xref: /openbmc/linux/arch/x86/Kconfig (revision e9088629)
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_USE_CMPXCHG_LOCKREF
31	select HAVE_ARCH_SOFT_DIRTY
32	select MODULES_USE_ELF_RELA
33	select NEED_DMA_MAP_STATE
34	select SWIOTLB
35	select ARCH_HAS_ELFCORE_COMPAT
36	select ZONE_DMA32
37
38config FORCE_DYNAMIC_FTRACE
39	def_bool y
40	depends on X86_32
41	depends on FUNCTION_TRACER
42	select DYNAMIC_FTRACE
43	help
44	  We keep the static function tracing (!DYNAMIC_FTRACE) around
45	  in order to test the non static function tracing in the
46	  generic code, as other architectures still use it. But we
47	  only need to keep it around for x86_64. No need to keep it
48	  for x86_32. For x86_32, force DYNAMIC_FTRACE.
49#
50# Arch settings
51#
52# ( Note that options that are marked 'if X86_64' could in principle be
53#   ported to 32-bit as well. )
54#
55config X86
56	def_bool y
57	#
58	# Note: keep this list sorted alphabetically
59	#
60	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
61	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
62	select ARCH_32BIT_OFF_T			if X86_32
63	select ARCH_CLOCKSOURCE_INIT
64	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
71	select ARCH_HAS_CACHE_LINE_SIZE
72	select ARCH_HAS_CURRENT_STACK_POINTER
73	select ARCH_HAS_DEBUG_VIRTUAL
74	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
75	select ARCH_HAS_DEVMEM_IS_ALLOWED
76	select ARCH_HAS_EARLY_DEBUG		if KGDB
77	select ARCH_HAS_ELF_RANDOMIZE
78	select ARCH_HAS_FAST_MULTIPLIER
79	select ARCH_HAS_FORTIFY_SOURCE
80	select ARCH_HAS_GCOV_PROFILE_ALL
81	select ARCH_HAS_KCOV			if X86_64
82	select ARCH_HAS_MEM_ENCRYPT
83	select ARCH_HAS_MEMBARRIER_SYNC_CORE
84	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85	select ARCH_HAS_PMEM_API		if X86_64
86	select ARCH_HAS_PTE_DEVMAP		if X86_64
87	select ARCH_HAS_PTE_SPECIAL
88	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
89	select ARCH_HAS_COPY_MC			if X86_64
90	select ARCH_HAS_SET_MEMORY
91	select ARCH_HAS_SET_DIRECT_MAP
92	select ARCH_HAS_STRICT_KERNEL_RWX
93	select ARCH_HAS_STRICT_MODULE_RWX
94	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95	select ARCH_HAS_SYSCALL_WRAPPER
96	select ARCH_HAS_UBSAN_SANITIZE_ALL
97	select ARCH_HAS_VM_GET_PAGE_PROT
98	select ARCH_HAS_DEBUG_WX
99	select ARCH_HAS_ZONE_DMA_SET if EXPERT
100	select ARCH_HAVE_NMI_SAFE_CMPXCHG
101	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
102	select ARCH_MIGHT_HAVE_PC_PARPORT
103	select ARCH_MIGHT_HAVE_PC_SERIO
104	select ARCH_STACKWALK
105	select ARCH_SUPPORTS_ACPI
106	select ARCH_SUPPORTS_ATOMIC_RMW
107	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
108	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
109	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
110	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
111	select ARCH_SUPPORTS_LTO_CLANG
112	select ARCH_SUPPORTS_LTO_CLANG_THIN
113	select ARCH_USE_BUILTIN_BSWAP
114	select ARCH_USE_MEMTEST
115	select ARCH_USE_QUEUED_RWLOCKS
116	select ARCH_USE_QUEUED_SPINLOCKS
117	select ARCH_USE_SYM_ANNOTATIONS
118	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
119	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
120	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
121	select ARCH_WANTS_NO_INSTR
122	select ARCH_WANT_GENERAL_HUGETLB
123	select ARCH_WANT_HUGE_PMD_SHARE
124	select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP	if X86_64
125	select ARCH_WANT_LD_ORPHAN_WARN
126	select ARCH_WANTS_THP_SWAP		if X86_64
127	select ARCH_HAS_PARANOID_L1D_FLUSH
128	select BUILDTIME_TABLE_SORT
129	select CLKEVT_I8253
130	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
131	select CLOCKSOURCE_WATCHDOG
132	select DCACHE_WORD_ACCESS
133	select DYNAMIC_SIGFRAME
134	select EDAC_ATOMIC_SCRUB
135	select EDAC_SUPPORT
136	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
137	select GENERIC_CLOCKEVENTS_MIN_ADJUST
138	select GENERIC_CMOS_UPDATE
139	select GENERIC_CPU_AUTOPROBE
140	select GENERIC_CPU_VULNERABILITIES
141	select GENERIC_EARLY_IOREMAP
142	select GENERIC_ENTRY
143	select GENERIC_IOMAP
144	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
145	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
146	select GENERIC_IRQ_MIGRATION		if SMP
147	select GENERIC_IRQ_PROBE
148	select GENERIC_IRQ_RESERVATION_MODE
149	select GENERIC_IRQ_SHOW
150	select GENERIC_PENDING_IRQ		if SMP
151	select GENERIC_PTDUMP
152	select GENERIC_SMP_IDLE_THREAD
153	select GENERIC_TIME_VSYSCALL
154	select GENERIC_GETTIMEOFDAY
155	select GENERIC_VDSO_TIME_NS
156	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
157	select HARDIRQS_SW_RESEND
158	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
159	select HAVE_ACPI_APEI			if ACPI
160	select HAVE_ACPI_APEI_NMI		if ACPI
161	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
162	select HAVE_ARCH_AUDITSYSCALL
163	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
164	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
165	select HAVE_ARCH_JUMP_LABEL
166	select HAVE_ARCH_JUMP_LABEL_RELATIVE
167	select HAVE_ARCH_KASAN			if X86_64
168	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
169	select HAVE_ARCH_KFENCE
170	select HAVE_ARCH_KGDB
171	select HAVE_ARCH_MMAP_RND_BITS		if MMU
172	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
173	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
174	select HAVE_ARCH_PREL32_RELOCATIONS
175	select HAVE_ARCH_SECCOMP_FILTER
176	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
177	select HAVE_ARCH_STACKLEAK
178	select HAVE_ARCH_TRACEHOOK
179	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
180	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
181	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
182	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
183	select HAVE_ARCH_VMAP_STACK		if X86_64
184	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
185	select HAVE_ARCH_WITHIN_STACK_FRAMES
186	select HAVE_ASM_MODVERSIONS
187	select HAVE_CMPXCHG_DOUBLE
188	select HAVE_CMPXCHG_LOCAL
189	select HAVE_CONTEXT_TRACKING		if X86_64
190	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
191	select HAVE_C_RECORDMCOUNT
192	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
193	select HAVE_BUILDTIME_MCOUNT_SORT
194	select HAVE_DEBUG_KMEMLEAK
195	select HAVE_DMA_CONTIGUOUS
196	select HAVE_DYNAMIC_FTRACE
197	select HAVE_DYNAMIC_FTRACE_WITH_REGS
198	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
199	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
200	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
201	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
202	select HAVE_EBPF_JIT
203	select HAVE_EFFICIENT_UNALIGNED_ACCESS
204	select HAVE_EISA
205	select HAVE_EXIT_THREAD
206	select HAVE_FAST_GUP
207	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
208	select HAVE_FTRACE_MCOUNT_RECORD
209	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
210	select HAVE_FUNCTION_TRACER
211	select HAVE_GCC_PLUGINS
212	select HAVE_HW_BREAKPOINT
213	select HAVE_IOREMAP_PROT
214	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
215	select HAVE_IRQ_TIME_ACCOUNTING
216	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
217	select HAVE_KERNEL_BZIP2
218	select HAVE_KERNEL_GZIP
219	select HAVE_KERNEL_LZ4
220	select HAVE_KERNEL_LZMA
221	select HAVE_KERNEL_LZO
222	select HAVE_KERNEL_XZ
223	select HAVE_KERNEL_ZSTD
224	select HAVE_KPROBES
225	select HAVE_KPROBES_ON_FTRACE
226	select HAVE_FUNCTION_ERROR_INJECTION
227	select HAVE_KRETPROBES
228	select HAVE_RETHOOK
229	select HAVE_KVM
230	select HAVE_LIVEPATCH			if X86_64
231	select HAVE_MIXED_BREAKPOINTS_REGS
232	select HAVE_MOD_ARCH_SPECIFIC
233	select HAVE_MOVE_PMD
234	select HAVE_MOVE_PUD
235	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
236	select HAVE_NMI
237	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
238	select HAVE_OBJTOOL			if X86_64
239	select HAVE_OPTPROBES
240	select HAVE_PCSPKR_PLATFORM
241	select HAVE_PERF_EVENTS
242	select HAVE_PERF_EVENTS_NMI
243	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
244	select HAVE_PCI
245	select HAVE_PERF_REGS
246	select HAVE_PERF_USER_STACK_DUMP
247	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
248	select MMU_GATHER_MERGE_VMAS
249	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
250	select HAVE_REGS_AND_STACK_ACCESS_API
251	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
252	select HAVE_FUNCTION_ARG_ACCESS_API
253	select HAVE_SETUP_PER_CPU_AREA
254	select HAVE_SOFTIRQ_ON_OWN_STACK
255	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
256	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
257	select HAVE_STATIC_CALL
258	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
259	select HAVE_PREEMPT_DYNAMIC_CALL
260	select HAVE_RSEQ
261	select HAVE_SYSCALL_TRACEPOINTS
262	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
263	select HAVE_UNSTABLE_SCHED_CLOCK
264	select HAVE_USER_RETURN_NOTIFIER
265	select HAVE_GENERIC_VDSO
266	select HOTPLUG_SMT			if SMP
267	select IRQ_FORCED_THREADING
268	select NEED_PER_CPU_EMBED_FIRST_CHUNK
269	select NEED_PER_CPU_PAGE_FIRST_CHUNK
270	select NEED_SG_DMA_LENGTH
271	select PCI_DOMAINS			if PCI
272	select PCI_LOCKLESS_CONFIG		if PCI
273	select PERF_EVENTS
274	select RTC_LIB
275	select RTC_MC146818_LIB
276	select SPARSE_IRQ
277	select SRCU
278	select SYSCTL_EXCEPTION_TRACE
279	select THREAD_INFO_IN_TASK
280	select TRACE_IRQFLAGS_SUPPORT
281	select USER_STACKTRACE_SUPPORT
282	select VIRT_TO_BUS
283	select HAVE_ARCH_KCSAN			if X86_64
284	select X86_FEATURE_NAMES		if PROC_FS
285	select PROC_PID_ARCH_STATUS		if PROC_FS
286	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
287	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
288
289config INSTRUCTION_DECODER
290	def_bool y
291	depends on KPROBES || PERF_EVENTS || UPROBES
292
293config OUTPUT_FORMAT
294	string
295	default "elf32-i386" if X86_32
296	default "elf64-x86-64" if X86_64
297
298config LOCKDEP_SUPPORT
299	def_bool y
300
301config STACKTRACE_SUPPORT
302	def_bool y
303
304config MMU
305	def_bool y
306
307config ARCH_MMAP_RND_BITS_MIN
308	default 28 if 64BIT
309	default 8
310
311config ARCH_MMAP_RND_BITS_MAX
312	default 32 if 64BIT
313	default 16
314
315config ARCH_MMAP_RND_COMPAT_BITS_MIN
316	default 8
317
318config ARCH_MMAP_RND_COMPAT_BITS_MAX
319	default 16
320
321config SBUS
322	bool
323
324config GENERIC_ISA_DMA
325	def_bool y
326	depends on ISA_DMA_API
327
328config GENERIC_BUG
329	def_bool y
330	depends on BUG
331	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
332
333config GENERIC_BUG_RELATIVE_POINTERS
334	bool
335
336config ARCH_MAY_HAVE_PC_FDC
337	def_bool y
338	depends on ISA_DMA_API
339
340config GENERIC_CALIBRATE_DELAY
341	def_bool y
342
343config ARCH_HAS_CPU_RELAX
344	def_bool y
345
346config ARCH_HIBERNATION_POSSIBLE
347	def_bool y
348
349config ARCH_NR_GPIO
350	int
351	default 1024 if X86_64
352	default 512
353
354config ARCH_SUSPEND_POSSIBLE
355	def_bool y
356
357config AUDIT_ARCH
358	def_bool y if X86_64
359
360config KASAN_SHADOW_OFFSET
361	hex
362	depends on KASAN
363	default 0xdffffc0000000000
364
365config HAVE_INTEL_TXT
366	def_bool y
367	depends on INTEL_IOMMU && ACPI
368
369config X86_32_SMP
370	def_bool y
371	depends on X86_32 && SMP
372
373config X86_64_SMP
374	def_bool y
375	depends on X86_64 && SMP
376
377config ARCH_SUPPORTS_UPROBES
378	def_bool y
379
380config FIX_EARLYCON_MEM
381	def_bool y
382
383config DYNAMIC_PHYSICAL_MASK
384	bool
385
386config PGTABLE_LEVELS
387	int
388	default 5 if X86_5LEVEL
389	default 4 if X86_64
390	default 3 if X86_PAE
391	default 2
392
393config CC_HAS_SANE_STACKPROTECTOR
394	bool
395	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
396	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
397	help
398	  We have to make sure stack protector is unconditionally disabled if
399	  the compiler produces broken code or if it does not let us control
400	  the segment on 32-bit kernels.
