xref: /openbmc/linux/arch/x86/Kconfig (revision 4627a000)
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_DEBUG_WX
98	select ARCH_HAS_ZONE_DMA_SET if EXPERT
99	select ARCH_HAVE_NMI_SAFE_CMPXCHG
100	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
101	select ARCH_MIGHT_HAVE_PC_PARPORT
102	select ARCH_MIGHT_HAVE_PC_SERIO
103	select ARCH_STACKWALK
104	select ARCH_SUPPORTS_ACPI
105	select ARCH_SUPPORTS_ATOMIC_RMW
106	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
107	select ARCH_SUPPORTS_PAGE_TABLE_CHECK	if X86_64
108	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
109	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
110	select ARCH_SUPPORTS_CFI_CLANG		if X86_64
111	select ARCH_USES_CFI_TRAPS		if X86_64 && CFI_CLANG
112	select ARCH_SUPPORTS_LTO_CLANG
113	select ARCH_SUPPORTS_LTO_CLANG_THIN
114	select ARCH_USE_BUILTIN_BSWAP
115	select ARCH_USE_MEMTEST
116	select ARCH_USE_QUEUED_RWLOCKS
117	select ARCH_USE_QUEUED_SPINLOCKS
118	select ARCH_USE_SYM_ANNOTATIONS
119	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
120	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64
121	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
122	select ARCH_WANTS_NO_INSTR
123	select ARCH_WANT_GENERAL_HUGETLB
124	select ARCH_WANT_HUGE_PMD_SHARE
125	select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP	if X86_64
126	select ARCH_WANT_LD_ORPHAN_WARN
127	select ARCH_WANTS_THP_SWAP		if X86_64
128	select ARCH_HAS_PARANOID_L1D_FLUSH
129	select BUILDTIME_TABLE_SORT
130	select CLKEVT_I8253
131	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
132	select CLOCKSOURCE_WATCHDOG
133	select DCACHE_WORD_ACCESS
134	select DYNAMIC_SIGFRAME
135	select EDAC_ATOMIC_SCRUB
136	select EDAC_SUPPORT
137	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
138	select GENERIC_CLOCKEVENTS_MIN_ADJUST
139	select GENERIC_CMOS_UPDATE
140	select GENERIC_CPU_AUTOPROBE
141	select GENERIC_CPU_VULNERABILITIES
142	select GENERIC_EARLY_IOREMAP
143	select GENERIC_ENTRY
144	select GENERIC_IOMAP
145	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
146	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
147	select GENERIC_IRQ_MIGRATION		if SMP
148	select GENERIC_IRQ_PROBE
149	select GENERIC_IRQ_RESERVATION_MODE
150	select GENERIC_IRQ_SHOW
151	select GENERIC_PENDING_IRQ		if SMP
152	select GENERIC_PTDUMP
153	select GENERIC_SMP_IDLE_THREAD
154	select GENERIC_TIME_VSYSCALL
155	select GENERIC_GETTIMEOFDAY
156	select GENERIC_VDSO_TIME_NS
157	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
158	select HARDIRQS_SW_RESEND
159	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
160	select HAVE_ACPI_APEI			if ACPI
161	select HAVE_ACPI_APEI_NMI		if ACPI
162	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
163	select HAVE_ARCH_AUDITSYSCALL
164	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
165	select HAVE_ARCH_HUGE_VMALLOC		if X86_64
166	select HAVE_ARCH_JUMP_LABEL
167	select HAVE_ARCH_JUMP_LABEL_RELATIVE
168	select HAVE_ARCH_KASAN			if X86_64
169	select HAVE_ARCH_KASAN_VMALLOC		if X86_64
170	select HAVE_ARCH_KFENCE
171	select HAVE_ARCH_KGDB
172	select HAVE_ARCH_MMAP_RND_BITS		if MMU
173	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
174	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
175	select HAVE_ARCH_PREL32_RELOCATIONS
176	select HAVE_ARCH_SECCOMP_FILTER
177	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
178	select HAVE_ARCH_STACKLEAK
179	select HAVE_ARCH_TRACEHOOK
180	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
181	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
182	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
183	select HAVE_ARCH_USERFAULTFD_MINOR	if X86_64 && USERFAULTFD
184	select HAVE_ARCH_VMAP_STACK		if X86_64
185	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
186	select HAVE_ARCH_WITHIN_STACK_FRAMES
187	select HAVE_ASM_MODVERSIONS
188	select HAVE_CMPXCHG_DOUBLE
189	select HAVE_CMPXCHG_LOCAL
190	select HAVE_CONTEXT_TRACKING_USER		if X86_64
191	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
192	select HAVE_C_RECORDMCOUNT
193	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
194	select HAVE_BUILDTIME_MCOUNT_SORT
195	select HAVE_DEBUG_KMEMLEAK
196	select HAVE_DMA_CONTIGUOUS
197	select HAVE_DYNAMIC_FTRACE
198	select HAVE_DYNAMIC_FTRACE_WITH_REGS
199	select HAVE_DYNAMIC_FTRACE_WITH_ARGS	if X86_64
200	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
201	select HAVE_SAMPLE_FTRACE_DIRECT	if X86_64
202	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
203	select HAVE_EBPF_JIT
204	select HAVE_EFFICIENT_UNALIGNED_ACCESS
205	select HAVE_EISA
206	select HAVE_EXIT_THREAD
207	select HAVE_FAST_GUP
208	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
209	select HAVE_FTRACE_MCOUNT_RECORD
210	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
211	select HAVE_FUNCTION_TRACER
212	select HAVE_GCC_PLUGINS
213	select HAVE_HW_BREAKPOINT
214	select HAVE_IOREMAP_PROT
215	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
216	select HAVE_IRQ_TIME_ACCOUNTING
217	select HAVE_JUMP_LABEL_HACK		if HAVE_OBJTOOL
218	select HAVE_KERNEL_BZIP2
219	select HAVE_KERNEL_GZIP
220	select HAVE_KERNEL_LZ4
221	select HAVE_KERNEL_LZMA
222	select HAVE_KERNEL_LZO
223	select HAVE_KERNEL_XZ
224	select HAVE_KERNEL_ZSTD
225	select HAVE_KPROBES
226	select HAVE_KPROBES_ON_FTRACE
227	select HAVE_FUNCTION_ERROR_INJECTION
228	select HAVE_KRETPROBES
229	select HAVE_RETHOOK
230	select HAVE_KVM
231	select HAVE_LIVEPATCH			if X86_64
232	select HAVE_MIXED_BREAKPOINTS_REGS
233	select HAVE_MOD_ARCH_SPECIFIC
234	select HAVE_MOVE_PMD
235	select HAVE_MOVE_PUD
236	select HAVE_NOINSTR_HACK		if HAVE_OBJTOOL
237	select HAVE_NMI
238	select HAVE_NOINSTR_VALIDATION		if HAVE_OBJTOOL
239	select HAVE_OBJTOOL			if X86_64
240	select HAVE_OPTPROBES
241	select HAVE_PCSPKR_PLATFORM
242	select HAVE_PERF_EVENTS
243	select HAVE_PERF_EVENTS_NMI
244	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
245	select HAVE_PCI
246	select HAVE_PERF_REGS
247	select HAVE_PERF_USER_STACK_DUMP
248	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
249	select MMU_GATHER_MERGE_VMAS
250	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
251	select HAVE_REGS_AND_STACK_ACCESS_API
252	select HAVE_RELIABLE_STACKTRACE		if UNWINDER_ORC || STACK_VALIDATION
253	select HAVE_FUNCTION_ARG_ACCESS_API
254	select HAVE_SETUP_PER_CPU_AREA
255	select HAVE_SOFTIRQ_ON_OWN_STACK
256	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
257	select HAVE_STACK_VALIDATION		if HAVE_OBJTOOL
258	select HAVE_STATIC_CALL
259	select HAVE_STATIC_CALL_INLINE		if HAVE_OBJTOOL
260	select HAVE_PREEMPT_DYNAMIC_CALL
261	select HAVE_RSEQ
262	select HAVE_RUST			if X86_64
263	select HAVE_SYSCALL_TRACEPOINTS
264	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
265	select HAVE_UNSTABLE_SCHED_CLOCK
266	select HAVE_USER_RETURN_NOTIFIER
267	select HAVE_GENERIC_VDSO
268	select HOTPLUG_SMT			if SMP
269	select IRQ_FORCED_THREADING
270	select NEED_PER_CPU_EMBED_FIRST_CHUNK
271	select NEED_PER_CPU_PAGE_FIRST_CHUNK
272	select NEED_SG_DMA_LENGTH
273	select PCI_DOMAINS			if PCI
274	select PCI_LOCKLESS_CONFIG		if PCI
275	select PERF_EVENTS
276	select RTC_LIB
277	select RTC_MC146818_LIB
278	select SPARSE_IRQ
279	select SRCU
280	select SYSCTL_EXCEPTION_TRACE
281	select THREAD_INFO_IN_TASK
282	select TRACE_IRQFLAGS_SUPPORT
283	select TRACE_IRQFLAGS_NMI_SUPPORT
284	select USER_STACKTRACE_SUPPORT
285	select HAVE_ARCH_KCSAN			if X86_64
286	select X86_FEATURE_NAMES		if PROC_FS
287	select PROC_PID_ARCH_STATUS		if PROC_FS
288	select HAVE_ARCH_NODE_DEV_GROUP		if X86_SGX
289	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
290
291config INSTRUCTION_DECODER
292	def_bool y
293	depends on KPROBES || PERF_EVENTS || UPROBES
294
295config OUTPUT_FORMAT
296	string
297	default "elf32-i386" if X86_32
298	default "elf64-x86-64" if X86_64
299
300config LOCKDEP_SUPPORT
301	def_bool y
302
303config STACKTRACE_SUPPORT
304	def_bool y
305
306config MMU
307	def_bool y
308
309config ARCH_MMAP_RND_BITS_MIN
310	default 28 if 64BIT
311	default 8
312
313config ARCH_MMAP_RND_BITS_MAX
314	default 32 if 64BIT
315	default 16
316
317config ARCH_MMAP_RND_COMPAT_BITS_MIN
318	default 8
319
320config ARCH_MMAP_RND_COMPAT_BITS_MAX
321	default 16
322
323config SBUS
324	bool
325
326config GENERIC_ISA_DMA
327	def_bool y
328	depends on ISA_DMA_API
329
330config GENERIC_BUG
331	def_bool y
332	depends on BUG
333	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
334
335config GENERIC_BUG_RELATIVE_POINTERS
336	bool
337
338config ARCH_MAY_HAVE_PC_FDC
339	def_bool y
340	depends on ISA_DMA_API
341
342config GENERIC_CALIBRATE_DELAY
343	def_bool y
344
345config ARCH_HAS_CPU_RELAX
346	def_bool y
347
348config ARCH_HIBERNATION_POSSIBLE
349	def_bool y
350
351config ARCH_NR_GPIO
352	int
353	default 1024 if X86_64
354	default 512
355
356config ARCH_SUSPEND_POSSIBLE
357	def_bool y
358
359config AUDIT_ARCH
360	def_bool y if X86_64
361
362config KASAN_SHADOW_OFFSET
363	hex
364	depends on KASAN
365	default 0xdffffc0000000000
366
367config HAVE_INTEL_TXT
368	def_bool y
369	depends on INTEL_IOMMU && ACPI
370
371config X86_32_SMP
372	def_bool y
373	depends on X86_32 && SMP
374
375config X86_64_SMP
376	def_bool y
377	depends on X86_64 && SMP
378
379config ARCH_SUPPORTS_UPROBES
380	def_bool y
381
382config FIX_EARLYCON_MEM
383	def_bool y
384
385config DYNAMIC_PHYSICAL_MASK
386	bool
387
388config PGTABLE_LEVELS
389	int
390	default 5 if X86_5LEVEL
391	default 4 if X86_64
392	default 3 if X86_PAE
393	default 2
394
395config CC_HAS_SANE_STACKPROTECTOR
396	bool
397	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
398	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
399	help
400	  We have to make sure stack protector is unconditionally disabled if
401	  the compiler produces broken code or if it does not let us control
402	  the segment on 32-bit kernels.
403
404menu "Processor type and features"
405
406config SMP
407	bool "Symmetric multi-processing support"
408	help
409	  This enables support for systems with more than one CPU. If you have
410	  a system with only one CPU, say N. If you have a system with more
411	  than one CPU, say Y.
412
413	  If you say N here, the kernel will run on uni- and multiprocessor
414	  machines, but will use only one CPU of a multiprocessor machine. If
415	  you say Y here, the kernel will run on many, but not all,
416	  uniprocessor machines. On a uniprocessor machine, the kernel
417	  will run faster if you say N here.
418
419	  Note that if you say Y here and choose architecture "586" or
420	  "Pentium" under "Processor family", the kernel will not work on 486
421	  architectures. Similarly, multiprocessor kernels for the "PPro"
422	  architecture may not work on all Pentium based boards.
