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b2441318 1# SPDX-License-Identifier: GPL-2.0
daa93fab
SR
2# Select 32 or 64 bit
3config 64BIT
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MY
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
a7f7f624 6 help
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SR
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
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JB
11 def_bool y
12 depends on !64BIT
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IM
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
15 select CLKSRC_I8253
16 select CLONE_BACKWARDS
157e118b 17 select GENERIC_VDSO_32
117ed454 18 select HAVE_DEBUG_STACKOVERFLOW
157e118b 19 select KMAP_LOCAL
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IM
20 select MODULES_USE_ELF_REL
21 select OLD_SIGACTION
2ca408d9 22 select ARCH_SPLIT_ARG64
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SR
23
24config X86_64
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JB
25 def_bool y
26 depends on 64BIT
d94e0685 27 # Options that are inherently 64-bit kernel only:
4eb0716e 28 select ARCH_HAS_GIGANTIC_PAGE
c12d3362 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
d94e0685
IM
30 select ARCH_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
f616ab59 33 select NEED_DMA_MAP_STATE
09230cbc 34 select SWIOTLB
7facdc42 35 select ARCH_HAS_ELFCORE_COMPAT
63703f37 36 select ZONE_DMA32
1032c0ba 37
518049d9
SRV
38config FORCE_DYNAMIC_FTRACE
39 def_bool y
40 depends on X86_32
41 depends on FUNCTION_TRACER
42 select DYNAMIC_FTRACE
43 help
758cd94a
JH
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
d94e0685
IM
49#
50# Arch settings
51#
52# ( Note that options that are marked 'if X86_64' could in principle be
53# ported to 32-bit as well. )
54#
8d5fffb9 55config X86
3c2362e6 56 def_bool y
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IM
57 #
58 # Note: keep this list sorted alphabetically
59 #
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IM
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
942fa985 62 select ARCH_32BIT_OFF_T if X86_32
2a21ad57 63 select ARCH_CLOCKSOURCE_INIT
1f6d3a8f 64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
1e866974 65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
5c11f00b 66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
91024b3c 67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
cebc774f 68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
1e866974 69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
c763ea26 70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
c2280be8 71 select ARCH_HAS_CACHE_LINE_SIZE
2792d84e 72 select ARCH_HAS_CURRENT_STACK_POINTER
fa5b6ec9 73 select ARCH_HAS_DEBUG_VIRTUAL
399145f9 74 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
21266be9 75 select ARCH_HAS_DEVMEM_IS_ALLOWED
b1a57bbf 76 select ARCH_HAS_EARLY_DEBUG if KGDB
6471b825 77 select ARCH_HAS_ELF_RANDOMIZE
72d93104 78 select ARCH_HAS_FAST_MULTIPLIER
6974f0c4 79 select ARCH_HAS_FORTIFY_SOURCE
957e3fac 80 select ARCH_HAS_GCOV_PROFILE_ALL
bece04b5 81 select ARCH_HAS_KCOV if X86_64
0c9c1d56 82 select ARCH_HAS_MEM_ENCRYPT
10bcc80e 83 select ARCH_HAS_MEMBARRIER_SYNC_CORE
0ebeea8c 84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
c763ea26 85 select ARCH_HAS_PMEM_API if X86_64
17596731 86 select ARCH_HAS_PTE_DEVMAP if X86_64
3010a5ea 87 select ARCH_HAS_PTE_SPECIAL
0aed55af 88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
ec6347bb 89 select ARCH_HAS_COPY_MC if X86_64
d2852a22 90 select ARCH_HAS_SET_MEMORY
d253ca0c 91 select ARCH_HAS_SET_DIRECT_MAP
ad21fc4f
LA
92 select ARCH_HAS_STRICT_KERNEL_RWX
93 select ARCH_HAS_STRICT_MODULE_RWX
ac1ab12a 94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
25c619e5 95 select ARCH_HAS_SYSCALL_WRAPPER
c6d30853 96 select ARCH_HAS_UBSAN_SANITIZE_ALL
e10cd4b0 97 select ARCH_HAS_VM_GET_PAGE_PROT
7e01ccb4 98 select ARCH_HAS_DEBUG_WX
63703f37 99 select ARCH_HAS_ZONE_DMA_SET if EXPERT
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IM
100 select ARCH_HAVE_NMI_SAFE_CMPXCHG
101 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
77fbbc81 102 select ARCH_MIGHT_HAVE_PC_PARPORT
5e2c18c0 103 select ARCH_MIGHT_HAVE_PC_SERIO
3599fe12 104 select ARCH_STACKWALK
2c870e61 105 select ARCH_SUPPORTS_ACPI
6471b825 106 select ARCH_SUPPORTS_ATOMIC_RMW
5d6ad668 107 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
d283d422 108 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
6471b825 109 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
14df3267 110 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
583bfd48
NC
111 select ARCH_SUPPORTS_LTO_CLANG
112 select ARCH_SUPPORTS_LTO_CLANG_THIN
6471b825 113 select ARCH_USE_BUILTIN_BSWAP
dce44566 114 select ARCH_USE_MEMTEST
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IM
115 select ARCH_USE_QUEUED_RWLOCKS
116 select ARCH_USE_QUEUED_SPINLOCKS
2ce0d7f9 117 select ARCH_USE_SYM_ANNOTATIONS
ce4a4e56 118 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
81c22041 119 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
c763ea26 120 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
51c2ee6d 121 select ARCH_WANTS_NO_INSTR
07431506 122 select ARCH_WANT_GENERAL_HUGETLB
3876d4a3 123 select ARCH_WANT_HUGE_PMD_SHARE
47010c04 124 select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
59612b24 125 select ARCH_WANT_LD_ORPHAN_WARN
38d8b4e6 126 select ARCH_WANTS_THP_SWAP if X86_64
b5f06f64 127 select ARCH_HAS_PARANOID_L1D_FLUSH
10916706 128 select BUILDTIME_TABLE_SORT
6471b825 129 select CLKEVT_I8253
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IM
130 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
131 select CLOCKSOURCE_WATCHDOG
6471b825 132 select DCACHE_WORD_ACCESS
3aac3ebe 133 select DYNAMIC_SIGFRAME
45471cd9
LT
134 select EDAC_ATOMIC_SCRUB
135 select EDAC_SUPPORT
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IM
136 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
137 select GENERIC_CLOCKEVENTS_MIN_ADJUST
138 select GENERIC_CMOS_UPDATE
139 select GENERIC_CPU_AUTOPROBE
61dc0f55 140 select GENERIC_CPU_VULNERABILITIES
5b7c73e0 141 select GENERIC_EARLY_IOREMAP
27d6b4d1 142 select GENERIC_ENTRY
6471b825 143 select GENERIC_IOMAP
c7d6c9dd 144 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
0fa115da 145 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
ad7a929f 146 select GENERIC_IRQ_MIGRATION if SMP
6471b825 147 select GENERIC_IRQ_PROBE
c201c917 148 select GENERIC_IRQ_RESERVATION_MODE
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IM
149 select GENERIC_IRQ_SHOW
150 select GENERIC_PENDING_IRQ if SMP
2ae27137 151 select GENERIC_PTDUMP
6471b825 152 select GENERIC_SMP_IDLE_THREAD
6471b825 153 select GENERIC_TIME_VSYSCALL
7ac87074 154 select GENERIC_GETTIMEOFDAY
550a77a7 155 select GENERIC_VDSO_TIME_NS
39656e83 156 select GUP_GET_PTE_LOW_HIGH if X86_PAE
17e5888e 157 select HARDIRQS_SW_RESEND
7edaeb68 158 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
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IM
159 select HAVE_ACPI_APEI if ACPI
160 select HAVE_ACPI_APEI_NMI if ACPI
161 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
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IM
162 select HAVE_ARCH_AUDITSYSCALL
163 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
eed1fcee 164 select HAVE_ARCH_HUGE_VMALLOC if X86_64
6471b825 165 select HAVE_ARCH_JUMP_LABEL
b34006c4 166 select HAVE_ARCH_JUMP_LABEL_RELATIVE
d17a1d97 167 select HAVE_ARCH_KASAN if X86_64
0609ae01 168 select HAVE_ARCH_KASAN_VMALLOC if X86_64
1dc0da6e 169 select HAVE_ARCH_KFENCE
6471b825 170 select HAVE_ARCH_KGDB
9e08f57d
DC
171 select HAVE_ARCH_MMAP_RND_BITS if MMU
172 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
1b028f78 173 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
271ca788 174 select HAVE_ARCH_PREL32_RELOCATIONS
6471b825 175 select HAVE_ARCH_SECCOMP_FILTER
f7d83c1c 176 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
afaef01c 177 select HAVE_ARCH_STACKLEAK
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IM
178 select HAVE_ARCH_TRACEHOOK
179 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
a00cc7d9 180 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
b64d8d1e 181 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
7677f7fd 182 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
e37e43a4 183 select HAVE_ARCH_VMAP_STACK if X86_64
fe950f60 184 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
c763ea26 185 select HAVE_ARCH_WITHIN_STACK_FRAMES
2ff2b7ec 186 select HAVE_ASM_MODVERSIONS
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IM
187 select HAVE_CMPXCHG_DOUBLE
188 select HAVE_CMPXCHG_LOCAL
189 select HAVE_CONTEXT_TRACKING if X86_64
d1f250e2 190 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
cf4db259 191 select HAVE_C_RECORDMCOUNT
03f16cd0 192 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
4ed308c4 193 select HAVE_BUILDTIME_MCOUNT_SORT
6471b825 194 select HAVE_DEBUG_KMEMLEAK
6471b825 195 select HAVE_DMA_CONTIGUOUS
677aa9f7 196 select HAVE_DYNAMIC_FTRACE
06aeaaea 197 select HAVE_DYNAMIC_FTRACE_WITH_REGS
02a474ca 198 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
562955fe 199 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
c316eb44 200 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
503e4510 201 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
03f5781b 202 select HAVE_EBPF_JIT
58340a07 203 select HAVE_EFFICIENT_UNALIGNED_ACCESS
6630a8e5 204 select HAVE_EISA
5f56a5df 205 select HAVE_EXIT_THREAD
67a929e0 206 select HAVE_FAST_GUP
644e0e8d 207 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
6471b825 208 select HAVE_FTRACE_MCOUNT_RECORD
4a30e4c9 209 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
6471b825 210 select HAVE_FUNCTION_TRACER
6b90bd4b 211 select HAVE_GCC_PLUGINS
6471b825 212 select HAVE_HW_BREAKPOINT
6471b825 213 select HAVE_IOREMAP_PROT
624db9ea 214 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
6471b825 215 select HAVE_IRQ_TIME_ACCOUNTING
4ab7674f 216 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
2e9f3bdd 217 select HAVE_KERNEL_BZIP2
6471b825
IM
218 select HAVE_KERNEL_GZIP
219 select HAVE_KERNEL_LZ4
2e9f3bdd 220 select HAVE_KERNEL_LZMA
13510997 221 select HAVE_KERNEL_LZO
6471b825 222 select HAVE_KERNEL_XZ
fb46d057 223 select HAVE_KERNEL_ZSTD
6471b825
IM
224 select HAVE_KPROBES
225 select HAVE_KPROBES_ON_FTRACE
540adea3 226 select HAVE_FUNCTION_ERROR_INJECTION
6471b825 227 select HAVE_KRETPROBES
f3a112c0 228 select HAVE_RETHOOK
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IM
229 select HAVE_KVM
230 select HAVE_LIVEPATCH if X86_64
0102752e 231 select HAVE_MIXED_BREAKPOINTS_REGS
ee9f8fce 232 select HAVE_MOD_ARCH_SPECIFIC
9f132f7e 233 select HAVE_MOVE_PMD
be37c98d 234 select HAVE_MOVE_PUD
22102f45 235 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
42a0bb3f 236 select HAVE_NMI
489e355b 237 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
03f16cd0 238 select HAVE_OBJTOOL if X86_64
6471b825
IM
239 select HAVE_OPTPROBES
240 select HAVE_PCSPKR_PLATFORM
241 select HAVE_PERF_EVENTS
c01d4323 242 select HAVE_PERF_EVENTS_NMI
92e5aae4 243 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
eb01d42a 244 select HAVE_PCI
c5e63197 245 select HAVE_PERF_REGS
c5ebcedb 246 select HAVE_PERF_USER_STACK_DUMP
03f16cd0 247 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
00998085 248 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
6471b825 249 select HAVE_REGS_AND_STACK_ACCESS_API
03f16cd0 250 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
3c88ee19 251 select HAVE_FUNCTION_ARG_ACCESS_API
7ecd19cf 252 select HAVE_SETUP_PER_CPU_AREA
cd1a41ce 253 select HAVE_SOFTIRQ_ON_OWN_STACK
d148eac0 254 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
03f16cd0 255 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
e6d6c071 256 select HAVE_STATIC_CALL
03f16cd0 257 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
99cf983c 258 select HAVE_PREEMPT_DYNAMIC_CALL
d6761b8f 259 select HAVE_RSEQ
6471b825 260 select HAVE_SYSCALL_TRACEPOINTS
5f3da8c0 261 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
6471b825 262 select HAVE_UNSTABLE_SCHED_CLOCK
7c68af6e 263 select HAVE_USER_RETURN_NOTIFIER
7ac87074 264 select HAVE_GENERIC_VDSO
05736e4a 265 select HOTPLUG_SMT if SMP
c0185808 266 select IRQ_FORCED_THREADING
7ecd19cf
KW
267 select NEED_PER_CPU_EMBED_FIRST_CHUNK
268 select NEED_PER_CPU_PAGE_FIRST_CHUNK
86596f0a 269 select NEED_SG_DMA_LENGTH
2eac9c2d 270 select PCI_DOMAINS if PCI
625210cf 271 select PCI_LOCKLESS_CONFIG if PCI
6471b825 272 select PERF_EVENTS
3195ef59 273 select RTC_LIB
d6faca40 274 select RTC_MC146818_LIB
6471b825 275 select SPARSE_IRQ
83fe27ea 276 select SRCU
6471b825 277 select SYSCTL_EXCEPTION_TRACE
15f4eae7 278 select THREAD_INFO_IN_TASK
4aae683f 279 select TRACE_IRQFLAGS_SUPPORT
6471b825
IM
280 select USER_STACKTRACE_SUPPORT
281 select VIRT_TO_BUS
3b02a051 282 select HAVE_ARCH_KCSAN if X86_64
6471b825 283 select X86_FEATURE_NAMES if PROC_FS
0c608dad 284 select PROC_PID_ARCH_STATUS if PROC_FS
50468e43 285 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
9e2b4be3 286 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
7d8330a5 287
ba7e4d13 288config INSTRUCTION_DECODER
3120e25e
JB
289 def_bool y
290 depends on KPROBES || PERF_EVENTS || UPROBES
ba7e4d13 291
51b26ada
LT
292config OUTPUT_FORMAT
293 string
294 default "elf32-i386" if X86_32
295 default "elf64-x86-64" if X86_64
296
8d5fffb9 297config LOCKDEP_SUPPORT
3c2362e6 298 def_bool y
8d5fffb9
SR
299
300config STACKTRACE_SUPPORT
3c2362e6 301 def_bool y
8d5fffb9 302
8d5fffb9 303config MMU
3c2362e6 304 def_bool y
8d5fffb9 305
9e08f57d
DC
306config ARCH_MMAP_RND_BITS_MIN
307 default 28 if 64BIT
308 default 8
309
310config ARCH_MMAP_RND_BITS_MAX
311 default 32 if 64BIT
312 default 16
313
314config ARCH_MMAP_RND_COMPAT_BITS_MIN
315 default 8
316
317config ARCH_MMAP_RND_COMPAT_BITS_MAX
318 default 16
319
8d5fffb9
SR
320config SBUS
321 bool
322
323config GENERIC_ISA_DMA
3120e25e
JB
324 def_bool y
325 depends on ISA_DMA_API
8d5fffb9 326
8d5fffb9 327config GENERIC_BUG
3c2362e6 328 def_bool y
8d5fffb9 329 depends on BUG
b93a531e
JB
330 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
331
332config GENERIC_BUG_RELATIVE_POINTERS
333 bool
8d5fffb9 334
8d5fffb9 335config ARCH_MAY_HAVE_PC_FDC
3120e25e
JB
336 def_bool y
337 depends on ISA_DMA_API
8d5fffb9 338
1032c0ba
SR
339config GENERIC_CALIBRATE_DELAY
340 def_bool y
341
9a0b8415 342config ARCH_HAS_CPU_RELAX
343 def_bool y
344
801e4062
JB
345config ARCH_HIBERNATION_POSSIBLE
346 def_bool y
801e4062 347
d7109fe3
AS
348config ARCH_NR_GPIO
349 int
350 default 1024 if X86_64
351 default 512
352
f4cb5700
JB
353config ARCH_SUSPEND_POSSIBLE
354 def_bool y
f4cb5700 355
8d5fffb9 356config AUDIT_ARCH
e0fd24a3 357 def_bool y if X86_64
8d5fffb9 358
d6f2d75a
AR
359config KASAN_SHADOW_OFFSET
360 hex
361 depends on KASAN
362 default 0xdffffc0000000000
363
69575d38
SW
364config HAVE_INTEL_TXT
365 def_bool y
6ea30386 366 depends on INTEL_IOMMU && ACPI
69575d38 367
6b0c3d44
SR
368config X86_32_SMP
369 def_bool y
370 depends on X86_32 && SMP
371
372config X86_64_SMP
373 def_bool y
374 depends on X86_64 && SMP
375
2b144498
SD
376config ARCH_SUPPORTS_UPROBES
377 def_bool y
378
d20642f0
RH
379config FIX_EARLYCON_MEM
380 def_bool y
381
94d49eb3
KS
382config DYNAMIC_PHYSICAL_MASK
383 bool
384
98233368
KS
385config PGTABLE_LEVELS
386 int
77ef56e4 387 default 5 if X86_5LEVEL
98233368
KS
388 default 4 if X86_64
389 default 3 if X86_PAE
390 default 2
391
2a61f474
MY
392config CC_HAS_SANE_STACKPROTECTOR
393 bool
394 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
395 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
396 help
758cd94a
JH
397 We have to make sure stack protector is unconditionally disabled if
398 the compiler produces broken code or if it does not let us control
399 the segment on 32-bit kernels.
