xref: /openbmc/linux/arch/x86/Kconfig (revision fb8d6c8d)
1# SPDX-License-Identifier: GPL-2.0
2# Select 32 or 64 bit
3config 64BIT
4	bool "64-bit kernel" if "$(ARCH)" = "x86"
5	default "$(ARCH)" != "i386"
6	---help---
7	  Say yes to build a 64-bit kernel - formerly known as x86_64
8	  Say no to build a 32-bit kernel - formerly known as i386
9
10config X86_32
11	def_bool y
12	depends on !64BIT
13	# Options that are inherently 32-bit kernel only:
14	select ARCH_WANT_IPC_PARSE_VERSION
15	select CLKSRC_I8253
16	select CLONE_BACKWARDS
17	select HAVE_DEBUG_STACKOVERFLOW
18	select MODULES_USE_ELF_REL
19	select OLD_SIGACTION
20	select GENERIC_VDSO_32
21
22config X86_64
23	def_bool y
24	depends on 64BIT
25	# Options that are inherently 64-bit kernel only:
26	select ARCH_HAS_GIGANTIC_PAGE
27	select ARCH_SUPPORTS_INT128
28	select ARCH_USE_CMPXCHG_LOCKREF
29	select HAVE_ARCH_SOFT_DIRTY
30	select MODULES_USE_ELF_RELA
31	select NEED_DMA_MAP_STATE
32	select SWIOTLB
33	select ARCH_HAS_SYSCALL_WRAPPER
34
35config FORCE_DYNAMIC_FTRACE
36	def_bool y
37	depends on X86_32
38	depends on FUNCTION_TRACER
39	select DYNAMIC_FTRACE
40	help
41	 We keep the static function tracing (!DYNAMIC_FTRACE) around
42	 in order to test the non static function tracing in the
43	 generic code, as other architectures still use it. But we
44	 only need to keep it around for x86_64. No need to keep it
45	 for x86_32. For x86_32, force DYNAMIC_FTRACE.
46#
47# Arch settings
48#
49# ( Note that options that are marked 'if X86_64' could in principle be
50#   ported to 32-bit as well. )
51#
52config X86
53	def_bool y
54	#
55	# Note: keep this list sorted alphabetically
56	#
57	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
58	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
59	select ARCH_32BIT_OFF_T			if X86_32
60	select ARCH_CLOCKSOURCE_DATA
61	select ARCH_CLOCKSOURCE_INIT
62	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
63	select ARCH_HAS_DEBUG_VIRTUAL
64	select ARCH_HAS_DEVMEM_IS_ALLOWED
65	select ARCH_HAS_ELF_RANDOMIZE
66	select ARCH_HAS_FAST_MULTIPLIER
67	select ARCH_HAS_FILTER_PGPROT
68	select ARCH_HAS_FORTIFY_SOURCE
69	select ARCH_HAS_GCOV_PROFILE_ALL
70	select ARCH_HAS_KCOV			if X86_64
71	select ARCH_HAS_MEM_ENCRYPT
72	select ARCH_HAS_MEMBARRIER_SYNC_CORE
73	select ARCH_HAS_PMEM_API		if X86_64
74	select ARCH_HAS_PTE_DEVMAP		if X86_64
75	select ARCH_HAS_PTE_SPECIAL
76	select ARCH_HAS_REFCOUNT
77	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64
78	select ARCH_HAS_UACCESS_MCSAFE		if X86_64 && X86_MCE
79	select ARCH_HAS_SET_MEMORY
80	select ARCH_HAS_SET_DIRECT_MAP
81	select ARCH_HAS_STRICT_KERNEL_RWX
82	select ARCH_HAS_STRICT_MODULE_RWX
83	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
84	select ARCH_HAS_UBSAN_SANITIZE_ALL
85	select ARCH_HAVE_NMI_SAFE_CMPXCHG
86	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
87	select ARCH_MIGHT_HAVE_PC_PARPORT
88	select ARCH_MIGHT_HAVE_PC_SERIO
89	select ARCH_STACKWALK
90	select ARCH_SUPPORTS_ACPI
91	select ARCH_SUPPORTS_ATOMIC_RMW
92	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
93	select ARCH_USE_BUILTIN_BSWAP
94	select ARCH_USE_QUEUED_RWLOCKS
95	select ARCH_USE_QUEUED_SPINLOCKS
96	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
97	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
98	select ARCH_WANT_HUGE_PMD_SHARE
99	select ARCH_WANTS_THP_SWAP		if X86_64
100	select BUILDTIME_EXTABLE_SORT
101	select CLKEVT_I8253
102	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
103	select CLOCKSOURCE_WATCHDOG
104	select DCACHE_WORD_ACCESS
105	select EDAC_ATOMIC_SCRUB
106	select EDAC_SUPPORT
107	select GENERIC_CLOCKEVENTS
108	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
109	select GENERIC_CLOCKEVENTS_MIN_ADJUST
110	select GENERIC_CMOS_UPDATE
111	select GENERIC_CPU_AUTOPROBE
112	select GENERIC_CPU_VULNERABILITIES
113	select GENERIC_EARLY_IOREMAP
114	select GENERIC_FIND_FIRST_BIT
115	select GENERIC_IOMAP
116	select GENERIC_IRQ_EFFECTIVE_AFF_MASK	if SMP
117	select GENERIC_IRQ_MATRIX_ALLOCATOR	if X86_LOCAL_APIC
118	select GENERIC_IRQ_MIGRATION		if SMP
119	select GENERIC_IRQ_PROBE
120	select GENERIC_IRQ_RESERVATION_MODE
121	select GENERIC_IRQ_SHOW
122	select GENERIC_PENDING_IRQ		if SMP
123	select GENERIC_SMP_IDLE_THREAD
124	select GENERIC_STRNCPY_FROM_USER
125	select GENERIC_STRNLEN_USER
126	select GENERIC_TIME_VSYSCALL
127	select GENERIC_GETTIMEOFDAY
128	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
129	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
130	select HAVE_ACPI_APEI			if ACPI
131	select HAVE_ACPI_APEI_NMI		if ACPI
132	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
133	select HAVE_ARCH_AUDITSYSCALL
134	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
135	select HAVE_ARCH_JUMP_LABEL
136	select HAVE_ARCH_JUMP_LABEL_RELATIVE
137	select HAVE_ARCH_KASAN			if X86_64
138	select HAVE_ARCH_KGDB
139	select HAVE_ARCH_MMAP_RND_BITS		if MMU
140	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
141	select HAVE_ARCH_COMPAT_MMAP_BASES	if MMU && COMPAT
142	select HAVE_ARCH_PREL32_RELOCATIONS
143	select HAVE_ARCH_SECCOMP_FILTER
144	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
145	select HAVE_ARCH_STACKLEAK
146	select HAVE_ARCH_TRACEHOOK
147	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
148	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
149	select HAVE_ARCH_VMAP_STACK		if X86_64
150	select HAVE_ARCH_WITHIN_STACK_FRAMES
151	select HAVE_ASM_MODVERSIONS
152	select HAVE_CMPXCHG_DOUBLE
153	select HAVE_CMPXCHG_LOCAL
154	select HAVE_CONTEXT_TRACKING		if X86_64
155	select HAVE_COPY_THREAD_TLS
156	select HAVE_C_RECORDMCOUNT
157	select HAVE_DEBUG_KMEMLEAK
158	select HAVE_DMA_CONTIGUOUS
159	select HAVE_DYNAMIC_FTRACE
160	select HAVE_DYNAMIC_FTRACE_WITH_REGS
161	select HAVE_EBPF_JIT
162	select HAVE_EFFICIENT_UNALIGNED_ACCESS
163	select HAVE_EISA
164	select HAVE_EXIT_THREAD
165	select HAVE_FAST_GUP
166	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
167	select HAVE_FTRACE_MCOUNT_RECORD
168	select HAVE_FUNCTION_GRAPH_TRACER
169	select HAVE_FUNCTION_TRACER
170	select HAVE_GCC_PLUGINS
171	select HAVE_HW_BREAKPOINT
172	select HAVE_IDE
173	select HAVE_IOREMAP_PROT
174	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
175	select HAVE_IRQ_TIME_ACCOUNTING
176	select HAVE_KERNEL_BZIP2
177	select HAVE_KERNEL_GZIP
178	select HAVE_KERNEL_LZ4
179	select HAVE_KERNEL_LZMA
180	select HAVE_KERNEL_LZO
181	select HAVE_KERNEL_XZ
182	select HAVE_KPROBES
183	select HAVE_KPROBES_ON_FTRACE
184	select HAVE_FUNCTION_ERROR_INJECTION
185	select HAVE_KRETPROBES
186	select HAVE_KVM
187	select HAVE_LIVEPATCH			if X86_64
188	select HAVE_MEMBLOCK_NODE_MAP
189	select HAVE_MIXED_BREAKPOINTS_REGS
190	select HAVE_MOD_ARCH_SPECIFIC
191	select HAVE_MOVE_PMD
192	select HAVE_NMI
193	select HAVE_OPROFILE
194	select HAVE_OPTPROBES
195	select HAVE_PCSPKR_PLATFORM
196	select HAVE_PERF_EVENTS
197	select HAVE_PERF_EVENTS_NMI
198	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
199	select HAVE_PCI
200	select HAVE_PERF_REGS
201	select HAVE_PERF_USER_STACK_DUMP
202	select HAVE_RCU_TABLE_FREE		if PARAVIRT
203	select HAVE_REGS_AND_STACK_ACCESS_API
204	select HAVE_RELIABLE_STACKTRACE		if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
205	select HAVE_FUNCTION_ARG_ACCESS_API
206	select HAVE_STACKPROTECTOR		if CC_HAS_SANE_STACKPROTECTOR
207	select HAVE_STACK_VALIDATION		if X86_64
208	select HAVE_RSEQ
209	select HAVE_SYSCALL_TRACEPOINTS
210	select HAVE_UNSTABLE_SCHED_CLOCK
211	select HAVE_USER_RETURN_NOTIFIER
212	select HAVE_GENERIC_VDSO
213	select HOTPLUG_SMT			if SMP
214	select IRQ_FORCED_THREADING
215	select NEED_SG_DMA_LENGTH
216	select PCI_DOMAINS			if PCI
217	select PCI_LOCKLESS_CONFIG		if PCI
218	select PERF_EVENTS
219	select RTC_LIB
220	select RTC_MC146818_LIB
221	select SPARSE_IRQ
222	select SRCU
223	select SYSCTL_EXCEPTION_TRACE
224	select THREAD_INFO_IN_TASK
225	select USER_STACKTRACE_SUPPORT
226	select VIRT_TO_BUS
227	select X86_FEATURE_NAMES		if PROC_FS
228	select PROC_PID_ARCH_STATUS		if PROC_FS
229
230config INSTRUCTION_DECODER
231	def_bool y
232	depends on KPROBES || PERF_EVENTS || UPROBES
233
234config OUTPUT_FORMAT
235	string
236	default "elf32-i386" if X86_32
237	default "elf64-x86-64" if X86_64
238
239config ARCH_DEFCONFIG
240	string
241	default "arch/x86/configs/i386_defconfig" if X86_32
242	default "arch/x86/configs/x86_64_defconfig" if X86_64
243
244config LOCKDEP_SUPPORT
245	def_bool y
246
247config STACKTRACE_SUPPORT
248	def_bool y
249
250config MMU
251	def_bool y
252
253config ARCH_MMAP_RND_BITS_MIN
254	default 28 if 64BIT
255	default 8
256
257config ARCH_MMAP_RND_BITS_MAX
258	default 32 if 64BIT
259	default 16
260
261config ARCH_MMAP_RND_COMPAT_BITS_MIN
262	default 8
263
264config ARCH_MMAP_RND_COMPAT_BITS_MAX
265	default 16
266
267config SBUS
268	bool
269
270config GENERIC_ISA_DMA
271	def_bool y
272	depends on ISA_DMA_API
273
274config GENERIC_BUG
275	def_bool y
276	depends on BUG
277	select GENERIC_BUG_RELATIVE_POINTERS if X86_64
278
279config GENERIC_BUG_RELATIVE_POINTERS
280	bool
281
282config ARCH_MAY_HAVE_PC_FDC
283	def_bool y
284	depends on ISA_DMA_API
285
286config GENERIC_CALIBRATE_DELAY
287	def_bool y
288
289config ARCH_HAS_CPU_RELAX
290	def_bool y
291
292config ARCH_HAS_CACHE_LINE_SIZE
293	def_bool y
294
295config ARCH_HAS_FILTER_PGPROT
296	def_bool y
297
298config HAVE_SETUP_PER_CPU_AREA
299	def_bool y
300
301config NEED_PER_CPU_EMBED_FIRST_CHUNK
302	def_bool y
303
304config NEED_PER_CPU_PAGE_FIRST_CHUNK
305	def_bool y
306
307config ARCH_HIBERNATION_POSSIBLE
308	def_bool y
309
310config ARCH_SUSPEND_POSSIBLE
311	def_bool y
312
313config ARCH_WANT_GENERAL_HUGETLB
314	def_bool y
315
316config ZONE_DMA32
317	def_bool y if X86_64
318
319config AUDIT_ARCH
320	def_bool y if X86_64
321
322config ARCH_SUPPORTS_DEBUG_PAGEALLOC
323	def_bool y
324
325config KASAN_SHADOW_OFFSET
326	hex
327	depends on KASAN
328	default 0xdffffc0000000000
329
330config HAVE_INTEL_TXT
331	def_bool y
332	depends on INTEL_IOMMU && ACPI
333
334config X86_32_SMP
335	def_bool y
336	depends on X86_32 && SMP
337
338config X86_64_SMP
339	def_bool y
340	depends on X86_64 && SMP
341
342config X86_32_LAZY_GS
343	def_bool y
344	depends on X86_32 && !STACKPROTECTOR
345
346config ARCH_SUPPORTS_UPROBES
347	def_bool y
348
349config FIX_EARLYCON_MEM
350	def_bool y
351
352config DYNAMIC_PHYSICAL_MASK
353	bool
354
355config PGTABLE_LEVELS
356	int
357	default 5 if X86_5LEVEL
358	default 4 if X86_64
359	default 3 if X86_PAE
360	default 2
361
362config CC_HAS_SANE_STACKPROTECTOR
363	bool
364	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
365	default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
366	help
367	   We have to make sure stack protector is unconditionally disabled if
368	   the compiler produces broken code.
