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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
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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
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.
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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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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
316d097c 79 select ARCH_HAS_FILTER_PGPROT
6974f0c4 80 select ARCH_HAS_FORTIFY_SOURCE
957e3fac 81 select ARCH_HAS_GCOV_PROFILE_ALL
bece04b5 82 select ARCH_HAS_KCOV if X86_64
0c9c1d56 83 select ARCH_HAS_MEM_ENCRYPT
10bcc80e 84 select ARCH_HAS_MEMBARRIER_SYNC_CORE
0ebeea8c 85 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
c763ea26 86 select ARCH_HAS_PMEM_API if X86_64
17596731 87 select ARCH_HAS_PTE_DEVMAP if X86_64
3010a5ea 88 select ARCH_HAS_PTE_SPECIAL
0aed55af 89 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
ec6347bb 90 select ARCH_HAS_COPY_MC if X86_64
d2852a22 91 select ARCH_HAS_SET_MEMORY
d253ca0c 92 select ARCH_HAS_SET_DIRECT_MAP
ad21fc4f
LA
93 select ARCH_HAS_STRICT_KERNEL_RWX
94 select ARCH_HAS_STRICT_MODULE_RWX
ac1ab12a 95 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
25c619e5 96 select ARCH_HAS_SYSCALL_WRAPPER
c6d30853 97 select ARCH_HAS_UBSAN_SANITIZE_ALL
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
2e4ec02b 124 select ARCH_WANT_HUGETLB_PAGE_FREE_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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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
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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
6dafca97 192 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
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
2e9f3bdd 216 select HAVE_KERNEL_BZIP2
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IM
217 select HAVE_KERNEL_GZIP
218 select HAVE_KERNEL_LZ4
2e9f3bdd 219 select HAVE_KERNEL_LZMA
13510997 220 select HAVE_KERNEL_LZO
6471b825 221 select HAVE_KERNEL_XZ
fb46d057 222 select HAVE_KERNEL_ZSTD
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IM
223 select HAVE_KPROBES
224 select HAVE_KPROBES_ON_FTRACE
540adea3 225 select HAVE_FUNCTION_ERROR_INJECTION
6471b825 226 select HAVE_KRETPROBES
f3a112c0 227 select HAVE_RETHOOK
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IM
228 select HAVE_KVM
229 select HAVE_LIVEPATCH if X86_64
0102752e 230 select HAVE_MIXED_BREAKPOINTS_REGS
ee9f8fce 231 select HAVE_MOD_ARCH_SPECIFIC
9f132f7e 232 select HAVE_MOVE_PMD
be37c98d 233 select HAVE_MOVE_PUD
42a0bb3f 234 select HAVE_NMI
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IM
235 select HAVE_OPTPROBES
236 select HAVE_PCSPKR_PLATFORM
237 select HAVE_PERF_EVENTS
c01d4323 238 select HAVE_PERF_EVENTS_NMI
92e5aae4 239 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
eb01d42a 240 select HAVE_PCI
c5e63197 241 select HAVE_PERF_REGS
c5ebcedb 242 select HAVE_PERF_USER_STACK_DUMP
ff2e6d72 243 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
00998085 244 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
6471b825 245 select HAVE_REGS_AND_STACK_ACCESS_API
6415b38b 246 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
3c88ee19 247 select HAVE_FUNCTION_ARG_ACCESS_API
7ecd19cf 248 select HAVE_SETUP_PER_CPU_AREA
cd1a41ce 249 select HAVE_SOFTIRQ_ON_OWN_STACK
d148eac0 250 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
c763ea26 251 select HAVE_STACK_VALIDATION if X86_64
e6d6c071 252 select HAVE_STATIC_CALL
1e7e4788 253 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
99cf983c 254 select HAVE_PREEMPT_DYNAMIC_CALL
d6761b8f 255 select HAVE_RSEQ
6471b825 256 select HAVE_SYSCALL_TRACEPOINTS
6471b825 257 select HAVE_UNSTABLE_SCHED_CLOCK
7c68af6e 258 select HAVE_USER_RETURN_NOTIFIER
7ac87074 259 select HAVE_GENERIC_VDSO
05736e4a 260 select HOTPLUG_SMT if SMP
c0185808 261 select IRQ_FORCED_THREADING
7ecd19cf
KW
262 select NEED_PER_CPU_EMBED_FIRST_CHUNK
263 select NEED_PER_CPU_PAGE_FIRST_CHUNK
86596f0a 264 select NEED_SG_DMA_LENGTH
2eac9c2d 265 select PCI_DOMAINS if PCI
625210cf 266 select PCI_LOCKLESS_CONFIG if PCI
6471b825 267 select PERF_EVENTS
3195ef59 268 select RTC_LIB
d6faca40 269 select RTC_MC146818_LIB
6471b825 270 select SPARSE_IRQ
83fe27ea 271 select SRCU
1e7e4788 272 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
6471b825 273 select SYSCTL_EXCEPTION_TRACE
15f4eae7 274 select THREAD_INFO_IN_TASK
4aae683f 275 select TRACE_IRQFLAGS_SUPPORT
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IM
276 select USER_STACKTRACE_SUPPORT
277 select VIRT_TO_BUS
3b02a051 278 select HAVE_ARCH_KCSAN if X86_64
6471b825 279 select X86_FEATURE_NAMES if PROC_FS
0c608dad 280 select PROC_PID_ARCH_STATUS if PROC_FS
50468e43 281 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
9e2b4be3 282 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
7d8330a5 283
ba7e4d13 284config INSTRUCTION_DECODER
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JB
285 def_bool y
286 depends on KPROBES || PERF_EVENTS || UPROBES
ba7e4d13 287
51b26ada
LT
288config OUTPUT_FORMAT
289 string
290 default "elf32-i386" if X86_32
291 default "elf64-x86-64" if X86_64
292
8d5fffb9 293config LOCKDEP_SUPPORT
3c2362e6 294 def_bool y
8d5fffb9
SR
295
296config STACKTRACE_SUPPORT
3c2362e6 297 def_bool y
8d5fffb9 298
8d5fffb9 299config MMU
3c2362e6 300 def_bool y
8d5fffb9 301
9e08f57d
DC
302config ARCH_MMAP_RND_BITS_MIN
303 default 28 if 64BIT
304 default 8
305
306config ARCH_MMAP_RND_BITS_MAX
307 default 32 if 64BIT
308 default 16
309
310config ARCH_MMAP_RND_COMPAT_BITS_MIN
311 default 8
312
313config ARCH_MMAP_RND_COMPAT_BITS_MAX
314 default 16
315
8d5fffb9
SR
316config SBUS
317 bool
318
319config GENERIC_ISA_DMA
3120e25e
JB
320 def_bool y
321 depends on ISA_DMA_API
8d5fffb9 322
8d5fffb9 323config GENERIC_BUG
3c2362e6 324 def_bool y
8d5fffb9 325 depends on BUG
b93a531e
JB
326 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
327
328config GENERIC_BUG_RELATIVE_POINTERS
329 bool
8d5fffb9 330
8d5fffb9 331config ARCH_MAY_HAVE_PC_FDC
3120e25e
JB
332 def_bool y
333 depends on ISA_DMA_API
8d5fffb9 334
1032c0ba
SR
335config GENERIC_CALIBRATE_DELAY
336 def_bool y
337
9a0b8415 338config ARCH_HAS_CPU_RELAX
339 def_bool y
340
801e4062
JB
341config ARCH_HIBERNATION_POSSIBLE
342 def_bool y
801e4062 343
d7109fe3
AS
344config ARCH_NR_GPIO
345 int
346 default 1024 if X86_64
347 default 512
348
f4cb5700
JB
349config ARCH_SUSPEND_POSSIBLE
350 def_bool y
f4cb5700 351
8d5fffb9 352config AUDIT_ARCH
e0fd24a3 353 def_bool y if X86_64
8d5fffb9 354
d6f2d75a
AR
355config KASAN_SHADOW_OFFSET
356 hex
357 depends on KASAN
358 default 0xdffffc0000000000
359
69575d38
SW
360config HAVE_INTEL_TXT
361 def_bool y
6ea30386 362 depends on INTEL_IOMMU && ACPI
69575d38 363
6b0c3d44
SR
364config X86_32_SMP
365 def_bool y
366 depends on X86_32 && SMP
367
368config X86_64_SMP
369 def_bool y
370 depends on X86_64 && SMP
371
2b144498
SD
372config ARCH_SUPPORTS_UPROBES
373 def_bool y
374
d20642f0
RH
375config FIX_EARLYCON_MEM
376 def_bool y
377
94d49eb3
KS
378config DYNAMIC_PHYSICAL_MASK
379 bool
380
98233368
KS
381config PGTABLE_LEVELS
382 int
77ef56e4 383 default 5 if X86_5LEVEL
98233368
KS
384 default 4 if X86_64
385 default 3 if X86_PAE
386 default 2
387
2a61f474
MY
388config CC_HAS_SANE_STACKPROTECTOR
389 bool
390 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
391 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
392 help
393 We have to make sure stack protector is unconditionally disabled if
3fb0fdb3
AL
394 the compiler produces broken code or if it does not let us control
395 the segment on 32-bit kernels.