2a61f474 400
506f1d07
SR
401menu "Processor type and features"
402
506f1d07
SR
403config SMP
404 bool "Symmetric multi-processing support"
a7f7f624 405 help
506f1d07 406 This enables support for systems with more than one CPU. If you have
4a474157
RG
407 a system with only one CPU, say N. If you have a system with more
408 than one CPU, say Y.
506f1d07 409
4a474157 410 If you say N here, the kernel will run on uni- and multiprocessor
506f1d07
SR
411 machines, but will use only one CPU of a multiprocessor machine. If
412 you say Y here, the kernel will run on many, but not all,
4a474157 413 uniprocessor machines. On a uniprocessor machine, the kernel
506f1d07
SR
414 will run faster if you say N here.
415
416 Note that if you say Y here and choose architecture "586" or
417 "Pentium" under "Processor family", the kernel will not work on 486
418 architectures. Similarly, multiprocessor kernels for the "PPro"
419 architecture may not work on all Pentium based boards.
420
421 People using multiprocessor machines who say Y here should also say
422 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
423 Management" code will be disabled if you say Y here.
424
cb1aaebe 425 See also <file:Documentation/x86/i386/IO-APIC.rst>,
4f4cfa6c 426 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
506f1d07
SR
427 <http://www.tldp.org/docs.html#howto>.
428
429 If you don't know what to do here, say N.
430
9def39be
JT
431config X86_FEATURE_NAMES
432 bool "Processor feature human-readable names" if EMBEDDED
433 default y
a7f7f624 434 help
9def39be
JT
435 This option compiles in a table of x86 feature bits and corresponding
436 names. This is required to support /proc/cpuinfo and a few kernel
437 messages. You can disable this to save space, at the expense of
438 making those few kernel messages show numeric feature bits instead.
439
440 If in doubt, say Y.
441
06cd9a7d
YL
442config X86_X2APIC
443 bool "Support x2apic"
19e3d60d 444 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
a7f7f624 445 help
06cd9a7d
YL
446 This enables x2apic support on CPUs that have this feature.
447
448 This allows 32-bit apic IDs (so it can support very large systems),
449 and accesses the local apic via MSRs not via mmio.
450
06cd9a7d
YL
451 If you don't know what to do here, say N.
452
6695c85b 453config X86_MPPARSE
4590d98f 454 bool "Enable MPS table" if ACPI
7a527688 455 default y
5ab74722 456 depends on X86_LOCAL_APIC
a7f7f624 457 help
6695c85b
YL
458 For old smp systems that do not have proper acpi support. Newer systems
459 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
6695c85b 460
ddd70cf9 461config GOLDFISH
b03b016f
KK
462 def_bool y
463 depends on X86_GOLDFISH
ddd70cf9 464
76b04384
DW
465config RETPOLINE
466 bool "Avoid speculative indirect branches in kernel"
03f16cd0 467 select OBJTOOL if HAVE_OBJTOOL
76b04384
DW
468 default y
469 help
470 Compile kernel with the retpoline compiler options to guard against
471 kernel-to-user data leaks by avoiding speculative indirect
472 branches. Requires a compiler with -mindirect-branch=thunk-extern
473 support for full protection. The kernel may run slower.
474
e463a09a
PZ
475config CC_HAS_SLS
476 def_bool $(cc-option,-mharden-sls=all)
477
478config SLS
479 bool "Mitigate Straight-Line-Speculation"
480 depends on CC_HAS_SLS && X86_64
03f16cd0 481 select OBJTOOL if HAVE_OBJTOOL
e463a09a
PZ
482 default n
483 help
484 Compile the kernel with straight-line-speculation options to guard
485 against straight line speculation. The kernel image might be slightly
486 larger.
487
e6d42931
JW
488config X86_CPU_RESCTRL
489 bool "x86 CPU resource control support"
6fe07ce3 490 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
59fe5a77 491 select KERNFS
e79f15a4 492 select PROC_CPU_RESCTRL if PROC_FS
78e99b4a 493 help
e6d42931 494 Enable x86 CPU resource control support.
6fe07ce3
BM
495
496 Provide support for the allocation and monitoring of system resources
497 usage by the CPU.
498
499 Intel calls this Intel Resource Director Technology
500 (Intel(R) RDT). More information about RDT can be found in the
501 Intel x86 Architecture Software Developer Manual.
502
503 AMD calls this AMD Platform Quality of Service (AMD QoS).
504 More information about AMD QoS can be found in the AMD64 Technology
505 Platform Quality of Service Extensions manual.
78e99b4a
FY
506
507 Say N if unsure.
508
8425091f 509if X86_32
a0d0bb4d
RD
510config X86_BIGSMP
511 bool "Support for big SMP systems with more than 8 CPUs"
512 depends on SMP
a7f7f624 513 help
e133f6ea 514 This option is needed for the systems that have more than 8 CPUs.
a0d0bb4d 515
c5c606d9
RT
516config X86_EXTENDED_PLATFORM
517 bool "Support for extended (non-PC) x86 platforms"
518 default y
a7f7f624 519 help
06ac8346
IM
520 If you disable this option then the kernel will only support
521 standard PC platforms. (which covers the vast majority of
522 systems out there.)
523
8425091f
RT
524 If you enable this option then you'll be able to select support
525 for the following (non-PC) 32 bit x86 platforms:
cb7b8023 526 Goldfish (Android emulator)
8425091f 527 AMD Elan
8425091f
RT
528 RDC R-321x SoC
529 SGI 320/540 (Visual Workstation)
83125a3a 530 STA2X11-based (e.g. Northville)
3f4110a4 531 Moorestown MID devices
06ac8346
IM
532
533 If you have one of these systems, or if you want to build a
534 generic distribution kernel, say Y here - otherwise say N.
758cd94a 535endif # X86_32
06ac8346 536
8425091f
RT
537if X86_64
538config X86_EXTENDED_PLATFORM
539 bool "Support for extended (non-PC) x86 platforms"
540 default y
a7f7f624 541 help
8425091f
RT
542 If you disable this option then the kernel will only support
543 standard PC platforms. (which covers the vast majority of
544 systems out there.)
545
546 If you enable this option then you'll be able to select support
547 for the following (non-PC) 64 bit x86 platforms:
44b111b5 548 Numascale NumaChip
8425091f
RT
549 ScaleMP vSMP
550 SGI Ultraviolet
551
552 If you have one of these systems, or if you want to build a
553 generic distribution kernel, say Y here - otherwise say N.
758cd94a 554endif # X86_64
c5c606d9
RT
555# This is an alphabetically sorted list of 64 bit extended platforms
556# Please maintain the alphabetic order if and when there are additions
44b111b5
SP
557config X86_NUMACHIP
558 bool "Numascale NumaChip"
559 depends on X86_64
560 depends on X86_EXTENDED_PLATFORM
561 depends on NUMA
562 depends on SMP
563 depends on X86_X2APIC
f9726bfd 564 depends on PCI_MMCONFIG
a7f7f624 565 help
44b111b5
SP
566 Adds support for Numascale NumaChip large-SMP systems. Needed to
567 enable more than ~168 cores.
568 If you don't have one of these, you should say N here.
506f1d07 569
c5c606d9
RT
570config X86_VSMP
571 bool "ScaleMP vSMP"
6276a074 572 select HYPERVISOR_GUEST
c5c606d9
RT
573 select PARAVIRT
574 depends on X86_64 && PCI
575 depends on X86_EXTENDED_PLATFORM
ead91d4b 576 depends on SMP
a7f7f624 577 help
c5c606d9
RT
578 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
579 supposed to run on these EM64T-based machines. Only choose this option
580 if you have one of these machines.
5e3a77e9 581
03b48632
NP
582config X86_UV
583 bool "SGI Ultraviolet"
584 depends on X86_64
c5c606d9 585 depends on X86_EXTENDED_PLATFORM
54c28d29 586 depends on NUMA
1ecb4ae5 587 depends on EFI
c2209ea5 588 depends on KEXEC_CORE
9d6c26e7 589 depends on X86_X2APIC
1222e564 590 depends on PCI
a7f7f624 591 help
03b48632
NP
592 This option is needed in order to support SGI Ultraviolet systems.
593 If you don't have one of these, you should say N here.
594
c5c606d9
RT
595# Following is an alphabetically sorted list of 32 bit extended platforms
596# Please maintain the alphabetic order if and when there are additions
506f1d07 597
ddd70cf9 598config X86_GOLDFISH
b03b016f
KK
599 bool "Goldfish (Virtual Platform)"
600 depends on X86_EXTENDED_PLATFORM
a7f7f624 601 help
758cd94a
JH
602 Enable support for the Goldfish virtual platform used primarily
603 for Android development. Unless you are building for the Android
604 Goldfish emulator say N here.
ddd70cf9 605
c751e17b
TG
606config X86_INTEL_CE
607 bool "CE4100 TV platform"
608 depends on PCI
609 depends on PCI_GODIRECT
6084a6e2 610 depends on X86_IO_APIC
c751e17b
TG
611 depends on X86_32
612 depends on X86_EXTENDED_PLATFORM
37bc9f50 613 select X86_REBOOTFIXUPS
da6b737b
SAS
614 select OF
615 select OF_EARLY_FLATTREE
a7f7f624 616 help
c751e17b
TG
617 Select for the Intel CE media processor (CE4100) SOC.
618 This option compiles in support for the CE4100 SOC for settop
619 boxes and media devices.
620
4cb9b00f 621config X86_INTEL_MID
43605ef1 622 bool "Intel MID platform support"
43605ef1 623 depends on X86_EXTENDED_PLATFORM
edc6bc78 624 depends on X86_PLATFORM_DEVICES
1ea7c673 625 depends on PCI
3fda5bb4 626 depends on X86_64 || (PCI_GOANY && X86_32)
1ea7c673 627 depends on X86_IO_APIC
4cb9b00f 628 select I2C
7c9c3a1e 629 select DW_APB_TIMER
54b34aa0 630 select INTEL_SCU_PCI
a7f7f624 631 help
4cb9b00f
DC
632 Select to build a kernel capable of supporting Intel MID (Mobile
633 Internet Device) platform systems which do not have the PCI legacy
634 interfaces. If you are building for a PC class system say N here.
1ea7c673 635
4cb9b00f
DC
636 Intel MID platforms are based on an Intel processor and chipset which
637 consume less power than most of the x86 derivatives.
43605ef1 638
8bbc2a13
BD
639config X86_INTEL_QUARK
640 bool "Intel Quark platform support"
641 depends on X86_32
642 depends on X86_EXTENDED_PLATFORM
643 depends on X86_PLATFORM_DEVICES
644 depends on X86_TSC
645 depends on PCI
646 depends on PCI_GOANY
647 depends on X86_IO_APIC
648 select IOSF_MBI
649 select INTEL_IMR
9ab6eb51 650 select COMMON_CLK
a7f7f624 651 help
8bbc2a13
BD
652 Select to include support for Quark X1000 SoC.
653 Say Y here if you have a Quark based system such as the Arduino
654 compatible Intel Galileo.
655
3d48aab1
MW
656config X86_INTEL_LPSS
657 bool "Intel Low Power Subsystem Support"
5962dd22 658 depends on X86 && ACPI && PCI
3d48aab1 659 select COMMON_CLK
0f531431 660 select PINCTRL
eebb3e8d 661 select IOSF_MBI
a7f7f624 662 help
3d48aab1
MW
663 Select to build support for Intel Low Power Subsystem such as
664 found on Intel Lynxpoint PCH. Selecting this option enables
0f531431
MN
665 things like clock tree (common clock framework) and pincontrol
666 which are needed by the LPSS peripheral drivers.
3d48aab1 667
92082a88
KX
668config X86_AMD_PLATFORM_DEVICE
669 bool "AMD ACPI2Platform devices support"
670 depends on ACPI
671 select COMMON_CLK
672 select PINCTRL
a7f7f624 673 help
92082a88
KX
674 Select to interpret AMD specific ACPI device to platform device
675 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
676 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
677 implemented under PINCTRL subsystem.
678
ced3ce76
DB
679config IOSF_MBI
680 tristate "Intel SoC IOSF Sideband support for SoC platforms"
681 depends on PCI
a7f7f624 682 help
ced3ce76
DB
683 This option enables sideband register access support for Intel SoC
684 platforms. On these platforms the IOSF sideband is used in lieu of
685 MSR's for some register accesses, mostly but not limited to thermal
686 and power. Drivers may query the availability of this device to
687 determine if they need the sideband in order to work on these
688 platforms. The sideband is available on the following SoC products.
689 This list is not meant to be exclusive.
690 - BayTrail
691 - Braswell
692 - Quark
693
694 You should say Y if you are running a kernel on one of these SoC's.
695
ed2226bd
DB
696config IOSF_MBI_DEBUG
697 bool "Enable IOSF sideband access through debugfs"
698 depends on IOSF_MBI && DEBUG_FS
a7f7f624 699 help
ed2226bd
DB
700 Select this option to expose the IOSF sideband access registers (MCR,
701 MDR, MCRX) through debugfs to write and read register information from
702 different units on the SoC. This is most useful for obtaining device
703 state information for debug and analysis. As this is a general access
704 mechanism, users of this option would have specific knowledge of the
705 device they want to access.