369
370menu "Processor type and features"
371
372config ZONE_DMA
373	bool "DMA memory allocation support" if EXPERT
374	default y
375	help
376	  DMA memory allocation support allows devices with less than 32-bit
377	  addressing to allocate within the first 16MB of address space.
378	  Disable if no such devices will be used.
379
380	  If unsure, say Y.
381
382config SMP
383	bool "Symmetric multi-processing support"
384	---help---
385	  This enables support for systems with more than one CPU. If you have
386	  a system with only one CPU, say N. If you have a system with more
387	  than one CPU, say Y.
388
389	  If you say N here, the kernel will run on uni- and multiprocessor
390	  machines, but will use only one CPU of a multiprocessor machine. If
391	  you say Y here, the kernel will run on many, but not all,
392	  uniprocessor machines. On a uniprocessor machine, the kernel
393	  will run faster if you say N here.
394
395	  Note that if you say Y here and choose architecture "586" or
396	  "Pentium" under "Processor family", the kernel will not work on 486
397	  architectures. Similarly, multiprocessor kernels for the "PPro"
398	  architecture may not work on all Pentium based boards.
399
400	  People using multiprocessor machines who say Y here should also say
401	  Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
402	  Management" code will be disabled if you say Y here.
403
404	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
405	  <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
406	  <http://www.tldp.org/docs.html#howto>.
407
408	  If you don't know what to do here, say N.
409
410config X86_FEATURE_NAMES
411	bool "Processor feature human-readable names" if EMBEDDED
412	default y
413	---help---
414	  This option compiles in a table of x86 feature bits and corresponding
415	  names.  This is required to support /proc/cpuinfo and a few kernel
416	  messages.  You can disable this to save space, at the expense of
417	  making those few kernel messages show numeric feature bits instead.
418
419	  If in doubt, say Y.
420
421config X86_X2APIC
422	bool "Support x2apic"
423	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
424	---help---
425	  This enables x2apic support on CPUs that have this feature.
426
427	  This allows 32-bit apic IDs (so it can support very large systems),
428	  and accesses the local apic via MSRs not via mmio.
429
430	  If you don't know what to do here, say N.
431
432config X86_MPPARSE
433	bool "Enable MPS table" if ACPI || SFI
434	default y
435	depends on X86_LOCAL_APIC
436	---help---
437	  For old smp systems that do not have proper acpi support. Newer systems
438	  (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
439
440config GOLDFISH
441       def_bool y
442       depends on X86_GOLDFISH
443
444config RETPOLINE
445	bool "Avoid speculative indirect branches in kernel"
446	default y
447	select STACK_VALIDATION if HAVE_STACK_VALIDATION
448	help
449	  Compile kernel with the retpoline compiler options to guard against
450	  kernel-to-user data leaks by avoiding speculative indirect
451	  branches. Requires a compiler with -mindirect-branch=thunk-extern
452	  support for full protection. The kernel may run slower.
453
454config X86_CPU_RESCTRL
455	bool "x86 CPU resource control support"
456	depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
457	select KERNFS
458	help
459	  Enable x86 CPU resource control support.
460
461	  Provide support for the allocation and monitoring of system resources
462	  usage by the CPU.
463
464	  Intel calls this Intel Resource Director Technology
465	  (Intel(R) RDT). More information about RDT can be found in the
466	  Intel x86 Architecture Software Developer Manual.
467
468	  AMD calls this AMD Platform Quality of Service (AMD QoS).
469	  More information about AMD QoS can be found in the AMD64 Technology
470	  Platform Quality of Service Extensions manual.
471
472	  Say N if unsure.
473
474if X86_32
475config X86_BIGSMP
476	bool "Support for big SMP systems with more than 8 CPUs"
477	depends on SMP
478	---help---
479	  This option is needed for the systems that have more than 8 CPUs
480
481config X86_EXTENDED_PLATFORM
482	bool "Support for extended (non-PC) x86 platforms"
483	default y
484	---help---
485	  If you disable this option then the kernel will only support
486	  standard PC platforms. (which covers the vast majority of
487	  systems out there.)
488
489	  If you enable this option then you'll be able to select support
490	  for the following (non-PC) 32 bit x86 platforms:
491		Goldfish (Android emulator)
492		AMD Elan
493		RDC R-321x SoC
494		SGI 320/540 (Visual Workstation)
495		STA2X11-based (e.g. Northville)
496		Moorestown MID devices
497
498	  If you have one of these systems, or if you want to build a
499	  generic distribution kernel, say Y here - otherwise say N.
500endif
501
502if X86_64
503config X86_EXTENDED_PLATFORM
504	bool "Support for extended (non-PC) x86 platforms"
505	default y
506	---help---
507	  If you disable this option then the kernel will only support
508	  standard PC platforms. (which covers the vast majority of
509	  systems out there.)
510
511	  If you enable this option then you'll be able to select support
512	  for the following (non-PC) 64 bit x86 platforms:
513		Numascale NumaChip
514		ScaleMP vSMP
515		SGI Ultraviolet
516
517	  If you have one of these systems, or if you want to build a
518	  generic distribution kernel, say Y here - otherwise say N.
519endif
520# This is an alphabetically sorted list of 64 bit extended platforms
521# Please maintain the alphabetic order if and when there are additions
522config X86_NUMACHIP
523	bool "Numascale NumaChip"
524	depends on X86_64
525	depends on X86_EXTENDED_PLATFORM
526	depends on NUMA
527	depends on SMP
528	depends on X86_X2APIC
529	depends on PCI_MMCONFIG
530	---help---
531	  Adds support for Numascale NumaChip large-SMP systems. Needed to
532	  enable more than ~168 cores.
533	  If you don't have one of these, you should say N here.
534
535config X86_VSMP
536	bool "ScaleMP vSMP"
537	select HYPERVISOR_GUEST
538	select PARAVIRT
539	depends on X86_64 && PCI
540	depends on X86_EXTENDED_PLATFORM
541	depends on SMP
542	---help---
543	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is
544	  supposed to run on these EM64T-based machines.  Only choose this option
545	  if you have one of these machines.
546
547config X86_UV
548	bool "SGI Ultraviolet"
549	depends on X86_64
550	depends on X86_EXTENDED_PLATFORM
551	depends on NUMA
552	depends on EFI
553	depends on X86_X2APIC
554	depends on PCI
555	---help---
556	  This option is needed in order to support SGI Ultraviolet systems.
557	  If you don't have one of these, you should say N here.
558
559# Following is an alphabetically sorted list of 32 bit extended platforms
560# Please maintain the alphabetic order if and when there are additions
561
562config X86_GOLDFISH
563       bool "Goldfish (Virtual Platform)"
564       depends on X86_EXTENDED_PLATFORM
565       ---help---
566	 Enable support for the Goldfish virtual platform used primarily
567	 for Android development. Unless you are building for the Android
568	 Goldfish emulator say N here.
569
570config X86_INTEL_CE
571	bool "CE4100 TV platform"
572	depends on PCI
573	depends on PCI_GODIRECT
574	depends on X86_IO_APIC
575	depends on X86_32
576	depends on X86_EXTENDED_PLATFORM
577	select X86_REBOOTFIXUPS
578	select OF
579	select OF_EARLY_FLATTREE
580	---help---
581	  Select for the Intel CE media processor (CE4100) SOC.
582	  This option compiles in support for the CE4100 SOC for settop
583	  boxes and media devices.
584
585config X86_INTEL_MID
586	bool "Intel MID platform support"
587	depends on X86_EXTENDED_PLATFORM
588	depends on X86_PLATFORM_DEVICES
589	depends on PCI
590	depends on X86_64 || (PCI_GOANY && X86_32)
591	depends on X86_IO_APIC
592	select SFI
593	select I2C
594	select DW_APB_TIMER
595	select APB_TIMER
596	select INTEL_SCU_IPC
597	select MFD_INTEL_MSIC
598	---help---
599	  Select to build a kernel capable of supporting Intel MID (Mobile
600	  Internet Device) platform systems which do not have the PCI legacy
601	  interfaces. If you are building for a PC class system say N here.
602
603	  Intel MID platforms are based on an Intel processor and chipset which
604	  consume less power than most of the x86 derivatives.
605
606config X86_INTEL_QUARK
607	bool "Intel Quark platform support"
608	depends on X86_32
609	depends on X86_EXTENDED_PLATFORM
610	depends on X86_PLATFORM_DEVICES
611	depends on X86_TSC
612	depends on PCI
613	depends on PCI_GOANY
614	depends on X86_IO_APIC
615	select IOSF_MBI
616	select INTEL_IMR
617	select COMMON_CLK
618	---help---
619	  Select to include support for Quark X1000 SoC.
620	  Say Y here if you have a Quark based system such as the Arduino
621	  compatible Intel Galileo.
622
623config X86_INTEL_LPSS
624	bool "Intel Low Power Subsystem Support"
625	depends on X86 && ACPI && PCI
626	select COMMON_CLK
627	select PINCTRL
628	select IOSF_MBI
629	---help---
630	  Select to build support for Intel Low Power Subsystem such as
631	  found on Intel Lynxpoint PCH. Selecting this option enables
632	  things like clock tree (common clock framework) and pincontrol
633	  which are needed by the LPSS peripheral drivers.
634
635config X86_AMD_PLATFORM_DEVICE
636	bool "AMD ACPI2Platform devices support"
637	depends on ACPI
638	select COMMON_CLK
639	select PINCTRL
640	---help---
641	  Select to interpret AMD specific ACPI device to platform device
642	  such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
643	  I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
644	  implemented under PINCTRL subsystem.
645
646config IOSF_MBI
647	tristate "Intel SoC IOSF Sideband support for SoC platforms"
648	depends on PCI
649	---help---
650	  This option enables sideband register access support for Intel SoC
651	  platforms. On these platforms the IOSF sideband is used in lieu of
652	  MSR's for some register accesses, mostly but not limited to thermal
653	  and power. Drivers may query the availability of this device to
654	  determine if they need the sideband in order to work on these
655	  platforms. The sideband is available on the following SoC products.
656	  This list is not meant to be exclusive.
657	   - BayTrail
658	   - Braswell
659	   - Quark
660
661	  You should say Y if you are running a kernel on one of these SoC's.
662
663config IOSF_MBI_DEBUG
664	bool "Enable IOSF sideband access through debugfs"
665	depends on IOSF_MBI && DEBUG_FS
666	---help---
667	  Select this option to expose the IOSF sideband access registers (MCR,
668	  MDR, MCRX) through debugfs to write and read register information from
669	  different units on the SoC. This is most useful for obtaining device
670	  state information for debug and analysis. As this is a general access
671	  mechanism, users of this option would have specific knowledge of the
672	  device they want to access.
673
674	  If you don't require the option or are in doubt, say N.
675
676config X86_RDC321X
677	bool "RDC R-321x SoC"
678	depends on X86_32
679	depends on X86_EXTENDED_PLATFORM
680	select M486
681	select X86_REBOOTFIXUPS
682	---help---
683	  This option is needed for RDC R-321x system-on-chip, also known
684	  as R-8610-(G).
685	  If you don't have one of these chips, you should say N here.
686
687config X86_32_NON_STANDARD
688	bool "Support non-standard 32-bit SMP architectures"
689	depends on X86_32 && SMP
690	depends on X86_EXTENDED_PLATFORM
691	---help---
692	  This option compiles in the bigsmp and STA2X11 default
693	  subarchitectures.  It is intended for a generic binary
694	  kernel. If you select them all, kernel will probe it one by
695	  one and will fallback to default.
696
697# Alphabetically sorted list of Non standard 32 bit platforms
698
699config X86_SUPPORTS_MEMORY_FAILURE
700	def_bool y
701	# MCE code calls memory_failure():
702	depends on X86_MCE
703	# On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
704	# On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
705	depends on X86_64 || !SPARSEMEM
706	select ARCH_SUPPORTS_MEMORY_FAILURE
707
708config STA2X11
709	bool "STA2X11 Companion Chip Support"
710	depends on X86_32_NON_STANDARD && PCI
711	select ARCH_HAS_PHYS_TO_DMA
712	select SWIOTLB
713	select MFD_STA2X11
714	select GPIOLIB
715	---help---
716	  This adds support for boards based on the STA2X11 IO-Hub,
717	  a.k.a. "ConneXt". The chip is used in place of the standard
718	  PC chipset, so all "standard" peripherals are missing. If this
719	  option is selected the kernel will still be able to boot on
720	  standard PC machines.
721
722config X86_32_IRIS
723	tristate "Eurobraille/Iris poweroff module"
724	depends on X86_32
725	---help---
726	  The Iris machines from EuroBraille do not have APM or ACPI support
727	  to shut themselves down properly.  A special I/O sequence is
728	  needed to do so, which is what this module does at
729	  kernel shutdown.
730
731	  This is only for Iris machines from EuroBraille.
732
733	  If unused, say N.
734
735config SCHED_OMIT_FRAME_POINTER
736	def_bool y
737	prompt "Single-depth WCHAN output"
738	depends on X86
739	---help---
740	  Calculate simpler /proc/<PID>/wchan values. If this option
741	  is disabled then wchan values will recurse back to the
742	  caller function. This provides more accurate wchan values,
743	  at the expense of slightly more scheduling overhead.
744
745	  If in doubt, say "Y".
746
747menuconfig HYPERVISOR_GUEST
748	bool "Linux guest support"
749	---help---
750	  Say Y here to enable options for running Linux under various hyper-
751	  visors. This option enables basic hypervisor detection and platform
752	  setup.
753
754	  If you say N, all options in this submenu will be skipped and
755	  disabled, and Linux guest support won't be built in.