2a61f474 396
506f1d07
SR
397menu "Processor type and features"
398
506f1d07
SR
399config SMP
400 bool "Symmetric multi-processing support"
a7f7f624 401 help
506f1d07 402 This enables support for systems with more than one CPU. If you have
4a474157
RG
403 a system with only one CPU, say N. If you have a system with more
404 than one CPU, say Y.
506f1d07 405
4a474157 406 If you say N here, the kernel will run on uni- and multiprocessor
506f1d07
SR
407 machines, but will use only one CPU of a multiprocessor machine. If
408 you say Y here, the kernel will run on many, but not all,
4a474157 409 uniprocessor machines. On a uniprocessor machine, the kernel
506f1d07
SR
410 will run faster if you say N here.
411
412 Note that if you say Y here and choose architecture "586" or
413 "Pentium" under "Processor family", the kernel will not work on 486
414 architectures. Similarly, multiprocessor kernels for the "PPro"
415 architecture may not work on all Pentium based boards.
416
417 People using multiprocessor machines who say Y here should also say
418 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
419 Management" code will be disabled if you say Y here.
420
cb1aaebe 421 See also <file:Documentation/x86/i386/IO-APIC.rst>,
4f4cfa6c 422 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
506f1d07
SR
423 <http://www.tldp.org/docs.html#howto>.
424
425 If you don't know what to do here, say N.
426
9def39be
JT
427config X86_FEATURE_NAMES
428 bool "Processor feature human-readable names" if EMBEDDED
429 default y
a7f7f624 430 help
9def39be
JT
431 This option compiles in a table of x86 feature bits and corresponding
432 names. This is required to support /proc/cpuinfo and a few kernel
433 messages. You can disable this to save space, at the expense of
434 making those few kernel messages show numeric feature bits instead.
435
436 If in doubt, say Y.
437
06cd9a7d
YL
438config X86_X2APIC
439 bool "Support x2apic"
19e3d60d 440 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
a7f7f624 441 help
06cd9a7d
YL
442 This enables x2apic support on CPUs that have this feature.
443
444 This allows 32-bit apic IDs (so it can support very large systems),
445 and accesses the local apic via MSRs not via mmio.
446
06cd9a7d
YL
447 If you don't know what to do here, say N.
448
6695c85b 449config X86_MPPARSE
4590d98f 450 bool "Enable MPS table" if ACPI
7a527688 451 default y
5ab74722 452 depends on X86_LOCAL_APIC
a7f7f624 453 help
6695c85b
YL
454 For old smp systems that do not have proper acpi support. Newer systems
455 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
6695c85b 456
ddd70cf9 457config GOLDFISH
b03b016f
KK
458 def_bool y
459 depends on X86_GOLDFISH
ddd70cf9 460
76b04384
DW
461config RETPOLINE
462 bool "Avoid speculative indirect branches in kernel"
463 default y
464 help
465 Compile kernel with the retpoline compiler options to guard against
466 kernel-to-user data leaks by avoiding speculative indirect
467 branches. Requires a compiler with -mindirect-branch=thunk-extern
468 support for full protection. The kernel may run slower.
469
e463a09a
PZ
470config CC_HAS_SLS
471 def_bool $(cc-option,-mharden-sls=all)
472
473config SLS
474 bool "Mitigate Straight-Line-Speculation"
475 depends on CC_HAS_SLS && X86_64
476 default n
477 help
478 Compile the kernel with straight-line-speculation options to guard
479 against straight line speculation. The kernel image might be slightly
480 larger.
481
e6d42931
JW
482config X86_CPU_RESCTRL
483 bool "x86 CPU resource control support"
6fe07ce3 484 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
59fe5a77 485 select KERNFS
e79f15a4 486 select PROC_CPU_RESCTRL if PROC_FS
78e99b4a 487 help
e6d42931 488 Enable x86 CPU resource control support.
6fe07ce3
BM
489
490 Provide support for the allocation and monitoring of system resources
491 usage by the CPU.
492
493 Intel calls this Intel Resource Director Technology
494 (Intel(R) RDT). More information about RDT can be found in the
495 Intel x86 Architecture Software Developer Manual.
496
497 AMD calls this AMD Platform Quality of Service (AMD QoS).
498 More information about AMD QoS can be found in the AMD64 Technology
499 Platform Quality of Service Extensions manual.
78e99b4a
FY
500
501 Say N if unsure.
502
8425091f 503if X86_32
a0d0bb4d
RD
504config X86_BIGSMP
505 bool "Support for big SMP systems with more than 8 CPUs"
506 depends on SMP
a7f7f624 507 help
e133f6ea 508 This option is needed for the systems that have more than 8 CPUs.
a0d0bb4d 509
c5c606d9
RT
510config X86_EXTENDED_PLATFORM
511 bool "Support for extended (non-PC) x86 platforms"
512 default y
a7f7f624 513 help
06ac8346
IM
514 If you disable this option then the kernel will only support
515 standard PC platforms. (which covers the vast majority of
516 systems out there.)
517
8425091f
RT
518 If you enable this option then you'll be able to select support
519 for the following (non-PC) 32 bit x86 platforms:
cb7b8023 520 Goldfish (Android emulator)
8425091f 521 AMD Elan
8425091f
RT
522 RDC R-321x SoC
523 SGI 320/540 (Visual Workstation)
83125a3a 524 STA2X11-based (e.g. Northville)
3f4110a4 525 Moorestown MID devices
06ac8346
IM
526
527 If you have one of these systems, or if you want to build a
528 generic distribution kernel, say Y here - otherwise say N.
8425091f 529endif
06ac8346 530
8425091f
RT
531if X86_64
532config X86_EXTENDED_PLATFORM
533 bool "Support for extended (non-PC) x86 platforms"
534 default y
a7f7f624 535 help
8425091f
RT
536 If you disable this option then the kernel will only support
537 standard PC platforms. (which covers the vast majority of
538 systems out there.)
539
540 If you enable this option then you'll be able to select support
541 for the following (non-PC) 64 bit x86 platforms:
44b111b5 542 Numascale NumaChip
8425091f
RT
543 ScaleMP vSMP
544 SGI Ultraviolet
545
546 If you have one of these systems, or if you want to build a
547 generic distribution kernel, say Y here - otherwise say N.
548endif
c5c606d9
RT
549# This is an alphabetically sorted list of 64 bit extended platforms
550# Please maintain the alphabetic order if and when there are additions
44b111b5
SP
551config X86_NUMACHIP
552 bool "Numascale NumaChip"
553 depends on X86_64
554 depends on X86_EXTENDED_PLATFORM
555 depends on NUMA
556 depends on SMP
557 depends on X86_X2APIC
f9726bfd 558 depends on PCI_MMCONFIG
a7f7f624 559 help
44b111b5
SP
560 Adds support for Numascale NumaChip large-SMP systems. Needed to
561 enable more than ~168 cores.