706
707 If you don't require the option or are in doubt, say N.
708
c5c606d9
RT
709config X86_RDC321X
710 bool "RDC R-321x SoC"
506f1d07 711 depends on X86_32
c5c606d9
RT
712 depends on X86_EXTENDED_PLATFORM
713 select M486
714 select X86_REBOOTFIXUPS
a7f7f624 715 help
c5c606d9
RT
716 This option is needed for RDC R-321x system-on-chip, also known
717 as R-8610-(G).
718 If you don't have one of these chips, you should say N here.
719
e0c7ae37 720config X86_32_NON_STANDARD
9c398017
IM
721 bool "Support non-standard 32-bit SMP architectures"
722 depends on X86_32 && SMP
c5c606d9 723 depends on X86_EXTENDED_PLATFORM
a7f7f624 724 help
b5660ba7
PA
725 This option compiles in the bigsmp and STA2X11 default
726 subarchitectures. It is intended for a generic binary
727 kernel. If you select them all, kernel will probe it one by
728 one and will fallback to default.
d49c4288 729
c5c606d9 730# Alphabetically sorted list of Non standard 32 bit platforms
d49c4288 731
d949f36f 732config X86_SUPPORTS_MEMORY_FAILURE
6fc108a0 733 def_bool y
d949f36f
LT
734 # MCE code calls memory_failure():
735 depends on X86_MCE
736 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
d949f36f
LT
737 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
738 depends on X86_64 || !SPARSEMEM
739 select ARCH_SUPPORTS_MEMORY_FAILURE
d949f36f 740
83125a3a
AR
741config STA2X11
742 bool "STA2X11 Companion Chip Support"
743 depends on X86_32_NON_STANDARD && PCI
83125a3a
AR
744 select SWIOTLB
745 select MFD_STA2X11
0145071b 746 select GPIOLIB
a7f7f624 747 help
83125a3a
AR
748 This adds support for boards based on the STA2X11 IO-Hub,
749 a.k.a. "ConneXt". The chip is used in place of the standard
750 PC chipset, so all "standard" peripherals are missing. If this
751 option is selected the kernel will still be able to boot on
752 standard PC machines.
753
82148d1d
S
754config X86_32_IRIS
755 tristate "Eurobraille/Iris poweroff module"
756 depends on X86_32
a7f7f624 757 help
82148d1d
S
758 The Iris machines from EuroBraille do not have APM or ACPI support
759 to shut themselves down properly. A special I/O sequence is
760 needed to do so, which is what this module does at
761 kernel shutdown.
762
763 This is only for Iris machines from EuroBraille.
764
765 If unused, say N.
766
ae1e9130 767config SCHED_OMIT_FRAME_POINTER
3c2362e6
HH
768 def_bool y
769 prompt "Single-depth WCHAN output"
a87d0914 770 depends on X86
a7f7f624 771 help
506f1d07
SR
772 Calculate simpler /proc/<PID>/wchan values. If this option
773 is disabled then wchan values will recurse back to the
774 caller function. This provides more accurate wchan values,
775 at the expense of slightly more scheduling overhead.
776
777 If in doubt, say "Y".
778
6276a074
BP
779menuconfig HYPERVISOR_GUEST
780 bool "Linux guest support"
a7f7f624 781 help
6276a074
BP
782 Say Y here to enable options for running Linux under various hyper-
783 visors. This option enables basic hypervisor detection and platform
784 setup.
506f1d07 785
6276a074
BP
786 If you say N, all options in this submenu will be skipped and
787 disabled, and Linux guest support won't be built in.
506f1d07 788
6276a074 789if HYPERVISOR_GUEST
506f1d07 790
e61bd94a
EPH
791config PARAVIRT
792 bool "Enable paravirtualization code"
a0e2bf7c 793 depends on HAVE_STATIC_CALL
a7f7f624 794 help
e61bd94a
EPH
795 This changes the kernel so it can modify itself when it is run
796 under a hypervisor, potentially improving performance significantly
797 over full virtualization. However, when run without a hypervisor
798 the kernel is theoretically slower and slightly larger.
799
c00a280a
JG
800config PARAVIRT_XXL
801 bool
802
6276a074
BP
803config PARAVIRT_DEBUG
804 bool "paravirt-ops debugging"
805 depends on PARAVIRT && DEBUG_KERNEL
a7f7f624 806 help
6276a074
BP
807 Enable to debug paravirt_ops internals. Specifically, BUG if
808 a paravirt_op is missing when it is called.
809
b4ecc126
JF
810config PARAVIRT_SPINLOCKS
811 bool "Paravirtualization layer for spinlocks"
6ea30386 812 depends on PARAVIRT && SMP
a7f7f624 813 help
b4ecc126
JF
814 Paravirtualized spinlocks allow a pvops backend to replace the
815 spinlock implementation with something virtualization-friendly
816 (for example, block the virtual CPU rather than spinning).
817
4c4e4f61
R
818 It has a minimal impact on native kernels and gives a nice performance
819 benefit on paravirtualized KVM / Xen kernels.
b4ecc126 820
4c4e4f61 821 If you are unsure how to answer this question, answer Y.
b4ecc126 822
ecca2502
ZY
823config X86_HV_CALLBACK_VECTOR
824 def_bool n
825
6276a074 826source "arch/x86/xen/Kconfig"
7af192c9 827
6276a074
BP
828config KVM_GUEST
829 bool "KVM Guest support (including kvmclock)"
830 depends on PARAVIRT
831 select PARAVIRT_CLOCK
a1c4423b 832 select ARCH_CPUIDLE_HALTPOLL
b1d40575 833 select X86_HV_CALLBACK_VECTOR
6276a074 834 default y
a7f7f624 835 help
6276a074
BP
836 This option enables various optimizations for running under the KVM
837 hypervisor. It includes a paravirtualized clock, so that instead
838 of relying on a PIT (or probably other) emulation by the
839 underlying device model, the host provides the guest with
840 timing infrastructure such as time of day, and system time
506f1d07 841
a1c4423b 842config ARCH_CPUIDLE_HALTPOLL
b03b016f
KK
843 def_bool n
844 prompt "Disable host haltpoll when loading haltpoll driver"
845 help
a1c4423b
MT
846 If virtualized under KVM, disable host haltpoll.
847
7733607f
MW
848config PVH
849 bool "Support for running PVH guests"
a7f7f624 850 help
7733607f
MW
851 This option enables the PVH entry point for guest virtual machines
852 as specified in the x86/HVM direct boot ABI.
853
6276a074
BP
854config PARAVIRT_TIME_ACCOUNTING
855 bool "Paravirtual steal time accounting"
856 depends on PARAVIRT
a7f7f624 857 help
6276a074
BP
858 Select this option to enable fine granularity task steal time
859 accounting. Time spent executing other tasks in parallel with
860 the current vCPU is discounted from the vCPU power. To account for
861 that, there can be a small performance impact.
862
863 If in doubt, say N here.
864
865config PARAVIRT_CLOCK
866 bool
97349135 867
4a362601
JK
868config JAILHOUSE_GUEST
869 bool "Jailhouse non-root cell support"
abde587b 870 depends on X86_64 && PCI
87e65d05 871 select X86_PM_TIMER
a7f7f624 872 help
4a362601
JK
873 This option allows to run Linux as guest in a Jailhouse non-root
874 cell. You can leave this option disabled if you only want to start
875 Jailhouse and run Linux afterwards in the root cell.
876
ec7972c9
ZY
877config ACRN_GUEST
878 bool "ACRN Guest support"
879 depends on X86_64
498ad393 880 select X86_HV_CALLBACK_VECTOR
ec7972c9
ZY
881 help
882 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
883 a flexible, lightweight reference open-source hypervisor, built with
884 real-time and safety-criticality in mind. It is built for embedded
885 IOT with small footprint and real-time features. More details can be
886 found in https://projectacrn.org/.
887
59bd54a8
KS
888config INTEL_TDX_GUEST
889 bool "Intel TDX (Trust Domain Extensions) - Guest Support"
890 depends on X86_64 && CPU_SUP_INTEL
891 depends on X86_X2APIC
41394e33 892 select ARCH_HAS_CC_PLATFORM
968b4931 893 select X86_MEM_ENCRYPT
77a512e3 894 select X86_MCE
59bd54a8
KS
895 help
896 Support running as a guest under Intel TDX. Without this support,
897 the guest kernel can not boot or run under TDX.
898 TDX includes memory encryption and integrity capabilities
899 which protect the confidentiality and integrity of guest
900 memory contents and CPU state. TDX guests are protected from
901 some attacks from the VMM.
902
758cd94a 903endif # HYPERVISOR_GUEST
97349135 904
506f1d07
SR
905source "arch/x86/Kconfig.cpu"
906
907config HPET_TIMER
3c2362e6 908 def_bool X86_64
506f1d07 909 prompt "HPET Timer Support" if X86_32
a7f7f624 910 help
8f9ca475
IM
911 Use the IA-PC HPET (High Precision Event Timer) to manage
912 time in preference to the PIT and RTC, if a HPET is
913 present.
914 HPET is the next generation timer replacing legacy 8254s.
915 The HPET provides a stable time base on SMP
916 systems, unlike the TSC, but it is more expensive to access,
4e7f9df2
MT
917 as it is off-chip. The interface used is documented
918 in the HPET spec, revision 1.
506f1d07 919
8f9ca475
IM
920 You can safely choose Y here. However, HPET will only be
921 activated if the platform and the BIOS support this feature.
922 Otherwise the 8254 will be used for timing services.
506f1d07 923
8f9ca475 924 Choose N to continue using the legacy 8254 timer.
506f1d07
SR
925
926config HPET_EMULATE_RTC
3c2362e6 927 def_bool y
3228e1dc 928 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
506f1d07 929
6a108a14 930# Mark as expert because too many people got it wrong.
506f1d07 931# The code disables itself when not needed.
7ae9392c
TP
932config DMI
933 default y
cf074402 934 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
6a108a14 935 bool "Enable DMI scanning" if EXPERT
a7f7f624 936 help
7ae9392c
TP
937 Enabled scanning of DMI to identify machine quirks. Say Y
938 here unless you have verified that your setup is not
939 affected by entries in the DMI blacklist. Required by PNP
940 BIOS code.
941
506f1d07 942config GART_IOMMU
38901f1c 943 bool "Old AMD GART IOMMU support"
2f9237d4 944 select DMA_OPS
a4ce5a48 945 select IOMMU_HELPER
506f1d07 946 select SWIOTLB
23ac4ae8 947 depends on X86_64 && PCI && AMD_NB
a7f7f624 948 help
ced3c42c
IM
949 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
950 GART based hardware IOMMUs.
951
952 The GART supports full DMA access for devices with 32-bit access
953 limitations, on systems with more than 3 GB. This is usually needed
954 for USB, sound, many IDE/SATA chipsets and some other devices.
955
956 Newer systems typically have a modern AMD IOMMU, supported via
957 the CONFIG_AMD_IOMMU=y config option.
958
959 In normal configurations this driver is only active when needed:
960 there's more than 3 GB of memory and the system contains a
961 32-bit limited device.
962
963 If unsure, say Y.
506f1d07 964
8b766b0f
MS
965config BOOT_VESA_SUPPORT
966 bool
967 help
968 If true, at least one selected framebuffer driver can take advantage
969 of VESA video modes set at an early boot stage via the vga= parameter.
506f1d07 970
1184dc2f 971config MAXSMP
ddb0c5a6 972 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
6ea30386 973 depends on X86_64 && SMP && DEBUG_KERNEL
36f5101a 974 select CPUMASK_OFFSTACK
a7f7f624 975 help
ddb0c5a6 976 Enable maximum number of CPUS and NUMA Nodes for this architecture.
1184dc2f 977 If unsure, say N.
506f1d07 978
aec6487e
IM
979#
980# The maximum number of CPUs supported:
981#
982# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
983# and which can be configured interactively in the
984# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
985#
986# The ranges are different on 32-bit and 64-bit kernels, depending on
987# hardware capabilities and scalability features of the kernel.
988#
989# ( If MAXSMP is enabled we just use the highest possible value and disable
990# interactive configuration. )
991#
992
993config NR_CPUS_RANGE_BEGIN
a0d0bb4d 994 int
aec6487e
IM
995 default NR_CPUS_RANGE_END if MAXSMP
996 default 1 if !SMP
997 default 2
a0d0bb4d 998
aec6487e 999config NR_CPUS_RANGE_END
a0d0bb4d 1000 int
aec6487e
IM
1001 depends on X86_32
1002 default 64 if SMP && X86_BIGSMP
1003 default 8 if SMP && !X86_BIGSMP
1004 default 1 if !SMP
a0d0bb4d 1005
aec6487e 1006config NR_CPUS_RANGE_END
a0d0bb4d 1007 int
aec6487e 1008 depends on X86_64
1edae1ae
SW
1009 default 8192 if SMP && CPUMASK_OFFSTACK
1010 default 512 if SMP && !CPUMASK_OFFSTACK
aec6487e 1011 default 1 if !SMP
a0d0bb4d 1012
aec6487e 1013config NR_CPUS_DEFAULT
a0d0bb4d
RD
1014 int
1015 depends on X86_32
aec6487e
IM
1016 default 32 if X86_BIGSMP
1017 default 8 if SMP
1018 default 1 if !SMP
a0d0bb4d 1019
aec6487e 1020config NR_CPUS_DEFAULT
a0d0bb4d
RD
1021 int
1022 depends on X86_64
aec6487e
IM
1023 default 8192 if MAXSMP
1024 default 64 if SMP
1025 default 1 if !SMP
a0d0bb4d 1026
506f1d07 1027config NR_CPUS
36f5101a 1028 int "Maximum number of CPUs" if SMP && !MAXSMP
aec6487e
IM
1029 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1030 default NR_CPUS_DEFAULT
a7f7f624 1031 help
506f1d07 1032 This allows you to specify the maximum number of CPUs which this
bb61ccc7 1033 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
cad14bb9 1034 supported value is 8192, otherwise the maximum value is 512. The
506f1d07
SR
1035 minimum value which makes sense is 2.
1036
aec6487e
IM
1037 This is purely to save memory: each supported CPU adds about 8KB
1038 to the kernel image.
506f1d07 1039
66558b73
TC
1040config SCHED_CLUSTER
1041 bool "Cluster scheduler support"
1042 depends on SMP
1043 default y
1044 help
1045 Cluster scheduler support improves the CPU scheduler's decision
1046 making when dealing with machines that have clusters of CPUs.
1047 Cluster usually means a couple of CPUs which are placed closely
1048 by sharing mid-level caches, last-level cache tags or internal
1049 busses.
1050
506f1d07 1051config SCHED_SMT
dbe73364 1052 def_bool y if SMP
506f1d07
SR
1053
1054config SCHED_MC
3c2362e6
HH
1055 def_bool y
1056 prompt "Multi-core scheduler support"
c8e56d20 1057 depends on SMP
a7f7f624 1058 help
506f1d07
SR
1059 Multi-core scheduler support improves the CPU scheduler's decision
1060 making when dealing with multi-core CPU chips at a cost of slightly
1061 increased overhead in some places. If unsure say N here.
1062
de966cf4
TC
1063config SCHED_MC_PRIO
1064 bool "CPU core priorities scheduler support"
0a21fc12
IM
1065 depends on SCHED_MC && CPU_SUP_INTEL
1066 select X86_INTEL_PSTATE
1067 select CPU_FREQ
de966cf4 1068 default y
a7f7f624 1069 help
0a21fc12
IM
1070 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1071 core ordering determined at manufacturing time, which allows
1072 certain cores to reach higher turbo frequencies (when running
1073 single threaded workloads) than others.
de966cf4 1074
0a21fc12
IM
1075 Enabling this kernel feature teaches the scheduler about
1076 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1077 scheduler's CPU selection logic accordingly, so that higher
1078 overall system performance can be achieved.
de966cf4 1079
0a21fc12 1080 This feature will have no effect on CPUs without this feature.
de966cf4 1081
0a21fc12 1082 If unsure say Y here.
