xref: /openbmc/linux/arch/x86/Kconfig (revision 47010c04)
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 STACK_VALIDATION
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_KERNEL_BZIP2
217	select HAVE_KERNEL_GZIP
218	select HAVE_KERNEL_LZ4
219	select HAVE_KERNEL_LZMA
220	select HAVE_KERNEL_LZO
221	select HAVE_KERNEL_XZ
222	select HAVE_KERNEL_ZSTD
223	select HAVE_KPROBES
224	select HAVE_KPROBES_ON_FTRACE
225	select HAVE_FUNCTION_ERROR_INJECTION
226	select HAVE_KRETPROBES
227	select HAVE_RETHOOK
228	select HAVE_KVM
229	select HAVE_LIVEPATCH			if X86_64
230	select HAVE_MIXED_BREAKPOINTS_REGS
231	select HAVE_MOD_ARCH_SPECIFIC
232	select HAVE_MOVE_PMD
233	select HAVE_MOVE_PUD
234	select HAVE_NMI
235	select HAVE_OPTPROBES
236	select HAVE_PCSPKR_PLATFORM
237	select HAVE_PERF_EVENTS
238	select HAVE_PERF_EVENTS_NMI
239	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
240	select HAVE_PCI
241	select HAVE_PERF_REGS
242	select HAVE_PERF_USER_STACK_DUMP
243	select MMU_GATHER_RCU_TABLE_FREE		if PARAVIRT
244	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
245	select HAVE_REGS_AND_STACK_ACCESS_API
246	select HAVE_RELIABLE_STACKTRACE		if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
247	select HAVE_FUNCTION_ARG_ACCESS_API
248	select HAVE_SETUP_PER_CPU_AREA
249	select HAVE_SOFTIRQ_ON_OWN_STACK
250	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
251	select HAVE_STACK_VALIDATION		if X86_64
252	select HAVE_STATIC_CALL
253	select HAVE_STATIC_CALL_INLINE		if HAVE_STACK_VALIDATION
254	select HAVE_PREEMPT_DYNAMIC_CALL
255	select HAVE_RSEQ
256	select HAVE_SYSCALL_TRACEPOINTS
257	select HAVE_UNSTABLE_SCHED_CLOCK
258	select HAVE_USER_RETURN_NOTIFIER
259	select HAVE_GENERIC_VDSO
260	select HOTPLUG_SMT			if SMP
261	select IRQ_FORCED_THREADING
262	select NEED_PER_CPU_EMBED_FIRST_CHUNK
263	select NEED_PER_CPU_PAGE_FIRST_CHUNK
264	select NEED_SG_DMA_LENGTH
265	select PCI_DOMAINS			if PCI
266	select PCI_LOCKLESS_CONFIG		if PCI
267	select PERF_EVENTS
268	select RTC_LIB
269	select RTC_MC146818_LIB
270	select SPARSE_IRQ
271	select SRCU
272	select STACK_VALIDATION			if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
273	select SYSCTL_EXCEPTION_TRACE
274	select THREAD_INFO_IN_TASK
275	select TRACE_IRQFLAGS_SUPPORT
276	select USER_STACKTRACE_SUPPORT
277	select VIRT_TO_BUS
278	select HAVE_ARCH_KCSAN			if X86_64
279	select X86_FEATURE_NAMES		if PROC_FS
280	select PROC_PID_ARCH_STATUS		if PROC_FS
281	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
282	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
283
284config INSTRUCTION_DECODER
285	def_bool y
286	depends on KPROBES || PERF_EVENTS || UPROBES
287
288config OUTPUT_FORMAT
289	string
290	default "elf32-i386" if X86_32
291	default "elf64-x86-64" if X86_64
292
293config LOCKDEP_SUPPORT
294	def_bool y
295
296config STACKTRACE_SUPPORT
297	def_bool y
298
299config MMU
300	def_bool y
301
302config ARCH_MMAP_RND_BITS_MIN
303	default 28 if 64BIT
304	default 8
305
306config ARCH_MMAP_RND_BITS_MAX
307	default 32 if 64BIT
308	default 16
309
310config ARCH_MMAP_RND_COMPAT_BITS_MIN
311	default 8
312
313config ARCH_MMAP_RND_COMPAT_BITS_MAX
314	default 16
315
316config SBUS
317	bool
318
319config GENERIC_ISA_DMA
320	def_bool y
321	depends on ISA_DMA_API
322
323config GENERIC_BUG
324	def_bool y
325	depends on BUG
326	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
327
328config GENERIC_BUG_RELATIVE_POINTERS
329	bool
330
331config ARCH_MAY_HAVE_PC_FDC
332	def_bool y
333	depends on ISA_DMA_API
334
335config GENERIC_CALIBRATE_DELAY
336	def_bool y
337
338config ARCH_HAS_CPU_RELAX
339	def_bool y
340
341config ARCH_HIBERNATION_POSSIBLE
342	def_bool y
343
344config ARCH_NR_GPIO
345	int
346	default 1024 if X86_64
347	default 512
348
349config ARCH_SUSPEND_POSSIBLE
350	def_bool y
351
352config AUDIT_ARCH
353	def_bool y if X86_64
354
355config KASAN_SHADOW_OFFSET
356	hex
357	depends on KASAN
358	default 0xdffffc0000000000
359
360config HAVE_INTEL_TXT
361	def_bool y
362	depends on INTEL_IOMMU && ACPI
363
364config X86_32_SMP
365	def_bool y
366	depends on X86_32 && SMP
367
368config X86_64_SMP
369	def_bool y
370	depends on X86_64 && SMP
371
372config ARCH_SUPPORTS_UPROBES
373	def_bool y
374
375config FIX_EARLYCON_MEM
376	def_bool y
377
378config DYNAMIC_PHYSICAL_MASK
379	bool
380
381config PGTABLE_LEVELS
382	int
383	default 5 if X86_5LEVEL
384	default 4 if X86_64
385	default 3 if X86_PAE
386	default 2
387
388config CC_HAS_SANE_STACKPROTECTOR
389	bool
390	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
391	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
392	help
393	   We have to make sure stack protector is unconditionally disabled if
394	   the compiler produces broken code or if it does not let us control
395	   the segment on 32-bit kernels.
396
397menu "Processor type and features"
398
399config SMP
400	bool "Symmetric multi-processing support"
401	help
402	  This enables support for systems with more than one CPU. If you have
403	  a system with only one CPU, say N. If you have a system with more
404	  than one CPU, say Y.
405
406	  If you say N here, the kernel will run on uni- and multiprocessor
407	  machines, but will use only one CPU of a multiprocessor machine. If
408	  you say Y here, the kernel will run on many, but not all,
409	  uniprocessor machines. On a uniprocessor machine, the kernel
410	  will run faster if you say N here.
411
412	  Note that if you say Y here and choose architecture "586" or
413	  "Pentium" under "Processor family", the kernel will not work on 486
414	  architectures. Similarly, multiprocessor kernels for the "PPro"
415	  architecture may not work on all Pentium based boards.
416
417	  People using multiprocessor machines who say Y here should also say
418	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
419	  Management" code will be disabled if you say Y here.
420
421	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
422	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
423	  <http://www.tldp.org/docs.html#howto>.
424
425	  If you don't know what to do here, say N.
426
427config X86_FEATURE_NAMES
428	bool "Processor feature human-readable names" if EMBEDDED
429	default y
430	help
431	  This option compiles in a table of x86 feature bits and corresponding
432	  names.  This is required to support /proc/cpuinfo and a few kernel
433	  messages.  You can disable this to save space, at the expense of
434	  making those few kernel messages show numeric feature bits instead.
435
436	  If in doubt, say Y.
437
438config X86_X2APIC
439	bool "Support x2apic"
440	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
441	help
442	  This enables x2apic support on CPUs that have this feature.
443
444	  This allows 32-bit apic IDs (so it can support very large systems),
445	  and accesses the local apic via MSRs not via mmio.
446
447	  If you don't know what to do here, say N.
448
449config X86_MPPARSE
450	bool "Enable MPS table" if ACPI
451	default y
452	depends on X86_LOCAL_APIC
453	help
454	  For old smp systems that do not have proper acpi support. Newer systems
455	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
456
457config GOLDFISH
458	def_bool y
459	depends on X86_GOLDFISH
460
461config RETPOLINE
462	bool "Avoid speculative indirect branches in kernel"
463	default y
464	help
465	  Compile kernel with the retpoline compiler options to guard against
466	  kernel-to-user data leaks by avoiding speculative indirect
467	  branches. Requires a compiler with -mindirect-branch=thunk-extern
468	  support for full protection. The kernel may run slower.
469
470config CC_HAS_SLS
471	def_bool $(cc-option,-mharden-sls=all)
472
473config SLS
474	bool "Mitigate Straight-Line-Speculation"
475	depends on CC_HAS_SLS && X86_64
476	default n
477	help
478	  Compile the kernel with straight-line-speculation options to guard
479	  against straight line speculation. The kernel image might be slightly
480	  larger.
481
482config X86_CPU_RESCTRL
483	bool "x86 CPU resource control support"
484	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
485	select KERNFS
486	select PROC_CPU_RESCTRL		if PROC_FS
487	help
488	  Enable x86 CPU resource control support.
489
490	  Provide support for the allocation and monitoring of system resources
491	  usage by the CPU.
492
493	  Intel calls this Intel Resource Director Technology
494	  (Intel(R) RDT). More information about RDT can be found in the
495	  Intel x86 Architecture Software Developer Manual.
496
497	  AMD calls this AMD Platform Quality of Service (AMD QoS).
498	  More information about AMD QoS can be found in the AMD64 Technology
499	  Platform Quality of Service Extensions manual.
500
501	  Say N if unsure.
502
503if X86_32
504config X86_BIGSMP
505	bool "Support for big SMP systems with more than 8 CPUs"
506	depends on SMP
507	help
508	  This option is needed for the systems that have more than 8 CPUs.
509
510config X86_EXTENDED_PLATFORM
511	bool "Support for extended (non-PC) x86 platforms"
512	default y
513	help
514	  If you disable this option then the kernel will only support
515	  standard PC platforms. (which covers the vast majority of
516	  systems out there.)
517
518	  If you enable this option then you'll be able to select support
519	  for the following (non-PC) 32 bit x86 platforms:
520		Goldfish (Android emulator)
521		AMD Elan
522		RDC R-321x SoC
523		SGI 320/540 (Visual Workstation)
524		STA2X11-based (e.g. Northville)
525		Moorestown MID devices
526
527	  If you have one of these systems, or if you want to build a
528	  generic distribution kernel, say Y here - otherwise say N.
529endif
530
531if X86_64
532config X86_EXTENDED_PLATFORM
533	bool "Support for extended (non-PC) x86 platforms"
534	default y
535	help
536	  If you disable this option then the kernel will only support
537	  standard PC platforms. (which covers the vast majority of
538	  systems out there.)
539
540	  If you enable this option then you'll be able to select support
541	  for the following (non-PC) 64 bit x86 platforms:
542		Numascale NumaChip
543		ScaleMP vSMP
544		SGI Ultraviolet
545
546	  If you have one of these systems, or if you want to build a
547	  generic distribution kernel, say Y here - otherwise say N.
548endif
549# This is an alphabetically sorted list of 64 bit extended platforms
550# Please maintain the alphabetic order if and when there are additions
551config X86_NUMACHIP
552	bool "Numascale NumaChip"
553	depends on X86_64
554	depends on X86_EXTENDED_PLATFORM
555	depends on NUMA
556	depends on SMP
557	depends on X86_X2APIC
558	depends on PCI_MMCONFIG
559	help
560	  Adds support for Numascale NumaChip large-SMP systems. Needed to
561	  enable more than ~168 cores.
562	  If you don't have one of these, you should say N here.
563
564config X86_VSMP
565	bool "ScaleMP vSMP"
566	select HYPERVISOR_GUEST
567	select PARAVIRT
568	depends on X86_64 && PCI
569	depends on X86_EXTENDED_PLATFORM
570	depends on SMP
571	help
572	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
573	  supposed to run on these EM64T-based machines.  Only choose this option
574	  if you have one of these machines.