423
424	  People using multiprocessor machines who say Y here should also say
425	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
426	  Management" code will be disabled if you say Y here.
427
428	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
429	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
430	  <http://www.tldp.org/docs.html#howto>.
431
432	  If you don't know what to do here, say N.
433
434config X86_FEATURE_NAMES
435	bool "Processor feature human-readable names" if EMBEDDED
436	default y
437	help
438	  This option compiles in a table of x86 feature bits and corresponding
439	  names.  This is required to support /proc/cpuinfo and a few kernel
440	  messages.  You can disable this to save space, at the expense of
441	  making those few kernel messages show numeric feature bits instead.
442
443	  If in doubt, say Y.
444
445config X86_X2APIC
446	bool "Support x2apic"
447	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
448	help
449	  This enables x2apic support on CPUs that have this feature.
450
451	  This allows 32-bit apic IDs (so it can support very large systems),
452	  and accesses the local apic via MSRs not via mmio.
453
454	  If you don't know what to do here, say N.
455
456config X86_MPPARSE
457	bool "Enable MPS table" if ACPI
458	default y
459	depends on X86_LOCAL_APIC
460	help
461	  For old smp systems that do not have proper acpi support. Newer systems
462	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
463
464config GOLDFISH
465	def_bool y
466	depends on X86_GOLDFISH
467
468config X86_CPU_RESCTRL
469	bool "x86 CPU resource control support"
470	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
471	select KERNFS
472	select PROC_CPU_RESCTRL		if PROC_FS
473	help
474	  Enable x86 CPU resource control support.
475
476	  Provide support for the allocation and monitoring of system resources
477	  usage by the CPU.
478
479	  Intel calls this Intel Resource Director Technology
480	  (Intel(R) RDT). More information about RDT can be found in the
481	  Intel x86 Architecture Software Developer Manual.
482
483	  AMD calls this AMD Platform Quality of Service (AMD QoS).
484	  More information about AMD QoS can be found in the AMD64 Technology
485	  Platform Quality of Service Extensions manual.
486
487	  Say N if unsure.
488
489if X86_32
490config X86_BIGSMP
491	bool "Support for big SMP systems with more than 8 CPUs"
492	depends on SMP
493	help
494	  This option is needed for the systems that have more than 8 CPUs.
495
496config X86_EXTENDED_PLATFORM
497	bool "Support for extended (non-PC) x86 platforms"
498	default y
499	help
500	  If you disable this option then the kernel will only support
501	  standard PC platforms. (which covers the vast majority of
502	  systems out there.)
503
504	  If you enable this option then you'll be able to select support
505	  for the following (non-PC) 32 bit x86 platforms:
506		Goldfish (Android emulator)
507		AMD Elan
508		RDC R-321x SoC
509		SGI 320/540 (Visual Workstation)
510		STA2X11-based (e.g. Northville)
511		Moorestown MID devices
512
513	  If you have one of these systems, or if you want to build a
514	  generic distribution kernel, say Y here - otherwise say N.
515endif # X86_32
516
517if X86_64
518config X86_EXTENDED_PLATFORM
519	bool "Support for extended (non-PC) x86 platforms"
520	default y
521	help
522	  If you disable this option then the kernel will only support
523	  standard PC platforms. (which covers the vast majority of
524	  systems out there.)
525
526	  If you enable this option then you'll be able to select support
527	  for the following (non-PC) 64 bit x86 platforms:
528		Numascale NumaChip
529		ScaleMP vSMP
530		SGI Ultraviolet
531
532	  If you have one of these systems, or if you want to build a
533	  generic distribution kernel, say Y here - otherwise say N.
534endif # X86_64
535# This is an alphabetically sorted list of 64 bit extended platforms
536# Please maintain the alphabetic order if and when there are additions
537config X86_NUMACHIP
538	bool "Numascale NumaChip"
539	depends on X86_64
540	depends on X86_EXTENDED_PLATFORM
541	depends on NUMA
542	depends on SMP
543	depends on X86_X2APIC
544	depends on PCI_MMCONFIG
545	help
546	  Adds support for Numascale NumaChip large-SMP systems. Needed to
547	  enable more than ~168 cores.
548	  If you don't have one of these, you should say N here.
549
550config X86_VSMP
551	bool "ScaleMP vSMP"
552	select HYPERVISOR_GUEST
553	select PARAVIRT
554	depends on X86_64 && PCI
555	depends on X86_EXTENDED_PLATFORM
556	depends on SMP
557	help
558	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
559	  supposed to run on these EM64T-based machines.  Only choose this option
560	  if you have one of these machines.
561
562config X86_UV
563	bool "SGI Ultraviolet"
564	depends on X86_64
565	depends on X86_EXTENDED_PLATFORM
566	depends on NUMA
567	depends on EFI
568	depends on KEXEC_CORE
569	depends on X86_X2APIC
570	depends on PCI
571	help
572	  This option is needed in order to support SGI Ultraviolet systems.
573	  If you don't have one of these, you should say N here.
574
575# Following is an alphabetically sorted list of 32 bit extended platforms
576# Please maintain the alphabetic order if and when there are additions
577
578config X86_GOLDFISH
579	bool "Goldfish (Virtual Platform)"
580	depends on X86_EXTENDED_PLATFORM
581	help
582	  Enable support for the Goldfish virtual platform used primarily
583	  for Android development. Unless you are building for the Android
584	  Goldfish emulator say N here.
585
586config X86_INTEL_CE
587	bool "CE4100 TV platform"
588	depends on PCI
589	depends on PCI_GODIRECT
590	depends on X86_IO_APIC
591	depends on X86_32
592	depends on X86_EXTENDED_PLATFORM
593	select X86_REBOOTFIXUPS
594	select OF
595	select OF_EARLY_FLATTREE
596	help
597	  Select for the Intel CE media processor (CE4100) SOC.
598	  This option compiles in support for the CE4100 SOC for settop
599	  boxes and media devices.
600
601config X86_INTEL_MID
602	bool "Intel MID platform support"
603	depends on X86_EXTENDED_PLATFORM
604	depends on X86_PLATFORM_DEVICES
605	depends on PCI
606	depends on X86_64 || (PCI_GOANY && X86_32)
607	depends on X86_IO_APIC
608	select I2C
609	select DW_APB_TIMER
610	select INTEL_SCU_PCI
611	help
612	  Select to build a kernel capable of supporting Intel MID (Mobile
613	  Internet Device) platform systems which do not have the PCI legacy
614	  interfaces. If you are building for a PC class system say N here.
615
616	  Intel MID platforms are based on an Intel processor and chipset which
617	  consume less power than most of the x86 derivatives.
618
619config X86_INTEL_QUARK
620	bool "Intel Quark platform support"
621	depends on X86_32
622	depends on X86_EXTENDED_PLATFORM
623	depends on X86_PLATFORM_DEVICES
624	depends on X86_TSC
625	depends on PCI
626	depends on PCI_GOANY
627	depends on X86_IO_APIC
628	select IOSF_MBI
629	select INTEL_IMR
630	select COMMON_CLK
631	help
632	  Select to include support for Quark X1000 SoC.
633	  Say Y here if you have a Quark based system such as the Arduino
634	  compatible Intel Galileo.
635
636config X86_INTEL_LPSS
637	bool "Intel Low Power Subsystem Support"
638	depends on X86 && ACPI && PCI
639	select COMMON_CLK
640	select PINCTRL
641	select IOSF_MBI
642	help
643	  Select to build support for Intel Low Power Subsystem such as
644	  found on Intel Lynxpoint PCH. Selecting this option enables
645	  things like clock tree (common clock framework) and pincontrol
646	  which are needed by the LPSS peripheral drivers.
647
648config X86_AMD_PLATFORM_DEVICE
649	bool "AMD ACPI2Platform devices support"
650	depends on ACPI
651	select COMMON_CLK
652	select PINCTRL
653	help
654	  Select to interpret AMD specific ACPI device to platform device
655	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
656	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
657	  implemented under PINCTRL subsystem.
658
659config IOSF_MBI
660	tristate "Intel SoC IOSF Sideband support for SoC platforms"
661	depends on PCI
662	help
663	  This option enables sideband register access support for Intel SoC
664	  platforms. On these platforms the IOSF sideband is used in lieu of
665	  MSR's for some register accesses, mostly but not limited to thermal
666	  and power. Drivers may query the availability of this device to
667	  determine if they need the sideband in order to work on these
668	  platforms. The sideband is available on the following SoC products.
669	  This list is not meant to be exclusive.
670	   - BayTrail
671	   - Braswell
672	   - Quark
673
674	  You should say Y if you are running a kernel on one of these SoC's.
675
676config IOSF_MBI_DEBUG
677	bool "Enable IOSF sideband access through debugfs"
678	depends on IOSF_MBI && DEBUG_FS
679	help
680	  Select this option to expose the IOSF sideband access registers (MCR,
681	  MDR, MCRX) through debugfs to write and read register information from
682	  different units on the SoC. This is most useful for obtaining device
683	  state information for debug and analysis. As this is a general access
684	  mechanism, users of this option would have specific knowledge of the
685	  device they want to access.
686
687	  If you don't require the option or are in doubt, say N.
688
689config X86_RDC321X
690	bool "RDC R-321x SoC"
691	depends on X86_32
692	depends on X86_EXTENDED_PLATFORM
693	select M486
694	select X86_REBOOTFIXUPS
695	help
696	  This option is needed for RDC R-321x system-on-chip, also known
697	  as R-8610-(G).
698	  If you don't have one of these chips, you should say N here.
699
700config X86_32_NON_STANDARD
701	bool "Support non-standard 32-bit SMP architectures"
702	depends on X86_32 && SMP
703	depends on X86_EXTENDED_PLATFORM
704	help
705	  This option compiles in the bigsmp and STA2X11 default
706	  subarchitectures.  It is intended for a generic binary
707	  kernel. If you select them all, kernel will probe it one by
708	  one and will fallback to default.
709
710# Alphabetically sorted list of Non standard 32 bit platforms
711
712config X86_SUPPORTS_MEMORY_FAILURE
713	def_bool y
714	# MCE code calls memory_failure():
715	depends on X86_MCE
716	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
717	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
718	depends on X86_64 || !SPARSEMEM
719	select ARCH_SUPPORTS_MEMORY_FAILURE
720
721config STA2X11
722	bool "STA2X11 Companion Chip Support"
723	depends on X86_32_NON_STANDARD && PCI
724	select SWIOTLB
725	select MFD_STA2X11
726	select GPIOLIB
727	help
728	  This adds support for boards based on the STA2X11 IO-Hub,
729	  a.k.a. "ConneXt". The chip is used in place of the standard
730	  PC chipset, so all "standard" peripherals are missing. If this
731	  option is selected the kernel will still be able to boot on
732	  standard PC machines.
733
734config X86_32_IRIS
735	tristate "Eurobraille/Iris poweroff module"
736	depends on X86_32
737	help
738	  The Iris machines from EuroBraille do not have APM or ACPI support
739	  to shut themselves down properly.  A special I/O sequence is
740	  needed to do so, which is what this module does at
741	  kernel shutdown.
742
743	  This is only for Iris machines from EuroBraille.
744
745	  If unused, say N.
746
747config SCHED_OMIT_FRAME_POINTER
748	def_bool y
749	prompt "Single-depth WCHAN output"
750	depends on X86
751	help
752	  Calculate simpler /proc/<PID>/wchan values. If this option
753	  is disabled then wchan values will recurse back to the
754	  caller function. This provides more accurate wchan values,
755	  at the expense of slightly more scheduling overhead.
756
757	  If in doubt, say "Y".
758
759menuconfig HYPERVISOR_GUEST
760	bool "Linux guest support"
761	help
762	  Say Y here to enable options for running Linux under various hyper-
763	  visors. This option enables basic hypervisor detection and platform
764	  setup.
765
766	  If you say N, all options in this submenu will be skipped and
767	  disabled, and Linux guest support won't be built in.
768
769if HYPERVISOR_GUEST
770
771config PARAVIRT
772	bool "Enable paravirtualization code"
773	depends on HAVE_STATIC_CALL
774	help
775	  This changes the kernel so it can modify itself when it is run
776	  under a hypervisor, potentially improving performance significantly
777	  over full virtualization.  However, when run without a hypervisor
778	  the kernel is theoretically slower and slightly larger.
779
780config PARAVIRT_XXL
781	bool
782
783config PARAVIRT_DEBUG
784	bool "paravirt-ops debugging"
785	depends on PARAVIRT && DEBUG_KERNEL
786	help
787	  Enable to debug paravirt_ops internals.  Specifically, BUG if
788	  a paravirt_op is missing when it is called.
789
790config PARAVIRT_SPINLOCKS
791	bool "Paravirtualization layer for spinlocks"
792	depends on PARAVIRT && SMP
793	help
794	  Paravirtualized spinlocks allow a pvops backend to replace the
795	  spinlock implementation with something virtualization-friendly
796	  (for example, block the virtual CPU rather than spinning).