5e76b2ab 1083
30b8b006 1084config UP_LATE_INIT
b03b016f
KK
1085 def_bool y
1086 depends on !SMP && X86_LOCAL_APIC
30b8b006 1087
506f1d07 1088config X86_UP_APIC
50849eef
JB
1089 bool "Local APIC support on uniprocessors" if !PCI_MSI
1090 default PCI_MSI
38a1dfda 1091 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
a7f7f624 1092 help
506f1d07
SR
1093 A local APIC (Advanced Programmable Interrupt Controller) is an
1094 integrated interrupt controller in the CPU. If you have a single-CPU
1095 system which has a processor with a local APIC, you can say Y here to
1096 enable and use it. If you say Y here even though your machine doesn't
1097 have a local APIC, then the kernel will still run with no slowdown at
1098 all. The local APIC supports CPU-generated self-interrupts (timer,
1099 performance counters), and the NMI watchdog which detects hard
1100 lockups.
1101
1102config X86_UP_IOAPIC
1103 bool "IO-APIC support on uniprocessors"
1104 depends on X86_UP_APIC
a7f7f624 1105 help
506f1d07
SR
1106 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1107 SMP-capable replacement for PC-style interrupt controllers. Most
1108 SMP systems and many recent uniprocessor systems have one.
1109
1110 If you have a single-CPU system with an IO-APIC, you can say Y here
1111 to use it. If you say Y here even though your machine doesn't have
1112 an IO-APIC, then the kernel will still run with no slowdown at all.
1113
1114config X86_LOCAL_APIC
3c2362e6 1115 def_bool y
0dbc6078 1116 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
b5dc8e6c 1117 select IRQ_DOMAIN_HIERARCHY
52f518a3 1118 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
506f1d07
SR
1119
1120config X86_IO_APIC
b1da1e71
JB
1121 def_bool y
1122 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
506f1d07 1123
41b9eb26
SA
1124config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1125 bool "Reroute for broken boot IRQs"
41b9eb26 1126 depends on X86_IO_APIC
a7f7f624 1127 help
41b9eb26
SA
1128 This option enables a workaround that fixes a source of
1129 spurious interrupts. This is recommended when threaded
1130 interrupt handling is used on systems where the generation of
1131 superfluous "boot interrupts" cannot be disabled.
1132
1133 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1134 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1135 kernel does during interrupt handling). On chipsets where this
1136 boot IRQ generation cannot be disabled, this workaround keeps
1137 the original IRQ line masked so that only the equivalent "boot
1138 IRQ" is delivered to the CPUs. The workaround also tells the
1139 kernel to set up the IRQ handler on the boot IRQ line. In this
1140 way only one interrupt is delivered to the kernel. Otherwise
1141 the spurious second interrupt may cause the kernel to bring
1142 down (vital) interrupt lines.
1143
1144 Only affects "broken" chipsets. Interrupt sharing may be
1145 increased on these systems.
1146
506f1d07 1147config X86_MCE
bab9bc65 1148 bool "Machine Check / overheating reporting"
648ed940 1149 select GENERIC_ALLOCATOR
e57dbaf7 1150 default y
a7f7f624 1151 help
bab9bc65
AK
1152 Machine Check support allows the processor to notify the
1153 kernel if it detects a problem (e.g. overheating, data corruption).
506f1d07 1154 The action the kernel takes depends on the severity of the problem,
bab9bc65 1155 ranging from warning messages to halting the machine.
4efc0670 1156
5de97c9f
TL
1157config X86_MCELOG_LEGACY
1158 bool "Support for deprecated /dev/mcelog character device"
1159 depends on X86_MCE
a7f7f624 1160 help
5de97c9f
TL
1161 Enable support for /dev/mcelog which is needed by the old mcelog
1162 userspace logging daemon. Consider switching to the new generation
1163 rasdaemon solution.
1164
506f1d07 1165config X86_MCE_INTEL
3c2362e6
HH
1166 def_bool y
1167 prompt "Intel MCE features"
c1ebf835 1168 depends on X86_MCE && X86_LOCAL_APIC
a7f7f624 1169 help
758cd94a
JH
1170 Additional support for intel specific MCE features such as
1171 the thermal monitor.
506f1d07
SR
1172
1173config X86_MCE_AMD
3c2362e6
HH
1174 def_bool y
1175 prompt "AMD MCE features"
f5382de9 1176 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
a7f7f624 1177 help
758cd94a
JH
1178 Additional support for AMD specific MCE features such as
1179 the DRAM Error Threshold.
506f1d07 1180
4efc0670 1181config X86_ANCIENT_MCE
6fc108a0 1182 bool "Support for old Pentium 5 / WinChip machine checks"
c31d9633 1183 depends on X86_32 && X86_MCE
a7f7f624 1184 help
cd13adcc 1185 Include support for machine check handling on old Pentium 5 or WinChip
5065a706 1186 systems. These typically need to be enabled explicitly on the command
cd13adcc 1187 line.
4efc0670 1188
b2762686
AK
1189config X86_MCE_THRESHOLD
1190 depends on X86_MCE_AMD || X86_MCE_INTEL
6fc108a0 1191 def_bool y
b2762686 1192
ea149b36 1193config X86_MCE_INJECT
bc8e80d5 1194 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
ea149b36 1195 tristate "Machine check injector support"
a7f7f624 1196 help
ea149b36
AK
1197 Provide support for injecting machine checks for testing purposes.
1198 If you don't know what a machine check is and you don't do kernel
1199 QA it is safe to say n.
1200
07dc900e 1201source "arch/x86/events/Kconfig"
e633c65a 1202
5aef51c3 1203config X86_LEGACY_VM86
1e642812 1204 bool "Legacy VM86 support"
506f1d07 1205 depends on X86_32
a7f7f624 1206 help
5aef51c3
AL
1207 This option allows user programs to put the CPU into V8086
1208 mode, which is an 80286-era approximation of 16-bit real mode.
1209
1210 Some very old versions of X and/or vbetool require this option
1211 for user mode setting. Similarly, DOSEMU will use it if
1212 available to accelerate real mode DOS programs. However, any
1213 recent version of DOSEMU, X, or vbetool should be fully
1214 functional even without kernel VM86 support, as they will all
1e642812
IM
1215 fall back to software emulation. Nevertheless, if you are using
1216 a 16-bit DOS program where 16-bit performance matters, vm86
1217 mode might be faster than emulation and you might want to
1218 enable this option.
5aef51c3 1219
1e642812
IM
1220 Note that any app that works on a 64-bit kernel is unlikely to
1221 need this option, as 64-bit kernels don't, and can't, support
1222 V8086 mode. This option is also unrelated to 16-bit protected
1223 mode and is not needed to run most 16-bit programs under Wine.
5aef51c3 1224
1e642812
IM
1225 Enabling this option increases the complexity of the kernel
1226 and slows down exception handling a tiny bit.
5aef51c3 1227
1e642812 1228 If unsure, say N here.
5aef51c3
AL
1229
1230config VM86
b03b016f
KK
1231 bool
1232 default X86_LEGACY_VM86
34273f41
PA
1233
1234config X86_16BIT
1235 bool "Enable support for 16-bit segments" if EXPERT
1236 default y
a5b9e5a2 1237 depends on MODIFY_LDT_SYSCALL
a7f7f624 1238 help
34273f41
PA
1239 This option is required by programs like Wine to run 16-bit
1240 protected mode legacy code on x86 processors. Disabling
1241 this option saves about 300 bytes on i386, or around 6K text
1242 plus 16K runtime memory on x86-64,
1243
1244config X86_ESPFIX32
1245 def_bool y
1246 depends on X86_16BIT && X86_32
506f1d07 1247
197725de
PA
1248config X86_ESPFIX64
1249 def_bool y
34273f41 1250 depends on X86_16BIT && X86_64
506f1d07 1251
1ad83c85 1252config X86_VSYSCALL_EMULATION
b03b016f
KK
1253 bool "Enable vsyscall emulation" if EXPERT
1254 default y
1255 depends on X86_64
a7f7f624 1256 help
758cd94a
JH
1257 This enables emulation of the legacy vsyscall page. Disabling
1258 it is roughly equivalent to booting with vsyscall=none, except
1259 that it will also disable the helpful warning if a program
1260 tries to use a vsyscall. With this option set to N, offending
1261 programs will just segfault, citing addresses of the form
1262 0xffffffffff600?00.
1ad83c85 1263
758cd94a
JH
1264 This option is required by many programs built before 2013, and
1265 care should be used even with newer programs if set to N.
1ad83c85 1266
758cd94a
JH
1267 Disabling this option saves about 7K of kernel size and
1268 possibly 4K of additional runtime pagetable memory.
1ad83c85 1269
111e7b15
TG
1270config X86_IOPL_IOPERM
1271 bool "IOPERM and IOPL Emulation"
a24ca997 1272 default y
a7f7f624 1273 help
111e7b15
TG
1274 This enables the ioperm() and iopl() syscalls which are necessary
1275 for legacy applications.
1276
c8137ace
TG
1277 Legacy IOPL support is an overbroad mechanism which allows user
1278 space aside of accessing all 65536 I/O ports also to disable
1279 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1280 capabilities and permission from potentially active security
1281 modules.
1282
1283 The emulation restricts the functionality of the syscall to
1284 only allowing the full range I/O port access, but prevents the
a24ca997
TG
1285 ability to disable interrupts from user space which would be
1286 granted if the hardware IOPL mechanism would be used.
c8137ace 1287
506f1d07
SR
1288config TOSHIBA
1289 tristate "Toshiba Laptop support"
1290 depends on X86_32
a7f7f624 1291 help
506f1d07
SR
1292 This adds a driver to safely access the System Management Mode of
1293 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1294 not work on models with a Phoenix BIOS. The System Management Mode
1295 is used to set the BIOS and power saving options on Toshiba portables.
1296
1297 For information on utilities to make use of this driver see the
1298 Toshiba Linux utilities web site at:
1299 <http://www.buzzard.org.uk/toshiba/>.
1300
1301 Say Y if you intend to run this kernel on a Toshiba portable.
1302 Say N otherwise.
1303
506f1d07 1304config X86_REBOOTFIXUPS
9ba16087
JB
1305 bool "Enable X86 board specific fixups for reboot"
1306 depends on X86_32
a7f7f624 1307 help
506f1d07
SR
1308 This enables chipset and/or board specific fixups to be done
1309 in order to get reboot to work correctly. This is only needed on
1310 some combinations of hardware and BIOS. The symptom, for which
1311 this config is intended, is when reboot ends with a stalled/hung
1312 system.
1313
1314 Currently, the only fixup is for the Geode machines using
5e3a77e9 1315 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
506f1d07
SR
1316
1317 Say Y if you want to enable the fixup. Currently, it's safe to
1318 enable this option even if you don't need it.
1319 Say N otherwise.
1320
1321config MICROCODE
9a2bc335
BP
1322 bool "CPU microcode loading support"
1323 default y
80030e3d 1324 depends on CPU_SUP_AMD || CPU_SUP_INTEL
a7f7f624 1325 help
506f1d07 1326 If you say Y here, you will be able to update the microcode on
5f9c01aa
BP
1327 Intel and AMD processors. The Intel support is for the IA32 family,
1328 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1329 AMD support is for families 0x10 and later. You will obviously need
1330 the actual microcode binary data itself which is not shipped with
1331 the Linux kernel.
1332
1333 The preferred method to load microcode from a detached initrd is described
cb1aaebe 1334 in Documentation/x86/microcode.rst. For that you need to enable
5f9c01aa
BP
1335 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1336 initrd for microcode blobs.
1337
c508c46e
BG
1338 In addition, you can build the microcode into the kernel. For that you
1339 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1340 config option.
506f1d07 1341
8d86f390 1342config MICROCODE_INTEL
e43f6e67 1343 bool "Intel microcode loading support"
9c55d99e 1344 depends on CPU_SUP_INTEL && MICROCODE
8f9ca475 1345 default MICROCODE
a7f7f624 1346 help
8f9ca475
IM
1347 This options enables microcode patch loading support for Intel
1348 processors.
1349
b8989db9
A
1350 For the current Intel microcode data package go to
1351 <https://downloadcenter.intel.com> and search for
1352 'Linux Processor Microcode Data File'.
8d86f390 1353
80cc9f10 1354config MICROCODE_AMD
e43f6e67 1355 bool "AMD microcode loading support"
9c55d99e 1356 depends on CPU_SUP_AMD && MICROCODE
a7f7f624 1357 help
8f9ca475
IM
1358 If you select this option, microcode patch loading support for AMD
1359 processors will be enabled.
80cc9f10 1360
a77a94f8
BP
1361config MICROCODE_LATE_LOADING
1362 bool "Late microcode loading (DANGEROUS)"
c02f48e0 1363 default n
506f1d07 1364 depends on MICROCODE
a7f7f624 1365 help
a77a94f8
BP
1366 Loading microcode late, when the system is up and executing instructions
1367 is a tricky business and should be avoided if possible. Just the sequence
1368 of synchronizing all cores and SMT threads is one fragile dance which does
1369 not guarantee that cores might not softlock after the loading. Therefore,
1370 use this at your own risk. Late loading taints the kernel too.
506f1d07
SR
1371
1372config X86_MSR
1373 tristate "/dev/cpu/*/msr - Model-specific register support"
a7f7f624 1374 help
506f1d07
SR
1375 This device gives privileged processes access to the x86
1376 Model-Specific Registers (MSRs). It is a character device with
1377 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1378 MSR accesses are directed to a specific CPU on multi-processor
1379 systems.
1380
1381config X86_CPUID
1382 tristate "/dev/cpu/*/cpuid - CPU information support"
a7f7f624 1383 help
506f1d07
SR
1384 This device gives processes access to the x86 CPUID instruction to
1385 be executed on a specific processor. It is a character device
1386 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1387 /dev/cpu/31/cpuid.
1388
1389choice
1390 prompt "High Memory Support"
6fc108a0 1391 default HIGHMEM4G
506f1d07
SR
1392 depends on X86_32
1393
1394config NOHIGHMEM
1395 bool "off"
a7f7f624 1396 help
506f1d07
SR
1397 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1398 However, the address space of 32-bit x86 processors is only 4
1399 Gigabytes large. That means that, if you have a large amount of
1400 physical memory, not all of it can be "permanently mapped" by the
1401 kernel. The physical memory that's not permanently mapped is called
1402 "high memory".
1403
1404 If you are compiling a kernel which will never run on a machine with
1405 more than 1 Gigabyte total physical RAM, answer "off" here (default
1406 choice and suitable for most users). This will result in a "3GB/1GB"
1407 split: 3GB are mapped so that each process sees a 3GB virtual memory
1408 space and the remaining part of the 4GB virtual memory space is used
1409 by the kernel to permanently map as much physical memory as
1410 possible.
1411
1412 If the machine has between 1 and 4 Gigabytes physical RAM, then
1413 answer "4GB" here.
1414
1415 If more than 4 Gigabytes is used then answer "64GB" here. This
1416 selection turns Intel PAE (Physical Address Extension) mode on.
1417 PAE implements 3-level paging on IA32 processors. PAE is fully
1418 supported by Linux, PAE mode is implemented on all recent Intel
1419 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1420 then the kernel will not boot on CPUs that don't support PAE!
1421
1422 The actual amount of total physical memory will either be
1423 auto detected or can be forced by using a kernel command line option
1424 such as "mem=256M". (Try "man bootparam" or see the documentation of
1425 your boot loader (lilo or loadlin) about how to pass options to the
1426 kernel at boot time.)
