• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1# SPDX-License-Identifier: GPL-2.0
2# Select 32 or 64 bit
3config 64BIT
4	bool "64-bit kernel" if "$(ARCH)" = "x86"
5	default "$(ARCH)" != "i386"
6	help
7	  Say yes to build a 64-bit kernel - formerly known as x86_64
8	  Say no to build a 32-bit kernel - formerly known as i386
9
10config X86_32
11	def_bool y
12	depends on !64BIT
13	# Options that are inherently 32-bit kernel only:
14	select ARCH_WANT_IPC_PARSE_VERSION
15	select CLKSRC_I8253
16	select CLONE_BACKWARDS
17	select GENERIC_VDSO_32
18	select HAVE_DEBUG_STACKOVERFLOW
19	select KMAP_LOCAL
20	select MODULES_USE_ELF_REL
21	select OLD_SIGACTION
22	select ARCH_SPLIT_ARG64
23
24config X86_64
25	def_bool y
26	depends on 64BIT
27	# Options that are inherently 64-bit kernel only:
28	select ARCH_HAS_GIGANTIC_PAGE
29	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30	select ARCH_SUPPORTS_PER_VMA_LOCK
31	select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
32	select HAVE_ARCH_SOFT_DIRTY
33	select MODULES_USE_ELF_RELA
34	select NEED_DMA_MAP_STATE
35	select SWIOTLB
36	select ARCH_HAS_ELFCORE_COMPAT
37	select ZONE_DMA32
38	select EXECMEM if DYNAMIC_FTRACE
39
40config FORCE_DYNAMIC_FTRACE
41	def_bool y
42	depends on X86_32
43	depends on FUNCTION_TRACER
44	select DYNAMIC_FTRACE
45	help
46	  We keep the static function tracing (!DYNAMIC_FTRACE) around
47	  in order to test the non static function tracing in the
48	  generic code, as other architectures still use it. But we
49	  only need to keep it around for x86_64. No need to keep it
50	  for x86_32. For x86_32, force DYNAMIC_FTRACE.
51#
52# Arch settings
53#
54# ( Note that options that are marked 'if X86_64' could in principle be
55#   ported to 32-bit as well. )
56#
57config X86
58	def_bool y
59	#
60	# Note: keep this list sorted alphabetically
61	#
62	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
63	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
64	select ACPI_HOTPLUG_CPU			if ACPI_PROCESSOR && HOTPLUG_CPU
65	select ARCH_32BIT_OFF_T			if X86_32
66	select ARCH_CLOCKSOURCE_INIT
67	select ARCH_CONFIGURES_CPU_MITIGATIONS
68	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
69	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
70	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
71	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
72	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
73	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
74	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
75	select ARCH_HAS_CACHE_LINE_SIZE
76	select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
77	select ARCH_HAS_CPU_FINALIZE_INIT
78	select ARCH_HAS_CPU_PASID		if IOMMU_SVA
79	select ARCH_HAS_CURRENT_STACK_POINTER
80	select ARCH_HAS_DEBUG_VIRTUAL
81	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
82	select ARCH_HAS_DEVMEM_IS_ALLOWED
83	select ARCH_HAS_DMA_OPS			if GART_IOMMU || XEN
84	select ARCH_HAS_EARLY_DEBUG		if KGDB
85	select ARCH_HAS_ELF_RANDOMIZE
86	select ARCH_HAS_FAST_MULTIPLIER
87	select ARCH_HAS_FORTIFY_SOURCE
88	select ARCH_HAS_GCOV_PROFILE_ALL
89	select ARCH_HAS_KCOV			if X86_64
90	select ARCH_HAS_KERNEL_FPU_SUPPORT
91	select ARCH_HAS_MEM_ENCRYPT
92	select ARCH_HAS_MEMBARRIER_SYNC_CORE
93	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
94	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
95	select ARCH_HAS_PMEM_API		if X86_64
96	select ARCH_HAS_PTE_DEVMAP		if X86_64
97	select ARCH_HAS_PTE_SPECIAL
98	select ARCH_HAS_HW_PTE_YOUNG
99	select ARCH_HAS_NONLEAF_PMD_YOUNG	if PGTABLE_LEVELS > 2
100	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
101	select ARCH_HAS_COPY_MC			if X86_64
102	select ARCH_HAS_SET_MEMORY
103	select ARCH_HAS_SET_DIRECT_MAP
104	select ARCH_HAS_STRICT_KERNEL_RWX
105	select ARCH_HAS_STRICT_MODULE_RWX
106	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
107	select ARCH_HAS_SYSCALL_WRAPPER
108	select ARCH_HAS_UBSAN
109	select ARCH_HAS_DEBUG_WX
110	select ARCH_HAS_ZONE_DMA_SET if EXPERT
111	select ARCH_HAVE_NMI_SAFE_CMPXCHG
112	select ARCH_HAVE_EXTRA_ELF_NOTES
113	select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
114	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
115	select ARCH_MIGHT_HAVE_PC_PARPORT
116	select ARCH_MIGHT_HAVE_PC_SERIO
117	select ARCH_STACKWALK
118	select ARCH_SUPPORTS_ACPI
119	select ARCH_SUPPORTS_ATOMIC_RMW
120	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
121	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
122	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
123	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
124	select ARCH_SUPPORTS_CFI_CLANG		if X86_64
125	select ARCH_USES_CFI_TRAPS		if X86_64 && CFI_CLANG
126	select ARCH_SUPPORTS_LTO_CLANG
127	select ARCH_SUPPORTS_LTO_CLANG_THIN
128	select ARCH_SUPPORTS_RT
129	select ARCH_SUPPORTS_AUTOFDO_CLANG
130	select ARCH_USE_BUILTIN_BSWAP
131	select ARCH_USE_CMPXCHG_LOCKREF		if X86_CMPXCHG64
132	select ARCH_USE_MEMTEST
133	select ARCH_USE_QUEUED_RWLOCKS
134	select ARCH_USE_QUEUED_SPINLOCKS
135	select ARCH_USE_SYM_ANNOTATIONS
136	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
137	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
138	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
139	select ARCH_WANTS_NO_INSTR
140	select ARCH_WANT_GENERAL_HUGETLB
141	select ARCH_WANT_HUGE_PMD_SHARE		if X86_64
142	select ARCH_WANT_LD_ORPHAN_WARN
143	select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP	if X86_64
144	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP	if X86_64
145	select ARCH_WANTS_THP_SWAP		if X86_64
146	select ARCH_HAS_PARANOID_L1D_FLUSH
147	select BUILDTIME_TABLE_SORT
148	select CLKEVT_I8253
149	select CLOCKSOURCE_WATCHDOG
150	# Word-size accesses may read uninitialized data past the trailing \0
151	# in strings and cause false KMSAN reports.
152	select DCACHE_WORD_ACCESS		if !KMSAN
153	select DYNAMIC_SIGFRAME
154	select EDAC_ATOMIC_SCRUB
155	select EDAC_SUPPORT
156	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
157	select GENERIC_CLOCKEVENTS_BROADCAST_IDLE	if GENERIC_CLOCKEVENTS_BROADCAST
158	select GENERIC_CLOCKEVENTS_MIN_ADJUST
159	select GENERIC_CMOS_UPDATE
160	select GENERIC_CPU_AUTOPROBE
161	select GENERIC_CPU_DEVICES
162	select GENERIC_CPU_VULNERABILITIES
163	select GENERIC_EARLY_IOREMAP
164	select GENERIC_ENTRY
165	select GENERIC_IOMAP
166	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
167	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
168	select GENERIC_IRQ_MIGRATION		if SMP
169	select GENERIC_IRQ_PROBE
170	select GENERIC_IRQ_RESERVATION_MODE
171	select GENERIC_IRQ_SHOW
172	select GENERIC_PENDING_IRQ		if SMP
173	select GENERIC_PTDUMP
174	select GENERIC_SMP_IDLE_THREAD
175	select GENERIC_TIME_VSYSCALL
176	select GENERIC_GETTIMEOFDAY
177	select GENERIC_VDSO_TIME_NS
178	select GENERIC_VDSO_OVERFLOW_PROTECT
179	select GUP_GET_PXX_LOW_HIGH		if X86_PAE
180	select HARDIRQS_SW_RESEND
181	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
182	select HAS_IOPORT
183	select HAVE_ACPI_APEI			if ACPI
184	select HAVE_ACPI_APEI_NMI		if ACPI
185	select HAVE_ALIGNED_STRUCT_PAGE
186	select HAVE_ARCH_AUDITSYSCALL
187	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
188	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
189	select HAVE_ARCH_JUMP_LABEL
190	select HAVE_ARCH_JUMP_LABEL_RELATIVE
191	select HAVE_ARCH_KASAN			if X86_64
192	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
193	select HAVE_ARCH_KFENCE
194	select HAVE_ARCH_KMSAN			if X86_64
195	select HAVE_ARCH_KGDB
196	select HAVE_ARCH_MMAP_RND_BITS		if MMU
197	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
198	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
199	select HAVE_ARCH_PREL32_RELOCATIONS
200	select HAVE_ARCH_SECCOMP_FILTER
201	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
202	select HAVE_ARCH_STACKLEAK
203	select HAVE_ARCH_TRACEHOOK
204	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
205	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
206	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
207	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
208	select HAVE_ARCH_VMAP_STACK		if X86_64
209	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
210	select HAVE_ARCH_WITHIN_STACK_FRAMES
211	select HAVE_ASM_MODVERSIONS
212	select HAVE_CMPXCHG_DOUBLE
213	select HAVE_CMPXCHG_LOCAL
214	select HAVE_CONTEXT_TRACKING_USER		if X86_64
215	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
216	select HAVE_C_RECORDMCOUNT
217	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
218	select HAVE_OBJTOOL_NOP_MCOUNT		if HAVE_OBJTOOL_MCOUNT
219	select HAVE_BUILDTIME_MCOUNT_SORT
220	select HAVE_DEBUG_KMEMLEAK
221	select HAVE_DMA_CONTIGUOUS
222	select HAVE_DYNAMIC_FTRACE
223	select HAVE_DYNAMIC_FTRACE_WITH_REGS
224	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
225	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
226	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
227	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
228	select HAVE_EBPF_JIT
229	select HAVE_EFFICIENT_UNALIGNED_ACCESS
230	select HAVE_EISA			if X86_32
231	select HAVE_EXIT_THREAD
232	select HAVE_GUP_FAST
233	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
234	select HAVE_FTRACE_MCOUNT_RECORD
235	select HAVE_FUNCTION_GRAPH_RETVAL	if HAVE_FUNCTION_GRAPH_TRACER
236	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
237	select HAVE_FUNCTION_TRACER
238	select HAVE_GCC_PLUGINS
239	select HAVE_HW_BREAKPOINT
240	select HAVE_IOREMAP_PROT
241	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
242	select HAVE_IRQ_TIME_ACCOUNTING
243	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
244	select HAVE_KERNEL_BZIP2
245	select HAVE_KERNEL_GZIP
246	select HAVE_KERNEL_LZ4
247	select HAVE_KERNEL_LZMA
248	select HAVE_KERNEL_LZO
249	select HAVE_KERNEL_XZ
250	select HAVE_KERNEL_ZSTD
251	select HAVE_KPROBES
252	select HAVE_KPROBES_ON_FTRACE
253	select HAVE_FUNCTION_ERROR_INJECTION
254	select HAVE_KRETPROBES
255	select HAVE_RETHOOK
256	select HAVE_LIVEPATCH			if X86_64
257	select HAVE_MIXED_BREAKPOINTS_REGS
258	select HAVE_MOD_ARCH_SPECIFIC
259	select HAVE_MOVE_PMD
260	select HAVE_MOVE_PUD
261	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
262	select HAVE_NMI
263	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
264	select HAVE_OBJTOOL			if X86_64
265	select HAVE_OPTPROBES
266	select HAVE_PAGE_SIZE_4KB
267	select HAVE_PCSPKR_PLATFORM
268	select HAVE_PERF_EVENTS
269	select HAVE_PERF_EVENTS_NMI
270	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
271	select HAVE_PCI
272	select HAVE_PERF_REGS
273	select HAVE_PERF_USER_STACK_DUMP
274	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
275	select MMU_GATHER_MERGE_VMAS
276	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
277	select HAVE_REGS_AND_STACK_ACCESS_API
278	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
279	select HAVE_FUNCTION_ARG_ACCESS_API
280	select HAVE_SETUP_PER_CPU_AREA
281	select HAVE_SOFTIRQ_ON_OWN_STACK
282	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
283	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
284	select HAVE_STATIC_CALL
285	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
286	select HAVE_PREEMPT_DYNAMIC_CALL
287	select HAVE_RSEQ
288	select HAVE_RUST			if X86_64
289	select HAVE_SYSCALL_TRACEPOINTS
290	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
291	select HAVE_UNSTABLE_SCHED_CLOCK
292	select HAVE_USER_RETURN_NOTIFIER
293	select HAVE_GENERIC_VDSO
294	select VDSO_GETRANDOM			if X86_64
295	select HOTPLUG_PARALLEL			if SMP && X86_64
296	select HOTPLUG_SMT			if SMP
297	select HOTPLUG_SPLIT_STARTUP		if SMP && X86_32
298	select IRQ_FORCED_THREADING
299	select LOCK_MM_AND_FIND_VMA
300	select NEED_PER_CPU_EMBED_FIRST_CHUNK
301	select NEED_PER_CPU_PAGE_FIRST_CHUNK
302	select NEED_SG_DMA_LENGTH
303	select NUMA_MEMBLKS			if NUMA
304	select PCI_DOMAINS			if PCI
305	select PCI_LOCKLESS_CONFIG		if PCI
306	select PERF_EVENTS
307	select RTC_LIB
308	select RTC_MC146818_LIB
309	select SPARSE_IRQ
310	select SYSCTL_EXCEPTION_TRACE
311	select THREAD_INFO_IN_TASK
312	select TRACE_IRQFLAGS_SUPPORT
313	select TRACE_IRQFLAGS_NMI_SUPPORT
314	select USER_STACKTRACE_SUPPORT
315	select HAVE_ARCH_KCSAN			if X86_64
316	select PROC_PID_ARCH_STATUS		if PROC_FS
317	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
318	select FUNCTION_ALIGNMENT_16B		if X86_64 || X86_ALIGNMENT_16
319	select FUNCTION_ALIGNMENT_4B
320	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
321	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
322
323config INSTRUCTION_DECODER
324	def_bool y
325	depends on KPROBES || PERF_EVENTS || UPROBES
326
327config OUTPUT_FORMAT
328	string
329	default "elf32-i386" if X86_32
330	default "elf64-x86-64" if X86_64
331
332config LOCKDEP_SUPPORT
333	def_bool y
334
335config STACKTRACE_SUPPORT
336	def_bool y
337
338config MMU
339	def_bool y
340
341config ARCH_MMAP_RND_BITS_MIN
342	default 28 if 64BIT
343	default 8
344
345config ARCH_MMAP_RND_BITS_MAX
346	default 32 if 64BIT
347	default 16
348
349config ARCH_MMAP_RND_COMPAT_BITS_MIN
350	default 8
351
352config ARCH_MMAP_RND_COMPAT_BITS_MAX
353	default 16
354
355config SBUS
356	bool
357
358config GENERIC_ISA_DMA
359	def_bool y
360	depends on ISA_DMA_API
361
362config GENERIC_CSUM
363	bool
364	default y if KMSAN || KASAN
365
366config GENERIC_BUG
367	def_bool y
368	depends on BUG
369	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
370
371config GENERIC_BUG_RELATIVE_POINTERS
372	bool
373
374config ARCH_MAY_HAVE_PC_FDC
375	def_bool y
376	depends on ISA_DMA_API
377
378config GENERIC_CALIBRATE_DELAY
379	def_bool y
380
381config ARCH_HAS_CPU_RELAX
382	def_bool y
383
384config ARCH_HIBERNATION_POSSIBLE
385	def_bool y
386
387config ARCH_SUSPEND_POSSIBLE
388	def_bool y
389
390config AUDIT_ARCH
391	def_bool y if X86_64
392
393config KASAN_SHADOW_OFFSET
394	hex
395	depends on KASAN
396	default 0xdffffc0000000000
397
398config HAVE_INTEL_TXT
399	def_bool y
400	depends on INTEL_IOMMU && ACPI
401
402config X86_64_SMP
403	def_bool y
404	depends on X86_64 && SMP
405
406config ARCH_SUPPORTS_UPROBES
407	def_bool y
408
409config FIX_EARLYCON_MEM
410	def_bool y
411
412config DYNAMIC_PHYSICAL_MASK
413	bool
414
415config PGTABLE_LEVELS
416	int
417	default 5 if X86_5LEVEL
418	default 4 if X86_64
419	default 3 if X86_PAE
420	default 2
421
422config CC_HAS_SANE_STACKPROTECTOR
423	bool
424	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
425	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
426	help
427	  We have to make sure stack protector is unconditionally disabled if
428	  the compiler produces broken code or if it does not let us control
429	  the segment on 32-bit kernels.