575
576config X86_UV
577	bool "SGI Ultraviolet"
578	depends on X86_64
579	depends on X86_EXTENDED_PLATFORM
580	depends on NUMA
581	depends on EFI
582	depends on KEXEC_CORE
583	depends on X86_X2APIC
584	depends on PCI
585	help
586	  This option is needed in order to support SGI Ultraviolet systems.
587	  If you don't have one of these, you should say N here.
588
589# Following is an alphabetically sorted list of 32 bit extended platforms
590# Please maintain the alphabetic order if and when there are additions
591
592config X86_GOLDFISH
593	bool "Goldfish (Virtual Platform)"
594	depends on X86_EXTENDED_PLATFORM
595	help
596	 Enable support for the Goldfish virtual platform used primarily
597	 for Android development. Unless you are building for the Android
598	 Goldfish emulator say N here.
599
600config X86_INTEL_CE
601	bool "CE4100 TV platform"
602	depends on PCI
603	depends on PCI_GODIRECT
604	depends on X86_IO_APIC
605	depends on X86_32
606	depends on X86_EXTENDED_PLATFORM
607	select X86_REBOOTFIXUPS
608	select OF
609	select OF_EARLY_FLATTREE
610	help
611	  Select for the Intel CE media processor (CE4100) SOC.
612	  This option compiles in support for the CE4100 SOC for settop
613	  boxes and media devices.
614
615config X86_INTEL_MID
616	bool "Intel MID platform support"
617	depends on X86_EXTENDED_PLATFORM
618	depends on X86_PLATFORM_DEVICES
619	depends on PCI
620	depends on X86_64 || (PCI_GOANY && X86_32)
621	depends on X86_IO_APIC
622	select I2C
623	select DW_APB_TIMER
624	select INTEL_SCU_PCI
625	help
626	  Select to build a kernel capable of supporting Intel MID (Mobile
627	  Internet Device) platform systems which do not have the PCI legacy
628	  interfaces. If you are building for a PC class system say N here.
629
630	  Intel MID platforms are based on an Intel processor and chipset which
631	  consume less power than most of the x86 derivatives.
632
633config X86_INTEL_QUARK
634	bool "Intel Quark platform support"
635	depends on X86_32
636	depends on X86_EXTENDED_PLATFORM
637	depends on X86_PLATFORM_DEVICES
638	depends on X86_TSC
639	depends on PCI
640	depends on PCI_GOANY
641	depends on X86_IO_APIC
642	select IOSF_MBI
643	select INTEL_IMR
644	select COMMON_CLK
645	help
646	  Select to include support for Quark X1000 SoC.
647	  Say Y here if you have a Quark based system such as the Arduino
648	  compatible Intel Galileo.
649
650config X86_INTEL_LPSS
651	bool "Intel Low Power Subsystem Support"
652	depends on X86 && ACPI && PCI
653	select COMMON_CLK
654	select PINCTRL
655	select IOSF_MBI
656	help
657	  Select to build support for Intel Low Power Subsystem such as
658	  found on Intel Lynxpoint PCH. Selecting this option enables
659	  things like clock tree (common clock framework) and pincontrol
660	  which are needed by the LPSS peripheral drivers.
661
662config X86_AMD_PLATFORM_DEVICE
663	bool "AMD ACPI2Platform devices support"
664	depends on ACPI
665	select COMMON_CLK
666	select PINCTRL
667	help
668	  Select to interpret AMD specific ACPI device to platform device
669	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
670	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
671	  implemented under PINCTRL subsystem.
672
673config IOSF_MBI
674	tristate "Intel SoC IOSF Sideband support for SoC platforms"
675	depends on PCI
676	help
677	  This option enables sideband register access support for Intel SoC
678	  platforms. On these platforms the IOSF sideband is used in lieu of
679	  MSR's for some register accesses, mostly but not limited to thermal
680	  and power. Drivers may query the availability of this device to
681	  determine if they need the sideband in order to work on these
682	  platforms. The sideband is available on the following SoC products.
683	  This list is not meant to be exclusive.
684	   - BayTrail
685	   - Braswell
686	   - Quark
687
688	  You should say Y if you are running a kernel on one of these SoC's.
689
690config IOSF_MBI_DEBUG
691	bool "Enable IOSF sideband access through debugfs"
692	depends on IOSF_MBI && DEBUG_FS
693	help
694	  Select this option to expose the IOSF sideband access registers (MCR,
695	  MDR, MCRX) through debugfs to write and read register information from
696	  different units on the SoC. This is most useful for obtaining device
697	  state information for debug and analysis. As this is a general access
698	  mechanism, users of this option would have specific knowledge of the
699	  device they want to access.
700
701	  If you don't require the option or are in doubt, say N.
702
703config X86_RDC321X
704	bool "RDC R-321x SoC"
705	depends on X86_32
706	depends on X86_EXTENDED_PLATFORM
707	select M486
708	select X86_REBOOTFIXUPS
709	help
710	  This option is needed for RDC R-321x system-on-chip, also known
711	  as R-8610-(G).
712	  If you don't have one of these chips, you should say N here.
713
714config X86_32_NON_STANDARD
715	bool "Support non-standard 32-bit SMP architectures"
716	depends on X86_32 && SMP
717	depends on X86_EXTENDED_PLATFORM
718	help
719	  This option compiles in the bigsmp and STA2X11 default
720	  subarchitectures.  It is intended for a generic binary
721	  kernel. If you select them all, kernel will probe it one by
722	  one and will fallback to default.
723
724# Alphabetically sorted list of Non standard 32 bit platforms
725
726config X86_SUPPORTS_MEMORY_FAILURE
727	def_bool y
728	# MCE code calls memory_failure():
729	depends on X86_MCE
730	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
731	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
732	depends on X86_64 || !SPARSEMEM
733	select ARCH_SUPPORTS_MEMORY_FAILURE
734
735config STA2X11
736	bool "STA2X11 Companion Chip Support"
737	depends on X86_32_NON_STANDARD && PCI
738	select SWIOTLB
739	select MFD_STA2X11
740	select GPIOLIB
741	help
742	  This adds support for boards based on the STA2X11 IO-Hub,
743	  a.k.a. "ConneXt". The chip is used in place of the standard
744	  PC chipset, so all "standard" peripherals are missing. If this
745	  option is selected the kernel will still be able to boot on
746	  standard PC machines.
747
748config X86_32_IRIS
749	tristate "Eurobraille/Iris poweroff module"
750	depends on X86_32
751	help
752	  The Iris machines from EuroBraille do not have APM or ACPI support
753	  to shut themselves down properly.  A special I/O sequence is
754	  needed to do so, which is what this module does at
755	  kernel shutdown.
756
757	  This is only for Iris machines from EuroBraille.
758
759	  If unused, say N.
760
761config SCHED_OMIT_FRAME_POINTER
762	def_bool y
763	prompt "Single-depth WCHAN output"
764	depends on X86
765	help
766	  Calculate simpler /proc/<PID>/wchan values. If this option
767	  is disabled then wchan values will recurse back to the
768	  caller function. This provides more accurate wchan values,
769	  at the expense of slightly more scheduling overhead.
770
771	  If in doubt, say "Y".
772
773menuconfig HYPERVISOR_GUEST
774	bool "Linux guest support"
775	help
776	  Say Y here to enable options for running Linux under various hyper-
777	  visors. This option enables basic hypervisor detection and platform
778	  setup.
779
780	  If you say N, all options in this submenu will be skipped and
781	  disabled, and Linux guest support won't be built in.
782
783if HYPERVISOR_GUEST
784
785config PARAVIRT
786	bool "Enable paravirtualization code"
787	depends on HAVE_STATIC_CALL
788	help
789	  This changes the kernel so it can modify itself when it is run
790	  under a hypervisor, potentially improving performance significantly
791	  over full virtualization.  However, when run without a hypervisor
792	  the kernel is theoretically slower and slightly larger.
793
794config PARAVIRT_XXL
795	bool
796
797config PARAVIRT_DEBUG
798	bool "paravirt-ops debugging"
799	depends on PARAVIRT && DEBUG_KERNEL
800	help
801	  Enable to debug paravirt_ops internals.  Specifically, BUG if
802	  a paravirt_op is missing when it is called.
803
804config PARAVIRT_SPINLOCKS
805	bool "Paravirtualization layer for spinlocks"
806	depends on PARAVIRT && SMP
807	help
808	  Paravirtualized spinlocks allow a pvops backend to replace the
809	  spinlock implementation with something virtualization-friendly
810	  (for example, block the virtual CPU rather than spinning).
811
812	  It has a minimal impact on native kernels and gives a nice performance
813	  benefit on paravirtualized KVM / Xen kernels.
814
815	  If you are unsure how to answer this question, answer Y.
816
817config X86_HV_CALLBACK_VECTOR
818	def_bool n
819
820source "arch/x86/xen/Kconfig"
821
822config KVM_GUEST
823	bool "KVM Guest support (including kvmclock)"
824	depends on PARAVIRT
825	select PARAVIRT_CLOCK
826	select ARCH_CPUIDLE_HALTPOLL
827	select X86_HV_CALLBACK_VECTOR
828	default y
829	help
830	  This option enables various optimizations for running under the KVM
831	  hypervisor. It includes a paravirtualized clock, so that instead
832	  of relying on a PIT (or probably other) emulation by the
833	  underlying device model, the host provides the guest with
834	  timing infrastructure such as time of day, and system time
835
836config ARCH_CPUIDLE_HALTPOLL
837	def_bool n
838	prompt "Disable host haltpoll when loading haltpoll driver"
839	help
840	  If virtualized under KVM, disable host haltpoll.
841
842config PVH
843	bool "Support for running PVH guests"
844	help
845	  This option enables the PVH entry point for guest virtual machines
846	  as specified in the x86/HVM direct boot ABI.
847
848config PARAVIRT_TIME_ACCOUNTING
849	bool "Paravirtual steal time accounting"
850	depends on PARAVIRT
851	help
852	  Select this option to enable fine granularity task steal time
853	  accounting. Time spent executing other tasks in parallel with
854	  the current vCPU is discounted from the vCPU power. To account for
855	  that, there can be a small performance impact.
856
857	  If in doubt, say N here.
858
859config PARAVIRT_CLOCK
860	bool
861
862config JAILHOUSE_GUEST
863	bool "Jailhouse non-root cell support"
864	depends on X86_64 && PCI
865	select X86_PM_TIMER
866	help
867	  This option allows to run Linux as guest in a Jailhouse non-root
868	  cell. You can leave this option disabled if you only want to start
869	  Jailhouse and run Linux afterwards in the root cell.
870
871config ACRN_GUEST
872	bool "ACRN Guest support"
873	depends on X86_64
874	select X86_HV_CALLBACK_VECTOR
875	help
876	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
877	  a flexible, lightweight reference open-source hypervisor, built with
878	  real-time and safety-criticality in mind. It is built for embedded
879	  IOT with small footprint and real-time features. More details can be
880	  found in https://projectacrn.org/.
881
882endif #HYPERVISOR_GUEST
883
884source "arch/x86/Kconfig.cpu"
885
886config HPET_TIMER
887	def_bool X86_64
888	prompt "HPET Timer Support" if X86_32
889	help
890	  Use the IA-PC HPET (High Precision Event Timer) to manage
891	  time in preference to the PIT and RTC, if a HPET is
892	  present.
893	  HPET is the next generation timer replacing legacy 8254s.
894	  The HPET provides a stable time base on SMP
895	  systems, unlike the TSC, but it is more expensive to access,
896	  as it is off-chip.  The interface used is documented
897	  in the HPET spec, revision 1.
898
899	  You can safely choose Y here.  However, HPET will only be
900	  activated if the platform and the BIOS support this feature.