401
402menu "Processor type and features"
403
404config SMP
405	bool "Symmetric multi-processing support"
406	help
407	  This enables support for systems with more than one CPU. If you have
408	  a system with only one CPU, say N. If you have a system with more
409	  than one CPU, say Y.
410
411	  If you say N here, the kernel will run on uni- and multiprocessor
412	  machines, but will use only one CPU of a multiprocessor machine. If
413	  you say Y here, the kernel will run on many, but not all,
414	  uniprocessor machines. On a uniprocessor machine, the kernel
415	  will run faster if you say N here.
416
417	  Note that if you say Y here and choose architecture "586" or
418	  "Pentium" under "Processor family", the kernel will not work on 486
419	  architectures. Similarly, multiprocessor kernels for the "PPro"
420	  architecture may not work on all Pentium based boards.
421
422	  People using multiprocessor machines who say Y here should also say
423	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
424	  Management" code will be disabled if you say Y here.
425
426	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
427	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
428	  <http://www.tldp.org/docs.html#howto>.
429
430	  If you don't know what to do here, say N.
431
432config X86_FEATURE_NAMES
433	bool "Processor feature human-readable names" if EMBEDDED
434	default y
435	help
436	  This option compiles in a table of x86 feature bits and corresponding
437	  names.  This is required to support /proc/cpuinfo and a few kernel
438	  messages.  You can disable this to save space, at the expense of
439	  making those few kernel messages show numeric feature bits instead.
440
441	  If in doubt, say Y.
442
443config X86_X2APIC
444	bool "Support x2apic"
445	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
446	help
447	  This enables x2apic support on CPUs that have this feature.
448
449	  This allows 32-bit apic IDs (so it can support very large systems),
450	  and accesses the local apic via MSRs not via mmio.
451
452	  If you don't know what to do here, say N.
453
454config X86_MPPARSE
455	bool "Enable MPS table" if ACPI
456	default y
457	depends on X86_LOCAL_APIC
458	help
459	  For old smp systems that do not have proper acpi support. Newer systems
460	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
461
462config GOLDFISH
463	def_bool y
464	depends on X86_GOLDFISH
465
466config X86_CPU_RESCTRL
467	bool "x86 CPU resource control support"
468	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
469	select KERNFS
470	select PROC_CPU_RESCTRL		if PROC_FS
471	help
472	  Enable x86 CPU resource control support.
473
474	  Provide support for the allocation and monitoring of system resources
475	  usage by the CPU.
476
477	  Intel calls this Intel Resource Director Technology
478	  (Intel(R) RDT). More information about RDT can be found in the
479	  Intel x86 Architecture Software Developer Manual.
480
481	  AMD calls this AMD Platform Quality of Service (AMD QoS).
482	  More information about AMD QoS can be found in the AMD64 Technology
483	  Platform Quality of Service Extensions manual.
484
485	  Say N if unsure.
486
487if X86_32
488config X86_BIGSMP
489	bool "Support for big SMP systems with more than 8 CPUs"
490	depends on SMP
491	help
492	  This option is needed for the systems that have more than 8 CPUs.
493
494config X86_EXTENDED_PLATFORM
495	bool "Support for extended (non-PC) x86 platforms"
496	default y
497	help
498	  If you disable this option then the kernel will only support
499	  standard PC platforms. (which covers the vast majority of
500	  systems out there.)
501
502	  If you enable this option then you'll be able to select support
503	  for the following (non-PC) 32 bit x86 platforms:
504		Goldfish (Android emulator)
505		AMD Elan
506		RDC R-321x SoC
507		SGI 320/540 (Visual Workstation)
508		STA2X11-based (e.g. Northville)
509		Moorestown MID devices
510
511	  If you have one of these systems, or if you want to build a
512	  generic distribution kernel, say Y here - otherwise say N.
513endif # X86_32
514
515if X86_64
516config X86_EXTENDED_PLATFORM
517	bool "Support for extended (non-PC) x86 platforms"
518	default y
519	help
520	  If you disable this option then the kernel will only support
521	  standard PC platforms. (which covers the vast majority of
522	  systems out there.)
523
524	  If you enable this option then you'll be able to select support
525	  for the following (non-PC) 64 bit x86 platforms:
526		Numascale NumaChip
527		ScaleMP vSMP
528		SGI Ultraviolet
529
530	  If you have one of these systems, or if you want to build a
531	  generic distribution kernel, say Y here - otherwise say N.
532endif # X86_64
533# This is an alphabetically sorted list of 64 bit extended platforms
534# Please maintain the alphabetic order if and when there are additions
535config X86_NUMACHIP
536	bool "Numascale NumaChip"
537	depends on X86_64
538	depends on X86_EXTENDED_PLATFORM
539	depends on NUMA
540	depends on SMP
541	depends on X86_X2APIC
542	depends on PCI_MMCONFIG
543	help
544	  Adds support for Numascale NumaChip large-SMP systems. Needed to
545	  enable more than ~168 cores.
546	  If you don't have one of these, you should say N here.
547
548config X86_VSMP
549	bool "ScaleMP vSMP"
550	select HYPERVISOR_GUEST
551	select PARAVIRT
552	depends on X86_64 && PCI
553	depends on X86_EXTENDED_PLATFORM
554	depends on SMP
555	help
556	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
557	  supposed to run on these EM64T-based machines.  Only choose this option
558	  if you have one of these machines.
559
560config X86_UV
561	bool "SGI Ultraviolet"
562	depends on X86_64
563	depends on X86_EXTENDED_PLATFORM
564	depends on NUMA
565	depends on EFI
566	depends on KEXEC_CORE
567	depends on X86_X2APIC
568	depends on PCI
569	help
570	  This option is needed in order to support SGI Ultraviolet systems.
571	  If you don't have one of these, you should say N here.
572
573# Following is an alphabetically sorted list of 32 bit extended platforms
574# Please maintain the alphabetic order if and when there are additions
575
576config X86_GOLDFISH
577	bool "Goldfish (Virtual Platform)"
578	depends on X86_EXTENDED_PLATFORM
579	help
580	  Enable support for the Goldfish virtual platform used primarily
581	  for Android development. Unless you are building for the Android
582	  Goldfish emulator say N here.
583
584config X86_INTEL_CE
585	bool "CE4100 TV platform"
586	depends on PCI
587	depends on PCI_GODIRECT
588	depends on X86_IO_APIC
589	depends on X86_32
590	depends on X86_EXTENDED_PLATFORM
591	select X86_REBOOTFIXUPS
592	select OF
593	select OF_EARLY_FLATTREE
594	help
595	  Select for the Intel CE media processor (CE4100) SOC.
596	  This option compiles in support for the CE4100 SOC for settop
597	  boxes and media devices.
598
599config X86_INTEL_MID
600	bool "Intel MID platform support"
601	depends on X86_EXTENDED_PLATFORM
602	depends on X86_PLATFORM_DEVICES
603	depends on PCI
604	depends on X86_64 || (PCI_GOANY && X86_32)
605	depends on X86_IO_APIC
606	select I2C
607	select DW_APB_TIMER
608	select INTEL_SCU_PCI
609	help
610	  Select to build a kernel capable of supporting Intel MID (Mobile
611	  Internet Device) platform systems which do not have the PCI legacy
612	  interfaces. If you are building for a PC class system say N here.
613
614	  Intel MID platforms are based on an Intel processor and chipset which
615	  consume less power than most of the x86 derivatives.
616
617config X86_INTEL_QUARK
618	bool "Intel Quark platform support"
619	depends on X86_32
620	depends on X86_EXTENDED_PLATFORM
621	depends on X86_PLATFORM_DEVICES
622	depends on X86_TSC
623	depends on PCI
624	depends on PCI_GOANY
625	depends on X86_IO_APIC
626	select IOSF_MBI
627	select INTEL_IMR
628	select COMMON_CLK
629	help
630	  Select to include support for Quark X1000 SoC.
631	  Say Y here if you have a Quark based system such as the Arduino
632	  compatible Intel Galileo.
633
634config X86_INTEL_LPSS
635	bool "Intel Low Power Subsystem Support"
636	depends on X86 && ACPI && PCI
637	select COMMON_CLK
638	select PINCTRL
639	select IOSF_MBI
640	help
641	  Select to build support for Intel Low Power Subsystem such as
642	  found on Intel Lynxpoint PCH. Selecting this option enables
643	  things like clock tree (common clock framework) and pincontrol
644	  which are needed by the LPSS peripheral drivers.
645
646config X86_AMD_PLATFORM_DEVICE
647	bool "AMD ACPI2Platform devices support"
648	depends on ACPI
649	select COMMON_CLK
650	select PINCTRL
651	help
652	  Select to interpret AMD specific ACPI device to platform device
653	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
654	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
655	  implemented under PINCTRL subsystem.
656
657config IOSF_MBI
658	tristate "Intel SoC IOSF Sideband support for SoC platforms"
659	depends on PCI
660	help
661	  This option enables sideband register access support for Intel SoC
662	  platforms. On these platforms the IOSF sideband is used in lieu of
663	  MSR's for some register accesses, mostly but not limited to thermal
664	  and power. Drivers may query the availability of this device to
665	  determine if they need the sideband in order to work on these
666	  platforms. The sideband is available on the following SoC products.
667	  This list is not meant to be exclusive.
668	   - BayTrail
669	   - Braswell
670	   - Quark
671
672	  You should say Y if you are running a kernel on one of these SoC's.
673
674config IOSF_MBI_DEBUG
675	bool "Enable IOSF sideband access through debugfs"
676	depends on IOSF_MBI && DEBUG_FS
677	help
678	  Select this option to expose the IOSF sideband access registers (MCR,
679	  MDR, MCRX) through debugfs to write and read register information from
680	  different units on the SoC. This is most useful for obtaining device
681	  state information for debug and analysis. As this is a general access
682	  mechanism, users of this option would have specific knowledge of the
683	  device they want to access.
684
685	  If you don't require the option or are in doubt, say N.
686
687config X86_RDC321X
688	bool "RDC R-321x SoC"
689	depends on X86_32
690	depends on X86_EXTENDED_PLATFORM
691	select M486
692	select X86_REBOOTFIXUPS
693	help
694	  This option is needed for RDC R-321x system-on-chip, also known
695	  as R-8610-(G).
696	  If you don't have one of these chips, you should say N here.
697
698config X86_32_NON_STANDARD
699	bool "Support non-standard 32-bit SMP architectures"
700	depends on X86_32 && SMP
701	depends on X86_EXTENDED_PLATFORM
702	help
703	  This option compiles in the bigsmp and STA2X11 default
704	  subarchitectures.  It is intended for a generic binary
705	  kernel. If you select them all, kernel will probe it one by
706	  one and will fallback to default.
707
708# Alphabetically sorted list of Non standard 32 bit platforms
709
710config X86_SUPPORTS_MEMORY_FAILURE
711	def_bool y
712	# MCE code calls memory_failure():
713	depends on X86_MCE
714	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
715	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
716	depends on X86_64 || !SPARSEMEM
717	select ARCH_SUPPORTS_MEMORY_FAILURE
718
719config STA2X11
720	bool "STA2X11 Companion Chip Support"
721	depends on X86_32_NON_STANDARD && PCI
722	select SWIOTLB
723	select MFD_STA2X11
724	select GPIOLIB
725	help
726	  This adds support for boards based on the STA2X11 IO-Hub,
727	  a.k.a. "ConneXt". The chip is used in place of the standard
728	  PC chipset, so all "standard" peripherals are missing. If this
729	  option is selected the kernel will still be able to boot on
730	  standard PC machines.
731
732config X86_32_IRIS
733	tristate "Eurobraille/Iris poweroff module"
734	depends on X86_32
735	help
736	  The Iris machines from EuroBraille do not have APM or ACPI support
737	  to shut themselves down properly.  A special I/O sequence is
738	  needed to do so, which is what this module does at
739	  kernel shutdown.
740
741	  This is only for Iris machines from EuroBraille.
742
743	  If unused, say N.
744
745config SCHED_OMIT_FRAME_POINTER
746	def_bool y
747	prompt "Single-depth WCHAN output"
748	depends on X86
749	help
750	  Calculate simpler /proc/<PID>/wchan values. If this option
751	  is disabled then wchan values will recurse back to the
752	  caller function. This provides more accurate wchan values,
753	  at the expense of slightly more scheduling overhead.
754
755	  If in doubt, say "Y".
756
757menuconfig HYPERVISOR_GUEST
758	bool "Linux guest support"
759	help
760	  Say Y here to enable options for running Linux under various hyper-
761	  visors. This option enables basic hypervisor detection and platform
762	  setup.