797
798	  It has a minimal impact on native kernels and gives a nice performance
799	  benefit on paravirtualized KVM / Xen kernels.
800
801	  If you are unsure how to answer this question, answer Y.
802
803config X86_HV_CALLBACK_VECTOR
804	def_bool n
805
806source "arch/x86/xen/Kconfig"
807
808config KVM_GUEST
809	bool "KVM Guest support (including kvmclock)"
810	depends on PARAVIRT
811	select PARAVIRT_CLOCK
812	select ARCH_CPUIDLE_HALTPOLL
813	select X86_HV_CALLBACK_VECTOR
814	default y
815	help
816	  This option enables various optimizations for running under the KVM
817	  hypervisor. It includes a paravirtualized clock, so that instead
818	  of relying on a PIT (or probably other) emulation by the
819	  underlying device model, the host provides the guest with
820	  timing infrastructure such as time of day, and system time
821
822config ARCH_CPUIDLE_HALTPOLL
823	def_bool n
824	prompt "Disable host haltpoll when loading haltpoll driver"
825	help
826	  If virtualized under KVM, disable host haltpoll.
827
828config PVH
829	bool "Support for running PVH guests"
830	help
831	  This option enables the PVH entry point for guest virtual machines
832	  as specified in the x86/HVM direct boot ABI.
833
834config PARAVIRT_TIME_ACCOUNTING
835	bool "Paravirtual steal time accounting"
836	depends on PARAVIRT
837	help
838	  Select this option to enable fine granularity task steal time
839	  accounting. Time spent executing other tasks in parallel with
840	  the current vCPU is discounted from the vCPU power. To account for
841	  that, there can be a small performance impact.
842
843	  If in doubt, say N here.
844
845config PARAVIRT_CLOCK
846	bool
847
848config JAILHOUSE_GUEST
849	bool "Jailhouse non-root cell support"
850	depends on X86_64 && PCI
851	select X86_PM_TIMER
852	help
853	  This option allows to run Linux as guest in a Jailhouse non-root
854	  cell. You can leave this option disabled if you only want to start
855	  Jailhouse and run Linux afterwards in the root cell.
856
857config ACRN_GUEST
858	bool "ACRN Guest support"
859	depends on X86_64
860	select X86_HV_CALLBACK_VECTOR
861	help
862	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
863	  a flexible, lightweight reference open-source hypervisor, built with
864	  real-time and safety-criticality in mind. It is built for embedded
865	  IOT with small footprint and real-time features. More details can be
866	  found in https://projectacrn.org/.
867
868config INTEL_TDX_GUEST
869	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
870	depends on X86_64 && CPU_SUP_INTEL
871	depends on X86_X2APIC
872	select ARCH_HAS_CC_PLATFORM
873	select X86_MEM_ENCRYPT
874	select X86_MCE
875	help
876	  Support running as a guest under Intel TDX.  Without this support,
877	  the guest kernel can not boot or run under TDX.
878	  TDX includes memory encryption and integrity capabilities
879	  which protect the confidentiality and integrity of guest
880	  memory contents and CPU state. TDX guests are protected from
881	  some attacks from the VMM.
882
883endif # HYPERVISOR_GUEST
884
885source "arch/x86/Kconfig.cpu"
886
887config HPET_TIMER
888	def_bool X86_64
889	prompt "HPET Timer Support" if X86_32
890	help
891	  Use the IA-PC HPET (High Precision Event Timer) to manage
892	  time in preference to the PIT and RTC, if a HPET is
893	  present.
894	  HPET is the next generation timer replacing legacy 8254s.
895	  The HPET provides a stable time base on SMP
896	  systems, unlike the TSC, but it is more expensive to access,
897	  as it is off-chip.  The interface used is documented
898	  in the HPET spec, revision 1.
899
900	  You can safely choose Y here.  However, HPET will only be
901	  activated if the platform and the BIOS support this feature.
902	  Otherwise the 8254 will be used for timing services.
903
904	  Choose N to continue using the legacy 8254 timer.
905
906config HPET_EMULATE_RTC
907	def_bool y
908	depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
909
910# Mark as expert because too many people got it wrong.
911# The code disables itself when not needed.
912config DMI
913	default y
914	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
915	bool "Enable DMI scanning" if EXPERT
916	help
917	  Enabled scanning of DMI to identify machine quirks. Say Y
918	  here unless you have verified that your setup is not
919	  affected by entries in the DMI blacklist. Required by PNP
920	  BIOS code.
921
922config GART_IOMMU
923	bool "Old AMD GART IOMMU support"
924	select DMA_OPS
925	select IOMMU_HELPER
926	select SWIOTLB
927	depends on X86_64 && PCI && AMD_NB
928	help
929	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
930	  GART based hardware IOMMUs.
931
932	  The GART supports full DMA access for devices with 32-bit access
933	  limitations, on systems with more than 3 GB. This is usually needed
934	  for USB, sound, many IDE/SATA chipsets and some other devices.
935
936	  Newer systems typically have a modern AMD IOMMU, supported via
937	  the CONFIG_AMD_IOMMU=y config option.
938
939	  In normal configurations this driver is only active when needed:
940	  there's more than 3 GB of memory and the system contains a
941	  32-bit limited device.
942
943	  If unsure, say Y.
944
945config BOOT_VESA_SUPPORT
946	bool
947	help
948	  If true, at least one selected framebuffer driver can take advantage
949	  of VESA video modes set at an early boot stage via the vga= parameter.
950
951config MAXSMP
952	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
953	depends on X86_64 && SMP && DEBUG_KERNEL
954	select CPUMASK_OFFSTACK
955	help
956	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
957	  If unsure, say N.
958
959#
960# The maximum number of CPUs supported:
961#
962# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
963# and which can be configured interactively in the
964# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
965#
966# The ranges are different on 32-bit and 64-bit kernels, depending on
967# hardware capabilities and scalability features of the kernel.
968#
969# ( If MAXSMP is enabled we just use the highest possible value and disable
970#   interactive configuration. )
971#
972
973config NR_CPUS_RANGE_BEGIN
974	int
975	default NR_CPUS_RANGE_END if MAXSMP
976	default    1 if !SMP
977	default    2
978
979config NR_CPUS_RANGE_END
980	int
981	depends on X86_32
982	default   64 if  SMP &&  X86_BIGSMP
983	default    8 if  SMP && !X86_BIGSMP
984	default    1 if !SMP
985
986config NR_CPUS_RANGE_END
987	int
988	depends on X86_64
989	default 8192 if  SMP && CPUMASK_OFFSTACK
990	default  512 if  SMP && !CPUMASK_OFFSTACK
991	default    1 if !SMP
992
993config NR_CPUS_DEFAULT
994	int
995	depends on X86_32
996	default   32 if  X86_BIGSMP
997	default    8 if  SMP
998	default    1 if !SMP
999
1000config NR_CPUS_DEFAULT
1001	int
1002	depends on X86_64
1003	default 8192 if  MAXSMP
1004	default   64 if  SMP
1005	default    1 if !SMP
1006
1007config NR_CPUS
1008	int "Maximum number of CPUs" if SMP && !MAXSMP
1009	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1010	default NR_CPUS_DEFAULT
1011	help
1012	  This allows you to specify the maximum number of CPUs which this
1013	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1014	  supported value is 8192, otherwise the maximum value is 512.  The
1015	  minimum value which makes sense is 2.
1016
1017	  This is purely to save memory: each supported CPU adds about 8KB
1018	  to the kernel image.
1019
1020config SCHED_CLUSTER
1021	bool "Cluster scheduler support"
1022	depends on SMP
1023	default y
1024	help
1025	  Cluster scheduler support improves the CPU scheduler's decision
1026	  making when dealing with machines that have clusters of CPUs.
1027	  Cluster usually means a couple of CPUs which are placed closely
1028	  by sharing mid-level caches, last-level cache tags or internal
1029	  busses.
1030
1031config SCHED_SMT
1032	def_bool y if SMP
1033
1034config SCHED_MC
1035	def_bool y
1036	prompt "Multi-core scheduler support"
1037	depends on SMP
1038	help
1039	  Multi-core scheduler support improves the CPU scheduler's decision
1040	  making when dealing with multi-core CPU chips at a cost of slightly
1041	  increased overhead in some places. If unsure say N here.
1042
1043config SCHED_MC_PRIO
1044	bool "CPU core priorities scheduler support"
1045	depends on SCHED_MC && CPU_SUP_INTEL
1046	select X86_INTEL_PSTATE
1047	select CPU_FREQ
1048	default y
1049	help
1050	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1051	  core ordering determined at manufacturing time, which allows
1052	  certain cores to reach higher turbo frequencies (when running
1053	  single threaded workloads) than others.
1054
1055	  Enabling this kernel feature teaches the scheduler about
1056	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1057	  scheduler's CPU selection logic accordingly, so that higher
1058	  overall system performance can be achieved.
1059
1060	  This feature will have no effect on CPUs without this feature.
1061
1062	  If unsure say Y here.
1063
1064config UP_LATE_INIT
1065	def_bool y
1066	depends on !SMP && X86_LOCAL_APIC
1067
1068config X86_UP_APIC
1069	bool "Local APIC support on uniprocessors" if !PCI_MSI
1070	default PCI_MSI
1071	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1072	help
1073	  A local APIC (Advanced Programmable Interrupt Controller) is an
1074	  integrated interrupt controller in the CPU. If you have a single-CPU
1075	  system which has a processor with a local APIC, you can say Y here to
1076	  enable and use it. If you say Y here even though your machine doesn't
1077	  have a local APIC, then the kernel will still run with no slowdown at
1078	  all. The local APIC supports CPU-generated self-interrupts (timer,
1079	  performance counters), and the NMI watchdog which detects hard
1080	  lockups.
1081
1082config X86_UP_IOAPIC
1083	bool "IO-APIC support on uniprocessors"
1084	depends on X86_UP_APIC
1085	help
1086	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1087	  SMP-capable replacement for PC-style interrupt controllers. Most
1088	  SMP systems and many recent uniprocessor systems have one.
1089
1090	  If you have a single-CPU system with an IO-APIC, you can say Y here
1091	  to use it. If you say Y here even though your machine doesn't have
1092	  an IO-APIC, then the kernel will still run with no slowdown at all.
1093
1094config X86_LOCAL_APIC
1095	def_bool y
1096	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1097	select IRQ_DOMAIN_HIERARCHY
1098	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1099
1100config X86_IO_APIC
1101	def_bool y
1102	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1103
1104config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1105	bool "Reroute for broken boot IRQs"
1106	depends on X86_IO_APIC
1107	help
1108	  This option enables a workaround that fixes a source of
1109	  spurious interrupts. This is recommended when threaded
1110	  interrupt handling is used on systems where the generation of
1111	  superfluous "boot interrupts" cannot be disabled.
1112
1113	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1114	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1115	  kernel does during interrupt handling). On chipsets where this
1116	  boot IRQ generation cannot be disabled, this workaround keeps
1117	  the original IRQ line masked so that only the equivalent "boot
1118	  IRQ" is delivered to the CPUs. The workaround also tells the
1119	  kernel to set up the IRQ handler on the boot IRQ line. In this
1120	  way only one interrupt is delivered to the kernel. Otherwise
1121	  the spurious second interrupt may cause the kernel to bring
1122	  down (vital) interrupt lines.
1123
1124	  Only affects "broken" chipsets. Interrupt sharing may be
1125	  increased on these systems.
1126
1127config X86_MCE
1128	bool "Machine Check / overheating reporting"
1129	select GENERIC_ALLOCATOR
1130	default y
1131	help
1132	  Machine Check support allows the processor to notify the
1133	  kernel if it detects a problem (e.g. overheating, data corruption).
1134	  The action the kernel takes depends on the severity of the problem,
1135	  ranging from warning messages to halting the machine.
1136
1137config X86_MCELOG_LEGACY
1138	bool "Support for deprecated /dev/mcelog character device"
1139	depends on X86_MCE
1140	help
1141	  Enable support for /dev/mcelog which is needed by the old mcelog
1142	  userspace logging daemon. Consider switching to the new generation
1143	  rasdaemon solution.
1144
1145config X86_MCE_INTEL
1146	def_bool y
1147	prompt "Intel MCE features"
1148	depends on X86_MCE && X86_LOCAL_APIC
1149	help
1150	  Additional support for intel specific MCE features such as
1151	  the thermal monitor.
1152
1153config X86_MCE_AMD
1154	def_bool y
1155	prompt "AMD MCE features"
1156	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1157	help
1158	  Additional support for AMD specific MCE features such as
1159	  the DRAM Error Threshold.
1160
1161config X86_ANCIENT_MCE
1162	bool "Support for old Pentium 5 / WinChip machine checks"
1163	depends on X86_32 && X86_MCE
1164	help
1165	  Include support for machine check handling on old Pentium 5 or WinChip
1166	  systems. These typically need to be enabled explicitly on the command
1167	  line.