562 If you don't have one of these, you should say N here.
506f1d07 563
c5c606d9
RT
564config X86_VSMP
565 bool "ScaleMP vSMP"
6276a074 566 select HYPERVISOR_GUEST
c5c606d9
RT
567 select PARAVIRT
568 depends on X86_64 && PCI
569 depends on X86_EXTENDED_PLATFORM
ead91d4b 570 depends on SMP
a7f7f624 571 help
c5c606d9
RT
572 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
573 supposed to run on these EM64T-based machines. Only choose this option
574 if you have one of these machines.
5e3a77e9 575
03b48632
NP
576config X86_UV
577 bool "SGI Ultraviolet"
578 depends on X86_64
c5c606d9 579 depends on X86_EXTENDED_PLATFORM
54c28d29 580 depends on NUMA
1ecb4ae5 581 depends on EFI
c2209ea5 582 depends on KEXEC_CORE
9d6c26e7 583 depends on X86_X2APIC
1222e564 584 depends on PCI
a7f7f624 585 help
03b48632
NP
586 This option is needed in order to support SGI Ultraviolet systems.
587 If you don't have one of these, you should say N here.
588
c5c606d9
RT
589# Following is an alphabetically sorted list of 32 bit extended platforms
590# Please maintain the alphabetic order if and when there are additions
506f1d07 591
ddd70cf9 592config X86_GOLDFISH
b03b016f
KK
593 bool "Goldfish (Virtual Platform)"
594 depends on X86_EXTENDED_PLATFORM
a7f7f624 595 help
ddd70cf9
JN
596 Enable support for the Goldfish virtual platform used primarily
597 for Android development. Unless you are building for the Android
598 Goldfish emulator say N here.
599
c751e17b
TG
600config X86_INTEL_CE
601 bool "CE4100 TV platform"
602 depends on PCI
603 depends on PCI_GODIRECT
6084a6e2 604 depends on X86_IO_APIC
c751e17b
TG
605 depends on X86_32
606 depends on X86_EXTENDED_PLATFORM
37bc9f50 607 select X86_REBOOTFIXUPS
da6b737b
SAS
608 select OF
609 select OF_EARLY_FLATTREE
a7f7f624 610 help
c751e17b
TG
611 Select for the Intel CE media processor (CE4100) SOC.
612 This option compiles in support for the CE4100 SOC for settop
613 boxes and media devices.
614
4cb9b00f 615config X86_INTEL_MID
43605ef1 616 bool "Intel MID platform support"
43605ef1 617 depends on X86_EXTENDED_PLATFORM
edc6bc78 618 depends on X86_PLATFORM_DEVICES
1ea7c673 619 depends on PCI
3fda5bb4 620 depends on X86_64 || (PCI_GOANY && X86_32)
1ea7c673 621 depends on X86_IO_APIC
4cb9b00f 622 select I2C
7c9c3a1e 623 select DW_APB_TIMER
54b34aa0 624 select INTEL_SCU_PCI
a7f7f624 625 help
4cb9b00f
DC
626 Select to build a kernel capable of supporting Intel MID (Mobile
627 Internet Device) platform systems which do not have the PCI legacy
628 interfaces. If you are building for a PC class system say N here.
1ea7c673 629
4cb9b00f
DC
630 Intel MID platforms are based on an Intel processor and chipset which
631 consume less power than most of the x86 derivatives.
43605ef1 632
8bbc2a13
BD
633config X86_INTEL_QUARK
634 bool "Intel Quark platform support"
635 depends on X86_32
636 depends on X86_EXTENDED_PLATFORM
637 depends on X86_PLATFORM_DEVICES
638 depends on X86_TSC
639 depends on PCI
640 depends on PCI_GOANY
641 depends on X86_IO_APIC
642 select IOSF_MBI
643 select INTEL_IMR
9ab6eb51 644 select COMMON_CLK
a7f7f624 645 help
8bbc2a13
BD
646 Select to include support for Quark X1000 SoC.
647 Say Y here if you have a Quark based system such as the Arduino
648 compatible Intel Galileo.
649
3d48aab1
MW
650config X86_INTEL_LPSS
651 bool "Intel Low Power Subsystem Support"
5962dd22 652 depends on X86 && ACPI && PCI
3d48aab1 653 select COMMON_CLK
0f531431 654 select PINCTRL
eebb3e8d 655 select IOSF_MBI
a7f7f624 656 help
3d48aab1
MW
657 Select to build support for Intel Low Power Subsystem such as
658 found on Intel Lynxpoint PCH. Selecting this option enables
0f531431
MN
659 things like clock tree (common clock framework) and pincontrol
660 which are needed by the LPSS peripheral drivers.
3d48aab1 661
92082a88
KX
662config X86_AMD_PLATFORM_DEVICE
663 bool "AMD ACPI2Platform devices support"
664 depends on ACPI
665 select COMMON_CLK
666 select PINCTRL
a7f7f624 667 help
92082a88
KX
668 Select to interpret AMD specific ACPI device to platform device
669 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
670 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
671 implemented under PINCTRL subsystem.
672
ced3ce76
DB
673config IOSF_MBI
674 tristate "Intel SoC IOSF Sideband support for SoC platforms"
675 depends on PCI
a7f7f624 676 help
ced3ce76
DB
677 This option enables sideband register access support for Intel SoC
678 platforms. On these platforms the IOSF sideband is used in lieu of
679 MSR's for some register accesses, mostly but not limited to thermal
680 and power. Drivers may query the availability of this device to
681 determine if they need the sideband in order to work on these
682 platforms. The sideband is available on the following SoC products.
683 This list is not meant to be exclusive.
684 - BayTrail
685 - Braswell
686 - Quark
687
688 You should say Y if you are running a kernel on one of these SoC's.
689
ed2226bd
DB
690config IOSF_MBI_DEBUG
691 bool "Enable IOSF sideband access through debugfs"
692 depends on IOSF_MBI && DEBUG_FS
a7f7f624 693 help
ed2226bd
DB
694 Select this option to expose the IOSF sideband access registers (MCR,
695 MDR, MCRX) through debugfs to write and read register information from
696 different units on the SoC. This is most useful for obtaining device
697 state information for debug and analysis. As this is a general access
698 mechanism, users of this option would have specific knowledge of the
699 device they want to access.
700
701 If you don't require the option or are in doubt, say N.
702
c5c606d9
RT
703config X86_RDC321X
704 bool "RDC R-321x SoC"
506f1d07 705 depends on X86_32
c5c606d9
RT
706 depends on X86_EXTENDED_PLATFORM
707 select M486
708 select X86_REBOOTFIXUPS
a7f7f624 709 help
c5c606d9
RT
710 This option is needed for RDC R-321x system-on-chip, also known
711 as R-8610-(G).
712 If you don't have one of these chips, you should say N here.
713
e0c7ae37 714config X86_32_NON_STANDARD
9c398017
IM
715 bool "Support non-standard 32-bit SMP architectures"
716 depends on X86_32 && SMP
c5c606d9 717 depends on X86_EXTENDED_PLATFORM
a7f7f624 718 help
b5660ba7
PA
719 This option compiles in the bigsmp and STA2X11 default
720 subarchitectures. It is intended for a generic binary
721 kernel. If you select them all, kernel will probe it one by
722 one and will fallback to default.
d49c4288 723
c5c606d9 724# Alphabetically sorted list of Non standard 32 bit platforms
d49c4288 725
d949f36f 726config X86_SUPPORTS_MEMORY_FAILURE
6fc108a0 727 def_bool y
d949f36f
LT
728 # MCE code calls memory_failure():
729 depends on X86_MCE
730 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
d949f36f
LT
731 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
732 depends on X86_64 || !SPARSEMEM
733 select ARCH_SUPPORTS_MEMORY_FAILURE
d949f36f 734
83125a3a
AR
735config STA2X11
736 bool "STA2X11 Companion Chip Support"
737 depends on X86_32_NON_STANDARD && PCI
83125a3a
AR
738 select SWIOTLB
739 select MFD_STA2X11
0145071b 740 select GPIOLIB
a7f7f624 741 help
83125a3a
AR
742 This adds support for boards based on the STA2X11 IO-Hub,
743 a.k.a. "ConneXt". The chip is used in place of the standard
744 PC chipset, so all "standard" peripherals are missing. If this
745 option is selected the kernel will still be able to boot on
746 standard PC machines.