763
764	  If you say N, all options in this submenu will be skipped and
765	  disabled, and Linux guest support won't be built in.
766
767if HYPERVISOR_GUEST
768
769config PARAVIRT
770	bool "Enable paravirtualization code"
771	depends on HAVE_STATIC_CALL
772	help
773	  This changes the kernel so it can modify itself when it is run
774	  under a hypervisor, potentially improving performance significantly
775	  over full virtualization.  However, when run without a hypervisor
776	  the kernel is theoretically slower and slightly larger.
777
778config PARAVIRT_XXL
779	bool
780
781config PARAVIRT_DEBUG
782	bool "paravirt-ops debugging"
783	depends on PARAVIRT && DEBUG_KERNEL
784	help
785	  Enable to debug paravirt_ops internals.  Specifically, BUG if
786	  a paravirt_op is missing when it is called.
787
788config PARAVIRT_SPINLOCKS
789	bool "Paravirtualization layer for spinlocks"
790	depends on PARAVIRT && SMP
791	help
792	  Paravirtualized spinlocks allow a pvops backend to replace the
793	  spinlock implementation with something virtualization-friendly
794	  (for example, block the virtual CPU rather than spinning).
795
796	  It has a minimal impact on native kernels and gives a nice performance
797	  benefit on paravirtualized KVM / Xen kernels.
798
799	  If you are unsure how to answer this question, answer Y.
800
801config X86_HV_CALLBACK_VECTOR
802	def_bool n
803
804source "arch/x86/xen/Kconfig"
805
806config KVM_GUEST
807	bool "KVM Guest support (including kvmclock)"
808	depends on PARAVIRT
809	select PARAVIRT_CLOCK
810	select ARCH_CPUIDLE_HALTPOLL
811	select X86_HV_CALLBACK_VECTOR
812	default y
813	help
814	  This option enables various optimizations for running under the KVM
815	  hypervisor. It includes a paravirtualized clock, so that instead
816	  of relying on a PIT (or probably other) emulation by the
817	  underlying device model, the host provides the guest with
818	  timing infrastructure such as time of day, and system time
819
820config ARCH_CPUIDLE_HALTPOLL
821	def_bool n
822	prompt "Disable host haltpoll when loading haltpoll driver"
823	help
824	  If virtualized under KVM, disable host haltpoll.
825
826config PVH
827	bool "Support for running PVH guests"
828	help
829	  This option enables the PVH entry point for guest virtual machines
830	  as specified in the x86/HVM direct boot ABI.
831
832config PARAVIRT_TIME_ACCOUNTING
833	bool "Paravirtual steal time accounting"
834	depends on PARAVIRT
835	help
836	  Select this option to enable fine granularity task steal time
837	  accounting. Time spent executing other tasks in parallel with
838	  the current vCPU is discounted from the vCPU power. To account for
839	  that, there can be a small performance impact.
840
841	  If in doubt, say N here.
842
843config PARAVIRT_CLOCK
844	bool
845
846config JAILHOUSE_GUEST
847	bool "Jailhouse non-root cell support"
848	depends on X86_64 && PCI
849	select X86_PM_TIMER
850	help
851	  This option allows to run Linux as guest in a Jailhouse non-root
852	  cell. You can leave this option disabled if you only want to start
853	  Jailhouse and run Linux afterwards in the root cell.
854
855config ACRN_GUEST
856	bool "ACRN Guest support"
857	depends on X86_64
858	select X86_HV_CALLBACK_VECTOR
859	help
860	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
861	  a flexible, lightweight reference open-source hypervisor, built with
862	  real-time and safety-criticality in mind. It is built for embedded
863	  IOT with small footprint and real-time features. More details can be
864	  found in https://projectacrn.org/.
865
866config INTEL_TDX_GUEST
867	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
868	depends on X86_64 && CPU_SUP_INTEL
869	depends on X86_X2APIC
870	select ARCH_HAS_CC_PLATFORM
871	select X86_MEM_ENCRYPT
872	select X86_MCE
873	help
874	  Support running as a guest under Intel TDX.  Without this support,
875	  the guest kernel can not boot or run under TDX.
876	  TDX includes memory encryption and integrity capabilities
877	  which protect the confidentiality and integrity of guest
878	  memory contents and CPU state. TDX guests are protected from
879	  some attacks from the VMM.
880
881endif # HYPERVISOR_GUEST
882
883source "arch/x86/Kconfig.cpu"
884
885config HPET_TIMER
886	def_bool X86_64
887	prompt "HPET Timer Support" if X86_32
888	help
889	  Use the IA-PC HPET (High Precision Event Timer) to manage
890	  time in preference to the PIT and RTC, if a HPET is
891	  present.
892	  HPET is the next generation timer replacing legacy 8254s.
893	  The HPET provides a stable time base on SMP
894	  systems, unlike the TSC, but it is more expensive to access,
895	  as it is off-chip.  The interface used is documented
896	  in the HPET spec, revision 1.
897
898	  You can safely choose Y here.  However, HPET will only be
899	  activated if the platform and the BIOS support this feature.
900	  Otherwise the 8254 will be used for timing services.
901
902	  Choose N to continue using the legacy 8254 timer.
903
904config HPET_EMULATE_RTC
905	def_bool y
906	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
907
908# Mark as expert because too many people got it wrong.
909# The code disables itself when not needed.
910config DMI
911	default y
912	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
913	bool "Enable DMI scanning" if EXPERT
914	help
915	  Enabled scanning of DMI to identify machine quirks. Say Y
916	  here unless you have verified that your setup is not
917	  affected by entries in the DMI blacklist. Required by PNP
918	  BIOS code.
919
920config GART_IOMMU
921	bool "Old AMD GART IOMMU support"
922	select DMA_OPS
923	select IOMMU_HELPER
924	select SWIOTLB
925	depends on X86_64 && PCI && AMD_NB
926	help
927	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
928	  GART based hardware IOMMUs.
929
930	  The GART supports full DMA access for devices with 32-bit access
931	  limitations, on systems with more than 3 GB. This is usually needed
932	  for USB, sound, many IDE/SATA chipsets and some other devices.
933
934	  Newer systems typically have a modern AMD IOMMU, supported via
935	  the CONFIG_AMD_IOMMU=y config option.
936
937	  In normal configurations this driver is only active when needed:
938	  there's more than 3 GB of memory and the system contains a
939	  32-bit limited device.
940
941	  If unsure, say Y.
942
943config BOOT_VESA_SUPPORT
944	bool
945	help
946	  If true, at least one selected framebuffer driver can take advantage
947	  of VESA video modes set at an early boot stage via the vga= parameter.
948
949config MAXSMP
950	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
951	depends on X86_64 && SMP && DEBUG_KERNEL
952	select CPUMASK_OFFSTACK
953	help
954	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
955	  If unsure, say N.
956
957#
958# The maximum number of CPUs supported:
959#
960# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
961# and which can be configured interactively in the
962# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
963#
964# The ranges are different on 32-bit and 64-bit kernels, depending on
965# hardware capabilities and scalability features of the kernel.
966#
967# ( If MAXSMP is enabled we just use the highest possible value and disable
968#   interactive configuration. )
969#
970
971config NR_CPUS_RANGE_BEGIN
972	int
973	default NR_CPUS_RANGE_END if MAXSMP
974	default    1 if !SMP
975	default    2
976
977config NR_CPUS_RANGE_END
978	int
979	depends on X86_32
980	default   64 if  SMP &&  X86_BIGSMP
981	default    8 if  SMP && !X86_BIGSMP
982	default    1 if !SMP
983
984config NR_CPUS_RANGE_END
985	int
986	depends on X86_64
987	default 8192 if  SMP && CPUMASK_OFFSTACK
988	default  512 if  SMP && !CPUMASK_OFFSTACK
989	default    1 if !SMP
990
991config NR_CPUS_DEFAULT
992	int
993	depends on X86_32
994	default   32 if  X86_BIGSMP
995	default    8 if  SMP
996	default    1 if !SMP
997
998config NR_CPUS_DEFAULT
999	int
1000	depends on X86_64
1001	default 8192 if  MAXSMP
1002	default   64 if  SMP
1003	default    1 if !SMP
1004
1005config NR_CPUS
1006	int "Maximum number of CPUs" if SMP && !MAXSMP
1007	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1008	default NR_CPUS_DEFAULT
1009	help
1010	  This allows you to specify the maximum number of CPUs which this
1011	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1012	  supported value is 8192, otherwise the maximum value is 512.  The
1013	  minimum value which makes sense is 2.
1014
1015	  This is purely to save memory: each supported CPU adds about 8KB
1016	  to the kernel image.
1017
1018config SCHED_CLUSTER
1019	bool "Cluster scheduler support"
1020	depends on SMP
1021	default y
1022	help
1023	  Cluster scheduler support improves the CPU scheduler's decision
1024	  making when dealing with machines that have clusters of CPUs.
1025	  Cluster usually means a couple of CPUs which are placed closely
1026	  by sharing mid-level caches, last-level cache tags or internal
1027	  busses.
1028
1029config SCHED_SMT
1030	def_bool y if SMP
1031
1032config SCHED_MC
1033	def_bool y
1034	prompt "Multi-core scheduler support"
1035	depends on SMP
1036	help
1037	  Multi-core scheduler support improves the CPU scheduler's decision
1038	  making when dealing with multi-core CPU chips at a cost of slightly
1039	  increased overhead in some places. If unsure say N here.
1040
1041config SCHED_MC_PRIO
1042	bool "CPU core priorities scheduler support"
1043	depends on SCHED_MC && CPU_SUP_INTEL
1044	select X86_INTEL_PSTATE
1045	select CPU_FREQ
1046	default y
1047	help
1048	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1049	  core ordering determined at manufacturing time, which allows
1050	  certain cores to reach higher turbo frequencies (when running
1051	  single threaded workloads) than others.
1052
1053	  Enabling this kernel feature teaches the scheduler about
1054	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1055	  scheduler's CPU selection logic accordingly, so that higher
1056	  overall system performance can be achieved.
1057
1058	  This feature will have no effect on CPUs without this feature.
1059
1060	  If unsure say Y here.
1061
1062config UP_LATE_INIT
1063	def_bool y
1064	depends on !SMP && X86_LOCAL_APIC
1065
1066config X86_UP_APIC
1067	bool "Local APIC support on uniprocessors" if !PCI_MSI
1068	default PCI_MSI
1069	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1070	help
1071	  A local APIC (Advanced Programmable Interrupt Controller) is an
1072	  integrated interrupt controller in the CPU. If you have a single-CPU
1073	  system which has a processor with a local APIC, you can say Y here to
1074	  enable and use it. If you say Y here even though your machine doesn't
1075	  have a local APIC, then the kernel will still run with no slowdown at
1076	  all. The local APIC supports CPU-generated self-interrupts (timer,
1077	  performance counters), and the NMI watchdog which detects hard
1078	  lockups.
1079
1080config X86_UP_IOAPIC
1081	bool "IO-APIC support on uniprocessors"
1082	depends on X86_UP_APIC
1083	help
1084	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1085	  SMP-capable replacement for PC-style interrupt controllers. Most
1086	  SMP systems and many recent uniprocessor systems have one.
1087
1088	  If you have a single-CPU system with an IO-APIC, you can say Y here
1089	  to use it. If you say Y here even though your machine doesn't have
1090	  an IO-APIC, then the kernel will still run with no slowdown at all.
1091
1092config X86_LOCAL_APIC
1093	def_bool y
1094	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1095	select IRQ_DOMAIN_HIERARCHY
1096	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1097
1098config X86_IO_APIC
1099	def_bool y
1100	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1101
1102config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1103	bool "Reroute for broken boot IRQs"
1104	depends on X86_IO_APIC
1105	help
1106	  This option enables a workaround that fixes a source of
1107	  spurious interrupts. This is recommended when threaded
1108	  interrupt handling is used on systems where the generation of
1109	  superfluous "boot interrupts" cannot be disabled.
1110
1111	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1112	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1113	  kernel does during interrupt handling). On chipsets where this
1114	  boot IRQ generation cannot be disabled, this workaround keeps
1115	  the original IRQ line masked so that only the equivalent "boot
1116	  IRQ" is delivered to the CPUs. The workaround also tells the
1117	  kernel to set up the IRQ handler on the boot IRQ line. In this
1118	  way only one interrupt is delivered to the kernel. Otherwise
1119	  the spurious second interrupt may cause the kernel to bring
1120	  down (vital) interrupt lines.
1121
1122	  Only affects "broken" chipsets. Interrupt sharing may be
1123	  increased on these systems.
1124
1125config X86_MCE
1126	bool "Machine Check / overheating reporting"
1127	select GENERIC_ALLOCATOR
1128	default y
1129	help
1130	  Machine Check support allows the processor to notify the
1131	  kernel if it detects a problem (e.g. overheating, data corruption).
1132	  The action the kernel takes depends on the severity of the problem,
1133	  ranging from warning messages to halting the machine.