756
757if HYPERVISOR_GUEST
758
759config PARAVIRT
760	bool "Enable paravirtualization code"
761	---help---
762	  This changes the kernel so it can modify itself when it is run
763	  under a hypervisor, potentially improving performance significantly
764	  over full virtualization.  However, when run without a hypervisor
765	  the kernel is theoretically slower and slightly larger.
766
767config PARAVIRT_XXL
768	bool
769
770config PARAVIRT_DEBUG
771	bool "paravirt-ops debugging"
772	depends on PARAVIRT && DEBUG_KERNEL
773	---help---
774	  Enable to debug paravirt_ops internals.  Specifically, BUG if
775	  a paravirt_op is missing when it is called.
776
777config PARAVIRT_SPINLOCKS
778	bool "Paravirtualization layer for spinlocks"
779	depends on PARAVIRT && SMP
780	---help---
781	  Paravirtualized spinlocks allow a pvops backend to replace the
782	  spinlock implementation with something virtualization-friendly
783	  (for example, block the virtual CPU rather than spinning).
784
785	  It has a minimal impact on native kernels and gives a nice performance
786	  benefit on paravirtualized KVM / Xen kernels.
787
788	  If you are unsure how to answer this question, answer Y.
789
790config X86_HV_CALLBACK_VECTOR
791	def_bool n
792
793source "arch/x86/xen/Kconfig"
794
795config KVM_GUEST
796	bool "KVM Guest support (including kvmclock)"
797	depends on PARAVIRT
798	select PARAVIRT_CLOCK
799	select ARCH_CPUIDLE_HALTPOLL
800	default y
801	---help---
802	  This option enables various optimizations for running under the KVM
803	  hypervisor. It includes a paravirtualized clock, so that instead
804	  of relying on a PIT (or probably other) emulation by the
805	  underlying device model, the host provides the guest with
806	  timing infrastructure such as time of day, and system time
807
808config ARCH_CPUIDLE_HALTPOLL
809        def_bool n
810        prompt "Disable host haltpoll when loading haltpoll driver"
811        help
812	  If virtualized under KVM, disable host haltpoll.
813
814config PVH
815	bool "Support for running PVH guests"
816	---help---
817	  This option enables the PVH entry point for guest virtual machines
818	  as specified in the x86/HVM direct boot ABI.
819
820config KVM_DEBUG_FS
821	bool "Enable debug information for KVM Guests in debugfs"
822	depends on KVM_GUEST && DEBUG_FS
823	---help---
824	  This option enables collection of various statistics for KVM guest.
825	  Statistics are displayed in debugfs filesystem. Enabling this option
826	  may incur significant overhead.
827
828config PARAVIRT_TIME_ACCOUNTING
829	bool "Paravirtual steal time accounting"
830	depends on PARAVIRT
831	---help---
832	  Select this option to enable fine granularity task steal time
833	  accounting. Time spent executing other tasks in parallel with
834	  the current vCPU is discounted from the vCPU power. To account for
835	  that, there can be a small performance impact.
836
837	  If in doubt, say N here.
838
839config PARAVIRT_CLOCK
840	bool
841
842config JAILHOUSE_GUEST
843	bool "Jailhouse non-root cell support"
844	depends on X86_64 && PCI
845	select X86_PM_TIMER
846	---help---
847	  This option allows to run Linux as guest in a Jailhouse non-root
848	  cell. You can leave this option disabled if you only want to start
849	  Jailhouse and run Linux afterwards in the root cell.
850
851config ACRN_GUEST
852	bool "ACRN Guest support"
853	depends on X86_64
854	select X86_HV_CALLBACK_VECTOR
855	help
856	  This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
857	  a flexible, lightweight reference open-source hypervisor, built with
858	  real-time and safety-criticality in mind. It is built for embedded
859	  IOT with small footprint and real-time features. More details can be
860	  found in https://projectacrn.org/.
861
862endif #HYPERVISOR_GUEST
863
864source "arch/x86/Kconfig.cpu"
865
866config HPET_TIMER
867	def_bool X86_64
868	prompt "HPET Timer Support" if X86_32
869	---help---
870	  Use the IA-PC HPET (High Precision Event Timer) to manage
871	  time in preference to the PIT and RTC, if a HPET is
872	  present.
873	  HPET is the next generation timer replacing legacy 8254s.
874	  The HPET provides a stable time base on SMP
875	  systems, unlike the TSC, but it is more expensive to access,
876	  as it is off-chip.  The interface used is documented
877	  in the HPET spec, revision 1.
878
879	  You can safely choose Y here.  However, HPET will only be
880	  activated if the platform and the BIOS support this feature.
881	  Otherwise the 8254 will be used for timing services.
882
883	  Choose N to continue using the legacy 8254 timer.
884
885config HPET_EMULATE_RTC
886	def_bool y
887	depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
888
889config APB_TIMER
890       def_bool y if X86_INTEL_MID
891       prompt "Intel MID APB Timer Support" if X86_INTEL_MID
892       select DW_APB_TIMER
893       depends on X86_INTEL_MID && SFI
894       help
895         APB timer is the replacement for 8254, HPET on X86 MID platforms.
896         The APBT provides a stable time base on SMP
897         systems, unlike the TSC, but it is more expensive to access,
898         as it is off-chip. APB timers are always running regardless of CPU
899         C states, they are used as per CPU clockevent device when possible.
900
901# Mark as expert because too many people got it wrong.
902# The code disables itself when not needed.
903config DMI
904	default y
905	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
906	bool "Enable DMI scanning" if EXPERT
907	---help---
908	  Enabled scanning of DMI to identify machine quirks. Say Y
909	  here unless you have verified that your setup is not
910	  affected by entries in the DMI blacklist. Required by PNP
911	  BIOS code.
912
913config GART_IOMMU
914	bool "Old AMD GART IOMMU support"
915	select IOMMU_HELPER
916	select SWIOTLB
917	depends on X86_64 && PCI && AMD_NB
918	---help---
919	  Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
920	  GART based hardware IOMMUs.
921
922	  The GART supports full DMA access for devices with 32-bit access
923	  limitations, on systems with more than 3 GB. This is usually needed
924	  for USB, sound, many IDE/SATA chipsets and some other devices.
925
926	  Newer systems typically have a modern AMD IOMMU, supported via
927	  the CONFIG_AMD_IOMMU=y config option.
928
929	  In normal configurations this driver is only active when needed:
930	  there's more than 3 GB of memory and the system contains a
931	  32-bit limited device.
932
933	  If unsure, say Y.
934
935config CALGARY_IOMMU
936	bool "IBM Calgary IOMMU support"
937	select IOMMU_HELPER
938	select SWIOTLB
939	depends on X86_64 && PCI
940	---help---
941	  Support for hardware IOMMUs in IBM's xSeries x366 and x460
942	  systems. Needed to run systems with more than 3GB of memory
943	  properly with 32-bit PCI devices that do not support DAC
944	  (Double Address Cycle). Calgary also supports bus level
945	  isolation, where all DMAs pass through the IOMMU.  This
946	  prevents them from going anywhere except their intended
947	  destination. This catches hard-to-find kernel bugs and
948	  mis-behaving drivers and devices that do not use the DMA-API
949	  properly to set up their DMA buffers.  The IOMMU can be
950	  turned off at boot time with the iommu=off parameter.
951	  Normally the kernel will make the right choice by itself.
952	  If unsure, say Y.
953
954config CALGARY_IOMMU_ENABLED_BY_DEFAULT
955	def_bool y
956	prompt "Should Calgary be enabled by default?"
957	depends on CALGARY_IOMMU
958	---help---
959	  Should Calgary be enabled by default? if you choose 'y', Calgary
960	  will be used (if it exists). If you choose 'n', Calgary will not be
961	  used even if it exists. If you choose 'n' and would like to use
962	  Calgary anyway, pass 'iommu=calgary' on the kernel command line.
963	  If unsure, say Y.
964
965config MAXSMP
966	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
967	depends on X86_64 && SMP && DEBUG_KERNEL
968	select CPUMASK_OFFSTACK
969	---help---
970	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
971	  If unsure, say N.
972
973#
974# The maximum number of CPUs supported:
975#
976# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
977# and which can be configured interactively in the
978# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
979#
980# The ranges are different on 32-bit and 64-bit kernels, depending on
981# hardware capabilities and scalability features of the kernel.
982#
983# ( If MAXSMP is enabled we just use the highest possible value and disable
984#   interactive configuration. )
985#
986
987config NR_CPUS_RANGE_BEGIN
988	int
989	default NR_CPUS_RANGE_END if MAXSMP
990	default    1 if !SMP
991	default    2
992
993config NR_CPUS_RANGE_END
994	int
995	depends on X86_32
996	default   64 if  SMP &&  X86_BIGSMP
997	default    8 if  SMP && !X86_BIGSMP
998	default    1 if !SMP
999
1000config NR_CPUS_RANGE_END
1001	int
1002	depends on X86_64
1003	default 8192 if  SMP && ( MAXSMP ||  CPUMASK_OFFSTACK)
1004	default  512 if  SMP && (!MAXSMP && !CPUMASK_OFFSTACK)
1005	default    1 if !SMP
1006
1007config NR_CPUS_DEFAULT
1008	int
1009	depends on X86_32
1010	default   32 if  X86_BIGSMP
1011	default    8 if  SMP
1012	default    1 if !SMP
1013
1014config NR_CPUS_DEFAULT
1015	int
1016	depends on X86_64
1017	default 8192 if  MAXSMP
1018	default   64 if  SMP
1019	default    1 if !SMP
1020
1021config NR_CPUS
1022	int "Maximum number of CPUs" if SMP && !MAXSMP
1023	range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1024	default NR_CPUS_DEFAULT
1025	---help---
1026	  This allows you to specify the maximum number of CPUs which this
1027	  kernel will support.  If CPUMASK_OFFSTACK is enabled, the maximum
1028	  supported value is 8192, otherwise the maximum value is 512.  The
1029	  minimum value which makes sense is 2.
1030
1031	  This is purely to save memory: each supported CPU adds about 8KB
1032	  to the kernel image.
1033
1034config SCHED_SMT
1035	def_bool y if SMP
1036
1037config SCHED_MC
1038	def_bool y
1039	prompt "Multi-core scheduler support"
1040	depends on SMP
1041	---help---
1042	  Multi-core scheduler support improves the CPU scheduler's decision
1043	  making when dealing with multi-core CPU chips at a cost of slightly
1044	  increased overhead in some places. If unsure say N here.
1045
1046config SCHED_MC_PRIO
1047	bool "CPU core priorities scheduler support"
1048	depends on SCHED_MC && CPU_SUP_INTEL
1049	select X86_INTEL_PSTATE
1050	select CPU_FREQ
1051	default y
1052	---help---
1053	  Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1054	  core ordering determined at manufacturing time, which allows
1055	  certain cores to reach higher turbo frequencies (when running
1056	  single threaded workloads) than others.
1057
1058	  Enabling this kernel feature teaches the scheduler about
1059	  the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1060	  scheduler's CPU selection logic accordingly, so that higher
1061	  overall system performance can be achieved.
1062
1063	  This feature will have no effect on CPUs without this feature.
1064
1065	  If unsure say Y here.
1066
1067config UP_LATE_INIT
1068       def_bool y
1069       depends on !SMP && X86_LOCAL_APIC
1070
1071config X86_UP_APIC
1072	bool "Local APIC support on uniprocessors" if !PCI_MSI
1073	default PCI_MSI
1074	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1075	---help---
1076	  A local APIC (Advanced Programmable Interrupt Controller) is an
1077	  integrated interrupt controller in the CPU. If you have a single-CPU
1078	  system which has a processor with a local APIC, you can say Y here to
1079	  enable and use it. If you say Y here even though your machine doesn't
1080	  have a local APIC, then the kernel will still run with no slowdown at
1081	  all. The local APIC supports CPU-generated self-interrupts (timer,
1082	  performance counters), and the NMI watchdog which detects hard
1083	  lockups.
1084
1085config X86_UP_IOAPIC
1086	bool "IO-APIC support on uniprocessors"
1087	depends on X86_UP_APIC
1088	---help---
1089	  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1090	  SMP-capable replacement for PC-style interrupt controllers. Most
1091	  SMP systems and many recent uniprocessor systems have one.
1092
1093	  If you have a single-CPU system with an IO-APIC, you can say Y here
1094	  to use it. If you say Y here even though your machine doesn't have
1095	  an IO-APIC, then the kernel will still run with no slowdown at all.
1096
1097config X86_LOCAL_APIC
1098	def_bool y
1099	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1100	select IRQ_DOMAIN_HIERARCHY
1101	select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1102
1103config X86_IO_APIC
1104	def_bool y
1105	depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1106
1107config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1108	bool "Reroute for broken boot IRQs"
1109	depends on X86_IO_APIC
1110	---help---
1111	  This option enables a workaround that fixes a source of
1112	  spurious interrupts. This is recommended when threaded
1113	  interrupt handling is used on systems where the generation of
1114	  superfluous "boot interrupts" cannot be disabled.
1115
1116	  Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1117	  entry in the chipset's IO-APIC is masked (as, e.g. the RT
1118	  kernel does during interrupt handling). On chipsets where this
1119	  boot IRQ generation cannot be disabled, this workaround keeps
1120	  the original IRQ line masked so that only the equivalent "boot
1121	  IRQ" is delivered to the CPUs. The workaround also tells the
1122	  kernel to set up the IRQ handler on the boot IRQ line. In this
1123	  way only one interrupt is delivered to the kernel. Otherwise
1124	  the spurious second interrupt may cause the kernel to bring
1125	  down (vital) interrupt lines.
1126
1127	  Only affects "broken" chipsets. Interrupt sharing may be
1128	  increased on these systems.
1129
1130config X86_MCE
1131	bool "Machine Check / overheating reporting"
1132	select GENERIC_ALLOCATOR
1133	default y
1134	---help---
1135	  Machine Check support allows the processor to notify the
1136	  kernel if it detects a problem (e.g. overheating, data corruption).