1168
1169config X86_MCE_THRESHOLD
1170	depends on X86_MCE_AMD || X86_MCE_INTEL
1171	def_bool y
1172
1173config X86_MCE_INJECT
1174	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1175	tristate "Machine check injector support"
1176	help
1177	  Provide support for injecting machine checks for testing purposes.
1178	  If you don't know what a machine check is and you don't do kernel
1179	  QA it is safe to say n.
1180
1181source "arch/x86/events/Kconfig"
1182
1183config X86_LEGACY_VM86
1184	bool "Legacy VM86 support"
1185	depends on X86_32
1186	help
1187	  This option allows user programs to put the CPU into V8086
1188	  mode, which is an 80286-era approximation of 16-bit real mode.
1189
1190	  Some very old versions of X and/or vbetool require this option
1191	  for user mode setting.  Similarly, DOSEMU will use it if
1192	  available to accelerate real mode DOS programs.  However, any
1193	  recent version of DOSEMU, X, or vbetool should be fully
1194	  functional even without kernel VM86 support, as they will all
1195	  fall back to software emulation. Nevertheless, if you are using
1196	  a 16-bit DOS program where 16-bit performance matters, vm86
1197	  mode might be faster than emulation and you might want to
1198	  enable this option.
1199
1200	  Note that any app that works on a 64-bit kernel is unlikely to
1201	  need this option, as 64-bit kernels don't, and can't, support
1202	  V8086 mode. This option is also unrelated to 16-bit protected
1203	  mode and is not needed to run most 16-bit programs under Wine.
1204
1205	  Enabling this option increases the complexity of the kernel
1206	  and slows down exception handling a tiny bit.
1207
1208	  If unsure, say N here.
1209
1210config VM86
1211	bool
1212	default X86_LEGACY_VM86
1213
1214config X86_16BIT
1215	bool "Enable support for 16-bit segments" if EXPERT
1216	default y
1217	depends on MODIFY_LDT_SYSCALL
1218	help
1219	  This option is required by programs like Wine to run 16-bit
1220	  protected mode legacy code on x86 processors.  Disabling
1221	  this option saves about 300 bytes on i386, or around 6K text
1222	  plus 16K runtime memory on x86-64,
1223
1224config X86_ESPFIX32
1225	def_bool y
1226	depends on X86_16BIT && X86_32
1227
1228config X86_ESPFIX64
1229	def_bool y
1230	depends on X86_16BIT && X86_64
1231
1232config X86_VSYSCALL_EMULATION
1233	bool "Enable vsyscall emulation" if EXPERT
1234	default y
1235	depends on X86_64
1236	help
1237	  This enables emulation of the legacy vsyscall page.  Disabling
1238	  it is roughly equivalent to booting with vsyscall=none, except
1239	  that it will also disable the helpful warning if a program
1240	  tries to use a vsyscall.  With this option set to N, offending
1241	  programs will just segfault, citing addresses of the form
1242	  0xffffffffff600?00.
1243
1244	  This option is required by many programs built before 2013, and
1245	  care should be used even with newer programs if set to N.
1246
1247	  Disabling this option saves about 7K of kernel size and
1248	  possibly 4K of additional runtime pagetable memory.
1249
1250config X86_IOPL_IOPERM
1251	bool "IOPERM and IOPL Emulation"
1252	default y
1253	help
1254	  This enables the ioperm() and iopl() syscalls which are necessary
1255	  for legacy applications.
1256
1257	  Legacy IOPL support is an overbroad mechanism which allows user
1258	  space aside of accessing all 65536 I/O ports also to disable
1259	  interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1260	  capabilities and permission from potentially active security
1261	  modules.
1262
1263	  The emulation restricts the functionality of the syscall to
1264	  only allowing the full range I/O port access, but prevents the
1265	  ability to disable interrupts from user space which would be
1266	  granted if the hardware IOPL mechanism would be used.
1267
1268config TOSHIBA
1269	tristate "Toshiba Laptop support"
1270	depends on X86_32
1271	help
1272	  This adds a driver to safely access the System Management Mode of
1273	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1274	  not work on models with a Phoenix BIOS. The System Management Mode
1275	  is used to set the BIOS and power saving options on Toshiba portables.
1276
1277	  For information on utilities to make use of this driver see the
1278	  Toshiba Linux utilities web site at:
1279	  <http://www.buzzard.org.uk/toshiba/>.
1280
1281	  Say Y if you intend to run this kernel on a Toshiba portable.
1282	  Say N otherwise.
1283
1284config X86_REBOOTFIXUPS
1285	bool "Enable X86 board specific fixups for reboot"
1286	depends on X86_32
1287	help
1288	  This enables chipset and/or board specific fixups to be done
1289	  in order to get reboot to work correctly. This is only needed on
1290	  some combinations of hardware and BIOS. The symptom, for which
1291	  this config is intended, is when reboot ends with a stalled/hung
1292	  system.
1293
1294	  Currently, the only fixup is for the Geode machines using
1295	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1296
1297	  Say Y if you want to enable the fixup. Currently, it's safe to
1298	  enable this option even if you don't need it.
1299	  Say N otherwise.
1300
1301config MICROCODE
1302	bool "CPU microcode loading support"
1303	default y
1304	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1305	help
1306	  If you say Y here, you will be able to update the microcode on
1307	  Intel and AMD processors. The Intel support is for the IA32 family,
1308	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1309	  AMD support is for families 0x10 and later. You will obviously need
1310	  the actual microcode binary data itself which is not shipped with
1311	  the Linux kernel.
1312
1313	  The preferred method to load microcode from a detached initrd is described
1314	  in Documentation/x86/microcode.rst. For that you need to enable
1315	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1316	  initrd for microcode blobs.
1317
1318	  In addition, you can build the microcode into the kernel. For that you
1319	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1320	  config option.
1321
1322config MICROCODE_INTEL
1323	bool "Intel microcode loading support"
1324	depends on CPU_SUP_INTEL && MICROCODE
1325	default MICROCODE
1326	help
1327	  This options enables microcode patch loading support for Intel
1328	  processors.
1329
1330	  For the current Intel microcode data package go to
1331	  <https://downloadcenter.intel.com> and search for
1332	  'Linux Processor Microcode Data File'.
1333
1334config MICROCODE_AMD
1335	bool "AMD microcode loading support"
1336	depends on CPU_SUP_AMD && MICROCODE
1337	help
1338	  If you select this option, microcode patch loading support for AMD
1339	  processors will be enabled.
1340
1341config MICROCODE_LATE_LOADING
1342	bool "Late microcode loading (DANGEROUS)"
1343	default n
1344	depends on MICROCODE
1345	help
1346	  Loading microcode late, when the system is up and executing instructions
1347	  is a tricky business and should be avoided if possible. Just the sequence
1348	  of synchronizing all cores and SMT threads is one fragile dance which does
1349	  not guarantee that cores might not softlock after the loading. Therefore,
1350	  use this at your own risk. Late loading taints the kernel too.
1351
1352config X86_MSR
1353	tristate "/dev/cpu/*/msr - Model-specific register support"
1354	help
1355	  This device gives privileged processes access to the x86
1356	  Model-Specific Registers (MSRs).  It is a character device with
1357	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1358	  MSR accesses are directed to a specific CPU on multi-processor
1359	  systems.
1360
1361config X86_CPUID
1362	tristate "/dev/cpu/*/cpuid - CPU information support"
1363	help
1364	  This device gives processes access to the x86 CPUID instruction to
1365	  be executed on a specific processor.  It is a character device
1366	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1367	  /dev/cpu/31/cpuid.
1368
1369choice
1370	prompt "High Memory Support"
1371	default HIGHMEM4G
1372	depends on X86_32
1373
1374config NOHIGHMEM
1375	bool "off"
1376	help
1377	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1378	  However, the address space of 32-bit x86 processors is only 4
1379	  Gigabytes large. That means that, if you have a large amount of
1380	  physical memory, not all of it can be "permanently mapped" by the
1381	  kernel. The physical memory that's not permanently mapped is called
1382	  "high memory".
1383
1384	  If you are compiling a kernel which will never run on a machine with
1385	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1386	  choice and suitable for most users). This will result in a "3GB/1GB"
1387	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1388	  space and the remaining part of the 4GB virtual memory space is used
1389	  by the kernel to permanently map as much physical memory as
1390	  possible.
1391
1392	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1393	  answer "4GB" here.
1394
1395	  If more than 4 Gigabytes is used then answer "64GB" here. This
1396	  selection turns Intel PAE (Physical Address Extension) mode on.
1397	  PAE implements 3-level paging on IA32 processors. PAE is fully
1398	  supported by Linux, PAE mode is implemented on all recent Intel
1399	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1400	  then the kernel will not boot on CPUs that don't support PAE!
1401
1402	  The actual amount of total physical memory will either be
1403	  auto detected or can be forced by using a kernel command line option
1404	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1405	  your boot loader (lilo or loadlin) about how to pass options to the
1406	  kernel at boot time.)
1407
1408	  If unsure, say "off".
1409
1410config HIGHMEM4G
1411	bool "4GB"
1412	help
1413	  Select this if you have a 32-bit processor and between 1 and 4
1414	  gigabytes of physical RAM.
1415
1416config HIGHMEM64G
1417	bool "64GB"
1418	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1419	select X86_PAE
1420	help
1421	  Select this if you have a 32-bit processor and more than 4
1422	  gigabytes of physical RAM.
1423
1424endchoice
1425
1426choice
1427	prompt "Memory split" if EXPERT
1428	default VMSPLIT_3G
1429	depends on X86_32
1430	help
1431	  Select the desired split between kernel and user memory.
1432
1433	  If the address range available to the kernel is less than the
1434	  physical memory installed, the remaining memory will be available
1435	  as "high memory". Accessing high memory is a little more costly
1436	  than low memory, as it needs to be mapped into the kernel first.
1437	  Note that increasing the kernel address space limits the range
1438	  available to user programs, making the address space there
1439	  tighter.  Selecting anything other than the default 3G/1G split
1440	  will also likely make your kernel incompatible with binary-only
1441	  kernel modules.
1442
1443	  If you are not absolutely sure what you are doing, leave this
1444	  option alone!
1445
1446	config VMSPLIT_3G
1447		bool "3G/1G user/kernel split"
1448	config VMSPLIT_3G_OPT
1449		depends on !X86_PAE
1450		bool "3G/1G user/kernel split (for full 1G low memory)"
1451	config VMSPLIT_2G
1452		bool "2G/2G user/kernel split"
1453	config VMSPLIT_2G_OPT
1454		depends on !X86_PAE
1455		bool "2G/2G user/kernel split (for full 2G low memory)"
1456	config VMSPLIT_1G
1457		bool "1G/3G user/kernel split"
1458endchoice
1459
1460config PAGE_OFFSET
1461	hex
1462	default 0xB0000000 if VMSPLIT_3G_OPT
1463	default 0x80000000 if VMSPLIT_2G
1464	default 0x78000000 if VMSPLIT_2G_OPT
1465	default 0x40000000 if VMSPLIT_1G
1466	default 0xC0000000
1467	depends on X86_32
1468
1469config HIGHMEM
1470	def_bool y
1471	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1472
1473config X86_PAE
1474	bool "PAE (Physical Address Extension) Support"
1475	depends on X86_32 && !HIGHMEM4G
1476	select PHYS_ADDR_T_64BIT
1477	select SWIOTLB
1478	help
1479	  PAE is required for NX support, and furthermore enables
1480	  larger swapspace support for non-overcommit purposes. It
1481	  has the cost of more pagetable lookup overhead, and also
1482	  consumes more pagetable space per process.
1483
1484config X86_5LEVEL
1485	bool "Enable 5-level page tables support"
1486	default y
1487	select DYNAMIC_MEMORY_LAYOUT
1488	select SPARSEMEM_VMEMMAP
1489	depends on X86_64
1490	help
1491	  5-level paging enables access to larger address space:
1492	  upto 128 PiB of virtual address space and 4 PiB of
1493	  physical address space.
1494
1495	  It will be supported by future Intel CPUs.
1496
1497	  A kernel with the option enabled can be booted on machines that
1498	  support 4- or 5-level paging.
1499
1500	  See Documentation/x86/x86_64/5level-paging.rst for more
1501	  information.
1502
1503	  Say N if unsure.
1504
1505config X86_DIRECT_GBPAGES
1506	def_bool y
1507	depends on X86_64
1508	help
1509	  Certain kernel features effectively disable kernel
1510	  linear 1 GB mappings (even if the CPU otherwise
1511	  supports them), so don't confuse the user by printing
1512	  that we have them enabled.
1513
1514config X86_CPA_STATISTICS
1515	bool "Enable statistic for Change Page Attribute"
1516	depends on DEBUG_FS
1517	help
1518	  Expose statistics about the Change Page Attribute mechanism, which
1519	  helps to determine the effectiveness of preserving large and huge
1520	  page mappings when mapping protections are changed.