1134
1135config X86_MCELOG_LEGACY
1136	bool "Support for deprecated /dev/mcelog character device"
1137	depends on X86_MCE
1138	help
1139	  Enable support for /dev/mcelog which is needed by the old mcelog
1140	  userspace logging daemon. Consider switching to the new generation
1141	  rasdaemon solution.
1142
1143config X86_MCE_INTEL
1144	def_bool y
1145	prompt "Intel MCE features"
1146	depends on X86_MCE && X86_LOCAL_APIC
1147	help
1148	  Additional support for intel specific MCE features such as
1149	  the thermal monitor.
1150
1151config X86_MCE_AMD
1152	def_bool y
1153	prompt "AMD MCE features"
1154	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1155	help
1156	  Additional support for AMD specific MCE features such as
1157	  the DRAM Error Threshold.
1158
1159config X86_ANCIENT_MCE
1160	bool "Support for old Pentium 5 / WinChip machine checks"
1161	depends on X86_32 && X86_MCE
1162	help
1163	  Include support for machine check handling on old Pentium 5 or WinChip
1164	  systems. These typically need to be enabled explicitly on the command
1165	  line.
1166
1167config X86_MCE_THRESHOLD
1168	depends on X86_MCE_AMD || X86_MCE_INTEL
1169	def_bool y
1170
1171config X86_MCE_INJECT
1172	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1173	tristate "Machine check injector support"
1174	help
1175	  Provide support for injecting machine checks for testing purposes.
1176	  If you don't know what a machine check is and you don't do kernel
1177	  QA it is safe to say n.
1178
1179source "arch/x86/events/Kconfig"
1180
1181config X86_LEGACY_VM86
1182	bool "Legacy VM86 support"
1183	depends on X86_32
1184	help
1185	  This option allows user programs to put the CPU into V8086
1186	  mode, which is an 80286-era approximation of 16-bit real mode.
1187
1188	  Some very old versions of X and/or vbetool require this option
1189	  for user mode setting.  Similarly, DOSEMU will use it if
1190	  available to accelerate real mode DOS programs.  However, any
1191	  recent version of DOSEMU, X, or vbetool should be fully
1192	  functional even without kernel VM86 support, as they will all
1193	  fall back to software emulation. Nevertheless, if you are using
1194	  a 16-bit DOS program where 16-bit performance matters, vm86
1195	  mode might be faster than emulation and you might want to
1196	  enable this option.
1197
1198	  Note that any app that works on a 64-bit kernel is unlikely to
1199	  need this option, as 64-bit kernels don't, and can't, support
1200	  V8086 mode. This option is also unrelated to 16-bit protected
1201	  mode and is not needed to run most 16-bit programs under Wine.
1202
1203	  Enabling this option increases the complexity of the kernel
1204	  and slows down exception handling a tiny bit.
1205
1206	  If unsure, say N here.
1207
1208config VM86
1209	bool
1210	default X86_LEGACY_VM86
1211
1212config X86_16BIT
1213	bool "Enable support for 16-bit segments" if EXPERT
1214	default y
1215	depends on MODIFY_LDT_SYSCALL
1216	help
1217	  This option is required by programs like Wine to run 16-bit
1218	  protected mode legacy code on x86 processors.  Disabling
1219	  this option saves about 300 bytes on i386, or around 6K text
1220	  plus 16K runtime memory on x86-64,
1221
1222config X86_ESPFIX32
1223	def_bool y
1224	depends on X86_16BIT && X86_32
1225
1226config X86_ESPFIX64
1227	def_bool y
1228	depends on X86_16BIT && X86_64
1229
1230config X86_VSYSCALL_EMULATION
1231	bool "Enable vsyscall emulation" if EXPERT
1232	default y
1233	depends on X86_64
1234	help
1235	  This enables emulation of the legacy vsyscall page.  Disabling
1236	  it is roughly equivalent to booting with vsyscall=none, except
1237	  that it will also disable the helpful warning if a program
1238	  tries to use a vsyscall.  With this option set to N, offending
1239	  programs will just segfault, citing addresses of the form
1240	  0xffffffffff600?00.
1241
1242	  This option is required by many programs built before 2013, and
1243	  care should be used even with newer programs if set to N.
1244
1245	  Disabling this option saves about 7K of kernel size and
1246	  possibly 4K of additional runtime pagetable memory.
1247
1248config X86_IOPL_IOPERM
1249	bool "IOPERM and IOPL Emulation"
1250	default y
1251	help
1252	  This enables the ioperm() and iopl() syscalls which are necessary
1253	  for legacy applications.
1254
1255	  Legacy IOPL support is an overbroad mechanism which allows user
1256	  space aside of accessing all 65536 I/O ports also to disable
1257	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1258	  capabilities and permission from potentially active security
1259	  modules.
1260
1261	  The emulation restricts the functionality of the syscall to
1262	  only allowing the full range I/O port access, but prevents the
1263	  ability to disable interrupts from user space which would be
1264	  granted if the hardware IOPL mechanism would be used.
1265
1266config TOSHIBA
1267	tristate "Toshiba Laptop support"
1268	depends on X86_32
1269	help
1270	  This adds a driver to safely access the System Management Mode of
1271	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1272	  not work on models with a Phoenix BIOS. The System Management Mode
1273	  is used to set the BIOS and power saving options on Toshiba portables.
1274
1275	  For information on utilities to make use of this driver see the
1276	  Toshiba Linux utilities web site at:
1277	  <http://www.buzzard.org.uk/toshiba/>.
1278
1279	  Say Y if you intend to run this kernel on a Toshiba portable.
1280	  Say N otherwise.
1281
1282config X86_REBOOTFIXUPS
1283	bool "Enable X86 board specific fixups for reboot"
1284	depends on X86_32
1285	help
1286	  This enables chipset and/or board specific fixups to be done
1287	  in order to get reboot to work correctly. This is only needed on
1288	  some combinations of hardware and BIOS. The symptom, for which
1289	  this config is intended, is when reboot ends with a stalled/hung
1290	  system.
1291
1292	  Currently, the only fixup is for the Geode machines using
1293	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1294
1295	  Say Y if you want to enable the fixup. Currently, it's safe to
1296	  enable this option even if you don't need it.
1297	  Say N otherwise.
1298
1299config MICROCODE
1300	bool "CPU microcode loading support"
1301	default y
1302	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1303	help
1304	  If you say Y here, you will be able to update the microcode on
1305	  Intel and AMD processors. The Intel support is for the IA32 family,
1306	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1307	  AMD support is for families 0x10 and later. You will obviously need
1308	  the actual microcode binary data itself which is not shipped with
1309	  the Linux kernel.
1310
1311	  The preferred method to load microcode from a detached initrd is described
1312	  in Documentation/x86/microcode.rst. For that you need to enable
1313	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1314	  initrd for microcode blobs.
1315
1316	  In addition, you can build the microcode into the kernel. For that you
1317	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1318	  config option.
1319
1320config MICROCODE_INTEL
1321	bool "Intel microcode loading support"
1322	depends on CPU_SUP_INTEL && MICROCODE
1323	default MICROCODE
1324	help
1325	  This options enables microcode patch loading support for Intel
1326	  processors.
1327
1328	  For the current Intel microcode data package go to
1329	  <https://downloadcenter.intel.com> and search for
1330	  'Linux Processor Microcode Data File'.
1331
1332config MICROCODE_AMD
1333	bool "AMD microcode loading support"
1334	depends on CPU_SUP_AMD && MICROCODE
1335	help
1336	  If you select this option, microcode patch loading support for AMD
1337	  processors will be enabled.
1338
1339config MICROCODE_LATE_LOADING
1340	bool "Late microcode loading (DANGEROUS)"
1341	default n
1342	depends on MICROCODE
1343	help
1344	  Loading microcode late, when the system is up and executing instructions
1345	  is a tricky business and should be avoided if possible. Just the sequence
1346	  of synchronizing all cores and SMT threads is one fragile dance which does
1347	  not guarantee that cores might not softlock after the loading. Therefore,
1348	  use this at your own risk. Late loading taints the kernel too.
1349
1350config X86_MSR
1351	tristate "/dev/cpu/*/msr - Model-specific register support"
1352	help
1353	  This device gives privileged processes access to the x86
1354	  Model-Specific Registers (MSRs).  It is a character device with
1355	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1356	  MSR accesses are directed to a specific CPU on multi-processor
1357	  systems.
1358
1359config X86_CPUID
1360	tristate "/dev/cpu/*/cpuid - CPU information support"
1361	help
1362	  This device gives processes access to the x86 CPUID instruction to
1363	  be executed on a specific processor.  It is a character device
1364	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1365	  /dev/cpu/31/cpuid.
1366
1367choice
1368	prompt "High Memory Support"
1369	default HIGHMEM4G
1370	depends on X86_32
1371
1372config NOHIGHMEM
1373	bool "off"
1374	help
1375	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1376	  However, the address space of 32-bit x86 processors is only 4
1377	  Gigabytes large. That means that, if you have a large amount of
1378	  physical memory, not all of it can be "permanently mapped" by the
1379	  kernel. The physical memory that's not permanently mapped is called
1380	  "high memory".
1381
1382	  If you are compiling a kernel which will never run on a machine with
1383	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1384	  choice and suitable for most users). This will result in a "3GB/1GB"
1385	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1386	  space and the remaining part of the 4GB virtual memory space is used
1387	  by the kernel to permanently map as much physical memory as
1388	  possible.
1389
1390	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1391	  answer "4GB" here.
1392
1393	  If more than 4 Gigabytes is used then answer "64GB" here. This
1394	  selection turns Intel PAE (Physical Address Extension) mode on.
1395	  PAE implements 3-level paging on IA32 processors. PAE is fully
1396	  supported by Linux, PAE mode is implemented on all recent Intel
1397	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1398	  then the kernel will not boot on CPUs that don't support PAE!
1399
1400	  The actual amount of total physical memory will either be
1401	  auto detected or can be forced by using a kernel command line option
1402	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1403	  your boot loader (lilo or loadlin) about how to pass options to the
1404	  kernel at boot time.)
1405
1406	  If unsure, say "off".
1407
1408config HIGHMEM4G
1409	bool "4GB"
1410	help
1411	  Select this if you have a 32-bit processor and between 1 and 4
1412	  gigabytes of physical RAM.
1413
1414config HIGHMEM64G
1415	bool "64GB"
1416	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1417	select X86_PAE
1418	help
1419	  Select this if you have a 32-bit processor and more than 4
1420	  gigabytes of physical RAM.
1421
1422endchoice
1423
1424choice
1425	prompt "Memory split" if EXPERT
1426	default VMSPLIT_3G
1427	depends on X86_32
1428	help
1429	  Select the desired split between kernel and user memory.
1430
1431	  If the address range available to the kernel is less than the
1432	  physical memory installed, the remaining memory will be available
1433	  as "high memory". Accessing high memory is a little more costly
1434	  than low memory, as it needs to be mapped into the kernel first.
1435	  Note that increasing the kernel address space limits the range
1436	  available to user programs, making the address space there
1437	  tighter.  Selecting anything other than the default 3G/1G split
1438	  will also likely make your kernel incompatible with binary-only
1439	  kernel modules.
1440
1441	  If you are not absolutely sure what you are doing, leave this
1442	  option alone!
1443
1444	config VMSPLIT_3G
1445		bool "3G/1G user/kernel split"
1446	config VMSPLIT_3G_OPT
1447		depends on !X86_PAE
1448		bool "3G/1G user/kernel split (for full 1G low memory)"
1449	config VMSPLIT_2G
1450		bool "2G/2G user/kernel split"
1451	config VMSPLIT_2G_OPT
1452		depends on !X86_PAE
1453		bool "2G/2G user/kernel split (for full 2G low memory)"
1454	config VMSPLIT_1G
1455		bool "1G/3G user/kernel split"
1456endchoice
1457
1458config PAGE_OFFSET
1459	hex
1460	default 0xB0000000 if VMSPLIT_3G_OPT
1461	default 0x80000000 if VMSPLIT_2G
1462	default 0x78000000 if VMSPLIT_2G_OPT
1463	default 0x40000000 if VMSPLIT_1G
1464	default 0xC0000000
1465	depends on X86_32
1466
1467config HIGHMEM
1468	def_bool y
1469	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1470
1471config X86_PAE
1472	bool "PAE (Physical Address Extension) Support"
1473	depends on X86_32 && !HIGHMEM4G
1474	select PHYS_ADDR_T_64BIT
1475	select SWIOTLB
1476	help
1477	  PAE is required for NX support, and furthermore enables
1478	  larger swapspace support for non-overcommit purposes. It
1479	  has the cost of more pagetable lookup overhead, and also
1480	  consumes more pagetable space per process.
1481
1482config X86_5LEVEL
1483	bool "Enable 5-level page tables support"
1484	default y
1485	select DYNAMIC_MEMORY_LAYOUT
1486	select SPARSEMEM_VMEMMAP
1487	depends on X86_64
1488	help
1489	  5-level paging enables access to larger address space:
1490	  upto 128 PiB of virtual address space and 4 PiB of
1491	  physical address space.
1492
1493	  It will be supported by future Intel CPUs.
1494
1495	  A kernel with the option enabled can be booted on machines that
1496	  support 4- or 5-level paging.