430
431menu "Processor type and features"
432
433config SMP
434	bool "Symmetric multi-processing support"
435	help
436	  This enables support for systems with more than one CPU. If you have
437	  a system with only one CPU, say N. If you have a system with more
438	  than one CPU, say Y.
439
440	  If you say N here, the kernel will run on uni- and multiprocessor
441	  machines, but will use only one CPU of a multiprocessor machine. If
442	  you say Y here, the kernel will run on many, but not all,
443	  uniprocessor machines. On a uniprocessor machine, the kernel
444	  will run faster if you say N here.
445
446	  Note that if you say Y here and choose architecture "586" or
447	  "Pentium" under "Processor family", the kernel will not work on 486
448	  architectures. Similarly, multiprocessor kernels for the "PPro"
449	  architecture may not work on all Pentium based boards.
450
451	  People using multiprocessor machines who say Y here should also say
452	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
453	  Management" code will be disabled if you say Y here.
454
455	  See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
456	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
457	  <http://www.tldp.org/docs.html#howto>.
458
459	  If you don't know what to do here, say N.
460
461config X86_X2APIC
462	bool "Support x2apic"
463	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
464	help
465	  This enables x2apic support on CPUs that have this feature.
466
467	  This allows 32-bit apic IDs (so it can support very large systems),
468	  and accesses the local apic via MSRs not via mmio.
469
470	  Some Intel systems circa 2022 and later are locked into x2APIC mode
471	  and can not fall back to the legacy APIC modes if SGX or TDX are
472	  enabled in the BIOS. They will boot with very reduced functionality
473	  without enabling this option.
474
475	  If you don't know what to do here, say N.
476
477config X86_POSTED_MSI
478	bool "Enable MSI and MSI-x delivery by posted interrupts"
479	depends on X86_64 && IRQ_REMAP
480	help
481	  This enables MSIs that are under interrupt remapping to be delivered as
482	  posted interrupts to the host kernel. Interrupt throughput can
483	  potentially be improved by coalescing CPU notifications during high
484	  frequency bursts.
485
486	  If you don't know what to do here, say N.
487
488config X86_MPPARSE
489	bool "Enable MPS table" if ACPI
490	default y
491	depends on X86_LOCAL_APIC
492	help
493	  For old smp systems that do not have proper acpi support. Newer systems
494	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
495
496config X86_CPU_RESCTRL
497	bool "x86 CPU resource control support"
498	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
499	select KERNFS
500	select PROC_CPU_RESCTRL		if PROC_FS
501	help
502	  Enable x86 CPU resource control support.
503
504	  Provide support for the allocation and monitoring of system resources
505	  usage by the CPU.
506
507	  Intel calls this Intel Resource Director Technology
508	  (Intel(R) RDT). More information about RDT can be found in the
509	  Intel x86 Architecture Software Developer Manual.
510
511	  AMD calls this AMD Platform Quality of Service (AMD QoS).
512	  More information about AMD QoS can be found in the AMD64 Technology
513	  Platform Quality of Service Extensions manual.
514
515	  Say N if unsure.
516
517config X86_FRED
518	bool "Flexible Return and Event Delivery"
519	depends on X86_64
520	help
521	  When enabled, try to use Flexible Return and Event Delivery
522	  instead of the legacy SYSCALL/SYSENTER/IDT architecture for
523	  ring transitions and exception/interrupt handling if the
524	  system supports it.
525
526config X86_BIGSMP
527	bool "Support for big SMP systems with more than 8 CPUs"
528	depends on SMP && X86_32
529	help
530	  This option is needed for the systems that have more than 8 CPUs.
531
532config X86_EXTENDED_PLATFORM
533	bool "Support for extended (non-PC) x86 platforms"
534	default y
535	help
536	  If you disable this option then the kernel will only support
537	  standard PC platforms. (which covers the vast majority of
538	  systems out there.)
539
540	  If you enable this option then you'll be able to select support
541	  for the following non-PC x86 platforms, depending on the value of
542	  CONFIG_64BIT.
543
544	  32-bit platforms (CONFIG_64BIT=n):
545		Goldfish (Android emulator)
546		AMD Elan
547		RDC R-321x SoC
548		SGI 320/540 (Visual Workstation)
549		STA2X11-based (e.g. Northville)
550		Moorestown MID devices
551
552	  64-bit platforms (CONFIG_64BIT=y):
553		Numascale NumaChip
554		ScaleMP vSMP
555		SGI Ultraviolet
556
557	  If you have one of these systems, or if you want to build a
558	  generic distribution kernel, say Y here - otherwise say N.
559
560# This is an alphabetically sorted list of 64 bit extended platforms
561# Please maintain the alphabetic order if and when there are additions
562config X86_NUMACHIP
563	bool "Numascale NumaChip"
564	depends on X86_64
565	depends on X86_EXTENDED_PLATFORM
566	depends on NUMA
567	depends on SMP
568	depends on X86_X2APIC
569	depends on PCI_MMCONFIG
570	help
571	  Adds support for Numascale NumaChip large-SMP systems. Needed to
572	  enable more than ~168 cores.
573	  If you don't have one of these, you should say N here.
574
575config X86_VSMP
576	bool "ScaleMP vSMP"
577	select HYPERVISOR_GUEST
578	select PARAVIRT
579	depends on X86_64 && PCI
580	depends on X86_EXTENDED_PLATFORM
581	depends on SMP
582	help
583	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
584	  supposed to run on these EM64T-based machines.  Only choose this option
585	  if you have one of these machines.
586
587config X86_UV
588	bool "SGI Ultraviolet"
589	depends on X86_64
590	depends on X86_EXTENDED_PLATFORM
591	depends on NUMA
592	depends on EFI
593	depends on KEXEC_CORE
594	depends on X86_X2APIC
595	depends on PCI
596	help
597	  This option is needed in order to support SGI Ultraviolet systems.
598	  If you don't have one of these, you should say N here.
599
600# Following is an alphabetically sorted list of 32 bit extended platforms
601# Please maintain the alphabetic order if and when there are additions
602
603config X86_GOLDFISH
604	bool "Goldfish (Virtual Platform)"
605	depends on X86_EXTENDED_PLATFORM
606	help
607	  Enable support for the Goldfish virtual platform used primarily
608	  for Android development. Unless you are building for the Android
609	  Goldfish emulator say N here.
610
611config X86_INTEL_CE
612	bool "CE4100 TV platform"
613	depends on PCI
614	depends on PCI_GODIRECT
615	depends on X86_IO_APIC
616	depends on X86_32
617	depends on X86_EXTENDED_PLATFORM
618	select X86_REBOOTFIXUPS
619	select OF
620	select OF_EARLY_FLATTREE
621	help
622	  Select for the Intel CE media processor (CE4100) SOC.
623	  This option compiles in support for the CE4100 SOC for settop
624	  boxes and media devices.
625
626config X86_INTEL_MID
627	bool "Intel MID platform support"
628	depends on X86_EXTENDED_PLATFORM
629	depends on X86_PLATFORM_DEVICES
630	depends on PCI
631	depends on X86_64 || (PCI_GOANY && X86_32)
632	depends on X86_IO_APIC
633	select I2C
634	select DW_APB_TIMER
635	select INTEL_SCU_PCI
636	help
637	  Select to build a kernel capable of supporting Intel MID (Mobile
638	  Internet Device) platform systems which do not have the PCI legacy
639	  interfaces. If you are building for a PC class system say N here.
640
641	  Intel MID platforms are based on an Intel processor and chipset which
642	  consume less power than most of the x86 derivatives.
643
644config X86_INTEL_QUARK
645	bool "Intel Quark platform support"
646	depends on X86_32
647	depends on X86_EXTENDED_PLATFORM
648	depends on X86_PLATFORM_DEVICES
649	depends on X86_TSC
650	depends on PCI
651	depends on PCI_GOANY
652	depends on X86_IO_APIC
653	select IOSF_MBI
654	select INTEL_IMR
655	select COMMON_CLK
656	help
657	  Select to include support for Quark X1000 SoC.
658	  Say Y here if you have a Quark based system such as the Arduino
659	  compatible Intel Galileo.
660
661config X86_INTEL_LPSS
662	bool "Intel Low Power Subsystem Support"
663	depends on X86 && ACPI && PCI
664	select COMMON_CLK
665	select PINCTRL
666	select IOSF_MBI
667	help
668	  Select to build support for Intel Low Power Subsystem such as
669	  found on Intel Lynxpoint PCH. Selecting this option enables
670	  things like clock tree (common clock framework) and pincontrol
671	  which are needed by the LPSS peripheral drivers.
672
673config X86_AMD_PLATFORM_DEVICE
674	bool "AMD ACPI2Platform devices support"
675	depends on ACPI
676	select COMMON_CLK
677	select PINCTRL
678	help
679	  Select to interpret AMD specific ACPI device to platform device
680	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
681	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
682	  implemented under PINCTRL subsystem.
683
684config IOSF_MBI
685	tristate "Intel SoC IOSF Sideband support for SoC platforms"
686	depends on PCI
687	help
688	  This option enables sideband register access support for Intel SoC
689	  platforms. On these platforms the IOSF sideband is used in lieu of
690	  MSR's for some register accesses, mostly but not limited to thermal
691	  and power. Drivers may query the availability of this device to
692	  determine if they need the sideband in order to work on these
693	  platforms. The sideband is available on the following SoC products.
694	  This list is not meant to be exclusive.
695	   - BayTrail
696	   - Braswell
697	   - Quark
698
699	  You should say Y if you are running a kernel on one of these SoC's.
700
701config IOSF_MBI_DEBUG
702	bool "Enable IOSF sideband access through debugfs"
703	depends on IOSF_MBI && DEBUG_FS
704	help
705	  Select this option to expose the IOSF sideband access registers (MCR,
706	  MDR, MCRX) through debugfs to write and read register information from
707	  different units on the SoC. This is most useful for obtaining device
708	  state information for debug and analysis. As this is a general access
709	  mechanism, users of this option would have specific knowledge of the
710	  device they want to access.
711
712	  If you don't require the option or are in doubt, say N.
713
714config X86_RDC321X
715	bool "RDC R-321x SoC"
716	depends on X86_32
717	depends on X86_EXTENDED_PLATFORM
718	select M486
719	select X86_REBOOTFIXUPS
720	help
721	  This option is needed for RDC R-321x system-on-chip, also known
722	  as R-8610-(G).
723	  If you don't have one of these chips, you should say N here.
724
725config X86_32_NON_STANDARD
726	bool "Support non-standard 32-bit SMP architectures"
727	depends on X86_32 && SMP
728	depends on X86_EXTENDED_PLATFORM
729	help
730	  This option compiles in the bigsmp and STA2X11 default
731	  subarchitectures.  It is intended for a generic binary
732	  kernel. If you select them all, kernel will probe it one by
733	  one and will fallback to default.
734
735# Alphabetically sorted list of Non standard 32 bit platforms
736
737config X86_SUPPORTS_MEMORY_FAILURE
738	def_bool y
739	# MCE code calls memory_failure():
740	depends on X86_MCE
741	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
742	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
743	depends on X86_64 || !SPARSEMEM
744	select ARCH_SUPPORTS_MEMORY_FAILURE
745
746config STA2X11
747	bool "STA2X11 Companion Chip Support"
748	depends on X86_32_NON_STANDARD && PCI
749	select SWIOTLB
750	select MFD_STA2X11
751	select GPIOLIB
752	help
753	  This adds support for boards based on the STA2X11 IO-Hub,
754	  a.k.a. "ConneXt". The chip is used in place of the standard
755	  PC chipset, so all "standard" peripherals are missing. If this
756	  option is selected the kernel will still be able to boot on
757	  standard PC machines.
758
759config X86_32_IRIS
760	tristate "Eurobraille/Iris poweroff module"
761	depends on X86_32
762	help
763	  The Iris machines from EuroBraille do not have APM or ACPI support
764	  to shut themselves down properly.  A special I/O sequence is
765	  needed to do so, which is what this module does at
766	  kernel shutdown.
767
768	  This is only for Iris machines from EuroBraille.
769
770	  If unused, say N.
771
772config SCHED_OMIT_FRAME_POINTER
773	def_bool y
774	prompt "Single-depth WCHAN output"
775	depends on X86
776	help
777	  Calculate simpler /proc/<PID>/wchan values. If this option
778	  is disabled then wchan values will recurse back to the
779	  caller function. This provides more accurate wchan values,
780	  at the expense of slightly more scheduling overhead.