901	  Otherwise the 8254 will be used for timing services.
902
903	  Choose N to continue using the legacy 8254 timer.
904
905config HPET_EMULATE_RTC
906	def_bool y
907	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
908
909# Mark as expert because too many people got it wrong.
910# The code disables itself when not needed.
911config DMI
912	default y
913	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
914	bool "Enable DMI scanning" if EXPERT
915	help
916	  Enabled scanning of DMI to identify machine quirks. Say Y
917	  here unless you have verified that your setup is not
918	  affected by entries in the DMI blacklist. Required by PNP
919	  BIOS code.
920
921config GART_IOMMU
922	bool "Old AMD GART IOMMU support"
923	select DMA_OPS
924	select IOMMU_HELPER
925	select SWIOTLB
926	depends on X86_64 && PCI && AMD_NB
927	help
928	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
929	  GART based hardware IOMMUs.
930
931	  The GART supports full DMA access for devices with 32-bit access
932	  limitations, on systems with more than 3 GB. This is usually needed
933	  for USB, sound, many IDE/SATA chipsets and some other devices.
934
935	  Newer systems typically have a modern AMD IOMMU, supported via
936	  the CONFIG_AMD_IOMMU=y config option.
937
938	  In normal configurations this driver is only active when needed:
939	  there's more than 3 GB of memory and the system contains a
940	  32-bit limited device.
941
942	  If unsure, say Y.
943
944config MAXSMP
945	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
946	depends on X86_64 && SMP && DEBUG_KERNEL
947	select CPUMASK_OFFSTACK
948	help
949	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
950	  If unsure, say N.
951
952#
953# The maximum number of CPUs supported:
954#
955# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
956# and which can be configured interactively in the
957# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
958#
959# The ranges are different on 32-bit and 64-bit kernels, depending on
960# hardware capabilities and scalability features of the kernel.
961#
962# ( If MAXSMP is enabled we just use the highest possible value and disable
963#   interactive configuration. )
964#
965
966config NR_CPUS_RANGE_BEGIN
967	int
968	default NR_CPUS_RANGE_END if MAXSMP
969	default    1 if !SMP
970	default    2
971
972config NR_CPUS_RANGE_END
973	int
974	depends on X86_32
975	default   64 if  SMP &&  X86_BIGSMP
976	default    8 if  SMP && !X86_BIGSMP
977	default    1 if !SMP
978
979config NR_CPUS_RANGE_END
980	int
981	depends on X86_64
982	default 8192 if  SMP && CPUMASK_OFFSTACK
983	default  512 if  SMP && !CPUMASK_OFFSTACK
984	default    1 if !SMP
985
986config NR_CPUS_DEFAULT
987	int
988	depends on X86_32
989	default   32 if  X86_BIGSMP
990	default    8 if  SMP
991	default    1 if !SMP
992
993config NR_CPUS_DEFAULT
994	int
995	depends on X86_64
996	default 8192 if  MAXSMP
997	default   64 if  SMP
998	default    1 if !SMP
999
1000config NR_CPUS
1001	int "Maximum number of CPUs" if SMP && !MAXSMP
1002	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1003	default NR_CPUS_DEFAULT
1004	help
1005	  This allows you to specify the maximum number of CPUs which this
1006	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1007	  supported value is 8192, otherwise the maximum value is 512.  The
1008	  minimum value which makes sense is 2.
1009
1010	  This is purely to save memory: each supported CPU adds about 8KB
1011	  to the kernel image.
1012
1013config SCHED_CLUSTER
1014	bool "Cluster scheduler support"
1015	depends on SMP
1016	default y
1017	help
1018	  Cluster scheduler support improves the CPU scheduler's decision
1019	  making when dealing with machines that have clusters of CPUs.
1020	  Cluster usually means a couple of CPUs which are placed closely
1021	  by sharing mid-level caches, last-level cache tags or internal
1022	  busses.
1023
1024config SCHED_SMT
1025	def_bool y if SMP
1026
1027config SCHED_MC
1028	def_bool y
1029	prompt "Multi-core scheduler support"
1030	depends on SMP
1031	help
1032	  Multi-core scheduler support improves the CPU scheduler's decision
1033	  making when dealing with multi-core CPU chips at a cost of slightly
1034	  increased overhead in some places. If unsure say N here.
1035
1036config SCHED_MC_PRIO
1037	bool "CPU core priorities scheduler support"
1038	depends on SCHED_MC && CPU_SUP_INTEL
1039	select X86_INTEL_PSTATE
1040	select CPU_FREQ
1041	default y
1042	help
1043	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1044	  core ordering determined at manufacturing time, which allows
1045	  certain cores to reach higher turbo frequencies (when running
1046	  single threaded workloads) than others.
1047
1048	  Enabling this kernel feature teaches the scheduler about
1049	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1050	  scheduler's CPU selection logic accordingly, so that higher
1051	  overall system performance can be achieved.
1052
1053	  This feature will have no effect on CPUs without this feature.
1054
1055	  If unsure say Y here.
1056
1057config UP_LATE_INIT
1058	def_bool y
1059	depends on !SMP && X86_LOCAL_APIC
1060
1061config X86_UP_APIC
1062	bool "Local APIC support on uniprocessors" if !PCI_MSI
1063	default PCI_MSI
1064	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1065	help
1066	  A local APIC (Advanced Programmable Interrupt Controller) is an
1067	  integrated interrupt controller in the CPU. If you have a single-CPU
1068	  system which has a processor with a local APIC, you can say Y here to
1069	  enable and use it. If you say Y here even though your machine doesn't
1070	  have a local APIC, then the kernel will still run with no slowdown at
1071	  all. The local APIC supports CPU-generated self-interrupts (timer,
1072	  performance counters), and the NMI watchdog which detects hard
1073	  lockups.
1074
1075config X86_UP_IOAPIC
1076	bool "IO-APIC support on uniprocessors"
1077	depends on X86_UP_APIC
1078	help
1079	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1080	  SMP-capable replacement for PC-style interrupt controllers. Most
1081	  SMP systems and many recent uniprocessor systems have one.
1082
1083	  If you have a single-CPU system with an IO-APIC, you can say Y here
1084	  to use it. If you say Y here even though your machine doesn't have
1085	  an IO-APIC, then the kernel will still run with no slowdown at all.
1086
1087config X86_LOCAL_APIC
1088	def_bool y
1089	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1090	select IRQ_DOMAIN_HIERARCHY
1091	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1092
1093config X86_IO_APIC
1094	def_bool y
1095	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1096
1097config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1098	bool "Reroute for broken boot IRQs"
1099	depends on X86_IO_APIC
1100	help
1101	  This option enables a workaround that fixes a source of
1102	  spurious interrupts. This is recommended when threaded
1103	  interrupt handling is used on systems where the generation of
1104	  superfluous "boot interrupts" cannot be disabled.
1105
1106	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1107	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1108	  kernel does during interrupt handling). On chipsets where this
1109	  boot IRQ generation cannot be disabled, this workaround keeps
1110	  the original IRQ line masked so that only the equivalent "boot
1111	  IRQ" is delivered to the CPUs. The workaround also tells the
1112	  kernel to set up the IRQ handler on the boot IRQ line. In this
1113	  way only one interrupt is delivered to the kernel. Otherwise
1114	  the spurious second interrupt may cause the kernel to bring
1115	  down (vital) interrupt lines.
1116
1117	  Only affects "broken" chipsets. Interrupt sharing may be
1118	  increased on these systems.
1119
1120config X86_MCE
1121	bool "Machine Check / overheating reporting"
1122	select GENERIC_ALLOCATOR
1123	default y
1124	help
1125	  Machine Check support allows the processor to notify the
1126	  kernel if it detects a problem (e.g. overheating, data corruption).
1127	  The action the kernel takes depends on the severity of the problem,
1128	  ranging from warning messages to halting the machine.
1129
1130config X86_MCELOG_LEGACY
1131	bool "Support for deprecated /dev/mcelog character device"
1132	depends on X86_MCE
1133	help
1134	  Enable support for /dev/mcelog which is needed by the old mcelog
1135	  userspace logging daemon. Consider switching to the new generation
1136	  rasdaemon solution.
1137
1138config X86_MCE_INTEL
1139	def_bool y
1140	prompt "Intel MCE features"
1141	depends on X86_MCE && X86_LOCAL_APIC
1142	help
1143	   Additional support for intel specific MCE features such as
1144	   the thermal monitor.
1145
1146config X86_MCE_AMD
1147	def_bool y
1148	prompt "AMD MCE features"
1149	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1150	help
1151	   Additional support for AMD specific MCE features such as
1152	   the DRAM Error Threshold.
1153
1154config X86_ANCIENT_MCE
1155	bool "Support for old Pentium 5 / WinChip machine checks"
1156	depends on X86_32 && X86_MCE
1157	help
1158	  Include support for machine check handling on old Pentium 5 or WinChip
1159	  systems. These typically need to be enabled explicitly on the command
1160	  line.
1161
1162config X86_MCE_THRESHOLD
1163	depends on X86_MCE_AMD || X86_MCE_INTEL
1164	def_bool y
1165
1166config X86_MCE_INJECT
1167	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1168	tristate "Machine check injector support"
1169	help
1170	  Provide support for injecting machine checks for testing purposes.
1171	  If you don't know what a machine check is and you don't do kernel
1172	  QA it is safe to say n.
1173
1174source "arch/x86/events/Kconfig"
1175
1176config X86_LEGACY_VM86
1177	bool "Legacy VM86 support"
1178	depends on X86_32
1179	help
1180	  This option allows user programs to put the CPU into V8086
1181	  mode, which is an 80286-era approximation of 16-bit real mode.
1182
1183	  Some very old versions of X and/or vbetool require this option
1184	  for user mode setting.  Similarly, DOSEMU will use it if
1185	  available to accelerate real mode DOS programs.  However, any
1186	  recent version of DOSEMU, X, or vbetool should be fully
1187	  functional even without kernel VM86 support, as they will all
1188	  fall back to software emulation. Nevertheless, if you are using
1189	  a 16-bit DOS program where 16-bit performance matters, vm86
1190	  mode might be faster than emulation and you might want to
1191	  enable this option.
1192
1193	  Note that any app that works on a 64-bit kernel is unlikely to
1194	  need this option, as 64-bit kernels don't, and can't, support
1195	  V8086 mode. This option is also unrelated to 16-bit protected
1196	  mode and is not needed to run most 16-bit programs under Wine.
1197
1198	  Enabling this option increases the complexity of the kernel
1199	  and slows down exception handling a tiny bit.
1200
1201	  If unsure, say N here.
1202
1203config VM86
1204	bool
1205	default X86_LEGACY_VM86
1206
1207config X86_16BIT
1208	bool "Enable support for 16-bit segments" if EXPERT
1209	default y
1210	depends on MODIFY_LDT_SYSCALL
1211	help
1212	  This option is required by programs like Wine to run 16-bit
1213	  protected mode legacy code on x86 processors.  Disabling
1214	  this option saves about 300 bytes on i386, or around 6K text
1215	  plus 16K runtime memory on x86-64,
1216
1217config X86_ESPFIX32
1218	def_bool y
1219	depends on X86_16BIT && X86_32
1220
1221config X86_ESPFIX64
1222	def_bool y
1223	depends on X86_16BIT && X86_64
1224
1225config X86_VSYSCALL_EMULATION
1226	bool "Enable vsyscall emulation" if EXPERT
1227	default y
1228	depends on X86_64
1229	help
1230	 This enables emulation of the legacy vsyscall page.  Disabling
1231	 it is roughly equivalent to booting with vsyscall=none, except
1232	 that it will also disable the helpful warning if a program
1233	 tries to use a vsyscall.  With this option set to N, offending
1234	 programs will just segfault, citing addresses of the form
1235	 0xffffffffff600?00.
1236
1237	 This option is required by many programs built before 2013, and
1238	 care should be used even with newer programs if set to N.
1239
1240	 Disabling this option saves about 7K of kernel size and
1241	 possibly 4K of additional runtime pagetable memory.