747
82148d1d
S
748config X86_32_IRIS
749 tristate "Eurobraille/Iris poweroff module"
750 depends on X86_32
a7f7f624 751 help
82148d1d
S
752 The Iris machines from EuroBraille do not have APM or ACPI support
753 to shut themselves down properly. A special I/O sequence is
754 needed to do so, which is what this module does at
755 kernel shutdown.
756
757 This is only for Iris machines from EuroBraille.
758
759 If unused, say N.
760
ae1e9130 761config SCHED_OMIT_FRAME_POINTER
3c2362e6
HH
762 def_bool y
763 prompt "Single-depth WCHAN output"
a87d0914 764 depends on X86
a7f7f624 765 help
506f1d07
SR
766 Calculate simpler /proc/<PID>/wchan values. If this option
767 is disabled then wchan values will recurse back to the
768 caller function. This provides more accurate wchan values,
769 at the expense of slightly more scheduling overhead.
770
771 If in doubt, say "Y".
772
6276a074
BP
773menuconfig HYPERVISOR_GUEST
774 bool "Linux guest support"
a7f7f624 775 help
6276a074
BP
776 Say Y here to enable options for running Linux under various hyper-
777 visors. This option enables basic hypervisor detection and platform
778 setup.
506f1d07 779
6276a074
BP
780 If you say N, all options in this submenu will be skipped and
781 disabled, and Linux guest support won't be built in.
506f1d07 782
6276a074 783if HYPERVISOR_GUEST
506f1d07 784
e61bd94a
EPH
785config PARAVIRT
786 bool "Enable paravirtualization code"
a0e2bf7c 787 depends on HAVE_STATIC_CALL
a7f7f624 788 help
e61bd94a
EPH
789 This changes the kernel so it can modify itself when it is run
790 under a hypervisor, potentially improving performance significantly
791 over full virtualization. However, when run without a hypervisor
792 the kernel is theoretically slower and slightly larger.
793
c00a280a
JG
794config PARAVIRT_XXL
795 bool
796
6276a074
BP
797config PARAVIRT_DEBUG
798 bool "paravirt-ops debugging"
799 depends on PARAVIRT && DEBUG_KERNEL
a7f7f624 800 help
6276a074
BP
801 Enable to debug paravirt_ops internals. Specifically, BUG if
802 a paravirt_op is missing when it is called.
803
b4ecc126
JF
804config PARAVIRT_SPINLOCKS
805 bool "Paravirtualization layer for spinlocks"
6ea30386 806 depends on PARAVIRT && SMP
a7f7f624 807 help
b4ecc126
JF
808 Paravirtualized spinlocks allow a pvops backend to replace the
809 spinlock implementation with something virtualization-friendly
810 (for example, block the virtual CPU rather than spinning).
811
4c4e4f61
R
812 It has a minimal impact on native kernels and gives a nice performance
813 benefit on paravirtualized KVM / Xen kernels.
b4ecc126 814
4c4e4f61 815 If you are unsure how to answer this question, answer Y.
b4ecc126 816
ecca2502
ZY
817config X86_HV_CALLBACK_VECTOR
818 def_bool n
819
6276a074 820source "arch/x86/xen/Kconfig"
7af192c9 821
6276a074
BP
822config KVM_GUEST
823 bool "KVM Guest support (including kvmclock)"
824 depends on PARAVIRT
825 select PARAVIRT_CLOCK
a1c4423b 826 select ARCH_CPUIDLE_HALTPOLL
b1d40575 827 select X86_HV_CALLBACK_VECTOR
6276a074 828 default y
a7f7f624 829 help
6276a074
BP
830 This option enables various optimizations for running under the KVM
831 hypervisor. It includes a paravirtualized clock, so that instead
832 of relying on a PIT (or probably other) emulation by the
833 underlying device model, the host provides the guest with
834 timing infrastructure such as time of day, and system time
506f1d07 835
a1c4423b 836config ARCH_CPUIDLE_HALTPOLL
b03b016f
KK
837 def_bool n
838 prompt "Disable host haltpoll when loading haltpoll driver"
839 help
a1c4423b
MT
840 If virtualized under KVM, disable host haltpoll.
841
7733607f
MW
842config PVH
843 bool "Support for running PVH guests"
a7f7f624 844 help
7733607f
MW
845 This option enables the PVH entry point for guest virtual machines
846 as specified in the x86/HVM direct boot ABI.
847
6276a074
BP
848config PARAVIRT_TIME_ACCOUNTING
849 bool "Paravirtual steal time accounting"
850 depends on PARAVIRT
a7f7f624 851 help
6276a074
BP
852 Select this option to enable fine granularity task steal time
853 accounting. Time spent executing other tasks in parallel with
854 the current vCPU is discounted from the vCPU power. To account for
855 that, there can be a small performance impact.
856
857 If in doubt, say N here.
858
859config PARAVIRT_CLOCK
860 bool
97349135 861
4a362601
JK
862config JAILHOUSE_GUEST
863 bool "Jailhouse non-root cell support"
abde587b 864 depends on X86_64 && PCI
87e65d05 865 select X86_PM_TIMER
a7f7f624 866 help
4a362601
JK
867 This option allows to run Linux as guest in a Jailhouse non-root
868 cell. You can leave this option disabled if you only want to start
869 Jailhouse and run Linux afterwards in the root cell.
870
ec7972c9
ZY
871config ACRN_GUEST
872 bool "ACRN Guest support"
873 depends on X86_64
498ad393 874 select X86_HV_CALLBACK_VECTOR
ec7972c9
ZY
875 help
876 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
877 a flexible, lightweight reference open-source hypervisor, built with
878 real-time and safety-criticality in mind. It is built for embedded
879 IOT with small footprint and real-time features. More details can be
880 found in https://projectacrn.org/.
881
6276a074 882endif #HYPERVISOR_GUEST
97349135 883
506f1d07
SR
884source "arch/x86/Kconfig.cpu"
885
886config HPET_TIMER
3c2362e6 887 def_bool X86_64
506f1d07 888 prompt "HPET Timer Support" if X86_32
a7f7f624 889 help
8f9ca475
IM
890 Use the IA-PC HPET (High Precision Event Timer) to manage
891 time in preference to the PIT and RTC, if a HPET is
892 present.
893 HPET is the next generation timer replacing legacy 8254s.
894 The HPET provides a stable time base on SMP
895 systems, unlike the TSC, but it is more expensive to access,
4e7f9df2
MT
896 as it is off-chip. The interface used is documented
897 in the HPET spec, revision 1.
506f1d07 898
8f9ca475
IM
899 You can safely choose Y here. However, HPET will only be
900 activated if the platform and the BIOS support this feature.
901 Otherwise the 8254 will be used for timing services.
506f1d07 902
8f9ca475 903 Choose N to continue using the legacy 8254 timer.
506f1d07
SR
904
905config HPET_EMULATE_RTC
3c2362e6 906 def_bool y
3228e1dc 907 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
506f1d07 908
6a108a14 909# Mark as expert because too many people got it wrong.
506f1d07 910# The code disables itself when not needed.
7ae9392c
TP
911config DMI
912 default y
cf074402 913 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
6a108a14 914 bool "Enable DMI scanning" if EXPERT
a7f7f624 915 help
7ae9392c
TP
916 Enabled scanning of DMI to identify machine quirks. Say Y
917 here unless you have verified that your setup is not
918 affected by entries in the DMI blacklist. Required by PNP
919 BIOS code.
920
506f1d07 921config GART_IOMMU
38901f1c 922 bool "Old AMD GART IOMMU support"
2f9237d4 923 select DMA_OPS
a4ce5a48 924 select IOMMU_HELPER
506f1d07 925 select SWIOTLB
23ac4ae8 926 depends on X86_64 && PCI && AMD_NB
a7f7f624 927 help
ced3c42c
IM
928 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
929 GART based hardware IOMMUs.
930
931 The GART supports full DMA access for devices with 32-bit access
932 limitations, on systems with more than 3 GB. This is usually needed
933 for USB, sound, many IDE/SATA chipsets and some other devices.