1137	  The action the kernel takes depends on the severity of the problem,
1138	  ranging from warning messages to halting the machine.
1139
1140config X86_MCELOG_LEGACY
1141	bool "Support for deprecated /dev/mcelog character device"
1142	depends on X86_MCE
1143	---help---
1144	  Enable support for /dev/mcelog which is needed by the old mcelog
1145	  userspace logging daemon. Consider switching to the new generation
1146	  rasdaemon solution.
1147
1148config X86_MCE_INTEL
1149	def_bool y
1150	prompt "Intel MCE features"
1151	depends on X86_MCE && X86_LOCAL_APIC
1152	---help---
1153	   Additional support for intel specific MCE features such as
1154	   the thermal monitor.
1155
1156config X86_MCE_AMD
1157	def_bool y
1158	prompt "AMD MCE features"
1159	depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1160	---help---
1161	   Additional support for AMD specific MCE features such as
1162	   the DRAM Error Threshold.
1163
1164config X86_ANCIENT_MCE
1165	bool "Support for old Pentium 5 / WinChip machine checks"
1166	depends on X86_32 && X86_MCE
1167	---help---
1168	  Include support for machine check handling on old Pentium 5 or WinChip
1169	  systems. These typically need to be enabled explicitly on the command
1170	  line.
1171
1172config X86_MCE_THRESHOLD
1173	depends on X86_MCE_AMD || X86_MCE_INTEL
1174	def_bool y
1175
1176config X86_MCE_INJECT
1177	depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1178	tristate "Machine check injector support"
1179	---help---
1180	  Provide support for injecting machine checks for testing purposes.
1181	  If you don't know what a machine check is and you don't do kernel
1182	  QA it is safe to say n.
1183
1184config X86_THERMAL_VECTOR
1185	def_bool y
1186	depends on X86_MCE_INTEL
1187
1188source "arch/x86/events/Kconfig"
1189
1190config X86_LEGACY_VM86
1191	bool "Legacy VM86 support"
1192	depends on X86_32
1193	---help---
1194	  This option allows user programs to put the CPU into V8086
1195	  mode, which is an 80286-era approximation of 16-bit real mode.
1196
1197	  Some very old versions of X and/or vbetool require this option
1198	  for user mode setting.  Similarly, DOSEMU will use it if
1199	  available to accelerate real mode DOS programs.  However, any
1200	  recent version of DOSEMU, X, or vbetool should be fully
1201	  functional even without kernel VM86 support, as they will all
1202	  fall back to software emulation. Nevertheless, if you are using
1203	  a 16-bit DOS program where 16-bit performance matters, vm86
1204	  mode might be faster than emulation and you might want to
1205	  enable this option.
1206
1207	  Note that any app that works on a 64-bit kernel is unlikely to
1208	  need this option, as 64-bit kernels don't, and can't, support
1209	  V8086 mode. This option is also unrelated to 16-bit protected
1210	  mode and is not needed to run most 16-bit programs under Wine.
1211
1212	  Enabling this option increases the complexity of the kernel
1213	  and slows down exception handling a tiny bit.
1214
1215	  If unsure, say N here.
1216
1217config VM86
1218       bool
1219       default X86_LEGACY_VM86
1220
1221config X86_16BIT
1222	bool "Enable support for 16-bit segments" if EXPERT
1223	default y
1224	depends on MODIFY_LDT_SYSCALL
1225	---help---
1226	  This option is required by programs like Wine to run 16-bit
1227	  protected mode legacy code on x86 processors.  Disabling
1228	  this option saves about 300 bytes on i386, or around 6K text
1229	  plus 16K runtime memory on x86-64,
1230
1231config X86_ESPFIX32
1232	def_bool y
1233	depends on X86_16BIT && X86_32
1234
1235config X86_ESPFIX64
1236	def_bool y
1237	depends on X86_16BIT && X86_64
1238
1239config X86_VSYSCALL_EMULATION
1240       bool "Enable vsyscall emulation" if EXPERT
1241       default y
1242       depends on X86_64
1243       ---help---
1244	 This enables emulation of the legacy vsyscall page.  Disabling
1245	 it is roughly equivalent to booting with vsyscall=none, except
1246	 that it will also disable the helpful warning if a program
1247	 tries to use a vsyscall.  With this option set to N, offending
1248	 programs will just segfault, citing addresses of the form
1249	 0xffffffffff600?00.
1250
1251	 This option is required by many programs built before 2013, and
1252	 care should be used even with newer programs if set to N.
1253
1254	 Disabling this option saves about 7K of kernel size and
1255	 possibly 4K of additional runtime pagetable memory.
1256
1257config TOSHIBA
1258	tristate "Toshiba Laptop support"
1259	depends on X86_32
1260	---help---
1261	  This adds a driver to safely access the System Management Mode of
1262	  the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1263	  not work on models with a Phoenix BIOS. The System Management Mode
1264	  is used to set the BIOS and power saving options on Toshiba portables.
1265
1266	  For information on utilities to make use of this driver see the
1267	  Toshiba Linux utilities web site at:
1268	  <http://www.buzzard.org.uk/toshiba/>.
1269
1270	  Say Y if you intend to run this kernel on a Toshiba portable.
1271	  Say N otherwise.
1272
1273config I8K
1274	tristate "Dell i8k legacy laptop support"
1275	select HWMON
1276	select SENSORS_DELL_SMM
1277	---help---
1278	  This option enables legacy /proc/i8k userspace interface in hwmon
1279	  dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1280	  temperature and allows controlling fan speeds of Dell laptops via
1281	  System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1282	  it reports also power and hotkey status. For fan speed control is
1283	  needed userspace package i8kutils.
1284
1285	  Say Y if you intend to run this kernel on old Dell laptops or want to
1286	  use userspace package i8kutils.
1287	  Say N otherwise.
1288
1289config X86_REBOOTFIXUPS
1290	bool "Enable X86 board specific fixups for reboot"
1291	depends on X86_32
1292	---help---
1293	  This enables chipset and/or board specific fixups to be done
1294	  in order to get reboot to work correctly. This is only needed on
1295	  some combinations of hardware and BIOS. The symptom, for which
1296	  this config is intended, is when reboot ends with a stalled/hung
1297	  system.
1298
1299	  Currently, the only fixup is for the Geode machines using
1300	  CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1301
1302	  Say Y if you want to enable the fixup. Currently, it's safe to
1303	  enable this option even if you don't need it.
1304	  Say N otherwise.
1305
1306config MICROCODE
1307	bool "CPU microcode loading support"
1308	default y
1309	depends on CPU_SUP_AMD || CPU_SUP_INTEL
1310	select FW_LOADER
1311	---help---
1312	  If you say Y here, you will be able to update the microcode on
1313	  Intel and AMD processors. The Intel support is for the IA32 family,
1314	  e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1315	  AMD support is for families 0x10 and later. You will obviously need
1316	  the actual microcode binary data itself which is not shipped with
1317	  the Linux kernel.
1318
1319	  The preferred method to load microcode from a detached initrd is described
1320	  in Documentation/x86/microcode.rst. For that you need to enable
1321	  CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1322	  initrd for microcode blobs.
1323
1324	  In addition, you can build the microcode into the kernel. For that you
1325	  need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1326	  config option.
1327
1328config MICROCODE_INTEL
1329	bool "Intel microcode loading support"
1330	depends on MICROCODE
1331	default MICROCODE
1332	select FW_LOADER
1333	---help---
1334	  This options enables microcode patch loading support for Intel
1335	  processors.
1336
1337	  For the current Intel microcode data package go to
1338	  <https://downloadcenter.intel.com> and search for
1339	  'Linux Processor Microcode Data File'.
1340
1341config MICROCODE_AMD
1342	bool "AMD microcode loading support"
1343	depends on MICROCODE
1344	select FW_LOADER
1345	---help---
1346	  If you select this option, microcode patch loading support for AMD
1347	  processors will be enabled.
1348
1349config MICROCODE_OLD_INTERFACE
1350	bool "Ancient loading interface (DEPRECATED)"
1351	default n
1352	depends on MICROCODE
1353	---help---
1354	  DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1355	  which was used by userspace tools like iucode_tool and microcode.ctl.
1356	  It is inadequate because it runs too late to be able to properly
1357	  load microcode on a machine and it needs special tools. Instead, you
1358	  should've switched to the early loading method with the initrd or
1359	  builtin microcode by now: Documentation/x86/microcode.rst
1360
1361config X86_MSR
1362	tristate "/dev/cpu/*/msr - Model-specific register support"
1363	---help---
1364	  This device gives privileged processes access to the x86
1365	  Model-Specific Registers (MSRs).  It is a character device with
1366	  major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1367	  MSR accesses are directed to a specific CPU on multi-processor
1368	  systems.
1369
1370config X86_CPUID
1371	tristate "/dev/cpu/*/cpuid - CPU information support"
1372	---help---
1373	  This device gives processes access to the x86 CPUID instruction to
1374	  be executed on a specific processor.  It is a character device
1375	  with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1376	  /dev/cpu/31/cpuid.
1377
1378choice
1379	prompt "High Memory Support"
1380	default HIGHMEM4G
1381	depends on X86_32
1382
1383config NOHIGHMEM
1384	bool "off"
1385	---help---
1386	  Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1387	  However, the address space of 32-bit x86 processors is only 4
1388	  Gigabytes large. That means that, if you have a large amount of
1389	  physical memory, not all of it can be "permanently mapped" by the
1390	  kernel. The physical memory that's not permanently mapped is called
1391	  "high memory".
1392
1393	  If you are compiling a kernel which will never run on a machine with
1394	  more than 1 Gigabyte total physical RAM, answer "off" here (default
1395	  choice and suitable for most users). This will result in a "3GB/1GB"
1396	  split: 3GB are mapped so that each process sees a 3GB virtual memory
1397	  space and the remaining part of the 4GB virtual memory space is used
1398	  by the kernel to permanently map as much physical memory as
1399	  possible.
1400
1401	  If the machine has between 1 and 4 Gigabytes physical RAM, then
1402	  answer "4GB" here.
1403
1404	  If more than 4 Gigabytes is used then answer "64GB" here. This
1405	  selection turns Intel PAE (Physical Address Extension) mode on.
1406	  PAE implements 3-level paging on IA32 processors. PAE is fully
1407	  supported by Linux, PAE mode is implemented on all recent Intel
1408	  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1409	  then the kernel will not boot on CPUs that don't support PAE!
1410
1411	  The actual amount of total physical memory will either be
1412	  auto detected or can be forced by using a kernel command line option
1413	  such as "mem=256M". (Try "man bootparam" or see the documentation of
1414	  your boot loader (lilo or loadlin) about how to pass options to the
1415	  kernel at boot time.)
1416
1417	  If unsure, say "off".
1418
1419config HIGHMEM4G
1420	bool "4GB"
1421	---help---
1422	  Select this if you have a 32-bit processor and between 1 and 4
1423	  gigabytes of physical RAM.
1424
1425config HIGHMEM64G
1426	bool "64GB"
1427	depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1428	select X86_PAE
1429	---help---
1430	  Select this if you have a 32-bit processor and more than 4
1431	  gigabytes of physical RAM.
1432
1433endchoice
1434
1435choice
1436	prompt "Memory split" if EXPERT
1437	default VMSPLIT_3G
1438	depends on X86_32
1439	---help---
1440	  Select the desired split between kernel and user memory.
1441
1442	  If the address range available to the kernel is less than the
1443	  physical memory installed, the remaining memory will be available
1444	  as "high memory". Accessing high memory is a little more costly
1445	  than low memory, as it needs to be mapped into the kernel first.
1446	  Note that increasing the kernel address space limits the range
1447	  available to user programs, making the address space there
1448	  tighter.  Selecting anything other than the default 3G/1G split
1449	  will also likely make your kernel incompatible with binary-only
1450	  kernel modules.
1451
1452	  If you are not absolutely sure what you are doing, leave this
1453	  option alone!
1454
1455	config VMSPLIT_3G
1456		bool "3G/1G user/kernel split"
1457	config VMSPLIT_3G_OPT
1458		depends on !X86_PAE
1459		bool "3G/1G user/kernel split (for full 1G low memory)"
1460	config VMSPLIT_2G
1461		bool "2G/2G user/kernel split"
1462	config VMSPLIT_2G_OPT
1463		depends on !X86_PAE
1464		bool "2G/2G user/kernel split (for full 2G low memory)"
1465	config VMSPLIT_1G
1466		bool "1G/3G user/kernel split"
1467endchoice
1468
1469config PAGE_OFFSET
1470	hex
1471	default 0xB0000000 if VMSPLIT_3G_OPT
1472	default 0x80000000 if VMSPLIT_2G
1473	default 0x78000000 if VMSPLIT_2G_OPT
1474	default 0x40000000 if VMSPLIT_1G
1475	default 0xC0000000
1476	depends on X86_32
1477
1478config HIGHMEM
1479	def_bool y
1480	depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1481
1482config X86_PAE
1483	bool "PAE (Physical Address Extension) Support"
1484	depends on X86_32 && !HIGHMEM4G
1485	select PHYS_ADDR_T_64BIT
1486	select SWIOTLB
1487	---help---
1488	  PAE is required for NX support, and furthermore enables
1489	  larger swapspace support for non-overcommit purposes. It
1490	  has the cost of more pagetable lookup overhead, and also
1491	  consumes more pagetable space per process.
1492
1493config X86_5LEVEL
1494	bool "Enable 5-level page tables support"
1495	select DYNAMIC_MEMORY_LAYOUT
1496	select SPARSEMEM_VMEMMAP
1497	depends on X86_64
1498	---help---
1499	  5-level paging enables access to larger address space:
1500	  upto 128 PiB of virtual address space and 4 PiB of
1501	  physical address space.
1502
1503	  It will be supported by future Intel CPUs.
1504
1505	  A kernel with the option enabled can be booted on machines that
1506	  support 4- or 5-level paging.
1507
1508	  See Documentation/x86/x86_64/5level-paging.rst for more
1509	  information.