1521
1522config X86_MEM_ENCRYPT
1523	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1524	select DYNAMIC_PHYSICAL_MASK
1525	def_bool n
1526
1527config AMD_MEM_ENCRYPT
1528	bool "AMD Secure Memory Encryption (SME) support"
1529	depends on X86_64 && CPU_SUP_AMD
1530	select DMA_COHERENT_POOL
1531	select ARCH_USE_MEMREMAP_PROT
1532	select INSTRUCTION_DECODER
1533	select ARCH_HAS_CC_PLATFORM
1534	select X86_MEM_ENCRYPT
1535	help
1536	  Say yes to enable support for the encryption of system memory.
1537	  This requires an AMD processor that supports Secure Memory
1538	  Encryption (SME).
1539
1540config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1541	bool "Activate AMD Secure Memory Encryption (SME) by default"
1542	depends on AMD_MEM_ENCRYPT
1543	help
1544	  Say yes to have system memory encrypted by default if running on
1545	  an AMD processor that supports Secure Memory Encryption (SME).
1546
1547	  If set to Y, then the encryption of system memory can be
1548	  deactivated with the mem_encrypt=off command line option.
1549
1550	  If set to N, then the encryption of system memory can be
1551	  activated with the mem_encrypt=on command line option.
1552
1553# Common NUMA Features
1554config NUMA
1555	bool "NUMA Memory Allocation and Scheduler Support"
1556	depends on SMP
1557	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1558	default y if X86_BIGSMP
1559	select USE_PERCPU_NUMA_NODE_ID
1560	help
1561	  Enable NUMA (Non-Uniform Memory Access) support.
1562
1563	  The kernel will try to allocate memory used by a CPU on the
1564	  local memory controller of the CPU and add some more
1565	  NUMA awareness to the kernel.
1566
1567	  For 64-bit this is recommended if the system is Intel Core i7
1568	  (or later), AMD Opteron, or EM64T NUMA.
1569
1570	  For 32-bit this is only needed if you boot a 32-bit
1571	  kernel on a 64-bit NUMA platform.
1572
1573	  Otherwise, you should say N.
1574
1575config AMD_NUMA
1576	def_bool y
1577	prompt "Old style AMD Opteron NUMA detection"
1578	depends on X86_64 && NUMA && PCI
1579	help
1580	  Enable AMD NUMA node topology detection.  You should say Y here if
1581	  you have a multi processor AMD system. This uses an old method to
1582	  read the NUMA configuration directly from the builtin Northbridge
1583	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1584	  which also takes priority if both are compiled in.
1585
1586config X86_64_ACPI_NUMA
1587	def_bool y
1588	prompt "ACPI NUMA detection"
1589	depends on X86_64 && NUMA && ACPI && PCI
1590	select ACPI_NUMA
1591	help
1592	  Enable ACPI SRAT based node topology detection.
1593
1594config NUMA_EMU
1595	bool "NUMA emulation"
1596	depends on NUMA
1597	help
1598	  Enable NUMA emulation. A flat machine will be split
1599	  into virtual nodes when booted with "numa=fake=N", where N is the
1600	  number of nodes. This is only useful for debugging.
1601
1602config NODES_SHIFT
1603	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1604	range 1 10
1605	default "10" if MAXSMP
1606	default "6" if X86_64
1607	default "3"
1608	depends on NUMA
1609	help
1610	  Specify the maximum number of NUMA Nodes available on the target
1611	  system.  Increases memory reserved to accommodate various tables.
1612
1613config ARCH_FLATMEM_ENABLE
1614	def_bool y
1615	depends on X86_32 && !NUMA
1616
1617config ARCH_SPARSEMEM_ENABLE
1618	def_bool y
1619	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1620	select SPARSEMEM_STATIC if X86_32
1621	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1622
1623config ARCH_SPARSEMEM_DEFAULT
1624	def_bool X86_64 || (NUMA && X86_32)
1625
1626config ARCH_SELECT_MEMORY_MODEL
1627	def_bool y
1628	depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
1629
1630config ARCH_MEMORY_PROBE
1631	bool "Enable sysfs memory/probe interface"
1632	depends on MEMORY_HOTPLUG
1633	help
1634	  This option enables a sysfs memory/probe interface for testing.
1635	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1636	  If you are unsure how to answer this question, answer N.
1637
1638config ARCH_PROC_KCORE_TEXT
1639	def_bool y
1640	depends on X86_64 && PROC_KCORE
1641
1642config ILLEGAL_POINTER_VALUE
1643	hex
1644	default 0 if X86_32
1645	default 0xdead000000000000 if X86_64
1646
1647config X86_PMEM_LEGACY_DEVICE
1648	bool
1649
1650config X86_PMEM_LEGACY
1651	tristate "Support non-standard NVDIMMs and ADR protected memory"
1652	depends on PHYS_ADDR_T_64BIT
1653	depends on BLK_DEV
1654	select X86_PMEM_LEGACY_DEVICE
1655	select NUMA_KEEP_MEMINFO if NUMA
1656	select LIBNVDIMM
1657	help
1658	  Treat memory marked using the non-standard e820 type of 12 as used
1659	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1660	  The kernel will offer these regions to the 'pmem' driver so
1661	  they can be used for persistent storage.
1662
1663	  Say Y if unsure.
1664
1665config HIGHPTE
1666	bool "Allocate 3rd-level pagetables from highmem"
1667	depends on HIGHMEM
1668	help
1669	  The VM uses one page table entry for each page of physical memory.
1670	  For systems with a lot of RAM, this can be wasteful of precious
1671	  low memory.  Setting this option will put user-space page table
1672	  entries in high memory.
1673
1674config X86_CHECK_BIOS_CORRUPTION
1675	bool "Check for low memory corruption"
1676	help
1677	  Periodically check for memory corruption in low memory, which
1678	  is suspected to be caused by BIOS.  Even when enabled in the
1679	  configuration, it is disabled at runtime.  Enable it by
1680	  setting "memory_corruption_check=1" on the kernel command
1681	  line.  By default it scans the low 64k of memory every 60
1682	  seconds; see the memory_corruption_check_size and
1683	  memory_corruption_check_period parameters in
1684	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1685
1686	  When enabled with the default parameters, this option has
1687	  almost no overhead, as it reserves a relatively small amount
1688	  of memory and scans it infrequently.  It both detects corruption
1689	  and prevents it from affecting the running system.
1690
1691	  It is, however, intended as a diagnostic tool; if repeatable
1692	  BIOS-originated corruption always affects the same memory,
1693	  you can use memmap= to prevent the kernel from using that
1694	  memory.
1695
1696config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1697	bool "Set the default setting of memory_corruption_check"
1698	depends on X86_CHECK_BIOS_CORRUPTION
1699	default y
1700	help
1701	  Set whether the default state of memory_corruption_check is
1702	  on or off.
1703
1704config MATH_EMULATION
1705	bool
1706	depends on MODIFY_LDT_SYSCALL
1707	prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1708	help
1709	  Linux can emulate a math coprocessor (used for floating point
1710	  operations) if you don't have one. 486DX and Pentium processors have
1711	  a math coprocessor built in, 486SX and 386 do not, unless you added
1712	  a 487DX or 387, respectively. (The messages during boot time can
1713	  give you some hints here ["man dmesg"].) Everyone needs either a
1714	  coprocessor or this emulation.
1715
1716	  If you don't have a math coprocessor, you need to say Y here; if you
1717	  say Y here even though you have a coprocessor, the coprocessor will
1718	  be used nevertheless. (This behavior can be changed with the kernel
1719	  command line option "no387", which comes handy if your coprocessor
1720	  is broken. Try "man bootparam" or see the documentation of your boot
1721	  loader (lilo or loadlin) about how to pass options to the kernel at
1722	  boot time.) This means that it is a good idea to say Y here if you
1723	  intend to use this kernel on different machines.
1724
1725	  More information about the internals of the Linux math coprocessor
1726	  emulation can be found in <file:arch/x86/math-emu/README>.
1727
1728	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1729	  kernel, it won't hurt.
1730
1731config MTRR
1732	def_bool y
1733	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1734	help
1735	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1736	  the Memory Type Range Registers (MTRRs) may be used to control
1737	  processor access to memory ranges. This is most useful if you have
1738	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1739	  allows bus write transfers to be combined into a larger transfer
1740	  before bursting over the PCI/AGP bus. This can increase performance
1741	  of image write operations 2.5 times or more. Saying Y here creates a
1742	  /proc/mtrr file which may be used to manipulate your processor's
1743	  MTRRs. Typically the X server should use this.
1744
1745	  This code has a reasonably generic interface so that similar
1746	  control registers on other processors can be easily supported
1747	  as well:
1748
1749	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1750	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1751	  these, the ARRs are used to emulate the MTRRs.
1752	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1753	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1754	  write-combining. All of these processors are supported by this code
1755	  and it makes sense to say Y here if you have one of them.
1756
1757	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1758	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1759	  can lead to all sorts of problems, so it's good to say Y here.
1760
1761	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1762	  just add about 9 KB to your kernel.
1763
1764	  See <file:Documentation/x86/mtrr.rst> for more information.
1765
1766config MTRR_SANITIZER
1767	def_bool y
1768	prompt "MTRR cleanup support"
1769	depends on MTRR
1770	help
1771	  Convert MTRR layout from continuous to discrete, so X drivers can
1772	  add writeback entries.
1773
1774	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1775	  The largest mtrr entry size for a continuous block can be set with
1776	  mtrr_chunk_size.
1777
1778	  If unsure, say Y.
1779
1780config MTRR_SANITIZER_ENABLE_DEFAULT
1781	int "MTRR cleanup enable value (0-1)"
1782	range 0 1
1783	default "0"
1784	depends on MTRR_SANITIZER
1785	help
1786	  Enable mtrr cleanup default value
1787
1788config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1789	int "MTRR cleanup spare reg num (0-7)"
1790	range 0 7
1791	default "1"
1792	depends on MTRR_SANITIZER
1793	help
1794	  mtrr cleanup spare entries default, it can be changed via
1795	  mtrr_spare_reg_nr=N on the kernel command line.
1796
1797config X86_PAT
1798	def_bool y
1799	prompt "x86 PAT support" if EXPERT
1800	depends on MTRR
1801	help
1802	  Use PAT attributes to setup page level cache control.
1803
1804	  PATs are the modern equivalents of MTRRs and are much more
1805	  flexible than MTRRs.
1806
1807	  Say N here if you see bootup problems (boot crash, boot hang,
1808	  spontaneous reboots) or a non-working video driver.
1809
1810	  If unsure, say Y.
1811
1812config ARCH_USES_PG_UNCACHED
1813	def_bool y
1814	depends on X86_PAT
1815
1816config X86_UMIP
1817	def_bool y
1818	prompt "User Mode Instruction Prevention" if EXPERT
1819	help
1820	  User Mode Instruction Prevention (UMIP) is a security feature in
1821	  some x86 processors. If enabled, a general protection fault is
1822	  issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1823	  executed in user mode. These instructions unnecessarily expose
1824	  information about the hardware state.
1825
1826	  The vast majority of applications do not use these instructions.
1827	  For the very few that do, software emulation is provided in
1828	  specific cases in protected and virtual-8086 modes. Emulated
1829	  results are dummy.
1830
1831config CC_HAS_IBT
1832	# GCC >= 9 and binutils >= 2.29
1833	# Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1834	# Clang/LLVM >= 14
1835	# https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1836	# https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
1837	def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1838		  (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
1839		  $(as-instr,endbr64)
1840
1841config X86_KERNEL_IBT
1842	prompt "Indirect Branch Tracking"
1843	bool
1844	depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
1845	# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1846	depends on !LD_IS_LLD || LLD_VERSION >= 140000
1847	select OBJTOOL
1848	help
1849	  Build the kernel with support for Indirect Branch Tracking, a
1850	  hardware support course-grain forward-edge Control Flow Integrity
1851	  protection. It enforces that all indirect calls must land on
1852	  an ENDBR instruction, as such, the compiler will instrument the
1853	  code with them to make this happen.
1854
1855	  In addition to building the kernel with IBT, seal all functions that
1856	  are not indirect call targets, avoiding them ever becoming one.
1857
1858	  This requires LTO like objtool runs and will slow down the build. It
1859	  does significantly reduce the number of ENDBR instructions in the
1860	  kernel image.
1861
1862config X86_INTEL_MEMORY_PROTECTION_KEYS
1863	prompt "Memory Protection Keys"
1864	def_bool y
1865	# Note: only available in 64-bit mode
1866	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1867	select ARCH_USES_HIGH_VMA_FLAGS
1868	select ARCH_HAS_PKEYS
1869	help
1870	  Memory Protection Keys provides a mechanism for enforcing
1871	  page-based protections, but without requiring modification of the
1872	  page tables when an application changes protection domains.
