM64T-based machines.  Only choose this option
620	  if you have one of these machines.
621
622config X86_UV
623	bool "SGI Ultraviolet"
624	depends on X86_64
625	depends on X86_EXTENDED_PLATFORM
626	depends on NUMA
627	depends on EFI
628	depends on KEXEC_CORE
629	depends on X86_X2APIC
630	depends on PCI
631	help
632	  This option is needed in order to support SGI Ultraviolet systems.
633	  If you don't have one of these, you should say N here.
634
635config X86_INTEL_MID
636	bool "Intel Z34xx/Z35xx MID platform support"
637	depends on X86_EXTENDED_PLATFORM
638	depends on X86_PLATFORM_DEVICES
639	depends on PCI
640	depends on X86_64 || (EXPERT && PCI_GOANY)
641	depends on X86_IO_APIC
642	select I2C
643	select DW_APB_TIMER
644	select INTEL_SCU_PCI
645	help
646	  Select to build a kernel capable of supporting 64-bit Intel MID
647	  (Mobile Internet Device) platform systems which do not have
648	  the PCI legacy interfaces.
649
650	  The only supported devices are the 22nm Merrified (Z34xx)
651	  and Moorefield (Z35xx) SoC used in the Intel Edison board and
652	  a small number of Android devices such as the Asus Zenfone 2,
653	  Asus FonePad 8 and Dell Venue 7.
654
655	  If you are building for a PC class system or non-MID tablet
656	  SoCs like Bay Trail (Z36xx/Z37xx), say N here.
657
658	  Intel MID platforms are based on an Intel processor and chipset which
659	  consume less power than most of the x86 derivatives.
660
661config X86_GOLDFISH
662	bool "Goldfish (Virtual Platform)"
663	depends on X86_EXTENDED_PLATFORM
664	help
665	  Enable support for the Goldfish virtual platform used primarily
666	  for Android development. Unless you are building for the Android
667	  Goldfish emulator say N here.
668
669# Following is an alphabetically sorted list of 32 bit extended platforms
670# Please maintain the alphabetic order if and when there are additions
671
672config X86_INTEL_CE
673	bool "CE4100 TV platform"
674	depends on PCI
675	depends on PCI_GODIRECT
676	depends on X86_IO_APIC
677	depends on X86_32
678	depends on X86_EXTENDED_PLATFORM
679	select X86_REBOOTFIXUPS
680	select OF
681	select OF_EARLY_FLATTREE
682	help
683	  Select for the Intel CE media processor (CE4100) SOC.
684	  This option compiles in support for the CE4100 SOC for settop
685	  boxes and media devices.
686
687config X86_INTEL_QUARK
688	bool "Intel Quark platform support"
689	depends on X86_32
690	depends on X86_EXTENDED_PLATFORM
691	depends on X86_PLATFORM_DEVICES
692	depends on X86_TSC
693	depends on PCI
694	depends on PCI_GOANY
695	depends on X86_IO_APIC
696	select IOSF_MBI
697	select INTEL_IMR
698	select COMMON_CLK
699	help
700	  Select to include support for Quark X1000 SoC.
701	  Say Y here if you have a Quark based system such as the Arduino
702	  compatible Intel Galileo.
703
704config X86_RDC321X
705	bool "RDC R-321x SoC"
706	depends on X86_32
707	depends on X86_EXTENDED_PLATFORM
708	select M486
709	select X86_REBOOTFIXUPS
710	help
711	  This option is needed for RDC R-321x system-on-chip, also known
712	  as R-8610-(G).
713	  If you don't have one of these chips, you should say N here.
714
715config X86_INTEL_LPSS
716	bool "Intel Low Power Subsystem Support"
717	depends on X86 && ACPI && PCI
718	select COMMON_CLK
719	select PINCTRL
720	select IOSF_MBI
721	help
722	  Select to build support for Intel Low Power Subsystem such as
723	  found on Intel Lynxpoint PCH. Selecting this option enables
724	  things like clock tree (common clock framework) and pincontrol
725	  which are needed by the LPSS peripheral drivers.
726
727config X86_AMD_PLATFORM_DEVICE
728	bool "AMD ACPI2Platform devices support"
729	depends on ACPI
730	select COMMON_CLK
731	select PINCTRL
732	help
733	  Select to interpret AMD specific ACPI device to platform device
734	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
735	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
736	  implemented under PINCTRL subsystem.
737
738config IOSF_MBI
739	tristate "Intel SoC IOSF Sideband support for SoC platforms"
740	depends on PCI
741	help
742	  This option enables sideband register access support for Intel SoC
743	  platforms. On these platforms the IOSF sideband is used in lieu of
744	  MSR's for some register accesses, mostly but not limited to thermal
745	  and power. Drivers may query the availability of this device to
746	  determine if they need the sideband in order to work on these
747	  platforms. The sideband is available on the following SoC products.
748	  This list is not meant to be exclusive.
749	   - BayTrail
750	   - Braswell
751	   - Quark
752
753	  You should say Y if you are running a kernel on one of these SoC's.
754
755config IOSF_MBI_DEBUG
756	bool "Enable IOSF sideband access through debugfs"
757	depends on IOSF_MBI && DEBUG_FS
758	help
759	  Select this option to expose the IOSF sideband access registers (MCR,
760	  MDR, MCRX) through debugfs to write and read register information from
761	  different units on the SoC. This is most useful for obtaining device
762	  state information for debug and analysis. As this is a general access
763	  mechanism, users of this option would have specific knowledge of the
764	  device they want to access.
765
766	  If you don't require the option or are in doubt, say N.
767
768config X86_SUPPORTS_MEMORY_FAILURE
769	def_bool y
770	# MCE code calls memory_failure():
771	depends on X86_MCE
772	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
773	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
774	depends on X86_64 || !SPARSEMEM
775	select ARCH_SUPPORTS_MEMORY_FAILURE
776
777config X86_32_IRIS
778	tristate "Eurobraille/Iris poweroff module"
779	depends on X86_32
780	help
781	  The Iris machines from EuroBraille do not have APM or ACPI support
782	  to shut themselves down properly.  A special I/O sequence is
783	  needed to do so, which is what this module does at
784	  kernel shutdown.
785
786	  This is only for Iris machines from EuroBraille.
787
788	  If unused, say N.
789
790config SCHED_OMIT_FRAME_POINTER
791	def_bool y
792	prompt "Single-depth WCHAN output"
793	depends on X86
794	help
795	  Calculate simpler /proc/<PID>/wchan values. If this option
796	  is disabled then wchan values will recurse back to the
797	  caller function. This provides more accurate wchan values,
798	  at the expense of slightly more scheduling overhead.
799
800	  If in doubt, say "Y".
801
802menuconfig HYPERVISOR_GUEST
803	bool "Linux guest support"
804	help
805	  Say Y here to enable options for running Linux under various hyper-
806	  visors. This option enables basic hypervisor detection and platform
807	  setup.
808
809	  If you say N, all options in this submenu will be skipped and
810	  disabled, and Linux guest support won't be built in.
811
812if HYPERVISOR_GUEST
813
814config PARAVIRT
815	bool "Enable paravirtualization code"
816	depends on HAVE_STATIC_CALL
817	select HAVE_PV_STEAL_CLOCK_GEN
818	help
819	  This changes the kernel so it can modify itself when it is run
820	  under a hypervisor, potentially improving performance significantly
821	  over full virtualization.  However, when run without a hypervisor
822	  the kernel is theoretically slower and slightly larger.
823
824config PARAVIRT_XXL
825	bool
826	depends on X86_64
827	select ARCH_HAS_LAZY_MMU_MODE
828
829config PARAVIRT_SPINLOCKS
830	bool "Paravirtualization layer for spinlocks"
831	depends on PARAVIRT && SMP
832	help
833	  Paravirtualized spinlocks allow a pvops backend to replace the
834	  spinlock implementation with something virtualization-friendly
835	  (for example, block the virtual CPU rather than spinning).
836
837	  It has a minimal impact on native kernels and gives a nice performance
838	  benefit on paravirtualized KVM / Xen kernels.
839
840	  If you are unsure how to answer this question, answer Y.
841
842config X86_HV_CALLBACK_VECTOR
843	def_bool n
844
845source "arch/x86/xen/Kconfig"
846
847config KVM_GUEST
848	bool "KVM Guest support (including kvmclock)"
849	depends on PARAVIRT
850	select PARAVIRT_CLOCK
851	select ARCH_CPUIDLE_HALTPOLL
852	select X86_HV_CALLBACK_VECTOR
853	default y
854	help
855	  This option enables various optimizations for running under the KVM
856	  hypervisor. It includes a paravirtualized clock, so that instead
857	  of relying on a PIT (or probably other) emulation by the
858	  underlying device model, the host provides the guest with
859	  timing infrastructure such as time of day, and system time
860
861config ARCH_CPUIDLE_HALTPOLL
862	def_bool n
863	prompt "Disable host haltpoll when loading haltpoll driver"
864	help
865	  If virtualized under KVM, disable host haltpoll.
866
867config PVH
868	bool "Support for running PVH guests"
869	help
870	  This option enables the PVH entry point for guest virtual machines
871	  as specified in the x86/HVM direct boot ABI.
872
873config PARAVIRT_TIME_ACCOUNTING
874	bool "Paravirtual steal time accounting"
875	depends on PARAVIRT
876	help
877	  Select this option to enable fine granularity task steal time
878	  accounting. Time spent executing other tasks in parallel with
879	  the current vCPU is discounted from the vCPU power. To account for
880	  that, there can be a small performance impact.
881
882	  If in doubt, say N here.
883
884config PARAVIRT_CLOCK
885	bool
886
887config JAILHOUSE_GUEST
888	bool "Jailhouse non-root cell support"
889	depends on X86_64 && PCI
890	select X86_PM_TIMER
891	help
892	  This option allows to run Linux as guest in a Jailhouse non-root
893	  cell. You can leave this option disabled if you only want to start
894	  Jailhouse and run Linux afterwards in the root cell.
895
896config ACRN_GUEST
897	bool "ACRN Guest support"
898	depends on X86_64
899	select X86_HV_CALLBACK_VECTOR
900	help
901	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
902	  a flexible, lightweight reference open-source hypervisor, built with
903	  real-time and safety-criticality in mind. It is built for embedded
904	  IOT with small footprint and real-time features. More details can be
905	  found in https://projectacrn.org/.
906
907config BHYVE_GUEST
908	bool "Bhyve (BSD Hypervisor) Guest support"
909	depends on X86_64
910	help
911	  This option allows to run Linux to recognise when it is running as a
912	  guest in the Bhyve hypervisor, and to support more than 255 vCPUs when
913	  when doing so. More details about Bhyve can be found at https://bhyve.org
914	  and https://wiki.freebsd.org/bhyve/.
915
916config INTEL_TDX_GUEST
917	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
918	depends on X86_64 && CPU_SUP_INTEL
919	depends on X86_X2APIC
920	depends on EFI_STUB
921	depends on PARAVIRT
922	select ARCH_HAS_CC_PLATFORM
923	select X86_MEM_ENCRYPT
924	select X86_MCE
925	select UNACCEPTED_MEMORY
926	help
927	  Support running as a guest under Intel TDX.  Without this support,
928	  the guest kernel can not boot or run under TDX.
929	  TDX includes memory encryption and integrity capabilities
930	  which protect the confidentiality and integrity of guest
931	  memory contents and CPU state. TDX guests are protected from
932	  some attacks from the VMM.
933
934endif # HYPERVISOR_GUEST
935
936source "arch/x86/Kconfig.cpu"
937
938config HPET_TIMER
939	def_bool X86_64
940	prompt "HPET Timer Support" if X86_32
941	help
942	  Use the IA-PC HPET (High Precision Event Timer) to manage
943	  time in preference to the PIT and RTC, if a HPET is
944	  present.