1510
1511	  Say N if unsure.
1512
1513config X86_DIRECT_GBPAGES
1514	def_bool y
1515	depends on X86_64
1516	---help---
1517	  Certain kernel features effectively disable kernel
1518	  linear 1 GB mappings (even if the CPU otherwise
1519	  supports them), so don't confuse the user by printing
1520	  that we have them enabled.
1521
1522config X86_CPA_STATISTICS
1523	bool "Enable statistic for Change Page Attribute"
1524	depends on DEBUG_FS
1525	---help---
1526	  Expose statistics about the Change Page Attribute mechanims, which
1527	  helps to determine the effectiveness of preserving large and huge
1528	  page mappings when mapping protections are changed.
1529
1530config AMD_MEM_ENCRYPT
1531	bool "AMD Secure Memory Encryption (SME) support"
1532	depends on X86_64 && CPU_SUP_AMD
1533	select DYNAMIC_PHYSICAL_MASK
1534	select ARCH_USE_MEMREMAP_PROT
1535	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1536	---help---
1537	  Say yes to enable support for the encryption of system memory.
1538	  This requires an AMD processor that supports Secure Memory
1539	  Encryption (SME).
1540
1541config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1542	bool "Activate AMD Secure Memory Encryption (SME) by default"
1543	default y
1544	depends on AMD_MEM_ENCRYPT
1545	---help---
1546	  Say yes to have system memory encrypted by default if running on
1547	  an AMD processor that supports Secure Memory Encryption (SME).
1548
1549	  If set to Y, then the encryption of system memory can be
1550	  deactivated with the mem_encrypt=off command line option.
1551
1552	  If set to N, then the encryption of system memory can be
1553	  activated with the mem_encrypt=on command line option.
1554
1555# Common NUMA Features
1556config NUMA
1557	bool "Numa Memory Allocation and Scheduler Support"
1558	depends on SMP
1559	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1560	default y if X86_BIGSMP
1561	---help---
1562	  Enable NUMA (Non Uniform Memory Access) support.
1563
1564	  The kernel will try to allocate memory used by a CPU on the
1565	  local memory controller of the CPU and add some more
1566	  NUMA awareness to the kernel.
1567
1568	  For 64-bit this is recommended if the system is Intel Core i7
1569	  (or later), AMD Opteron, or EM64T NUMA.
1570
1571	  For 32-bit this is only needed if you boot a 32-bit
1572	  kernel on a 64-bit NUMA platform.
1573
1574	  Otherwise, you should say N.
1575
1576config AMD_NUMA
1577	def_bool y
1578	prompt "Old style AMD Opteron NUMA detection"
1579	depends on X86_64 && NUMA && PCI
1580	---help---
1581	  Enable AMD NUMA node topology detection.  You should say Y here if
1582	  you have a multi processor AMD system. This uses an old method to
1583	  read the NUMA configuration directly from the builtin Northbridge
1584	  of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1585	  which also takes priority if both are compiled in.
1586
1587config X86_64_ACPI_NUMA
1588	def_bool y
1589	prompt "ACPI NUMA detection"
1590	depends on X86_64 && NUMA && ACPI && PCI
1591	select ACPI_NUMA
1592	---help---
1593	  Enable ACPI SRAT based node topology detection.
1594
1595# Some NUMA nodes have memory ranges that span
1596# other nodes.  Even though a pfn is valid and
1597# between a node's start and end pfns, it may not
1598# reside on that node.  See memmap_init_zone()
1599# for details.
1600config NODES_SPAN_OTHER_NODES
1601	def_bool y
1602	depends on X86_64_ACPI_NUMA
1603
1604config NUMA_EMU
1605	bool "NUMA emulation"
1606	depends on NUMA
1607	---help---
1608	  Enable NUMA emulation. A flat machine will be split
1609	  into virtual nodes when booted with "numa=fake=N", where N is the
1610	  number of nodes. This is only useful for debugging.
1611
1612config NODES_SHIFT
1613	int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1614	range 1 10
1615	default "10" if MAXSMP
1616	default "6" if X86_64
1617	default "3"
1618	depends on NEED_MULTIPLE_NODES
1619	---help---
1620	  Specify the maximum number of NUMA Nodes available on the target
1621	  system.  Increases memory reserved to accommodate various tables.
1622
1623config ARCH_HAVE_MEMORY_PRESENT
1624	def_bool y
1625	depends on X86_32 && DISCONTIGMEM
1626
1627config ARCH_FLATMEM_ENABLE
1628	def_bool y
1629	depends on X86_32 && !NUMA
1630
1631config ARCH_DISCONTIGMEM_ENABLE
1632	def_bool n
1633	depends on NUMA && X86_32
1634	depends on BROKEN
1635
1636config ARCH_SPARSEMEM_ENABLE
1637	def_bool y
1638	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1639	select SPARSEMEM_STATIC if X86_32
1640	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1641
1642config ARCH_SPARSEMEM_DEFAULT
1643	def_bool X86_64 || (NUMA && X86_32)
1644
1645config ARCH_SELECT_MEMORY_MODEL
1646	def_bool y
1647	depends on ARCH_SPARSEMEM_ENABLE
1648
1649config ARCH_MEMORY_PROBE
1650	bool "Enable sysfs memory/probe interface"
1651	depends on X86_64 && MEMORY_HOTPLUG
1652	help
1653	  This option enables a sysfs memory/probe interface for testing.
1654	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1655	  If you are unsure how to answer this question, answer N.
1656
1657config ARCH_PROC_KCORE_TEXT
1658	def_bool y
1659	depends on X86_64 && PROC_KCORE
1660
1661config ILLEGAL_POINTER_VALUE
1662       hex
1663       default 0 if X86_32
1664       default 0xdead000000000000 if X86_64
1665
1666config X86_PMEM_LEGACY_DEVICE
1667	bool
1668
1669config X86_PMEM_LEGACY
1670	tristate "Support non-standard NVDIMMs and ADR protected memory"
1671	depends on PHYS_ADDR_T_64BIT
1672	depends on BLK_DEV
1673	select X86_PMEM_LEGACY_DEVICE
1674	select LIBNVDIMM
1675	help
1676	  Treat memory marked using the non-standard e820 type of 12 as used
1677	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1678	  The kernel will offer these regions to the 'pmem' driver so
1679	  they can be used for persistent storage.
1680
1681	  Say Y if unsure.
1682
1683config HIGHPTE
1684	bool "Allocate 3rd-level pagetables from highmem"
1685	depends on HIGHMEM
1686	---help---
1687	  The VM uses one page table entry for each page of physical memory.
1688	  For systems with a lot of RAM, this can be wasteful of precious
1689	  low memory.  Setting this option will put user-space page table
1690	  entries in high memory.
1691
1692config X86_CHECK_BIOS_CORRUPTION
1693	bool "Check for low memory corruption"
1694	---help---
1695	  Periodically check for memory corruption in low memory, which
1696	  is suspected to be caused by BIOS.  Even when enabled in the
1697	  configuration, it is disabled at runtime.  Enable it by
1698	  setting "memory_corruption_check=1" on the kernel command
1699	  line.  By default it scans the low 64k of memory every 60
1700	  seconds; see the memory_corruption_check_size and
1701	  memory_corruption_check_period parameters in
1702	  Documentation/admin-guide/kernel-parameters.rst to adjust this.
1703
1704	  When enabled with the default parameters, this option has
1705	  almost no overhead, as it reserves a relatively small amount
1706	  of memory and scans it infrequently.  It both detects corruption
1707	  and prevents it from affecting the running system.
1708
1709	  It is, however, intended as a diagnostic tool; if repeatable
1710	  BIOS-originated corruption always affects the same memory,
1711	  you can use memmap= to prevent the kernel from using that
1712	  memory.
1713
1714config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1715	bool "Set the default setting of memory_corruption_check"
1716	depends on X86_CHECK_BIOS_CORRUPTION
1717	default y
1718	---help---
1719	  Set whether the default state of memory_corruption_check is
1720	  on or off.
1721
1722config X86_RESERVE_LOW
1723	int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1724	default 64
1725	range 4 640
1726	---help---
1727	  Specify the amount of low memory to reserve for the BIOS.
1728
1729	  The first page contains BIOS data structures that the kernel
1730	  must not use, so that page must always be reserved.
1731
1732	  By default we reserve the first 64K of physical RAM, as a
1733	  number of BIOSes are known to corrupt that memory range
1734	  during events such as suspend/resume or monitor cable
1735	  insertion, so it must not be used by the kernel.
1736
1737	  You can set this to 4 if you are absolutely sure that you
1738	  trust the BIOS to get all its memory reservations and usages
1739	  right.  If you know your BIOS have problems beyond the
1740	  default 64K area, you can set this to 640 to avoid using the
1741	  entire low memory range.
1742
1743	  If you have doubts about the BIOS (e.g. suspend/resume does
1744	  not work or there's kernel crashes after certain hardware
1745	  hotplug events) then you might want to enable
1746	  X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1747	  typical corruption patterns.
1748
1749	  Leave this to the default value of 64 if you are unsure.
1750
1751config MATH_EMULATION
1752	bool
1753	depends on MODIFY_LDT_SYSCALL
1754	prompt "Math emulation" if X86_32
1755	---help---
1756	  Linux can emulate a math coprocessor (used for floating point
1757	  operations) if you don't have one. 486DX and Pentium processors have
1758	  a math coprocessor built in, 486SX and 386 do not, unless you added
1759	  a 487DX or 387, respectively. (The messages during boot time can
1760	  give you some hints here ["man dmesg"].) Everyone needs either a
1761	  coprocessor or this emulation.
1762
1763	  If you don't have a math coprocessor, you need to say Y here; if you
1764	  say Y here even though you have a coprocessor, the coprocessor will
1765	  be used nevertheless. (This behavior can be changed with the kernel
1766	  command line option "no387", which comes handy if your coprocessor
1767	  is broken. Try "man bootparam" or see the documentation of your boot
1768	  loader (lilo or loadlin) about how to pass options to the kernel at
1769	  boot time.) This means that it is a good idea to say Y here if you
1770	  intend to use this kernel on different machines.
1771
1772	  More information about the internals of the Linux math coprocessor
1773	  emulation can be found in <file:arch/x86/math-emu/README>.
1774
1775	  If you are not sure, say Y; apart from resulting in a 66 KB bigger
1776	  kernel, it won't hurt.
1777
1778config MTRR
1779	def_bool y
1780	prompt "MTRR (Memory Type Range Register) support" if EXPERT
1781	---help---
1782	  On Intel P6 family processors (Pentium Pro, Pentium II and later)
1783	  the Memory Type Range Registers (MTRRs) may be used to control
1784	  processor access to memory ranges. This is most useful if you have
1785	  a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1786	  allows bus write transfers to be combined into a larger transfer
1787	  before bursting over the PCI/AGP bus. This can increase performance
1788	  of image write operations 2.5 times or more. Saying Y here creates a
1789	  /proc/mtrr file which may be used to manipulate your processor's
1790	  MTRRs. Typically the X server should use this.
1791
1792	  This code has a reasonably generic interface so that similar
1793	  control registers on other processors can be easily supported
1794	  as well:
1795
1796	  The Cyrix 6x86, 6x86MX and M II processors have Address Range
1797	  Registers (ARRs) which provide a similar functionality to MTRRs. For
1798	  these, the ARRs are used to emulate the MTRRs.
1799	  The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1800	  MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1801	  write-combining. All of these processors are supported by this code
1802	  and it makes sense to say Y here if you have one of them.
1803
1804	  Saying Y here also fixes a problem with buggy SMP BIOSes which only
1805	  set the MTRRs for the boot CPU and not for the secondary CPUs. This
1806	  can lead to all sorts of problems, so it's good to say Y here.
1807
1808	  You can safely say Y even if your machine doesn't have MTRRs, you'll
1809	  just add about 9 KB to your kernel.
1810
1811	  See <file:Documentation/x86/mtrr.rst> for more information.
1812
1813config MTRR_SANITIZER
1814	def_bool y
1815	prompt "MTRR cleanup support"
1816	depends on MTRR
1817	---help---
1818	  Convert MTRR layout from continuous to discrete, so X drivers can
1819	  add writeback entries.
1820
1821	  Can be disabled with disable_mtrr_cleanup on the kernel command line.
1822	  The largest mtrr entry size for a continuous block can be set with
1823	  mtrr_chunk_size.
1824
1825	  If unsure, say Y.
1826
1827config MTRR_SANITIZER_ENABLE_DEFAULT
1828	int "MTRR cleanup enable value (0-1)"
1829	range 0 1
1830	default "0"
1831	depends on MTRR_SANITIZER
1832	---help---
1833	  Enable mtrr cleanup default value
1834
1835config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1836	int "MTRR cleanup spare reg num (0-7)"
1837	range 0 7
1838	default "1"
1839	depends on MTRR_SANITIZER
1840	---help---
1841	  mtrr cleanup spare entries default, it can be changed via
1842	  mtrr_spare_reg_nr=N on the kernel command line.
1843
1844config X86_PAT
1845	def_bool y
1846	prompt "x86 PAT support" if EXPERT
1847	depends on MTRR
1848	---help---
1849	  Use PAT attributes to setup page level cache control.
1850
1851	  PATs are the modern equivalents of MTRRs and are much more
1852	  flexible than MTRRs.
1853
1854	  Say N here if you see bootup problems (boot crash, boot hang,
1855	  spontaneous reboots) or a non-working video driver.
1856
1857	  If unsure, say Y.
1858
1859config ARCH_USES_PG_UNCACHED
1860	def_bool y
1861	depends on X86_PAT
1862
1863config ARCH_RANDOM
1864	def_bool y
1865	prompt "x86 architectural random number generator" if EXPERT
1866	---help---
1867	  Enable the x86 architectural RDRAND instruction
1868	  (Intel Bull Mountain technology) to generate random numbers.
1869	  If supported, this is a high bandwidth, cryptographically
1870	  secure hardware random number generator.