1242
1243config X86_IOPL_IOPERM
1244	bool "IOPERM and IOPL Emulation"
1245	default y
1246	help
1247	  This enables the ioperm() and iopl() syscalls which are necessary
1248	  for legacy applications.
1249
1250	  Legacy IOPL support is an overbroad mechanism which allows user
1251	  space aside of accessing all 65536 I/O ports also to disable
1252	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1253	  capabilities and permission from potentially active security
1254	  modules.
1255
1256	  The emulation restricts the functionality of the syscall to
1257	  only allowing the full range I/O port access, but prevents the
1258	  ability to disable interrupts from user space which would be
1259	  granted if the hardware IOPL mechanism would be used.
1260
1261config TOSHIBA
1262	tristate "Toshiba Laptop support"
1263	depends on X86_32
1264	help
1265	  This adds a driver to safely access the System Management Mode of
1266	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1267	  not work on models with a Phoenix BIOS. The System Management Mode
1268	  is used to set the BIOS and power saving options on Toshiba portables.
1269
1270	  For information on utilities to make use of this driver see the
1271	  Toshiba Linux utilities web site at:
1272	  <http://www.buzzard.org.uk/toshiba/>.
1273
1274	  Say Y if you intend to run this kernel on a Toshiba portable.
1275	  Say N otherwise.
1276
1277config X86_REBOOTFIXUPS
1278	bool "Enable X86 board specific fixups for reboot"
1279	depends on X86_32
1280	help
1281	  This enables chipset and/or board specific fixups to be done
1282	  in order to get reboot to work correctly. This is only needed on
1283	  some combinations of hardware and BIOS. The symptom, for which
1284	  this config is intended, is when reboot ends with a stalled/hung
1285	  system.
1286
1287	  Currently, the only fixup is for the Geode machines using
1288	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1289
1290	  Say Y if you want to enable the fixup. Currently, it's safe to
1291	  enable this option even if you don't need it.
1292	  Say N otherwise.
1293
1294config MICROCODE
1295	bool "CPU microcode loading support"
1296	default y
1297	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1298	help
1299	  If you say Y here, you will be able to update the microcode on
1300	  Intel and AMD processors. The Intel support is for the IA32 family,
1301	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1302	  AMD support is for families 0x10 and later. You will obviously need
1303	  the actual microcode binary data itself which is not shipped with
1304	  the Linux kernel.
1305
1306	  The preferred method to load microcode from a detached initrd is described
1307	  in Documentation/x86/microcode.rst. For that you need to enable
1308	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1309	  initrd for microcode blobs.
1310
1311	  In addition, you can build the microcode into the kernel. For that you
1312	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1313	  config option.
1314
1315config MICROCODE_INTEL
1316	bool "Intel microcode loading support"
1317	depends on MICROCODE
1318	default MICROCODE
1319	help
1320	  This options enables microcode patch loading support for Intel
1321	  processors.
1322
1323	  For the current Intel microcode data package go to
1324	  <https://downloadcenter.intel.com> and search for
1325	  'Linux Processor Microcode Data File'.
1326
1327config MICROCODE_AMD
1328	bool "AMD microcode loading support"
1329	depends on MICROCODE
1330	help
1331	  If you select this option, microcode patch loading support for AMD
1332	  processors will be enabled.
1333
1334config MICROCODE_OLD_INTERFACE
1335	bool "Ancient loading interface (DEPRECATED)"
1336	default n
1337	depends on MICROCODE
1338	help
1339	  DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1340	  which was used by userspace tools like iucode_tool and microcode.ctl.
1341	  It is inadequate because it runs too late to be able to properly
1342	  load microcode on a machine and it needs special tools. Instead, you
1343	  should've switched to the early loading method with the initrd or
1344	  builtin microcode by now: Documentation/x86/microcode.rst
1345
1346config X86_MSR
1347	tristate "/dev/cpu/*/msr - Model-specific register support"
1348	help
1349	  This device gives privileged processes access to the x86
1350	  Model-Specific Registers (MSRs).  It is a character device with
1351	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1352	  MSR accesses are directed to a specific CPU on multi-processor
1353	  systems.
1354
1355config X86_CPUID
1356	tristate "/dev/cpu/*/cpuid - CPU information support"
1357	help
1358	  This device gives processes access to the x86 CPUID instruction to
1359	  be executed on a specific processor.  It is a character device
1360	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1361	  /dev/cpu/31/cpuid.
1362
1363choice
1364	prompt "High Memory Support"
1365	default HIGHMEM4G
1366	depends on X86_32
1367
1368config NOHIGHMEM
1369	bool "off"
1370	help
1371	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1372	  However, the address space of 32-bit x86 processors is only 4
1373	  Gigabytes large. That means that, if you have a large amount of
1374	  physical memory, not all of it can be "permanently mapped" by the
1375	  kernel. The physical memory that's not permanently mapped is called
1376	  "high memory".
1377
1378	  If you are compiling a kernel which will never run on a machine with
1379	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1380	  choice and suitable for most users). This will result in a "3GB/1GB"
1381	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1382	  space and the remaining part of the 4GB virtual memory space is used
1383	  by the kernel to permanently map as much physical memory as
1384	  possible.
1385
1386	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1387	  answer "4GB" here.
1388
1389	  If more than 4 Gigabytes is used then answer "64GB" here. This
1390	  selection turns Intel PAE (Physical Address Extension) mode on.
1391	  PAE implements 3-level paging on IA32 processors. PAE is fully
1392	  supported by Linux, PAE mode is implemented on all recent Intel
1393	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1394	  then the kernel will not boot on CPUs that don't support PAE!
1395
1396	  The actual amount of total physical memory will either be
1397	  auto detected or can be forced by using a kernel command line option
1398	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1399	  your boot loader (lilo or loadlin) about how to pass options to the
1400	  kernel at boot time.)
1401
1402	  If unsure, say "off".
1403
1404config HIGHMEM4G
1405	bool "4GB"
1406	help
1407	  Select this if you have a 32-bit processor and between 1 and 4
1408	  gigabytes of physical RAM.
1409
1410config HIGHMEM64G
1411	bool "64GB"
1412	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1413	select X86_PAE
1414	help
1415	  Select this if you have a 32-bit processor and more than 4
1416	  gigabytes of physical RAM.
1417
1418endchoice
1419
1420choice
1421	prompt "Memory split" if EXPERT
1422	default VMSPLIT_3G
1423	depends on X86_32
1424	help
1425	  Select the desired split between kernel and user memory.
1426
1427	  If the address range available to the kernel is less than the
1428	  physical memory installed, the remaining memory will be available
1429	  as "high memory". Accessing high memory is a little more costly
1430	  than low memory, as it needs to be mapped into the kernel first.
1431	  Note that increasing the kernel address space limits the range
1432	  available to user programs, making the address space there
1433	  tighter.  Selecting anything other than the default 3G/1G split
1434	  will also likely make your kernel incompatible with binary-only
1435	  kernel modules.
1436
1437	  If you are not absolutely sure what you are doing, leave this
1438	  option alone!
1439
1440	config VMSPLIT_3G
1441		bool "3G/1G user/kernel split"
1442	config VMSPLIT_3G_OPT
1443		depends on !X86_PAE
1444		bool "3G/1G user/kernel split (for full 1G low memory)"
1445	config VMSPLIT_2G
1446		bool "2G/2G user/kernel split"
1447	config VMSPLIT_2G_OPT
1448		depends on !X86_PAE
1449		bool "2G/2G user/kernel split (for full 2G low memory)"
1450	config VMSPLIT_1G
1451		bool "1G/3G user/kernel split"
1452endchoice
1453
1454config PAGE_OFFSET
1455	hex
1456	default 0xB0000000 if VMSPLIT_3G_OPT
1457	default 0x80000000 if VMSPLIT_2G
1458	default 0x78000000 if VMSPLIT_2G_OPT
1459	default 0x40000000 if VMSPLIT_1G
1460	default 0xC0000000
1461	depends on X86_32
1462
1463config HIGHMEM
1464	def_bool y
1465	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1466
1467config X86_PAE
1468	bool "PAE (Physical Address Extension) Support"
1469	depends on X86_32 && !HIGHMEM4G
1470	select PHYS_ADDR_T_64BIT
1471	select SWIOTLB
1472	help
1473	  PAE is required for NX support, and furthermore enables
1474	  larger swapspace support for non-overcommit purposes. It
1475	  has the cost of more pagetable lookup overhead, and also
1476	  consumes more pagetable space per process.
1477
1478config X86_5LEVEL
1479	bool "Enable 5-level page tables support"
1480	default y
1481	select DYNAMIC_MEMORY_LAYOUT
1482	select SPARSEMEM_VMEMMAP
1483	depends on X86_64
1484	help
1485	  5-level paging enables access to larger address space:
1486	  upto 128 PiB of virtual address space and 4 PiB of
1487	  physical address space.
1488
1489	  It will be supported by future Intel CPUs.
1490
1491	  A kernel with the option enabled can be booted on machines that
1492	  support 4- or 5-level paging.
1493
1494	  See Documentation/x86/x86_64/5level-paging.rst for more
1495	  information.
1496
1497	  Say N if unsure.
1498
1499config X86_DIRECT_GBPAGES
1500	def_bool y
1501	depends on X86_64
1502	help
1503	  Certain kernel features effectively disable kernel
1504	  linear 1 GB mappings (even if the CPU otherwise
1505	  supports them), so don't confuse the user by printing
1506	  that we have them enabled.
1507
1508config X86_CPA_STATISTICS
1509	bool "Enable statistic for Change Page Attribute"
1510	depends on DEBUG_FS
1511	help
1512	  Expose statistics about the Change Page Attribute mechanism, which
1513	  helps to determine the effectiveness of preserving large and huge
1514	  page mappings when mapping protections are changed.
1515
1516config X86_MEM_ENCRYPT
1517	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1518	select DYNAMIC_PHYSICAL_MASK
1519	select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1520	def_bool n
1521
1522config AMD_MEM_ENCRYPT
1523	bool "AMD Secure Memory Encryption (SME) support"
1524	depends on X86_64 && CPU_SUP_AMD
1525	select DMA_COHERENT_POOL
1526	select ARCH_USE_MEMREMAP_PROT
1527	select INSTRUCTION_DECODER
1528	select ARCH_HAS_CC_PLATFORM
1529	select X86_MEM_ENCRYPT
1530	help
1531	  Say yes to enable support for the encryption of system memory.
1532	  This requires an AMD processor that supports Secure Memory
1533	  Encryption (SME).
1534
1535config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1536	bool "Activate AMD Secure Memory Encryption (SME) by default"
1537	depends on AMD_MEM_ENCRYPT
1538	help
1539	  Say yes to have system memory encrypted by default if running on
1540	  an AMD processor that supports Secure Memory Encryption (SME).
1541
1542	  If set to Y, then the encryption of system memory can be
1543	  deactivated with the mem_encrypt=off command line option.
1544
1545	  If set to N, then the encryption of system memory can be
1546	  activated with the mem_encrypt=on command line option.
1547
1548# Common NUMA Features
1549config NUMA
1550	bool "NUMA Memory Allocation and Scheduler Support"
1551	depends on SMP
1552	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1553	default y if X86_BIGSMP
1554	select USE_PERCPU_NUMA_NODE_ID
1555	help
1556	  Enable NUMA (Non-Uniform Memory Access) support.
1557
1558	  The kernel will try to allocate memory used by a CPU on the
1559	  local memory controller of the CPU and add some more
1560	  NUMA awareness to the kernel.
1561
1562	  For 64-bit this is recommended if the system is Intel Core i7
1563	  (or later), AMD Opteron, or EM64T NUMA.
1564
1565	  For 32-bit this is only needed if you boot a 32-bit
1566	  kernel on a 64-bit NUMA platform.