781
782	  If in doubt, say "Y".
783
784menuconfig HYPERVISOR_GUEST
785	bool "Linux guest support"
786	help
787	  Say Y here to enable options for running Linux under various hyper-
788	  visors. This option enables basic hypervisor detection and platform
789	  setup.
790
791	  If you say N, all options in this submenu will be skipped and
792	  disabled, and Linux guest support won't be built in.
793
794if HYPERVISOR_GUEST
795
796config PARAVIRT
797	bool "Enable paravirtualization code"
798	depends on HAVE_STATIC_CALL
799	help
800	  This changes the kernel so it can modify itself when it is run
801	  under a hypervisor, potentially improving performance significantly
802	  over full virtualization.  However, when run without a hypervisor
803	  the kernel is theoretically slower and slightly larger.
804
805config PARAVIRT_XXL
806	bool
807
808config PARAVIRT_DEBUG
809	bool "paravirt-ops debugging"
810	depends on PARAVIRT && DEBUG_KERNEL
811	help
812	  Enable to debug paravirt_ops internals.  Specifically, BUG if
813	  a paravirt_op is missing when it is called.
814
815config PARAVIRT_SPINLOCKS
816	bool "Paravirtualization layer for spinlocks"
817	depends on PARAVIRT && SMP
818	help
819	  Paravirtualized spinlocks allow a pvops backend to replace the
820	  spinlock implementation with something virtualization-friendly
821	  (for example, block the virtual CPU rather than spinning).
822
823	  It has a minimal impact on native kernels and gives a nice performance
824	  benefit on paravirtualized KVM / Xen kernels.
825
826	  If you are unsure how to answer this question, answer Y.
827
828config X86_HV_CALLBACK_VECTOR
829	def_bool n
830
831source "arch/x86/xen/Kconfig"
832
833config KVM_GUEST
834	bool "KVM Guest support (including kvmclock)"
835	depends on PARAVIRT
836	select PARAVIRT_CLOCK
837	select ARCH_CPUIDLE_HALTPOLL
838	select X86_HV_CALLBACK_VECTOR
839	default y
840	help
841	  This option enables various optimizations for running under the KVM
842	  hypervisor. It includes a paravirtualized clock, so that instead
843	  of relying on a PIT (or probably other) emulation by the
844	  underlying device model, the host provides the guest with
845	  timing infrastructure such as time of day, and system time
846
847config ARCH_CPUIDLE_HALTPOLL
848	def_bool n
849	prompt "Disable host haltpoll when loading haltpoll driver"
850	help
851	  If virtualized under KVM, disable host haltpoll.
852
853config PVH
854	bool "Support for running PVH guests"
855	help
856	  This option enables the PVH entry point for guest virtual machines
857	  as specified in the x86/HVM direct boot ABI.
858
859config PARAVIRT_TIME_ACCOUNTING
860	bool "Paravirtual steal time accounting"
861	depends on PARAVIRT
862	help
863	  Select this option to enable fine granularity task steal time
864	  accounting. Time spent executing other tasks in parallel with
865	  the current vCPU is discounted from the vCPU power. To account for
866	  that, there can be a small performance impact.
867
868	  If in doubt, say N here.
869
870config PARAVIRT_CLOCK
871	bool
872
873config JAILHOUSE_GUEST
874	bool "Jailhouse non-root cell support"
875	depends on X86_64 && PCI
876	select X86_PM_TIMER
877	help
878	  This option allows to run Linux as guest in a Jailhouse non-root
879	  cell. You can leave this option disabled if you only want to start
880	  Jailhouse and run Linux afterwards in the root cell.
881
882config ACRN_GUEST
883	bool "ACRN Guest support"
884	depends on X86_64
885	select X86_HV_CALLBACK_VECTOR
886	help
887	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
888	  a flexible, lightweight reference open-source hypervisor, built with
889	  real-time and safety-criticality in mind. It is built for embedded
890	  IOT with small footprint and real-time features. More details can be
891	  found in https://projectacrn.org/.
892
893config INTEL_TDX_GUEST
894	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
895	depends on X86_64 && CPU_SUP_INTEL
896	depends on X86_X2APIC
897	depends on EFI_STUB
898	depends on PARAVIRT
899	select ARCH_HAS_CC_PLATFORM
900	select X86_MEM_ENCRYPT
901	select X86_MCE
902	select UNACCEPTED_MEMORY
903	help
904	  Support running as a guest under Intel TDX.  Without this support,
905	  the guest kernel can not boot or run under TDX.
906	  TDX includes memory encryption and integrity capabilities
907	  which protect the confidentiality and integrity of guest
908	  memory contents and CPU state. TDX guests are protected from
909	  some attacks from the VMM.
910
911endif # HYPERVISOR_GUEST
912
913source "arch/x86/Kconfig.cpu"
914
915config HPET_TIMER
916	def_bool X86_64
917	prompt "HPET Timer Support" if X86_32
918	help
919	  Use the IA-PC HPET (High Precision Event Timer) to manage
920	  time in preference to the PIT and RTC, if a HPET is
921	  present.
922	  HPET is the next generation timer replacing legacy 8254s.
923	  The HPET provides a stable time base on SMP
924	  systems, unlike the TSC, but it is more expensive to access,
925	  as it is off-chip.  The interface used is documented
926	  in the HPET spec, revision 1.
927
928	  You can safely choose Y here.  However, HPET will only be
929	  activated if the platform and the BIOS support this feature.
930	  Otherwise the 8254 will be used for timing services.
931
932	  Choose N to continue using the legacy 8254 timer.
933
934config HPET_EMULATE_RTC
935	def_bool y
936	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
937
938# Mark as expert because too many people got it wrong.
939# The code disables itself when not needed.
940config DMI
941	default y
942	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
943	bool "Enable DMI scanning" if EXPERT
944	help
945	  Enabled scanning of DMI to identify machine quirks. Say Y
946	  here unless you have verified that your setup is not
947	  affected by entries in the DMI blacklist. Required by PNP
948	  BIOS code.
949
950config GART_IOMMU
951	bool "Old AMD GART IOMMU support"
952	select IOMMU_HELPER
953	select SWIOTLB
954	depends on X86_64 && PCI && AMD_NB
955	help
956	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
957	  GART based hardware IOMMUs.
958
959	  The GART supports full DMA access for devices with 32-bit access
960	  limitations, on systems with more than 3 GB. This is usually needed
961	  for USB, sound, many IDE/SATA chipsets and some other devices.
962
963	  Newer systems typically have a modern AMD IOMMU, supported via
964	  the CONFIG_AMD_IOMMU=y config option.
965
966	  In normal configurations this driver is only active when needed:
967	  there's more than 3 GB of memory and the system contains a
968	  32-bit limited device.
969
970	  If unsure, say Y.
971
972config BOOT_VESA_SUPPORT
973	bool
974	help
975	  If true, at least one selected framebuffer driver can take advantage
976	  of VESA video modes set at an early boot stage via the vga= parameter.
977
978config MAXSMP
979	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
980	depends on X86_64 && SMP && DEBUG_KERNEL
981	select CPUMASK_OFFSTACK
982	help
983	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
984	  If unsure, say N.
985
986#
987# The maximum number of CPUs supported:
988#
989# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
990# and which can be configured interactively in the
991# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
992#
993# The ranges are different on 32-bit and 64-bit kernels, depending on
994# hardware capabilities and scalability features of the kernel.
995#
996# ( If MAXSMP is enabled we just use the highest possible value and disable
997#   interactive configuration. )
998#
999
1000config NR_CPUS_RANGE_BEGIN
1001	int
1002	default NR_CPUS_RANGE_END if MAXSMP
1003	default    1 if !SMP
1004	default    2
1005
1006config NR_CPUS_RANGE_END
1007	int
1008	depends on X86_32
1009	default   64 if  SMP &&  X86_BIGSMP
1010	default    8 if  SMP && !X86_BIGSMP
1011	default    1 if !SMP
1012
1013config NR_CPUS_RANGE_END
1014	int
1015	depends on X86_64
1016	default 8192 if  SMP && CPUMASK_OFFSTACK
1017	default  512 if  SMP && !CPUMASK_OFFSTACK
1018	default    1 if !SMP
1019
1020config NR_CPUS_DEFAULT
1021	int
1022	depends on X86_32
1023	default   32 if  X86_BIGSMP
1024	default    8 if  SMP
1025	default    1 if !SMP
1026
1027config NR_CPUS_DEFAULT
1028	int
1029	depends on X86_64
1030	default 8192 if  MAXSMP
1031	default   64 if  SMP
1032	default    1 if !SMP
1033
1034config NR_CPUS
1035	int "Maximum number of CPUs" if SMP && !MAXSMP
1036	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1037	default NR_CPUS_DEFAULT
1038	help
1039	  This allows you to specify the maximum number of CPUs which this
1040	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1041	  supported value is 8192, otherwise the maximum value is 512.  The
1042	  minimum value which makes sense is 2.
1043
1044	  This is purely to save memory: each supported CPU adds about 8KB
1045	  to the kernel image.
1046
1047config SCHED_CLUSTER
1048	bool "Cluster scheduler support"
1049	depends on SMP
1050	default y
1051	help
1052	  Cluster scheduler support improves the CPU scheduler's decision
1053	  making when dealing with machines that have clusters of CPUs.
1054	  Cluster usually means a couple of CPUs which are placed closely
1055	  by sharing mid-level caches, last-level cache tags or internal
1056	  busses.
1057
1058config SCHED_SMT
1059	def_bool y if SMP
1060
1061config SCHED_MC
1062	def_bool y
1063	prompt "Multi-core scheduler support"
1064	depends on SMP
1065	help
1066	  Multi-core scheduler support improves the CPU scheduler's decision
1067	  making when dealing with multi-core CPU chips at a cost of slightly
1068	  increased overhead in some places. If unsure say N here.
1069
1070config SCHED_MC_PRIO
1071	bool "CPU core priorities scheduler support"
1072	depends on SCHED_MC
1073	select X86_INTEL_PSTATE if CPU_SUP_INTEL
1074	select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
1075	select CPU_FREQ
1076	default y
1077	help
1078	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1079	  core ordering determined at manufacturing time, which allows
1080	  certain cores to reach higher turbo frequencies (when running
1081	  single threaded workloads) than others.
1082
1083	  Enabling this kernel feature teaches the scheduler about
1084	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1085	  scheduler's CPU selection logic accordingly, so that higher
1086	  overall system performance can be achieved.
1087
1088	  This feature will have no effect on CPUs without this feature.
1089
1090	  If unsure say Y here.
1091
1092config UP_LATE_INIT
1093	def_bool y
1094	depends on !SMP && X86_LOCAL_APIC
1095
1096config X86_UP_APIC
1097	bool "Local APIC support on uniprocessors" if !PCI_MSI
1098	default PCI_MSI
1099	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1100	help
1101	  A local APIC (Advanced Programmable Interrupt Controller) is an
1102	  integrated interrupt controller in the CPU. If you have a single-CPU
1103	  system which has a processor with a local APIC, you can say Y here to
1104	  enable and use it. If you say Y here even though your machine doesn't
1105	  have a local APIC, then the kernel will still run with no slowdown at
1106	  all. The local APIC supports CPU-generated self-interrupts (timer,
1107	  performance counters), and the NMI watchdog which detects hard
1108	  lockups.
1109
1110config X86_UP_IOAPIC
1111	bool "IO-APIC support on uniprocessors"
1112	depends on X86_UP_APIC
1113	help
1114	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1115	  SMP-capable replacement for PC-style interrupt controllers. Most
1116	  SMP systems and many recent uniprocessor systems have one.
1117
1118	  If you have a single-CPU system with an IO-APIC, you can say Y here
1119	  to use it. If you say Y here even though your machine doesn't have
1120	  an IO-APIC, then the kernel will still run with no slowdown at all.
1121
1122config X86_LOCAL_APIC
1123	def_bool y
1124	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1125	select IRQ_DOMAIN_HIERARCHY
1126
1127config ACPI_MADT_WAKEUP
1128	def_bool y
1129	depends on X86_64
1130	depends on ACPI
1131	depends on SMP
1132	depends on X86_LOCAL_APIC
1133
1134config X86_IO_APIC
1135	def_bool y
1136	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1137
1138config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1139	bool "Reroute for broken boot IRQs"
1140	depends on X86_IO_APIC
1141	help
1142	  This option enables a workaround that fixes a source of
1143	  spurious interrupts. This is recommended when threaded
1144	  interrupt handling is used on systems where the generation of
1145	  superfluous "boot interrupts" cannot be disabled.
1146
1147	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1148	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1149	  kernel does during interrupt handling). On chipsets where this
1150	  boot IRQ generation cannot be disabled, this workaround keeps
1151	  the original IRQ line masked so that only the equivalent "boot
1152	  IRQ" is delivered to the CPUs. The workaround also tells the
1153	  kernel to set up the IRQ handler on the boot IRQ line. In this
1154	  way only one interrupt is delivered to the kernel. Otherwise
1155	  the spurious second interrupt may cause the kernel to bring
1156	  down (vital) interrupt lines.
1157
1158	  Only affects "broken" chipsets. Interrupt sharing may be
1159	  increased on these systems.
1160
1161config X86_MCE
1162	bool "Machine Check / overheating reporting"
1163	select GENERIC_ALLOCATOR
1164	default y
1165	help
1166	  Machine Check support allows the processor to notify the
1167	  kernel if it detects a problem (e.g. overheating, data corruption).
1168	  The action the kernel takes depends on the severity of the problem,
1169	  ranging from warning messages to halting the machine.
1170
1171config X86_MCELOG_LEGACY
1172	bool "Support for deprecated /dev/mcelog character device"
1173	depends on X86_MCE
1174	help
1175	  Enable support for /dev/mcelog which is needed by the old mcelog
1176	  userspace logging daemon. Consider switching to the new generation
1177	  rasdaemon solution.
1178
1179config X86_MCE_INTEL
1180	def_bool y
1181	prompt "Intel MCE features"
1182	depends on X86_MCE && X86_LOCAL_APIC
1183	help
1184	  Additional support for intel specific MCE features such as
1185	  the thermal monitor.
1186
1187config X86_MCE_AMD
1188	def_bool y
1189	prompt "AMD MCE features"
1190	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1191	help
1192	  Additional support for AMD specific MCE features such as
1193	  the DRAM Error Threshold.
1194
1195config X86_ANCIENT_MCE
1196	bool "Support for old Pentium 5 / WinChip machine checks"
1197	depends on X86_32 && X86_MCE
1198	help
1199	  Include support for machine check handling on old Pentium 5 or WinChip
1200	  systems. These typically need to be enabled explicitly on the command
1201	  line.