934
935 Newer systems typically have a modern AMD IOMMU, supported via
936 the CONFIG_AMD_IOMMU=y config option.
937
938 In normal configurations this driver is only active when needed:
939 there's more than 3 GB of memory and the system contains a
940 32-bit limited device.
941
942 If unsure, say Y.
506f1d07 943
1184dc2f 944config MAXSMP
ddb0c5a6 945 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
6ea30386 946 depends on X86_64 && SMP && DEBUG_KERNEL
36f5101a 947 select CPUMASK_OFFSTACK
a7f7f624 948 help
ddb0c5a6 949 Enable maximum number of CPUS and NUMA Nodes for this architecture.
1184dc2f 950 If unsure, say N.
506f1d07 951
aec6487e
IM
952#
953# The maximum number of CPUs supported:
954#
955# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
956# and which can be configured interactively in the
957# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
958#
959# The ranges are different on 32-bit and 64-bit kernels, depending on
960# hardware capabilities and scalability features of the kernel.
961#
962# ( If MAXSMP is enabled we just use the highest possible value and disable
963# interactive configuration. )
964#
965
966config NR_CPUS_RANGE_BEGIN
a0d0bb4d 967 int
aec6487e
IM
968 default NR_CPUS_RANGE_END if MAXSMP
969 default 1 if !SMP
970 default 2
a0d0bb4d 971
aec6487e 972config NR_CPUS_RANGE_END
a0d0bb4d 973 int
aec6487e
IM
974 depends on X86_32
975 default 64 if SMP && X86_BIGSMP
976 default 8 if SMP && !X86_BIGSMP
977 default 1 if !SMP
a0d0bb4d 978
aec6487e 979config NR_CPUS_RANGE_END
a0d0bb4d 980 int
aec6487e 981 depends on X86_64
1edae1ae
SW
982 default 8192 if SMP && CPUMASK_OFFSTACK
983 default 512 if SMP && !CPUMASK_OFFSTACK
aec6487e 984 default 1 if !SMP
a0d0bb4d 985
aec6487e 986config NR_CPUS_DEFAULT
a0d0bb4d
RD
987 int
988 depends on X86_32
aec6487e
IM
989 default 32 if X86_BIGSMP
990 default 8 if SMP
991 default 1 if !SMP
a0d0bb4d 992
aec6487e 993config NR_CPUS_DEFAULT
a0d0bb4d
RD
994 int
995 depends on X86_64
aec6487e
IM
996 default 8192 if MAXSMP
997 default 64 if SMP
998 default 1 if !SMP
a0d0bb4d 999
506f1d07 1000config NR_CPUS
36f5101a 1001 int "Maximum number of CPUs" if SMP && !MAXSMP
aec6487e
IM
1002 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1003 default NR_CPUS_DEFAULT
a7f7f624 1004 help
506f1d07 1005 This allows you to specify the maximum number of CPUs which this
bb61ccc7 1006 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
cad14bb9 1007 supported value is 8192, otherwise the maximum value is 512. The
506f1d07
SR
1008 minimum value which makes sense is 2.
1009
aec6487e
IM
1010 This is purely to save memory: each supported CPU adds about 8KB
1011 to the kernel image.
506f1d07 1012
66558b73
TC
1013config SCHED_CLUSTER
1014 bool "Cluster scheduler support"
1015 depends on SMP
1016 default y
1017 help
1018 Cluster scheduler support improves the CPU scheduler's decision
1019 making when dealing with machines that have clusters of CPUs.
1020 Cluster usually means a couple of CPUs which are placed closely
1021 by sharing mid-level caches, last-level cache tags or internal
1022 busses.
1023
506f1d07 1024config SCHED_SMT
dbe73364 1025 def_bool y if SMP
506f1d07
SR
1026
1027config SCHED_MC
3c2362e6
HH
1028 def_bool y
1029 prompt "Multi-core scheduler support"
c8e56d20 1030 depends on SMP
a7f7f624 1031 help
506f1d07
SR
1032 Multi-core scheduler support improves the CPU scheduler's decision
1033 making when dealing with multi-core CPU chips at a cost of slightly
1034 increased overhead in some places. If unsure say N here.
1035
de966cf4
TC
1036config SCHED_MC_PRIO
1037 bool "CPU core priorities scheduler support"
0a21fc12
IM
1038 depends on SCHED_MC && CPU_SUP_INTEL
1039 select X86_INTEL_PSTATE
1040 select CPU_FREQ
de966cf4 1041 default y
a7f7f624 1042 help
0a21fc12
IM
1043 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1044 core ordering determined at manufacturing time, which allows
1045 certain cores to reach higher turbo frequencies (when running
1046 single threaded workloads) than others.
de966cf4 1047
0a21fc12
IM
1048 Enabling this kernel feature teaches the scheduler about
1049 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1050 scheduler's CPU selection logic accordingly, so that higher
1051 overall system performance can be achieved.
de966cf4 1052
0a21fc12 1053 This feature will have no effect on CPUs without this feature.
de966cf4 1054
0a21fc12 1055 If unsure say Y here.
5e76b2ab 1056
30b8b006 1057config UP_LATE_INIT
b03b016f
KK
1058 def_bool y
1059 depends on !SMP && X86_LOCAL_APIC
30b8b006 1060
506f1d07 1061config X86_UP_APIC
50849eef
JB
1062 bool "Local APIC support on uniprocessors" if !PCI_MSI
1063 default PCI_MSI
38a1dfda 1064 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
a7f7f624 1065 help
506f1d07
SR
1066 A local APIC (Advanced Programmable Interrupt Controller) is an
1067 integrated interrupt controller in the CPU. If you have a single-CPU
1068 system which has a processor with a local APIC, you can say Y here to
1069 enable and use it. If you say Y here even though your machine doesn't
1070 have a local APIC, then the kernel will still run with no slowdown at
1071 all. The local APIC supports CPU-generated self-interrupts (timer,
1072 performance counters), and the NMI watchdog which detects hard
1073 lockups.
1074
1075config X86_UP_IOAPIC
1076 bool "IO-APIC support on uniprocessors"
1077 depends on X86_UP_APIC
a7f7f624 1078 help
506f1d07
SR
1079 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1080 SMP-capable replacement for PC-style interrupt controllers. Most
1081 SMP systems and many recent uniprocessor systems have one.
1082
1083 If you have a single-CPU system with an IO-APIC, you can say Y here
1084 to use it. If you say Y here even though your machine doesn't have
1085 an IO-APIC, then the kernel will still run with no slowdown at all.
1086
1087config X86_LOCAL_APIC
3c2362e6 1088 def_bool y
0dbc6078 1089 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
b5dc8e6c 1090 select IRQ_DOMAIN_HIERARCHY
52f518a3 1091 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
506f1d07
SR
1092
1093config X86_IO_APIC
b1da1e71
JB
1094 def_bool y
1095 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
506f1d07 1096
41b9eb26
SA
1097config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1098 bool "Reroute for broken boot IRQs"
41b9eb26 1099 depends on X86_IO_APIC
a7f7f624 1100 help
41b9eb26
SA
1101 This option enables a workaround that fixes a source of
1102 spurious interrupts. This is recommended when threaded
1103 interrupt handling is used on systems where the generation of
1104 superfluous "boot interrupts" cannot be disabled.
1105
1106 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1107 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1108 kernel does during interrupt handling). On chipsets where this
1109 boot IRQ generation cannot be disabled, this workaround keeps
1110 the original IRQ line masked so that only the equivalent "boot
1111 IRQ" is delivered to the CPUs. The workaround also tells the
1112 kernel to set up the IRQ handler on the boot IRQ line. In this
1113 way only one interrupt is delivered to the kernel. Otherwise
1114 the spurious second interrupt may cause the kernel to bring
1115 down (vital) interrupt lines.
1116
1117 Only affects "broken" chipsets. Interrupt sharing may be
1118 increased on these systems.