1567
1568	  Otherwise, you should say N.
1569
1570config AMD_NUMA
1571	def_bool y
1572	prompt "Old style AMD Opteron NUMA detection"
1573	depends on X86_64 && NUMA && PCI
1574	help
1575	  Enable AMD NUMA node topology detection.  You should say Y here if
1576	  you have a multi processor AMD system. This uses an old method to
1577	  read the NUMA configuration directly from the builtin Northbridge
1578	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1579	  which also takes priority if both are compiled in.
1580
1581config X86_64_ACPI_NUMA
1582	def_bool y
1583	prompt "ACPI NUMA detection"
1584	depends on X86_64 && NUMA && ACPI && PCI
1585	select ACPI_NUMA
1586	help
1587	  Enable ACPI SRAT based node topology detection.
1588
1589config NUMA_EMU
1590	bool "NUMA emulation"
1591	depends on NUMA
1592	help
1593	  Enable NUMA emulation. A flat machine will be split
1594	  into virtual nodes when booted with "numa=fake=N", where N is the
1595	  number of nodes. This is only useful for debugging.
1596
1597config NODES_SHIFT
1598	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1599	range 1 10
1600	default "10" if MAXSMP
1601	default "6" if X86_64
1602	default "3"
1603	depends on NUMA
1604	help
1605	  Specify the maximum number of NUMA Nodes available on the target
1606	  system.  Increases memory reserved to accommodate various tables.
1607
1608config ARCH_FLATMEM_ENABLE
1609	def_bool y
1610	depends on X86_32 && !NUMA
1611
1612config ARCH_SPARSEMEM_ENABLE
1613	def_bool y
1614	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1615	select SPARSEMEM_STATIC if X86_32
1616	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1617
1618config ARCH_SPARSEMEM_DEFAULT
1619	def_bool X86_64 || (NUMA && X86_32)
1620
1621config ARCH_SELECT_MEMORY_MODEL
1622	def_bool y
1623	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1624
1625config ARCH_MEMORY_PROBE
1626	bool "Enable sysfs memory/probe interface"
1627	depends on MEMORY_HOTPLUG
1628	help
1629	  This option enables a sysfs memory/probe interface for testing.
1630	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1631	  If you are unsure how to answer this question, answer N.
1632
1633config ARCH_PROC_KCORE_TEXT
1634	def_bool y
1635	depends on X86_64 && PROC_KCORE
1636
1637config ILLEGAL_POINTER_VALUE
1638	hex
1639	default 0 if X86_32
1640	default 0xdead000000000000 if X86_64
1641
1642config X86_PMEM_LEGACY_DEVICE
1643	bool
1644
1645config X86_PMEM_LEGACY
1646	tristate "Support non-standard NVDIMMs and ADR protected memory"
1647	depends on PHYS_ADDR_T_64BIT
1648	depends on BLK_DEV
1649	select X86_PMEM_LEGACY_DEVICE
1650	select NUMA_KEEP_MEMINFO if NUMA
1651	select LIBNVDIMM
1652	help
1653	  Treat memory marked using the non-standard e820 type of 12 as used
1654	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1655	  The kernel will offer these regions to the 'pmem' driver so
1656	  they can be used for persistent storage.
1657
1658	  Say Y if unsure.
1659
1660config HIGHPTE
1661	bool "Allocate 3rd-level pagetables from highmem"
1662	depends on HIGHMEM
1663	help
1664	  The VM uses one page table entry for each page of physical memory.
1665	  For systems with a lot of RAM, this can be wasteful of precious
1666	  low memory.  Setting this option will put user-space page table
1667	  entries in high memory.
1668
1669config X86_CHECK_BIOS_CORRUPTION
1670	bool "Check for low memory corruption"
1671	help
1672	  Periodically check for memory corruption in low memory, which
1673	  is suspected to be caused by BIOS.  Even when enabled in the
1674	  configuration, it is disabled at runtime.  Enable it by
1675	  setting "memory_corruption_check=1" on the kernel command
1676	  line.  By default it scans the low 64k of memory every 60
1677	  seconds; see the memory_corruption_check_size and
1678	  memory_corruption_check_period parameters in
1679	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1680
1681	  When enabled with the default parameters, this option has
1682	  almost no overhead, as it reserves a relatively small amount
1683	  of memory and scans it infrequently.  It both detects corruption
1684	  and prevents it from affecting the running system.
1685
1686	  It is, however, intended as a diagnostic tool; if repeatable
1687	  BIOS-originated corruption always affects the same memory,
1688	  you can use memmap= to prevent the kernel from using that
1689	  memory.
1690
1691config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1692	bool "Set the default setting of memory_corruption_check"
1693	depends on X86_CHECK_BIOS_CORRUPTION
1694	default y
1695	help
1696	  Set whether the default state of memory_corruption_check is
1697	  on or off.
1698
1699config MATH_EMULATION
1700	bool
1701	depends on MODIFY_LDT_SYSCALL
1702	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1703	help
1704	  Linux can emulate a math coprocessor (used for floating point
1705	  operations) if you don't have one. 486DX and Pentium processors have
1706	  a math coprocessor built in, 486SX and 386 do not, unless you added
1707	  a 487DX or 387, respectively. (The messages during boot time can
1708	  give you some hints here ["man dmesg"].) Everyone needs either a
1709	  coprocessor or this emulation.
1710
1711	  If you don't have a math coprocessor, you need to say Y here; if you
1712	  say Y here even though you have a coprocessor, the coprocessor will
1713	  be used nevertheless. (This behavior can be changed with the kernel
1714	  command line option "no387", which comes handy if your coprocessor
1715	  is broken. Try "man bootparam" or see the documentation of your boot
1716	  loader (lilo or loadlin) about how to pass options to the kernel at
1717	  boot time.) This means that it is a good idea to say Y here if you
1718	  intend to use this kernel on different machines.
1719
1720	  More information about the internals of the Linux math coprocessor
1721	  emulation can be found in <file:arch/x86/math-emu/README>.
1722
1723	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1724	  kernel, it won't hurt.
1725
1726config MTRR
1727	def_bool y
1728	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1729	help
1730	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1731	  the Memory Type Range Registers (MTRRs) may be used to control
1732	  processor access to memory ranges. This is most useful if you have
1733	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1734	  allows bus write transfers to be combined into a larger transfer
1735	  before bursting over the PCI/AGP bus. This can increase performance
1736	  of image write operations 2.5 times or more. Saying Y here creates a
1737	  /proc/mtrr file which may be used to manipulate your processor's
1738	  MTRRs. Typically the X server should use this.
1739
1740	  This code has a reasonably generic interface so that similar
1741	  control registers on other processors can be easily supported
1742	  as well:
1743
1744	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1745	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1746	  these, the ARRs are used to emulate the MTRRs.
1747	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1748	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1749	  write-combining. All of these processors are supported by this code
1750	  and it makes sense to say Y here if you have one of them.
1751
1752	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1753	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1754	  can lead to all sorts of problems, so it's good to say Y here.
1755
1756	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1757	  just add about 9 KB to your kernel.
1758
1759	  See <file:Documentation/x86/mtrr.rst> for more information.
1760
1761config MTRR_SANITIZER
1762	def_bool y
1763	prompt "MTRR cleanup support"
1764	depends on MTRR
1765	help
1766	  Convert MTRR layout from continuous to discrete, so X drivers can
1767	  add writeback entries.
1768
1769	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1770	  The largest mtrr entry size for a continuous block can be set with
1771	  mtrr_chunk_size.
1772
1773	  If unsure, say Y.
1774
1775config MTRR_SANITIZER_ENABLE_DEFAULT
1776	int "MTRR cleanup enable value (0-1)"
1777	range 0 1
1778	default "0"
1779	depends on MTRR_SANITIZER
1780	help
1781	  Enable mtrr cleanup default value
1782
1783config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1784	int "MTRR cleanup spare reg num (0-7)"
1785	range 0 7
1786	default "1"
1787	depends on MTRR_SANITIZER
1788	help
1789	  mtrr cleanup spare entries default, it can be changed via
1790	  mtrr_spare_reg_nr=N on the kernel command line.
1791
1792config X86_PAT
1793	def_bool y
1794	prompt "x86 PAT support" if EXPERT
1795	depends on MTRR
1796	help
1797	  Use PAT attributes to setup page level cache control.
1798
1799	  PATs are the modern equivalents of MTRRs and are much more
1800	  flexible than MTRRs.
1801
1802	  Say N here if you see bootup problems (boot crash, boot hang,
1803	  spontaneous reboots) or a non-working video driver.
1804
1805	  If unsure, say Y.
1806
1807config ARCH_USES_PG_UNCACHED
1808	def_bool y
1809	depends on X86_PAT
1810
1811config ARCH_RANDOM
1812	def_bool y
1813	prompt "x86 architectural random number generator" if EXPERT
1814	help
1815	  Enable the x86 architectural RDRAND instruction
1816	  (Intel Bull Mountain technology) to generate random numbers.
1817	  If supported, this is a high bandwidth, cryptographically
1818	  secure hardware random number generator.
1819
1820config X86_SMAP
1821	def_bool y
1822	prompt "Supervisor Mode Access Prevention" if EXPERT
1823	help
1824	  Supervisor Mode Access Prevention (SMAP) is a security
1825	  feature in newer Intel processors.  There is a small
1826	  performance cost if this enabled and turned on; there is
1827	  also a small increase in the kernel size if this is enabled.
1828
1829	  If unsure, say Y.
1830
1831config X86_UMIP
1832	def_bool y
1833	prompt "User Mode Instruction Prevention" if EXPERT
1834	help
1835	  User Mode Instruction Prevention (UMIP) is a security feature in
1836	  some x86 processors. If enabled, a general protection fault is
1837	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1838	  executed in user mode. These instructions unnecessarily expose
1839	  information about the hardware state.
1840
1841	  The vast majority of applications do not use these instructions.
1842	  For the very few that do, software emulation is provided in
1843	  specific cases in protected and virtual-8086 modes. Emulated
1844	  results are dummy.
1845
1846config CC_HAS_IBT
1847	# GCC >= 9 and binutils >= 2.29
1848	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1849	# Clang/LLVM >= 14
1850	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1851	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1852	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1853		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1854		  $(as-instr,endbr64)
1855
1856config X86_KERNEL_IBT
1857	prompt "Indirect Branch Tracking"
1858	bool
1859	depends on X86_64 && CC_HAS_IBT && STACK_VALIDATION
1860	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1861	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1862	help
1863	  Build the kernel with support for Indirect Branch Tracking, a
1864	  hardware support course-grain forward-edge Control Flow Integrity
1865	  protection. It enforces that all indirect calls must land on
1866	  an ENDBR instruction, as such, the compiler will instrument the
1867	  code with them to make this happen.
1868
1869	  In addition to building the kernel with IBT, seal all functions that
1870	  are not indirect call targets, avoiding them ever becomming one.
1871
1872	  This requires LTO like objtool runs and will slow down the build. It
1873	  does significantly reduce the number of ENDBR instructions in the
1874	  kernel image.
1875
1876config X86_INTEL_MEMORY_PROTECTION_KEYS
1877	prompt "Memory Protection Keys"
1878	def_bool y
1879	# Note: only available in 64-bit mode
1880	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1881	select ARCH_USES_HIGH_VMA_FLAGS
1882	select ARCH_HAS_PKEYS
1883	help
1884	  Memory Protection Keys provides a mechanism for enforcing
1885	  page-based protections, but without requiring modification of the
1886	  page tables when an application changes protection domains.
1887
1888	  For details, see Documentation/core-api/protection-keys.rst
1889
1890	  If unsure, say y.
1891
1892choice
1893	prompt "TSX enable mode"
1894	depends on CPU_SUP_INTEL
1895	default X86_INTEL_TSX_MODE_OFF
1896	help
1897	  Intel's TSX (Transactional Synchronization Extensions) feature
1898	  allows to optimize locking protocols through lock elision which
1899	  can lead to a noticeable performance boost.
1900
1901	  On the other hand it has been shown that TSX can be exploited
1902	  to form side channel attacks (e.g. TAA) and chances are there
1903	  will be more of those attacks discovered in the future.