1871
1872config X86_SMAP
1873	def_bool y
1874	prompt "Supervisor Mode Access Prevention" if EXPERT
1875	---help---
1876	  Supervisor Mode Access Prevention (SMAP) is a security
1877	  feature in newer Intel processors.  There is a small
1878	  performance cost if this enabled and turned on; there is
1879	  also a small increase in the kernel size if this is enabled.
1880
1881	  If unsure, say Y.
1882
1883config X86_INTEL_UMIP
1884	def_bool y
1885	depends on CPU_SUP_INTEL
1886	prompt "Intel User Mode Instruction Prevention" if EXPERT
1887	---help---
1888	  The User Mode Instruction Prevention (UMIP) is a security
1889	  feature in newer Intel processors. If enabled, a general
1890	  protection fault is issued if the SGDT, SLDT, SIDT, SMSW
1891	  or STR instructions are executed in user mode. These instructions
1892	  unnecessarily expose information about the hardware state.
1893
1894	  The vast majority of applications do not use these instructions.
1895	  For the very few that do, software emulation is provided in
1896	  specific cases in protected and virtual-8086 modes. Emulated
1897	  results are dummy.
1898
1899config X86_INTEL_MPX
1900	prompt "Intel MPX (Memory Protection Extensions)"
1901	def_bool n
1902	# Note: only available in 64-bit mode due to VMA flags shortage
1903	depends on CPU_SUP_INTEL && X86_64
1904	select ARCH_USES_HIGH_VMA_FLAGS
1905	---help---
1906	  MPX provides hardware features that can be used in
1907	  conjunction with compiler-instrumented code to check
1908	  memory references.  It is designed to detect buffer
1909	  overflow or underflow bugs.
1910
1911	  This option enables running applications which are
1912	  instrumented or otherwise use MPX.  It does not use MPX
1913	  itself inside the kernel or to protect the kernel
1914	  against bad memory references.
1915
1916	  Enabling this option will make the kernel larger:
1917	  ~8k of kernel text and 36 bytes of data on a 64-bit
1918	  defconfig.  It adds a long to the 'mm_struct' which
1919	  will increase the kernel memory overhead of each
1920	  process and adds some branches to paths used during
1921	  exec() and munmap().
1922
1923	  For details, see Documentation/x86/intel_mpx.rst
1924
1925	  If unsure, say N.
1926
1927config X86_INTEL_MEMORY_PROTECTION_KEYS
1928	prompt "Intel Memory Protection Keys"
1929	def_bool y
1930	# Note: only available in 64-bit mode
1931	depends on CPU_SUP_INTEL && X86_64
1932	select ARCH_USES_HIGH_VMA_FLAGS
1933	select ARCH_HAS_PKEYS
1934	---help---
1935	  Memory Protection Keys provides a mechanism for enforcing
1936	  page-based protections, but without requiring modification of the
1937	  page tables when an application changes protection domains.
1938
1939	  For details, see Documentation/core-api/protection-keys.rst
1940
1941	  If unsure, say y.
1942
1943choice
1944	prompt "TSX enable mode"
1945	depends on CPU_SUP_INTEL
1946	default X86_INTEL_TSX_MODE_OFF
1947	help
1948	  Intel's TSX (Transactional Synchronization Extensions) feature
1949	  allows to optimize locking protocols through lock elision which
1950	  can lead to a noticeable performance boost.
1951
1952	  On the other hand it has been shown that TSX can be exploited
1953	  to form side channel attacks (e.g. TAA) and chances are there
1954	  will be more of those attacks discovered in the future.
1955
1956	  Therefore TSX is not enabled by default (aka tsx=off). An admin
1957	  might override this decision by tsx=on the command line parameter.
1958	  Even with TSX enabled, the kernel will attempt to enable the best
1959	  possible TAA mitigation setting depending on the microcode available
1960	  for the particular machine.
1961
1962	  This option allows to set the default tsx mode between tsx=on, =off
1963	  and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1964	  details.
1965
1966	  Say off if not sure, auto if TSX is in use but it should be used on safe
1967	  platforms or on if TSX is in use and the security aspect of tsx is not
1968	  relevant.
1969
1970config X86_INTEL_TSX_MODE_OFF
1971	bool "off"
1972	help
1973	  TSX is disabled if possible - equals to tsx=off command line parameter.
1974
1975config X86_INTEL_TSX_MODE_ON
1976	bool "on"
1977	help
1978	  TSX is always enabled on TSX capable HW - equals the tsx=on command
1979	  line parameter.
1980
1981config X86_INTEL_TSX_MODE_AUTO
1982	bool "auto"
1983	help
1984	  TSX is enabled on TSX capable HW that is believed to be safe against
1985	  side channel attacks- equals the tsx=auto command line parameter.
1986endchoice
1987
1988config EFI
1989	bool "EFI runtime service support"
1990	depends on ACPI
1991	select UCS2_STRING
1992	select EFI_RUNTIME_WRAPPERS
1993	---help---
1994	  This enables the kernel to use EFI runtime services that are
1995	  available (such as the EFI variable services).
1996
1997	  This option is only useful on systems that have EFI firmware.
1998	  In addition, you should use the latest ELILO loader available
1999	  at <http://elilo.sourceforge.net> in order to take advantage
2000	  of EFI runtime services. However, even with this option, the
2001	  resultant kernel should continue to boot on existing non-EFI
2002	  platforms.
2003
2004config EFI_STUB
2005       bool "EFI stub support"
2006       depends on EFI && !X86_USE_3DNOW
2007       select RELOCATABLE
2008       ---help---
2009          This kernel feature allows a bzImage to be loaded directly
2010	  by EFI firmware without the use of a bootloader.
2011
2012	  See Documentation/admin-guide/efi-stub.rst for more information.
2013
2014config EFI_MIXED
2015	bool "EFI mixed-mode support"
2016	depends on EFI_STUB && X86_64
2017	---help---
2018	   Enabling this feature allows a 64-bit kernel to be booted
2019	   on a 32-bit firmware, provided that your CPU supports 64-bit
2020	   mode.
2021
2022	   Note that it is not possible to boot a mixed-mode enabled
2023	   kernel via the EFI boot stub - a bootloader that supports
2024	   the EFI handover protocol must be used.
2025
2026	   If unsure, say N.
2027
2028config SECCOMP
2029	def_bool y
2030	prompt "Enable seccomp to safely compute untrusted bytecode"
2031	---help---
2032	  This kernel feature is useful for number crunching applications
2033	  that may need to compute untrusted bytecode during their
2034	  execution. By using pipes or other transports made available to
2035	  the process as file descriptors supporting the read/write
2036	  syscalls, it's possible to isolate those applications in
2037	  their own address space using seccomp. Once seccomp is
2038	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
2039	  and the task is only allowed to execute a few safe syscalls
2040	  defined by each seccomp mode.
2041
2042	  If unsure, say Y. Only embedded should say N here.
2043
2044source "kernel/Kconfig.hz"
2045
2046config KEXEC
2047	bool "kexec system call"
2048	select KEXEC_CORE
2049	---help---
2050	  kexec is a system call that implements the ability to shutdown your
2051	  current kernel, and to start another kernel.  It is like a reboot
2052	  but it is independent of the system firmware.   And like a reboot
2053	  you can start any kernel with it, not just Linux.
2054
2055	  The name comes from the similarity to the exec system call.
2056
2057	  It is an ongoing process to be certain the hardware in a machine
2058	  is properly shutdown, so do not be surprised if this code does not
2059	  initially work for you.  As of this writing the exact hardware
2060	  interface is strongly in flux, so no good recommendation can be
2061	  made.
2062
2063config KEXEC_FILE
2064	bool "kexec file based system call"
2065	select KEXEC_CORE
2066	select BUILD_BIN2C
2067	depends on X86_64
2068	depends on CRYPTO=y
2069	depends on CRYPTO_SHA256=y
2070	---help---
2071	  This is new version of kexec system call. This system call is
2072	  file based and takes file descriptors as system call argument
2073	  for kernel and initramfs as opposed to list of segments as
2074	  accepted by previous system call.
2075
2076config ARCH_HAS_KEXEC_PURGATORY
2077	def_bool KEXEC_FILE
2078
2079config KEXEC_SIG
2080	bool "Verify kernel signature during kexec_file_load() syscall"
2081	depends on KEXEC_FILE
2082	---help---
2083
2084	  This option makes the kexec_file_load() syscall check for a valid
2085	  signature of the kernel image.  The image can still be loaded without
2086	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2087	  there's a signature that we can check, then it must be valid.
2088
2089	  In addition to this option, you need to enable signature
2090	  verification for the corresponding kernel image type being
2091	  loaded in order for this to work.
2092
2093config KEXEC_SIG_FORCE
2094	bool "Require a valid signature in kexec_file_load() syscall"
2095	depends on KEXEC_SIG
2096	---help---
2097	  This option makes kernel signature verification mandatory for
2098	  the kexec_file_load() syscall.
2099
2100config KEXEC_BZIMAGE_VERIFY_SIG
2101	bool "Enable bzImage signature verification support"
2102	depends on KEXEC_SIG
2103	depends on SIGNED_PE_FILE_VERIFICATION
2104	select SYSTEM_TRUSTED_KEYRING
2105	---help---
2106	  Enable bzImage signature verification support.
2107
2108config CRASH_DUMP
2109	bool "kernel crash dumps"
2110	depends on X86_64 || (X86_32 && HIGHMEM)
2111	---help---
2112	  Generate crash dump after being started by kexec.
2113	  This should be normally only set in special crash dump kernels
2114	  which are loaded in the main kernel with kexec-tools into
2115	  a specially reserved region and then later executed after
2116	  a crash by kdump/kexec. The crash dump kernel must be compiled
2117	  to a memory address not used by the main kernel or BIOS using
2118	  PHYSICAL_START, or it must be built as a relocatable image
2119	  (CONFIG_RELOCATABLE=y).
2120	  For more details see Documentation/admin-guide/kdump/kdump.rst
2121
2122config KEXEC_JUMP
2123	bool "kexec jump"
2124	depends on KEXEC && HIBERNATION
2125	---help---
2126	  Jump between original kernel and kexeced kernel and invoke
2127	  code in physical address mode via KEXEC
2128
2129config PHYSICAL_START
2130	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2131	default "0x1000000"
2132	---help---
2133	  This gives the physical address where the kernel is loaded.
2134
2135	  If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2136	  bzImage will decompress itself to above physical address and
2137	  run from there. Otherwise, bzImage will run from the address where
2138	  it has been loaded by the boot loader and will ignore above physical
2139	  address.
2140
2141	  In normal kdump cases one does not have to set/change this option
2142	  as now bzImage can be compiled as a completely relocatable image
2143	  (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2144	  address. This option is mainly useful for the folks who don't want
2145	  to use a bzImage for capturing the crash dump and want to use a
2146	  vmlinux instead. vmlinux is not relocatable hence a kernel needs
2147	  to be specifically compiled to run from a specific memory area
2148	  (normally a reserved region) and this option comes handy.
2149
2150	  So if you are using bzImage for capturing the crash dump,
2151	  leave the value here unchanged to 0x1000000 and set
2152	  CONFIG_RELOCATABLE=y.  Otherwise if you plan to use vmlinux
2153	  for capturing the crash dump change this value to start of
2154	  the reserved region.  In other words, it can be set based on
2155	  the "X" value as specified in the "crashkernel=YM@XM"
2156	  command line boot parameter passed to the panic-ed
2157	  kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2158	  for more details about crash dumps.
2159
2160	  Usage of bzImage for capturing the crash dump is recommended as
2161	  one does not have to build two kernels. Same kernel can be used
2162	  as production kernel and capture kernel. Above option should have
2163	  gone away after relocatable bzImage support is introduced. But it
2164	  is present because there are users out there who continue to use
2165	  vmlinux for dump capture. This option should go away down the
2166	  line.
2167
2168	  Don't change this unless you know what you are doing.
2169
2170config RELOCATABLE
2171	bool "Build a relocatable kernel"
2172	default y
2173	---help---
2174	  This builds a kernel image that retains relocation information
2175	  so it can be loaded someplace besides the default 1MB.
2176	  The relocations tend to make the kernel binary about 10% larger,
2177	  but are discarded at runtime.
2178
2179	  One use is for the kexec on panic case where the recovery kernel
2180	  must live at a different physical address than the primary
2181	  kernel.
2182
2183	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2184	  it has been loaded at and the compile time physical address
2185	  (CONFIG_PHYSICAL_START) is used as the minimum location.
2186
2187config RANDOMIZE_BASE
2188	bool "Randomize the address of the kernel image (KASLR)"
2189	depends on RELOCATABLE
2190	default y
2191	---help---
2192	  In support of Kernel Address Space Layout Randomization (KASLR),
2193	  this randomizes the physical address at which the kernel image
2194	  is decompressed and the virtual address where the kernel
2195	  image is mapped, as a security feature that deters exploit
2196	  attempts relying on knowledge of the location of kernel
2197	  code internals.
2198
2199	  On 64-bit, the kernel physical and virtual addresses are
2200	  randomized separately. The physical address will be anywhere
2201	  between 16MB and the top of physical memory (up to 64TB). The
2202	  virtual address will be randomized from 16MB up to 1GB (9 bits
2203	  of entropy). Note that this also reduces the memory space
2204	  available to kernel modules from 1.5GB to 1GB.
2205
2206	  On 32-bit, the kernel physical and virtual addresses are
2207	  randomized together. They will be randomized from 16MB up to
2208	  512MB (8 bits of entropy).
2209
2210	  Entropy is generated using the RDRAND instruction if it is
2211	  supported. If RDTSC is supported, its value is mixed into
2212	  the entropy pool as well. If neither RDRAND nor RDTSC are
2213	  supported, then entropy is read from the i8254 timer. The
2214	  usable entropy is limited by the kernel being built using
2215	  2GB addressing, and that PHYSICAL_ALIGN must be at a
2216	  minimum of 2MB. As a result, only 10 bits of entropy are
2217	  theoretically possible, but the implementations are further
2218	  limited due to memory layouts.