1202
1203config X86_MCE_THRESHOLD
1204	depends on X86_MCE_AMD || X86_MCE_INTEL
1205	def_bool y
1206
1207config X86_MCE_INJECT
1208	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1209	tristate "Machine check injector support"
1210	help
1211	  Provide support for injecting machine checks for testing purposes.
1212	  If you don't know what a machine check is and you don't do kernel
1213	  QA it is safe to say n.
1214
1215source "arch/x86/events/Kconfig"
1216
1217config X86_LEGACY_VM86
1218	bool "Legacy VM86 support"
1219	depends on X86_32
1220	help
1221	  This option allows user programs to put the CPU into V8086
1222	  mode, which is an 80286-era approximation of 16-bit real mode.
1223
1224	  Some very old versions of X and/or vbetool require this option
1225	  for user mode setting.  Similarly, DOSEMU will use it if
1226	  available to accelerate real mode DOS programs.  However, any
1227	  recent version of DOSEMU, X, or vbetool should be fully
1228	  functional even without kernel VM86 support, as they will all
1229	  fall back to software emulation. Nevertheless, if you are using
1230	  a 16-bit DOS program where 16-bit performance matters, vm86
1231	  mode might be faster than emulation and you might want to
1232	  enable this option.
1233
1234	  Note that any app that works on a 64-bit kernel is unlikely to
1235	  need this option, as 64-bit kernels don't, and can't, support
1236	  V8086 mode. This option is also unrelated to 16-bit protected
1237	  mode and is not needed to run most 16-bit programs under Wine.
1238
1239	  Enabling this option increases the complexity of the kernel
1240	  and slows down exception handling a tiny bit.
1241
1242	  If unsure, say N here.
1243
1244config VM86
1245	bool
1246	default X86_LEGACY_VM86
1247
1248config X86_16BIT
1249	bool "Enable support for 16-bit segments" if EXPERT
1250	default y
1251	depends on MODIFY_LDT_SYSCALL
1252	help
1253	  This option is required by programs like Wine to run 16-bit
1254	  protected mode legacy code on x86 processors.  Disabling
1255	  this option saves about 300 bytes on i386, or around 6K text
1256	  plus 16K runtime memory on x86-64,
1257
1258config X86_ESPFIX32
1259	def_bool y
1260	depends on X86_16BIT && X86_32
1261
1262config X86_ESPFIX64
1263	def_bool y
1264	depends on X86_16BIT && X86_64
1265
1266config X86_VSYSCALL_EMULATION
1267	bool "Enable vsyscall emulation" if EXPERT
1268	default y
1269	depends on X86_64
1270	help
1271	  This enables emulation of the legacy vsyscall page.  Disabling
1272	  it is roughly equivalent to booting with vsyscall=none, except
1273	  that it will also disable the helpful warning if a program
1274	  tries to use a vsyscall.  With this option set to N, offending
1275	  programs will just segfault, citing addresses of the form
1276	  0xffffffffff600?00.
1277
1278	  This option is required by many programs built before 2013, and
1279	  care should be used even with newer programs if set to N.
1280
1281	  Disabling this option saves about 7K of kernel size and
1282	  possibly 4K of additional runtime pagetable memory.
1283
1284config X86_IOPL_IOPERM
1285	bool "IOPERM and IOPL Emulation"
1286	default y
1287	help
1288	  This enables the ioperm() and iopl() syscalls which are necessary
1289	  for legacy applications.
1290
1291	  Legacy IOPL support is an overbroad mechanism which allows user
1292	  space aside of accessing all 65536 I/O ports also to disable
1293	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1294	  capabilities and permission from potentially active security
1295	  modules.
1296
1297	  The emulation restricts the functionality of the syscall to
1298	  only allowing the full range I/O port access, but prevents the
1299	  ability to disable interrupts from user space which would be
1300	  granted if the hardware IOPL mechanism would be used.
1301
1302config TOSHIBA
1303	tristate "Toshiba Laptop support"
1304	depends on X86_32
1305	help
1306	  This adds a driver to safely access the System Management Mode of
1307	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1308	  not work on models with a Phoenix BIOS. The System Management Mode
1309	  is used to set the BIOS and power saving options on Toshiba portables.
1310
1311	  For information on utilities to make use of this driver see the
1312	  Toshiba Linux utilities web site at:
1313	  <http://www.buzzard.org.uk/toshiba/>.
1314
1315	  Say Y if you intend to run this kernel on a Toshiba portable.
1316	  Say N otherwise.
1317
1318config X86_REBOOTFIXUPS
1319	bool "Enable X86 board specific fixups for reboot"
1320	depends on X86_32
1321	help
1322	  This enables chipset and/or board specific fixups to be done
1323	  in order to get reboot to work correctly. This is only needed on
1324	  some combinations of hardware and BIOS. The symptom, for which
1325	  this config is intended, is when reboot ends with a stalled/hung
1326	  system.
1327
1328	  Currently, the only fixup is for the Geode machines using
1329	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1330
1331	  Say Y if you want to enable the fixup. Currently, it's safe to
1332	  enable this option even if you don't need it.
1333	  Say N otherwise.
1334
1335config MICROCODE
1336	def_bool y
1337	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1338	select CRYPTO_LIB_SHA256 if CPU_SUP_AMD
1339
1340config MICROCODE_INITRD32
1341	def_bool y
1342	depends on MICROCODE && X86_32 && BLK_DEV_INITRD
1343
1344config MICROCODE_LATE_LOADING
1345	bool "Late microcode loading (DANGEROUS)"
1346	default n
1347	depends on MICROCODE && SMP
1348	help
1349	  Loading microcode late, when the system is up and executing instructions
1350	  is a tricky business and should be avoided if possible. Just the sequence
1351	  of synchronizing all cores and SMT threads is one fragile dance which does
1352	  not guarantee that cores might not softlock after the loading. Therefore,
1353	  use this at your own risk. Late loading taints the kernel unless the
1354	  microcode header indicates that it is safe for late loading via the
1355	  minimal revision check. This minimal revision check can be enforced on
1356	  the kernel command line with "microcode.minrev=Y".
1357
1358config MICROCODE_LATE_FORCE_MINREV
1359	bool "Enforce late microcode loading minimal revision check"
1360	default n
1361	depends on MICROCODE_LATE_LOADING
1362	help
1363	  To prevent that users load microcode late which modifies already
1364	  in use features, newer microcode patches have a minimum revision field
1365	  in the microcode header, which tells the kernel which minimum
1366	  revision must be active in the CPU to safely load that new microcode
1367	  late into the running system. If disabled the check will not
1368	  be enforced but the kernel will be tainted when the minimal
1369	  revision check fails.
1370
1371	  This minimal revision check can also be controlled via the
1372	  "microcode.minrev" parameter on the kernel command line.
1373
1374	  If unsure say Y.
1375
1376config X86_MSR
1377	tristate "/dev/cpu/*/msr - Model-specific register support"
1378	help
1379	  This device gives privileged processes access to the x86
1380	  Model-Specific Registers (MSRs).  It is a character device with
1381	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1382	  MSR accesses are directed to a specific CPU on multi-processor
1383	  systems.
1384
1385config X86_CPUID
1386	tristate "/dev/cpu/*/cpuid - CPU information support"
1387	help
1388	  This device gives processes access to the x86 CPUID instruction to
1389	  be executed on a specific processor.  It is a character device
1390	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1391	  /dev/cpu/31/cpuid.
1392
1393choice
1394	prompt "High Memory Support"
1395	default HIGHMEM4G
1396	depends on X86_32
1397
1398config NOHIGHMEM
1399	bool "off"
1400	help
1401	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1402	  However, the address space of 32-bit x86 processors is only 4
1403	  Gigabytes large. That means that, if you have a large amount of
1404	  physical memory, not all of it can be "permanently mapped" by the
1405	  kernel. The physical memory that's not permanently mapped is called
1406	  "high memory".
1407
1408	  If you are compiling a kernel which will never run on a machine with
1409	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1410	  choice and suitable for most users). This will result in a "3GB/1GB"
1411	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1412	  space and the remaining part of the 4GB virtual memory space is used
1413	  by the kernel to permanently map as much physical memory as
1414	  possible.
1415
1416	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1417	  answer "4GB" here.
1418
1419	  If more than 4 Gigabytes is used then answer "64GB" here. This
1420	  selection turns Intel PAE (Physical Address Extension) mode on.
1421	  PAE implements 3-level paging on IA32 processors. PAE is fully
1422	  supported by Linux, PAE mode is implemented on all recent Intel
1423	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1424	  then the kernel will not boot on CPUs that don't support PAE!
1425
1426	  The actual amount of total physical memory will either be
1427	  auto detected or can be forced by using a kernel command line option
1428	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1429	  your boot loader (lilo or loadlin) about how to pass options to the
1430	  kernel at boot time.)
1431
1432	  If unsure, say "off".
1433
1434config HIGHMEM4G
1435	bool "4GB"
1436	help
1437	  Select this if you have a 32-bit processor and between 1 and 4
1438	  gigabytes of physical RAM.
1439
1440config HIGHMEM64G
1441	bool "64GB"
1442	depends on X86_HAVE_PAE
1443	select X86_PAE
1444	help
1445	  Select this if you have a 32-bit processor and more than 4
1446	  gigabytes of physical RAM.
1447
1448endchoice
1449
1450choice
1451	prompt "Memory split" if EXPERT
1452	default VMSPLIT_3G
1453	depends on X86_32
1454	help
1455	  Select the desired split between kernel and user memory.
1456
1457	  If the address range available to the kernel is less than the
1458	  physical memory installed, the remaining memory will be available
1459	  as "high memory". Accessing high memory is a little more costly
1460	  than low memory, as it needs to be mapped into the kernel first.
1461	  Note that increasing the kernel address space limits the range
1462	  available to user programs, making the address space there
1463	  tighter.  Selecting anything other than the default 3G/1G split
1464	  will also likely make your kernel incompatible with binary-only
1465	  kernel modules.
1466
1467	  If you are not absolutely sure what you are doing, leave this
1468	  option alone!
1469
1470	config VMSPLIT_3G
1471		bool "3G/1G user/kernel split"
1472	config VMSPLIT_3G_OPT
1473		depends on !X86_PAE
1474		bool "3G/1G user/kernel split (for full 1G low memory)"
1475	config VMSPLIT_2G
1476		bool "2G/2G user/kernel split"
1477	config VMSPLIT_2G_OPT
1478		depends on !X86_PAE
1479		bool "2G/2G user/kernel split (for full 2G low memory)"
1480	config VMSPLIT_1G
1481		bool "1G/3G user/kernel split"
1482endchoice
1483
1484config PAGE_OFFSET
1485	hex
1486	default 0xB0000000 if VMSPLIT_3G_OPT
1487	default 0x80000000 if VMSPLIT_2G
1488	default 0x78000000 if VMSPLIT_2G_OPT
1489	default 0x40000000 if VMSPLIT_1G
1490	default 0xC0000000
1491	depends on X86_32
1492
1493config HIGHMEM
1494	def_bool y
1495	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1496
1497config X86_PAE
1498	bool "PAE (Physical Address Extension) Support"
1499	depends on X86_32 && X86_HAVE_PAE
1500	select PHYS_ADDR_T_64BIT
1501	select SWIOTLB
1502	help
1503	  PAE is required for NX support, and furthermore enables
1504	  larger swapspace support for non-overcommit purposes. It
1505	  has the cost of more pagetable lookup overhead, and also
1506	  consumes more pagetable space per process.
1507
1508config X86_5LEVEL
1509	bool "Enable 5-level page tables support"
1510	default y
1511	select DYNAMIC_MEMORY_LAYOUT
1512	select SPARSEMEM_VMEMMAP
1513	depends on X86_64
1514	help
1515	  5-level paging enables access to larger address space:
1516	  up to 128 PiB of virtual address space and 4 PiB of
1517	  physical address space.
1518
1519	  It will be supported by future Intel CPUs.
1520
1521	  A kernel with the option enabled can be booted on machines that
1522	  support 4- or 5-level paging.
1523
1524	  See Documentation/arch/x86/x86_64/5level-paging.rst for more
1525	  information.
1526
1527	  Say N if unsure.
1528
1529config X86_DIRECT_GBPAGES
1530	def_bool y
1531	depends on X86_64
1532	help
1533	  Certain kernel features effectively disable kernel
1534	  linear 1 GB mappings (even if the CPU otherwise
1535	  supports them), so don't confuse the user by printing
1536	  that we have them enabled.
1537
1538config X86_CPA_STATISTICS
1539	bool "Enable statistic for Change Page Attribute"
1540	depends on DEBUG_FS
1541	help
1542	  Expose statistics about the Change Page Attribute mechanism, which
1543	  helps to determine the effectiveness of preserving large and huge
1544	  page mappings when mapping protections are changed.
1545
1546config X86_MEM_ENCRYPT
1547	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1548	select DYNAMIC_PHYSICAL_MASK
1549	def_bool n
1550
1551config AMD_MEM_ENCRYPT
1552	bool "AMD Secure Memory Encryption (SME) support"
1553	depends on X86_64 && CPU_SUP_AMD
1554	depends on EFI_STUB
1555	select DMA_COHERENT_POOL
1556	select ARCH_USE_MEMREMAP_PROT
1557	select INSTRUCTION_DECODER
1558	select ARCH_HAS_CC_PLATFORM
1559	select X86_MEM_ENCRYPT
1560	select UNACCEPTED_MEMORY
1561	help
1562	  Say yes to enable support for the encryption of system memory.
1563	  This requires an AMD processor that supports Secure Memory
1564	  Encryption (SME).
1565
1566# Common NUMA Features
1567config NUMA
1568	bool "NUMA Memory Allocation and Scheduler Support"
1569	depends on SMP
1570	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1571	default y if X86_BIGSMP
1572	select USE_PERCPU_NUMA_NODE_ID
1573	select OF_NUMA if OF
1574	help
1575	  Enable NUMA (Non-Uniform Memory Access) support.
1576
1577	  The kernel will try to allocate memory used by a CPU on the
1578	  local memory controller of the CPU and add some more
1579	  NUMA awareness to the kernel.
1580
1581	  For 64-bit this is recommended if the system is Intel Core i7
1582	  (or later), AMD Opteron, or EM64T NUMA.
1583
1584	  For 32-bit this is only needed if you boot a 32-bit
1585	  kernel on a 64-bit NUMA platform.
1586
1587	  Otherwise, you should say N.
1588
1589config AMD_NUMA
1590	def_bool y
1591	prompt "Old style AMD Opteron NUMA detection"
1592	depends on X86_64 && NUMA && PCI
1593	help
1594	  Enable AMD NUMA node topology detection.  You should say Y here if
1595	  you have a multi processor AMD system. This uses an old method to
1596	  read the NUMA configuration directly from the builtin Northbridge
1597	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1598	  which also takes priority if both are compiled in.