1119
506f1d07 1120config X86_MCE
bab9bc65 1121 bool "Machine Check / overheating reporting"
648ed940 1122 select GENERIC_ALLOCATOR
e57dbaf7 1123 default y
a7f7f624 1124 help
bab9bc65
AK
1125 Machine Check support allows the processor to notify the
1126 kernel if it detects a problem (e.g. overheating, data corruption).
506f1d07 1127 The action the kernel takes depends on the severity of the problem,
bab9bc65 1128 ranging from warning messages to halting the machine.
4efc0670 1129
5de97c9f
TL
1130config X86_MCELOG_LEGACY
1131 bool "Support for deprecated /dev/mcelog character device"
1132 depends on X86_MCE
a7f7f624 1133 help
5de97c9f
TL
1134 Enable support for /dev/mcelog which is needed by the old mcelog
1135 userspace logging daemon. Consider switching to the new generation
1136 rasdaemon solution.
1137
506f1d07 1138config X86_MCE_INTEL
3c2362e6
HH
1139 def_bool y
1140 prompt "Intel MCE features"
c1ebf835 1141 depends on X86_MCE && X86_LOCAL_APIC
a7f7f624 1142 help
506f1d07
SR
1143 Additional support for intel specific MCE features such as
1144 the thermal monitor.
1145
1146config X86_MCE_AMD
3c2362e6
HH
1147 def_bool y
1148 prompt "AMD MCE features"
f5382de9 1149 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
a7f7f624 1150 help
506f1d07
SR
1151 Additional support for AMD specific MCE features such as
1152 the DRAM Error Threshold.
1153
4efc0670 1154config X86_ANCIENT_MCE
6fc108a0 1155 bool "Support for old Pentium 5 / WinChip machine checks"
c31d9633 1156 depends on X86_32 && X86_MCE
a7f7f624 1157 help
cd13adcc 1158 Include support for machine check handling on old Pentium 5 or WinChip
5065a706 1159 systems. These typically need to be enabled explicitly on the command
cd13adcc 1160 line.
4efc0670 1161
b2762686
AK
1162config X86_MCE_THRESHOLD
1163 depends on X86_MCE_AMD || X86_MCE_INTEL
6fc108a0 1164 def_bool y
b2762686 1165
ea149b36 1166config X86_MCE_INJECT
bc8e80d5 1167 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
ea149b36 1168 tristate "Machine check injector support"
a7f7f624 1169 help
ea149b36
AK
1170 Provide support for injecting machine checks for testing purposes.
1171 If you don't know what a machine check is and you don't do kernel
1172 QA it is safe to say n.
1173
07dc900e 1174source "arch/x86/events/Kconfig"
e633c65a 1175
5aef51c3 1176config X86_LEGACY_VM86
1e642812 1177 bool "Legacy VM86 support"
506f1d07 1178 depends on X86_32
a7f7f624 1179 help
5aef51c3
AL
1180 This option allows user programs to put the CPU into V8086
1181 mode, which is an 80286-era approximation of 16-bit real mode.
1182
1183 Some very old versions of X and/or vbetool require this option
1184 for user mode setting. Similarly, DOSEMU will use it if
1185 available to accelerate real mode DOS programs. However, any
1186 recent version of DOSEMU, X, or vbetool should be fully
1187 functional even without kernel VM86 support, as they will all
1e642812
IM
1188 fall back to software emulation. Nevertheless, if you are using
1189 a 16-bit DOS program where 16-bit performance matters, vm86
1190 mode might be faster than emulation and you might want to
1191 enable this option.
5aef51c3 1192
1e642812
IM
1193 Note that any app that works on a 64-bit kernel is unlikely to
1194 need this option, as 64-bit kernels don't, and can't, support
1195 V8086 mode. This option is also unrelated to 16-bit protected
1196 mode and is not needed to run most 16-bit programs under Wine.
5aef51c3 1197
1e642812
IM
1198 Enabling this option increases the complexity of the kernel
1199 and slows down exception handling a tiny bit.
5aef51c3 1200
1e642812 1201 If unsure, say N here.
5aef51c3
AL
1202
1203config VM86
b03b016f
KK
1204 bool
1205 default X86_LEGACY_VM86
34273f41
PA
1206
1207config X86_16BIT
1208 bool "Enable support for 16-bit segments" if EXPERT
1209 default y
a5b9e5a2 1210 depends on MODIFY_LDT_SYSCALL
a7f7f624 1211 help
34273f41
PA
1212 This option is required by programs like Wine to run 16-bit
1213 protected mode legacy code on x86 processors. Disabling
1214 this option saves about 300 bytes on i386, or around 6K text
1215 plus 16K runtime memory on x86-64,
1216
1217config X86_ESPFIX32
1218 def_bool y
1219 depends on X86_16BIT && X86_32
506f1d07 1220
197725de
PA
1221config X86_ESPFIX64
1222 def_bool y
34273f41 1223 depends on X86_16BIT && X86_64
506f1d07 1224
1ad83c85 1225config X86_VSYSCALL_EMULATION
b03b016f
KK
1226 bool "Enable vsyscall emulation" if EXPERT
1227 default y
1228 depends on X86_64
a7f7f624 1229 help
1ad83c85
AL
1230 This enables emulation of the legacy vsyscall page. Disabling
1231 it is roughly equivalent to booting with vsyscall=none, except
1232 that it will also disable the helpful warning if a program
1233 tries to use a vsyscall. With this option set to N, offending
1234 programs will just segfault, citing addresses of the form
1235 0xffffffffff600?00.
1236
1237 This option is required by many programs built before 2013, and
1238 care should be used even with newer programs if set to N.
1239
1240 Disabling this option saves about 7K of kernel size and
1241 possibly 4K of additional runtime pagetable memory.
1242
111e7b15
TG
1243config X86_IOPL_IOPERM
1244 bool "IOPERM and IOPL Emulation"
a24ca997 1245 default y
a7f7f624 1246 help
111e7b15
TG
1247 This enables the ioperm() and iopl() syscalls which are necessary
1248 for legacy applications.
1249
c8137ace
TG
1250 Legacy IOPL support is an overbroad mechanism which allows user
1251 space aside of accessing all 65536 I/O ports also to disable
1252 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1253 capabilities and permission from potentially active security
1254 modules.
1255
1256 The emulation restricts the functionality of the syscall to
1257 only allowing the full range I/O port access, but prevents the
a24ca997
TG
1258 ability to disable interrupts from user space which would be
1259 granted if the hardware IOPL mechanism would be used.
c8137ace 1260
506f1d07
SR
1261config TOSHIBA
1262 tristate "Toshiba Laptop support"
1263 depends on X86_32
a7f7f624 1264 help
506f1d07
SR
1265 This adds a driver to safely access the System Management Mode of
1266 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1267 not work on models with a Phoenix BIOS. The System Management Mode
1268 is used to set the BIOS and power saving options on Toshiba portables.
1269
1270 For information on utilities to make use of this driver see the
1271 Toshiba Linux utilities web site at:
1272 <http://www.buzzard.org.uk/toshiba/>.
1273
1274 Say Y if you intend to run this kernel on a Toshiba portable.
1275 Say N otherwise.
1276
506f1d07 1277config X86_REBOOTFIXUPS
9ba16087
JB
1278 bool "Enable X86 board specific fixups for reboot"
1279 depends on X86_32
a7f7f624 1280 help
506f1d07
SR
1281 This enables chipset and/or board specific fixups to be done
1282 in order to get reboot to work correctly. This is only needed on
1283 some combinations of hardware and BIOS. The symptom, for which
1284 this config is intended, is when reboot ends with a stalled/hung
1285 system.
1286
1287 Currently, the only fixup is for the Geode machines using
5e3a77e9 1288 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
506f1d07
SR
1289
1290 Say Y if you want to enable the fixup. Currently, it's safe to
1291 enable this option even if you don't need it.
1292 Say N otherwise.
1293
1294config MICROCODE
9a2bc335
BP
1295 bool "CPU microcode loading support"
1296 default y
80030e3d 1297 depends on CPU_SUP_AMD || CPU_SUP_INTEL
a7f7f624 1298 help
506f1d07 1299 If you say Y here, you will be able to update the microcode on
5f9c01aa
BP
1300 Intel and AMD processors. The Intel support is for the IA32 family,
1301 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1302 AMD support is for families 0x10 and later. You will obviously need
1303 the actual microcode binary data itself which is not shipped with
1304 the Linux kernel.