2219
2220	  If unsure, say Y.
2221
2222# Relocation on x86 needs some additional build support
2223config X86_NEED_RELOCS
2224	def_bool y
2225	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2226
2227config PHYSICAL_ALIGN
2228	hex "Alignment value to which kernel should be aligned"
2229	default "0x200000"
2230	range 0x2000 0x1000000 if X86_32
2231	range 0x200000 0x1000000 if X86_64
2232	---help---
2233	  This value puts the alignment restrictions on physical address
2234	  where kernel is loaded and run from. Kernel is compiled for an
2235	  address which meets above alignment restriction.
2236
2237	  If bootloader loads the kernel at a non-aligned address and
2238	  CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2239	  address aligned to above value and run from there.
2240
2241	  If bootloader loads the kernel at a non-aligned address and
2242	  CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2243	  load address and decompress itself to the address it has been
2244	  compiled for and run from there. The address for which kernel is
2245	  compiled already meets above alignment restrictions. Hence the
2246	  end result is that kernel runs from a physical address meeting
2247	  above alignment restrictions.
2248
2249	  On 32-bit this value must be a multiple of 0x2000. On 64-bit
2250	  this value must be a multiple of 0x200000.
2251
2252	  Don't change this unless you know what you are doing.
2253
2254config DYNAMIC_MEMORY_LAYOUT
2255	bool
2256	---help---
2257	  This option makes base addresses of vmalloc and vmemmap as well as
2258	  __PAGE_OFFSET movable during boot.
2259
2260config RANDOMIZE_MEMORY
2261	bool "Randomize the kernel memory sections"
2262	depends on X86_64
2263	depends on RANDOMIZE_BASE
2264	select DYNAMIC_MEMORY_LAYOUT
2265	default RANDOMIZE_BASE
2266	---help---
2267	   Randomizes the base virtual address of kernel memory sections
2268	   (physical memory mapping, vmalloc & vmemmap). This security feature
2269	   makes exploits relying on predictable memory locations less reliable.
2270
2271	   The order of allocations remains unchanged. Entropy is generated in
2272	   the same way as RANDOMIZE_BASE. Current implementation in the optimal
2273	   configuration have in average 30,000 different possible virtual
2274	   addresses for each memory section.
2275
2276	   If unsure, say Y.
2277
2278config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2279	hex "Physical memory mapping padding" if EXPERT
2280	depends on RANDOMIZE_MEMORY
2281	default "0xa" if MEMORY_HOTPLUG
2282	default "0x0"
2283	range 0x1 0x40 if MEMORY_HOTPLUG
2284	range 0x0 0x40
2285	---help---
2286	   Define the padding in terabytes added to the existing physical
2287	   memory size during kernel memory randomization. It is useful
2288	   for memory hotplug support but reduces the entropy available for
2289	   address randomization.
2290
2291	   If unsure, leave at the default value.
2292
2293config HOTPLUG_CPU
2294	def_bool y
2295	depends on SMP
2296
2297config BOOTPARAM_HOTPLUG_CPU0
2298	bool "Set default setting of cpu0_hotpluggable"
2299	depends on HOTPLUG_CPU
2300	---help---
2301	  Set whether default state of cpu0_hotpluggable is on or off.
2302
2303	  Say Y here to enable CPU0 hotplug by default. If this switch
2304	  is turned on, there is no need to give cpu0_hotplug kernel
2305	  parameter and the CPU0 hotplug feature is enabled by default.
2306
2307	  Please note: there are two known CPU0 dependencies if you want
2308	  to enable the CPU0 hotplug feature either by this switch or by
2309	  cpu0_hotplug kernel parameter.
2310
2311	  First, resume from hibernate or suspend always starts from CPU0.
2312	  So hibernate and suspend are prevented if CPU0 is offline.
2313
2314	  Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2315	  offline if any interrupt can not migrate out of CPU0. There may
2316	  be other CPU0 dependencies.
2317
2318	  Please make sure the dependencies are under your control before
2319	  you enable this feature.
2320
2321	  Say N if you don't want to enable CPU0 hotplug feature by default.
2322	  You still can enable the CPU0 hotplug feature at boot by kernel
2323	  parameter cpu0_hotplug.
2324
2325config DEBUG_HOTPLUG_CPU0
2326	def_bool n
2327	prompt "Debug CPU0 hotplug"
2328	depends on HOTPLUG_CPU
2329	---help---
2330	  Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2331	  soon as possible and boots up userspace with CPU0 offlined. User
2332	  can online CPU0 back after boot time.
2333
2334	  To debug CPU0 hotplug, you need to enable CPU0 offline/online
2335	  feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2336	  compilation or giving cpu0_hotplug kernel parameter at boot.
2337
2338	  If unsure, say N.
2339
2340config COMPAT_VDSO
2341	def_bool n
2342	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2343	depends on COMPAT_32
2344	---help---
2345	  Certain buggy versions of glibc will crash if they are
2346	  presented with a 32-bit vDSO that is not mapped at the address
2347	  indicated in its segment table.
2348
2349	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2350	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2351	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
2352	  the only released version with the bug, but OpenSUSE 9
2353	  contains a buggy "glibc 2.3.2".
2354
2355	  The symptom of the bug is that everything crashes on startup, saying:
2356	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2357
2358	  Saying Y here changes the default value of the vdso32 boot
2359	  option from 1 to 0, which turns off the 32-bit vDSO entirely.
2360	  This works around the glibc bug but hurts performance.
2361
2362	  If unsure, say N: if you are compiling your own kernel, you
2363	  are unlikely to be using a buggy version of glibc.
2364
2365choice
2366	prompt "vsyscall table for legacy applications"
2367	depends on X86_64
2368	default LEGACY_VSYSCALL_XONLY
2369	help
2370	  Legacy user code that does not know how to find the vDSO expects
2371	  to be able to issue three syscalls by calling fixed addresses in
2372	  kernel space. Since this location is not randomized with ASLR,
2373	  it can be used to assist security vulnerability exploitation.
2374
2375	  This setting can be changed at boot time via the kernel command
2376	  line parameter vsyscall=[emulate|xonly|none].
2377
2378	  On a system with recent enough glibc (2.14 or newer) and no
2379	  static binaries, you can say None without a performance penalty
2380	  to improve security.
2381
2382	  If unsure, select "Emulate execution only".
2383
2384	config LEGACY_VSYSCALL_EMULATE
2385		bool "Full emulation"
2386		help
2387		  The kernel traps and emulates calls into the fixed vsyscall
2388		  address mapping. This makes the mapping non-executable, but
2389		  it still contains readable known contents, which could be
2390		  used in certain rare security vulnerability exploits. This
2391		  configuration is recommended when using legacy userspace
2392		  that still uses vsyscalls along with legacy binary
2393		  instrumentation tools that require code to be readable.
2394
2395		  An example of this type of legacy userspace is running
2396		  Pin on an old binary that still uses vsyscalls.
2397
2398	config LEGACY_VSYSCALL_XONLY
2399		bool "Emulate execution only"
2400		help
2401		  The kernel traps and emulates calls into the fixed vsyscall
2402		  address mapping and does not allow reads.  This
2403		  configuration is recommended when userspace might use the
2404		  legacy vsyscall area but support for legacy binary
2405		  instrumentation of legacy code is not needed.  It mitigates
2406		  certain uses of the vsyscall area as an ASLR-bypassing
2407		  buffer.
2408
2409	config LEGACY_VSYSCALL_NONE
2410		bool "None"
2411		help
2412		  There will be no vsyscall mapping at all. This will
2413		  eliminate any risk of ASLR bypass due to the vsyscall
2414		  fixed address mapping. Attempts to use the vsyscalls
2415		  will be reported to dmesg, so that either old or
2416		  malicious userspace programs can be identified.
2417
2418endchoice
2419
2420config CMDLINE_BOOL
2421	bool "Built-in kernel command line"
2422	---help---
2423	  Allow for specifying boot arguments to the kernel at
2424	  build time.  On some systems (e.g. embedded ones), it is
2425	  necessary or convenient to provide some or all of the
2426	  kernel boot arguments with the kernel itself (that is,
2427	  to not rely on the boot loader to provide them.)
2428
2429	  To compile command line arguments into the kernel,
2430	  set this option to 'Y', then fill in the
2431	  boot arguments in CONFIG_CMDLINE.
2432
2433	  Systems with fully functional boot loaders (i.e. non-embedded)
2434	  should leave this option set to 'N'.
2435
2436config CMDLINE
2437	string "Built-in kernel command string"
2438	depends on CMDLINE_BOOL
2439	default ""
2440	---help---
2441	  Enter arguments here that should be compiled into the kernel
2442	  image and used at boot time.  If the boot loader provides a
2443	  command line at boot time, it is appended to this string to
2444	  form the full kernel command line, when the system boots.
2445
2446	  However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2447	  change this behavior.
2448
2449	  In most cases, the command line (whether built-in or provided
2450	  by the boot loader) should specify the device for the root
2451	  file system.
2452
2453config CMDLINE_OVERRIDE
2454	bool "Built-in command line overrides boot loader arguments"
2455	depends on CMDLINE_BOOL
2456	---help---
2457	  Set this option to 'Y' to have the kernel ignore the boot loader
2458	  command line, and use ONLY the built-in command line.
2459
2460	  This is used to work around broken boot loaders.  This should
2461	  be set to 'N' under normal conditions.
2462
2463config MODIFY_LDT_SYSCALL
2464	bool "Enable the LDT (local descriptor table)" if EXPERT
2465	default y
2466	---help---
2467	  Linux can allow user programs to install a per-process x86
2468	  Local Descriptor Table (LDT) using the modify_ldt(2) system
2469	  call.  This is required to run 16-bit or segmented code such as
2470	  DOSEMU or some Wine programs.  It is also used by some very old
2471	  threading libraries.
2472
2473	  Enabling this feature adds a small amount of overhead to
2474	  context switches and increases the low-level kernel attack
2475	  surface.  Disabling it removes the modify_ldt(2) system call.
2476
2477	  Saying 'N' here may make sense for embedded or server kernels.
2478
2479source "kernel/livepatch/Kconfig"
2480
2481endmenu
2482
2483config ARCH_HAS_ADD_PAGES
2484	def_bool y
2485	depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2486
2487config ARCH_ENABLE_MEMORY_HOTPLUG
2488	def_bool y
2489	depends on X86_64 || (X86_32 && HIGHMEM)
2490
2491config ARCH_ENABLE_MEMORY_HOTREMOVE
2492	def_bool y
2493	depends on MEMORY_HOTPLUG
2494
2495config USE_PERCPU_NUMA_NODE_ID
2496	def_bool y
2497	depends on NUMA
2498
2499config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2500	def_bool y
2501	depends on X86_64 || X86_PAE
2502
2503config ARCH_ENABLE_HUGEPAGE_MIGRATION
2504	def_bool y
2505	depends on X86_64 && HUGETLB_PAGE && MIGRATION
2506
2507config ARCH_ENABLE_THP_MIGRATION
2508	def_bool y
2509	depends on X86_64 && TRANSPARENT_HUGEPAGE
2510
2511menu "Power management and ACPI options"
2512
2513config ARCH_HIBERNATION_HEADER
2514	def_bool y
2515	depends on HIBERNATION
2516
2517source "kernel/power/Kconfig"
2518
2519source "drivers/acpi/Kconfig"
2520
2521source "drivers/sfi/Kconfig"
2522
2523config X86_APM_BOOT
2524	def_bool y
2525	depends on APM
2526
2527menuconfig APM
2528	tristate "APM (Advanced Power Management) BIOS support"
2529	depends on X86_32 && PM_SLEEP
2530	---help---
2531	  APM is a BIOS specification for saving power using several different
2532	  techniques. This is mostly useful for battery powered laptops with
2533	  APM compliant BIOSes. If you say Y here, the system time will be
2534	  reset after a RESUME operation, the /proc/apm device will provide
2535	  battery status information, and user-space programs will receive
2536	  notification of APM "events" (e.g. battery status change).
2537
2538	  If you select "Y" here, you can disable actual use of the APM
2539	  BIOS by passing the "apm=off" option to the kernel at boot time.
2540
2541	  Note that the APM support is almost completely disabled for
2542	  machines with more than one CPU.
2543
2544	  In order to use APM, you will need supporting software. For location
2545	  and more information, read <file:Documentation/power/apm-acpi.rst>
2546	  and the Battery Powered Linux mini-HOWTO, available from
2547	  <http://www.tldp.org/docs.html#howto>.
2548
2549	  This driver does not spin down disk drives (see the hdparm(8)
2550	  manpage ("man 8 hdparm") for that), and it doesn't turn off
2551	  VESA-compliant "green" monitors.
2552
2553	  This driver does not support the TI 4000M TravelMate and the ACER
2554	  486/DX4/75 because they don't have compliant BIOSes. Many "green"
2555	  desktop machines also don't have compliant BIOSes, and this driver
2556	  may cause those machines to panic during the boot phase.
2557
2558	  Generally, if you don't have a battery in your machine, there isn't
2559	  much point in using this driver and you should say N. If you get
2560	  random kernel OOPSes or reboots that don't seem to be related to
2561	  anything, try disabling/enabling this option (or disabling/enabling
2562	  APM in your BIOS).
2563
2564	  Some other things you should try when experiencing seemingly random,
2565	  "weird" problems:
2566
2567	  1) make sure that you have enough swap space and that it is
2568	  enabled.
2569	  2) pass the "no-hlt" option to the kernel
2570	  3) switch on floating point emulation in the kernel and pass
2571	  the "no387" option to the kernel
2572	  4) pass the "floppy=nodma" option to the kernel
2573	  5) pass the "mem=4M" option to the kernel (thereby disabling
2574	  all but the first 4 MB of RAM)
2575	  6) make sure that the CPU is not over clocked.
2576	  7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2577	  8) disable the cache from your BIOS settings
2578	  9) install a fan for the video card or exchange video RAM
2579	  10) install a better fan for the CPU
2580	  11) exchange RAM chips
2581	  12) exchange the motherboard.
2582
2583	  To compile this driver as a module, choose M here: the
2584	  module will be called apm.