1873
1874	  For details, see Documentation/core-api/protection-keys.rst
1875
1876	  If unsure, say y.
1877
1878choice
1879	prompt "TSX enable mode"
1880	depends on CPU_SUP_INTEL
1881	default X86_INTEL_TSX_MODE_OFF
1882	help
1883	  Intel's TSX (Transactional Synchronization Extensions) feature
1884	  allows to optimize locking protocols through lock elision which
1885	  can lead to a noticeable performance boost.
1886
1887	  On the other hand it has been shown that TSX can be exploited
1888	  to form side channel attacks (e.g. TAA) and chances are there
1889	  will be more of those attacks discovered in the future.
1890
1891	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1892	  might override this decision by tsx=on the command line parameter.
1893	  Even with TSX enabled, the kernel will attempt to enable the best
1894	  possible TAA mitigation setting depending on the microcode available
1895	  for the particular machine.
1896
1897	  This option allows to set the default tsx mode between tsx=on, =off
1898	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1899	  details.
1900
1901	  Say off if not sure, auto if TSX is in use but it should be used on safe
1902	  platforms or on if TSX is in use and the security aspect of tsx is not
1903	  relevant.
1904
1905config X86_INTEL_TSX_MODE_OFF
1906	bool "off"
1907	help
1908	  TSX is disabled if possible - equals to tsx=off command line parameter.
1909
1910config X86_INTEL_TSX_MODE_ON
1911	bool "on"
1912	help
1913	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1914	  line parameter.
1915
1916config X86_INTEL_TSX_MODE_AUTO
1917	bool "auto"
1918	help
1919	  TSX is enabled on TSX capable HW that is believed to be safe against
1920	  side channel attacks- equals the tsx=auto command line parameter.
1921endchoice
1922
1923config X86_SGX
1924	bool "Software Guard eXtensions (SGX)"
1925	depends on X86_64 && CPU_SUP_INTEL
1926	depends on CRYPTO=y
1927	depends on CRYPTO_SHA256=y
1928	select SRCU
1929	select MMU_NOTIFIER
1930	select NUMA_KEEP_MEMINFO if NUMA
1931	select XARRAY_MULTI
1932	help
1933	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1934	  that can be used by applications to set aside private regions of code
1935	  and data, referred to as enclaves. An enclave's private memory can
1936	  only be accessed by code running within the enclave. Accesses from
1937	  outside the enclave, including other enclaves, are disallowed by
1938	  hardware.
1939
1940	  If unsure, say N.
1941
1942config EFI
1943	bool "EFI runtime service support"
1944	depends on ACPI
1945	select UCS2_STRING
1946	select EFI_RUNTIME_WRAPPERS
1947	select ARCH_USE_MEMREMAP_PROT
1948	help
1949	  This enables the kernel to use EFI runtime services that are
1950	  available (such as the EFI variable services).
1951
1952	  This option is only useful on systems that have EFI firmware.
1953	  In addition, you should use the latest ELILO loader available
1954	  at <http://elilo.sourceforge.net> in order to take advantage
1955	  of EFI runtime services. However, even with this option, the
1956	  resultant kernel should continue to boot on existing non-EFI
1957	  platforms.
1958
1959config EFI_STUB
1960	bool "EFI stub support"
1961	depends on EFI
1962	depends on $(cc-option,-mabi=ms) || X86_32
1963	select RELOCATABLE
1964	help
1965	  This kernel feature allows a bzImage to be loaded directly
1966	  by EFI firmware without the use of a bootloader.
1967
1968	  See Documentation/admin-guide/efi-stub.rst for more information.
1969
1970config EFI_MIXED
1971	bool "EFI mixed-mode support"
1972	depends on EFI_STUB && X86_64
1973	help
1974	  Enabling this feature allows a 64-bit kernel to be booted
1975	  on a 32-bit firmware, provided that your CPU supports 64-bit
1976	  mode.
1977
1978	  Note that it is not possible to boot a mixed-mode enabled
1979	  kernel via the EFI boot stub - a bootloader that supports
1980	  the EFI handover protocol must be used.
1981
1982	  If unsure, say N.
1983
1984source "kernel/Kconfig.hz"
1985
1986config KEXEC
1987	bool "kexec system call"
1988	select KEXEC_CORE
1989	help
1990	  kexec is a system call that implements the ability to shutdown your
1991	  current kernel, and to start another kernel.  It is like a reboot
1992	  but it is independent of the system firmware.   And like a reboot
1993	  you can start any kernel with it, not just Linux.
1994
1995	  The name comes from the similarity to the exec system call.
1996
1997	  It is an ongoing process to be certain the hardware in a machine
1998	  is properly shutdown, so do not be surprised if this code does not
1999	  initially work for you.  As of this writing the exact hardware
2000	  interface is strongly in flux, so no good recommendation can be
2001	  made.
2002
2003config KEXEC_FILE
2004	bool "kexec file based system call"
2005	select KEXEC_CORE
2006	select HAVE_IMA_KEXEC if IMA
2007	depends on X86_64
2008	depends on CRYPTO=y
2009	depends on CRYPTO_SHA256=y
2010	help
2011	  This is new version of kexec system call. This system call is
2012	  file based and takes file descriptors as system call argument
2013	  for kernel and initramfs as opposed to list of segments as
2014	  accepted by previous system call.
2015
2016config ARCH_HAS_KEXEC_PURGATORY
2017	def_bool KEXEC_FILE
2018
2019config KEXEC_SIG
2020	bool "Verify kernel signature during kexec_file_load() syscall"
2021	depends on KEXEC_FILE
2022	help
2023
2024	  This option makes the kexec_file_load() syscall check for a valid
2025	  signature of the kernel image.  The image can still be loaded without
2026	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2027	  there's a signature that we can check, then it must be valid.
2028
2029	  In addition to this option, you need to enable signature
2030	  verification for the corresponding kernel image type being
2031	  loaded in order for this to work.
2032
2033config KEXEC_SIG_FORCE
2034	bool "Require a valid signature in kexec_file_load() syscall"
2035	depends on KEXEC_SIG
2036	help
2037	  This option makes kernel signature verification mandatory for
2038	  the kexec_file_load() syscall.
2039
2040config KEXEC_BZIMAGE_VERIFY_SIG
2041	bool "Enable bzImage signature verification support"
2042	depends on KEXEC_SIG
2043	depends on SIGNED_PE_FILE_VERIFICATION
2044	select SYSTEM_TRUSTED_KEYRING
2045	help
2046	  Enable bzImage signature verification support.
2047
2048config CRASH_DUMP
2049	bool "kernel crash dumps"
2050	depends on X86_64 || (X86_32 && HIGHMEM)
2051	help
2052	  Generate crash dump after being started by kexec.
2053	  This should be normally only set in special crash dump kernels
2054	  which are loaded in the main kernel with kexec-tools into
2055	  a specially reserved region and then later executed after
2056	  a crash by kdump/kexec. The crash dump kernel must be compiled
2057	  to a memory address not used by the main kernel or BIOS using
2058	  PHYSICAL_START, or it must be built as a relocatable image
2059	  (CONFIG_RELOCATABLE=y).
2060	  For more details see Documentation/admin-guide/kdump/kdump.rst
2061
2062config KEXEC_JUMP
2063	bool "kexec jump"
2064	depends on KEXEC && HIBERNATION
2065	help
2066	  Jump between original kernel and kexeced kernel and invoke
2067	  code in physical address mode via KEXEC
2068
2069config PHYSICAL_START
2070	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2071	default "0x1000000"
2072	help
2073	  This gives the physical address where the kernel is loaded.
2074
2075	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2076	  bzImage will decompress itself to above physical address and
2077	  run from there. Otherwise, bzImage will run from the address where
2078	  it has been loaded by the boot loader and will ignore above physical
2079	  address.
2080
2081	  In normal kdump cases one does not have to set/change this option
2082	  as now bzImage can be compiled as a completely relocatable image
2083	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2084	  address. This option is mainly useful for the folks who don't want
2085	  to use a bzImage for capturing the crash dump and want to use a
2086	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2087	  to be specifically compiled to run from a specific memory area
2088	  (normally a reserved region) and this option comes handy.
2089
2090	  So if you are using bzImage for capturing the crash dump,
2091	  leave the value here unchanged to 0x1000000 and set
2092	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2093	  for capturing the crash dump change this value to start of
2094	  the reserved region.  In other words, it can be set based on
2095	  the "X" value as specified in the "crashkernel=YM@XM"
2096	  command line boot parameter passed to the panic-ed
2097	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2098	  for more details about crash dumps.
2099
2100	  Usage of bzImage for capturing the crash dump is recommended as
2101	  one does not have to build two kernels. Same kernel can be used
2102	  as production kernel and capture kernel. Above option should have
2103	  gone away after relocatable bzImage support is introduced. But it
2104	  is present because there are users out there who continue to use
2105	  vmlinux for dump capture. This option should go away down the
2106	  line.
2107
2108	  Don't change this unless you know what you are doing.
2109
2110config RELOCATABLE
2111	bool "Build a relocatable kernel"
2112	default y
2113	help
2114	  This builds a kernel image that retains relocation information
2115	  so it can be loaded someplace besides the default 1MB.
2116	  The relocations tend to make the kernel binary about 10% larger,
2117	  but are discarded at runtime.
2118
2119	  One use is for the kexec on panic case where the recovery kernel
2120	  must live at a different physical address than the primary
2121	  kernel.
2122
2123	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2124	  it has been loaded at and the compile time physical address
2125	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2126
2127config RANDOMIZE_BASE
2128	bool "Randomize the address of the kernel image (KASLR)"
2129	depends on RELOCATABLE
2130	default y
2131	help
2132	  In support of Kernel Address Space Layout Randomization (KASLR),
2133	  this randomizes the physical address at which the kernel image
2134	  is decompressed and the virtual address where the kernel
2135	  image is mapped, as a security feature that deters exploit
2136	  attempts relying on knowledge of the location of kernel
2137	  code internals.
2138
2139	  On 64-bit, the kernel physical and virtual addresses are
2140	  randomized separately. The physical address will be anywhere
2141	  between 16MB and the top of physical memory (up to 64TB). The
2142	  virtual address will be randomized from 16MB up to 1GB (9 bits
2143	  of entropy). Note that this also reduces the memory space
2144	  available to kernel modules from 1.5GB to 1GB.
2145
2146	  On 32-bit, the kernel physical and virtual addresses are
2147	  randomized together. They will be randomized from 16MB up to
2148	  512MB (8 bits of entropy).
2149
2150	  Entropy is generated using the RDRAND instruction if it is
2151	  supported. If RDTSC is supported, its value is mixed into
2152	  the entropy pool as well. If neither RDRAND nor RDTSC are
2153	  supported, then entropy is read from the i8254 timer. The
2154	  usable entropy is limited by the kernel being built using
2155	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2156	  minimum of 2MB. As a result, only 10 bits of entropy are
2157	  theoretically possible, but the implementations are further
2158	  limited due to memory layouts.
2159
2160	  If unsure, say Y.
2161
2162# Relocation on x86 needs some additional build support
2163config X86_NEED_RELOCS
2164	def_bool y
2165	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2166
2167config PHYSICAL_ALIGN
2168	hex "Alignment value to which kernel should be aligned"
2169	default "0x200000"
2170	range 0x2000 0x1000000 if X86_32
2171	range 0x200000 0x1000000 if X86_64
2172	help
2173	  This value puts the alignment restrictions on physical address
2174	  where kernel is loaded and run from. Kernel is compiled for an
2175	  address which meets above alignment restriction.
2176
2177	  If bootloader loads the kernel at a non-aligned address and
2178	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2179	  address aligned to above value and run from there.
2180
2181	  If bootloader loads the kernel at a non-aligned address and
2182	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2183	  load address and decompress itself to the address it has been
2184	  compiled for and run from there. The address for which kernel is
2185	  compiled already meets above alignment restrictions. Hence the
2186	  end result is that kernel runs from a physical address meeting
2187	  above alignment restrictions.
2188
2189	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2190	  this value must be a multiple of 0x200000.
2191
2192	  Don't change this unless you know what you are doing.
2193
2194config DYNAMIC_MEMORY_LAYOUT
2195	bool
2196	help
2197	  This option makes base addresses of vmalloc and vmemmap as well as
2198	  __PAGE_OFFSET movable during boot.
2199
2200config RANDOMIZE_MEMORY
2201	bool "Randomize the kernel memory sections"
2202	depends on X86_64
2203	depends on RANDOMIZE_BASE
2204	select DYNAMIC_MEMORY_LAYOUT
2205	default RANDOMIZE_BASE
2206	help
2207	  Randomizes the base virtual address of kernel memory sections
2208	  (physical memory mapping, vmalloc & vmemmap). This security feature
2209	  makes exploits relying on predictable memory locations less reliable.
2210
2211	  The order of allocations remains unchanged. Entropy is generated in
2212	  the same way as RANDOMIZE_BASE. Current implementation in the optimal
2213	  configuration have in average 30,000 different possible virtual
2214	  addresses for each memory section.