1427
1428 If unsure, say "off".
1429
1430config HIGHMEM4G
1431 bool "4GB"
a7f7f624 1432 help
506f1d07
SR
1433 Select this if you have a 32-bit processor and between 1 and 4
1434 gigabytes of physical RAM.
1435
1436config HIGHMEM64G
1437 bool "64GB"
225bac2d 1438 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
506f1d07 1439 select X86_PAE
a7f7f624 1440 help
506f1d07
SR
1441 Select this if you have a 32-bit processor and more than 4
1442 gigabytes of physical RAM.
1443
1444endchoice
1445
1446choice
6a108a14 1447 prompt "Memory split" if EXPERT
506f1d07
SR
1448 default VMSPLIT_3G
1449 depends on X86_32
a7f7f624 1450 help
506f1d07
SR
1451 Select the desired split between kernel and user memory.
1452
1453 If the address range available to the kernel is less than the
1454 physical memory installed, the remaining memory will be available
1455 as "high memory". Accessing high memory is a little more costly
1456 than low memory, as it needs to be mapped into the kernel first.
1457 Note that increasing the kernel address space limits the range
1458 available to user programs, making the address space there
1459 tighter. Selecting anything other than the default 3G/1G split
1460 will also likely make your kernel incompatible with binary-only
1461 kernel modules.
1462
1463 If you are not absolutely sure what you are doing, leave this
1464 option alone!
1465
1466 config VMSPLIT_3G
1467 bool "3G/1G user/kernel split"
1468 config VMSPLIT_3G_OPT
1469 depends on !X86_PAE
1470 bool "3G/1G user/kernel split (for full 1G low memory)"
1471 config VMSPLIT_2G
1472 bool "2G/2G user/kernel split"
1473 config VMSPLIT_2G_OPT
1474 depends on !X86_PAE
1475 bool "2G/2G user/kernel split (for full 2G low memory)"
1476 config VMSPLIT_1G
1477 bool "1G/3G user/kernel split"
1478endchoice
1479
1480config PAGE_OFFSET
1481 hex
1482 default 0xB0000000 if VMSPLIT_3G_OPT
1483 default 0x80000000 if VMSPLIT_2G
1484 default 0x78000000 if VMSPLIT_2G_OPT
1485 default 0x40000000 if VMSPLIT_1G
1486 default 0xC0000000
1487 depends on X86_32
1488
1489config HIGHMEM
3c2362e6 1490 def_bool y
506f1d07 1491 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
506f1d07
SR
1492
1493config X86_PAE
9ba16087 1494 bool "PAE (Physical Address Extension) Support"
506f1d07 1495 depends on X86_32 && !HIGHMEM4G
d4a451d5 1496 select PHYS_ADDR_T_64BIT
9d99c712 1497 select SWIOTLB
a7f7f624 1498 help
506f1d07
SR
1499 PAE is required for NX support, and furthermore enables
1500 larger swapspace support for non-overcommit purposes. It
1501 has the cost of more pagetable lookup overhead, and also
1502 consumes more pagetable space per process.
1503
77ef56e4
KS
1504config X86_5LEVEL
1505 bool "Enable 5-level page tables support"
18ec1eaf 1506 default y
eedb92ab 1507 select DYNAMIC_MEMORY_LAYOUT
162434e7 1508 select SPARSEMEM_VMEMMAP
77ef56e4 1509 depends on X86_64
a7f7f624 1510 help
77ef56e4
KS
1511 5-level paging enables access to larger address space:
1512 upto 128 PiB of virtual address space and 4 PiB of
1513 physical address space.
1514
1515 It will be supported by future Intel CPUs.
1516
6657fca0
KS
1517 A kernel with the option enabled can be booted on machines that
1518 support 4- or 5-level paging.
77ef56e4 1519
cb1aaebe 1520 See Documentation/x86/x86_64/5level-paging.rst for more
77ef56e4
KS
1521 information.
1522
1523 Say N if unsure.
1524
10971ab2 1525config X86_DIRECT_GBPAGES
e5008abe 1526 def_bool y
2e1da13f 1527 depends on X86_64
a7f7f624 1528 help
10971ab2
IM
1529 Certain kernel features effectively disable kernel
1530 linear 1 GB mappings (even if the CPU otherwise
1531 supports them), so don't confuse the user by printing
1532 that we have them enabled.
9e899816 1533
5c280cf6
TG
1534config X86_CPA_STATISTICS
1535 bool "Enable statistic for Change Page Attribute"
1536 depends on DEBUG_FS
a7f7f624 1537 help
b75baaf3 1538 Expose statistics about the Change Page Attribute mechanism, which
a943245a 1539 helps to determine the effectiveness of preserving large and huge
5c280cf6
TG
1540 page mappings when mapping protections are changed.
1541
20f07a04
KS
1542config X86_MEM_ENCRYPT
1543 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1544 select DYNAMIC_PHYSICAL_MASK
20f07a04
KS
1545 def_bool n
1546
7744ccdb
TL
1547config AMD_MEM_ENCRYPT
1548 bool "AMD Secure Memory Encryption (SME) support"
1549 depends on X86_64 && CPU_SUP_AMD
82fef0ad 1550 select DMA_COHERENT_POOL
ce9084ba 1551 select ARCH_USE_MEMREMAP_PROT
597cfe48 1552 select INSTRUCTION_DECODER
aa5a4611 1553 select ARCH_HAS_CC_PLATFORM
20f07a04 1554 select X86_MEM_ENCRYPT
a7f7f624 1555 help
7744ccdb
TL
1556 Say yes to enable support for the encryption of system memory.
1557 This requires an AMD processor that supports Secure Memory
1558 Encryption (SME).
1559
1560config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1561 bool "Activate AMD Secure Memory Encryption (SME) by default"
7744ccdb 1562 depends on AMD_MEM_ENCRYPT
a7f7f624 1563 help
7744ccdb
TL
1564 Say yes to have system memory encrypted by default if running on
1565 an AMD processor that supports Secure Memory Encryption (SME).
1566
1567 If set to Y, then the encryption of system memory can be
1568 deactivated with the mem_encrypt=off command line option.
1569
1570 If set to N, then the encryption of system memory can be
1571 activated with the mem_encrypt=on command line option.
1572
506f1d07
SR
1573# Common NUMA Features
1574config NUMA
e133f6ea 1575 bool "NUMA Memory Allocation and Scheduler Support"
506f1d07 1576 depends on SMP
b5660ba7
PA
1577 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1578 default y if X86_BIGSMP
7ecd19cf 1579 select USE_PERCPU_NUMA_NODE_ID
a7f7f624 1580 help
e133f6ea 1581 Enable NUMA (Non-Uniform Memory Access) support.
fd51b2d7 1582
506f1d07
SR
1583 The kernel will try to allocate memory used by a CPU on the
1584 local memory controller of the CPU and add some more
1585 NUMA awareness to the kernel.
1586
c280ea5e 1587 For 64-bit this is recommended if the system is Intel Core i7
fd51b2d7
KM
1588 (or later), AMD Opteron, or EM64T NUMA.
1589
b5660ba7 1590 For 32-bit this is only needed if you boot a 32-bit
7cf6c945 1591 kernel on a 64-bit NUMA platform.
fd51b2d7
KM
1592
1593 Otherwise, you should say N.
506f1d07 1594
eec1d4fa 1595config AMD_NUMA
3c2362e6
HH
1596 def_bool y
1597 prompt "Old style AMD Opteron NUMA detection"
5da0ef9a 1598 depends on X86_64 && NUMA && PCI
a7f7f624 1599 help
eec1d4fa
HR
1600 Enable AMD NUMA node topology detection. You should say Y here if
1601 you have a multi processor AMD system. This uses an old method to
1602 read the NUMA configuration directly from the builtin Northbridge
1603 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1604 which also takes priority if both are compiled in.
506f1d07
SR
1605
1606config X86_64_ACPI_NUMA
3c2362e6
HH
1607 def_bool y
1608 prompt "ACPI NUMA detection"
506f1d07
SR
1609 depends on X86_64 && NUMA && ACPI && PCI
1610 select ACPI_NUMA
a7f7f624 1611 help
506f1d07
SR
1612 Enable ACPI SRAT based node topology detection.
1613
1614config NUMA_EMU
1615 bool "NUMA emulation"
1b7e03ef 1616 depends on NUMA
a7f7f624 1617 help
506f1d07
SR
1618 Enable NUMA emulation. A flat machine will be split
1619 into virtual nodes when booted with "numa=fake=N", where N is the
1620 number of nodes. This is only useful for debugging.
1621
1622config NODES_SHIFT
d25e26b6 1623 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
51591e31
DR
1624 range 1 10
1625 default "10" if MAXSMP
506f1d07 1626 default "6" if X86_64
506f1d07 1627 default "3"
a9ee6cf5 1628 depends on NUMA
a7f7f624 1629 help
1184dc2f 1630 Specify the maximum number of NUMA Nodes available on the target
692105b8 1631 system. Increases memory reserved to accommodate various tables.
506f1d07 1632
506f1d07
SR
1633config ARCH_FLATMEM_ENABLE
1634 def_bool y
3b16651f 1635 depends on X86_32 && !NUMA
506f1d07 1636
506f1d07
SR
1637config ARCH_SPARSEMEM_ENABLE
1638 def_bool y
6ea30386 1639 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
506f1d07
SR
1640 select SPARSEMEM_STATIC if X86_32
1641 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1642
3b16651f 1643config ARCH_SPARSEMEM_DEFAULT
6ad57f7f 1644 def_bool X86_64 || (NUMA && X86_32)
3b16651f 1645
506f1d07
SR
1646config ARCH_SELECT_MEMORY_MODEL
1647 def_bool y
4eda2bc3 1648 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
506f1d07
SR
1649
1650config ARCH_MEMORY_PROBE
a0842b70 1651 bool "Enable sysfs memory/probe interface"
5c11f00b 1652 depends on MEMORY_HOTPLUG
a0842b70
TK
1653 help
1654 This option enables a sysfs memory/probe interface for testing.
cb1aaebe 1655 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
a0842b70 1656 If you are unsure how to answer this question, answer N.
506f1d07 1657
3b16651f
TH
1658config ARCH_PROC_KCORE_TEXT
1659 def_bool y
1660 depends on X86_64 && PROC_KCORE
1661
a29815a3 1662config ILLEGAL_POINTER_VALUE
b03b016f
KK
1663 hex
1664 default 0 if X86_32
1665 default 0xdead000000000000 if X86_64
a29815a3 1666
7a67832c
DW
1667config X86_PMEM_LEGACY_DEVICE
1668 bool
1669
ec776ef6 1670config X86_PMEM_LEGACY
7a67832c 1671 tristate "Support non-standard NVDIMMs and ADR protected memory"
9f53f9fa
DW
1672 depends on PHYS_ADDR_T_64BIT
1673 depends on BLK_DEV
7a67832c 1674 select X86_PMEM_LEGACY_DEVICE
7b27a862 1675 select NUMA_KEEP_MEMINFO if NUMA
9f53f9fa 1676 select LIBNVDIMM
ec776ef6
CH
1677 help
1678 Treat memory marked using the non-standard e820 type of 12 as used
1679 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1680 The kernel will offer these regions to the 'pmem' driver so
1681 they can be used for persistent storage.
1682
1683 Say Y if unsure.
1684
506f1d07
SR
1685config HIGHPTE
1686 bool "Allocate 3rd-level pagetables from highmem"
6fc108a0 1687 depends on HIGHMEM
a7f7f624 1688 help
506f1d07
SR
1689 The VM uses one page table entry for each page of physical memory.
1690 For systems with a lot of RAM, this can be wasteful of precious
1691 low memory. Setting this option will put user-space page table
1692 entries in high memory.
1693
9f077871 1694config X86_CHECK_BIOS_CORRUPTION
8f9ca475 1695 bool "Check for low memory corruption"
a7f7f624 1696 help
8f9ca475
IM
1697 Periodically check for memory corruption in low memory, which
1698 is suspected to be caused by BIOS. Even when enabled in the
1699 configuration, it is disabled at runtime. Enable it by
1700 setting "memory_corruption_check=1" on the kernel command
1701 line. By default it scans the low 64k of memory every 60
1702 seconds; see the memory_corruption_check_size and
1703 memory_corruption_check_period parameters in
8c27ceff 1704 Documentation/admin-guide/kernel-parameters.rst to adjust this.
8f9ca475
IM
1705
1706 When enabled with the default parameters, this option has
1707 almost no overhead, as it reserves a relatively small amount
1708 of memory and scans it infrequently. It both detects corruption
1709 and prevents it from affecting the running system.
1710
1711 It is, however, intended as a diagnostic tool; if repeatable
1712 BIOS-originated corruption always affects the same memory,
1713 you can use memmap= to prevent the kernel from using that
1714 memory.
9f077871 1715
c885df50 1716config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
8f9ca475 1717 bool "Set the default setting of memory_corruption_check"
c885df50
JF
1718 depends on X86_CHECK_BIOS_CORRUPTION
1719 default y
a7f7f624 1720 help
8f9ca475
IM
1721 Set whether the default state of memory_corruption_check is
1722 on or off.
c885df50 1723
506f1d07
SR
1724config MATH_EMULATION
1725 bool
a5b9e5a2 1726 depends on MODIFY_LDT_SYSCALL
87d6021b 1727 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
a7f7f624 1728 help
506f1d07
SR
1729 Linux can emulate a math coprocessor (used for floating point
1730 operations) if you don't have one. 486DX and Pentium processors have
1731 a math coprocessor built in, 486SX and 386 do not, unless you added
1732 a 487DX or 387, respectively. (The messages during boot time can
1733 give you some hints here ["man dmesg"].) Everyone needs either a
1734 coprocessor or this emulation.
1735
1736 If you don't have a math coprocessor, you need to say Y here; if you
1737 say Y here even though you have a coprocessor, the coprocessor will
1738 be used nevertheless. (This behavior can be changed with the kernel
1739 command line option "no387", which comes handy if your coprocessor
1740 is broken. Try "man bootparam" or see the documentation of your boot
1741 loader (lilo or loadlin) about how to pass options to the kernel at
1742 boot time.) This means that it is a good idea to say Y here if you
1743 intend to use this kernel on different machines.
1744
1745 More information about the internals of the Linux math coprocessor
1746 emulation can be found in <file:arch/x86/math-emu/README>.
1747
1748 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1749 kernel, it won't hurt.
1750
1751config MTRR
6fc108a0 1752 def_bool y
6a108a14 1753 prompt "MTRR (Memory Type Range Register) support" if EXPERT
a7f7f624 1754 help
506f1d07
SR
1755 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1756 the Memory Type Range Registers (MTRRs) may be used to control
1757 processor access to memory ranges. This is most useful if you have
1758 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1759 allows bus write transfers to be combined into a larger transfer
1760 before bursting over the PCI/AGP bus. This can increase performance
1761 of image write operations 2.5 times or more. Saying Y here creates a
1762 /proc/mtrr file which may be used to manipulate your processor's
1763 MTRRs. Typically the X server should use this.
1764
1765 This code has a reasonably generic interface so that similar
1766 control registers on other processors can be easily supported
1767 as well:
1768
1769 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1770 Registers (ARRs) which provide a similar functionality to MTRRs. For
1771 these, the ARRs are used to emulate the MTRRs.
1772 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1773 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1774 write-combining. All of these processors are supported by this code
1775 and it makes sense to say Y here if you have one of them.
1776
1777 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1778 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1779 can lead to all sorts of problems, so it's good to say Y here.
1780
1781 You can safely say Y even if your machine doesn't have MTRRs, you'll
1782 just add about 9 KB to your kernel.