945	  HPET is the next generation timer replacing legacy 8254s.
946	  The HPET provides a stable time base on SMP
947	  systems, unlike the TSC, but it is more expensive to access,
948	  as it is off-chip.  The interface used is documented
949	  in the HPET spec, revision 1.
950
951	  You can safely choose Y here.  However, HPET will only be
952	  activated if the platform and the BIOS support this feature.
953	  Otherwise the 8254 will be used for timing services.
954
955	  Choose N to continue using the legacy 8254 timer.
956
957config HPET_EMULATE_RTC
958	def_bool y
959	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
960
961# Mark as expert because too many people got it wrong.
962# The code disables itself when not needed.
963config DMI
964	default y
965	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
966	bool "Enable DMI scanning" if EXPERT
967	help
968	  Enabled scanning of DMI to identify machine quirks. Say Y
969	  here unless you have verified that your setup is not
970	  affected by entries in the DMI blacklist. Required by PNP
971	  BIOS code.
972
973config GART_IOMMU
974	bool "Old AMD GART IOMMU support"
975	select IOMMU_HELPER
976	select SWIOTLB
977	depends on X86_64 && PCI && AMD_NB
978	help
979	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
980	  GART based hardware IOMMUs.
981
982	  The GART supports full DMA access for devices with 32-bit access
983	  limitations, on systems with more than 3 GB. This is usually needed
984	  for USB, sound, many IDE/SATA chipsets and some other devices.
985
986	  Newer systems typically have a modern AMD IOMMU, supported via
987	  the CONFIG_AMD_IOMMU=y config option.
988
989	  In normal configurations this driver is only active when needed:
990	  there's more than 3 GB of memory and the system contains a
991	  32-bit limited device.
992
993	  If unsure, say Y.
994
995config BOOT_VESA_SUPPORT
996	bool
997	help
998	  If true, at least one selected framebuffer driver can take advantage
999	  of VESA video modes set at an early boot stage via the vga= parameter.
1000
1001config MAXSMP
1002	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
1003	depends on X86_64 && SMP && DEBUG_KERNEL
1004	select CPUMASK_OFFSTACK
1005	help
1006	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
1007	  If unsure, say N.
1008
1009#
1010# The maximum number of CPUs supported:
1011#
1012# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
1013# and which can be configured interactively in the
1014# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
1015#
1016# The ranges are different on 32-bit and 64-bit kernels, depending on
1017# hardware capabilities and scalability features of the kernel.
1018#
1019# ( If MAXSMP is enabled we just use the highest possible value and disable
1020#   interactive configuration. )
1021#
1022
1023config NR_CPUS_RANGE_BEGIN
1024	int
1025	default NR_CPUS_RANGE_END if MAXSMP
1026	default    1 if !SMP
1027	default    2
1028
1029config NR_CPUS_RANGE_END
1030	int
1031	depends on X86_32
1032	default    8 if  SMP
1033	default    1 if !SMP
1034
1035config NR_CPUS_RANGE_END
1036	int
1037	depends on X86_64
1038	default 8192 if  SMP && CPUMASK_OFFSTACK
1039	default  512 if  SMP && !CPUMASK_OFFSTACK
1040	default    1 if !SMP
1041
1042config NR_CPUS_DEFAULT
1043	int
1044	depends on X86_32
1045	default    8 if  SMP
1046	default    1 if !SMP
1047
1048config NR_CPUS_DEFAULT
1049	int
1050	depends on X86_64
1051	default 8192 if  MAXSMP
1052	default   64 if  SMP
1053	default    1 if !SMP
1054
1055config NR_CPUS
1056	int "Maximum number of CPUs" if SMP && !MAXSMP
1057	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1058	default NR_CPUS_DEFAULT
1059	help
1060	  This allows you to specify the maximum number of CPUs which this
1061	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1062	  supported value is 8192, otherwise the maximum value is 512.  The
1063	  minimum value which makes sense is 2.
1064
1065	  This is purely to save memory: each supported CPU adds about 8KB
1066	  to the kernel image.
1067
1068config SCHED_MC_PRIO
1069	bool "CPU core priorities scheduler support"
1070	depends on SCHED_MC
1071	select X86_INTEL_PSTATE if CPU_SUP_INTEL
1072	select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
1073	select CPU_FREQ
1074	default y
1075	help
1076	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1077	  core ordering determined at manufacturing time, which allows
1078	  certain cores to reach higher turbo frequencies (when running
1079	  single threaded workloads) than others.
1080
1081	  Enabling this kernel feature teaches the scheduler about
1082	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1083	  scheduler's CPU selection logic accordingly, so that higher
1084	  overall system performance can be achieved.
1085
1086	  This feature will have no effect on CPUs without this feature.
1087
1088	  If unsure say Y here.
1089
1090config UP_LATE_INIT
1091	def_bool y
1092	depends on !SMP && X86_LOCAL_APIC
1093
1094config X86_UP_APIC
1095	bool "Local APIC support on uniprocessors" if !PCI_MSI
1096	default PCI_MSI
1097	depends on X86_32 && !SMP
1098	help
1099	  A local APIC (Advanced Programmable Interrupt Controller) is an
1100	  integrated interrupt controller in the CPU. If you have a single-CPU
1101	  system which has a processor with a local APIC, you can say Y here to
1102	  enable and use it. If you say Y here even though your machine doesn't
1103	  have a local APIC, then the kernel will still run with no slowdown at
1104	  all. The local APIC supports CPU-generated self-interrupts (timer,
1105	  performance counters), and the NMI watchdog which detects hard
1106	  lockups.
1107
1108config X86_UP_IOAPIC
1109	bool "IO-APIC support on uniprocessors"
1110	depends on X86_UP_APIC
1111	help
1112	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1113	  SMP-capable replacement for PC-style interrupt controllers. Most
1114	  SMP systems and many recent uniprocessor systems have one.
1115
1116	  If you have a single-CPU system with an IO-APIC, you can say Y here
1117	  to use it. If you say Y here even though your machine doesn't have
1118	  an IO-APIC, then the kernel will still run with no slowdown at all.
1119
1120config X86_LOCAL_APIC
1121	def_bool y
1122	depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI
1123	select IRQ_DOMAIN_HIERARCHY
1124
1125config ACPI_MADT_WAKEUP
1126	def_bool y
1127	depends on X86_64
1128	depends on ACPI
1129	depends on SMP
1130	depends on X86_LOCAL_APIC
1131
1132config X86_IO_APIC
1133	def_bool y
1134	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1135
1136config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1137	bool "Reroute for broken boot IRQs"
1138	depends on X86_IO_APIC
1139	help
1140	  This option enables a workaround that fixes a source of
1141	  spurious interrupts. This is recommended when threaded
1142	  interrupt handling is used on systems where the generation of
1143	  superfluous "boot interrupts" cannot be disabled.
1144
1145	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1146	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1147	  kernel does during interrupt handling). On chipsets where this
1148	  boot IRQ generation cannot be disabled, this workaround keeps
1149	  the original IRQ line masked so that only the equivalent "boot
1150	  IRQ" is delivered to the CPUs. The workaround also tells the
1151	  kernel to set up the IRQ handler on the boot IRQ line. In this
1152	  way only one interrupt is delivered to the kernel. Otherwise
1153	  the spurious second interrupt may cause the kernel to bring
1154	  down (vital) interrupt lines.
1155
1156	  Only affects "broken" chipsets. Interrupt sharing may be
1157	  increased on these systems.
1158
1159config X86_MCE
1160	bool "Machine Check / overheating reporting"
1161	select GENERIC_ALLOCATOR
1162	default y
1163	help
1164	  Machine Check support allows the processor to notify the
1165	  kernel if it detects a problem (e.g. overheating, data corruption).
1166	  The action the kernel takes depends on the severity of the problem,
1167	  ranging from warning messages to halting the machine.
1168
1169config X86_MCELOG_LEGACY
1170	bool "Support for deprecated /dev/mcelog character device"
1171	depends on X86_MCE
1172	help
1173	  Enable support for /dev/mcelog which is needed by the old mcelog
1174	  userspace logging daemon. Consider switching to the new generation
1175	  rasdaemon solution.
1176
1177config X86_MCE_INTEL
1178	def_bool y
1179	prompt "Intel MCE features"
1180	depends on X86_MCE && X86_LOCAL_APIC
1181	help
1182	  Additional support for intel specific MCE features such as
1183	  the thermal monitor.
1184
1185config X86_MCE_AMD
1186	def_bool y
1187	prompt "AMD MCE features"
1188	depends on X86_MCE && X86_LOCAL_APIC
1189	help
1190	  Additional support for AMD specific MCE features such as
1191	  the DRAM Error Threshold.
1192
1193config X86_ANCIENT_MCE
1194	bool "Support for old Pentium 5 / WinChip machine checks"
1195	depends on X86_32 && X86_MCE
1196	help
1197	  Include support for machine check handling on old Pentium 5 or WinChip
1198	  systems. These typically need to be enabled explicitly on the command
1199	  line.
1200
1201config X86_MCE_THRESHOLD
1202	depends on X86_MCE_AMD || X86_MCE_INTEL
1203	def_bool y
1204
1205config X86_MCE_INJECT
1206	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1207	tristate "Machine check injector support"
1208	help
1209	  Provide support for injecting machine checks for testing purposes.
1210	  If you don't know what a machine check is and you don't do kernel
1211	  QA it is safe to say n.
1212
1213source "arch/x86/events/Kconfig"
1214
1215config X86_LEGACY_VM86
1216	bool "Legacy VM86 support"
1217	depends on X86_32
1218	help
1219	  This option allows user programs to put the CPU into V8086
1220	  mode, which is an 80286-era approximation of 16-bit real mode.
1221
1222	  Some very old versions of X and/or vbetool require this option
1223	  for user mode setting.  Similarly, DOSEMU will use it if
1224	  available to accelerate real mode DOS programs.  However, any
1225	  recent version of DOSEMU, X, or vbetool should be fully
1226	  functional even without kernel VM86 support, as they will all
1227	  fall back to software emulation. Nevertheless, if you are using
1228	  a 16-bit DOS program where 16-bit performance matters, vm86
1229	  mode might be faster than emulation and you might want to
1230	  enable this option.
1231
1232	  Note that any app that works on a 64-bit kernel is unlikely to
1233	  need this option, as 64-bit kernels don't, and can't, support
1234	  V8086 mode. This option is also unrelated to 16-bit protected
1235	  mode and is not needed to run most 16-bit programs under Wine.
1236
1237	  Enabling this option increases the complexity of the kernel
1238	  and slows down exception handling a tiny bit.
1239
1240	  If unsure, say N here.
1241
1242config VM86
1243	bool
1244	default X86_LEGACY_VM86
1245
1246config X86_16BIT
1247	bool "Enable support for 16-bit segments" if EXPERT
1248	default y
1249	depends on MODIFY_LDT_SYSCALL
1250	help
1251	  This option is required by programs like Wine to run 16-bit
1252	  protected mode legacy code on x86 processors.  Disabling
1253	  this option saves about 300 bytes on i386, or around 6K text
1254	  plus 16K runtime memory on x86-64,
1255
1256config X86_ESPFIX32
1257	def_bool y
1258	depends on X86_16BIT && X86_32
1259
1260config X86_ESPFIX64
1261	def_bool y
1262	depends on X86_16BIT && X86_64
1263
1264config X86_VSYSCALL_EMULATION
1265	bool "Enable vsyscall emulation" if EXPERT
1266	default y
1267	depends on X86_64
1268	help
1269	  This enables emulation of the legacy vsyscall page.  Disabling
1270	  it is roughly equivalent to booting with vsyscall=none, except
1271	  that it will also disable the helpful warning if a program
1272	  tries to use a vsyscall.  With this option set to N, offending
1273	  programs will just segfault, citing addresses of the form
1274	  0xffffffffff600?00.