1904
1905	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1906	  might override this decision by tsx=on the command line parameter.
1907	  Even with TSX enabled, the kernel will attempt to enable the best
1908	  possible TAA mitigation setting depending on the microcode available
1909	  for the particular machine.
1910
1911	  This option allows to set the default tsx mode between tsx=on, =off
1912	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1913	  details.
1914
1915	  Say off if not sure, auto if TSX is in use but it should be used on safe
1916	  platforms or on if TSX is in use and the security aspect of tsx is not
1917	  relevant.
1918
1919config X86_INTEL_TSX_MODE_OFF
1920	bool "off"
1921	help
1922	  TSX is disabled if possible - equals to tsx=off command line parameter.
1923
1924config X86_INTEL_TSX_MODE_ON
1925	bool "on"
1926	help
1927	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1928	  line parameter.
1929
1930config X86_INTEL_TSX_MODE_AUTO
1931	bool "auto"
1932	help
1933	  TSX is enabled on TSX capable HW that is believed to be safe against
1934	  side channel attacks- equals the tsx=auto command line parameter.
1935endchoice
1936
1937config X86_SGX
1938	bool "Software Guard eXtensions (SGX)"
1939	depends on X86_64 && CPU_SUP_INTEL
1940	depends on CRYPTO=y
1941	depends on CRYPTO_SHA256=y
1942	select SRCU
1943	select MMU_NOTIFIER
1944	select NUMA_KEEP_MEMINFO if NUMA
1945	select XARRAY_MULTI
1946	help
1947	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1948	  that can be used by applications to set aside private regions of code
1949	  and data, referred to as enclaves. An enclave's private memory can
1950	  only be accessed by code running within the enclave. Accesses from
1951	  outside the enclave, including other enclaves, are disallowed by
1952	  hardware.
1953
1954	  If unsure, say N.
1955
1956config EFI
1957	bool "EFI runtime service support"
1958	depends on ACPI
1959	select UCS2_STRING
1960	select EFI_RUNTIME_WRAPPERS
1961	select ARCH_USE_MEMREMAP_PROT
1962	help
1963	  This enables the kernel to use EFI runtime services that are
1964	  available (such as the EFI variable services).
1965
1966	  This option is only useful on systems that have EFI firmware.
1967	  In addition, you should use the latest ELILO loader available
1968	  at <http://elilo.sourceforge.net> in order to take advantage
1969	  of EFI runtime services. However, even with this option, the
1970	  resultant kernel should continue to boot on existing non-EFI
1971	  platforms.
1972
1973config EFI_STUB
1974	bool "EFI stub support"
1975	depends on EFI
1976	depends on $(cc-option,-mabi=ms) || X86_32
1977	select RELOCATABLE
1978	help
1979	  This kernel feature allows a bzImage to be loaded directly
1980	  by EFI firmware without the use of a bootloader.
1981
1982	  See Documentation/admin-guide/efi-stub.rst for more information.
1983
1984config EFI_MIXED
1985	bool "EFI mixed-mode support"
1986	depends on EFI_STUB && X86_64
1987	help
1988	   Enabling this feature allows a 64-bit kernel to be booted
1989	   on a 32-bit firmware, provided that your CPU supports 64-bit
1990	   mode.
1991
1992	   Note that it is not possible to boot a mixed-mode enabled
1993	   kernel via the EFI boot stub - a bootloader that supports
1994	   the EFI handover protocol must be used.
1995
1996	   If unsure, say N.
1997
1998source "kernel/Kconfig.hz"
1999
2000config KEXEC
2001	bool "kexec system call"
2002	select KEXEC_CORE
2003	help
2004	  kexec is a system call that implements the ability to shutdown your
2005	  current kernel, and to start another kernel.  It is like a reboot
2006	  but it is independent of the system firmware.   And like a reboot
2007	  you can start any kernel with it, not just Linux.
2008
2009	  The name comes from the similarity to the exec system call.
2010
2011	  It is an ongoing process to be certain the hardware in a machine
2012	  is properly shutdown, so do not be surprised if this code does not
2013	  initially work for you.  As of this writing the exact hardware
2014	  interface is strongly in flux, so no good recommendation can be
2015	  made.
2016
2017config KEXEC_FILE
2018	bool "kexec file based system call"
2019	select KEXEC_CORE
2020	select BUILD_BIN2C
2021	depends on X86_64
2022	depends on CRYPTO=y
2023	depends on CRYPTO_SHA256=y
2024	help
2025	  This is new version of kexec system call. This system call is
2026	  file based and takes file descriptors as system call argument
2027	  for kernel and initramfs as opposed to list of segments as
2028	  accepted by previous system call.
2029
2030config ARCH_HAS_KEXEC_PURGATORY
2031	def_bool KEXEC_FILE
2032
2033config KEXEC_SIG
2034	bool "Verify kernel signature during kexec_file_load() syscall"
2035	depends on KEXEC_FILE
2036	help
2037
2038	  This option makes the kexec_file_load() syscall check for a valid
2039	  signature of the kernel image.  The image can still be loaded without
2040	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2041	  there's a signature that we can check, then it must be valid.
2042
2043	  In addition to this option, you need to enable signature
2044	  verification for the corresponding kernel image type being
2045	  loaded in order for this to work.
2046
2047config KEXEC_SIG_FORCE
2048	bool "Require a valid signature in kexec_file_load() syscall"
2049	depends on KEXEC_SIG
2050	help
2051	  This option makes kernel signature verification mandatory for
2052	  the kexec_file_load() syscall.
2053
2054config KEXEC_BZIMAGE_VERIFY_SIG
2055	bool "Enable bzImage signature verification support"
2056	depends on KEXEC_SIG
2057	depends on SIGNED_PE_FILE_VERIFICATION
2058	select SYSTEM_TRUSTED_KEYRING
2059	help
2060	  Enable bzImage signature verification support.
2061
2062config CRASH_DUMP
2063	bool "kernel crash dumps"
2064	depends on X86_64 || (X86_32 && HIGHMEM)
2065	help
2066	  Generate crash dump after being started by kexec.
2067	  This should be normally only set in special crash dump kernels
2068	  which are loaded in the main kernel with kexec-tools into
2069	  a specially reserved region and then later executed after
2070	  a crash by kdump/kexec. The crash dump kernel must be compiled
2071	  to a memory address not used by the main kernel or BIOS using
2072	  PHYSICAL_START, or it must be built as a relocatable image
2073	  (CONFIG_RELOCATABLE=y).
2074	  For more details see Documentation/admin-guide/kdump/kdump.rst
2075
2076config KEXEC_JUMP
2077	bool "kexec jump"
2078	depends on KEXEC && HIBERNATION
2079	help
2080	  Jump between original kernel and kexeced kernel and invoke
2081	  code in physical address mode via KEXEC
2082
2083config PHYSICAL_START
2084	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2085	default "0x1000000"
2086	help
2087	  This gives the physical address where the kernel is loaded.
2088
2089	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2090	  bzImage will decompress itself to above physical address and
2091	  run from there. Otherwise, bzImage will run from the address where
2092	  it has been loaded by the boot loader and will ignore above physical
2093	  address.
2094
2095	  In normal kdump cases one does not have to set/change this option
2096	  as now bzImage can be compiled as a completely relocatable image
2097	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2098	  address. This option is mainly useful for the folks who don't want
2099	  to use a bzImage for capturing the crash dump and want to use a
2100	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2101	  to be specifically compiled to run from a specific memory area
2102	  (normally a reserved region) and this option comes handy.
2103
2104	  So if you are using bzImage for capturing the crash dump,
2105	  leave the value here unchanged to 0x1000000 and set
2106	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2107	  for capturing the crash dump change this value to start of
2108	  the reserved region.  In other words, it can be set based on
2109	  the "X" value as specified in the "crashkernel=YM@XM"
2110	  command line boot parameter passed to the panic-ed
2111	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2112	  for more details about crash dumps.
2113
2114	  Usage of bzImage for capturing the crash dump is recommended as
2115	  one does not have to build two kernels. Same kernel can be used
2116	  as production kernel and capture kernel. Above option should have
2117	  gone away after relocatable bzImage support is introduced. But it
2118	  is present because there are users out there who continue to use
2119	  vmlinux for dump capture. This option should go away down the
2120	  line.
2121
2122	  Don't change this unless you know what you are doing.
2123
2124config RELOCATABLE
2125	bool "Build a relocatable kernel"
2126	default y
2127	help
2128	  This builds a kernel image that retains relocation information
2129	  so it can be loaded someplace besides the default 1MB.
2130	  The relocations tend to make the kernel binary about 10% larger,
2131	  but are discarded at runtime.
2132
2133	  One use is for the kexec on panic case where the recovery kernel
2134	  must live at a different physical address than the primary
2135	  kernel.
2136
2137	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2138	  it has been loaded at and the compile time physical address
2139	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2140
2141config RANDOMIZE_BASE
2142	bool "Randomize the address of the kernel image (KASLR)"
2143	depends on RELOCATABLE
2144	default y
2145	help
2146	  In support of Kernel Address Space Layout Randomization (KASLR),
2147	  this randomizes the physical address at which the kernel image
2148	  is decompressed and the virtual address where the kernel
2149	  image is mapped, as a security feature that deters exploit
2150	  attempts relying on knowledge of the location of kernel
2151	  code internals.
2152
2153	  On 64-bit, the kernel physical and virtual addresses are
2154	  randomized separately. The physical address will be anywhere
2155	  between 16MB and the top of physical memory (up to 64TB). The
2156	  virtual address will be randomized from 16MB up to 1GB (9 bits
2157	  of entropy). Note that this also reduces the memory space
2158	  available to kernel modules from 1.5GB to 1GB.
2159
2160	  On 32-bit, the kernel physical and virtual addresses are
2161	  randomized together. They will be randomized from 16MB up to
2162	  512MB (8 bits of entropy).
2163
2164	  Entropy is generated using the RDRAND instruction if it is
2165	  supported. If RDTSC is supported, its value is mixed into
2166	  the entropy pool as well. If neither RDRAND nor RDTSC are
2167	  supported, then entropy is read from the i8254 timer. The
2168	  usable entropy is limited by the kernel being built using
2169	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2170	  minimum of 2MB. As a result, only 10 bits of entropy are
2171	  theoretically possible, but the implementations are further
2172	  limited due to memory layouts.
2173
2174	  If unsure, say Y.
2175
2176# Relocation on x86 needs some additional build support
2177config X86_NEED_RELOCS
2178	def_bool y
2179	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2180
2181config PHYSICAL_ALIGN
2182	hex "Alignment value to which kernel should be aligned"
2183	default "0x200000"
2184	range 0x2000 0x1000000 if X86_32
2185	range 0x200000 0x1000000 if X86_64
2186	help
2187	  This value puts the alignment restrictions on physical address
2188	  where kernel is loaded and run from. Kernel is compiled for an
2189	  address which meets above alignment restriction.
2190
2191	  If bootloader loads the kernel at a non-aligned address and
2192	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2193	  address aligned to above value and run from there.
2194
2195	  If bootloader loads the kernel at a non-aligned address and
2196	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2197	  load address and decompress itself to the address it has been
2198	  compiled for and run from there. The address for which kernel is
2199	  compiled already meets above alignment restrictions. Hence the
2200	  end result is that kernel runs from a physical address meeting
2201	  above alignment restrictions.
2202
2203	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2204	  this value must be a multiple of 0x200000.
2205
2206	  Don't change this unless you know what you are doing.
2207
2208config DYNAMIC_MEMORY_LAYOUT
2209	bool
2210	help
2211	  This option makes base addresses of vmalloc and vmemmap as well as
2212	  __PAGE_OFFSET movable during boot.