1497
1498	  See Documentation/x86/x86_64/5level-paging.rst for more
1499	  information.
1500
1501	  Say N if unsure.
1502
1503config X86_DIRECT_GBPAGES
1504	def_bool y
1505	depends on X86_64
1506	help
1507	  Certain kernel features effectively disable kernel
1508	  linear 1 GB mappings (even if the CPU otherwise
1509	  supports them), so don't confuse the user by printing
1510	  that we have them enabled.
1511
1512config X86_CPA_STATISTICS
1513	bool "Enable statistic for Change Page Attribute"
1514	depends on DEBUG_FS
1515	help
1516	  Expose statistics about the Change Page Attribute mechanism, which
1517	  helps to determine the effectiveness of preserving large and huge
1518	  page mappings when mapping protections are changed.
1519
1520config X86_MEM_ENCRYPT
1521	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1522	select DYNAMIC_PHYSICAL_MASK
1523	def_bool n
1524
1525config AMD_MEM_ENCRYPT
1526	bool "AMD Secure Memory Encryption (SME) support"
1527	depends on X86_64 && CPU_SUP_AMD
1528	select DMA_COHERENT_POOL
1529	select ARCH_USE_MEMREMAP_PROT
1530	select INSTRUCTION_DECODER
1531	select ARCH_HAS_CC_PLATFORM
1532	select X86_MEM_ENCRYPT
1533	help
1534	  Say yes to enable support for the encryption of system memory.
1535	  This requires an AMD processor that supports Secure Memory
1536	  Encryption (SME).
1537
1538config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1539	bool "Activate AMD Secure Memory Encryption (SME) by default"
1540	depends on AMD_MEM_ENCRYPT
1541	help
1542	  Say yes to have system memory encrypted by default if running on
1543	  an AMD processor that supports Secure Memory Encryption (SME).
1544
1545	  If set to Y, then the encryption of system memory can be
1546	  deactivated with the mem_encrypt=off command line option.
1547
1548	  If set to N, then the encryption of system memory can be
1549	  activated with the mem_encrypt=on command line option.
1550
1551# Common NUMA Features
1552config NUMA
1553	bool "NUMA Memory Allocation and Scheduler Support"
1554	depends on SMP
1555	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1556	default y if X86_BIGSMP
1557	select USE_PERCPU_NUMA_NODE_ID
1558	help
1559	  Enable NUMA (Non-Uniform Memory Access) support.
1560
1561	  The kernel will try to allocate memory used by a CPU on the
1562	  local memory controller of the CPU and add some more
1563	  NUMA awareness to the kernel.
1564
1565	  For 64-bit this is recommended if the system is Intel Core i7
1566	  (or later), AMD Opteron, or EM64T NUMA.
1567
1568	  For 32-bit this is only needed if you boot a 32-bit
1569	  kernel on a 64-bit NUMA platform.
1570
1571	  Otherwise, you should say N.
1572
1573config AMD_NUMA
1574	def_bool y
1575	prompt "Old style AMD Opteron NUMA detection"
1576	depends on X86_64 && NUMA && PCI
1577	help
1578	  Enable AMD NUMA node topology detection.  You should say Y here if
1579	  you have a multi processor AMD system. This uses an old method to
1580	  read the NUMA configuration directly from the builtin Northbridge
1581	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1582	  which also takes priority if both are compiled in.
1583
1584config X86_64_ACPI_NUMA
1585	def_bool y
1586	prompt "ACPI NUMA detection"
1587	depends on X86_64 && NUMA && ACPI && PCI
1588	select ACPI_NUMA
1589	help
1590	  Enable ACPI SRAT based node topology detection.
1591
1592config NUMA_EMU
1593	bool "NUMA emulation"
1594	depends on NUMA
1595	help
1596	  Enable NUMA emulation. A flat machine will be split
1597	  into virtual nodes when booted with "numa=fake=N", where N is the
1598	  number of nodes. This is only useful for debugging.
1599
1600config NODES_SHIFT
1601	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1602	range 1 10
1603	default "10" if MAXSMP
1604	default "6" if X86_64
1605	default "3"
1606	depends on NUMA
1607	help
1608	  Specify the maximum number of NUMA Nodes available on the target
1609	  system.  Increases memory reserved to accommodate various tables.
1610
1611config ARCH_FLATMEM_ENABLE
1612	def_bool y
1613	depends on X86_32 && !NUMA
1614
1615config ARCH_SPARSEMEM_ENABLE
1616	def_bool y
1617	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1618	select SPARSEMEM_STATIC if X86_32
1619	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1620
1621config ARCH_SPARSEMEM_DEFAULT
1622	def_bool X86_64 || (NUMA && X86_32)
1623
1624config ARCH_SELECT_MEMORY_MODEL
1625	def_bool y
1626	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1627
1628config ARCH_MEMORY_PROBE
1629	bool "Enable sysfs memory/probe interface"
1630	depends on MEMORY_HOTPLUG
1631	help
1632	  This option enables a sysfs memory/probe interface for testing.
1633	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1634	  If you are unsure how to answer this question, answer N.
1635
1636config ARCH_PROC_KCORE_TEXT
1637	def_bool y
1638	depends on X86_64 && PROC_KCORE
1639
1640config ILLEGAL_POINTER_VALUE
1641	hex
1642	default 0 if X86_32
1643	default 0xdead000000000000 if X86_64
1644
1645config X86_PMEM_LEGACY_DEVICE
1646	bool
1647
1648config X86_PMEM_LEGACY
1649	tristate "Support non-standard NVDIMMs and ADR protected memory"
1650	depends on PHYS_ADDR_T_64BIT
1651	depends on BLK_DEV
1652	select X86_PMEM_LEGACY_DEVICE
1653	select NUMA_KEEP_MEMINFO if NUMA
1654	select LIBNVDIMM
1655	help
1656	  Treat memory marked using the non-standard e820 type of 12 as used
1657	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1658	  The kernel will offer these regions to the 'pmem' driver so
1659	  they can be used for persistent storage.
1660
1661	  Say Y if unsure.
1662
1663config HIGHPTE
1664	bool "Allocate 3rd-level pagetables from highmem"
1665	depends on HIGHMEM
1666	help
1667	  The VM uses one page table entry for each page of physical memory.
1668	  For systems with a lot of RAM, this can be wasteful of precious
1669	  low memory.  Setting this option will put user-space page table
1670	  entries in high memory.
1671
1672config X86_CHECK_BIOS_CORRUPTION
1673	bool "Check for low memory corruption"
1674	help
1675	  Periodically check for memory corruption in low memory, which
1676	  is suspected to be caused by BIOS.  Even when enabled in the
1677	  configuration, it is disabled at runtime.  Enable it by
1678	  setting "memory_corruption_check=1" on the kernel command
1679	  line.  By default it scans the low 64k of memory every 60
1680	  seconds; see the memory_corruption_check_size and
1681	  memory_corruption_check_period parameters in
1682	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1683
1684	  When enabled with the default parameters, this option has
1685	  almost no overhead, as it reserves a relatively small amount
1686	  of memory and scans it infrequently.  It both detects corruption
1687	  and prevents it from affecting the running system.
1688
1689	  It is, however, intended as a diagnostic tool; if repeatable
1690	  BIOS-originated corruption always affects the same memory,
1691	  you can use memmap= to prevent the kernel from using that
1692	  memory.
1693
1694config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1695	bool "Set the default setting of memory_corruption_check"
1696	depends on X86_CHECK_BIOS_CORRUPTION
1697	default y
1698	help
1699	  Set whether the default state of memory_corruption_check is
1700	  on or off.
1701
1702config MATH_EMULATION
1703	bool
1704	depends on MODIFY_LDT_SYSCALL
1705	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1706	help
1707	  Linux can emulate a math coprocessor (used for floating point
1708	  operations) if you don't have one. 486DX and Pentium processors have
1709	  a math coprocessor built in, 486SX and 386 do not, unless you added
1710	  a 487DX or 387, respectively. (The messages during boot time can
1711	  give you some hints here ["man dmesg"].) Everyone needs either a
1712	  coprocessor or this emulation.
1713
1714	  If you don't have a math coprocessor, you need to say Y here; if you
1715	  say Y here even though you have a coprocessor, the coprocessor will
1716	  be used nevertheless. (This behavior can be changed with the kernel
1717	  command line option "no387", which comes handy if your coprocessor
1718	  is broken. Try "man bootparam" or see the documentation of your boot
1719	  loader (lilo or loadlin) about how to pass options to the kernel at
1720	  boot time.) This means that it is a good idea to say Y here if you
1721	  intend to use this kernel on different machines.
1722
1723	  More information about the internals of the Linux math coprocessor
1724	  emulation can be found in <file:arch/x86/math-emu/README>.
1725
1726	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1727	  kernel, it won't hurt.
1728
1729config MTRR
1730	def_bool y
1731	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1732	help
1733	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1734	  the Memory Type Range Registers (MTRRs) may be used to control
1735	  processor access to memory ranges. This is most useful if you have
1736	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1737	  allows bus write transfers to be combined into a larger transfer
1738	  before bursting over the PCI/AGP bus. This can increase performance
1739	  of image write operations 2.5 times or more. Saying Y here creates a
1740	  /proc/mtrr file which may be used to manipulate your processor's
1741	  MTRRs. Typically the X server should use this.
1742
1743	  This code has a reasonably generic interface so that similar
1744	  control registers on other processors can be easily supported
1745	  as well:
1746
1747	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1748	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1749	  these, the ARRs are used to emulate the MTRRs.
1750	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1751	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1752	  write-combining. All of these processors are supported by this code
1753	  and it makes sense to say Y here if you have one of them.
1754
1755	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1756	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1757	  can lead to all sorts of problems, so it's good to say Y here.
1758
1759	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1760	  just add about 9 KB to your kernel.
1761
1762	  See <file:Documentation/x86/mtrr.rst> for more information.
1763
1764config MTRR_SANITIZER
1765	def_bool y
1766	prompt "MTRR cleanup support"
1767	depends on MTRR
1768	help
1769	  Convert MTRR layout from continuous to discrete, so X drivers can
1770	  add writeback entries.
1771
1772	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1773	  The largest mtrr entry size for a continuous block can be set with
1774	  mtrr_chunk_size.
1775
1776	  If unsure, say Y.
1777
1778config MTRR_SANITIZER_ENABLE_DEFAULT
1779	int "MTRR cleanup enable value (0-1)"
1780	range 0 1
1781	default "0"
1782	depends on MTRR_SANITIZER
1783	help
1784	  Enable mtrr cleanup default value
1785
1786config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1787	int "MTRR cleanup spare reg num (0-7)"
1788	range 0 7
1789	default "1"
1790	depends on MTRR_SANITIZER
1791	help
1792	  mtrr cleanup spare entries default, it can be changed via
1793	  mtrr_spare_reg_nr=N on the kernel command line.
1794
1795config X86_PAT
1796	def_bool y
1797	prompt "x86 PAT support" if EXPERT
1798	depends on MTRR
1799	help
1800	  Use PAT attributes to setup page level cache control.
1801
1802	  PATs are the modern equivalents of MTRRs and are much more
1803	  flexible than MTRRs.
1804
1805	  Say N here if you see bootup problems (boot crash, boot hang,
1806	  spontaneous reboots) or a non-working video driver.
1807
1808	  If unsure, say Y.
1809
1810config ARCH_USES_PG_UNCACHED
1811	def_bool y
1812	depends on X86_PAT
1813
1814config ARCH_RANDOM
1815	def_bool y
1816	prompt "x86 architectural random number generator" if EXPERT
1817	help
1818	  Enable the x86 architectural RDRAND instruction
1819	  (Intel Bull Mountain technology) to generate random numbers.
1820	  If supported, this is a high bandwidth, cryptographically
1821	  secure hardware random number generator.
1822
1823config X86_UMIP
1824	def_bool y
1825	prompt "User Mode Instruction Prevention" if EXPERT
1826	help
1827	  User Mode Instruction Prevention (UMIP) is a security feature in
1828	  some x86 processors. If enabled, a general protection fault is
1829	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1830	  executed in user mode. These instructions unnecessarily expose
1831	  information about the hardware state.
1832
1833	  The vast majority of applications do not use these instructions.
1834	  For the very few that do, software emulation is provided in
1835	  specific cases in protected and virtual-8086 modes. Emulated
1836	  results are dummy.
1837
1838config CC_HAS_IBT
1839	# GCC >= 9 and binutils >= 2.29
1840	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1841	# Clang/LLVM >= 14
1842	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1843	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1844	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1845		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1846		  $(as-instr,endbr64)
1847
1848config X86_KERNEL_IBT
1849	prompt "Indirect Branch Tracking"
1850	bool
1851	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1852	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1853	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1854	select OBJTOOL
1855	help
1856	  Build the kernel with support for Indirect Branch Tracking, a
1857	  hardware support course-grain forward-edge Control Flow Integrity
1858	  protection. It enforces that all indirect calls must land on
1859	  an ENDBR instruction, as such, the compiler will instrument the
1860	  code with them to make this happen.