1275
1276	  This option is required by many programs built before 2013, and
1277	  care should be used even with newer programs if set to N.
1278
1279	  Disabling this option saves about 7K of kernel size and
1280	  possibly 4K of additional runtime pagetable memory.
1281
1282config X86_IOPL_IOPERM
1283	bool "IOPERM and IOPL Emulation"
1284	default y
1285	help
1286	  This enables the ioperm() and iopl() syscalls which are necessary
1287	  for legacy applications.
1288
1289	  Legacy IOPL support is an overbroad mechanism which allows user
1290	  space aside of accessing all 65536 I/O ports also to disable
1291	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1292	  capabilities and permission from potentially active security
1293	  modules.
1294
1295	  The emulation restricts the functionality of the syscall to
1296	  only allowing the full range I/O port access, but prevents the
1297	  ability to disable interrupts from user space which would be
1298	  granted if the hardware IOPL mechanism would be used.
1299
1300config TOSHIBA
1301	tristate "Toshiba Laptop support"
1302	depends on X86_32
1303	help
1304	  This adds a driver to safely access the System Management Mode of
1305	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1306	  not work on models with a Phoenix BIOS. The System Management Mode
1307	  is used to set the BIOS and power saving options on Toshiba portables.
1308
1309	  For information on utilities to make use of this driver see the
1310	  Toshiba Linux utilities web site at:
1311	  <http://www.buzzard.org.uk/toshiba/>.
1312
1313	  Say Y if you intend to run this kernel on a Toshiba portable.
1314	  Say N otherwise.
1315
1316config X86_REBOOTFIXUPS
1317	bool "Enable X86 board specific fixups for reboot"
1318	depends on X86_32
1319	help
1320	  This enables chipset and/or board specific fixups to be done
1321	  in order to get reboot to work correctly. This is only needed on
1322	  some combinations of hardware and BIOS. The symptom, for which
1323	  this config is intended, is when reboot ends with a stalled/hung
1324	  system.
1325
1326	  Currently, the only fixup is for the Geode machines using
1327	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1328
1329	  Say Y if you want to enable the fixup. Currently, it's safe to
1330	  enable this option even if you don't need it.
1331	  Say N otherwise.
1332
1333config MICROCODE
1334	def_bool y
1335	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1336	select CRYPTO_LIB_SHA256 if CPU_SUP_AMD
1337
1338config MICROCODE_INITRD32
1339	def_bool y
1340	depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1341
1342config MICROCODE_LATE_LOADING
1343	bool "Late microcode loading (DANGEROUS)"
1344	default n
1345	depends on MICROCODE && SMP
1346	help
1347	  Loading microcode late, when the system is up and executing instructions
1348	  is a tricky business and should be avoided if possible. Just the sequence
1349	  of synchronizing all cores and SMT threads is one fragile dance which does
1350	  not guarantee that cores might not softlock after the loading. Therefore,
1351	  use this at your own risk. Late loading taints the kernel unless the
1352	  microcode header indicates that it is safe for late loading via the
1353	  minimal revision check. This minimal revision check can be enforced on
1354	  the kernel command line with "microcode=force_minrev".
1355
1356config MICROCODE_LATE_FORCE_MINREV
1357	bool "Enforce late microcode loading minimal revision check"
1358	default n
1359	depends on MICROCODE_LATE_LOADING
1360	help
1361	  To prevent that users load microcode late which modifies already
1362	  in use features, newer microcode patches have a minimum revision field
1363	  in the microcode header, which tells the kernel which minimum
1364	  revision must be active in the CPU to safely load that new microcode
1365	  late into the running system. If disabled the check will not
1366	  be enforced but the kernel will be tainted when the minimal
1367	  revision check fails.
1368
1369	  This minimal revision check can also be controlled via the
1370	  "microcode=force_minrev" parameter on the kernel command line.
1371
1372	  If unsure say Y.
1373
1374config MICROCODE_DBG
1375	bool "Enable microcode loader debugging"
1376	default n
1377	depends on MICROCODE
1378	help
1379	  Enable code which allows to debug the microcode loader. When running
1380	  in a guest the patch loading is simulated but everything else
1381	  related to patch parsing and handling is done as on baremetal with
1382	  the purpose of debugging solely the software side of things. On
1383	  baremetal, it simply dumps additional debugging information during
1384	  normal operation.
1385
1386	  You almost certainly want to say n here.
1387
1388config X86_MSR
1389	tristate "/dev/cpu/*/msr - Model-specific register support"
1390	help
1391	  This device gives privileged processes access to the x86
1392	  Model-Specific Registers (MSRs).  It is a character device with
1393	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1394	  MSR accesses are directed to a specific CPU on multi-processor
1395	  systems.
1396
1397config X86_CPUID
1398	tristate "/dev/cpu/*/cpuid - CPU information support"
1399	help
1400	  This device gives processes access to the x86 CPUID instruction to
1401	  be executed on a specific processor.  It is a character device
1402	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1403	  /dev/cpu/31/cpuid.
1404
1405config HIGHMEM4G
1406	bool "High Memory Support"
1407	depends on X86_32
1408	help
1409	  Linux can use up to 4 Gigabytes of physical memory on x86 systems.
1410	  However, the address space of 32-bit x86 processors is only 4
1411	  Gigabytes large. That means that, if you have a large amount of
1412	  physical memory, not all of it can be "permanently mapped" by the
1413	  kernel. The physical memory that's not permanently mapped is called
1414	  "high memory".
1415
1416	  If you are compiling a kernel which will never run on a machine with
1417	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1418	  choice and suitable for most users). This will result in a "3GB/1GB"
1419	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1420	  space and the remaining part of the 4GB virtual memory space is used
1421	  by the kernel to permanently map as much physical memory as
1422	  possible.
1423
1424	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1425	  answer "Y" here.
1426
1427	  If unsure, say N.
1428
1429choice
1430	prompt "Memory split" if EXPERT
1431	default VMSPLIT_3G
1432	depends on X86_32
1433	help
1434	  Select the desired split between kernel and user memory.
1435
1436	  If the address range available to the kernel is less than the
1437	  physical memory installed, the remaining memory will be available
1438	  as "high memory". Accessing high memory is a little more costly
1439	  than low memory, as it needs to be mapped into the kernel first.
1440	  Note that increasing the kernel address space limits the range
1441	  available to user programs, making the address space there
1442	  tighter.  Selecting anything other than the default 3G/1G split
1443	  will also likely make your kernel incompatible with binary-only
1444	  kernel modules.
1445
1446	  If you are not absolutely sure what you are doing, leave this
1447	  option alone!
1448
1449	config VMSPLIT_3G
1450		bool "3G/1G user/kernel split"
1451	config VMSPLIT_3G_OPT
1452		depends on !X86_PAE
1453		bool "3G/1G user/kernel split (for full 1G low memory)"
1454	config VMSPLIT_2G
1455		bool "2G/2G user/kernel split"
1456	config VMSPLIT_2G_OPT
1457		depends on !X86_PAE
1458		bool "2G/2G user/kernel split (for full 2G low memory)"
1459	config VMSPLIT_1G
1460		bool "1G/3G user/kernel split"
1461endchoice
1462
1463config PAGE_OFFSET
1464	hex
1465	default 0xB0000000 if VMSPLIT_3G_OPT
1466	default 0x80000000 if VMSPLIT_2G
1467	default 0x78000000 if VMSPLIT_2G_OPT
1468	default 0x40000000 if VMSPLIT_1G
1469	default 0xC0000000
1470	depends on X86_32
1471
1472config HIGHMEM
1473	def_bool HIGHMEM4G
1474
1475config X86_PAE
1476	bool "PAE (Physical Address Extension) Support"
1477	depends on X86_32 && X86_HAVE_PAE
1478	select PHYS_ADDR_T_64BIT
1479	help
1480	  PAE is required for NX support, and furthermore enables
1481	  larger swapspace support for non-overcommit purposes. It
1482	  has the cost of more pagetable lookup overhead, and also
1483	  consumes more pagetable space per process.
1484
1485config X86_DIRECT_GBPAGES
1486	def_bool y
1487	depends on X86_64
1488	help
1489	  Certain kernel features effectively disable kernel
1490	  linear 1 GB mappings (even if the CPU otherwise
1491	  supports them), so don't confuse the user by printing
1492	  that we have them enabled.
1493
1494config X86_CPA_STATISTICS
1495	bool "Enable statistic for Change Page Attribute"
1496	depends on DEBUG_FS
1497	help
1498	  Expose statistics about the Change Page Attribute mechanism, which
1499	  helps to determine the effectiveness of preserving large and huge
1500	  page mappings when mapping protections are changed.
1501
1502config X86_MEM_ENCRYPT
1503	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1504	select DYNAMIC_PHYSICAL_MASK
1505	def_bool n
1506
1507config AMD_MEM_ENCRYPT
1508	bool "AMD Secure Memory Encryption (SME) support"
1509	depends on X86_64 && CPU_SUP_AMD
1510	depends on EFI_STUB
1511	select DMA_COHERENT_POOL
1512	select ARCH_USE_MEMREMAP_PROT
1513	select INSTRUCTION_DECODER
1514	select ARCH_HAS_CC_PLATFORM
1515	select X86_MEM_ENCRYPT
1516	select UNACCEPTED_MEMORY
1517	select CRYPTO_LIB_AESGCM
1518	help
1519	  Say yes to enable support for the encryption of system memory.
1520	  This requires an AMD processor that supports Secure Memory
1521	  Encryption (SME).
1522
1523# Common NUMA Features
1524config NUMA
1525	bool "NUMA Memory Allocation and Scheduler Support"
1526	depends on SMP
1527	depends on X86_64
1528	select USE_PERCPU_NUMA_NODE_ID
1529	select OF_NUMA if OF
1530	help
1531	  Enable NUMA (Non-Uniform Memory Access) support.
1532
1533	  The kernel will try to allocate memory used by a CPU on the
1534	  local memory controller of the CPU and add some more
1535	  NUMA awareness to the kernel.
1536
1537	  For 64-bit this is recommended if the system is Intel Core i7
1538	  (or later), AMD Opteron, or EM64T NUMA.
1539
1540	  Otherwise, you should say N.
1541
1542config AMD_NUMA
1543	def_bool y
1544	prompt "Old style AMD Opteron NUMA detection"
1545	depends on X86_64 && NUMA && PCI
1546	help
1547	  Enable AMD NUMA node topology detection.  You should say Y here if
1548	  you have a multi processor AMD system. This uses an old method to
1549	  read the NUMA configuration directly from the builtin Northbridge
1550	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1551	  which also takes priority if both are compiled in.
1552
1553config X86_64_ACPI_NUMA
1554	def_bool y
1555	prompt "ACPI NUMA detection"
1556	depends on X86_64 && NUMA && ACPI && PCI
1557	select ACPI_NUMA
1558	help
1559	  Enable ACPI SRAT based node topology detection.
1560
1561config NODES_SHIFT
1562	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1563	range 1 10
1564	default "10" if MAXSMP
1565	default "6" if X86_64
1566	default "3"
1567	depends on NUMA
1568	help
1569	  Specify the maximum number of NUMA Nodes available on the target
1570	  system.  Increases memory reserved to accommodate various tables.