2213
2214config RANDOMIZE_MEMORY
2215	bool "Randomize the kernel memory sections"
2216	depends on X86_64
2217	depends on RANDOMIZE_BASE
2218	select DYNAMIC_MEMORY_LAYOUT
2219	default RANDOMIZE_BASE
2220	help
2221	   Randomizes the base virtual address of kernel memory sections
2222	   (physical memory mapping, vmalloc & vmemmap). This security feature
2223	   makes exploits relying on predictable memory locations less reliable.
2224
2225	   The order of allocations remains unchanged. Entropy is generated in
2226	   the same way as RANDOMIZE_BASE. Current implementation in the optimal
2227	   configuration have in average 30,000 different possible virtual
2228	   addresses for each memory section.
2229
2230	   If unsure, say Y.
2231
2232config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2233	hex "Physical memory mapping padding" if EXPERT
2234	depends on RANDOMIZE_MEMORY
2235	default "0xa" if MEMORY_HOTPLUG
2236	default "0x0"
2237	range 0x1 0x40 if MEMORY_HOTPLUG
2238	range 0x0 0x40
2239	help
2240	   Define the padding in terabytes added to the existing physical
2241	   memory size during kernel memory randomization. It is useful
2242	   for memory hotplug support but reduces the entropy available for
2243	   address randomization.
2244
2245	   If unsure, leave at the default value.
2246
2247config HOTPLUG_CPU
2248	def_bool y
2249	depends on SMP
2250
2251config BOOTPARAM_HOTPLUG_CPU0
2252	bool "Set default setting of cpu0_hotpluggable"
2253	depends on HOTPLUG_CPU
2254	help
2255	  Set whether default state of cpu0_hotpluggable is on or off.
2256
2257	  Say Y here to enable CPU0 hotplug by default. If this switch
2258	  is turned on, there is no need to give cpu0_hotplug kernel
2259	  parameter and the CPU0 hotplug feature is enabled by default.
2260
2261	  Please note: there are two known CPU0 dependencies if you want
2262	  to enable the CPU0 hotplug feature either by this switch or by
2263	  cpu0_hotplug kernel parameter.
2264
2265	  First, resume from hibernate or suspend always starts from CPU0.
2266	  So hibernate and suspend are prevented if CPU0 is offline.
2267
2268	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2269	  offline if any interrupt can not migrate out of CPU0. There may
2270	  be other CPU0 dependencies.
2271
2272	  Please make sure the dependencies are under your control before
2273	  you enable this feature.
2274
2275	  Say N if you don't want to enable CPU0 hotplug feature by default.
2276	  You still can enable the CPU0 hotplug feature at boot by kernel
2277	  parameter cpu0_hotplug.
2278
2279config DEBUG_HOTPLUG_CPU0
2280	def_bool n
2281	prompt "Debug CPU0 hotplug"
2282	depends on HOTPLUG_CPU
2283	help
2284	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2285	  soon as possible and boots up userspace with CPU0 offlined. User
2286	  can online CPU0 back after boot time.
2287
2288	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2289	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2290	  compilation or giving cpu0_hotplug kernel parameter at boot.
2291
2292	  If unsure, say N.
2293
2294config COMPAT_VDSO
2295	def_bool n
2296	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2297	depends on COMPAT_32
2298	help
2299	  Certain buggy versions of glibc will crash if they are
2300	  presented with a 32-bit vDSO that is not mapped at the address
2301	  indicated in its segment table.
2302
2303	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2304	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2305	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2306	  the only released version with the bug, but OpenSUSE 9
2307	  contains a buggy "glibc 2.3.2".
2308
2309	  The symptom of the bug is that everything crashes on startup, saying:
2310	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2311
2312	  Saying Y here changes the default value of the vdso32 boot
2313	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2314	  This works around the glibc bug but hurts performance.
2315
2316	  If unsure, say N: if you are compiling your own kernel, you
2317	  are unlikely to be using a buggy version of glibc.
2318
2319choice
2320	prompt "vsyscall table for legacy applications"
2321	depends on X86_64
2322	default LEGACY_VSYSCALL_XONLY
2323	help
2324	  Legacy user code that does not know how to find the vDSO expects
2325	  to be able to issue three syscalls by calling fixed addresses in
2326	  kernel space. Since this location is not randomized with ASLR,
2327	  it can be used to assist security vulnerability exploitation.
2328
2329	  This setting can be changed at boot time via the kernel command
2330	  line parameter vsyscall=[emulate|xonly|none].
2331
2332	  On a system with recent enough glibc (2.14 or newer) and no
2333	  static binaries, you can say None without a performance penalty
2334	  to improve security.
2335
2336	  If unsure, select "Emulate execution only".
2337
2338	config LEGACY_VSYSCALL_EMULATE
2339		bool "Full emulation"
2340		help
2341		  The kernel traps and emulates calls into the fixed vsyscall
2342		  address mapping. This makes the mapping non-executable, but
2343		  it still contains readable known contents, which could be
2344		  used in certain rare security vulnerability exploits. This
2345		  configuration is recommended when using legacy userspace
2346		  that still uses vsyscalls along with legacy binary
2347		  instrumentation tools that require code to be readable.
2348
2349		  An example of this type of legacy userspace is running
2350		  Pin on an old binary that still uses vsyscalls.
2351
2352	config LEGACY_VSYSCALL_XONLY
2353		bool "Emulate execution only"
2354		help
2355		  The kernel traps and emulates calls into the fixed vsyscall
2356		  address mapping and does not allow reads.  This
2357		  configuration is recommended when userspace might use the
2358		  legacy vsyscall area but support for legacy binary
2359		  instrumentation of legacy code is not needed.  It mitigates
2360		  certain uses of the vsyscall area as an ASLR-bypassing
2361		  buffer.
2362
2363	config LEGACY_VSYSCALL_NONE
2364		bool "None"
2365		help
2366		  There will be no vsyscall mapping at all. This will
2367		  eliminate any risk of ASLR bypass due to the vsyscall
2368		  fixed address mapping. Attempts to use the vsyscalls
2369		  will be reported to dmesg, so that either old or
2370		  malicious userspace programs can be identified.
2371
2372endchoice
2373
2374config CMDLINE_BOOL
2375	bool "Built-in kernel command line"
2376	help
2377	  Allow for specifying boot arguments to the kernel at
2378	  build time.  On some systems (e.g. embedded ones), it is
2379	  necessary or convenient to provide some or all of the
2380	  kernel boot arguments with the kernel itself (that is,
2381	  to not rely on the boot loader to provide them.)
2382
2383	  To compile command line arguments into the kernel,
2384	  set this option to 'Y', then fill in the
2385	  boot arguments in CONFIG_CMDLINE.
2386
2387	  Systems with fully functional boot loaders (i.e. non-embedded)
2388	  should leave this option set to 'N'.
2389
2390config CMDLINE
2391	string "Built-in kernel command string"
2392	depends on CMDLINE_BOOL
2393	default ""
2394	help
2395	  Enter arguments here that should be compiled into the kernel
2396	  image and used at boot time.  If the boot loader provides a
2397	  command line at boot time, it is appended to this string to
2398	  form the full kernel command line, when the system boots.
2399
2400	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2401	  change this behavior.
2402
2403	  In most cases, the command line (whether built-in or provided
2404	  by the boot loader) should specify the device for the root
2405	  file system.
2406
2407config CMDLINE_OVERRIDE
2408	bool "Built-in command line overrides boot loader arguments"
2409	depends on CMDLINE_BOOL && CMDLINE != ""
2410	help
2411	  Set this option to 'Y' to have the kernel ignore the boot loader
2412	  command line, and use ONLY the built-in command line.
2413
2414	  This is used to work around broken boot loaders.  This should
2415	  be set to 'N' under normal conditions.
2416
2417config MODIFY_LDT_SYSCALL
2418	bool "Enable the LDT (local descriptor table)" if EXPERT
2419	default y
2420	help
2421	  Linux can allow user programs to install a per-process x86
2422	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2423	  call.  This is required to run 16-bit or segmented code such as
2424	  DOSEMU or some Wine programs.  It is also used by some very old
2425	  threading libraries.
2426
2427	  Enabling this feature adds a small amount of overhead to
2428	  context switches and increases the low-level kernel attack
2429	  surface.  Disabling it removes the modify_ldt(2) system call.
2430
2431	  Saying 'N' here may make sense for embedded or server kernels.
2432
2433config STRICT_SIGALTSTACK_SIZE
2434	bool "Enforce strict size checking for sigaltstack"
2435	depends on DYNAMIC_SIGFRAME
2436	help
2437	  For historical reasons MINSIGSTKSZ is a constant which became
2438	  already too small with AVX512 support. Add a mechanism to
2439	  enforce strict checking of the sigaltstack size against the
2440	  real size of the FPU frame. This option enables the check
2441	  by default. It can also be controlled via the kernel command
2442	  line option 'strict_sas_size' independent of this config
2443	  switch. Enabling it might break existing applications which
2444	  allocate a too small sigaltstack but 'work' because they
2445	  never get a signal delivered.
2446
2447	  Say 'N' unless you want to really enforce this check.
2448
2449source "kernel/livepatch/Kconfig"
2450
2451endmenu
2452
2453config ARCH_HAS_ADD_PAGES
2454	def_bool y
2455	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2456
2457config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2458	def_bool y
2459
2460menu "Power management and ACPI options"
2461
2462config ARCH_HIBERNATION_HEADER
2463	def_bool y
2464	depends on HIBERNATION
2465
2466source "kernel/power/Kconfig"
2467
2468source "drivers/acpi/Kconfig"
2469
2470config X86_APM_BOOT
2471	def_bool y
2472	depends on APM
2473
2474menuconfig APM
2475	tristate "APM (Advanced Power Management) BIOS support"
2476	depends on X86_32 && PM_SLEEP
2477	help
2478	  APM is a BIOS specification for saving power using several different
2479	  techniques. This is mostly useful for battery powered laptops with
2480	  APM compliant BIOSes. If you say Y here, the system time will be
2481	  reset after a RESUME operation, the /proc/apm device will provide
2482	  battery status information, and user-space programs will receive
2483	  notification of APM "events" (e.g. battery status change).
2484
2485	  If you select "Y" here, you can disable actual use of the APM
2486	  BIOS by passing the "apm=off" option to the kernel at boot time.
2487
2488	  Note that the APM support is almost completely disabled for
2489	  machines with more than one CPU.
2490
2491	  In order to use APM, you will need supporting software. For location
2492	  and more information, read <file:Documentation/power/apm-acpi.rst>
2493	  and the Battery Powered Linux mini-HOWTO, available from
2494	  <http://www.tldp.org/docs.html#howto>.
2495
2496	  This driver does not spin down disk drives (see the hdparm(8)
2497	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2498	  VESA-compliant "green" monitors.
2499
2500	  This driver does not support the TI 4000M TravelMate and the ACER
2501	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2502	  desktop machines also don't have compliant BIOSes, and this driver
2503	  may cause those machines to panic during the boot phase.
2504
2505	  Generally, if you don't have a battery in your machine, there isn't
2506	  much point in using this driver and you should say N. If you get
2507	  random kernel OOPSes or reboots that don't seem to be related to
2508	  anything, try disabling/enabling this option (or disabling/enabling
2509	  APM in your BIOS).
2510
2511	  Some other things you should try when experiencing seemingly random,
2512	  "weird" problems:
2513
2514	  1) make sure that you have enough swap space and that it is
2515	  enabled.
2516	  2) pass the "no-hlt" option to the kernel
2517	  3) switch on floating point emulation in the kernel and pass
2518	  the "no387" option to the kernel
2519	  4) pass the "floppy=nodma" option to the kernel
2520	  5) pass the "mem=4M" option to the kernel (thereby disabling
2521	  all but the first 4 MB of RAM)
2522	  6) make sure that the CPU is not over clocked.
2523	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2524	  8) disable the cache from your BIOS settings
2525	  9) install a fan for the video card or exchange video RAM
2526	  10) install a better fan for the CPU
2527	  11) exchange RAM chips
2528	  12) exchange the motherboard.
2529
2530	  To compile this driver as a module, choose M here: the
2531	  module will be called apm.