1861
1862	  In addition to building the kernel with IBT, seal all functions that
1863	  are not indirect call targets, avoiding them ever becoming one.
1864
1865	  This requires LTO like objtool runs and will slow down the build. It
1866	  does significantly reduce the number of ENDBR instructions in the
1867	  kernel image.
1868
1869config X86_INTEL_MEMORY_PROTECTION_KEYS
1870	prompt "Memory Protection Keys"
1871	def_bool y
1872	# Note: only available in 64-bit mode
1873	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1874	select ARCH_USES_HIGH_VMA_FLAGS
1875	select ARCH_HAS_PKEYS
1876	help
1877	  Memory Protection Keys provides a mechanism for enforcing
1878	  page-based protections, but without requiring modification of the
1879	  page tables when an application changes protection domains.
1880
1881	  For details, see Documentation/core-api/protection-keys.rst
1882
1883	  If unsure, say y.
1884
1885choice
1886	prompt "TSX enable mode"
1887	depends on CPU_SUP_INTEL
1888	default X86_INTEL_TSX_MODE_OFF
1889	help
1890	  Intel's TSX (Transactional Synchronization Extensions) feature
1891	  allows to optimize locking protocols through lock elision which
1892	  can lead to a noticeable performance boost.
1893
1894	  On the other hand it has been shown that TSX can be exploited
1895	  to form side channel attacks (e.g. TAA) and chances are there
1896	  will be more of those attacks discovered in the future.
1897
1898	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1899	  might override this decision by tsx=on the command line parameter.
1900	  Even with TSX enabled, the kernel will attempt to enable the best
1901	  possible TAA mitigation setting depending on the microcode available
1902	  for the particular machine.
1903
1904	  This option allows to set the default tsx mode between tsx=on, =off
1905	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1906	  details.
1907
1908	  Say off if not sure, auto if TSX is in use but it should be used on safe
1909	  platforms or on if TSX is in use and the security aspect of tsx is not
1910	  relevant.
1911
1912config X86_INTEL_TSX_MODE_OFF
1913	bool "off"
1914	help
1915	  TSX is disabled if possible - equals to tsx=off command line parameter.
1916
1917config X86_INTEL_TSX_MODE_ON
1918	bool "on"
1919	help
1920	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1921	  line parameter.
1922
1923config X86_INTEL_TSX_MODE_AUTO
1924	bool "auto"
1925	help
1926	  TSX is enabled on TSX capable HW that is believed to be safe against
1927	  side channel attacks- equals the tsx=auto command line parameter.
1928endchoice
1929
1930config X86_SGX
1931	bool "Software Guard eXtensions (SGX)"
1932	depends on X86_64 && CPU_SUP_INTEL
1933	depends on CRYPTO=y
1934	depends on CRYPTO_SHA256=y
1935	select SRCU
1936	select MMU_NOTIFIER
1937	select NUMA_KEEP_MEMINFO if NUMA
1938	select XARRAY_MULTI
1939	help
1940	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1941	  that can be used by applications to set aside private regions of code
1942	  and data, referred to as enclaves. An enclave's private memory can
1943	  only be accessed by code running within the enclave. Accesses from
1944	  outside the enclave, including other enclaves, are disallowed by
1945	  hardware.
1946
1947	  If unsure, say N.
1948
1949config EFI
1950	bool "EFI runtime service support"
1951	depends on ACPI
1952	select UCS2_STRING
1953	select EFI_RUNTIME_WRAPPERS
1954	select ARCH_USE_MEMREMAP_PROT
1955	help
1956	  This enables the kernel to use EFI runtime services that are
1957	  available (such as the EFI variable services).
1958
1959	  This option is only useful on systems that have EFI firmware.
1960	  In addition, you should use the latest ELILO loader available
1961	  at <http://elilo.sourceforge.net> in order to take advantage
1962	  of EFI runtime services. However, even with this option, the
1963	  resultant kernel should continue to boot on existing non-EFI
1964	  platforms.
1965
1966config EFI_STUB
1967	bool "EFI stub support"
1968	depends on EFI
1969	depends on $(cc-option,-mabi=ms) || X86_32
1970	select RELOCATABLE
1971	help
1972	  This kernel feature allows a bzImage to be loaded directly
1973	  by EFI firmware without the use of a bootloader.
1974
1975	  See Documentation/admin-guide/efi-stub.rst for more information.
1976
1977config EFI_MIXED
1978	bool "EFI mixed-mode support"
1979	depends on EFI_STUB && X86_64
1980	help
1981	  Enabling this feature allows a 64-bit kernel to be booted
1982	  on a 32-bit firmware, provided that your CPU supports 64-bit
1983	  mode.
1984
1985	  Note that it is not possible to boot a mixed-mode enabled
1986	  kernel via the EFI boot stub - a bootloader that supports
1987	  the EFI handover protocol must be used.
1988
1989	  If unsure, say N.
1990
1991source "kernel/Kconfig.hz"
1992
1993config KEXEC
1994	bool "kexec system call"
1995	select KEXEC_CORE
1996	help
1997	  kexec is a system call that implements the ability to shutdown your
1998	  current kernel, and to start another kernel.  It is like a reboot
1999	  but it is independent of the system firmware.   And like a reboot
2000	  you can start any kernel with it, not just Linux.
2001
2002	  The name comes from the similarity to the exec system call.
2003
2004	  It is an ongoing process to be certain the hardware in a machine
2005	  is properly shutdown, so do not be surprised if this code does not
2006	  initially work for you.  As of this writing the exact hardware
2007	  interface is strongly in flux, so no good recommendation can be
2008	  made.
2009
2010config KEXEC_FILE
2011	bool "kexec file based system call"
2012	select KEXEC_CORE
2013	select BUILD_BIN2C
2014	depends on X86_64
2015	depends on CRYPTO=y
2016	depends on CRYPTO_SHA256=y
2017	help
2018	  This is new version of kexec system call. This system call is
2019	  file based and takes file descriptors as system call argument
2020	  for kernel and initramfs as opposed to list of segments as
2021	  accepted by previous system call.
2022
2023config ARCH_HAS_KEXEC_PURGATORY
2024	def_bool KEXEC_FILE
2025
2026config KEXEC_SIG
2027	bool "Verify kernel signature during kexec_file_load() syscall"
2028	depends on KEXEC_FILE
2029	help
2030
2031	  This option makes the kexec_file_load() syscall check for a valid
2032	  signature of the kernel image.  The image can still be loaded without
2033	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2034	  there's a signature that we can check, then it must be valid.
2035
2036	  In addition to this option, you need to enable signature
2037	  verification for the corresponding kernel image type being
2038	  loaded in order for this to work.
2039
2040config KEXEC_SIG_FORCE
2041	bool "Require a valid signature in kexec_file_load() syscall"
2042	depends on KEXEC_SIG
2043	help
2044	  This option makes kernel signature verification mandatory for
2045	  the kexec_file_load() syscall.
2046
2047config KEXEC_BZIMAGE_VERIFY_SIG
2048	bool "Enable bzImage signature verification support"
2049	depends on KEXEC_SIG
2050	depends on SIGNED_PE_FILE_VERIFICATION
2051	select SYSTEM_TRUSTED_KEYRING
2052	help
2053	  Enable bzImage signature verification support.
2054
2055config CRASH_DUMP
2056	bool "kernel crash dumps"
2057	depends on X86_64 || (X86_32 && HIGHMEM)
2058	help
2059	  Generate crash dump after being started by kexec.
2060	  This should be normally only set in special crash dump kernels
2061	  which are loaded in the main kernel with kexec-tools into
2062	  a specially reserved region and then later executed after
2063	  a crash by kdump/kexec. The crash dump kernel must be compiled
2064	  to a memory address not used by the main kernel or BIOS using
2065	  PHYSICAL_START, or it must be built as a relocatable image
2066	  (CONFIG_RELOCATABLE=y).
2067	  For more details see Documentation/admin-guide/kdump/kdump.rst
2068
2069config KEXEC_JUMP
2070	bool "kexec jump"
2071	depends on KEXEC && HIBERNATION
2072	help
2073	  Jump between original kernel and kexeced kernel and invoke
2074	  code in physical address mode via KEXEC
2075
2076config PHYSICAL_START
2077	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2078	default "0x1000000"
2079	help
2080	  This gives the physical address where the kernel is loaded.
2081
2082	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2083	  bzImage will decompress itself to above physical address and
2084	  run from there. Otherwise, bzImage will run from the address where
2085	  it has been loaded by the boot loader and will ignore above physical
2086	  address.
2087
2088	  In normal kdump cases one does not have to set/change this option
2089	  as now bzImage can be compiled as a completely relocatable image
2090	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2091	  address. This option is mainly useful for the folks who don't want
2092	  to use a bzImage for capturing the crash dump and want to use a
2093	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2094	  to be specifically compiled to run from a specific memory area
2095	  (normally a reserved region) and this option comes handy.
2096
2097	  So if you are using bzImage for capturing the crash dump,
2098	  leave the value here unchanged to 0x1000000 and set
2099	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2100	  for capturing the crash dump change this value to start of
2101	  the reserved region.  In other words, it can be set based on
2102	  the "X" value as specified in the "crashkernel=YM@XM"
2103	  command line boot parameter passed to the panic-ed
2104	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2105	  for more details about crash dumps.
2106
2107	  Usage of bzImage for capturing the crash dump is recommended as
2108	  one does not have to build two kernels. Same kernel can be used
2109	  as production kernel and capture kernel. Above option should have
2110	  gone away after relocatable bzImage support is introduced. But it
2111	  is present because there are users out there who continue to use
2112	  vmlinux for dump capture. This option should go away down the
2113	  line.
2114
2115	  Don't change this unless you know what you are doing.
2116
2117config RELOCATABLE
2118	bool "Build a relocatable kernel"
2119	default y
2120	help
2121	  This builds a kernel image that retains relocation information
2122	  so it can be loaded someplace besides the default 1MB.
2123	  The relocations tend to make the kernel binary about 10% larger,
2124	  but are discarded at runtime.
2125
2126	  One use is for the kexec on panic case where the recovery kernel
2127	  must live at a different physical address than the primary
2128	  kernel.
2129
2130	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2131	  it has been loaded at and the compile time physical address
2132	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2133
2134config RANDOMIZE_BASE
2135	bool "Randomize the address of the kernel image (KASLR)"
2136	depends on RELOCATABLE
2137	default y
2138	help
2139	  In support of Kernel Address Space Layout Randomization (KASLR),
2140	  this randomizes the physical address at which the kernel image
2141	  is decompressed and the virtual address where the kernel
2142	  image is mapped, as a security feature that deters exploit
2143	  attempts relying on knowledge of the location of kernel
2144	  code internals.
2145
2146	  On 64-bit, the kernel physical and virtual addresses are
2147	  randomized separately. The physical address will be anywhere
2148	  between 16MB and the top of physical memory (up to 64TB). The
2149	  virtual address will be randomized from 16MB up to 1GB (9 bits
2150	  of entropy). Note that this also reduces the memory space
2151	  available to kernel modules from 1.5GB to 1GB.
2152
2153	  On 32-bit, the kernel physical and virtual addresses are
2154	  randomized together. They will be randomized from 16MB up to
2155	  512MB (8 bits of entropy).
2156
2157	  Entropy is generated using the RDRAND instruction if it is
2158	  supported. If RDTSC is supported, its value is mixed into
2159	  the entropy pool as well. If neither RDRAND nor RDTSC are
2160	  supported, then entropy is read from the i8254 timer. The
2161	  usable entropy is limited by the kernel being built using
2162	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2163	  minimum of 2MB. As a result, only 10 bits of entropy are
2164	  theoretically possible, but the implementations are further
2165	  limited due to memory layouts.
2166
2167	  If unsure, say Y.
2168
2169# Relocation on x86 needs some additional build support
2170config X86_NEED_RELOCS
2171	def_bool y
2172	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2173
2174config PHYSICAL_ALIGN
2175	hex "Alignment value to which kernel should be aligned"
2176	default "0x200000"
2177	range 0x2000 0x1000000 if X86_32
2178	range 0x200000 0x1000000 if X86_64
2179	help
2180	  This value puts the alignment restrictions on physical address
2181	  where kernel is loaded and run from. Kernel is compiled for an
2182	  address which meets above alignment restriction.
2183
2184	  If bootloader loads the kernel at a non-aligned address and
2185	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2186	  address aligned to above value and run from there.
2187
2188	  If bootloader loads the kernel at a non-aligned address and
2189	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2190	  load address and decompress itself to the address it has been
2191	  compiled for and run from there. The address for which kernel is
2192	  compiled already meets above alignment restrictions. Hence the
2193	  end result is that kernel runs from a physical address meeting
2194	  above alignment restrictions.
2195
2196	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2197	  this value must be a multiple of 0x200000.
2198
2199	  Don't change this unless you know what you are doing.
2200
2201config DYNAMIC_MEMORY_LAYOUT
2202	bool
2203	help
2204	  This option makes base addresses of vmalloc and vmemmap as well as
2205	  __PAGE_OFFSET movable during boot.