1783
cb1aaebe 1784 See <file:Documentation/x86/mtrr.rst> for more information.
506f1d07 1785
95ffa243 1786config MTRR_SANITIZER
2ffb3501 1787 def_bool y
95ffa243
YL
1788 prompt "MTRR cleanup support"
1789 depends on MTRR
a7f7f624 1790 help
aba3728c
TG
1791 Convert MTRR layout from continuous to discrete, so X drivers can
1792 add writeback entries.
95ffa243 1793
aba3728c 1794 Can be disabled with disable_mtrr_cleanup on the kernel command line.
692105b8 1795 The largest mtrr entry size for a continuous block can be set with
aba3728c 1796 mtrr_chunk_size.
95ffa243 1797
2ffb3501 1798 If unsure, say Y.
95ffa243
YL
1799
1800config MTRR_SANITIZER_ENABLE_DEFAULT
f5098d62
YL
1801 int "MTRR cleanup enable value (0-1)"
1802 range 0 1
1803 default "0"
95ffa243 1804 depends on MTRR_SANITIZER
a7f7f624 1805 help
f5098d62 1806 Enable mtrr cleanup default value
95ffa243 1807
12031a62
YL
1808config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1809 int "MTRR cleanup spare reg num (0-7)"
1810 range 0 7
1811 default "1"
1812 depends on MTRR_SANITIZER
a7f7f624 1813 help
12031a62 1814 mtrr cleanup spare entries default, it can be changed via
aba3728c 1815 mtrr_spare_reg_nr=N on the kernel command line.
12031a62 1816
2e5d9c85 1817config X86_PAT
6fc108a0 1818 def_bool y
6a108a14 1819 prompt "x86 PAT support" if EXPERT
2a8a2719 1820 depends on MTRR
a7f7f624 1821 help
2e5d9c85 1822 Use PAT attributes to setup page level cache control.
042b78e4 1823
2e5d9c85 1824 PATs are the modern equivalents of MTRRs and are much more
1825 flexible than MTRRs.
1826
1827 Say N here if you see bootup problems (boot crash, boot hang,
042b78e4 1828 spontaneous reboots) or a non-working video driver.
2e5d9c85 1829
1830 If unsure, say Y.
1831
46cf98cd
VP
1832config ARCH_USES_PG_UNCACHED
1833 def_bool y
1834 depends on X86_PAT
1835
628c6246
PA
1836config ARCH_RANDOM
1837 def_bool y
1838 prompt "x86 architectural random number generator" if EXPERT
a7f7f624 1839 help
628c6246
PA
1840 Enable the x86 architectural RDRAND instruction
1841 (Intel Bull Mountain technology) to generate random numbers.
1842 If supported, this is a high bandwidth, cryptographically
1843 secure hardware random number generator.
1844
b971880f 1845config X86_UMIP
796ebc81 1846 def_bool y
b971880f 1847 prompt "User Mode Instruction Prevention" if EXPERT
a7f7f624 1848 help
b971880f
BM
1849 User Mode Instruction Prevention (UMIP) is a security feature in
1850 some x86 processors. If enabled, a general protection fault is
1851 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1852 executed in user mode. These instructions unnecessarily expose
1853 information about the hardware state.
796ebc81
RN
1854
1855 The vast majority of applications do not use these instructions.
1856 For the very few that do, software emulation is provided in
1857 specific cases in protected and virtual-8086 modes. Emulated
1858 results are dummy.
aa35f896 1859
156ff4a5
PZ
1860config CC_HAS_IBT
1861 # GCC >= 9 and binutils >= 2.29
1862 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1863 # Clang/LLVM >= 14
262448f3
NC
1864 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1865 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
156ff4a5 1866 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
262448f3 1867 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
156ff4a5
PZ
1868 $(as-instr,endbr64)
1869
1870config X86_KERNEL_IBT
1871 prompt "Indirect Branch Tracking"
1872 bool
03f16cd0 1873 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
f6a2c2b2
NC
1874 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1875 depends on !LD_IS_LLD || LLD_VERSION >= 140000
03f16cd0 1876 select OBJTOOL
156ff4a5
PZ
1877 help
1878 Build the kernel with support for Indirect Branch Tracking, a
1879 hardware support course-grain forward-edge Control Flow Integrity
1880 protection. It enforces that all indirect calls must land on
1881 an ENDBR instruction, as such, the compiler will instrument the
1882 code with them to make this happen.
1883
ed53a0d9 1884 In addition to building the kernel with IBT, seal all functions that
4cdfc11b 1885 are not indirect call targets, avoiding them ever becoming one.
ed53a0d9
PZ
1886
1887 This requires LTO like objtool runs and will slow down the build. It
1888 does significantly reduce the number of ENDBR instructions in the
1889 kernel image.
1890
35e97790 1891config X86_INTEL_MEMORY_PROTECTION_KEYS
38f3e775 1892 prompt "Memory Protection Keys"
35e97790 1893 def_bool y
284244a9 1894 # Note: only available in 64-bit mode
38f3e775 1895 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
52c8e601
IM
1896 select ARCH_USES_HIGH_VMA_FLAGS
1897 select ARCH_HAS_PKEYS
a7f7f624 1898 help
284244a9
DH
1899 Memory Protection Keys provides a mechanism for enforcing
1900 page-based protections, but without requiring modification of the
1901 page tables when an application changes protection domains.
1902
1eecbcdc 1903 For details, see Documentation/core-api/protection-keys.rst
284244a9
DH
1904
1905 If unsure, say y.
35e97790 1906
db616173
MH
1907choice
1908 prompt "TSX enable mode"
1909 depends on CPU_SUP_INTEL
1910 default X86_INTEL_TSX_MODE_OFF
1911 help
1912 Intel's TSX (Transactional Synchronization Extensions) feature
1913 allows to optimize locking protocols through lock elision which
1914 can lead to a noticeable performance boost.
1915
1916 On the other hand it has been shown that TSX can be exploited
1917 to form side channel attacks (e.g. TAA) and chances are there
1918 will be more of those attacks discovered in the future.
1919
1920 Therefore TSX is not enabled by default (aka tsx=off). An admin
1921 might override this decision by tsx=on the command line parameter.
1922 Even with TSX enabled, the kernel will attempt to enable the best
1923 possible TAA mitigation setting depending on the microcode available
1924 for the particular machine.
1925
1926 This option allows to set the default tsx mode between tsx=on, =off
1927 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1928 details.
1929
1930 Say off if not sure, auto if TSX is in use but it should be used on safe
1931 platforms or on if TSX is in use and the security aspect of tsx is not
1932 relevant.
1933
1934config X86_INTEL_TSX_MODE_OFF
1935 bool "off"
1936 help
1937 TSX is disabled if possible - equals to tsx=off command line parameter.
1938
1939config X86_INTEL_TSX_MODE_ON
1940 bool "on"
1941 help
1942 TSX is always enabled on TSX capable HW - equals the tsx=on command
1943 line parameter.
1944
1945config X86_INTEL_TSX_MODE_AUTO
1946 bool "auto"
1947 help
1948 TSX is enabled on TSX capable HW that is believed to be safe against
1949 side channel attacks- equals the tsx=auto command line parameter.
1950endchoice
1951
e7e05452
SC
1952config X86_SGX
1953 bool "Software Guard eXtensions (SGX)"
1954 depends on X86_64 && CPU_SUP_INTEL
1955 depends on CRYPTO=y
1956 depends on CRYPTO_SHA256=y
1957 select SRCU
1958 select MMU_NOTIFIER
901ddbb9 1959 select NUMA_KEEP_MEMINFO if NUMA
40e0e784 1960 select XARRAY_MULTI
e7e05452
SC
1961 help
1962 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1963 that can be used by applications to set aside private regions of code
1964 and data, referred to as enclaves. An enclave's private memory can
1965 only be accessed by code running within the enclave. Accesses from
1966 outside the enclave, including other enclaves, are disallowed by
1967 hardware.
1968
1969 If unsure, say N.
1970
506f1d07 1971config EFI
9ba16087 1972 bool "EFI runtime service support"
5b83683f 1973 depends on ACPI
f6ce5002 1974 select UCS2_STRING
022ee6c5 1975 select EFI_RUNTIME_WRAPPERS
1ff2fc02 1976 select ARCH_USE_MEMREMAP_PROT
a7f7f624 1977 help
8f9ca475
IM
1978 This enables the kernel to use EFI runtime services that are
1979 available (such as the EFI variable services).
506f1d07 1980
8f9ca475
IM
1981 This option is only useful on systems that have EFI firmware.
1982 In addition, you should use the latest ELILO loader available
1983 at <http://elilo.sourceforge.net> in order to take advantage
1984 of EFI runtime services. However, even with this option, the
1985 resultant kernel should continue to boot on existing non-EFI
1986 platforms.
506f1d07 1987
291f3632 1988config EFI_STUB
8f24f8c2 1989 bool "EFI stub support"
c6dbd3e5 1990 depends on EFI
8f24f8c2
AB
1991 depends on $(cc-option,-mabi=ms) || X86_32
1992 select RELOCATABLE
a7f7f624 1993 help
8f24f8c2 1994 This kernel feature allows a bzImage to be loaded directly
291f3632
MF
1995 by EFI firmware without the use of a bootloader.
1996
4f4cfa6c 1997 See Documentation/admin-guide/efi-stub.rst for more information.
0c759662 1998
7d453eee
MF
1999config EFI_MIXED
2000 bool "EFI mixed-mode support"
2001 depends on EFI_STUB && X86_64
a7f7f624 2002 help
758cd94a
JH
2003 Enabling this feature allows a 64-bit kernel to be booted
2004 on a 32-bit firmware, provided that your CPU supports 64-bit
2005 mode.
7d453eee 2006
758cd94a
JH
2007 Note that it is not possible to boot a mixed-mode enabled
2008 kernel via the EFI boot stub - a bootloader that supports
2009 the EFI handover protocol must be used.
7d453eee 2010
758cd94a 2011 If unsure, say N.
7d453eee 2012
8636a1f9 2013source "kernel/Kconfig.hz"
506f1d07
SR
2014
2015config KEXEC
2016 bool "kexec system call"
2965faa5 2017 select KEXEC_CORE
a7f7f624 2018 help
506f1d07
SR
2019 kexec is a system call that implements the ability to shutdown your
2020 current kernel, and to start another kernel. It is like a reboot
2021 but it is independent of the system firmware. And like a reboot
2022 you can start any kernel with it, not just Linux.
2023
2024 The name comes from the similarity to the exec system call.
2025
2026 It is an ongoing process to be certain the hardware in a machine
2027 is properly shutdown, so do not be surprised if this code does not
bf220695
GU
2028 initially work for you. As of this writing the exact hardware
2029 interface is strongly in flux, so no good recommendation can be
2030 made.
506f1d07 2031
74ca317c
VG
2032config KEXEC_FILE
2033 bool "kexec file based system call"
2965faa5 2034 select KEXEC_CORE
74ca317c 2035 select BUILD_BIN2C
74ca317c
VG
2036 depends on X86_64
2037 depends on CRYPTO=y
2038 depends on CRYPTO_SHA256=y
a7f7f624 2039 help
74ca317c
VG
2040 This is new version of kexec system call. This system call is
2041 file based and takes file descriptors as system call argument
2042 for kernel and initramfs as opposed to list of segments as
2043 accepted by previous system call.
2044
b799a09f
AT
2045config ARCH_HAS_KEXEC_PURGATORY
2046 def_bool KEXEC_FILE
2047
99d5cadf 2048config KEXEC_SIG
8e7d8381 2049 bool "Verify kernel signature during kexec_file_load() syscall"
74ca317c 2050 depends on KEXEC_FILE
a7f7f624 2051 help
d8eb8940 2052
99d5cadf
JB
2053 This option makes the kexec_file_load() syscall check for a valid
2054 signature of the kernel image. The image can still be loaded without
2055 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2056 there's a signature that we can check, then it must be valid.
2057
2058 In addition to this option, you need to enable signature
d8eb8940
BP
2059 verification for the corresponding kernel image type being
2060 loaded in order for this to work.
8e7d8381 2061
99d5cadf
JB
2062config KEXEC_SIG_FORCE
2063 bool "Require a valid signature in kexec_file_load() syscall"
2064 depends on KEXEC_SIG
a7f7f624 2065 help
99d5cadf
JB
2066 This option makes kernel signature verification mandatory for
2067 the kexec_file_load() syscall.
2068
8e7d8381
VG
2069config KEXEC_BZIMAGE_VERIFY_SIG
2070 bool "Enable bzImage signature verification support"
99d5cadf 2071 depends on KEXEC_SIG
8e7d8381
VG
2072 depends on SIGNED_PE_FILE_VERIFICATION
2073 select SYSTEM_TRUSTED_KEYRING
a7f7f624 2074 help
8e7d8381
VG
2075 Enable bzImage signature verification support.
2076
506f1d07 2077config CRASH_DUMP
04b69447 2078 bool "kernel crash dumps"
506f1d07 2079 depends on X86_64 || (X86_32 && HIGHMEM)
a7f7f624 2080 help
506f1d07
SR
2081 Generate crash dump after being started by kexec.
2082 This should be normally only set in special crash dump kernels
2083 which are loaded in the main kernel with kexec-tools into
2084 a specially reserved region and then later executed after
2085 a crash by kdump/kexec. The crash dump kernel must be compiled
2086 to a memory address not used by the main kernel or BIOS using
2087 PHYSICAL_START, or it must be built as a relocatable image
2088 (CONFIG_RELOCATABLE=y).
330d4810 2089 For more details see Documentation/admin-guide/kdump/kdump.rst
506f1d07 2090
3ab83521 2091config KEXEC_JUMP
6ea30386 2092 bool "kexec jump"
fee7b0d8 2093 depends on KEXEC && HIBERNATION
a7f7f624 2094 help
89081d17
HY
2095 Jump between original kernel and kexeced kernel and invoke
2096 code in physical address mode via KEXEC
3ab83521 2097
506f1d07 2098config PHYSICAL_START
6a108a14 2099 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
ceefccc9 2100 default "0x1000000"
a7f7f624 2101 help
506f1d07
SR
2102 This gives the physical address where the kernel is loaded.
2103
2104 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2105 bzImage will decompress itself to above physical address and
2106 run from there. Otherwise, bzImage will run from the address where
2107 it has been loaded by the boot loader and will ignore above physical
2108 address.
2109
2110 In normal kdump cases one does not have to set/change this option
2111 as now bzImage can be compiled as a completely relocatable image
2112 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2113 address. This option is mainly useful for the folks who don't want
2114 to use a bzImage for capturing the crash dump and want to use a
2115 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2116 to be specifically compiled to run from a specific memory area
2117 (normally a reserved region) and this option comes handy.
2118
ceefccc9
PA
2119 So if you are using bzImage for capturing the crash dump,
2120 leave the value here unchanged to 0x1000000 and set
2121 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2122 for capturing the crash dump change this value to start of
2123 the reserved region. In other words, it can be set based on
2124 the "X" value as specified in the "crashkernel=YM@XM"
2125 command line boot parameter passed to the panic-ed
330d4810 2126 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
ceefccc9 2127 for more details about crash dumps.
506f1d07
SR
2128
2129 Usage of bzImage for capturing the crash dump is recommended as
2130 one does not have to build two kernels. Same kernel can be used
2131 as production kernel and capture kernel. Above option should have
2132 gone away after relocatable bzImage support is introduced. But it
2133 is present because there are users out there who continue to use
2134 vmlinux for dump capture. This option should go away down the
2135 line.
2136
2137 Don't change this unless you know what you are doing.
2138
2139config RELOCATABLE
26717808
PA
2140 bool "Build a relocatable kernel"
2141 default y
a7f7f624 2142 help
506f1d07
SR
2143 This builds a kernel image that retains relocation information
2144 so it can be loaded someplace besides the default 1MB.