2215
2216	  If unsure, say Y.
2217
2218config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2219	hex "Physical memory mapping padding" if EXPERT
2220	depends on RANDOMIZE_MEMORY
2221	default "0xa" if MEMORY_HOTPLUG
2222	default "0x0"
2223	range 0x1 0x40 if MEMORY_HOTPLUG
2224	range 0x0 0x40
2225	help
2226	  Define the padding in terabytes added to the existing physical
2227	  memory size during kernel memory randomization. It is useful
2228	  for memory hotplug support but reduces the entropy available for
2229	  address randomization.
2230
2231	  If unsure, leave at the default value.
2232
2233config HOTPLUG_CPU
2234	def_bool y
2235	depends on SMP
2236
2237config BOOTPARAM_HOTPLUG_CPU0
2238	bool "Set default setting of cpu0_hotpluggable"
2239	depends on HOTPLUG_CPU
2240	help
2241	  Set whether default state of cpu0_hotpluggable is on or off.
2242
2243	  Say Y here to enable CPU0 hotplug by default. If this switch
2244	  is turned on, there is no need to give cpu0_hotplug kernel
2245	  parameter and the CPU0 hotplug feature is enabled by default.
2246
2247	  Please note: there are two known CPU0 dependencies if you want
2248	  to enable the CPU0 hotplug feature either by this switch or by
2249	  cpu0_hotplug kernel parameter.
2250
2251	  First, resume from hibernate or suspend always starts from CPU0.
2252	  So hibernate and suspend are prevented if CPU0 is offline.
2253
2254	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2255	  offline if any interrupt can not migrate out of CPU0. There may
2256	  be other CPU0 dependencies.
2257
2258	  Please make sure the dependencies are under your control before
2259	  you enable this feature.
2260
2261	  Say N if you don't want to enable CPU0 hotplug feature by default.
2262	  You still can enable the CPU0 hotplug feature at boot by kernel
2263	  parameter cpu0_hotplug.
2264
2265config DEBUG_HOTPLUG_CPU0
2266	def_bool n
2267	prompt "Debug CPU0 hotplug"
2268	depends on HOTPLUG_CPU
2269	help
2270	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2271	  soon as possible and boots up userspace with CPU0 offlined. User
2272	  can online CPU0 back after boot time.
2273
2274	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2275	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2276	  compilation or giving cpu0_hotplug kernel parameter at boot.
2277
2278	  If unsure, say N.
2279
2280config COMPAT_VDSO
2281	def_bool n
2282	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2283	depends on COMPAT_32
2284	help
2285	  Certain buggy versions of glibc will crash if they are
2286	  presented with a 32-bit vDSO that is not mapped at the address
2287	  indicated in its segment table.
2288
2289	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2290	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2291	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2292	  the only released version with the bug, but OpenSUSE 9
2293	  contains a buggy "glibc 2.3.2".
2294
2295	  The symptom of the bug is that everything crashes on startup, saying:
2296	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2297
2298	  Saying Y here changes the default value of the vdso32 boot
2299	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2300	  This works around the glibc bug but hurts performance.
2301
2302	  If unsure, say N: if you are compiling your own kernel, you
2303	  are unlikely to be using a buggy version of glibc.
2304
2305choice
2306	prompt "vsyscall table for legacy applications"
2307	depends on X86_64
2308	default LEGACY_VSYSCALL_XONLY
2309	help
2310	  Legacy user code that does not know how to find the vDSO expects
2311	  to be able to issue three syscalls by calling fixed addresses in
2312	  kernel space. Since this location is not randomized with ASLR,
2313	  it can be used to assist security vulnerability exploitation.
2314
2315	  This setting can be changed at boot time via the kernel command
2316	  line parameter vsyscall=[emulate|xonly|none].  Emulate mode
2317	  is deprecated and can only be enabled using the kernel command
2318	  line.
2319
2320	  On a system with recent enough glibc (2.14 or newer) and no
2321	  static binaries, you can say None without a performance penalty
2322	  to improve security.
2323
2324	  If unsure, select "Emulate execution only".
2325
2326	config LEGACY_VSYSCALL_XONLY
2327		bool "Emulate execution only"
2328		help
2329		  The kernel traps and emulates calls into the fixed vsyscall
2330		  address mapping and does not allow reads.  This
2331		  configuration is recommended when userspace might use the
2332		  legacy vsyscall area but support for legacy binary
2333		  instrumentation of legacy code is not needed.  It mitigates
2334		  certain uses of the vsyscall area as an ASLR-bypassing
2335		  buffer.
2336
2337	config LEGACY_VSYSCALL_NONE
2338		bool "None"
2339		help
2340		  There will be no vsyscall mapping at all. This will
2341		  eliminate any risk of ASLR bypass due to the vsyscall
2342		  fixed address mapping. Attempts to use the vsyscalls
2343		  will be reported to dmesg, so that either old or
2344		  malicious userspace programs can be identified.
2345
2346endchoice
2347
2348config CMDLINE_BOOL
2349	bool "Built-in kernel command line"
2350	help
2351	  Allow for specifying boot arguments to the kernel at
2352	  build time.  On some systems (e.g. embedded ones), it is
2353	  necessary or convenient to provide some or all of the
2354	  kernel boot arguments with the kernel itself (that is,
2355	  to not rely on the boot loader to provide them.)
2356
2357	  To compile command line arguments into the kernel,
2358	  set this option to 'Y', then fill in the
2359	  boot arguments in CONFIG_CMDLINE.
2360
2361	  Systems with fully functional boot loaders (i.e. non-embedded)
2362	  should leave this option set to 'N'.
2363
2364config CMDLINE
2365	string "Built-in kernel command string"
2366	depends on CMDLINE_BOOL
2367	default ""
2368	help
2369	  Enter arguments here that should be compiled into the kernel
2370	  image and used at boot time.  If the boot loader provides a
2371	  command line at boot time, it is appended to this string to
2372	  form the full kernel command line, when the system boots.
2373
2374	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2375	  change this behavior.
2376
2377	  In most cases, the command line (whether built-in or provided
2378	  by the boot loader) should specify the device for the root
2379	  file system.
2380
2381config CMDLINE_OVERRIDE
2382	bool "Built-in command line overrides boot loader arguments"
2383	depends on CMDLINE_BOOL && CMDLINE != ""
2384	help
2385	  Set this option to 'Y' to have the kernel ignore the boot loader
2386	  command line, and use ONLY the built-in command line.
2387
2388	  This is used to work around broken boot loaders.  This should
2389	  be set to 'N' under normal conditions.
2390
2391config MODIFY_LDT_SYSCALL
2392	bool "Enable the LDT (local descriptor table)" if EXPERT
2393	default y
2394	help
2395	  Linux can allow user programs to install a per-process x86
2396	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2397	  call.  This is required to run 16-bit or segmented code such as
2398	  DOSEMU or some Wine programs.  It is also used by some very old
2399	  threading libraries.
2400
2401	  Enabling this feature adds a small amount of overhead to
2402	  context switches and increases the low-level kernel attack
2403	  surface.  Disabling it removes the modify_ldt(2) system call.
2404
2405	  Saying 'N' here may make sense for embedded or server kernels.
2406
2407config STRICT_SIGALTSTACK_SIZE
2408	bool "Enforce strict size checking for sigaltstack"
2409	depends on DYNAMIC_SIGFRAME
2410	help
2411	  For historical reasons MINSIGSTKSZ is a constant which became
2412	  already too small with AVX512 support. Add a mechanism to
2413	  enforce strict checking of the sigaltstack size against the
2414	  real size of the FPU frame. This option enables the check
2415	  by default. It can also be controlled via the kernel command
2416	  line option 'strict_sas_size' independent of this config
2417	  switch. Enabling it might break existing applications which
2418	  allocate a too small sigaltstack but 'work' because they
2419	  never get a signal delivered.
2420
2421	  Say 'N' unless you want to really enforce this check.
2422
2423source "kernel/livepatch/Kconfig"
2424
2425endmenu
2426
2427config CC_HAS_SLS
2428	def_bool $(cc-option,-mharden-sls=all)
2429
2430config CC_HAS_RETURN_THUNK
2431	def_bool $(cc-option,-mfunction-return=thunk-extern)
2432
2433menuconfig SPECULATION_MITIGATIONS
2434	bool "Mitigations for speculative execution vulnerabilities"
2435	default y
2436	help
2437	  Say Y here to enable options which enable mitigations for
2438	  speculative execution hardware vulnerabilities.
2439
2440	  If you say N, all mitigations will be disabled. You really
2441	  should know what you are doing to say so.
2442
2443if SPECULATION_MITIGATIONS
2444
2445config PAGE_TABLE_ISOLATION
2446	bool "Remove the kernel mapping in user mode"
2447	default y
2448	depends on (X86_64 || X86_PAE)
2449	help
2450	  This feature reduces the number of hardware side channels by
2451	  ensuring that the majority of kernel addresses are not mapped
2452	  into userspace.
2453
2454	  See Documentation/x86/pti.rst for more details.
2455
2456config RETPOLINE
2457	bool "Avoid speculative indirect branches in kernel"
2458	select OBJTOOL if HAVE_OBJTOOL
2459	default y
2460	help
2461	  Compile kernel with the retpoline compiler options to guard against
2462	  kernel-to-user data leaks by avoiding speculative indirect
2463	  branches. Requires a compiler with -mindirect-branch=thunk-extern
2464	  support for full protection. The kernel may run slower.
2465
2466config RETHUNK
2467	bool "Enable return-thunks"
2468	depends on RETPOLINE && CC_HAS_RETURN_THUNK
2469	select OBJTOOL if HAVE_OBJTOOL
2470	default y if X86_64
2471	help
2472	  Compile the kernel with the return-thunks compiler option to guard
2473	  against kernel-to-user data leaks by avoiding return speculation.
2474	  Requires a compiler with -mfunction-return=thunk-extern
2475	  support for full protection. The kernel may run slower.
2476
2477config CPU_UNRET_ENTRY
2478	bool "Enable UNRET on kernel entry"
2479	depends on CPU_SUP_AMD && RETHUNK && X86_64
2480	default y
2481	help
2482	  Compile the kernel with support for the retbleed=unret mitigation.
2483
2484config CPU_IBPB_ENTRY
2485	bool "Enable IBPB on kernel entry"
2486	depends on CPU_SUP_AMD && X86_64
2487	default y
2488	help
2489	  Compile the kernel with support for the retbleed=ibpb mitigation.
2490
2491config CPU_IBRS_ENTRY
2492	bool "Enable IBRS on kernel entry"
2493	depends on CPU_SUP_INTEL && X86_64
2494	default y
2495	help
2496	  Compile the kernel with support for the spectre_v2=ibrs mitigation.
2497	  This mitigates both spectre_v2 and retbleed at great cost to
2498	  performance.
2499
2500config SLS
2501	bool "Mitigate Straight-Line-Speculation"
2502	depends on CC_HAS_SLS && X86_64
2503	select OBJTOOL if HAVE_OBJTOOL
2504	default n
2505	help
2506	  Compile the kernel with straight-line-speculation options to guard
2507	  against straight line speculation. The kernel image might be slightly
2508	  larger.
2509
2510endif
2511
2512config ARCH_HAS_ADD_PAGES
2513	def_bool y
2514	depends on ARCH_ENABLE_MEMORY_HOTPLUG
2515
2516config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2517	def_bool y
2518
2519menu "Power management and ACPI options"
2520
2521config ARCH_HIBERNATION_HEADER
2522	def_bool y
2523	depends on HIBERNATION
2524
2525source "kernel/power/Kconfig"
2526
2527source "drivers/acpi/Kconfig"
2528
2529config X86_APM_BOOT
2530	def_bool y
2531	depends on APM
2532
2533menuconfig APM
2534	tristate "APM (Advanced Power Management) BIOS support"
2535	depends on X86_32 && PM_SLEEP
2536	help
2537	  APM is a BIOS specification for saving power using several different
2538	  techniques. This is mostly useful for battery powered laptops with
2539	  APM compliant BIOSes. If you say Y here, the system time will be
2540	  reset after a RESUME operation, the /proc/apm device will provide
2541	  battery status information, and user-space programs will receive
2542	  notification of APM "events" (e.g. battery status change).
2543
2544	  If you select "Y" here, you can disable actual use of the APM
2545	  BIOS by passing the "apm=off" option to the kernel at boot time.
2546
2547	  Note that the APM support is almost completely disabled for
2548	  machines with more than one CPU.
2549
2550	  In order to use APM, you will need supporting software. For location
2551	  and more information, read <file:Documentation/power/apm-acpi.rst>
2552	  and the Battery Powered Linux mini-HOWTO, available from
2553	  <http://www.tldp.org/docs.html#howto>.
2554
2555	  This driver does not spin down disk drives (see the hdparm(8)
2556	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2557	  VESA-compliant "green" monitors.
2558
2559	  This driver does not support the TI 4000M TravelMate and the ACER
2560	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2561	  desktop machines also don't have compliant BIOSes, and this driver
2562	  may cause those machines to panic during the boot phase.