2206
2207config RANDOMIZE_MEMORY
2208	bool "Randomize the kernel memory sections"
2209	depends on X86_64
2210	depends on RANDOMIZE_BASE
2211	select DYNAMIC_MEMORY_LAYOUT
2212	default RANDOMIZE_BASE
2213	help
2214	  Randomizes the base virtual address of kernel memory sections
2215	  (physical memory mapping, vmalloc & vmemmap). This security feature
2216	  makes exploits relying on predictable memory locations less reliable.
2217
2218	  The order of allocations remains unchanged. Entropy is generated in
2219	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2220	  configuration have in average 30,000 different possible virtual
2221	  addresses for each memory section.
2222
2223	  If unsure, say Y.
2224
2225config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2226	hex "Physical memory mapping padding" if EXPERT
2227	depends on RANDOMIZE_MEMORY
2228	default "0xa" if MEMORY_HOTPLUG
2229	default "0x0"
2230	range 0x1 0x40 if MEMORY_HOTPLUG
2231	range 0x0 0x40
2232	help
2233	  Define the padding in terabytes added to the existing physical
2234	  memory size during kernel memory randomization. It is useful
2235	  for memory hotplug support but reduces the entropy available for
2236	  address randomization.
2237
2238	  If unsure, leave at the default value.
2239
2240config HOTPLUG_CPU
2241	def_bool y
2242	depends on SMP
2243
2244config BOOTPARAM_HOTPLUG_CPU0
2245	bool "Set default setting of cpu0_hotpluggable"
2246	depends on HOTPLUG_CPU
2247	help
2248	  Set whether default state of cpu0_hotpluggable is on or off.
2249
2250	  Say Y here to enable CPU0 hotplug by default. If this switch
2251	  is turned on, there is no need to give cpu0_hotplug kernel
2252	  parameter and the CPU0 hotplug feature is enabled by default.
2253
2254	  Please note: there are two known CPU0 dependencies if you want
2255	  to enable the CPU0 hotplug feature either by this switch or by
2256	  cpu0_hotplug kernel parameter.
2257
2258	  First, resume from hibernate or suspend always starts from CPU0.
2259	  So hibernate and suspend are prevented if CPU0 is offline.
2260
2261	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2262	  offline if any interrupt can not migrate out of CPU0. There may
2263	  be other CPU0 dependencies.
2264
2265	  Please make sure the dependencies are under your control before
2266	  you enable this feature.
2267
2268	  Say N if you don't want to enable CPU0 hotplug feature by default.
2269	  You still can enable the CPU0 hotplug feature at boot by kernel
2270	  parameter cpu0_hotplug.
2271
2272config DEBUG_HOTPLUG_CPU0
2273	def_bool n
2274	prompt "Debug CPU0 hotplug"
2275	depends on HOTPLUG_CPU
2276	help
2277	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2278	  soon as possible and boots up userspace with CPU0 offlined. User
2279	  can online CPU0 back after boot time.
2280
2281	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2282	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2283	  compilation or giving cpu0_hotplug kernel parameter at boot.
2284
2285	  If unsure, say N.
2286
2287config COMPAT_VDSO
2288	def_bool n
2289	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2290	depends on COMPAT_32
2291	help
2292	  Certain buggy versions of glibc will crash if they are
2293	  presented with a 32-bit vDSO that is not mapped at the address
2294	  indicated in its segment table.
2295
2296	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2297	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2298	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2299	  the only released version with the bug, but OpenSUSE 9
2300	  contains a buggy "glibc 2.3.2".
2301
2302	  The symptom of the bug is that everything crashes on startup, saying:
2303	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2304
2305	  Saying Y here changes the default value of the vdso32 boot
2306	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2307	  This works around the glibc bug but hurts performance.
2308
2309	  If unsure, say N: if you are compiling your own kernel, you
2310	  are unlikely to be using a buggy version of glibc.
2311
2312choice
2313	prompt "vsyscall table for legacy applications"
2314	depends on X86_64
2315	default LEGACY_VSYSCALL_XONLY
2316	help
2317	  Legacy user code that does not know how to find the vDSO expects
2318	  to be able to issue three syscalls by calling fixed addresses in
2319	  kernel space. Since this location is not randomized with ASLR,
2320	  it can be used to assist security vulnerability exploitation.
2321
2322	  This setting can be changed at boot time via the kernel command
2323	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2324	  is deprecated and can only be enabled using the kernel command
2325	  line.
2326
2327	  On a system with recent enough glibc (2.14 or newer) and no
2328	  static binaries, you can say None without a performance penalty
2329	  to improve security.
2330
2331	  If unsure, select "Emulate execution only".
2332
2333	config LEGACY_VSYSCALL_XONLY
2334		bool "Emulate execution only"
2335		help
2336		  The kernel traps and emulates calls into the fixed vsyscall
2337		  address mapping and does not allow reads.  This
2338		  configuration is recommended when userspace might use the
2339		  legacy vsyscall area but support for legacy binary
2340		  instrumentation of legacy code is not needed.  It mitigates
2341		  certain uses of the vsyscall area as an ASLR-bypassing
2342		  buffer.
2343
2344	config LEGACY_VSYSCALL_NONE
2345		bool "None"
2346		help
2347		  There will be no vsyscall mapping at all. This will
2348		  eliminate any risk of ASLR bypass due to the vsyscall
2349		  fixed address mapping. Attempts to use the vsyscalls
2350		  will be reported to dmesg, so that either old or
2351		  malicious userspace programs can be identified.
2352
2353endchoice
2354
2355config CMDLINE_BOOL
2356	bool "Built-in kernel command line"
2357	help
2358	  Allow for specifying boot arguments to the kernel at
2359	  build time.  On some systems (e.g. embedded ones), it is
2360	  necessary or convenient to provide some or all of the
2361	  kernel boot arguments with the kernel itself (that is,
2362	  to not rely on the boot loader to provide them.)
2363
2364	  To compile command line arguments into the kernel,
2365	  set this option to 'Y', then fill in the
2366	  boot arguments in CONFIG_CMDLINE.
2367
2368	  Systems with fully functional boot loaders (i.e. non-embedded)
2369	  should leave this option set to 'N'.
2370
2371config CMDLINE
2372	string "Built-in kernel command string"
2373	depends on CMDLINE_BOOL
2374	default ""
2375	help
2376	  Enter arguments here that should be compiled into the kernel
2377	  image and used at boot time.  If the boot loader provides a
2378	  command line at boot time, it is appended to this string to
2379	  form the full kernel command line, when the system boots.
2380
2381	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2382	  change this behavior.
2383
2384	  In most cases, the command line (whether built-in or provided
2385	  by the boot loader) should specify the device for the root
2386	  file system.
2387
2388config CMDLINE_OVERRIDE
2389	bool "Built-in command line overrides boot loader arguments"
2390	depends on CMDLINE_BOOL && CMDLINE != ""
2391	help
2392	  Set this option to 'Y' to have the kernel ignore the boot loader
2393	  command line, and use ONLY the built-in command line.
2394
2395	  This is used to work around broken boot loaders.  This should
2396	  be set to 'N' under normal conditions.
2397
2398config MODIFY_LDT_SYSCALL
2399	bool "Enable the LDT (local descriptor table)" if EXPERT
2400	default y
2401	help
2402	  Linux can allow user programs to install a per-process x86
2403	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2404	  call.  This is required to run 16-bit or segmented code such as
2405	  DOSEMU or some Wine programs.  It is also used by some very old
2406	  threading libraries.
2407
2408	  Enabling this feature adds a small amount of overhead to
2409	  context switches and increases the low-level kernel attack
2410	  surface.  Disabling it removes the modify_ldt(2) system call.
2411
2412	  Saying 'N' here may make sense for embedded or server kernels.
2413
2414config STRICT_SIGALTSTACK_SIZE
2415	bool "Enforce strict size checking for sigaltstack"
2416	depends on DYNAMIC_SIGFRAME
2417	help
2418	  For historical reasons MINSIGSTKSZ is a constant which became
2419	  already too small with AVX512 support. Add a mechanism to
2420	  enforce strict checking of the sigaltstack size against the
2421	  real size of the FPU frame. This option enables the check
2422	  by default. It can also be controlled via the kernel command
2423	  line option 'strict_sas_size' independent of this config
2424	  switch. Enabling it might break existing applications which
2425	  allocate a too small sigaltstack but 'work' because they
2426	  never get a signal delivered.
2427
2428	  Say 'N' unless you want to really enforce this check.
2429
2430source "kernel/livepatch/Kconfig"
2431
2432endmenu
2433
2434config CC_HAS_SLS
2435	def_bool $(cc-option,-mharden-sls=all)
2436
2437config CC_HAS_RETURN_THUNK
2438	def_bool $(cc-option,-mfunction-return=thunk-extern)
2439
2440menuconfig SPECULATION_MITIGATIONS
2441	bool "Mitigations for speculative execution vulnerabilities"
2442	default y
2443	help
2444	  Say Y here to enable options which enable mitigations for
2445	  speculative execution hardware vulnerabilities.
2446
2447	  If you say N, all mitigations will be disabled. You really
2448	  should know what you are doing to say so.
2449
2450if SPECULATION_MITIGATIONS
2451
2452config PAGE_TABLE_ISOLATION
2453	bool "Remove the kernel mapping in user mode"
2454	default y
2455	depends on (X86_64 || X86_PAE)
2456	help
2457	  This feature reduces the number of hardware side channels by
2458	  ensuring that the majority of kernel addresses are not mapped
2459	  into userspace.
2460
2461	  See Documentation/x86/pti.rst for more details.
2462
2463config RETPOLINE
2464	bool "Avoid speculative indirect branches in kernel"
2465	select OBJTOOL if HAVE_OBJTOOL
2466	default y
2467	help
2468	  Compile kernel with the retpoline compiler options to guard against
2469	  kernel-to-user data leaks by avoiding speculative indirect
2470	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2471	  support for full protection. The kernel may run slower.
2472
2473config RETHUNK
2474	bool "Enable return-thunks"
2475	depends on RETPOLINE && CC_HAS_RETURN_THUNK
2476	select OBJTOOL if HAVE_OBJTOOL
2477	default y if X86_64
2478	help
2479	  Compile the kernel with the return-thunks compiler option to guard
2480	  against kernel-to-user data leaks by avoiding return speculation.
2481	  Requires a compiler with -mfunction-return=thunk-extern
2482	  support for full protection. The kernel may run slower.
2483
2484config CPU_UNRET_ENTRY
2485	bool "Enable UNRET on kernel entry"
2486	depends on CPU_SUP_AMD && RETHUNK && X86_64
2487	default y
2488	help
2489	  Compile the kernel with support for the retbleed=unret mitigation.
2490
2491config CPU_IBPB_ENTRY
2492	bool "Enable IBPB on kernel entry"
2493	depends on CPU_SUP_AMD && X86_64
2494	default y
2495	help
2496	  Compile the kernel with support for the retbleed=ibpb mitigation.
2497
2498config CPU_IBRS_ENTRY
2499	bool "Enable IBRS on kernel entry"
2500	depends on CPU_SUP_INTEL && X86_64
2501	default y
2502	help
2503	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2504	  This mitigates both spectre_v2 and retbleed at great cost to
2505	  performance.
2506
2507config SLS
2508	bool "Mitigate Straight-Line-Speculation"
2509	depends on CC_HAS_SLS && X86_64
2510	select OBJTOOL if HAVE_OBJTOOL
2511	default n
2512	help
2513	  Compile the kernel with straight-line-speculation options to guard
2514	  against straight line speculation. The kernel image might be slightly
2515	  larger.
2516
2517endif
2518
2519config ARCH_HAS_ADD_PAGES
2520	def_bool y
2521	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2522
2523config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2524	def_bool y
2525
2526menu "Power management and ACPI options"
2527
2528config ARCH_HIBERNATION_HEADER
2529	def_bool y
2530	depends on HIBERNATION
2531
2532source "kernel/power/Kconfig"
2533
2534source "drivers/acpi/Kconfig"
2535
2536config X86_APM_BOOT
2537	def_bool y
2538	depends on APM
2539
2540menuconfig APM
2541	tristate "APM (Advanced Power Management) BIOS support"
2542	depends on X86_32 && PM_SLEEP
2543	help
2544	  APM is a BIOS specification for saving power using several different
2545	  techniques. This is mostly useful for battery powered laptops with
2546	  APM compliant BIOSes. If you say Y here, the system time will be
2547	  reset after a RESUME operation, the /proc/apm device will provide
2548	  battery status information, and user-space programs will receive
2549	  notification of APM "events" (e.g. battery status change).
2550
2551	  If you select "Y" here, you can disable actual use of the APM
2552	  BIOS by passing the "apm=off" option to the kernel at boot time.
2553
2554	  Note that the APM support is almost completely disabled for
2555	  machines with more than one CPU.
2556
2557	  In order to use APM, you will need supporting software. For location
2558	  and more information, read <file:Documentation/power/apm-acpi.rst>
2559	  and the Battery Powered Linux mini-HOWTO, available from
2560	  <http://www.tldp.org/docs.html#howto>.