2145 The relocations tend to make the kernel binary about 10% larger,
2146 but are discarded at runtime.
2147
2148 One use is for the kexec on panic case where the recovery kernel
2149 must live at a different physical address than the primary
2150 kernel.
2151
2152 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2153 it has been loaded at and the compile time physical address
8ab3820f 2154 (CONFIG_PHYSICAL_START) is used as the minimum location.
506f1d07 2155
8ab3820f 2156config RANDOMIZE_BASE
e8581e3d 2157 bool "Randomize the address of the kernel image (KASLR)"
8ab3820f 2158 depends on RELOCATABLE
6807c846 2159 default y
a7f7f624 2160 help
e8581e3d
BH
2161 In support of Kernel Address Space Layout Randomization (KASLR),
2162 this randomizes the physical address at which the kernel image
2163 is decompressed and the virtual address where the kernel
2164 image is mapped, as a security feature that deters exploit
2165 attempts relying on knowledge of the location of kernel
2166 code internals.
2167
ed9f007e
KC
2168 On 64-bit, the kernel physical and virtual addresses are
2169 randomized separately. The physical address will be anywhere
2170 between 16MB and the top of physical memory (up to 64TB). The
2171 virtual address will be randomized from 16MB up to 1GB (9 bits
2172 of entropy). Note that this also reduces the memory space
2173 available to kernel modules from 1.5GB to 1GB.
2174
2175 On 32-bit, the kernel physical and virtual addresses are
2176 randomized together. They will be randomized from 16MB up to
2177 512MB (8 bits of entropy).
e8581e3d
BH
2178
2179 Entropy is generated using the RDRAND instruction if it is
2180 supported. If RDTSC is supported, its value is mixed into
2181 the entropy pool as well. If neither RDRAND nor RDTSC are
ed9f007e
KC
2182 supported, then entropy is read from the i8254 timer. The
2183 usable entropy is limited by the kernel being built using
2184 2GB addressing, and that PHYSICAL_ALIGN must be at a
2185 minimum of 2MB. As a result, only 10 bits of entropy are
2186 theoretically possible, but the implementations are further
2187 limited due to memory layouts.
e8581e3d 2188
6807c846 2189 If unsure, say Y.
8ab3820f
KC
2190
2191# Relocation on x86 needs some additional build support
845adf72
PA
2192config X86_NEED_RELOCS
2193 def_bool y
8ab3820f 2194 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
845adf72 2195
506f1d07 2196config PHYSICAL_ALIGN
a0215061 2197 hex "Alignment value to which kernel should be aligned"
8ab3820f 2198 default "0x200000"
a0215061
KC
2199 range 0x2000 0x1000000 if X86_32
2200 range 0x200000 0x1000000 if X86_64
a7f7f624 2201 help
506f1d07
SR
2202 This value puts the alignment restrictions on physical address
2203 where kernel is loaded and run from. Kernel is compiled for an
2204 address which meets above alignment restriction.
2205
2206 If bootloader loads the kernel at a non-aligned address and
2207 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2208 address aligned to above value and run from there.
2209
2210 If bootloader loads the kernel at a non-aligned address and
2211 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2212 load address and decompress itself to the address it has been
2213 compiled for and run from there. The address for which kernel is
2214 compiled already meets above alignment restrictions. Hence the
2215 end result is that kernel runs from a physical address meeting
2216 above alignment restrictions.
2217
a0215061
KC
2218 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2219 this value must be a multiple of 0x200000.
2220
506f1d07
SR
2221 Don't change this unless you know what you are doing.
2222
eedb92ab
KS
2223config DYNAMIC_MEMORY_LAYOUT
2224 bool
a7f7f624 2225 help
eedb92ab
KS
2226 This option makes base addresses of vmalloc and vmemmap as well as
2227 __PAGE_OFFSET movable during boot.
2228
0483e1fa
TG
2229config RANDOMIZE_MEMORY
2230 bool "Randomize the kernel memory sections"
2231 depends on X86_64
2232 depends on RANDOMIZE_BASE
eedb92ab 2233 select DYNAMIC_MEMORY_LAYOUT
0483e1fa 2234 default RANDOMIZE_BASE
a7f7f624 2235 help
758cd94a
JH
2236 Randomizes the base virtual address of kernel memory sections
2237 (physical memory mapping, vmalloc & vmemmap). This security feature
2238 makes exploits relying on predictable memory locations less reliable.
0483e1fa 2239
758cd94a
JH
2240 The order of allocations remains unchanged. Entropy is generated in
2241 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2242 configuration have in average 30,000 different possible virtual
2243 addresses for each memory section.
0483e1fa 2244
758cd94a 2245 If unsure, say Y.
0483e1fa 2246
90397a41
TG
2247config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2248 hex "Physical memory mapping padding" if EXPERT
2249 depends on RANDOMIZE_MEMORY
2250 default "0xa" if MEMORY_HOTPLUG
2251 default "0x0"
2252 range 0x1 0x40 if MEMORY_HOTPLUG
2253 range 0x0 0x40
a7f7f624 2254 help
758cd94a
JH
2255 Define the padding in terabytes added to the existing physical
2256 memory size during kernel memory randomization. It is useful
2257 for memory hotplug support but reduces the entropy available for
2258 address randomization.
90397a41 2259
758cd94a 2260 If unsure, leave at the default value.
90397a41 2261
506f1d07 2262config HOTPLUG_CPU
bebd024e 2263 def_bool y
40b31360 2264 depends on SMP
506f1d07 2265
80aa1dff
FY
2266config BOOTPARAM_HOTPLUG_CPU0
2267 bool "Set default setting of cpu0_hotpluggable"
2c922cd0 2268 depends on HOTPLUG_CPU
a7f7f624 2269 help
80aa1dff
FY
2270 Set whether default state of cpu0_hotpluggable is on or off.
2271
2272 Say Y here to enable CPU0 hotplug by default. If this switch
2273 is turned on, there is no need to give cpu0_hotplug kernel
2274 parameter and the CPU0 hotplug feature is enabled by default.
2275
2276 Please note: there are two known CPU0 dependencies if you want
2277 to enable the CPU0 hotplug feature either by this switch or by
2278 cpu0_hotplug kernel parameter.
2279
2280 First, resume from hibernate or suspend always starts from CPU0.
2281 So hibernate and suspend are prevented if CPU0 is offline.
2282
2283 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2284 offline if any interrupt can not migrate out of CPU0. There may
2285 be other CPU0 dependencies.
2286
2287 Please make sure the dependencies are under your control before
2288 you enable this feature.
2289
2290 Say N if you don't want to enable CPU0 hotplug feature by default.
2291 You still can enable the CPU0 hotplug feature at boot by kernel
2292 parameter cpu0_hotplug.
2293
a71c8bc5
FY
2294config DEBUG_HOTPLUG_CPU0
2295 def_bool n
2296 prompt "Debug CPU0 hotplug"
2c922cd0 2297 depends on HOTPLUG_CPU
a7f7f624 2298 help
a71c8bc5
FY
2299 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2300 soon as possible and boots up userspace with CPU0 offlined. User
2301 can online CPU0 back after boot time.
2302
2303 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2304 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2305 compilation or giving cpu0_hotplug kernel parameter at boot.
2306
2307 If unsure, say N.
2308
506f1d07 2309config COMPAT_VDSO
b0b49f26
AL
2310 def_bool n
2311 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
953fee1d 2312 depends on COMPAT_32
a7f7f624 2313 help
b0b49f26
AL
2314 Certain buggy versions of glibc will crash if they are
2315 presented with a 32-bit vDSO that is not mapped at the address
2316 indicated in its segment table.
e84446de 2317
b0b49f26
AL
2318 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2319 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2320 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2321 the only released version with the bug, but OpenSUSE 9
2322 contains a buggy "glibc 2.3.2".
506f1d07 2323
b0b49f26
AL
2324 The symptom of the bug is that everything crashes on startup, saying:
2325 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2326
2327 Saying Y here changes the default value of the vdso32 boot
2328 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2329 This works around the glibc bug but hurts performance.
2330
2331 If unsure, say N: if you are compiling your own kernel, you
2332 are unlikely to be using a buggy version of glibc.
506f1d07 2333
3dc33bd3
KC
2334choice
2335 prompt "vsyscall table for legacy applications"
2336 depends on X86_64
625b7b7f 2337 default LEGACY_VSYSCALL_XONLY
3dc33bd3
KC
2338 help
2339 Legacy user code that does not know how to find the vDSO expects
2340 to be able to issue three syscalls by calling fixed addresses in
2341 kernel space. Since this location is not randomized with ASLR,
2342 it can be used to assist security vulnerability exploitation.
2343
2344 This setting can be changed at boot time via the kernel command
bf00745e
AL
2345 line parameter vsyscall=[emulate|xonly|none]. Emulate mode
2346 is deprecated and can only be enabled using the kernel command
2347 line.
3dc33bd3
KC
2348
2349 On a system with recent enough glibc (2.14 or newer) and no
2350 static binaries, you can say None without a performance penalty
2351 to improve security.
2352
bd49e16e 2353 If unsure, select "Emulate execution only".
3dc33bd3 2354
bd49e16e
AL
2355 config LEGACY_VSYSCALL_XONLY
2356 bool "Emulate execution only"
2357 help
2358 The kernel traps and emulates calls into the fixed vsyscall
2359 address mapping and does not allow reads. This
2360 configuration is recommended when userspace might use the
2361 legacy vsyscall area but support for legacy binary
2362 instrumentation of legacy code is not needed. It mitigates
2363 certain uses of the vsyscall area as an ASLR-bypassing
2364 buffer.
3dc33bd3
KC
2365
2366 config LEGACY_VSYSCALL_NONE
2367 bool "None"
2368 help
2369 There will be no vsyscall mapping at all. This will
2370 eliminate any risk of ASLR bypass due to the vsyscall
2371 fixed address mapping. Attempts to use the vsyscalls
2372 will be reported to dmesg, so that either old or
2373 malicious userspace programs can be identified.
2374
2375endchoice
2376
516cbf37
TB
2377config CMDLINE_BOOL
2378 bool "Built-in kernel command line"
a7f7f624 2379 help
516cbf37
TB
2380 Allow for specifying boot arguments to the kernel at
2381 build time. On some systems (e.g. embedded ones), it is
2382 necessary or convenient to provide some or all of the
2383 kernel boot arguments with the kernel itself (that is,
2384 to not rely on the boot loader to provide them.)
2385
2386 To compile command line arguments into the kernel,
2387 set this option to 'Y', then fill in the
69711ca1 2388 boot arguments in CONFIG_CMDLINE.
516cbf37
TB
2389
2390 Systems with fully functional boot loaders (i.e. non-embedded)
2391 should leave this option set to 'N'.
2392
2393config CMDLINE
2394 string "Built-in kernel command string"
2395 depends on CMDLINE_BOOL
2396 default ""
a7f7f624 2397 help
516cbf37
TB
2398 Enter arguments here that should be compiled into the kernel
2399 image and used at boot time. If the boot loader provides a
2400 command line at boot time, it is appended to this string to
2401 form the full kernel command line, when the system boots.
2402
2403 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2404 change this behavior.
2405
2406 In most cases, the command line (whether built-in or provided
2407 by the boot loader) should specify the device for the root
2408 file system.
2409
2410config CMDLINE_OVERRIDE
2411 bool "Built-in command line overrides boot loader arguments"
645e6466 2412 depends on CMDLINE_BOOL && CMDLINE != ""
a7f7f624 2413 help
516cbf37
TB
2414 Set this option to 'Y' to have the kernel ignore the boot loader
2415 command line, and use ONLY the built-in command line.
2416
2417 This is used to work around broken boot loaders. This should
2418 be set to 'N' under normal conditions.
2419
a5b9e5a2
AL
2420config MODIFY_LDT_SYSCALL
2421 bool "Enable the LDT (local descriptor table)" if EXPERT
2422 default y
a7f7f624 2423 help
a5b9e5a2
AL
2424 Linux can allow user programs to install a per-process x86
2425 Local Descriptor Table (LDT) using the modify_ldt(2) system
2426 call. This is required to run 16-bit or segmented code such as
2427 DOSEMU or some Wine programs. It is also used by some very old
2428 threading libraries.
2429
2430 Enabling this feature adds a small amount of overhead to
2431 context switches and increases the low-level kernel attack
2432 surface. Disabling it removes the modify_ldt(2) system call.
2433
2434 Saying 'N' here may make sense for embedded or server kernels.
2435
3aac3ebe
TG
2436config STRICT_SIGALTSTACK_SIZE
2437 bool "Enforce strict size checking for sigaltstack"
2438 depends on DYNAMIC_SIGFRAME
2439 help
2440 For historical reasons MINSIGSTKSZ is a constant which became
2441 already too small with AVX512 support. Add a mechanism to
2442 enforce strict checking of the sigaltstack size against the
2443 real size of the FPU frame. This option enables the check
2444 by default. It can also be controlled via the kernel command
2445 line option 'strict_sas_size' independent of this config
2446 switch. Enabling it might break existing applications which
2447 allocate a too small sigaltstack but 'work' because they
2448 never get a signal delivered.
2449
2450 Say 'N' unless you want to really enforce this check.
2451
b700e7f0
SJ
2452source "kernel/livepatch/Kconfig"
2453
506f1d07
SR
2454endmenu
2455
3072e413
MH
2456config ARCH_HAS_ADD_PAGES
2457 def_bool y
5c11f00b 2458 depends on ARCH_ENABLE_MEMORY_HOTPLUG
3072e413 2459
f91ef222
OS
2460config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2461 def_bool y
2462
da85f865 2463menu "Power management and ACPI options"
e279b6c1
SR
2464
2465config ARCH_HIBERNATION_HEADER
3c2362e6 2466 def_bool y
44556530 2467 depends on HIBERNATION
e279b6c1
SR
2468
2469source "kernel/power/Kconfig"
2470
2471source "drivers/acpi/Kconfig"
2472
a6b68076 2473config X86_APM_BOOT
6fc108a0 2474 def_bool y
282e5aab 2475 depends on APM
a6b68076 2476
e279b6c1
SR
2477menuconfig APM
2478 tristate "APM (Advanced Power Management) BIOS support"
efefa6f6 2479 depends on X86_32 && PM_SLEEP
a7f7f624 2480 help
e279b6c1
SR
2481 APM is a BIOS specification for saving power using several different
2482 techniques. This is mostly useful for battery powered laptops with
2483 APM compliant BIOSes. If you say Y here, the system time will be
2484 reset after a RESUME operation, the /proc/apm device will provide
2485 battery status information, and user-space programs will receive
2486 notification of APM "events" (e.g. battery status change).
2487
2488 If you select "Y" here, you can disable actual use of the APM
2489 BIOS by passing the "apm=off" option to the kernel at boot time.
2490
2491 Note that the APM support is almost completely disabled for
2492 machines with more than one CPU.
2493
2494 In order to use APM, you will need supporting software. For location
151f4e2b 2495 and more information, read <file:Documentation/power/apm-acpi.rst>
2dc98fd3 2496 and the Battery Powered Linux mini-HOWTO, available from
e279b6c1
SR
2497 <http://www.tldp.org/docs.html#howto>.
2498
2499 This driver does not spin down disk drives (see the hdparm(8)
2500 manpage ("man 8 hdparm") for that), and it doesn't turn off
2501 VESA-compliant "green" monitors.
2502
2503 This driver does not support the TI 4000M TravelMate and the ACER
2504 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2505 desktop machines also don't have compliant BIOSes, and this driver
2506 may cause those machines to panic during the boot phase.