2563
2564	  Generally, if you don't have a battery in your machine, there isn't
2565	  much point in using this driver and you should say N. If you get
2566	  random kernel OOPSes or reboots that don't seem to be related to
2567	  anything, try disabling/enabling this option (or disabling/enabling
2568	  APM in your BIOS).
2569
2570	  Some other things you should try when experiencing seemingly random,
2571	  "weird" problems:
2572
2573	  1) make sure that you have enough swap space and that it is
2574	  enabled.
2575	  2) pass the "no-hlt" option to the kernel
2576	  3) switch on floating point emulation in the kernel and pass
2577	  the "no387" option to the kernel
2578	  4) pass the "floppy=nodma" option to the kernel
2579	  5) pass the "mem=4M" option to the kernel (thereby disabling
2580	  all but the first 4 MB of RAM)
2581	  6) make sure that the CPU is not over clocked.
2582	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2583	  8) disable the cache from your BIOS settings
2584	  9) install a fan for the video card or exchange video RAM
2585	  10) install a better fan for the CPU
2586	  11) exchange RAM chips
2587	  12) exchange the motherboard.
2588
2589	  To compile this driver as a module, choose M here: the
2590	  module will be called apm.
2591
2592if APM
2593
2594config APM_IGNORE_USER_SUSPEND
2595	bool "Ignore USER SUSPEND"
2596	help
2597	  This option will ignore USER SUSPEND requests. On machines with a
2598	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2599	  series notebooks, it is necessary to say Y because of a BIOS bug.
2600
2601config APM_DO_ENABLE
2602	bool "Enable PM at boot time"
2603	help
2604	  Enable APM features at boot time. From page 36 of the APM BIOS
2605	  specification: "When disabled, the APM BIOS does not automatically
2606	  power manage devices, enter the Standby State, enter the Suspend
2607	  State, or take power saving steps in response to CPU Idle calls."
2608	  This driver will make CPU Idle calls when Linux is idle (unless this
2609	  feature is turned off -- see "Do CPU IDLE calls", below). This
2610	  should always save battery power, but more complicated APM features
2611	  will be dependent on your BIOS implementation. You may need to turn
2612	  this option off if your computer hangs at boot time when using APM
2613	  support, or if it beeps continuously instead of suspending. Turn
2614	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2615	  T400CDT. This is off by default since most machines do fine without
2616	  this feature.
2617
2618config APM_CPU_IDLE
2619	depends on CPU_IDLE
2620	bool "Make CPU Idle calls when idle"
2621	help
2622	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2623	  On some machines, this can activate improved power savings, such as
2624	  a slowed CPU clock rate, when the machine is idle. These idle calls
2625	  are made after the idle loop has run for some length of time (e.g.,
2626	  333 mS). On some machines, this will cause a hang at boot time or
2627	  whenever the CPU becomes idle. (On machines with more than one CPU,
2628	  this option does nothing.)
2629
2630config APM_DISPLAY_BLANK
2631	bool "Enable console blanking using APM"
2632	help
2633	  Enable console blanking using the APM. Some laptops can use this to
2634	  turn off the LCD backlight when the screen blanker of the Linux
2635	  virtual console blanks the screen. Note that this is only used by
2636	  the virtual console screen blanker, and won't turn off the backlight
2637	  when using the X Window system. This also doesn't have anything to
2638	  do with your VESA-compliant power-saving monitor. Further, this
2639	  option doesn't work for all laptops -- it might not turn off your
2640	  backlight at all, or it might print a lot of errors to the console,
2641	  especially if you are using gpm.
2642
2643config APM_ALLOW_INTS
2644	bool "Allow interrupts during APM BIOS calls"
2645	help
2646	  Normally we disable external interrupts while we are making calls to
2647	  the APM BIOS as a measure to lessen the effects of a badly behaving
2648	  BIOS implementation.  The BIOS should reenable interrupts if it
2649	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2650	  many of the newer IBM Thinkpads.  If you experience hangs when you
2651	  suspend, try setting this to Y.  Otherwise, say N.
2652
2653endif # APM
2654
2655source "drivers/cpufreq/Kconfig"
2656
2657source "drivers/cpuidle/Kconfig"
2658
2659source "drivers/idle/Kconfig"
2660
2661endmenu
2662
2663menu "Bus options (PCI etc.)"
2664
2665choice
2666	prompt "PCI access mode"
2667	depends on X86_32 && PCI
2668	default PCI_GOANY
2669	help
2670	  On PCI systems, the BIOS can be used to detect the PCI devices and
2671	  determine their configuration. However, some old PCI motherboards
2672	  have BIOS bugs and may crash if this is done. Also, some embedded
2673	  PCI-based systems don't have any BIOS at all. Linux can also try to
2674	  detect the PCI hardware directly without using the BIOS.
2675
2676	  With this option, you can specify how Linux should detect the
2677	  PCI devices. If you choose "BIOS", the BIOS will be used,
2678	  if you choose "Direct", the BIOS won't be used, and if you
2679	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2680	  If you choose "Any", the kernel will try MMCONFIG, then the
2681	  direct access method and falls back to the BIOS if that doesn't
2682	  work. If unsure, go with the default, which is "Any".
2683
2684config PCI_GOBIOS
2685	bool "BIOS"
2686
2687config PCI_GOMMCONFIG
2688	bool "MMConfig"
2689
2690config PCI_GODIRECT
2691	bool "Direct"
2692
2693config PCI_GOOLPC
2694	bool "OLPC XO-1"
2695	depends on OLPC
2696
2697config PCI_GOANY
2698	bool "Any"
2699
2700endchoice
2701
2702config PCI_BIOS
2703	def_bool y
2704	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2705
2706# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2707config PCI_DIRECT
2708	def_bool y
2709	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2710
2711config PCI_MMCONFIG
2712	bool "Support mmconfig PCI config space access" if X86_64
2713	default y
2714	depends on PCI && (ACPI || JAILHOUSE_GUEST)
2715	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2716
2717config PCI_OLPC
2718	def_bool y
2719	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2720
2721config PCI_XEN
2722	def_bool y
2723	depends on PCI && XEN
2724
2725config MMCONF_FAM10H
2726	def_bool y
2727	depends on X86_64 && PCI_MMCONFIG && ACPI
2728
2729config PCI_CNB20LE_QUIRK
2730	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2731	depends on PCI
2732	help
2733	  Read the PCI windows out of the CNB20LE host bridge. This allows
2734	  PCI hotplug to work on systems with the CNB20LE chipset which do
2735	  not have ACPI.
2736
2737	  There's no public spec for this chipset, and this functionality
2738	  is known to be incomplete.
2739
2740	  You should say N unless you know you need this.
2741
2742config ISA_BUS
2743	bool "ISA bus support on modern systems" if EXPERT
2744	help
2745	  Expose ISA bus device drivers and options available for selection and
2746	  configuration. Enable this option if your target machine has an ISA
2747	  bus. ISA is an older system, displaced by PCI and newer bus
2748	  architectures -- if your target machine is modern, it probably does
2749	  not have an ISA bus.
2750
2751	  If unsure, say N.
2752
2753# x86_64 have no ISA slots, but can have ISA-style DMA.
2754config ISA_DMA_API
2755	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2756	default y
2757	help
2758	  Enables ISA-style DMA support for devices requiring such controllers.
2759	  If unsure, say Y.
2760
2761if X86_32
2762
2763config ISA
2764	bool "ISA support"
2765	help
2766	  Find out whether you have ISA slots on your motherboard.  ISA is the
2767	  name of a bus system, i.e. the way the CPU talks to the other stuff
2768	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2769	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2770	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2771
2772config SCx200
2773	tristate "NatSemi SCx200 support"
2774	help
2775	  This provides basic support for National Semiconductor's
2776	  (now AMD's) Geode processors.  The driver probes for the
2777	  PCI-IDs of several on-chip devices, so its a good dependency
2778	  for other scx200_* drivers.
2779
2780	  If compiled as a module, the driver is named scx200.
2781
2782config SCx200HR_TIMER
2783	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2784	depends on SCx200
2785	default y
2786	help
2787	  This driver provides a clocksource built upon the on-chip
2788	  27MHz high-resolution timer.  Its also a workaround for
2789	  NSC Geode SC-1100's buggy TSC, which loses time when the
2790	  processor goes idle (as is done by the scheduler).  The
2791	  other workaround is idle=poll boot option.
2792
2793config OLPC
2794	bool "One Laptop Per Child support"
2795	depends on !X86_PAE
2796	select GPIOLIB
2797	select OF
2798	select OF_PROMTREE
2799	select IRQ_DOMAIN
2800	select OLPC_EC
2801	help
2802	  Add support for detecting the unique features of the OLPC
2803	  XO hardware.
2804
2805config OLPC_XO1_PM
2806	bool "OLPC XO-1 Power Management"
2807	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2808	help
2809	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2810
2811config OLPC_XO1_RTC
2812	bool "OLPC XO-1 Real Time Clock"
2813	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2814	help
2815	  Add support for the XO-1 real time clock, which can be used as a
2816	  programmable wakeup source.
2817
2818config OLPC_XO1_SCI
2819	bool "OLPC XO-1 SCI extras"
2820	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2821	depends on INPUT=y
2822	select POWER_SUPPLY
2823	help
2824	  Add support for SCI-based features of the OLPC XO-1 laptop:
2825	   - EC-driven system wakeups
2826	   - Power button
2827	   - Ebook switch
2828	   - Lid switch
2829	   - AC adapter status updates
2830	   - Battery status updates
2831
2832config OLPC_XO15_SCI
2833	bool "OLPC XO-1.5 SCI extras"
2834	depends on OLPC && ACPI
2835	select POWER_SUPPLY
2836	help
2837	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2838	   - EC-driven system wakeups
2839	   - AC adapter status updates
2840	   - Battery status updates
2841
2842config ALIX
2843	bool "PCEngines ALIX System Support (LED setup)"
2844	select GPIOLIB
2845	help
2846	  This option enables system support for the PCEngines ALIX.
2847	  At present this just sets up LEDs for GPIO control on
2848	  ALIX2/3/6 boards.  However, other system specific setup should
2849	  get added here.
2850
2851	  Note: You must still enable the drivers for GPIO and LED support
2852	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2853
2854	  Note: You have to set alix.force=1 for boards with Award BIOS.
2855
2856config NET5501
2857	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2858	select GPIOLIB
2859	help
2860	  This option enables system support for the Soekris Engineering net5501.
2861
2862config GEOS
2863	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2864	select GPIOLIB
2865	depends on DMI
2866	help
2867	  This option enables system support for the Traverse Technologies GEOS.
2868
2869config TS5500
2870	bool "Technologic Systems TS-5500 platform support"
2871	depends on MELAN
2872	select CHECK_SIGNATURE
2873	select NEW_LEDS
2874	select LEDS_CLASS
2875	help
2876	  This option enables system support for the Technologic Systems TS-5500.
2877
2878endif # X86_32
2879
2880config AMD_NB
2881	def_bool y
2882	depends on CPU_SUP_AMD && PCI
2883
2884endmenu
2885
2886menu "Binary Emulations"
2887
2888config IA32_EMULATION
2889	bool "IA32 Emulation"
2890	depends on X86_64
2891	select ARCH_WANT_OLD_COMPAT_IPC
2892	select BINFMT_ELF
2893	select COMPAT_OLD_SIGACTION
2894	help
2895	  Include code to run legacy 32-bit programs under a
2896	  64-bit kernel. You should likely turn this on, unless you're
2897	  100% sure that you don't have any 32-bit programs left.
2898
2899config X86_X32_ABI
2900	bool "x32 ABI for 64-bit mode"
2901	depends on X86_64
2902	# llvm-objcopy does not convert x86_64 .note.gnu.property or
2903	# compressed debug sections to x86_x32 properly:
2904	# https://github.com/ClangBuiltLinux/linux/issues/514
2905	# https://github.com/ClangBuiltLinux/linux/issues/1141
2906	depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
2907	help
2908	  Include code to run binaries for the x32 native 32-bit ABI
2909	  for 64-bit processors.  An x32 process gets access to the
2910	  full 64-bit register file and wide data path while leaving
2911	  pointers at 32 bits for smaller memory footprint.
2912
2913config COMPAT_32
2914	def_bool y
2915	depends on IA32_EMULATION || X86_32
2916	select HAVE_UID16
2917	select OLD_SIGSUSPEND3
2918
2919config COMPAT
2920	def_bool y
2921	depends on IA32_EMULATION || X86_X32_ABI
2922
2923config COMPAT_FOR_U64_ALIGNMENT
2924	def_bool y
2925	depends on COMPAT
2926
2927endmenu
2928
2929config HAVE_ATOMIC_IOMAP
2930	def_bool y
2931	depends on X86_32
2932
2933source "arch/x86/kvm/Kconfig"
2934
2935source "arch/x86/Kconfig.assembler"
2936