2561
2562	  This driver does not spin down disk drives (see the hdparm(8)
2563	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2564	  VESA-compliant "green" monitors.
2565
2566	  This driver does not support the TI 4000M TravelMate and the ACER
2567	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2568	  desktop machines also don't have compliant BIOSes, and this driver
2569	  may cause those machines to panic during the boot phase.
2570
2571	  Generally, if you don't have a battery in your machine, there isn't
2572	  much point in using this driver and you should say N. If you get
2573	  random kernel OOPSes or reboots that don't seem to be related to
2574	  anything, try disabling/enabling this option (or disabling/enabling
2575	  APM in your BIOS).
2576
2577	  Some other things you should try when experiencing seemingly random,
2578	  "weird" problems:
2579
2580	  1) make sure that you have enough swap space and that it is
2581	  enabled.
2582	  2) pass the "no-hlt" option to the kernel
2583	  3) switch on floating point emulation in the kernel and pass
2584	  the "no387" option to the kernel
2585	  4) pass the "floppy=nodma" option to the kernel
2586	  5) pass the "mem=4M" option to the kernel (thereby disabling
2587	  all but the first 4 MB of RAM)
2588	  6) make sure that the CPU is not over clocked.
2589	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2590	  8) disable the cache from your BIOS settings
2591	  9) install a fan for the video card or exchange video RAM
2592	  10) install a better fan for the CPU
2593	  11) exchange RAM chips
2594	  12) exchange the motherboard.
2595
2596	  To compile this driver as a module, choose M here: the
2597	  module will be called apm.
2598
2599if APM
2600
2601config APM_IGNORE_USER_SUSPEND
2602	bool "Ignore USER SUSPEND"
2603	help
2604	  This option will ignore USER SUSPEND requests. On machines with a
2605	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2606	  series notebooks, it is necessary to say Y because of a BIOS bug.
2607
2608config APM_DO_ENABLE
2609	bool "Enable PM at boot time"
2610	help
2611	  Enable APM features at boot time. From page 36 of the APM BIOS
2612	  specification: "When disabled, the APM BIOS does not automatically
2613	  power manage devices, enter the Standby State, enter the Suspend
2614	  State, or take power saving steps in response to CPU Idle calls."
2615	  This driver will make CPU Idle calls when Linux is idle (unless this
2616	  feature is turned off -- see "Do CPU IDLE calls", below). This
2617	  should always save battery power, but more complicated APM features
2618	  will be dependent on your BIOS implementation. You may need to turn
2619	  this option off if your computer hangs at boot time when using APM
2620	  support, or if it beeps continuously instead of suspending. Turn
2621	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2622	  T400CDT. This is off by default since most machines do fine without
2623	  this feature.
2624
2625config APM_CPU_IDLE
2626	depends on CPU_IDLE
2627	bool "Make CPU Idle calls when idle"
2628	help
2629	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2630	  On some machines, this can activate improved power savings, such as
2631	  a slowed CPU clock rate, when the machine is idle. These idle calls
2632	  are made after the idle loop has run for some length of time (e.g.,
2633	  333 mS). On some machines, this will cause a hang at boot time or
2634	  whenever the CPU becomes idle. (On machines with more than one CPU,
2635	  this option does nothing.)
2636
2637config APM_DISPLAY_BLANK
2638	bool "Enable console blanking using APM"
2639	help
2640	  Enable console blanking using the APM. Some laptops can use this to
2641	  turn off the LCD backlight when the screen blanker of the Linux
2642	  virtual console blanks the screen. Note that this is only used by
2643	  the virtual console screen blanker, and won't turn off the backlight
2644	  when using the X Window system. This also doesn't have anything to
2645	  do with your VESA-compliant power-saving monitor. Further, this
2646	  option doesn't work for all laptops -- it might not turn off your
2647	  backlight at all, or it might print a lot of errors to the console,
2648	  especially if you are using gpm.
2649
2650config APM_ALLOW_INTS
2651	bool "Allow interrupts during APM BIOS calls"
2652	help
2653	  Normally we disable external interrupts while we are making calls to
2654	  the APM BIOS as a measure to lessen the effects of a badly behaving
2655	  BIOS implementation.  The BIOS should reenable interrupts if it
2656	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2657	  many of the newer IBM Thinkpads.  If you experience hangs when you
2658	  suspend, try setting this to Y.  Otherwise, say N.
2659
2660endif # APM
2661
2662source "drivers/cpufreq/Kconfig"
2663
2664source "drivers/cpuidle/Kconfig"
2665
2666source "drivers/idle/Kconfig"
2667
2668endmenu
2669
2670menu "Bus options (PCI etc.)"
2671
2672choice
2673	prompt "PCI access mode"
2674	depends on X86_32 && PCI
2675	default PCI_GOANY
2676	help
2677	  On PCI systems, the BIOS can be used to detect the PCI devices and
2678	  determine their configuration. However, some old PCI motherboards
2679	  have BIOS bugs and may crash if this is done. Also, some embedded
2680	  PCI-based systems don't have any BIOS at all. Linux can also try to
2681	  detect the PCI hardware directly without using the BIOS.
2682
2683	  With this option, you can specify how Linux should detect the
2684	  PCI devices. If you choose "BIOS", the BIOS will be used,
2685	  if you choose "Direct", the BIOS won't be used, and if you
2686	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2687	  If you choose "Any", the kernel will try MMCONFIG, then the
2688	  direct access method and falls back to the BIOS if that doesn't
2689	  work. If unsure, go with the default, which is "Any".
2690
2691config PCI_GOBIOS
2692	bool "BIOS"
2693
2694config PCI_GOMMCONFIG
2695	bool "MMConfig"
2696
2697config PCI_GODIRECT
2698	bool "Direct"
2699
2700config PCI_GOOLPC
2701	bool "OLPC XO-1"
2702	depends on OLPC
2703
2704config PCI_GOANY
2705	bool "Any"
2706
2707endchoice
2708
2709config PCI_BIOS
2710	def_bool y
2711	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2712
2713# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2714config PCI_DIRECT
2715	def_bool y
2716	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2717
2718config PCI_MMCONFIG
2719	bool "Support mmconfig PCI config space access" if X86_64
2720	default y
2721	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2722	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2723
2724config PCI_OLPC
2725	def_bool y
2726	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2727
2728config PCI_XEN
2729	def_bool y
2730	depends on PCI && XEN
2731
2732config MMCONF_FAM10H
2733	def_bool y
2734	depends on X86_64 && PCI_MMCONFIG && ACPI
2735
2736config PCI_CNB20LE_QUIRK
2737	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2738	depends on PCI
2739	help
2740	  Read the PCI windows out of the CNB20LE host bridge. This allows
2741	  PCI hotplug to work on systems with the CNB20LE chipset which do
2742	  not have ACPI.
2743
2744	  There's no public spec for this chipset, and this functionality
2745	  is known to be incomplete.
2746
2747	  You should say N unless you know you need this.
2748
2749config ISA_BUS
2750	bool "ISA bus support on modern systems" if EXPERT
2751	help
2752	  Expose ISA bus device drivers and options available for selection and
2753	  configuration. Enable this option if your target machine has an ISA
2754	  bus. ISA is an older system, displaced by PCI and newer bus
2755	  architectures -- if your target machine is modern, it probably does
2756	  not have an ISA bus.
2757
2758	  If unsure, say N.
2759
2760# x86_64 have no ISA slots, but can have ISA-style DMA.
2761config ISA_DMA_API
2762	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2763	default y
2764	help
2765	  Enables ISA-style DMA support for devices requiring such controllers.
2766	  If unsure, say Y.
2767
2768if X86_32
2769
2770config ISA
2771	bool "ISA support"
2772	help
2773	  Find out whether you have ISA slots on your motherboard.  ISA is the
2774	  name of a bus system, i.e. the way the CPU talks to the other stuff
2775	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2776	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2777	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2778
2779config SCx200
2780	tristate "NatSemi SCx200 support"
2781	help
2782	  This provides basic support for National Semiconductor's
2783	  (now AMD's) Geode processors.  The driver probes for the
2784	  PCI-IDs of several on-chip devices, so its a good dependency
2785	  for other scx200_* drivers.
2786
2787	  If compiled as a module, the driver is named scx200.
2788
2789config SCx200HR_TIMER
2790	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2791	depends on SCx200
2792	default y
2793	help
2794	  This driver provides a clocksource built upon the on-chip
2795	  27MHz high-resolution timer.  Its also a workaround for
2796	  NSC Geode SC-1100's buggy TSC, which loses time when the
2797	  processor goes idle (as is done by the scheduler).  The
2798	  other workaround is idle=poll boot option.
2799
2800config OLPC
2801	bool "One Laptop Per Child support"
2802	depends on !X86_PAE
2803	select GPIOLIB
2804	select OF
2805	select OF_PROMTREE
2806	select IRQ_DOMAIN
2807	select OLPC_EC
2808	help
2809	  Add support for detecting the unique features of the OLPC
2810	  XO hardware.
2811
2812config OLPC_XO1_PM
2813	bool "OLPC XO-1 Power Management"
2814	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2815	help
2816	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2817
2818config OLPC_XO1_RTC
2819	bool "OLPC XO-1 Real Time Clock"
2820	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2821	help
2822	  Add support for the XO-1 real time clock, which can be used as a
2823	  programmable wakeup source.
2824
2825config OLPC_XO1_SCI
2826	bool "OLPC XO-1 SCI extras"
2827	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2828	depends on INPUT=y
2829	select POWER_SUPPLY
2830	help
2831	  Add support for SCI-based features of the OLPC XO-1 laptop:
2832	   - EC-driven system wakeups
2833	   - Power button
2834	   - Ebook switch
2835	   - Lid switch
2836	   - AC adapter status updates
2837	   - Battery status updates
2838
2839config OLPC_XO15_SCI
2840	bool "OLPC XO-1.5 SCI extras"
2841	depends on OLPC && ACPI
2842	select POWER_SUPPLY
2843	help
2844	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2845	   - EC-driven system wakeups
2846	   - AC adapter status updates
2847	   - Battery status updates
2848
2849config ALIX
2850	bool "PCEngines ALIX System Support (LED setup)"
2851	select GPIOLIB
2852	help
2853	  This option enables system support for the PCEngines ALIX.
2854	  At present this just sets up LEDs for GPIO control on
2855	  ALIX2/3/6 boards.  However, other system specific setup should
2856	  get added here.
2857
2858	  Note: You must still enable the drivers for GPIO and LED support
2859	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2860
2861	  Note: You have to set alix.force=1 for boards with Award BIOS.
2862
2863config NET5501
2864	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2865	select GPIOLIB
2866	help
2867	  This option enables system support for the Soekris Engineering net5501.
2868
2869config GEOS
2870	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2871	select GPIOLIB
2872	depends on DMI
2873	help
2874	  This option enables system support for the Traverse Technologies GEOS.
2875
2876config TS5500
2877	bool "Technologic Systems TS-5500 platform support"
2878	depends on MELAN
2879	select CHECK_SIGNATURE
2880	select NEW_LEDS
2881	select LEDS_CLASS
2882	help
2883	  This option enables system support for the Technologic Systems TS-5500.
2884
2885endif # X86_32
2886
2887config AMD_NB
2888	def_bool y
2889	depends on CPU_SUP_AMD && PCI
2890
2891endmenu
2892
2893menu "Binary Emulations"
2894
2895config IA32_EMULATION
2896	bool "IA32 Emulation"
2897	depends on X86_64
2898	select ARCH_WANT_OLD_COMPAT_IPC
2899	select BINFMT_ELF
2900	select COMPAT_OLD_SIGACTION
2901	help
2902	  Include code to run legacy 32-bit programs under a
2903	  64-bit kernel. You should likely turn this on, unless you're
2904	  100% sure that you don't have any 32-bit programs left.
2905
2906config X86_X32_ABI
2907	bool "x32 ABI for 64-bit mode"
2908	depends on X86_64
2909	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2910	# compressed debug sections to x86_x32 properly:
2911	# https://github.com/ClangBuiltLinux/linux/issues/514
2912	# https://github.com/ClangBuiltLinux/linux/issues/1141
2913	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2914	help
2915	  Include code to run binaries for the x32 native 32-bit ABI
2916	  for 64-bit processors.  An x32 process gets access to the
2917	  full 64-bit register file and wide data path while leaving
2918	  pointers at 32 bits for smaller memory footprint.
2919
2920config COMPAT_32
2921	def_bool y
2922	depends on IA32_EMULATION || X86_32
2923	select HAVE_UID16
2924	select OLD_SIGSUSPEND3
2925
2926config COMPAT
2927	def_bool y
2928	depends on IA32_EMULATION || X86_X32_ABI
2929
2930config COMPAT_FOR_U64_ALIGNMENT
2931	def_bool y
2932	depends on COMPAT
2933
2934endmenu
2935
2936config HAVE_ATOMIC_IOMAP
2937	def_bool y
2938	depends on X86_32
2939
2940source "arch/x86/kvm/Kconfig"
2941
2942source "arch/x86/Kconfig.assembler"
2943