1599
1600config X86_64_ACPI_NUMA
1601	def_bool y
1602	prompt "ACPI NUMA detection"
1603	depends on X86_64 && NUMA && ACPI && PCI
1604	select ACPI_NUMA
1605	help
1606	  Enable ACPI SRAT based node topology detection.
1607
1608config NODES_SHIFT
1609	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1610	range 1 10
1611	default "10" if MAXSMP
1612	default "6" if X86_64
1613	default "3"
1614	depends on NUMA
1615	help
1616	  Specify the maximum number of NUMA Nodes available on the target
1617	  system.  Increases memory reserved to accommodate various tables.
1618
1619config ARCH_FLATMEM_ENABLE
1620	def_bool y
1621	depends on X86_32 && !NUMA
1622
1623config ARCH_SPARSEMEM_ENABLE
1624	def_bool y
1625	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1626	select SPARSEMEM_STATIC if X86_32
1627	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1628
1629config ARCH_SPARSEMEM_DEFAULT
1630	def_bool X86_64 || (NUMA && X86_32)
1631
1632config ARCH_SELECT_MEMORY_MODEL
1633	def_bool y
1634	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1635
1636config ARCH_MEMORY_PROBE
1637	bool "Enable sysfs memory/probe interface"
1638	depends on MEMORY_HOTPLUG
1639	help
1640	  This option enables a sysfs memory/probe interface for testing.
1641	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1642	  If you are unsure how to answer this question, answer N.
1643
1644config ARCH_PROC_KCORE_TEXT
1645	def_bool y
1646	depends on X86_64 && PROC_KCORE
1647
1648config ILLEGAL_POINTER_VALUE
1649	hex
1650	default 0 if X86_32
1651	default 0xdead000000000000 if X86_64
1652
1653config X86_PMEM_LEGACY_DEVICE
1654	bool
1655
1656config X86_PMEM_LEGACY
1657	tristate "Support non-standard NVDIMMs and ADR protected memory"
1658	depends on PHYS_ADDR_T_64BIT
1659	depends on BLK_DEV
1660	select X86_PMEM_LEGACY_DEVICE
1661	select NUMA_KEEP_MEMINFO if NUMA
1662	select LIBNVDIMM
1663	help
1664	  Treat memory marked using the non-standard e820 type of 12 as used
1665	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1666	  The kernel will offer these regions to the 'pmem' driver so
1667	  they can be used for persistent storage.
1668
1669	  Say Y if unsure.
1670
1671config HIGHPTE
1672	bool "Allocate 3rd-level pagetables from highmem"
1673	depends on HIGHMEM
1674	help
1675	  The VM uses one page table entry for each page of physical memory.
1676	  For systems with a lot of RAM, this can be wasteful of precious
1677	  low memory.  Setting this option will put user-space page table
1678	  entries in high memory.
1679
1680config X86_CHECK_BIOS_CORRUPTION
1681	bool "Check for low memory corruption"
1682	help
1683	  Periodically check for memory corruption in low memory, which
1684	  is suspected to be caused by BIOS.  Even when enabled in the
1685	  configuration, it is disabled at runtime.  Enable it by
1686	  setting "memory_corruption_check=1" on the kernel command
1687	  line.  By default it scans the low 64k of memory every 60
1688	  seconds; see the memory_corruption_check_size and
1689	  memory_corruption_check_period parameters in
1690	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1691
1692	  When enabled with the default parameters, this option has
1693	  almost no overhead, as it reserves a relatively small amount
1694	  of memory and scans it infrequently.  It both detects corruption
1695	  and prevents it from affecting the running system.
1696
1697	  It is, however, intended as a diagnostic tool; if repeatable
1698	  BIOS-originated corruption always affects the same memory,
1699	  you can use memmap= to prevent the kernel from using that
1700	  memory.
1701
1702config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1703	bool "Set the default setting of memory_corruption_check"
1704	depends on X86_CHECK_BIOS_CORRUPTION
1705	default y
1706	help
1707	  Set whether the default state of memory_corruption_check is
1708	  on or off.
1709
1710config MATH_EMULATION
1711	bool
1712	depends on MODIFY_LDT_SYSCALL
1713	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1714	help
1715	  Linux can emulate a math coprocessor (used for floating point
1716	  operations) if you don't have one. 486DX and Pentium processors have
1717	  a math coprocessor built in, 486SX and 386 do not, unless you added
1718	  a 487DX or 387, respectively. (The messages during boot time can
1719	  give you some hints here ["man dmesg"].) Everyone needs either a
1720	  coprocessor or this emulation.
1721
1722	  If you don't have a math coprocessor, you need to say Y here; if you
1723	  say Y here even though you have a coprocessor, the coprocessor will
1724	  be used nevertheless. (This behavior can be changed with the kernel
1725	  command line option "no387", which comes handy if your coprocessor
1726	  is broken. Try "man bootparam" or see the documentation of your boot
1727	  loader (lilo or loadlin) about how to pass options to the kernel at
1728	  boot time.) This means that it is a good idea to say Y here if you
1729	  intend to use this kernel on different machines.
1730
1731	  More information about the internals of the Linux math coprocessor
1732	  emulation can be found in <file:arch/x86/math-emu/README>.
1733
1734	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1735	  kernel, it won't hurt.
1736
1737config MTRR
1738	def_bool y
1739	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1740	help
1741	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1742	  the Memory Type Range Registers (MTRRs) may be used to control
1743	  processor access to memory ranges. This is most useful if you have
1744	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1745	  allows bus write transfers to be combined into a larger transfer
1746	  before bursting over the PCI/AGP bus. This can increase performance
1747	  of image write operations 2.5 times or more. Saying Y here creates a
1748	  /proc/mtrr file which may be used to manipulate your processor's
1749	  MTRRs. Typically the X server should use this.
1750
1751	  This code has a reasonably generic interface so that similar
1752	  control registers on other processors can be easily supported
1753	  as well:
1754
1755	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1756	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1757	  these, the ARRs are used to emulate the MTRRs.
1758	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1759	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1760	  write-combining. All of these processors are supported by this code
1761	  and it makes sense to say Y here if you have one of them.
1762
1763	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1764	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1765	  can lead to all sorts of problems, so it's good to say Y here.
1766
1767	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1768	  just add about 9 KB to your kernel.
1769
1770	  See <file:Documentation/arch/x86/mtrr.rst> for more information.
1771
1772config MTRR_SANITIZER
1773	def_bool y
1774	prompt "MTRR cleanup support"
1775	depends on MTRR
1776	help
1777	  Convert MTRR layout from continuous to discrete, so X drivers can
1778	  add writeback entries.
1779
1780	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1781	  The largest mtrr entry size for a continuous block can be set with
1782	  mtrr_chunk_size.
1783
1784	  If unsure, say Y.
1785
1786config MTRR_SANITIZER_ENABLE_DEFAULT
1787	int "MTRR cleanup enable value (0-1)"
1788	range 0 1
1789	default "0"
1790	depends on MTRR_SANITIZER
1791	help
1792	  Enable mtrr cleanup default value
1793
1794config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1795	int "MTRR cleanup spare reg num (0-7)"
1796	range 0 7
1797	default "1"
1798	depends on MTRR_SANITIZER
1799	help
1800	  mtrr cleanup spare entries default, it can be changed via
1801	  mtrr_spare_reg_nr=N on the kernel command line.
1802
1803config X86_PAT
1804	def_bool y
1805	prompt "x86 PAT support" if EXPERT
1806	depends on MTRR
1807	select ARCH_USES_PG_ARCH_2
1808	help
1809	  Use PAT attributes to setup page level cache control.
1810
1811	  PATs are the modern equivalents of MTRRs and are much more
1812	  flexible than MTRRs.
1813
1814	  Say N here if you see bootup problems (boot crash, boot hang,
1815	  spontaneous reboots) or a non-working video driver.
1816
1817	  If unsure, say Y.
1818
1819config X86_UMIP
1820	def_bool y
1821	prompt "User Mode Instruction Prevention" if EXPERT
1822	help
1823	  User Mode Instruction Prevention (UMIP) is a security feature in
1824	  some x86 processors. If enabled, a general protection fault is
1825	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1826	  executed in user mode. These instructions unnecessarily expose
1827	  information about the hardware state.
1828
1829	  The vast majority of applications do not use these instructions.
1830	  For the very few that do, software emulation is provided in
1831	  specific cases in protected and virtual-8086 modes. Emulated
1832	  results are dummy.
1833
1834config CC_HAS_IBT
1835	# GCC >= 9 and binutils >= 2.29
1836	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1837	# Clang/LLVM >= 14
1838	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1839	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1840	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1841		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1842		  $(as-instr,endbr64)
1843
1844config X86_CET
1845	def_bool n
1846	help
1847	  CET features configured (Shadow stack or IBT)
1848
1849config X86_KERNEL_IBT
1850	prompt "Indirect Branch Tracking"
1851	def_bool y
1852	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1853	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1854	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1855	select OBJTOOL
1856	select X86_CET
1857	help
1858	  Build the kernel with support for Indirect Branch Tracking, a
1859	  hardware support course-grain forward-edge Control Flow Integrity
1860	  protection. It enforces that all indirect calls must land on
1861	  an ENDBR instruction, as such, the compiler will instrument the
1862	  code with them to make this happen.
1863
1864	  In addition to building the kernel with IBT, seal all functions that
1865	  are not indirect call targets, avoiding them ever becoming one.
1866
1867	  This requires LTO like objtool runs and will slow down the build. It
1868	  does significantly reduce the number of ENDBR instructions in the
1869	  kernel image.
1870
1871config X86_INTEL_MEMORY_PROTECTION_KEYS
1872	prompt "Memory Protection Keys"
1873	def_bool y
1874	# Note: only available in 64-bit mode
1875	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1876	select ARCH_USES_HIGH_VMA_FLAGS
1877	select ARCH_HAS_PKEYS
1878	help
1879	  Memory Protection Keys provides a mechanism for enforcing
1880	  page-based protections, but without requiring modification of the
1881	  page tables when an application changes protection domains.
1882
1883	  For details, see Documentation/core-api/protection-keys.rst
1884
1885	  If unsure, say y.
1886
1887config ARCH_PKEY_BITS
1888	int
1889	default 4
1890
1891choice
1892	prompt "TSX enable mode"
1893	depends on CPU_SUP_INTEL
1894	default X86_INTEL_TSX_MODE_OFF
1895	help
1896	  Intel's TSX (Transactional Synchronization Extensions) feature
1897	  allows to optimize locking protocols through lock elision which
1898	  can lead to a noticeable performance boost.
1899
1900	  On the other hand it has been shown that TSX can be exploited
1901	  to form side channel attacks (e.g. TAA) and chances are there
1902	  will be more of those attacks discovered in the future.
1903
1904	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1905	  might override this decision by tsx=on the command line parameter.
1906	  Even with TSX enabled, the kernel will attempt to enable the best
1907	  possible TAA mitigation setting depending on the microcode available
1908	  for the particular machine.
1909
1910	  This option allows to set the default tsx mode between tsx=on, =off
1911	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1912	  details.
1913
1914	  Say off if not sure, auto if TSX is in use but it should be used on safe
1915	  platforms or on if TSX is in use and the security aspect of tsx is not
1916	  relevant.
1917
1918config X86_INTEL_TSX_MODE_OFF
1919	bool "off"
1920	help
1921	  TSX is disabled if possible - equals to tsx=off command line parameter.
1922
1923config X86_INTEL_TSX_MODE_ON
1924	bool "on"
1925	help
1926	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1927	  line parameter.
1928
1929config X86_INTEL_TSX_MODE_AUTO
1930	bool "auto"
1931	help
1932	  TSX is enabled on TSX capable HW that is believed to be safe against
1933	  side channel attacks- equals the tsx=auto command line parameter.
1934endchoice
1935
1936config X86_SGX
1937	bool "Software Guard eXtensions (SGX)"
1938	depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
1939	depends on CRYPTO=y
1940	depends on CRYPTO_SHA256=y
1941	select MMU_NOTIFIER
1942	select NUMA_KEEP_MEMINFO if NUMA
1943	select XARRAY_MULTI
1944	help
1945	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1946	  that can be used by applications to set aside private regions of code
1947	  and data, referred to as enclaves. An enclave's private memory can
1948	  only be accessed by code running within the enclave. Accesses from
1949	  outside the enclave, including other enclaves, are disallowed by
1950	  hardware.
1951
1952	  If unsure, say N.
1953
1954config X86_USER_SHADOW_STACK
1955	bool "X86 userspace shadow stack"
1956	depends on AS_WRUSS
1957	depends on X86_64
1958	select ARCH_USES_HIGH_VMA_FLAGS
1959	select X86_CET
1960	help
1961	  Shadow stack protection is a hardware feature that detects function
1962	  return address corruption.  This helps mitigate ROP attacks.
1963	  Applications must be enabled to use it, and old userspace does not
1964	  get protection "for free".
1965
1966	  CPUs supporting shadow stacks were first released in 2020.
1967
1968	  See Documentation/arch/x86/shstk.rst for more information.
1969
1970	  If unsure, say N.
1971
1972config INTEL_TDX_HOST
1973	bool "Intel Trust Domain Extensions (TDX) host support"
1974	depends on CPU_SUP_INTEL
1975	depends on X86_64
1976	depends on KVM_INTEL
1977	depends on X86_X2APIC
1978	select ARCH_KEEP_MEMBLOCK
1979	depends on CONTIG_ALLOC
1980	depends on !KEXEC_CORE
1981	depends on X86_MCE
1982	help
1983	  Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
1984	  host and certain physical attacks.  This option enables necessary TDX
1985	  support in the host kernel to run confidential VMs.
1986
1987	  If unsure, say N.
1988
1989config EFI
1990	bool "EFI runtime service support"
1991	depends on ACPI
1992	select UCS2_STRING
1993	select EFI_RUNTIME_WRAPPERS
1994	select ARCH_USE_MEMREMAP_PROT
1995	select EFI_RUNTIME_MAP if KEXEC_CORE
1996	help
1997	  This enables the kernel to use EFI runtime services that are
1998	  available (such as the EFI variable services).
1999
2000	  This option is only useful on systems that have EFI firmware.
2001	  In addition, you should use the latest ELILO loader available
2002	  at <http://elilo.sourceforge.net> in order to take advantage
2003	  of EFI runtime services. However, even with this option, the
2004	  resultant kernel should continue to boot on existing non-EFI
2005	  platforms.
2006
2007config EFI_STUB
2008	bool "EFI stub support"
2009	depends on EFI
2010	select RELOCATABLE
2011	help
2012	  This kernel feature allows a bzImage to be loaded directly
2013	  by EFI firmware without the use of a bootloader.