1571
1572config ARCH_FLATMEM_ENABLE
1573	def_bool y
1574	depends on X86_32 && !NUMA
1575
1576config ARCH_SPARSEMEM_ENABLE
1577	def_bool y
1578	select SPARSEMEM_STATIC if X86_32
1579	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1580
1581config ARCH_SPARSEMEM_DEFAULT
1582	def_bool X86_64 || (NUMA && X86_32)
1583
1584config ARCH_SELECT_MEMORY_MODEL
1585	def_bool y
1586	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1587
1588config ARCH_MEMORY_PROBE
1589	bool "Enable sysfs memory/probe interface"
1590	depends on MEMORY_HOTPLUG
1591	help
1592	  This option enables a sysfs memory/probe interface for testing.
1593	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1594	  If you are unsure how to answer this question, answer N.
1595
1596config ARCH_PROC_KCORE_TEXT
1597	def_bool y
1598	depends on X86_64 && PROC_KCORE
1599
1600config ILLEGAL_POINTER_VALUE
1601	hex
1602	default 0 if X86_32
1603	default 0xdead000000000000 if X86_64
1604
1605config X86_PMEM_LEGACY_DEVICE
1606	bool
1607
1608config X86_PMEM_LEGACY
1609	tristate "Support non-standard NVDIMMs and ADR protected memory"
1610	depends on PHYS_ADDR_T_64BIT
1611	depends on BLK_DEV
1612	select X86_PMEM_LEGACY_DEVICE
1613	select NUMA_KEEP_MEMINFO if NUMA
1614	select LIBNVDIMM
1615	help
1616	  Treat memory marked using the non-standard e820 type of 12 as used
1617	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1618	  The kernel will offer these regions to the 'pmem' driver so
1619	  they can be used for persistent storage.
1620
1621	  Say Y if unsure.
1622
1623config X86_CHECK_BIOS_CORRUPTION
1624	bool "Check for low memory corruption"
1625	help
1626	  Periodically check for memory corruption in low memory, which
1627	  is suspected to be caused by BIOS.  Even when enabled in the
1628	  configuration, it is disabled at runtime.  Enable it by
1629	  setting "memory_corruption_check=1" on the kernel command
1630	  line.  By default it scans the low 64k of memory every 60
1631	  seconds; see the memory_corruption_check_size and
1632	  memory_corruption_check_period parameters in
1633	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1634
1635	  When enabled with the default parameters, this option has
1636	  almost no overhead, as it reserves a relatively small amount
1637	  of memory and scans it infrequently.  It both detects corruption
1638	  and prevents it from affecting the running system.
1639
1640	  It is, however, intended as a diagnostic tool; if repeatable
1641	  BIOS-originated corruption always affects the same memory,
1642	  you can use memmap= to prevent the kernel from using that
1643	  memory.
1644
1645config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1646	bool "Set the default setting of memory_corruption_check"
1647	depends on X86_CHECK_BIOS_CORRUPTION
1648	default y
1649	help
1650	  Set whether the default state of memory_corruption_check is
1651	  on or off.
1652
1653config MATH_EMULATION
1654	bool
1655	depends on MODIFY_LDT_SYSCALL
1656	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1657	help
1658	  Linux can emulate a math coprocessor (used for floating point
1659	  operations) if you don't have one. 486DX and Pentium processors have
1660	  a math coprocessor built in, 486SX and 386 do not, unless you added
1661	  a 487DX or 387, respectively. (The messages during boot time can
1662	  give you some hints here ["man dmesg"].) Everyone needs either a
1663	  coprocessor or this emulation.
1664
1665	  If you don't have a math coprocessor, you need to say Y here; if you
1666	  say Y here even though you have a coprocessor, the coprocessor will
1667	  be used nevertheless. (This behavior can be changed with the kernel
1668	  command line option "no387", which comes handy if your coprocessor
1669	  is broken. Try "man bootparam" or see the documentation of your boot
1670	  loader (lilo or loadlin) about how to pass options to the kernel at
1671	  boot time.) This means that it is a good idea to say Y here if you
1672	  intend to use this kernel on different machines.
1673
1674	  More information about the internals of the Linux math coprocessor
1675	  emulation can be found in <file:arch/x86/math-emu/README>.
1676
1677	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1678	  kernel, it won't hurt.
1679
1680config MTRR
1681	def_bool y
1682	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1683	help
1684	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1685	  the Memory Type Range Registers (MTRRs) may be used to control
1686	  processor access to memory ranges. This is most useful if you have
1687	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1688	  allows bus write transfers to be combined into a larger transfer
1689	  before bursting over the PCI/AGP bus. This can increase performance
1690	  of image write operations 2.5 times or more. Saying Y here creates a
1691	  /proc/mtrr file which may be used to manipulate your processor's
1692	  MTRRs. Typically the X server should use this.
1693
1694	  This code has a reasonably generic interface so that similar
1695	  control registers on other processors can be easily supported
1696	  as well:
1697
1698	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1699	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1700	  these, the ARRs are used to emulate the MTRRs.
1701	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1702	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1703	  write-combining. All of these processors are supported by this code
1704	  and it makes sense to say Y here if you have one of them.
1705
1706	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1707	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1708	  can lead to all sorts of problems, so it's good to say Y here.
1709
1710	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1711	  just add about 9 KB to your kernel.
1712
1713	  See <file:Documentation/arch/x86/mtrr.rst> for more information.
1714
1715config MTRR_SANITIZER
1716	def_bool y
1717	prompt "MTRR cleanup support"
1718	depends on MTRR
1719	help
1720	  Convert MTRR layout from continuous to discrete, so X drivers can
1721	  add writeback entries.
1722
1723	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1724	  The largest mtrr entry size for a continuous block can be set with
1725	  mtrr_chunk_size.
1726
1727	  If unsure, say Y.
1728
1729config MTRR_SANITIZER_ENABLE_DEFAULT
1730	int "MTRR cleanup enable value (0-1)"
1731	range 0 1
1732	default "0"
1733	depends on MTRR_SANITIZER
1734	help
1735	  Enable mtrr cleanup default value
1736
1737config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1738	int "MTRR cleanup spare reg num (0-7)"
1739	range 0 7
1740	default "1"
1741	depends on MTRR_SANITIZER
1742	help
1743	  mtrr cleanup spare entries default, it can be changed via
1744	  mtrr_spare_reg_nr=N on the kernel command line.
1745
1746config X86_PAT
1747	def_bool y
1748	prompt "x86 PAT support" if EXPERT
1749	depends on MTRR
1750	select ARCH_USES_PG_ARCH_2
1751	help
1752	  Use PAT attributes to setup page level cache control.
1753
1754	  PATs are the modern equivalents of MTRRs and are much more
1755	  flexible than MTRRs.
1756
1757	  Say N here if you see bootup problems (boot crash, boot hang,
1758	  spontaneous reboots) or a non-working video driver.
1759
1760	  If unsure, say Y.
1761
1762config X86_UMIP
1763	def_bool y
1764	prompt "User Mode Instruction Prevention" if EXPERT
1765	help
1766	  User Mode Instruction Prevention (UMIP) is a security feature in
1767	  some x86 processors. If enabled, a general protection fault is
1768	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1769	  executed in user mode. These instructions unnecessarily expose
1770	  information about the hardware state.
1771
1772	  The vast majority of applications do not use these instructions.
1773	  For the very few that do, software emulation is provided in
1774	  specific cases in protected and virtual-8086 modes. Emulated
1775	  results are dummy.
1776
1777config CC_HAS_IBT
1778	# GCC >= 9 and binutils >= 2.29
1779	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1780	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || CC_IS_CLANG) && \
1781		  $(as-instr,endbr64)
1782
1783config X86_CET
1784	def_bool n
1785	help
1786	  CET features configured (Shadow stack or IBT)
1787
1788config X86_KERNEL_IBT
1789	prompt "Indirect Branch Tracking"
1790	def_bool y
1791	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1792	select OBJTOOL
1793	select X86_CET
1794	help
1795	  Build the kernel with support for Indirect Branch Tracking, a
1796	  hardware support course-grain forward-edge Control Flow Integrity
1797	  protection. It enforces that all indirect calls must land on
1798	  an ENDBR instruction, as such, the compiler will instrument the
1799	  code with them to make this happen.
1800
1801	  In addition to building the kernel with IBT, seal all functions that
1802	  are not indirect call targets, avoiding them ever becoming one.
1803
1804	  This requires LTO like objtool runs and will slow down the build. It
1805	  does significantly reduce the number of ENDBR instructions in the
1806	  kernel image.
1807
1808config X86_INTEL_MEMORY_PROTECTION_KEYS
1809	prompt "Memory Protection Keys"
1810	def_bool y
1811	# Note: only available in 64-bit mode
1812	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1813	select ARCH_USES_HIGH_VMA_FLAGS
1814	select ARCH_HAS_PKEYS
1815	help
1816	  Memory Protection Keys provides a mechanism for enforcing
1817	  page-based protections, but without requiring modification of the
1818	  page tables when an application changes protection domains.
1819
1820	  For details, see Documentation/core-api/protection-keys.rst
1821
1822	  If unsure, say y.
1823
1824config ARCH_PKEY_BITS
1825	int
1826	default 4
1827
1828choice
1829	prompt "TSX enable mode"
1830	depends on CPU_SUP_INTEL
1831	default X86_INTEL_TSX_MODE_AUTO
1832	help
1833	  Intel's TSX (Transactional Synchronization Extensions) feature
1834	  allows to optimize locking protocols through lock elision which
1835	  can lead to a noticeable performance boost.
1836
1837	  On the other hand it has been shown that TSX can be exploited
1838	  to form side channel attacks (e.g. TAA) and chances are there
1839	  will be more of those attacks discovered in the future.
1840
1841	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1842	  might override this decision by tsx=on the command line parameter.
1843	  Even with TSX enabled, the kernel will attempt to enable the best
1844	  possible TAA mitigation setting depending on the microcode available
1845	  for the particular machine.
1846
1847	  This option allows to set the default tsx mode between tsx=on, =off
1848	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1849	  details.
1850
1851	  Say off if not sure, auto if TSX is in use but it should be used on safe
1852	  platforms or on if TSX is in use and the security aspect of tsx is not
1853	  relevant.
1854
1855config X86_INTEL_TSX_MODE_OFF
1856	bool "off"
1857	help
1858	  TSX is disabled if possible - equals to tsx=off command line parameter.
1859
1860config X86_INTEL_TSX_MODE_ON
1861	bool "on"
1862	help
1863	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1864	  line parameter.
1865
1866config X86_INTEL_TSX_MODE_AUTO
1867	bool "auto"
1868	help
1869	  TSX is enabled on TSX capable HW that is believed to be safe against
1870	  side channel attacks- equals the tsx=auto command line parameter.
1871endchoice
1872
1873config X86_SGX
1874	bool "Software Guard eXtensions (SGX)"
1875	depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1876	select CRYPTO_LIB_SHA256
1877	select MMU_NOTIFIER
1878	select NUMA_KEEP_MEMINFO if NUMA
1879	select XARRAY_MULTI
1880	help
1881	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1882	  that can be used by applications to set aside private regions of code
1883	  and data, referred to as enclaves. An enclave's private memory can
1884	  only be accessed by code running within the enclave. Accesses from
1885	  outside the enclave, including other enclaves, are disallowed by
1886	  hardware.
1887
1888	  If unsure, say N.
1889
1890config X86_USER_SHADOW_STACK
1891	bool "X86 userspace shadow stack"
1892	depends on AS_WRUSS
1893	depends on X86_64
1894	select ARCH_USES_HIGH_VMA_FLAGS
1895	select ARCH_HAS_USER_SHADOW_STACK
1896	select X86_CET
1897	help
1898	  Shadow stack protection is a hardware feature that detects function
1899	  return address corruption.  This helps mitigate ROP attacks.
1900	  Applications must be enabled to use it, and old userspace does not
1901	  get protection "for free".