1305
1306 The preferred method to load microcode from a detached initrd is described
cb1aaebe 1307 in Documentation/x86/microcode.rst. For that you need to enable
5f9c01aa
BP
1308 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1309 initrd for microcode blobs.
1310
c508c46e
BG
1311 In addition, you can build the microcode into the kernel. For that you
1312 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1313 config option.
506f1d07 1314
8d86f390 1315config MICROCODE_INTEL
e43f6e67 1316 bool "Intel microcode loading support"
8f9ca475
IM
1317 depends on MICROCODE
1318 default MICROCODE
a7f7f624 1319 help
8f9ca475
IM
1320 This options enables microcode patch loading support for Intel
1321 processors.
1322
b8989db9
A
1323 For the current Intel microcode data package go to
1324 <https://downloadcenter.intel.com> and search for
1325 'Linux Processor Microcode Data File'.
8d86f390 1326
80cc9f10 1327config MICROCODE_AMD
e43f6e67 1328 bool "AMD microcode loading support"
8f9ca475 1329 depends on MICROCODE
a7f7f624 1330 help
8f9ca475
IM
1331 If you select this option, microcode patch loading support for AMD
1332 processors will be enabled.
80cc9f10 1333
8f9ca475 1334config MICROCODE_OLD_INTERFACE
c02f48e0
BP
1335 bool "Ancient loading interface (DEPRECATED)"
1336 default n
506f1d07 1337 depends on MICROCODE
a7f7f624 1338 help
c02f48e0
BP
1339 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1340 which was used by userspace tools like iucode_tool and microcode.ctl.
1341 It is inadequate because it runs too late to be able to properly
1342 load microcode on a machine and it needs special tools. Instead, you
1343 should've switched to the early loading method with the initrd or
cb1aaebe 1344 builtin microcode by now: Documentation/x86/microcode.rst
506f1d07
SR
1345
1346config X86_MSR
1347 tristate "/dev/cpu/*/msr - Model-specific register support"
a7f7f624 1348 help
506f1d07
SR
1349 This device gives privileged processes access to the x86
1350 Model-Specific Registers (MSRs). It is a character device with
1351 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1352 MSR accesses are directed to a specific CPU on multi-processor
1353 systems.
1354
1355config X86_CPUID
1356 tristate "/dev/cpu/*/cpuid - CPU information support"
a7f7f624 1357 help
506f1d07
SR
1358 This device gives processes access to the x86 CPUID instruction to
1359 be executed on a specific processor. It is a character device
1360 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1361 /dev/cpu/31/cpuid.
1362
1363choice
1364 prompt "High Memory Support"
6fc108a0 1365 default HIGHMEM4G
506f1d07
SR
1366 depends on X86_32
1367
1368config NOHIGHMEM
1369 bool "off"
a7f7f624 1370 help
506f1d07
SR
1371 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1372 However, the address space of 32-bit x86 processors is only 4
1373 Gigabytes large. That means that, if you have a large amount of
1374 physical memory, not all of it can be "permanently mapped" by the
1375 kernel. The physical memory that's not permanently mapped is called
1376 "high memory".
1377
1378 If you are compiling a kernel which will never run on a machine with
1379 more than 1 Gigabyte total physical RAM, answer "off" here (default
1380 choice and suitable for most users). This will result in a "3GB/1GB"
1381 split: 3GB are mapped so that each process sees a 3GB virtual memory
1382 space and the remaining part of the 4GB virtual memory space is used
1383 by the kernel to permanently map as much physical memory as
1384 possible.
1385
1386 If the machine has between 1 and 4 Gigabytes physical RAM, then
1387 answer "4GB" here.
1388
1389 If more than 4 Gigabytes is used then answer "64GB" here. This
1390 selection turns Intel PAE (Physical Address Extension) mode on.
1391 PAE implements 3-level paging on IA32 processors. PAE is fully
1392 supported by Linux, PAE mode is implemented on all recent Intel
1393 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1394 then the kernel will not boot on CPUs that don't support PAE!
1395
1396 The actual amount of total physical memory will either be
1397 auto detected or can be forced by using a kernel command line option
1398 such as "mem=256M". (Try "man bootparam" or see the documentation of
1399 your boot loader (lilo or loadlin) about how to pass options to the
1400 kernel at boot time.)
1401
1402 If unsure, say "off".
1403
1404config HIGHMEM4G
1405 bool "4GB"
a7f7f624 1406 help
506f1d07
SR
1407 Select this if you have a 32-bit processor and between 1 and 4
1408 gigabytes of physical RAM.
1409
1410config HIGHMEM64G
1411 bool "64GB"
225bac2d 1412 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
506f1d07 1413 select X86_PAE
a7f7f624 1414 help
506f1d07
SR
1415 Select this if you have a 32-bit processor and more than 4
1416 gigabytes of physical RAM.
1417
1418endchoice
1419
1420choice
6a108a14 1421 prompt "Memory split" if EXPERT
506f1d07
SR
1422 default VMSPLIT_3G
1423 depends on X86_32
a7f7f624 1424 help
506f1d07
SR
1425 Select the desired split between kernel and user memory.
1426
1427 If the address range available to the kernel is less than the
1428 physical memory installed, the remaining memory will be available
1429 as "high memory". Accessing high memory is a little more costly
1430 than low memory, as it needs to be mapped into the kernel first.
1431 Note that increasing the kernel address space limits the range
1432 available to user programs, making the address space there
1433 tighter. Selecting anything other than the default 3G/1G split
1434 will also likely make your kernel incompatible with binary-only
1435 kernel modules.
1436
1437 If you are not absolutely sure what you are doing, leave this
1438 option alone!
1439
1440 config VMSPLIT_3G
1441 bool "3G/1G user/kernel split"
1442 config VMSPLIT_3G_OPT
1443 depends on !X86_PAE
1444 bool "3G/1G user/kernel split (for full 1G low memory)"
1445 config VMSPLIT_2G
1446 bool "2G/2G user/kernel split"
1447 config VMSPLIT_2G_OPT
1448 depends on !X86_PAE
1449 bool "2G/2G user/kernel split (for full 2G low memory)"
1450 config VMSPLIT_1G
1451 bool "1G/3G user/kernel split"
1452endchoice
1453
1454config PAGE_OFFSET
1455 hex
1456 default 0xB0000000 if VMSPLIT_3G_OPT
1457 default 0x80000000 if VMSPLIT_2G
1458 default 0x78000000 if VMSPLIT_2G_OPT
1459 default 0x40000000 if VMSPLIT_1G
1460 default 0xC0000000
1461 depends on X86_32
1462
1463config HIGHMEM
3c2362e6 1464 def_bool y
506f1d07 1465 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
506f1d07
SR
1466
1467config X86_PAE
9ba16087 1468 bool "PAE (Physical Address Extension) Support"
506f1d07 1469 depends on X86_32 && !HIGHMEM4G
d4a451d5 1470 select PHYS_ADDR_T_64BIT
9d99c712 1471 select SWIOTLB
a7f7f624 1472 help
506f1d07
SR
1473 PAE is required for NX support, and furthermore enables
1474 larger swapspace support for non-overcommit purposes. It
1475 has the cost of more pagetable lookup overhead, and also
1476 consumes more pagetable space per process.
1477
77ef56e4
KS
1478config X86_5LEVEL
1479 bool "Enable 5-level page tables support"
18ec1eaf 1480 default y
eedb92ab 1481 select DYNAMIC_MEMORY_LAYOUT
162434e7 1482 select SPARSEMEM_VMEMMAP
77ef56e4 1483 depends on X86_64
a7f7f624 1484 help
77ef56e4
KS
1485 5-level paging enables access to larger address space:
1486 upto 128 PiB of virtual address space and 4 PiB of
1487 physical address space.
1488
1489 It will be supported by future Intel CPUs.
1490
6657fca0
KS
1491 A kernel with the option enabled can be booted on machines that
1492 support 4- or 5-level paging.