2014
2015	  See Documentation/admin-guide/efi-stub.rst for more information.
2016
2017config EFI_HANDOVER_PROTOCOL
2018	bool "EFI handover protocol (DEPRECATED)"
2019	depends on EFI_STUB
2020	default y
2021	help
2022	  Select this in order to include support for the deprecated EFI
2023	  handover protocol, which defines alternative entry points into the
2024	  EFI stub.  This is a practice that has no basis in the UEFI
2025	  specification, and requires a priori knowledge on the part of the
2026	  bootloader about Linux/x86 specific ways of passing the command line
2027	  and initrd, and where in memory those assets may be loaded.
2028
2029	  If in doubt, say Y. Even though the corresponding support is not
2030	  present in upstream GRUB or other bootloaders, most distros build
2031	  GRUB with numerous downstream patches applied, and may rely on the
2032	  handover protocol as as result.
2033
2034config EFI_MIXED
2035	bool "EFI mixed-mode support"
2036	depends on EFI_STUB && X86_64
2037	help
2038	  Enabling this feature allows a 64-bit kernel to be booted
2039	  on a 32-bit firmware, provided that your CPU supports 64-bit
2040	  mode.
2041
2042	  Note that it is not possible to boot a mixed-mode enabled
2043	  kernel via the EFI boot stub - a bootloader that supports
2044	  the EFI handover protocol must be used.
2045
2046	  If unsure, say N.
2047
2048config EFI_RUNTIME_MAP
2049	bool "Export EFI runtime maps to sysfs" if EXPERT
2050	depends on EFI
2051	help
2052	  Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
2053	  That memory map is required by the 2nd kernel to set up EFI virtual
2054	  mappings after kexec, but can also be used for debugging purposes.
2055
2056	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
2057
2058source "kernel/Kconfig.hz"
2059
2060config ARCH_SUPPORTS_KEXEC
2061	def_bool y
2062
2063config ARCH_SUPPORTS_KEXEC_FILE
2064	def_bool X86_64
2065
2066config ARCH_SELECTS_KEXEC_FILE
2067	def_bool y
2068	depends on KEXEC_FILE
2069	select HAVE_IMA_KEXEC if IMA
2070
2071config ARCH_SUPPORTS_KEXEC_PURGATORY
2072	def_bool y
2073
2074config ARCH_SUPPORTS_KEXEC_SIG
2075	def_bool y
2076
2077config ARCH_SUPPORTS_KEXEC_SIG_FORCE
2078	def_bool y
2079
2080config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
2081	def_bool y
2082
2083config ARCH_SUPPORTS_KEXEC_JUMP
2084	def_bool y
2085
2086config ARCH_SUPPORTS_CRASH_DUMP
2087	def_bool X86_64 || (X86_32 && HIGHMEM)
2088
2089config ARCH_DEFAULT_CRASH_DUMP
2090	def_bool y
2091
2092config ARCH_SUPPORTS_CRASH_HOTPLUG
2093	def_bool y
2094
2095config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
2096	def_bool CRASH_RESERVE
2097
2098config PHYSICAL_START
2099	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2100	default "0x1000000"
2101	help
2102	  This gives the physical address where the kernel is loaded.
2103
2104	  If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
2105	  will decompress itself to above physical address and run from there.
2106	  Otherwise, bzImage will run from the address where it has been loaded
2107	  by the boot loader. The only exception is if it is loaded below the
2108	  above physical address, in which case it will relocate itself there.
2109
2110	  In normal kdump cases one does not have to set/change this option
2111	  as now bzImage can be compiled as a completely relocatable image
2112	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2113	  address. This option is mainly useful for the folks who don't want
2114	  to use a bzImage for capturing the crash dump and want to use a
2115	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2116	  to be specifically compiled to run from a specific memory area
2117	  (normally a reserved region) and this option comes handy.
2118
2119	  So if you are using bzImage for capturing the crash dump,
2120	  leave the value here unchanged to 0x1000000 and set
2121	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2122	  for capturing the crash dump change this value to start of
2123	  the reserved region.  In other words, it can be set based on
2124	  the "X" value as specified in the "crashkernel=YM@XM"
2125	  command line boot parameter passed to the panic-ed
2126	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2127	  for more details about crash dumps.
2128
2129	  Usage of bzImage for capturing the crash dump is recommended as
2130	  one does not have to build two kernels. Same kernel can be used
2131	  as production kernel and capture kernel. Above option should have
2132	  gone away after relocatable bzImage support is introduced. But it
2133	  is present because there are users out there who continue to use
2134	  vmlinux for dump capture. This option should go away down the
2135	  line.
2136
2137	  Don't change this unless you know what you are doing.
2138
2139config RELOCATABLE
2140	bool "Build a relocatable kernel"
2141	default y
2142	help
2143	  This builds a kernel image that retains relocation information
2144	  so it can be loaded someplace besides the default 1MB.
2145	  The relocations tend to make the kernel binary about 10% larger,
2146	  but are discarded at runtime.
2147
2148	  One use is for the kexec on panic case where the recovery kernel
2149	  must live at a different physical address than the primary
2150	  kernel.
2151
2152	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2153	  it has been loaded at and the compile time physical address
2154	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2155
2156config RANDOMIZE_BASE
2157	bool "Randomize the address of the kernel image (KASLR)"
2158	depends on RELOCATABLE
2159	default y
2160	help
2161	  In support of Kernel Address Space Layout Randomization (KASLR),
2162	  this randomizes the physical address at which the kernel image
2163	  is decompressed and the virtual address where the kernel
2164	  image is mapped, as a security feature that deters exploit
2165	  attempts relying on knowledge of the location of kernel
2166	  code internals.
2167
2168	  On 64-bit, the kernel physical and virtual addresses are
2169	  randomized separately. The physical address will be anywhere
2170	  between 16MB and the top of physical memory (up to 64TB). The
2171	  virtual address will be randomized from 16MB up to 1GB (9 bits
2172	  of entropy). Note that this also reduces the memory space
2173	  available to kernel modules from 1.5GB to 1GB.
2174
2175	  On 32-bit, the kernel physical and virtual addresses are
2176	  randomized together. They will be randomized from 16MB up to
2177	  512MB (8 bits of entropy).
2178
2179	  Entropy is generated using the RDRAND instruction if it is
2180	  supported. If RDTSC is supported, its value is mixed into
2181	  the entropy pool as well. If neither RDRAND nor RDTSC are
2182	  supported, then entropy is read from the i8254 timer. The
2183	  usable entropy is limited by the kernel being built using
2184	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2185	  minimum of 2MB. As a result, only 10 bits of entropy are
2186	  theoretically possible, but the implementations are further
2187	  limited due to memory layouts.
2188
2189	  If unsure, say Y.
2190
2191# Relocation on x86 needs some additional build support
2192config X86_NEED_RELOCS
2193	def_bool y
2194	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2195
2196config PHYSICAL_ALIGN
2197	hex "Alignment value to which kernel should be aligned"
2198	default "0x200000"
2199	range 0x2000 0x1000000 if X86_32
2200	range 0x200000 0x1000000 if X86_64
2201	help
2202	  This value puts the alignment restrictions on physical address
2203	  where kernel is loaded and run from. Kernel is compiled for an
2204	  address which meets above alignment restriction.
2205
2206	  If bootloader loads the kernel at a non-aligned address and
2207	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2208	  address aligned to above value and run from there.
2209
2210	  If bootloader loads the kernel at a non-aligned address and
2211	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2212	  load address and decompress itself to the address it has been
2213	  compiled for and run from there. The address for which kernel is
2214	  compiled already meets above alignment restrictions. Hence the
2215	  end result is that kernel runs from a physical address meeting
2216	  above alignment restrictions.
2217
2218	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2219	  this value must be a multiple of 0x200000.
2220
2221	  Don't change this unless you know what you are doing.
2222
2223config DYNAMIC_MEMORY_LAYOUT
2224	bool
2225	help
2226	  This option makes base addresses of vmalloc and vmemmap as well as
2227	  __PAGE_OFFSET movable during boot.
2228
2229config RANDOMIZE_MEMORY
2230	bool "Randomize the kernel memory sections"
2231	depends on X86_64
2232	depends on RANDOMIZE_BASE
2233	select DYNAMIC_MEMORY_LAYOUT
2234	default RANDOMIZE_BASE
2235	help
2236	  Randomizes the base virtual address of kernel memory sections
2237	  (physical memory mapping, vmalloc & vmemmap). This security feature
2238	  makes exploits relying on predictable memory locations less reliable.
2239
2240	  The order of allocations remains unchanged. Entropy is generated in
2241	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2242	  configuration have in average 30,000 different possible virtual
2243	  addresses for each memory section.
2244
2245	  If unsure, say Y.
2246
2247config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2248	hex "Physical memory mapping padding" if EXPERT
2249	depends on RANDOMIZE_MEMORY
2250	default "0xa" if MEMORY_HOTPLUG
2251	default "0x0"
2252	range 0x1 0x40 if MEMORY_HOTPLUG
2253	range 0x0 0x40
2254	help
2255	  Define the padding in terabytes added to the existing physical
2256	  memory size during kernel memory randomization. It is useful
2257	  for memory hotplug support but reduces the entropy available for
2258	  address randomization.
2259
2260	  If unsure, leave at the default value.
2261
2262config ADDRESS_MASKING
2263	bool "Linear Address Masking support"
2264	depends on X86_64
2265	depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
2266	help
2267	  Linear Address Masking (LAM) modifies the checking that is applied
2268	  to 64-bit linear addresses, allowing software to use of the
2269	  untranslated address bits for metadata.
2270
2271	  The capability can be used for efficient address sanitizers (ASAN)
2272	  implementation and for optimizations in JITs.
2273
2274config HOTPLUG_CPU
2275	def_bool y
2276	depends on SMP
2277
2278config COMPAT_VDSO
2279	def_bool n
2280	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2281	depends on COMPAT_32
2282	help
2283	  Certain buggy versions of glibc will crash if they are
2284	  presented with a 32-bit vDSO that is not mapped at the address
2285	  indicated in its segment table.
2286
2287	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2288	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2289	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2290	  the only released version with the bug, but OpenSUSE 9
2291	  contains a buggy "glibc 2.3.2".
2292
2293	  The symptom of the bug is that everything crashes on startup, saying:
2294	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2295
2296	  Saying Y here changes the default value of the vdso32 boot
2297	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2298	  This works around the glibc bug but hurts performance.
2299
2300	  If unsure, say N: if you are compiling your own kernel, you
2301	  are unlikely to be using a buggy version of glibc.
2302
2303choice
2304	prompt "vsyscall table for legacy applications"
2305	depends on X86_64
2306	default LEGACY_VSYSCALL_XONLY
2307	help
2308	  Legacy user code that does not know how to find the vDSO expects
2309	  to be able to issue three syscalls by calling fixed addresses in
2310	  kernel space. Since this location is not randomized with ASLR,
2311	  it can be used to assist security vulnerability exploitation.
2312
2313	  This setting can be changed at boot time via the kernel command
2314	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2315	  is deprecated and can only be enabled using the kernel command
2316	  line.
2317
2318	  On a system with recent enough glibc (2.14 or newer) and no
2319	  static binaries, you can say None without a performance penalty
2320	  to improve security.
2321
2322	  If unsure, select "Emulate execution only".
2323
2324	config LEGACY_VSYSCALL_XONLY
2325		bool "Emulate execution only"
2326		help
2327		  The kernel traps and emulates calls into the fixed vsyscall
2328		  address mapping and does not allow reads.  This
2329		  configuration is recommended when userspace might use the
2330		  legacy vsyscall area but support for legacy binary
2331		  instrumentation of legacy code is not needed.  It mitigates
2332		  certain uses of the vsyscall area as an ASLR-bypassing
2333		  buffer.
2334
2335	config LEGACY_VSYSCALL_NONE
2336		bool "None"
2337		help
2338		  There will be no vsyscall mapping at all. This will
2339		  eliminate any risk of ASLR bypass due to the vsyscall
2340		  fixed address mapping. Attempts to use the vsyscalls
2341		  will be reported to dmesg, so that either old or
2342		  malicious userspace programs can be identified.
2343
2344endchoice
2345
2346config CMDLINE_BOOL
2347	bool "Built-in kernel command line"
2348	help
2349	  Allow for specifying boot arguments to the kernel at
2350	  build time.  On some systems (e.g. embedded ones), it is
2351	  necessary or convenient to provide some or all of the
2352	  kernel boot arguments with the kernel itself (that is,
2353	  to not rely on the boot loader to provide them.)
2354
2355	  To compile command line arguments into the kernel,
2356	  set this option to 'Y', then fill in the
2357	  boot arguments in CONFIG_CMDLINE.
2358
2359	  Systems with fully functional boot loaders (i.e. non-embedded)
2360	  should leave this option set to 'N'.
2361
2362config CMDLINE
2363	string "Built-in kernel command string"
2364	depends on CMDLINE_BOOL
2365	default ""
2366	help
2367	  Enter arguments here that should be compiled into the kernel
2368	  image and used at boot time.  If the boot loader provides a
2369	  command line at boot time, it is appended to this string to
2370	  form the full kernel command line, when the system boots.
2371
2372	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2373	  change this behavior.
2374
2375	  In most cases, the command line (whether built-in or provided
2376	  by the boot loader) should specify the device for the root
2377	  file system.
2378
2379config CMDLINE_OVERRIDE
2380	bool "Built-in command line overrides boot loader arguments"
2381	depends on CMDLINE_BOOL && CMDLINE != ""
2382	help
2383	  Set this option to 'Y' to have the kernel ignore the boot loader
2384	  command line, and use ONLY the built-in command line.
2385
2386	  This is used to work around broken boot loaders.  This should
2387	  be set to 'N' under normal conditions.
2388
2389config MODIFY_LDT_SYSCALL
2390	bool "Enable the LDT (local descriptor table)" if EXPERT
2391	default y
2392	help
2393	  Linux can allow user programs to install a per-process x86
2394	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2395	  call.  This is required to run 16-bit or segmented code such as
2396	  DOSEMU or some Wine programs.  It is also used by some very old
2397	  threading libraries.
2398
2399	  Enabling this feature adds a small amount of overhead to
2400	  context switches and increases the low-level kernel attack
2401	  surface.  Disabling it removes the modify_ldt(2) system call.