2532
2533if APM
2534
2535config APM_IGNORE_USER_SUSPEND
2536	bool "Ignore USER SUSPEND"
2537	help
2538	  This option will ignore USER SUSPEND requests. On machines with a
2539	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2540	  series notebooks, it is necessary to say Y because of a BIOS bug.
2541
2542config APM_DO_ENABLE
2543	bool "Enable PM at boot time"
2544	help
2545	  Enable APM features at boot time. From page 36 of the APM BIOS
2546	  specification: "When disabled, the APM BIOS does not automatically
2547	  power manage devices, enter the Standby State, enter the Suspend
2548	  State, or take power saving steps in response to CPU Idle calls."
2549	  This driver will make CPU Idle calls when Linux is idle (unless this
2550	  feature is turned off -- see "Do CPU IDLE calls", below). This
2551	  should always save battery power, but more complicated APM features
2552	  will be dependent on your BIOS implementation. You may need to turn
2553	  this option off if your computer hangs at boot time when using APM
2554	  support, or if it beeps continuously instead of suspending. Turn
2555	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2556	  T400CDT. This is off by default since most machines do fine without
2557	  this feature.
2558
2559config APM_CPU_IDLE
2560	depends on CPU_IDLE
2561	bool "Make CPU Idle calls when idle"
2562	help
2563	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2564	  On some machines, this can activate improved power savings, such as
2565	  a slowed CPU clock rate, when the machine is idle. These idle calls
2566	  are made after the idle loop has run for some length of time (e.g.,
2567	  333 mS). On some machines, this will cause a hang at boot time or
2568	  whenever the CPU becomes idle. (On machines with more than one CPU,
2569	  this option does nothing.)
2570
2571config APM_DISPLAY_BLANK
2572	bool "Enable console blanking using APM"
2573	help
2574	  Enable console blanking using the APM. Some laptops can use this to
2575	  turn off the LCD backlight when the screen blanker of the Linux
2576	  virtual console blanks the screen. Note that this is only used by
2577	  the virtual console screen blanker, and won't turn off the backlight
2578	  when using the X Window system. This also doesn't have anything to
2579	  do with your VESA-compliant power-saving monitor. Further, this
2580	  option doesn't work for all laptops -- it might not turn off your
2581	  backlight at all, or it might print a lot of errors to the console,
2582	  especially if you are using gpm.
2583
2584config APM_ALLOW_INTS
2585	bool "Allow interrupts during APM BIOS calls"
2586	help
2587	  Normally we disable external interrupts while we are making calls to
2588	  the APM BIOS as a measure to lessen the effects of a badly behaving
2589	  BIOS implementation.  The BIOS should reenable interrupts if it
2590	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2591	  many of the newer IBM Thinkpads.  If you experience hangs when you
2592	  suspend, try setting this to Y.  Otherwise, say N.
2593
2594endif # APM
2595
2596source "drivers/cpufreq/Kconfig"
2597
2598source "drivers/cpuidle/Kconfig"
2599
2600source "drivers/idle/Kconfig"
2601
2602endmenu
2603
2604
2605menu "Bus options (PCI etc.)"
2606
2607choice
2608	prompt "PCI access mode"
2609	depends on X86_32 && PCI
2610	default PCI_GOANY
2611	help
2612	  On PCI systems, the BIOS can be used to detect the PCI devices and
2613	  determine their configuration. However, some old PCI motherboards
2614	  have BIOS bugs and may crash if this is done. Also, some embedded
2615	  PCI-based systems don't have any BIOS at all. Linux can also try to
2616	  detect the PCI hardware directly without using the BIOS.
2617
2618	  With this option, you can specify how Linux should detect the
2619	  PCI devices. If you choose "BIOS", the BIOS will be used,
2620	  if you choose "Direct", the BIOS won't be used, and if you
2621	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2622	  If you choose "Any", the kernel will try MMCONFIG, then the
2623	  direct access method and falls back to the BIOS if that doesn't
2624	  work. If unsure, go with the default, which is "Any".
2625
2626config PCI_GOBIOS
2627	bool "BIOS"
2628
2629config PCI_GOMMCONFIG
2630	bool "MMConfig"
2631
2632config PCI_GODIRECT
2633	bool "Direct"
2634
2635config PCI_GOOLPC
2636	bool "OLPC XO-1"
2637	depends on OLPC
2638
2639config PCI_GOANY
2640	bool "Any"
2641
2642endchoice
2643
2644config PCI_BIOS
2645	def_bool y
2646	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2647
2648# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2649config PCI_DIRECT
2650	def_bool y
2651	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2652
2653config PCI_MMCONFIG
2654	bool "Support mmconfig PCI config space access" if X86_64
2655	default y
2656	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2657	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2658
2659config PCI_OLPC
2660	def_bool y
2661	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2662
2663config PCI_XEN
2664	def_bool y
2665	depends on PCI && XEN
2666
2667config MMCONF_FAM10H
2668	def_bool y
2669	depends on X86_64 && PCI_MMCONFIG && ACPI
2670
2671config PCI_CNB20LE_QUIRK
2672	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2673	depends on PCI
2674	help
2675	  Read the PCI windows out of the CNB20LE host bridge. This allows
2676	  PCI hotplug to work on systems with the CNB20LE chipset which do
2677	  not have ACPI.
2678
2679	  There's no public spec for this chipset, and this functionality
2680	  is known to be incomplete.
2681
2682	  You should say N unless you know you need this.
2683
2684config ISA_BUS
2685	bool "ISA bus support on modern systems" if EXPERT
2686	help
2687	  Expose ISA bus device drivers and options available for selection and
2688	  configuration. Enable this option if your target machine has an ISA
2689	  bus. ISA is an older system, displaced by PCI and newer bus
2690	  architectures -- if your target machine is modern, it probably does
2691	  not have an ISA bus.
2692
2693	  If unsure, say N.
2694
2695# x86_64 have no ISA slots, but can have ISA-style DMA.
2696config ISA_DMA_API
2697	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2698	default y
2699	help
2700	  Enables ISA-style DMA support for devices requiring such controllers.
2701	  If unsure, say Y.
2702
2703if X86_32
2704
2705config ISA
2706	bool "ISA support"
2707	help
2708	  Find out whether you have ISA slots on your motherboard.  ISA is the
2709	  name of a bus system, i.e. the way the CPU talks to the other stuff
2710	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2711	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2712	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2713
2714config SCx200
2715	tristate "NatSemi SCx200 support"
2716	help
2717	  This provides basic support for National Semiconductor's
2718	  (now AMD's) Geode processors.  The driver probes for the
2719	  PCI-IDs of several on-chip devices, so its a good dependency
2720	  for other scx200_* drivers.
2721
2722	  If compiled as a module, the driver is named scx200.
2723
2724config SCx200HR_TIMER
2725	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2726	depends on SCx200
2727	default y
2728	help
2729	  This driver provides a clocksource built upon the on-chip
2730	  27MHz high-resolution timer.  Its also a workaround for
2731	  NSC Geode SC-1100's buggy TSC, which loses time when the
2732	  processor goes idle (as is done by the scheduler).  The
2733	  other workaround is idle=poll boot option.
2734
2735config OLPC
2736	bool "One Laptop Per Child support"
2737	depends on !X86_PAE
2738	select GPIOLIB
2739	select OF
2740	select OF_PROMTREE
2741	select IRQ_DOMAIN
2742	select OLPC_EC
2743	help
2744	  Add support for detecting the unique features of the OLPC
2745	  XO hardware.
2746
2747config OLPC_XO1_PM
2748	bool "OLPC XO-1 Power Management"
2749	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2750	help
2751	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2752
2753config OLPC_XO1_RTC
2754	bool "OLPC XO-1 Real Time Clock"
2755	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2756	help
2757	  Add support for the XO-1 real time clock, which can be used as a
2758	  programmable wakeup source.
2759
2760config OLPC_XO1_SCI
2761	bool "OLPC XO-1 SCI extras"
2762	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2763	depends on INPUT=y
2764	select POWER_SUPPLY
2765	help
2766	  Add support for SCI-based features of the OLPC XO-1 laptop:
2767	   - EC-driven system wakeups
2768	   - Power button
2769	   - Ebook switch
2770	   - Lid switch
2771	   - AC adapter status updates
2772	   - Battery status updates
2773
2774config OLPC_XO15_SCI
2775	bool "OLPC XO-1.5 SCI extras"
2776	depends on OLPC && ACPI
2777	select POWER_SUPPLY
2778	help
2779	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2780	   - EC-driven system wakeups
2781	   - AC adapter status updates
2782	   - Battery status updates
2783
2784config ALIX
2785	bool "PCEngines ALIX System Support (LED setup)"
2786	select GPIOLIB
2787	help
2788	  This option enables system support for the PCEngines ALIX.
2789	  At present this just sets up LEDs for GPIO control on
2790	  ALIX2/3/6 boards.  However, other system specific setup should
2791	  get added here.
2792
2793	  Note: You must still enable the drivers for GPIO and LED support
2794	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2795
2796	  Note: You have to set alix.force=1 for boards with Award BIOS.
2797
2798config NET5501
2799	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2800	select GPIOLIB
2801	help
2802	  This option enables system support for the Soekris Engineering net5501.
2803
2804config GEOS
2805	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2806	select GPIOLIB
2807	depends on DMI
2808	help
2809	  This option enables system support for the Traverse Technologies GEOS.
2810
2811config TS5500
2812	bool "Technologic Systems TS-5500 platform support"
2813	depends on MELAN
2814	select CHECK_SIGNATURE
2815	select NEW_LEDS
2816	select LEDS_CLASS
2817	help
2818	  This option enables system support for the Technologic Systems TS-5500.
2819
2820endif # X86_32
2821
2822config AMD_NB
2823	def_bool y
2824	depends on CPU_SUP_AMD && PCI
2825
2826endmenu
2827
2828
2829menu "Binary Emulations"
2830
2831config IA32_EMULATION
2832	bool "IA32 Emulation"
2833	depends on X86_64
2834	select ARCH_WANT_OLD_COMPAT_IPC
2835	select BINFMT_ELF
2836	select COMPAT_OLD_SIGACTION
2837	help
2838	  Include code to run legacy 32-bit programs under a
2839	  64-bit kernel. You should likely turn this on, unless you're
2840	  100% sure that you don't have any 32-bit programs left.
2841
2842config IA32_AOUT
2843	tristate "IA32 a.out support"
2844	depends on IA32_EMULATION
2845	depends on BROKEN
2846	help
2847	  Support old a.out binaries in the 32bit emulation.
2848
2849config X86_X32_ABI
2850	bool "x32 ABI for 64-bit mode"
2851	depends on X86_64
2852	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2853	# compressed debug sections to x86_x32 properly:
2854	# https://github.com/ClangBuiltLinux/linux/issues/514
2855	# https://github.com/ClangBuiltLinux/linux/issues/1141
2856	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2857	help
2858	  Include code to run binaries for the x32 native 32-bit ABI
2859	  for 64-bit processors.  An x32 process gets access to the
2860	  full 64-bit register file and wide data path while leaving
2861	  pointers at 32 bits for smaller memory footprint.
2862
2863config COMPAT_32
2864	def_bool y
2865	depends on IA32_EMULATION || X86_32
2866	select HAVE_UID16
2867	select OLD_SIGSUSPEND3
2868
2869config COMPAT
2870	def_bool y
2871	depends on IA32_EMULATION || X86_X32_ABI
2872
2873if COMPAT
2874config COMPAT_FOR_U64_ALIGNMENT
2875	def_bool y
2876
2877config SYSVIPC_COMPAT
2878	def_bool y
2879	depends on SYSVIPC
2880endif
2881
2882endmenu
2883
2884
2885config HAVE_ATOMIC_IOMAP
2886	def_bool y
2887	depends on X86_32
2888
2889source "arch/x86/kvm/Kconfig"
2890
2891source "arch/x86/Kconfig.assembler"
2892