2507
2508 Generally, if you don't have a battery in your machine, there isn't
2509 much point in using this driver and you should say N. If you get
2510 random kernel OOPSes or reboots that don't seem to be related to
2511 anything, try disabling/enabling this option (or disabling/enabling
2512 APM in your BIOS).
2513
2514 Some other things you should try when experiencing seemingly random,
2515 "weird" problems:
2516
2517 1) make sure that you have enough swap space and that it is
2518 enabled.
2519 2) pass the "no-hlt" option to the kernel
2520 3) switch on floating point emulation in the kernel and pass
2521 the "no387" option to the kernel
2522 4) pass the "floppy=nodma" option to the kernel
2523 5) pass the "mem=4M" option to the kernel (thereby disabling
2524 all but the first 4 MB of RAM)
2525 6) make sure that the CPU is not over clocked.
2526 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2527 8) disable the cache from your BIOS settings
2528 9) install a fan for the video card or exchange video RAM
2529 10) install a better fan for the CPU
2530 11) exchange RAM chips
2531 12) exchange the motherboard.
2532
2533 To compile this driver as a module, choose M here: the
2534 module will be called apm.
2535
2536if APM
2537
2538config APM_IGNORE_USER_SUSPEND
2539 bool "Ignore USER SUSPEND"
a7f7f624 2540 help
e279b6c1
SR
2541 This option will ignore USER SUSPEND requests. On machines with a
2542 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2543 series notebooks, it is necessary to say Y because of a BIOS bug.
2544
2545config APM_DO_ENABLE
2546 bool "Enable PM at boot time"
a7f7f624 2547 help
e279b6c1
SR
2548 Enable APM features at boot time. From page 36 of the APM BIOS
2549 specification: "When disabled, the APM BIOS does not automatically
2550 power manage devices, enter the Standby State, enter the Suspend
2551 State, or take power saving steps in response to CPU Idle calls."
2552 This driver will make CPU Idle calls when Linux is idle (unless this
2553 feature is turned off -- see "Do CPU IDLE calls", below). This
2554 should always save battery power, but more complicated APM features
2555 will be dependent on your BIOS implementation. You may need to turn
2556 this option off if your computer hangs at boot time when using APM
2557 support, or if it beeps continuously instead of suspending. Turn
2558 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2559 T400CDT. This is off by default since most machines do fine without
2560 this feature.
2561
2562config APM_CPU_IDLE
dd8af076 2563 depends on CPU_IDLE
e279b6c1 2564 bool "Make CPU Idle calls when idle"
a7f7f624 2565 help
e279b6c1
SR
2566 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2567 On some machines, this can activate improved power savings, such as
2568 a slowed CPU clock rate, when the machine is idle. These idle calls
2569 are made after the idle loop has run for some length of time (e.g.,
2570 333 mS). On some machines, this will cause a hang at boot time or
2571 whenever the CPU becomes idle. (On machines with more than one CPU,
2572 this option does nothing.)
2573
2574config APM_DISPLAY_BLANK
2575 bool "Enable console blanking using APM"
a7f7f624 2576 help
e279b6c1
SR
2577 Enable console blanking using the APM. Some laptops can use this to
2578 turn off the LCD backlight when the screen blanker of the Linux
2579 virtual console blanks the screen. Note that this is only used by
2580 the virtual console screen blanker, and won't turn off the backlight
2581 when using the X Window system. This also doesn't have anything to
2582 do with your VESA-compliant power-saving monitor. Further, this
2583 option doesn't work for all laptops -- it might not turn off your
2584 backlight at all, or it might print a lot of errors to the console,
2585 especially if you are using gpm.
2586
2587config APM_ALLOW_INTS
2588 bool "Allow interrupts during APM BIOS calls"
a7f7f624 2589 help
e279b6c1
SR
2590 Normally we disable external interrupts while we are making calls to
2591 the APM BIOS as a measure to lessen the effects of a badly behaving
2592 BIOS implementation. The BIOS should reenable interrupts if it
2593 needs to. Unfortunately, some BIOSes do not -- especially those in
2594 many of the newer IBM Thinkpads. If you experience hangs when you
2595 suspend, try setting this to Y. Otherwise, say N.
2596
e279b6c1
SR
2597endif # APM
2598
bb0a56ec 2599source "drivers/cpufreq/Kconfig"
e279b6c1
SR
2600
2601source "drivers/cpuidle/Kconfig"
2602
27471fdb
AH
2603source "drivers/idle/Kconfig"
2604
e279b6c1
SR
2605endmenu
2606
e279b6c1
SR
2607menu "Bus options (PCI etc.)"
2608
e279b6c1
SR
2609choice
2610 prompt "PCI access mode"
efefa6f6 2611 depends on X86_32 && PCI
e279b6c1 2612 default PCI_GOANY
a7f7f624 2613 help
e279b6c1
SR
2614 On PCI systems, the BIOS can be used to detect the PCI devices and
2615 determine their configuration. However, some old PCI motherboards
2616 have BIOS bugs and may crash if this is done. Also, some embedded
2617 PCI-based systems don't have any BIOS at all. Linux can also try to
2618 detect the PCI hardware directly without using the BIOS.
2619
2620 With this option, you can specify how Linux should detect the
2621 PCI devices. If you choose "BIOS", the BIOS will be used,
2622 if you choose "Direct", the BIOS won't be used, and if you
2623 choose "MMConfig", then PCI Express MMCONFIG will be used.
2624 If you choose "Any", the kernel will try MMCONFIG, then the
2625 direct access method and falls back to the BIOS if that doesn't
2626 work. If unsure, go with the default, which is "Any".
2627
2628config PCI_GOBIOS
2629 bool "BIOS"
2630
2631config PCI_GOMMCONFIG
2632 bool "MMConfig"
2633
2634config PCI_GODIRECT
2635 bool "Direct"
2636
3ef0e1f8 2637config PCI_GOOLPC
76fb6570 2638 bool "OLPC XO-1"
3ef0e1f8
AS
2639 depends on OLPC
2640
2bdd1b03
AS
2641config PCI_GOANY
2642 bool "Any"
2643
e279b6c1
SR
2644endchoice
2645
2646config PCI_BIOS
3c2362e6 2647 def_bool y
efefa6f6 2648 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
e279b6c1
SR
2649
2650# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2651config PCI_DIRECT
3c2362e6 2652 def_bool y
0aba496f 2653 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
e279b6c1
SR
2654
2655config PCI_MMCONFIG
b45c9f36
JK
2656 bool "Support mmconfig PCI config space access" if X86_64
2657 default y
4590d98f 2658 depends on PCI && (ACPI || JAILHOUSE_GUEST)
b45c9f36 2659 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
e279b6c1 2660
3ef0e1f8 2661config PCI_OLPC
2bdd1b03
AS
2662 def_bool y
2663 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
3ef0e1f8 2664
b5401a96
AN
2665config PCI_XEN
2666 def_bool y
2667 depends on PCI && XEN
b5401a96 2668
8364e1f8
JK
2669config MMCONF_FAM10H
2670 def_bool y
2671 depends on X86_64 && PCI_MMCONFIG && ACPI
e279b6c1 2672
3f6ea84a 2673config PCI_CNB20LE_QUIRK
6a108a14 2674 bool "Read CNB20LE Host Bridge Windows" if EXPERT
6ea30386 2675 depends on PCI
3f6ea84a
IS
2676 help
2677 Read the PCI windows out of the CNB20LE host bridge. This allows
2678 PCI hotplug to work on systems with the CNB20LE chipset which do
2679 not have ACPI.
2680
64a5fed6
BH
2681 There's no public spec for this chipset, and this functionality
2682 is known to be incomplete.
2683
2684 You should say N unless you know you need this.
2685
3a495511 2686config ISA_BUS
17a2a129 2687 bool "ISA bus support on modern systems" if EXPERT
3a495511 2688 help
17a2a129
WBG
2689 Expose ISA bus device drivers and options available for selection and
2690 configuration. Enable this option if your target machine has an ISA
2691 bus. ISA is an older system, displaced by PCI and newer bus
2692 architectures -- if your target machine is modern, it probably does
2693 not have an ISA bus.
3a495511
WBG
2694
2695 If unsure, say N.
2696
1c00f016 2697# x86_64 have no ISA slots, but can have ISA-style DMA.
e279b6c1 2698config ISA_DMA_API
1c00f016
DR
2699 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2700 default y
2701 help
2702 Enables ISA-style DMA support for devices requiring such controllers.
2703 If unsure, say Y.
e279b6c1 2704
51e68d05
LT
2705if X86_32
2706
e279b6c1
SR
2707config ISA
2708 bool "ISA support"
a7f7f624 2709 help
e279b6c1
SR
2710 Find out whether you have ISA slots on your motherboard. ISA is the
2711 name of a bus system, i.e. the way the CPU talks to the other stuff
2712 inside your box. Other bus systems are PCI, EISA, MicroChannel
2713 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2714 newer boards don't support it. If you have ISA, say Y, otherwise N.
2715
e279b6c1
SR
2716config SCx200
2717 tristate "NatSemi SCx200 support"
a7f7f624 2718 help
e279b6c1
SR
2719 This provides basic support for National Semiconductor's
2720 (now AMD's) Geode processors. The driver probes for the
2721 PCI-IDs of several on-chip devices, so its a good dependency
2722 for other scx200_* drivers.
2723
2724 If compiled as a module, the driver is named scx200.
2725
2726config SCx200HR_TIMER
2727 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
592913ec 2728 depends on SCx200
e279b6c1 2729 default y
a7f7f624 2730 help
e279b6c1
SR
2731 This driver provides a clocksource built upon the on-chip
2732 27MHz high-resolution timer. Its also a workaround for
2733 NSC Geode SC-1100's buggy TSC, which loses time when the
2734 processor goes idle (as is done by the scheduler). The
2735 other workaround is idle=poll boot option.
2736
3ef0e1f8
AS
2737config OLPC
2738 bool "One Laptop Per Child support"
54008979 2739 depends on !X86_PAE
3c554946 2740 select GPIOLIB
dc3119e7 2741 select OF
45bb1674 2742 select OF_PROMTREE
b4e51854 2743 select IRQ_DOMAIN
0c3d931b 2744 select OLPC_EC
a7f7f624 2745 help
3ef0e1f8
AS
2746 Add support for detecting the unique features of the OLPC
2747 XO hardware.
2748
a3128588
DD
2749config OLPC_XO1_PM
2750 bool "OLPC XO-1 Power Management"
fa112cf1 2751 depends on OLPC && MFD_CS5535=y && PM_SLEEP
a7f7f624 2752 help
97c4cb71 2753 Add support for poweroff and suspend of the OLPC XO-1 laptop.
bf1ebf00 2754
cfee9597
DD
2755config OLPC_XO1_RTC
2756 bool "OLPC XO-1 Real Time Clock"
2757 depends on OLPC_XO1_PM && RTC_DRV_CMOS
a7f7f624 2758 help
cfee9597
DD
2759 Add support for the XO-1 real time clock, which can be used as a
2760 programmable wakeup source.
2761
7feda8e9
DD
2762config OLPC_XO1_SCI
2763 bool "OLPC XO-1 SCI extras"
92e830f2 2764 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
ed8e47fe 2765 depends on INPUT=y
d8d01a63 2766 select POWER_SUPPLY
a7f7f624 2767 help
7feda8e9 2768 Add support for SCI-based features of the OLPC XO-1 laptop:
7bc74b3d 2769 - EC-driven system wakeups
7feda8e9 2770 - Power button
7bc74b3d 2771 - Ebook switch
2cf2baea 2772 - Lid switch
e1040ac6
DD
2773 - AC adapter status updates
2774 - Battery status updates
7feda8e9 2775
a0f30f59
DD
2776config OLPC_XO15_SCI
2777 bool "OLPC XO-1.5 SCI extras"
d8d01a63
DD
2778 depends on OLPC && ACPI
2779 select POWER_SUPPLY
a7f7f624 2780 help
a0f30f59
DD
2781 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2782 - EC-driven system wakeups
2783 - AC adapter status updates
2784 - Battery status updates
bf1ebf00 2785
d4f3e350
EW
2786config ALIX
2787 bool "PCEngines ALIX System Support (LED setup)"
2788 select GPIOLIB
a7f7f624 2789 help
d4f3e350
EW
2790 This option enables system support for the PCEngines ALIX.
2791 At present this just sets up LEDs for GPIO control on
2792 ALIX2/3/6 boards. However, other system specific setup should
2793 get added here.
2794
2795 Note: You must still enable the drivers for GPIO and LED support
2796 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2797
2798 Note: You have to set alix.force=1 for boards with Award BIOS.
2799
da4e3302
PP
2800config NET5501
2801 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2802 select GPIOLIB
a7f7f624 2803 help
da4e3302
PP
2804 This option enables system support for the Soekris Engineering net5501.
2805
3197059a
PP
2806config GEOS
2807 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2808 select GPIOLIB
2809 depends on DMI
a7f7f624 2810 help
3197059a
PP
2811 This option enables system support for the Traverse Technologies GEOS.
2812
7d029125
VD
2813config TS5500
2814 bool "Technologic Systems TS-5500 platform support"
2815 depends on MELAN
2816 select CHECK_SIGNATURE
2817 select NEW_LEDS
2818 select LEDS_CLASS
a7f7f624 2819 help
7d029125
VD
2820 This option enables system support for the Technologic Systems TS-5500.
2821
bc0120fd
SR
2822endif # X86_32
2823
23ac4ae8 2824config AMD_NB
e279b6c1 2825 def_bool y
0e152cd7 2826 depends on CPU_SUP_AMD && PCI
e279b6c1 2827
e279b6c1
SR
2828endmenu
2829
1572497c 2830menu "Binary Emulations"
e279b6c1
SR
2831
2832config IA32_EMULATION
2833 bool "IA32 Emulation"
2834 depends on X86_64
39f88911 2835 select ARCH_WANT_OLD_COMPAT_IPC
d1603990 2836 select BINFMT_ELF
39f88911 2837 select COMPAT_OLD_SIGACTION
a7f7f624 2838 help
5fd92e65
L
2839 Include code to run legacy 32-bit programs under a
2840 64-bit kernel. You should likely turn this on, unless you're
2841 100% sure that you don't have any 32-bit programs left.
e279b6c1 2842
83a44a4f 2843config X86_X32_ABI
6ea30386 2844 bool "x32 ABI for 64-bit mode"
9b54050b 2845 depends on X86_64
aaeed6ec
NC
2846 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2847 # compressed debug sections to x86_x32 properly:
2848 # https://github.com/ClangBuiltLinux/linux/issues/514
2849 # https://github.com/ClangBuiltLinux/linux/issues/1141
2850 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
a7f7f624 2851 help
5fd92e65
L
2852 Include code to run binaries for the x32 native 32-bit ABI
2853 for 64-bit processors. An x32 process gets access to the
2854 full 64-bit register file and wide data path while leaving
2855 pointers at 32 bits for smaller memory footprint.
2856
953fee1d
IM
2857config COMPAT_32
2858 def_bool y
2859 depends on IA32_EMULATION || X86_32
2860 select HAVE_UID16
2861 select OLD_SIGSUSPEND3
2862
e279b6c1 2863config COMPAT
3c2362e6 2864 def_bool y
83a44a4f 2865 depends on IA32_EMULATION || X86_X32_ABI
e279b6c1
SR
2866
2867config COMPAT_FOR_U64_ALIGNMENT
3120e25e 2868 def_bool y
a9251280 2869 depends on COMPAT
ee009e4a 2870
e279b6c1
SR
2871endmenu
2872
e5beae16
KP
2873config HAVE_ATOMIC_IOMAP
2874 def_bool y
2875 depends on X86_32
2876
edf88417 2877source "arch/x86/kvm/Kconfig"
5e8ebd84
JD
2878
2879source "arch/x86/Kconfig.assembler"