2585
2586if APM
2587
2588config APM_IGNORE_USER_SUSPEND
2589	bool "Ignore USER SUSPEND"
2590	---help---
2591	  This option will ignore USER SUSPEND requests. On machines with a
2592	  compliant APM BIOS, you want to say N. However, on the NEC Versa M
2593	  series notebooks, it is necessary to say Y because of a BIOS bug.
2594
2595config APM_DO_ENABLE
2596	bool "Enable PM at boot time"
2597	---help---
2598	  Enable APM features at boot time. From page 36 of the APM BIOS
2599	  specification: "When disabled, the APM BIOS does not automatically
2600	  power manage devices, enter the Standby State, enter the Suspend
2601	  State, or take power saving steps in response to CPU Idle calls."
2602	  This driver will make CPU Idle calls when Linux is idle (unless this
2603	  feature is turned off -- see "Do CPU IDLE calls", below). This
2604	  should always save battery power, but more complicated APM features
2605	  will be dependent on your BIOS implementation. You may need to turn
2606	  this option off if your computer hangs at boot time when using APM
2607	  support, or if it beeps continuously instead of suspending. Turn
2608	  this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2609	  T400CDT. This is off by default since most machines do fine without
2610	  this feature.
2611
2612config APM_CPU_IDLE
2613	depends on CPU_IDLE
2614	bool "Make CPU Idle calls when idle"
2615	---help---
2616	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2617	  On some machines, this can activate improved power savings, such as
2618	  a slowed CPU clock rate, when the machine is idle. These idle calls
2619	  are made after the idle loop has run for some length of time (e.g.,
2620	  333 mS). On some machines, this will cause a hang at boot time or
2621	  whenever the CPU becomes idle. (On machines with more than one CPU,
2622	  this option does nothing.)
2623
2624config APM_DISPLAY_BLANK
2625	bool "Enable console blanking using APM"
2626	---help---
2627	  Enable console blanking using the APM. Some laptops can use this to
2628	  turn off the LCD backlight when the screen blanker of the Linux
2629	  virtual console blanks the screen. Note that this is only used by
2630	  the virtual console screen blanker, and won't turn off the backlight
2631	  when using the X Window system. This also doesn't have anything to
2632	  do with your VESA-compliant power-saving monitor. Further, this
2633	  option doesn't work for all laptops -- it might not turn off your
2634	  backlight at all, or it might print a lot of errors to the console,
2635	  especially if you are using gpm.
2636
2637config APM_ALLOW_INTS
2638	bool "Allow interrupts during APM BIOS calls"
2639	---help---
2640	  Normally we disable external interrupts while we are making calls to
2641	  the APM BIOS as a measure to lessen the effects of a badly behaving
2642	  BIOS implementation.  The BIOS should reenable interrupts if it
2643	  needs to.  Unfortunately, some BIOSes do not -- especially those in
2644	  many of the newer IBM Thinkpads.  If you experience hangs when you
2645	  suspend, try setting this to Y.  Otherwise, say N.
2646
2647endif # APM
2648
2649source "drivers/cpufreq/Kconfig"
2650
2651source "drivers/cpuidle/Kconfig"
2652
2653source "drivers/idle/Kconfig"
2654
2655endmenu
2656
2657
2658menu "Bus options (PCI etc.)"
2659
2660choice
2661	prompt "PCI access mode"
2662	depends on X86_32 && PCI
2663	default PCI_GOANY
2664	---help---
2665	  On PCI systems, the BIOS can be used to detect the PCI devices and
2666	  determine their configuration. However, some old PCI motherboards
2667	  have BIOS bugs and may crash if this is done. Also, some embedded
2668	  PCI-based systems don't have any BIOS at all. Linux can also try to
2669	  detect the PCI hardware directly without using the BIOS.
2670
2671	  With this option, you can specify how Linux should detect the
2672	  PCI devices. If you choose "BIOS", the BIOS will be used,
2673	  if you choose "Direct", the BIOS won't be used, and if you
2674	  choose "MMConfig", then PCI Express MMCONFIG will be used.
2675	  If you choose "Any", the kernel will try MMCONFIG, then the
2676	  direct access method and falls back to the BIOS if that doesn't
2677	  work. If unsure, go with the default, which is "Any".
2678
2679config PCI_GOBIOS
2680	bool "BIOS"
2681
2682config PCI_GOMMCONFIG
2683	bool "MMConfig"
2684
2685config PCI_GODIRECT
2686	bool "Direct"
2687
2688config PCI_GOOLPC
2689	bool "OLPC XO-1"
2690	depends on OLPC
2691
2692config PCI_GOANY
2693	bool "Any"
2694
2695endchoice
2696
2697config PCI_BIOS
2698	def_bool y
2699	depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2700
2701# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2702config PCI_DIRECT
2703	def_bool y
2704	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2705
2706config PCI_MMCONFIG
2707	bool "Support mmconfig PCI config space access" if X86_64
2708	default y
2709	depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2710	depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2711
2712config PCI_OLPC
2713	def_bool y
2714	depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2715
2716config PCI_XEN
2717	def_bool y
2718	depends on PCI && XEN
2719	select SWIOTLB_XEN
2720
2721config MMCONF_FAM10H
2722	def_bool y
2723	depends on X86_64 && PCI_MMCONFIG && ACPI
2724
2725config PCI_CNB20LE_QUIRK
2726	bool "Read CNB20LE Host Bridge Windows" if EXPERT
2727	depends on PCI
2728	help
2729	  Read the PCI windows out of the CNB20LE host bridge. This allows
2730	  PCI hotplug to work on systems with the CNB20LE chipset which do
2731	  not have ACPI.
2732
2733	  There's no public spec for this chipset, and this functionality
2734	  is known to be incomplete.
2735
2736	  You should say N unless you know you need this.
2737
2738config ISA_BUS
2739	bool "ISA bus support on modern systems" if EXPERT
2740	help
2741	  Expose ISA bus device drivers and options available for selection and
2742	  configuration. Enable this option if your target machine has an ISA
2743	  bus. ISA is an older system, displaced by PCI and newer bus
2744	  architectures -- if your target machine is modern, it probably does
2745	  not have an ISA bus.
2746
2747	  If unsure, say N.
2748
2749# x86_64 have no ISA slots, but can have ISA-style DMA.
2750config ISA_DMA_API
2751	bool "ISA-style DMA support" if (X86_64 && EXPERT)
2752	default y
2753	help
2754	  Enables ISA-style DMA support for devices requiring such controllers.
2755	  If unsure, say Y.
2756
2757if X86_32
2758
2759config ISA
2760	bool "ISA support"
2761	---help---
2762	  Find out whether you have ISA slots on your motherboard.  ISA is the
2763	  name of a bus system, i.e. the way the CPU talks to the other stuff
2764	  inside your box.  Other bus systems are PCI, EISA, MicroChannel
2765	  (MCA) or VESA.  ISA is an older system, now being displaced by PCI;
2766	  newer boards don't support it.  If you have ISA, say Y, otherwise N.
2767
2768config SCx200
2769	tristate "NatSemi SCx200 support"
2770	---help---
2771	  This provides basic support for National Semiconductor's
2772	  (now AMD's) Geode processors.  The driver probes for the
2773	  PCI-IDs of several on-chip devices, so its a good dependency
2774	  for other scx200_* drivers.
2775
2776	  If compiled as a module, the driver is named scx200.
2777
2778config SCx200HR_TIMER
2779	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2780	depends on SCx200
2781	default y
2782	---help---
2783	  This driver provides a clocksource built upon the on-chip
2784	  27MHz high-resolution timer.  Its also a workaround for
2785	  NSC Geode SC-1100's buggy TSC, which loses time when the
2786	  processor goes idle (as is done by the scheduler).  The
2787	  other workaround is idle=poll boot option.
2788
2789config OLPC
2790	bool "One Laptop Per Child support"
2791	depends on !X86_PAE
2792	select GPIOLIB
2793	select OF
2794	select OF_PROMTREE
2795	select IRQ_DOMAIN
2796	select OLPC_EC
2797	---help---
2798	  Add support for detecting the unique features of the OLPC
2799	  XO hardware.
2800
2801config OLPC_XO1_PM
2802	bool "OLPC XO-1 Power Management"
2803	depends on OLPC && MFD_CS5535=y && PM_SLEEP
2804	---help---
2805	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
2806
2807config OLPC_XO1_RTC
2808	bool "OLPC XO-1 Real Time Clock"
2809	depends on OLPC_XO1_PM && RTC_DRV_CMOS
2810	---help---
2811	  Add support for the XO-1 real time clock, which can be used as a
2812	  programmable wakeup source.
2813
2814config OLPC_XO1_SCI
2815	bool "OLPC XO-1 SCI extras"
2816	depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2817	depends on INPUT=y
2818	select POWER_SUPPLY
2819	---help---
2820	  Add support for SCI-based features of the OLPC XO-1 laptop:
2821	   - EC-driven system wakeups
2822	   - Power button
2823	   - Ebook switch
2824	   - Lid switch
2825	   - AC adapter status updates
2826	   - Battery status updates
2827
2828config OLPC_XO15_SCI
2829	bool "OLPC XO-1.5 SCI extras"
2830	depends on OLPC && ACPI
2831	select POWER_SUPPLY
2832	---help---
2833	  Add support for SCI-based features of the OLPC XO-1.5 laptop:
2834	   - EC-driven system wakeups
2835	   - AC adapter status updates
2836	   - Battery status updates
2837
2838config ALIX
2839	bool "PCEngines ALIX System Support (LED setup)"
2840	select GPIOLIB
2841	---help---
2842	  This option enables system support for the PCEngines ALIX.
2843	  At present this just sets up LEDs for GPIO control on
2844	  ALIX2/3/6 boards.  However, other system specific setup should
2845	  get added here.
2846
2847	  Note: You must still enable the drivers for GPIO and LED support
2848	  (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2849
2850	  Note: You have to set alix.force=1 for boards with Award BIOS.
2851
2852config NET5501
2853	bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2854	select GPIOLIB
2855	---help---
2856	  This option enables system support for the Soekris Engineering net5501.
2857
2858config GEOS
2859	bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2860	select GPIOLIB
2861	depends on DMI
2862	---help---
2863	  This option enables system support for the Traverse Technologies GEOS.
2864
2865config TS5500
2866	bool "Technologic Systems TS-5500 platform support"
2867	depends on MELAN
2868	select CHECK_SIGNATURE
2869	select NEW_LEDS
2870	select LEDS_CLASS
2871	---help---
2872	  This option enables system support for the Technologic Systems TS-5500.
2873
2874endif # X86_32
2875
2876config AMD_NB
2877	def_bool y
2878	depends on CPU_SUP_AMD && PCI
2879
2880config X86_SYSFB
2881	bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2882	help
2883	  Firmwares often provide initial graphics framebuffers so the BIOS,
2884	  bootloader or kernel can show basic video-output during boot for
2885	  user-guidance and debugging. Historically, x86 used the VESA BIOS
2886	  Extensions and EFI-framebuffers for this, which are mostly limited
2887	  to x86.
2888	  This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2889	  framebuffers so the new generic system-framebuffer drivers can be
2890	  used on x86. If the framebuffer is not compatible with the generic
2891	  modes, it is advertised as fallback platform framebuffer so legacy
2892	  drivers like efifb, vesafb and uvesafb can pick it up.
2893	  If this option is not selected, all system framebuffers are always
2894	  marked as fallback platform framebuffers as usual.
2895
2896	  Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2897	  not be able to pick up generic system framebuffers if this option
2898	  is selected. You are highly encouraged to enable simplefb as
2899	  replacement if you select this option. simplefb can correctly deal
2900	  with generic system framebuffers. But you should still keep vesafb
2901	  and others enabled as fallback if a system framebuffer is
2902	  incompatible with simplefb.
2903
2904	  If unsure, say Y.
2905
2906endmenu
2907
2908
2909menu "Binary Emulations"
2910
2911config IA32_EMULATION
2912	bool "IA32 Emulation"
2913	depends on X86_64
2914	select ARCH_WANT_OLD_COMPAT_IPC
2915	select BINFMT_ELF
2916	select COMPAT_BINFMT_ELF
2917	select COMPAT_OLD_SIGACTION
2918	---help---
2919	  Include code to run legacy 32-bit programs under a
2920	  64-bit kernel. You should likely turn this on, unless you're
2921	  100% sure that you don't have any 32-bit programs left.
2922
2923config IA32_AOUT
2924	tristate "IA32 a.out support"
2925	depends on IA32_EMULATION
2926	depends on BROKEN
2927	---help---
2928	  Support old a.out binaries in the 32bit emulation.
2929
2930config X86_X32
2931	bool "x32 ABI for 64-bit mode"
2932	depends on X86_64
2933	---help---
2934	  Include code to run binaries for the x32 native 32-bit ABI
2935	  for 64-bit processors.  An x32 process gets access to the
2936	  full 64-bit register file and wide data path while leaving
2937	  pointers at 32 bits for smaller memory footprint.
2938
2939	  You will need a recent binutils (2.22 or later) with
2940	  elf32_x86_64 support enabled to compile a kernel with this
2941	  option set.
2942
2943config COMPAT_32
2944	def_bool y
2945	depends on IA32_EMULATION || X86_32
2946	select HAVE_UID16
2947	select OLD_SIGSUSPEND3
2948
2949config COMPAT
2950	def_bool y
2951	depends on IA32_EMULATION || X86_X32
2952
2953if COMPAT
2954config COMPAT_FOR_U64_ALIGNMENT
2955	def_bool y
2956
2957config SYSVIPC_COMPAT
2958	def_bool y
2959	depends on SYSVIPC
2960endif
2961
2962endmenu
2963
2964
2965config HAVE_ATOMIC_IOMAP
2966	def_bool y
2967	depends on X86_32
2968
2969config X86_DEV_DMA_OPS
2970	bool
2971
2972source "drivers/firmware/Kconfig"
2973
2974source "arch/x86/kvm/Kconfig"
2975