2402
2403	  Saying 'N' here may make sense for embedded or server kernels.
2404
2405config STRICT_SIGALTSTACK_SIZE
2406	bool "Enforce strict size checking for sigaltstack"
2407	depends on DYNAMIC_SIGFRAME
2408	help
2409	  For historical reasons MINSIGSTKSZ is a constant which became
2410	  already too small with AVX512 support. Add a mechanism to
2411	  enforce strict checking of the sigaltstack size against the
2412	  real size of the FPU frame. This option enables the check
2413	  by default. It can also be controlled via the kernel command
2414	  line option 'strict_sas_size' independent of this config
2415	  switch. Enabling it might break existing applications which
2416	  allocate a too small sigaltstack but 'work' because they
2417	  never get a signal delivered.
2418
2419	  Say 'N' unless you want to really enforce this check.
2420
2421config CFI_AUTO_DEFAULT
2422	bool "Attempt to use FineIBT by default at boot time"
2423	depends on FINEIBT
2424	depends on !RUST || RUSTC_VERSION >= 108800
2425	default y
2426	help
2427	  Attempt to use FineIBT by default at boot time. If enabled,
2428	  this is the same as booting with "cfi=auto". If disabled,
2429	  this is the same as booting with "cfi=kcfi".
2430
2431source "kernel/livepatch/Kconfig"
2432
2433endmenu
2434
2435config CC_HAS_NAMED_AS
2436	def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
2437	depends on CC_IS_GCC
2438
2439#
2440# -fsanitize=kernel-address (KASAN) and -fsanitize=thread (KCSAN)
2441# are incompatible with named address spaces with GCC < 13.3
2442# (see GCC PR sanitizer/111736 and also PR sanitizer/115172).
2443#
2444
2445config CC_HAS_NAMED_AS_FIXED_SANITIZERS
2446	def_bool y
2447	depends on !(KASAN || KCSAN) || GCC_VERSION >= 130300
2448	depends on !(UBSAN_BOOL && KASAN) || GCC_VERSION >= 140200
2449
2450config USE_X86_SEG_SUPPORT
2451	def_bool CC_HAS_NAMED_AS
2452	depends on CC_HAS_NAMED_AS_FIXED_SANITIZERS
2453
2454config CC_HAS_SLS
2455	def_bool $(cc-option,-mharden-sls=all)
2456
2457config CC_HAS_RETURN_THUNK
2458	def_bool $(cc-option,-mfunction-return=thunk-extern)
2459
2460config CC_HAS_ENTRY_PADDING
2461	def_bool $(cc-option,-fpatchable-function-entry=16,16)
2462
2463config FUNCTION_PADDING_CFI
2464	int
2465	default 59 if FUNCTION_ALIGNMENT_64B
2466	default 27 if FUNCTION_ALIGNMENT_32B
2467	default 11 if FUNCTION_ALIGNMENT_16B
2468	default  3 if FUNCTION_ALIGNMENT_8B
2469	default  0
2470
2471# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
2472# except Kconfig can't do arithmetic :/
2473config FUNCTION_PADDING_BYTES
2474	int
2475	default FUNCTION_PADDING_CFI if CFI_CLANG
2476	default FUNCTION_ALIGNMENT
2477
2478config CALL_PADDING
2479	def_bool n
2480	depends on CC_HAS_ENTRY_PADDING && OBJTOOL
2481	select FUNCTION_ALIGNMENT_16B
2482
2483config FINEIBT
2484	def_bool y
2485	depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
2486	select CALL_PADDING
2487
2488config HAVE_CALL_THUNKS
2489	def_bool y
2490	depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
2491
2492config CALL_THUNKS
2493	def_bool n
2494	select CALL_PADDING
2495
2496config PREFIX_SYMBOLS
2497	def_bool y
2498	depends on CALL_PADDING && !CFI_CLANG
2499
2500menuconfig CPU_MITIGATIONS
2501	bool "Mitigations for CPU vulnerabilities"
2502	default y
2503	help
2504	  Say Y here to enable options which enable mitigations for hardware
2505	  vulnerabilities (usually related to speculative execution).
2506	  Mitigations can be disabled or restricted to SMT systems at runtime
2507	  via the "mitigations" kernel parameter.
2508
2509	  If you say N, all mitigations will be disabled.  This CANNOT be
2510	  overridden at runtime.
2511
2512	  Say 'Y', unless you really know what you are doing.
2513
2514if CPU_MITIGATIONS
2515
2516config MITIGATION_PAGE_TABLE_ISOLATION
2517	bool "Remove the kernel mapping in user mode"
2518	default y
2519	depends on (X86_64 || X86_PAE)
2520	help
2521	  This feature reduces the number of hardware side channels by
2522	  ensuring that the majority of kernel addresses are not mapped
2523	  into userspace.
2524
2525	  See Documentation/arch/x86/pti.rst for more details.
2526
2527config MITIGATION_RETPOLINE
2528	bool "Avoid speculative indirect branches in kernel"
2529	select OBJTOOL if HAVE_OBJTOOL
2530	default y
2531	help
2532	  Compile kernel with the retpoline compiler options to guard against
2533	  kernel-to-user data leaks by avoiding speculative indirect
2534	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2535	  support for full protection. The kernel may run slower.
2536
2537config MITIGATION_RETHUNK
2538	bool "Enable return-thunks"
2539	depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
2540	select OBJTOOL if HAVE_OBJTOOL
2541	default y if X86_64
2542	help
2543	  Compile the kernel with the return-thunks compiler option to guard
2544	  against kernel-to-user data leaks by avoiding return speculation.
2545	  Requires a compiler with -mfunction-return=thunk-extern
2546	  support for full protection. The kernel may run slower.
2547
2548config MITIGATION_UNRET_ENTRY
2549	bool "Enable UNRET on kernel entry"
2550	depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
2551	default y
2552	help
2553	  Compile the kernel with support for the retbleed=unret mitigation.
2554
2555config MITIGATION_CALL_DEPTH_TRACKING
2556	bool "Mitigate RSB underflow with call depth tracking"
2557	depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
2558	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
2559	select CALL_THUNKS
2560	default y
2561	help
2562	  Compile the kernel with call depth tracking to mitigate the Intel
2563	  SKL Return-Speculation-Buffer (RSB) underflow issue. The
2564	  mitigation is off by default and needs to be enabled on the
2565	  kernel command line via the retbleed=stuff option. For
2566	  non-affected systems the overhead of this option is marginal as
2567	  the call depth tracking is using run-time generated call thunks
2568	  in a compiler generated padding area and call patching. This
2569	  increases text size by ~5%. For non affected systems this space
2570	  is unused. On affected SKL systems this results in a significant
2571	  performance gain over the IBRS mitigation.
2572
2573config CALL_THUNKS_DEBUG
2574	bool "Enable call thunks and call depth tracking debugging"
2575	depends on MITIGATION_CALL_DEPTH_TRACKING
2576	select FUNCTION_ALIGNMENT_32B
2577	default n
2578	help
2579	  Enable call/ret counters for imbalance detection and build in
2580	  a noisy dmesg about callthunks generation and call patching for
2581	  trouble shooting. The debug prints need to be enabled on the
2582	  kernel command line with 'debug-callthunks'.
2583	  Only enable this when you are debugging call thunks as this
2584	  creates a noticeable runtime overhead. If unsure say N.
2585
2586config MITIGATION_IBPB_ENTRY
2587	bool "Enable IBPB on kernel entry"
2588	depends on CPU_SUP_AMD && X86_64
2589	default y
2590	help
2591	  Compile the kernel with support for the retbleed=ibpb and
2592	  spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations.
2593
2594config MITIGATION_IBRS_ENTRY
2595	bool "Enable IBRS on kernel entry"
2596	depends on CPU_SUP_INTEL && X86_64
2597	default y
2598	help
2599	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2600	  This mitigates both spectre_v2 and retbleed at great cost to
2601	  performance.
2602
2603config MITIGATION_SRSO
2604	bool "Mitigate speculative RAS overflow on AMD"
2605	depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
2606	default y
2607	help
2608	  Enable the SRSO mitigation needed on AMD Zen1-4 machines.
2609
2610config MITIGATION_SLS
2611	bool "Mitigate Straight-Line-Speculation"
2612	depends on CC_HAS_SLS && X86_64
2613	select OBJTOOL if HAVE_OBJTOOL
2614	default n
2615	help
2616	  Compile the kernel with straight-line-speculation options to guard
2617	  against straight line speculation. The kernel image might be slightly
2618	  larger.
2619
2620config MITIGATION_GDS
2621	bool "Mitigate Gather Data Sampling"
2622	depends on CPU_SUP_INTEL
2623	default y
2624	help
2625	  Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
2626	  vulnerability which allows unprivileged speculative access to data
2627	  which was previously stored in vector registers. The attacker uses gather
2628	  instructions to infer the stale vector register data.
2629
2630config MITIGATION_RFDS
2631	bool "RFDS Mitigation"
2632	depends on CPU_SUP_INTEL
2633	default y
2634	help
2635	  Enable mitigation for Register File Data Sampling (RFDS) by default.
2636	  RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
2637	  allows unprivileged speculative access to stale data previously
2638	  stored in floating point, vector and integer registers.
2639	  See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
2640
2641config MITIGATION_SPECTRE_BHI
2642	bool "Mitigate Spectre-BHB (Branch History Injection)"
2643	depends on CPU_SUP_INTEL
2644	default y
2645	help
2646	  Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
2647	  where the branch history buffer is poisoned to speculatively steer
2648	  indirect branches.
2649	  See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2650
2651config MITIGATION_MDS
2652	bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
2653	depends on CPU_SUP_INTEL
2654	default y
2655	help
2656	  Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
2657	  a hardware vulnerability which allows unprivileged speculative access
2658	  to data which is available in various CPU internal buffers.
2659	  See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
2660
2661config MITIGATION_TAA
2662	bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
2663	depends on CPU_SUP_INTEL
2664	default y
2665	help
2666	  Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
2667	  vulnerability that allows unprivileged speculative access to data
2668	  which is available in various CPU internal buffers by using
2669	  asynchronous aborts within an Intel TSX transactional region.
2670	  See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
2671
2672config MITIGATION_MMIO_STALE_DATA
2673	bool "Mitigate MMIO Stale Data hardware bug"
2674	depends on CPU_SUP_INTEL
2675	default y
2676	help
2677	  Enable mitigation for MMIO Stale Data hardware bugs.  Processor MMIO
2678	  Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
2679	  vulnerabilities that can expose data. The vulnerabilities require the
2680	  attacker to have access to MMIO.
2681	  See also
2682	  <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
2683
2684config MITIGATION_L1TF
2685	bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
2686	depends on CPU_SUP_INTEL
2687	default y
2688	help
2689	  Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
2690	  hardware vulnerability which allows unprivileged speculative access to data
2691	  available in the Level 1 Data Cache.
2692	  See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
2693
2694config MITIGATION_RETBLEED
2695	bool "Mitigate RETBleed hardware bug"
2696	depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
2697	default y
2698	help
2699	  Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
2700	  with Return Instructions) vulnerability.  RETBleed is a speculative
2701	  execution attack which takes advantage of microarchitectural behavior
2702	  in many modern microprocessors, similar to Spectre v2. An
2703	  unprivileged attacker can use these flaws to bypass conventional
2704	  memory security restrictions to gain read access to privileged memory
2705	  that would otherwise be inaccessible.
2706
2707config MITIGATION_SPECTRE_V1
2708	bool "Mitigate SPECTRE V1 hardware bug"
2709	default y
2710	help
2711	  Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
2712	  class of side channel attacks that takes advantage of speculative
2713	  execution that bypasses conditional branch instructions used for
2714	  memory access bounds check.
2715	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2716
2717config MITIGATION_SPECTRE_V2
2718	bool "Mitigate SPECTRE V2 hardware bug"
2719	default y
2720	help
2721	  Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
2722	  V2 is a class of side channel attacks that takes advantage of
2723	  indirect branch predictors inside the processor. In Spectre variant 2
2724	  attacks, the attacker can steer speculative indirect branches in the
2725	  victim to gadget code by poisoning the branch target buffer of a CPU
2726	  used for predicting indirect branch addresses.
2727	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
2728
2729config MITIGATION_SRBDS
2730	bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
2731	depends on CPU_SUP_INTEL
2732	default y
2733	help
2734	  Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
2735	  SRBDS is a hardware vulnerability that allows Microarchitectural Data
2736	  Sampling (MDS) techniques to infer values returned from special
2737	  register accesses. An unprivileged user can extract values returned
2738	  from RDRAND and RDSEED executed on another core or sibling thread
2739	  using MDS techniques.
2740	  See also
2741	  <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
2742
2743config MITIGATION_SSB
2744	bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
2745	default y
2746	help
2747	  Enable mitigation for Speculative Store Bypass (SSB). SSB is a
2748	  hardware security vulnerability and its exploitation takes advantage
2749	  of speculative execution in a similar way to the Meltdown and Spectre
2750	  security vulnerabilities.
2751
2752config MITIGATION_ITS
2753	bool "Enable Indirect Target Selection mitigation"
2754	depends on CPU_SUP_INTEL && X86_64
2755	depends on MITIGATION_RETPOLINE && MITIGATION_RETHUNK
2756	select EXECMEM
2757	default y
2758	help
2759	  Enable Indirect Target Selection (ITS) mitigation. ITS is a bug in
2760	  BPU on some Intel CPUs that may allow Spectre V2 style attacks. If
2761	  disabled, mitigation cannot be enabled via cmdline.
2762	  See <file:Documentation/admin-guide/hw-vuln/indirect-target-selection.rst>
2763
2764config MITIGATION_TSA
2765	bool "Mitigate Transient Scheduler Attacks"
2766	depends on CPU_SUP_AMD
2767	default y
2768	help
2769	  Enable mitigation for Transient Scheduler Attacks. TSA is a hardware
2770	  security vulnerability on AMD CPUs which can lead to forwarding of
2771	  invalid info to subsequent instructions and thus can affect their
2772	  timing and thereby cause a leakage.
2773
2774config MITIGATION_VMSCAPE
2775	bool "Mitigate VMSCAPE"
2776	depends on KVM
2777	default y
2778	help
2779	  Enable mitigation for VMSCAPE attacks. VMSCAPE is a hardware security
2780	  vulnerability on Intel and AMD CPUs that may allow a guest to do
2781	  Spectre v2 style attacks on userspace hypervisor.
2782endif
2783
2784config ARCH_HAS_ADD_PAGES
2785	def_bool y
2786	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2787
2788menu "Power management and ACPI options"
2789
2790config ARCH_HIBERNATION_HEADER
2791	def_bool y
2792	depends on HIBERNATION
2793
2794source "kernel/power/Kconfig"
2795
2796source "drivers/acpi/Kconfig"
2797
2798config X86_APM_BOOT
2799	def_bool y
2800	depends on APM
2801
2802menuconfig APM
2803	tristate "APM (Advanced Power Management) BIOS support"
2804	depends on X86_32 && PM_SLEEP
2805	help
2806	  APM is a BIOS specification for saving power using several different
2807	  techniques. This is mostly useful for battery powered laptops with
2808	  APM compliant BIOSes. If you say Y here, the system time will be
2809	  reset after a RESUME operation, the /proc/apm device will provide
2810	  battery status information, and user-space programs will receive
2811	  notification of APM "events" (e.g. battery status change).