1902
1903	  CPUs supporting shadow stacks were first released in 2020.
1904
1905	  See Documentation/arch/x86/shstk.rst for more information.
1906
1907	  If unsure, say N.
1908
1909config INTEL_TDX_HOST
1910	bool "Intel Trust Domain Extensions (TDX) host support"
1911	depends on CPU_SUP_INTEL
1912	depends on X86_64
1913	depends on KVM_INTEL
1914	depends on X86_X2APIC
1915	select ARCH_KEEP_MEMBLOCK
1916	depends on CONTIG_ALLOC
1917	depends on X86_MCE
1918	help
1919	  Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1920	  host and certain physical attacks.  This option enables necessary TDX
1921	  support in the host kernel to run confidential VMs.
1922
1923	  If unsure, say N.
1924
1925config EFI
1926	bool "EFI runtime service support"
1927	depends on ACPI
1928	select UCS2_STRING
1929	select EFI_RUNTIME_WRAPPERS
1930	select ARCH_USE_MEMREMAP_PROT
1931	select EFI_RUNTIME_MAP if KEXEC_CORE
1932	help
1933	  This enables the kernel to use EFI runtime services that are
1934	  available (such as the EFI variable services).
1935
1936	  This option is only useful on systems that have EFI firmware.
1937	  In addition, you should use the latest ELILO loader available
1938	  at <http://elilo.sourceforge.net> in order to take advantage
1939	  of EFI runtime services. However, even with this option, the
1940	  resultant kernel should continue to boot on existing non-EFI
1941	  platforms.
1942
1943config EFI_STUB
1944	bool "EFI stub support"
1945	depends on EFI
1946	select RELOCATABLE
1947	help
1948	  This kernel feature allows a bzImage to be loaded directly
1949	  by EFI firmware without the use of a bootloader.
1950
1951	  See Documentation/admin-guide/efi-stub.rst for more information.
1952
1953config EFI_HANDOVER_PROTOCOL
1954	bool "EFI handover protocol (DEPRECATED)"
1955	depends on EFI_STUB
1956	default y
1957	help
1958	  Select this in order to include support for the deprecated EFI
1959	  handover protocol, which defines alternative entry points into the
1960	  EFI stub.  This is a practice that has no basis in the UEFI
1961	  specification, and requires a priori knowledge on the part of the
1962	  bootloader about Linux/x86 specific ways of passing the command line
1963	  and initrd, and where in memory those assets may be loaded.
1964
1965	  If in doubt, say Y. Even though the corresponding support is not
1966	  present in upstream GRUB or other bootloaders, most distros build
1967	  GRUB with numerous downstream patches applied, and may rely on the
1968	  handover protocol as as result.
1969
1970config EFI_MIXED
1971	bool "EFI mixed-mode support"
1972	depends on EFI_STUB && X86_64
1973	help
1974	  Enabling this feature allows a 64-bit kernel to be booted
1975	  on a 32-bit firmware, provided that your CPU supports 64-bit
1976	  mode.
1977
1978	  Note that it is not possible to boot a mixed-mode enabled
1979	  kernel via the EFI boot stub - a bootloader that supports
1980	  the EFI handover protocol must be used.
1981
1982	  If unsure, say N.
1983
1984config EFI_RUNTIME_MAP
1985	bool "Export EFI runtime maps to sysfs" if EXPERT
1986	depends on EFI
1987	help
1988	  Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
1989	  That memory map is required by the 2nd kernel to set up EFI virtual
1990	  mappings after kexec, but can also be used for debugging purposes.
1991
1992	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
1993
1994source "kernel/Kconfig.hz"
1995
1996config ARCH_SUPPORTS_KEXEC
1997	def_bool y
1998
1999config ARCH_SUPPORTS_KEXEC_FILE
2000	def_bool X86_64
2001
2002config ARCH_SELECTS_KEXEC_FILE
2003	def_bool y
2004	depends on KEXEC_FILE
2005	select HAVE_IMA_KEXEC if IMA
2006
2007config ARCH_SUPPORTS_KEXEC_PURGATORY
2008	def_bool y
2009
2010config ARCH_SUPPORTS_KEXEC_SIG
2011	def_bool y
2012
2013config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2014	def_bool y
2015
2016config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2017	def_bool y
2018
2019config ARCH_SUPPORTS_KEXEC_JUMP
2020	def_bool y
2021
2022config ARCH_SUPPORTS_KEXEC_HANDOVER
2023	def_bool X86_64
2024
2025config ARCH_SUPPORTS_CRASH_DUMP
2026	def_bool X86_64 || (X86_32 && HIGHMEM)
2027
2028config ARCH_DEFAULT_CRASH_DUMP
2029	def_bool y
2030
2031config ARCH_SUPPORTS_CRASH_HOTPLUG
2032	def_bool y
2033
2034config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2035	def_bool CRASH_RESERVE
2036
2037config PHYSICAL_START
2038	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2039	default "0x1000000"
2040	help
2041	  This gives the physical address where the kernel is loaded.
2042
2043	  If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2044	  will decompress itself to above physical address and run from there.
2045	  Otherwise, bzImage will run from the address where it has been loaded
2046	  by the boot loader. The only exception is if it is loaded below the
2047	  above physical address, in which case it will relocate itself there.
2048
2049	  In normal kdump cases one does not have to set/change this option
2050	  as now bzImage can be compiled as a completely relocatable image
2051	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2052	  address. This option is mainly useful for the folks who don't want
2053	  to use a bzImage for capturing the crash dump and want to use a
2054	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2055	  to be specifically compiled to run from a specific memory area
2056	  (normally a reserved region) and this option comes handy.
2057
2058	  So if you are using bzImage for capturing the crash dump,
2059	  leave the value here unchanged to 0x1000000 and set
2060	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2061	  for capturing the crash dump change this value to start of
2062	  the reserved region.  In other words, it can be set based on
2063	  the "X" value as specified in the "crashkernel=YM@XM"
2064	  command line boot parameter passed to the panic-ed
2065	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2066	  for more details about crash dumps.
2067
2068	  Usage of bzImage for capturing the crash dump is recommended as
2069	  one does not have to build two kernels. Same kernel can be used
2070	  as production kernel and capture kernel. Above option should have
2071	  gone away after relocatable bzImage support is introduced. But it
2072	  is present because there are users out there who continue to use
2073	  vmlinux for dump capture. This option should go away down the
2074	  line.
2075
2076	  Don't change this unless you know what you are doing.
2077
2078config RELOCATABLE
2079	bool "Build a relocatable kernel"
2080	default y
2081	help
2082	  This builds a kernel image that retains relocation information
2083	  so it can be loaded someplace besides the default 1MB.
2084	  The relocations tend to make the kernel binary about 10% larger,
2085	  but are discarded at runtime.
2086
2087	  One use is for the kexec on panic case where the recovery kernel
2088	  must live at a different physical address than the primary
2089	  kernel.
2090
2091	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2092	  it has been loaded at and the compile time physical address
2093	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2094
2095config RANDOMIZE_BASE
2096	bool "Randomize the address of the kernel image (KASLR)"
2097	depends on RELOCATABLE
2098	default y
2099	help
2100	  In support of Kernel Address Space Layout Randomization (KASLR),
2101	  this randomizes the physical address at which the kernel image
2102	  is decompressed and the virtual address where the kernel
2103	  image is mapped, as a security feature that deters exploit
2104	  attempts relying on knowledge of the location of kernel
2105	  code internals.
2106
2107	  On 64-bit, the kernel physical and virtual addresses are
2108	  randomized separately. The physical address will be anywhere
2109	  between 16MB and the top of physical memory (up to 64TB). The
2110	  virtual address will be randomized from 16MB up to 1GB (9 bits
2111	  of entropy). Note that this also reduces the memory space
2112	  available to kernel modules from 1.5GB to 1GB.
2113
2114	  On 32-bit, the kernel physical and virtual addresses are
2115	  randomized together. They will be randomized from 16MB up to
2116	  512MB (8 bits of entropy).
2117
2118	  Entropy is generated using the RDRAND instruction if it is
2119	  supported. If RDTSC is supported, its value is mixed into
2120	  the entropy pool as well. If neither RDRAND nor RDTSC are
2121	  supported, then entropy is read from the i8254 timer. The
2122	  usable entropy is limited by the kernel being built using
2123	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2124	  minimum of 2MB. As a result, only 10 bits of entropy are
2125	  theoretically possible, but the implementations are further
2126	  limited due to memory layouts.
2127
2128	  If unsure, say Y.
2129
2130# Relocation on x86 needs some additional build support
2131config X86_NEED_RELOCS
2132	def_bool y
2133	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2134	select ARCH_VMLINUX_NEEDS_RELOCS
2135
2136config PHYSICAL_ALIGN
2137	hex "Alignment value to which kernel should be aligned"
2138	default "0x200000"
2139	range 0x2000 0x1000000 if X86_32
2140	range 0x200000 0x1000000 if X86_64
2141	help
2142	  This value puts the alignment restrictions on physical address
2143	  where kernel is loaded and run from. Kernel is compiled for an
2144	  address which meets above alignment restriction.
2145
2146	  If bootloader loads the kernel at a non-aligned address and
2147	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2148	  address aligned to above value and run from there.
2149
2150	  If bootloader loads the kernel at a non-aligned address and
2151	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2152	  load address and decompress itself to the address it has been
2153	  compiled for and run from there. The address for which kernel is
2154	  compiled already meets above alignment restrictions. Hence the
2155	  end result is that kernel runs from a physical address meeting
2156	  above alignment restrictions.
2157
2158	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2159	  this value must be a multiple of 0x200000.
2160
2161	  Don't change this unless you know what you are doing.
2162
2163config RANDOMIZE_MEMORY
2164	bool "Randomize the kernel memory sections"
2165	depends on X86_64
2166	depends on RANDOMIZE_BASE
2167	default RANDOMIZE_BASE
2168	help
2169	  Randomizes the base virtual address of kernel memory sections
2170	  (physical memory mapping, vmalloc & vmemmap). This security feature
2171	  makes exploits relying on predictable memory locations less reliable.
2172
2173	  The order of allocations remains unchanged. Entropy is generated in
2174	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2175	  configuration have in average 30,000 different possible virtual
2176	  addresses for each memory section.
2177
2178	  If unsure, say Y.
2179
2180config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2181	hex "Physical memory mapping padding" if EXPERT
2182	depends on RANDOMIZE_MEMORY
2183	default "0xa" if MEMORY_HOTPLUG
2184	default "0x0"
2185	range 0x1 0x40 if MEMORY_HOTPLUG
2186	range 0x0 0x40
2187	help
2188	  Define the padding in terabytes added to the existing physical
2189	  memory size during kernel memory randomization. It is useful
2190	  for memory hotplug support but reduces the entropy available for
2191	  address randomization.
2192
2193	  If unsure, leave at the default value.
2194
2195config ADDRESS_MASKING
2196	bool "Linear Address Masking support"
2197	depends on X86_64
2198	depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
2199	help
2200	  Linear Address Masking (LAM) modifies the checking that is applied
2201	  to 64-bit linear addresses, allowing software to use of the
2202	  untranslated address bits for metadata.
2203
2204	  The capability can be used for efficient address sanitizers (ASAN)
2205	  implementation and for optimizations in JITs.
2206
2207config HOTPLUG_CPU
2208	def_bool y
2209	depends on SMP
2210
2211config COMPAT_VDSO
2212	def_bool n
2213	prompt "Workaround for glibc 2.3.2 / 2.3.3 (released in year 2003/2004)"
2214	depends on COMPAT_32
2215	help
2216	  Certain buggy versions of glibc will crash if they are
2217	  presented with a 32-bit vDSO that is not mapped at the address
2218	  indicated in its segment table.
2219
2220	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2221	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2222	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2223	  the only released version with the bug, but OpenSUSE 9
2224	  contains a buggy "glibc 2.3.2".
2225
2226	  The symptom of the bug is that everything crashes on startup, saying:
2227	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2228
2229	  Saying Y here changes the default value of the vdso32 boot
2230	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2231	  This works around the glibc bug but hurts performance.
2232
2233	  If unsure, say N: if you are compiling your own kernel, you
2234	  are unlikely to be using a buggy version of glibc.
2235
2236choice
2237	prompt "vsyscall table for legacy applications"
2238	depends on X86_64
2239	default LEGACY_VSYSCALL_XONLY
2240	help
2241	  Legacy user code that does not know how to find the vDSO expects
2242	  to be able to issue three syscalls by calling fixed addresses in
2243	  kernel space. Since this location is not randomized with ASLR,
2244	  it can be used to assist security vulnerability exploitation.
2245
2246	  This setting can be changed at boot time via the kernel command
2247	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2248	  is deprecated and can only be enabled using the kernel command
2249	  line.
2250
2251	  On a system with recent enough glibc (2.14 or newer) and no
2252	  static binaries, you can say None without a performance penalty
2253	  to improve security.
2254
2255	  If unsure, select "Emulate execution only".
2256
2257	config LEGACY_VSYSCALL_XONLY
2258		bool "Emulate execution only"
2259		help
2260		  The kernel traps and emulates calls into the fixed vsyscall
2261		  address mapping and does not allow reads.  This
2262		  configuration is recommended when userspace might use the
2263		  legacy vsyscall area but support for legacy binary
2264		  instrumentation of legacy code is not needed.  It mitigates
2265		  certain uses of the vsyscall area as an ASLR-bypassing
2266		  buffer.
2267
2268	config LEGACY_VSYSCALL_NONE
2269		bool "None"
2270		help
2271		  There will be no vsyscall mapping at all. This will
2272		  eliminate any risk of ASLR bypass due to the vsyscall
2273		  fixed address mapping. Attempts to use the vsyscalls
2274		  will be reported to dmesg, so that either old or
2275		  malicious userspace programs can be identified.
2276
2277endchoice
2278
2279config CMDLINE_BOOL
2280	bool "Built-in kernel command line"
2281	help
2282	  Allow for specifying boot arguments to the kernel at
2283	  build time.  On some systems (e.g. embedded ones), it is
2284	  necessary or convenient to provide some or all of the
2285	  kernel boot arguments with the kernel itself (that is,
2286	  to not rely on the boot loader to provide them.)
2287
2288	  To compile command line arguments into the kernel,
2289	  set this option to 'Y', then fill in the
2290	  boot arguments in CONFIG_CMDLINE.
2291
2292	  Systems with fully functional boot loaders (i.e. non-embedded)
2293	  should leave this option set to 'N'.
2294
2295config CMDLINE
2296	string "Built-in kernel command string"
2297	depends on CMDLINE_BOOL
2298	default ""
2299	help
2300	  Enter arguments here that should be compiled into the kernel
2301	  image and used at boot time.  If the boot loader provides a
2302	  command line at boot time, it is appended to this string to
2303	  form the full kernel command line, when the system boots.
2304
2305	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2306	  change this behavior.
2307
2308	  In most cases, the command line (whether built-in or provided
2309	  by the boot loader) should specify the device for the root
2310	  file system.
2311
2312config CMDLINE_OVERRIDE
2313	bool "Built-in command line overrides boot loader arguments"
2314	depends on CMDLINE_BOOL && CMDLINE != ""
2315	help
2316	  Set this option to 'Y' to have the kernel ignore the boot loader
2317	  command line, and use ONLY the built-in command line.
2318
2319	  This is used to work around broken boot loaders.  This should
2320	  be set to 'N' under normal conditions.
2321
2322config MODIFY_LDT_SYSCALL
2323	bool "Enable the LDT (local descriptor table)" if EXPERT
2324	default y
2325	help
2326	  Linux can allow user programs to install a per-process x86
2327	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2328	  call.  This is required to run 16-bit or segmented code such as
2329	  DOSEMU or some Wine programs.  It is also used by some very old
2330	  threading libraries.
2331
2332	  Enabling this feature adds a small amount of overhead to
2333	  context switches and increases the low-level kernel attack
2334	  surface.  Disabling it removes the modify_ldt(2) system call.
2335
2336	  Saying 'N' here may make sense for embedded or server kernels.
2337
2338config STRICT_SIGALTSTACK_SIZE
2339	bool "Enforce strict size checking for sigaltstack"
2340	depends on DYNAMIC_SIGFRAME
2341	help
2342	  For historical reasons MINSIGSTKSZ is a constant which became
2343	  already too small with AVX512 support. Add a mechanism to
2344	  enforce strict checking of the sigaltstack size against the
2345	  real size of the FPU frame. This option enables the check
2346	  by default. It can also be controlled via the kernel command
2347	  line option 'strict_sas_size' independent of this config
2348	  switch. Enabling it might break existing applications which
2349	  allocate a too small sigaltstack but 'work' because they
2350	  never get a signal delivered.
2351
2352	  Say 'N' unless you want to really enforce this check.
2353
2354config CFI_AUTO_DEFAULT
2355	bool "Attempt to use FineIBT by default at boot time"
2356	depends on FINEIBT
2357	depends on !RUST || RUSTC_VERSION >= 108800
2358	default y
2359	help
2360	  Attempt to use FineIBT by default at boot time. If enabled,
2361	  this is the same as booting with "cfi=auto". If disabled,
2362	  this is the same as booting with "cfi=kcfi".
2363
2364source "kernel/livepatch/Kconfig"
2365
2366config X86_BUS_LOCK_DETECT
2367	bool "Split Lock Detect and Bus Lock Detect support"
2368	depends on CPU_SUP_INTEL || CPU_SUP_AMD
2369	default y
2370	help
2371	  Enable Split Lock Detect and Bus Lock Detect functionalities.
2372	  See <file:Documentation/arch/x86/buslock.rst> for more information.
2373
2374endmenu
2375
2376config CC_HAS_NAMED_AS
2377	def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
2378	depends on CC_IS_GCC
2379
2380#
2381# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN)
2382# are incompatible with named address spaces with GCC < 13.3
2383# (see GCC PR sanitizer/111736 and also PR sanitizer/115172).
2384#
2385
2386config CC_HAS_NAMED_AS_FIXED_SANITIZERS
2387	def_bool y
2388	depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300
2389	depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200
2390
2391config USE_X86_SEG_SUPPORT
2392	def_bool CC_HAS_NAMED_AS
2393	depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS
2394
2395config CC_HAS_SLS
2396	def_bool $(cc-option,-mharden-sls=all)
2397
2398config CC_HAS_RETURN_THUNK
2399	def_bool $(cc-option,-mfunction-return=thunk-extern)
2400
2401config CC_HAS_ENTRY_PADDING
2402	def_bool $(cc-option,-fpatchable-function-entry=16,16)
2403
2404config CC_HAS_KCFI_ARITY
2405	def_bool $(cc-option,-fsanitize=kcfi -fsanitize-kcfi-arity)
2406	depends on CC_IS_CLANG && !RUST
2407
2408config FUNCTION_PADDING_CFI
2409	int
2410	default 59 if FUNCTION_ALIGNMENT_64B
2411	default 27 if FUNCTION_ALIGNMENT_32B
2412	default 11 if FUNCTION_ALIGNMENT_16B
2413	default  3 if FUNCTION_ALIGNMENT_8B
2414	default  0
2415
2416# Basically: FUNCTION_ALIGNMENT - 5*CFI
2417# except Kconfig can't do arithmetic :/
2418config FUNCTION_PADDING_BYTES
2419	int
2420	default FUNCTION_PADDING_CFI if CFI
2421	default FUNCTION_ALIGNMENT
2422
2423config CALL_PADDING
2424	def_bool n
2425	depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2426	select FUNCTION_ALIGNMENT_16B
2427
2428config FINEIBT
2429	def_bool y
2430	depends on X86_KERNEL_IBT && CFI && MITIGATION_RETPOLINE
2431	select CALL_PADDING
2432
2433config FINEIBT_BHI
2434	def_bool y
2435	depends on FINEIBT && CC_HAS_KCFI_ARITY
2436
2437config HAVE_CALL_THUNKS
2438	def_bool y
2439	depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2440
2441config CALL_THUNKS
2442	def_bool n
2443	select CALL_PADDING
2444
2445config PREFIX_SYMBOLS
2446	def_bool y
2447	depends on CALL_PADDING && !CFI
2448
2449menuconfig CPU_MITIGATIONS
2450	bool "Mitigations for CPU vulnerabilities"
2451	default y
2452	help
2453	  Say Y here to enable options which enable mitigations for hardware
2454	  vulnerabilities (usually related to speculative execution).
2455	  Mitigations can be disabled or restricted to SMT systems at runtime
2456	  via the "mitigations" kernel parameter.
2457
2458	  If you say N, all mitigations will be disabled.  This CANNOT be
2459	  overridden at runtime.
2460
2461	  Say 'Y', unless you really know what you are doing.
2462
2463if CPU_MITIGATIONS
2464
2465config MITIGATION_PAGE_TABLE_ISOLATION
2466	bool "Remove the kernel mapping in user mode"
2467	default y
2468	depends on (X86_64 || X86_PAE)
2469	help
2470	  This feature reduces the number of hardware side channels by
2471	  ensuring that the majority of kernel addresses are not mapped
2472	  into userspace.
2473
2474	  See Documentation/arch/x86/pti.rst for more details.
2475
2476config MITIGATION_RETPOLINE
2477	bool "Avoid speculative indirect branches in kernel"
2478	select OBJTOOL if HAVE_OBJTOOL
2479	default y
2480	help
2481	  Compile kernel with the retpoline compiler options to guard against
2482	  kernel-to-user data leaks by avoiding speculative indirect
2483	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2484	  support for full protection. The kernel may run slower.
2485
2486config MITIGATION_RETHUNK
2487	bool "Enable return-thunks"
2488	depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2489	select OBJTOOL if HAVE_OBJTOOL
2490	default y if X86_64
2491	help
2492	  Compile the kernel with the return-thunks compiler option to guard
2493	  against kernel-to-user data leaks by avoiding return speculation.
2494	  Requires a compiler with -mfunction-return=thunk-extern
2495	  support for full protection. The kernel may run slower.
2496
2497config MITIGATION_UNRET_ENTRY
2498	bool "Enable UNRET on kernel entry"
2499	depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2500	default y
2501	help
2502	  Compile the kernel with support for the retbleed=unret mitigation.
2503
2504config MITIGATION_CALL_DEPTH_TRACKING
2505	bool "Mitigate RSB underflow with call depth tracking"
2506	depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2507	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2508	select CALL_THUNKS
2509	default y
2510	help
2511	  Compile the kernel with call depth tracking to mitigate the Intel
2512	  SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off
2513	  by default and needs to be enabled on the kernel command line via the
2514	  retbleed=stuff option. For non-affected systems the overhead of this
2515	  option is marginal as the call depth tracking is using run-time
2516	  generated call thunks in a compiler generated padding area and call
2517	  patching. This increases text size by ~5%. For non affected systems
2518	  this space is unused. On affected SKL systems this results in a
2519	  significant performance gain over the IBRS mitigation.
2520
2521config CALL_THUNKS_DEBUG
2522	bool "Enable call thunks and call depth tracking debugging"
2523	depends on MITIGATION_CALL_DEPTH_TRACKING
2524	select FUNCTION_ALIGNMENT_32B
2525	default n
2526	help
2527	  Enable call/ret counters for imbalance detection and build in
2528	  a noisy dmesg about callthunks generation and call patching for
2529	  trouble shooting. The debug prints need to be enabled on the
2530	  kernel command line with 'debug-callthunks'.