2812
2813	  If you select "Y" here, you can disable actual use of the APM
2814	  BIOS by passing the "apm=off" option to the kernel at boot time.
2815
2816	  Note that the APM support is almost completely disabled for
2817	  machines with more than one CPU.
2818
2819	  In order to use APM, you will need supporting software. For location
2820	  and more information, read <file:Documentation/power/apm-acpi.rst>
2821	  and the Battery Powered Linux mini-HOWTO, available from
2822	  <http://www.tldp.org/docs.html#howto>.
2823
2824	  This driver does not spin down disk drives (see the hdparm(8)
2825	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2826	  VESA-compliant "green" monitors.
2827
2828	  This driver does not support the TI 4000M TravelMate and the ACER
2829	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2830	  desktop machines also don't have compliant BIOSes, and this driver
2831	  may cause those machines to panic during the boot phase.
2832
2833	  Generally, if you don't have a battery in your machine, there isn't
2834	  much point in using this driver and you should say N. If you get
2835	  random kernel OOPSes or reboots that don't seem to be related to
2836	  anything, try disabling/enabling this option (or disabling/enabling
2837	  APM in your BIOS).
2838
2839	  Some other things you should try when experiencing seemingly random,
2840	  "weird" problems:
2841
2842	  1) make sure that you have enough swap space and that it is
2843	  enabled.
2844	  2) pass the "idle=poll" option to the kernel
2845	  3) switch on floating point emulation in the kernel and pass
2846	  the "no387" option to the kernel
2847	  4) pass the "floppy=nodma" option to the kernel
2848	  5) pass the "mem=4M" option to the kernel (thereby disabling
2849	  all but the first 4 MB of RAM)
2850	  6) make sure that the CPU is not over clocked.
2851	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2852	  8) disable the cache from your BIOS settings
2853	  9) install a fan for the video card or exchange video RAM
2854	  10) install a better fan for the CPU
2855	  11) exchange RAM chips
2856	  12) exchange the motherboard.
2857
2858	  To compile this driver as a module, choose M here: the
2859	  module will be called apm.
2860
2861if APM
2862
2863config APM_IGNORE_USER_SUSPEND
2864	bool "Ignore USER SUSPEND"
2865	help
2866	  This option will ignore USER SUSPEND requests. On machines with a
2867	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2868	  series notebooks, it is necessary to say Y because of a BIOS bug.
2869
2870config APM_DO_ENABLE
2871	bool "Enable PM at boot time"
2872	help
2873	  Enable APM features at boot time. From page 36 of the APM BIOS
2874	  specification: "When disabled, the APM BIOS does not automatically
2875	  power manage devices, enter the Standby State, enter the Suspend
2876	  State, or take power saving steps in response to CPU Idle calls."
2877	  This driver will make CPU Idle calls when Linux is idle (unless this
2878	  feature is turned off -- see "Do CPU IDLE calls", below). This
2879	  should always save battery power, but more complicated APM features
2880	  will be dependent on your BIOS implementation. You may need to turn
2881	  this option off if your computer hangs at boot time when using APM
2882	  support, or if it beeps continuously instead of suspending. Turn
2883	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2884	  T400CDT. This is off by default since most machines do fine without
2885	  this feature.
2886
2887config APM_CPU_IDLE
2888	depends on CPU_IDLE
2889	bool "Make CPU Idle calls when idle"
2890	help
2891	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2892	  On some machines, this can activate improved power savings, such as
2893	  a slowed CPU clock rate, when the machine is idle. These idle calls
2894	  are made after the idle loop has run for some length of time (e.g.,
2895	  333 mS). On some machines, this will cause a hang at boot time or
2896	  whenever the CPU becomes idle. (On machines with more than one CPU,
2897	  this option does nothing.)
2898
2899config APM_DISPLAY_BLANK
2900	bool "Enable console blanking using APM"
2901	help
2902	  Enable console blanking using the APM. Some laptops can use this to
2903	  turn off the LCD backlight when the screen blanker of the Linux
2904	  virtual console blanks the screen. Note that this is only used by
2905	  the virtual console screen blanker, and won't turn off the backlight
2906	  when using the X Window system. This also doesn't have anything to
2907	  do with your VESA-compliant power-saving monitor. Further, this
2908	  option doesn't work for all laptops -- it might not turn off your
2909	  backlight at all, or it might print a lot of errors to the console,
2910	  especially if you are using gpm.
2911
2912config APM_ALLOW_INTS
2913	bool "Allow interrupts during APM BIOS calls"
2914	help
2915	  Normally we disable external interrupts while we are making calls to
2916	  the APM BIOS as a measure to lessen the effects of a badly behaving
2917	  BIOS implementation.  The BIOS should reenable interrupts if it
2918	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2919	  many of the newer IBM Thinkpads.  If you experience hangs when you
2920	  suspend, try setting this to Y.  Otherwise, say N.
2921
2922endif # APM
2923
2924source "drivers/cpufreq/Kconfig"
2925
2926source "drivers/cpuidle/Kconfig"
2927
2928source "drivers/idle/Kconfig"
2929
2930endmenu
2931
2932menu "Bus options (PCI etc.)"
2933
2934choice
2935	prompt "PCI access mode"
2936	depends on X86_32 && PCI
2937	default PCI_GOANY
2938	help
2939	  On PCI systems, the BIOS can be used to detect the PCI devices and
2940	  determine their configuration. However, some old PCI motherboards
2941	  have BIOS bugs and may crash if this is done. Also, some embedded
2942	  PCI-based systems don't have any BIOS at all. Linux can also try to
2943	  detect the PCI hardware directly without using the BIOS.
2944
2945	  With this option, you can specify how Linux should detect the
2946	  PCI devices. If you choose "BIOS", the BIOS will be used,
2947	  if you choose "Direct", the BIOS won't be used, and if you
2948	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2949	  If you choose "Any", the kernel will try MMCONFIG, then the
2950	  direct access method and falls back to the BIOS if that doesn't
2951	  work. If unsure, go with the default, which is "Any".
2952
2953config PCI_GOBIOS
2954	bool "BIOS"
2955
2956config PCI_GOMMCONFIG
2957	bool "MMConfig"
2958
2959config PCI_GODIRECT
2960	bool "Direct"
2961
2962config PCI_GOOLPC
2963	bool "OLPC XO-1"
2964	depends on OLPC
2965
2966config PCI_GOANY
2967	bool "Any"
2968
2969endchoice
2970
2971config PCI_BIOS
2972	def_bool y
2973	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2974
2975# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2976config PCI_DIRECT
2977	def_bool y
2978	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2979
2980config PCI_MMCONFIG
2981	bool "Support mmconfig PCI config space access" if X86_64
2982	default y
2983	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2984	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2985
2986config PCI_OLPC
2987	def_bool y
2988	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2989
2990config PCI_XEN
2991	def_bool y
2992	depends on PCI && XEN
2993
2994config MMCONF_FAM10H
2995	def_bool y
2996	depends on X86_64 && PCI_MMCONFIG && ACPI
2997
2998config PCI_CNB20LE_QUIRK
2999	bool "Read CNB20LE Host Bridge Windows" if EXPERT
3000	depends on PCI
3001	help
3002	  Read the PCI windows out of the CNB20LE host bridge. This allows
3003	  PCI hotplug to work on systems with the CNB20LE chipset which do
3004	  not have ACPI.
3005
3006	  There's no public spec for this chipset, and this functionality
3007	  is known to be incomplete.
3008
3009	  You should say N unless you know you need this.
3010
3011config ISA_BUS
3012	bool "ISA bus support on modern systems" if EXPERT
3013	help
3014	  Expose ISA bus device drivers and options available for selection and
3015	  configuration. Enable this option if your target machine has an ISA
3016	  bus. ISA is an older system, displaced by PCI and newer bus
3017	  architectures -- if your target machine is modern, it probably does
3018	  not have an ISA bus.
3019
3020	  If unsure, say N.
3021
3022# x86_64 have no ISA slots, but can have ISA-style DMA.
3023config ISA_DMA_API
3024	bool "ISA-style DMA support" if (X86_64 && EXPERT)
3025	default y
3026	help
3027	  Enables ISA-style DMA support for devices requiring such controllers.
3028	  If unsure, say Y.
3029
3030if X86_32
3031
3032config ISA
3033	bool "ISA support"
3034	help
3035	  Find out whether you have ISA slots on your motherboard.  ISA is the
3036	  name of a bus system, i.e. the way the CPU talks to the other stuff
3037	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
3038	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
3039	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
3040
3041config SCx200
3042	tristate "NatSemi SCx200 support"
3043	help
3044	  This provides basic support for National Semiconductor's
3045	  (now AMD's) Geode processors.  The driver probes for the
3046	  PCI-IDs of several on-chip devices, so its a good dependency
3047	  for other scx200_* drivers.
3048
3049	  If compiled as a module, the driver is named scx200.
3050
3051config SCx200HR_TIMER
3052	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
3053	depends on SCx200
3054	default y
3055	help
3056	  This driver provides a clocksource built upon the on-chip
3057	  27MHz high-resolution timer.  Its also a workaround for
3058	  NSC Geode SC-1100's buggy TSC, which loses time when the
3059	  processor goes idle (as is done by the scheduler).  The
3060	  other workaround is idle=poll boot option.
3061
3062config OLPC
3063	bool "One Laptop Per Child support"
3064	depends on !X86_PAE
3065	select GPIOLIB
3066	select OF
3067	select OF_PROMTREE
3068	select IRQ_DOMAIN
3069	select OLPC_EC
3070	help
3071	  Add support for detecting the unique features of the OLPC
3072	  XO hardware.
3073
3074config OLPC_XO1_PM
3075	bool "OLPC XO-1 Power Management"
3076	depends on OLPC && MFD_CS5535=y && PM_SLEEP
3077	help
3078	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
3079
3080config OLPC_XO1_RTC
3081	bool "OLPC XO-1 Real Time Clock"
3082	depends on OLPC_XO1_PM && RTC_DRV_CMOS
3083	help
3084	  Add support for the XO-1 real time clock, which can be used as a
3085	  programmable wakeup source.
3086
3087config OLPC_XO1_SCI
3088	bool "OLPC XO-1 SCI extras"
3089	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
3090	depends on INPUT=y
3091	select POWER_SUPPLY
3092	help
3093	  Add support for SCI-based features of the OLPC XO-1 laptop:
3094	   - EC-driven system wakeups
3095	   - Power button
3096	   - Ebook switch
3097	   - Lid switch
3098	   - AC adapter status updates
3099	   - Battery status updates
3100
3101config OLPC_XO15_SCI
3102	bool "OLPC XO-1.5 SCI extras"
3103	depends on OLPC && ACPI
3104	select POWER_SUPPLY
3105	help
3106	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
3107	   - EC-driven system wakeups
3108	   - AC adapter status updates
3109	   - Battery status updates
3110
3111config GEODE_COMMON
3112	bool
3113
3114config ALIX
3115	bool "PCEngines ALIX System Support (LED setup)"
3116	select GPIOLIB
3117	select GEODE_COMMON
3118	help
3119	  This option enables system support for the PCEngines ALIX.
3120	  At present this just sets up LEDs for GPIO control on
3121	  ALIX2/3/6 boards.  However, other system specific setup should
3122	  get added here.
3123
3124	  Note: You must still enable the drivers for GPIO and LED support
3125	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
3126
3127	  Note: You have to set alix.force=1 for boards with Award BIOS.
3128
3129config NET5501
3130	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
3131	select GPIOLIB
3132	select GEODE_COMMON
3133	help
3134	  This option enables system support for the Soekris Engineering net5501.
3135
3136config GEOS
3137	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
3138	select GPIOLIB
3139	select GEODE_COMMON
3140	depends on DMI
3141	help
3142	  This option enables system support for the Traverse Technologies GEOS.
3143
3144config TS5500
3145	bool "Technologic Systems TS-5500 platform support"
3146	depends on MELAN
3147	select CHECK_SIGNATURE
3148	select NEW_LEDS
3149	select LEDS_CLASS
3150	help
3151	  This option enables system support for the Technologic Systems TS-5500.
3152
3153endif # X86_32
3154
3155config AMD_NB
3156	def_bool y
3157	depends on CPU_SUP_AMD && PCI
3158
3159endmenu
3160
3161menu "Binary Emulations"
3162
3163config IA32_EMULATION
3164	bool "IA32 Emulation"
3165	depends on X86_64
3166	select ARCH_WANT_OLD_COMPAT_IPC
3167	select BINFMT_ELF
3168	select COMPAT_OLD_SIGACTION
3169	help
3170	  Include code to run legacy 32-bit programs under a
3171	  64-bit kernel. You should likely turn this on, unless you're
3172	  100% sure that you don't have any 32-bit programs left.
3173
3174config IA32_EMULATION_DEFAULT_DISABLED
3175	bool "IA32 emulation disabled by default"
3176	default n
3177	depends on IA32_EMULATION
3178	help
3179	  Make IA32 emulation disabled by default. This prevents loading 32-bit
3180	  processes and access to 32-bit syscalls. If unsure, leave it to its
3181	  default value.
3182
3183config X86_X32_ABI
3184	bool "x32 ABI for 64-bit mode"
3185	depends on X86_64
3186	# llvm-objcopy does not convert x86_64 .note.gnu.property or
3187	# compressed debug sections to x86_x32 properly:
3188	# https://github.com/ClangBuiltLinux/linux/issues/514
3189	# https://github.com/ClangBuiltLinux/linux/issues/1141
3190	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
3191	help
3192	  Include code to run binaries for the x32 native 32-bit ABI
3193	  for 64-bit processors.  An x32 process gets access to the
3194	  full 64-bit register file and wide data path while leaving
3195	  pointers at 32 bits for smaller memory footprint.
3196
3197config COMPAT_32
3198	def_bool y
3199	depends on IA32_EMULATION || X86_32
3200	select HAVE_UID16
3201	select OLD_SIGSUSPEND3
3202
3203config COMPAT
3204	def_bool y
3205	depends on IA32_EMULATION || X86_X32_ABI
3206
3207config COMPAT_FOR_U64_ALIGNMENT
3208	def_bool y
3209	depends on COMPAT
3210
3211endmenu
3212
3213config HAVE_ATOMIC_IOMAP
3214	def_bool y
3215	depends on X86_32
3216
3217source "arch/x86/kvm/Kconfig"
3218
3219source "arch/x86/Kconfig.assembler"
3220