2531	  Only enable this when you are debugging call thunks as this
2532	  creates a noticeable runtime overhead. If unsure say N.
2533
2534config MITIGATION_IBPB_ENTRY
2535	bool "Enable IBPB on kernel entry"
2536	depends on CPU_SUP_AMD && X86_64
2537	default y
2538	help
2539	  Compile the kernel with support for the retbleed=ibpb and
2540	  spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations.
2541
2542config MITIGATION_IBRS_ENTRY
2543	bool "Enable IBRS on kernel entry"
2544	depends on CPU_SUP_INTEL && X86_64
2545	default y
2546	help
2547	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2548	  This mitigates both spectre_v2 and retbleed at great cost to
2549	  performance.
2550
2551config MITIGATION_SRSO
2552	bool "Mitigate speculative RAS overflow on AMD"
2553	depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2554	default y
2555	help
2556	  Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2557
2558config MITIGATION_SLS
2559	bool "Mitigate Straight-Line-Speculation"
2560	depends on CC_HAS_SLS && X86_64
2561	select OBJTOOL if HAVE_OBJTOOL
2562	default n
2563	help
2564	  Compile the kernel with straight-line-speculation options to guard
2565	  against straight line speculation. The kernel image might be slightly
2566	  larger.
2567
2568config MITIGATION_GDS
2569	bool "Mitigate Gather Data Sampling"
2570	depends on CPU_SUP_INTEL
2571	default y
2572	help
2573	  Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
2574	  vulnerability which allows unprivileged speculative access to data
2575	  which was previously stored in vector registers. The attacker uses gather
2576	  instructions to infer the stale vector register data.
2577
2578config MITIGATION_RFDS
2579	bool "RFDS Mitigation"
2580	depends on CPU_SUP_INTEL
2581	default y
2582	help
2583	  Enable mitigation for Register File Data Sampling (RFDS) by default.
2584	  RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2585	  allows unprivileged speculative access to stale data previously
2586	  stored in floating point, vector and integer registers.
2587	  See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2588
2589config MITIGATION_SPECTRE_BHI
2590	bool "Mitigate Spectre-BHB (Branch History Injection)"
2591	depends on CPU_SUP_INTEL
2592	default y
2593	help
2594	  Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2595	  where the branch history buffer is poisoned to speculatively steer
2596	  indirect branches.
2597	  See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2598
2599config MITIGATION_MDS
2600	bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
2601	depends on CPU_SUP_INTEL
2602	default y
2603	help
2604	  Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
2605	  a hardware vulnerability which allows unprivileged speculative access
2606	  to data which is available in various CPU internal buffers.
2607	  See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
2608
2609config MITIGATION_TAA
2610	bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
2611	depends on CPU_SUP_INTEL
2612	default y
2613	help
2614	  Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
2615	  vulnerability that allows unprivileged speculative access to data
2616	  which is available in various CPU internal buffers by using
2617	  asynchronous aborts within an Intel TSX transactional region.
2618	  See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
2619
2620config MITIGATION_MMIO_STALE_DATA
2621	bool "Mitigate MMIO Stale Data hardware bug"
2622	depends on CPU_SUP_INTEL
2623	default y
2624	help
2625	  Enable mitigation for MMIO Stale Data hardware bugs.  Processor MMIO
2626	  Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
2627	  vulnerabilities that can expose data. The vulnerabilities require the
2628	  attacker to have access to MMIO.
2629	  See also
2630	  <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
2631
2632config MITIGATION_L1TF
2633	bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
2634	depends on CPU_SUP_INTEL
2635	default y
2636	help
2637	  Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
2638	  hardware vulnerability which allows unprivileged speculative access to data
2639	  available in the Level 1 Data Cache.
2640	  See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
2641
2642config MITIGATION_RETBLEED
2643	bool "Mitigate RETBleed hardware bug"
2644	depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
2645	default y
2646	help
2647	  Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
2648	  with Return Instructions) vulnerability.  RETBleed is a speculative
2649	  execution attack which takes advantage of microarchitectural behavior
2650	  in many modern microprocessors, similar to Spectre v2. An
2651	  unprivileged attacker can use these flaws to bypass conventional
2652	  memory security restrictions to gain read access to privileged memory
2653	  that would otherwise be inaccessible.
2654
2655config MITIGATION_SPECTRE_V1
2656	bool "Mitigate SPECTRE V1 hardware bug"
2657	default y
2658	help
2659	  Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
2660	  class of side channel attacks that takes advantage of speculative
2661	  execution that bypasses conditional branch instructions used for
2662	  memory access bounds check.
2663	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2664
2665config MITIGATION_SPECTRE_V2
2666	bool "Mitigate SPECTRE V2 hardware bug"
2667	default y
2668	help
2669	  Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
2670	  V2 is a class of side channel attacks that takes advantage of
2671	  indirect branch predictors inside the processor. In Spectre variant 2
2672	  attacks, the attacker can steer speculative indirect branches in the
2673	  victim to gadget code by poisoning the branch target buffer of a CPU
2674	  used for predicting indirect branch addresses.
2675	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2676
2677config MITIGATION_SRBDS
2678	bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
2679	depends on CPU_SUP_INTEL
2680	default y
2681	help
2682	  Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
2683	  SRBDS is a hardware vulnerability that allows Microarchitectural Data
2684	  Sampling (MDS) techniques to infer values returned from special
2685	  register accesses. An unprivileged user can extract values returned
2686	  from RDRAND and RDSEED executed on another core or sibling thread
2687	  using MDS techniques.
2688	  See also
2689	  <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
2690
2691config MITIGATION_SSB
2692	bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
2693	default y
2694	help
2695	  Enable mitigation for Speculative Store Bypass (SSB). SSB is a
2696	  hardware security vulnerability and its exploitation takes advantage
2697	  of speculative execution in a similar way to the Meltdown and Spectre
2698	  security vulnerabilities.
2699
2700config MITIGATION_ITS
2701	bool "Enable Indirect Target Selection mitigation"
2702	depends on CPU_SUP_INTEL && X86_64
2703	depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK
2704	select EXECMEM
2705	default y
2706	help
2707	  Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in
2708	  BPU on some Intel CPUs that may allow Spectre V2 style attacks. If
2709	  disabled, mitigation cannot be enabled via cmdline.
2710	  See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst>
2711
2712config MITIGATION_TSA
2713	bool "Mitigate Transient Scheduler Attacks"
2714	depends on CPU_SUP_AMD
2715	default y
2716	help
2717	  Enable mitigation for Transient Scheduler Attacks. TSA is a hardware
2718	  security vulnerability on AMD CPUs which can lead to forwarding of
2719	  invalid info to subsequent instructions and thus can affect their
2720	  timing and thereby cause a leakage.
2721
2722config MITIGATION_VMSCAPE
2723	bool "Mitigate VMSCAPE"
2724	depends on KVM
2725	default y
2726	help
2727	  Enable mitigation for VMSCAPE attacks. VMSCAPE is a hardware security
2728	  vulnerability on Intel and AMD CPUs that may allow a guest to do
2729	  Spectre v2 style attacks on userspace hypervisor.
2730endif
2731
2732config ARCH_HAS_ADD_PAGES
2733	def_bool y
2734	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2735
2736menu "Power management and ACPI options"
2737
2738config ARCH_HIBERNATION_HEADER
2739	def_bool y
2740	depends on HIBERNATION
2741
2742source "kernel/power/Kconfig"
2743
2744source "drivers/acpi/Kconfig"
2745
2746config X86_APM_BOOT
2747	def_bool y
2748	depends on APM
2749
2750menuconfig APM
2751	tristate "APM (Advanced Power Management) BIOS support"
2752	depends on X86_32 && PM_SLEEP
2753	help
2754	  APM is a BIOS specification for saving power using several different
2755	  techniques. This is mostly useful for battery powered laptops with
2756	  APM compliant BIOSes. If you say Y here, the system time will be
2757	  reset after a RESUME operation, the /proc/apm device will provide
2758	  battery status information, and user-space programs will receive
2759	  notification of APM "events" (e.g. battery status change).
2760
2761	  If you select "Y" here, you can disable actual use of the APM
2762	  BIOS by passing the "apm=off" option to the kernel at boot time.
2763
2764	  Note that the APM support is almost completely disabled for
2765	  machines with more than one CPU.
2766
2767	  In order to use APM, you will need supporting software. For location
2768	  and more information, read <file:Documentation/power/apm-acpi.rst>
2769	  and the Battery Powered Linux mini-HOWTO, available from
2770	  <http://www.tldp.org/docs.html#howto>.
2771
2772	  This driver does not spin down disk drives (see the hdparm(8)
2773	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2774	  VESA-compliant "green" monitors.
2775
2776	  This driver does not support the TI 4000M TravelMate and the ACER
2777	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2778	  desktop machines also don't have compliant BIOSes, and this driver
2779	  may cause those machines to panic during the boot phase.
2780
2781	  Generally, if you don't have a battery in your machine, there isn't
2782	  much point in using this driver and you should say N. If you get
2783	  random kernel OOPSes or reboots that don't seem to be related to
2784	  anything, try disabling/enabling this option (or disabling/enabling
2785	  APM in your BIOS).
2786
2787	  Some other things you should try when experiencing seemingly random,
2788	  "weird" problems:
2789
2790	  1) make sure that you have enough swap space and that it is
2791	  enabled.
2792	  2) pass the "idle=poll" option to the kernel
2793	  3) switch on floating point emulation in the kernel and pass
2794	  the "no387" option to the kernel
2795	  4) pass the "floppy=nodma" option to the kernel
2796	  5) pass the "mem=4M" option to the kernel (thereby disabling
2797	  all but the first 4 MB of RAM)
2798	  6) make sure that the CPU is not over clocked.
2799	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2800	  8) disable the cache from your BIOS settings
2801	  9) install a fan for the video card or exchange video RAM
2802	  10) install a better fan for the CPU
2803	  11) exchange RAM chips
2804	  12) exchange the motherboard.
2805
2806	  To compile this driver as a module, choose M here: the
2807	  module will be called apm.
2808
2809if APM
2810
2811config APM_IGNORE_USER_SUSPEND
2812	bool "Ignore USER SUSPEND"
2813	help
2814	  This option will ignore USER SUSPEND requests. On machines with a
2815	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2816	  series notebooks, it is necessary to say Y because of a BIOS bug.
2817
2818config APM_DO_ENABLE
2819	bool "Enable PM at boot time"
2820	help
2821	  Enable APM features at boot time. From page 36 of the APM BIOS
2822	  specification: "When disabled, the APM BIOS does not automatically
2823	  power manage devices, enter the Standby State, enter the Suspend
2824	  State, or take power saving steps in response to CPU Idle calls."
2825	  This driver will make CPU Idle calls when Linux is idle (unless this
2826	  feature is turned off -- see "Do CPU IDLE calls", below). This
2827	  should always save battery power, but more complicated APM features
2828	  will be dependent on your BIOS implementation. You may need to turn
2829	  this option off if your computer hangs at boot time when using APM
2830	  support, or if it beeps continuously instead of suspending. Turn
2831	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2832	  T400CDT. This is off by default since most machines do fine without
2833	  this feature.
2834
2835config APM_CPU_IDLE
2836	depends on CPU_IDLE
2837	bool "Make CPU Idle calls when idle"
2838	help
2839	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2840	  On some machines, this can activate improved power savings, such as
2841	  a slowed CPU clock rate, when the machine is idle. These idle calls
2842	  are made after the idle loop has run for some length of time (e.g.,
2843	  333 mS). On some machines, this will cause a hang at boot time or
2844	  whenever the CPU becomes idle. (On machines with more than one CPU,
2845	  this option does nothing.)
2846
2847config APM_DISPLAY_BLANK
2848	bool "Enable console blanking using APM"
2849	help
2850	  Enable console blanking using the APM. Some laptops can use this to
2851	  turn off the LCD backlight when the screen blanker of the Linux
2852	  virtual console blanks the screen. Note that this is only used by
2853	  the virtual console screen blanker, and won't turn off the backlight
2854	  when using the X Window system. This also doesn't have anything to
2855	  do with your VESA-compliant power-saving monitor. Further, this
2856	  option doesn't work for all laptops -- it might not turn off your
2857	  backlight at all, or it might print a lot of errors to the console,
2858	  especially if you are using gpm.
2859
2860config APM_ALLOW_INTS
2861	bool "Allow interrupts during APM BIOS calls"
2862	help
2863	  Normally we disable external interrupts while we are making calls to
2864	  the APM BIOS as a measure to lessen the effects of a badly behaving
2865	  BIOS implementation.  The BIOS should reenable interrupts if it
2866	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2867	  many of the newer IBM Thinkpads.  If you experience hangs when you
2868	  suspend, try setting this to Y.  Otherwise, say N.
2869
2870endif # APM
2871
2872source "drivers/cpufreq/Kconfig"
2873
2874source "drivers/cpuidle/Kconfig"
2875
2876source "drivers/idle/Kconfig"
2877
2878endmenu
2879
2880menu "Bus options (PCI etc.)"
2881
2882choice
2883	prompt "PCI access mode"
2884	depends on X86_32 && PCI
2885	default PCI_GOANY
2886	help
2887	  On PCI systems, the BIOS can be used to detect the PCI devices and
2888	  determine their configuration. However, some old PCI motherboards
2889	  have BIOS bugs and may crash if this is done. Also, some embedded
2890	  PCI-based systems don't have any BIOS at all. Linux can also try to
2891	  detect the PCI hardware directly without using the BIOS.
2892
2893	  With this option, you can specify how Linux should detect the
2894	  PCI devices. If you choose "BIOS", the BIOS will be used,
2895	  if you choose "Direct", the BIOS won't be used, and if you
2896	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2897	  If you choose "Any", the kernel will try MMCONFIG, then the
2898	  direct access method and falls back to the BIOS if that doesn't
2899	  work. If unsure, go with the default, which is "Any".
2900
2901config PCI_GOBIOS
2902	bool "BIOS"
2903
2904config PCI_GOMMCONFIG
2905	bool "MMConfig"
2906
2907config PCI_GODIRECT
2908	bool "Direct"
2909
2910config PCI_GOOLPC
2911	bool "OLPC XO-1"
2912	depends on OLPC
2913
2914config PCI_GOANY
2915	bool "Any"
2916
2917endchoice
2918
2919config PCI_BIOS
2920	def_bool y
2921	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2922
2923# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2924config PCI_DIRECT
2925	def_bool y
2926	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2927
2928config PCI_MMCONFIG
2929	bool "Support mmconfig PCI config space access" if X86_64
2930	default y
2931	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2932	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2933	help
2934	  Add support for accessing the PCI configuration space as a memory
2935	  mapped area. It is the recommended method if the system supports
2936	  this (it must have PCI Express and ACPI for it to be available).
2937
2938	  In the unlikely case that enabling this configuration option causes
2939	  problems, the mechanism can be switched off with the 'pci=nommconf'
2940	  command line parameter.
2941
2942	  Say N only if you are sure that your platform does not support this
2943	  access method or you have problems caused by it.
2944
2945	  Say Y otherwise.
2946
2947config PCI_OLPC
2948	def_bool y
2949	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2950
2951config PCI_XEN
2952	def_bool y
2953	depends on PCI && XEN
2954
2955config MMCONF_FAM10H
2956	def_bool y
2957	depends on X86_64 && PCI_MMCONFIG && ACPI
2958
2959config PCI_CNB20LE_QUIRK
2960	bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT
2961	depends on X86_32 && PCI
2962	help
2963	  Read the PCI windows out of the CNB20LE host bridge. This allows
2964	  PCI hotplug to work on systems with the CNB20LE chipset which do
2965	  not have ACPI.
2966
2967	  The ServerWorks (later Broadcom) CNB20LE was a chipset designed
2968	  most probably only for Pentium III.
2969
2970	  To find out if you have such a chipset, search for a PCI device with
2971	  1166:0009 PCI IDs, for example by executing
2972		lspci -nn | grep '1166:0009'
2973	  The code is inactive if there is none.
2974
2975	  There's no public spec for this chipset, and this functionality
2976	  is known to be incomplete.
2977
2978	  You should say N unless you know you need this.
2979
2980config ISA_BUS
2981	bool "ISA bus support on modern systems" if EXPERT
2982	help
2983	  Expose ISA bus device drivers and options available for selection and
2984	  configuration. Enable this option if your target machine has an ISA
2985	  bus. ISA is an older system, displaced by PCI and newer bus
2986	  architectures -- if your target machine is modern, it probably does
2987	  not have an ISA bus.
2988
2989	  If unsure, say N.
2990
2991# x86_64 have no ISA slots, but can have ISA-style DMA.
2992config ISA_DMA_API
2993	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2994	default y
2995	help
2996	  Enables ISA-style DMA support for devices requiring such controllers.
2997	  If unsure, say Y.
2998
2999if X86_32
3000
3001config ISA
3002	bool "ISA support"
3003	help
3004	  Find out whether you have ISA slots on your motherboard.  ISA is the
3005	  name of a bus system, i.e. the way the CPU talks to the other stuff
3006	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
3007	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
3008	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
3009
3010config SCx200
3011	tristate "NatSemi SCx200 support"
3012	help
3013	  This provides basic support for National Semiconductor's
3014	  (now AMD's) Geode processors.  The driver probes for the
3015	  PCI-IDs of several on-chip devices, so its a good dependency
3016	  for other scx200_* drivers.
3017
3018	  If compiled as a module, the driver is named scx200.
3019
3020config SCx200HR_TIMER
3021	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
3022	depends on SCx200
3023	default y
3024	help
3025	  This driver provides a clocksource built upon the on-chip
3026	  27MHz high-resolution timer.  Its also a workaround for
3027	  NSC Geode SC-1100's buggy TSC, which loses time when the
3028	  processor goes idle (as is done by the scheduler).  The
3029	  other workaround is idle=poll boot option.
3030
3031config OLPC
3032	bool "One Laptop Per Child support"
3033	depends on !X86_PAE
3034	select GPIOLIB
3035	select OF
3036	select OF_PROMTREE
3037	select IRQ_DOMAIN
3038	select OLPC_EC
3039	help
3040	  Add support for detecting the unique features of the OLPC
3041	  XO hardware.
3042
3043config OLPC_XO1_PM
3044	bool "OLPC XO-1 Power Management"
3045	depends on OLPC && MFD_CS5535=y && PM_SLEEP
3046	help
3047	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
3048
3049config OLPC_XO1_RTC
3050	bool "OLPC XO-1 Real Time Clock"
3051	depends on OLPC_XO1_PM && RTC_DRV_CMOS
3052	help
3053	  Add support for the XO-1 real time clock, which can be used as a
3054	  programmable wakeup source.
3055
3056config OLPC_XO1_SCI
3057	bool "OLPC XO-1 SCI extras"
3058	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
3059	depends on INPUT=y
3060	select POWER_SUPPLY
3061	help
3062	  Add support for SCI-based features of the OLPC XO-1 laptop:
3063	   - EC-driven system wakeups
3064	   - Power button
3065	   - Ebook switch
3066	   - Lid switch
3067	   - AC adapter status updates
3068	   - Battery status updates
3069
3070config OLPC_XO15_SCI
3071	bool "OLPC XO-1.5 SCI extras"
3072	depends on OLPC && ACPI
3073	select POWER_SUPPLY
3074	help
3075	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
3076	   - EC-driven system wakeups
3077	   - AC adapter status updates
3078	   - Battery status updates
3079
3080config GEODE_COMMON
3081	bool
3082
3083config ALIX
3084	bool "PCEngines ALIX System Support (LED setup)"
3085	select GPIOLIB
3086	select GEODE_COMMON
3087	help
3088	  This option enables system support for the PCEngines ALIX.
3089	  At present this just sets up LEDs for GPIO control on
3090	  ALIX2/3/6 boards.  However, other system specific setup should
3091	  get added here.
3092
3093	  Note: You must still enable the drivers for GPIO and LED support
3094	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
3095
3096	  Note: You have to set alix.force=1 for boards with Award BIOS.
3097
3098config NET5501
3099	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
3100	select GPIOLIB
3101	select GEODE_COMMON
3102	help
3103	  This option enables system support for the Soekris Engineering net5501.
3104
3105config GEOS
3106	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
3107	select GPIOLIB
3108	select GEODE_COMMON
3109	depends on DMI
3110	help
3111	  This option enables system support for the Traverse Technologies GEOS.
3112
3113config TS5500
3114	bool "Technologic Systems TS-5500 platform support"
3115	depends on MELAN
3116	select CHECK_SIGNATURE
3117	select NEW_LEDS
3118	select LEDS_CLASS
3119	help
3120	  This option enables system support for the Technologic Systems TS-5500.
3121
3122endif # X86_32
3123
3124config AMD_NB
3125	def_bool y
3126	depends on AMD_NODE
3127
3128config AMD_NODE
3129	def_bool y
3130	depends on CPU_SUP_AMD && PCI
3131
3132endmenu
3133
3134menu "Binary Emulations"
3135
3136config IA32_EMULATION
3137	bool "IA32 Emulation"
3138	depends on X86_64
3139	select ARCH_WANT_OLD_COMPAT_IPC
3140	select BINFMT_ELF
3141	select COMPAT_OLD_SIGACTION
3142	help
3143	  Include code to run legacy 32-bit programs under a
3144	  64-bit kernel. You should likely turn this on, unless you're
3145	  100% sure that you don't have any 32-bit programs left.
3146
3147config IA32_EMULATION_DEFAULT_DISABLED
3148	bool "IA32 emulation disabled by default"
3149	default n
3150	depends on IA32_EMULATION
3151	help
3152	  Make IA32 emulation disabled by default. This prevents loading 32-bit
3153	  processes and access to 32-bit syscalls. If unsure, leave it to its
3154	  default value.
3155
3156config X86_X32_ABI
3157	bool "x32 ABI for 64-bit mode"
3158	depends on X86_64
3159	# llvm-objcopy does not convert x86_64 .note.gnu.property or
3160	# compressed debug sections to x86_x32 properly:
3161	# https://github.com/ClangBuiltLinux/linux/issues/514
3162	# https://github.com/ClangBuiltLinux/linux/issues/1141
3163	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3164	help
3165	  Include code to run binaries for the x32 native 32-bit ABI
3166	  for 64-bit processors.  An x32 process gets access to the
3167	  full 64-bit register file and wide data path while leaving
3168	  pointers at 32 bits for smaller memory footprint.
3169
3170config COMPAT_32
3171	def_bool y
3172	depends on IA32_EMULATION || X86_32
3173	select HAVE_UID16
3174	select OLD_SIGSUSPEND3
3175
3176config COMPAT
3177	def_bool y
3178	depends on IA32_EMULATION || X86_X32_ABI
3179
3180config COMPAT_FOR_U64_ALIGNMENT
3181	def_bool y
3182	depends on COMPAT
3183
3184endmenu
3185
3186config HAVE_ATOMIC_IOMAP
3187	def_bool y
3188	depends on X86_32
3189
3190source "arch/x86/kvm/Kconfig"
3191
3192source "arch/x86/Kconfig.cpufeatures"
3193
3194source "arch/x86/Kconfig.assembler"
3195