77ef56e4 1493
cb1aaebe 1494 See Documentation/x86/x86_64/5level-paging.rst for more
77ef56e4
KS
1495 information.
1496
1497 Say N if unsure.
1498
10971ab2 1499config X86_DIRECT_GBPAGES
e5008abe 1500 def_bool y
2e1da13f 1501 depends on X86_64
a7f7f624 1502 help
10971ab2
IM
1503 Certain kernel features effectively disable kernel
1504 linear 1 GB mappings (even if the CPU otherwise
1505 supports them), so don't confuse the user by printing
1506 that we have them enabled.
9e899816 1507
5c280cf6
TG
1508config X86_CPA_STATISTICS
1509 bool "Enable statistic for Change Page Attribute"
1510 depends on DEBUG_FS
a7f7f624 1511 help
b75baaf3 1512 Expose statistics about the Change Page Attribute mechanism, which
a943245a 1513 helps to determine the effectiveness of preserving large and huge
5c280cf6
TG
1514 page mappings when mapping protections are changed.
1515
20f07a04
KS
1516config X86_MEM_ENCRYPT
1517 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1518 select DYNAMIC_PHYSICAL_MASK
1519 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1520 def_bool n
1521
7744ccdb
TL
1522config AMD_MEM_ENCRYPT
1523 bool "AMD Secure Memory Encryption (SME) support"
1524 depends on X86_64 && CPU_SUP_AMD
82fef0ad 1525 select DMA_COHERENT_POOL
ce9084ba 1526 select ARCH_USE_MEMREMAP_PROT
597cfe48 1527 select INSTRUCTION_DECODER
aa5a4611 1528 select ARCH_HAS_CC_PLATFORM
20f07a04 1529 select X86_MEM_ENCRYPT
a7f7f624 1530 help
7744ccdb
TL
1531 Say yes to enable support for the encryption of system memory.
1532 This requires an AMD processor that supports Secure Memory
1533 Encryption (SME).
1534
1535config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1536 bool "Activate AMD Secure Memory Encryption (SME) by default"
7744ccdb 1537 depends on AMD_MEM_ENCRYPT
a7f7f624 1538 help
7744ccdb
TL
1539 Say yes to have system memory encrypted by default if running on
1540 an AMD processor that supports Secure Memory Encryption (SME).
1541
1542 If set to Y, then the encryption of system memory can be
1543 deactivated with the mem_encrypt=off command line option.
1544
1545 If set to N, then the encryption of system memory can be
1546 activated with the mem_encrypt=on command line option.
1547
506f1d07
SR
1548# Common NUMA Features
1549config NUMA
e133f6ea 1550 bool "NUMA Memory Allocation and Scheduler Support"
506f1d07 1551 depends on SMP
b5660ba7
PA
1552 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1553 default y if X86_BIGSMP
7ecd19cf 1554 select USE_PERCPU_NUMA_NODE_ID
a7f7f624 1555 help
e133f6ea 1556 Enable NUMA (Non-Uniform Memory Access) support.
fd51b2d7 1557
506f1d07
SR
1558 The kernel will try to allocate memory used by a CPU on the
1559 local memory controller of the CPU and add some more
1560 NUMA awareness to the kernel.
1561
c280ea5e 1562 For 64-bit this is recommended if the system is Intel Core i7
fd51b2d7
KM
1563 (or later), AMD Opteron, or EM64T NUMA.
1564
b5660ba7 1565 For 32-bit this is only needed if you boot a 32-bit
7cf6c945 1566 kernel on a 64-bit NUMA platform.
fd51b2d7
KM
1567
1568 Otherwise, you should say N.
506f1d07 1569
eec1d4fa 1570config AMD_NUMA
3c2362e6
HH
1571 def_bool y
1572 prompt "Old style AMD Opteron NUMA detection"
5da0ef9a 1573 depends on X86_64 && NUMA && PCI
a7f7f624 1574 help
eec1d4fa
HR
1575 Enable AMD NUMA node topology detection. You should say Y here if
1576 you have a multi processor AMD system. This uses an old method to
1577 read the NUMA configuration directly from the builtin Northbridge
1578 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1579 which also takes priority if both are compiled in.
506f1d07
SR
1580
1581config X86_64_ACPI_NUMA
3c2362e6
HH
1582 def_bool y
1583 prompt "ACPI NUMA detection"
506f1d07
SR
1584 depends on X86_64 && NUMA && ACPI && PCI
1585 select ACPI_NUMA
a7f7f624 1586 help
506f1d07
SR
1587 Enable ACPI SRAT based node topology detection.
1588
1589config NUMA_EMU
1590 bool "NUMA emulation"
1b7e03ef 1591 depends on NUMA
a7f7f624 1592 help
506f1d07
SR
1593 Enable NUMA emulation. A flat machine will be split
1594 into virtual nodes when booted with "numa=fake=N", where N is the
1595 number of nodes. This is only useful for debugging.
1596
1597config NODES_SHIFT
d25e26b6 1598 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
51591e31
DR
1599 range 1 10
1600 default "10" if MAXSMP
506f1d07 1601 default "6" if X86_64
506f1d07 1602 default "3"
a9ee6cf5 1603 depends on NUMA
a7f7f624 1604 help
1184dc2f 1605 Specify the maximum number of NUMA Nodes available on the target
692105b8 1606 system. Increases memory reserved to accommodate various tables.
506f1d07 1607
506f1d07
SR
1608config ARCH_FLATMEM_ENABLE
1609 def_bool y
3b16651f 1610 depends on X86_32 && !NUMA
506f1d07 1611
506f1d07
SR
1612config ARCH_SPARSEMEM_ENABLE
1613 def_bool y
6ea30386 1614 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
506f1d07
SR
1615 select SPARSEMEM_STATIC if X86_32
1616 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1617
3b16651f 1618config ARCH_SPARSEMEM_DEFAULT
6ad57f7f 1619 def_bool X86_64 || (NUMA && X86_32)
3b16651f 1620
506f1d07
SR
1621config ARCH_SELECT_MEMORY_MODEL
1622 def_bool y
4eda2bc3 1623 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
506f1d07
SR
1624
1625config ARCH_MEMORY_PROBE
a0842b70 1626 bool "Enable sysfs memory/probe interface"
5c11f00b 1627 depends on MEMORY_HOTPLUG
a0842b70
TK
1628 help
1629 This option enables a sysfs memory/probe interface for testing.
cb1aaebe 1630 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
a0842b70 1631 If you are unsure how to answer this question, answer N.
506f1d07 1632
3b16651f
TH
1633config ARCH_PROC_KCORE_TEXT
1634 def_bool y
1635 depends on X86_64 && PROC_KCORE
1636
a29815a3 1637config ILLEGAL_POINTER_VALUE
b03b016f
KK
1638 hex
1639 default 0 if X86_32
1640 default 0xdead000000000000 if X86_64
a29815a3 1641
7a67832c
DW
1642config X86_PMEM_LEGACY_DEVICE
1643 bool
1644
ec776ef6 1645config X86_PMEM_LEGACY
7a67832c 1646 tristate "Support non-standard NVDIMMs and ADR protected memory"
9f53f9fa
DW
1647 depends on PHYS_ADDR_T_64BIT
1648 depends on BLK_DEV
7a67832c 1649 select X86_PMEM_LEGACY_DEVICE
7b27a862 1650 select NUMA_KEEP_MEMINFO if NUMA
9f53f9fa 1651 select LIBNVDIMM
ec776ef6
CH
1652 help
1653 Treat memory marked using the non-standard e820 type of 12 as used
1654 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1655 The kernel will offer these regions to the 'pmem' driver so
1656 they can be used for persistent storage.
1657
1658 Say Y if unsure.
1659
506f1d07
SR
1660config HIGHPTE
1661 bool "Allocate 3rd-level pagetables from highmem"
6fc108a0 1662 depends on HIGHMEM
a7f7f624 1663 help
506f1d07
SR
1664 The VM uses one page table entry for each page of physical memory.
1665 For systems with a lot of RAM, this can be wasteful of precious
1666 low memory. Setting this option will put user-space page table
1667 entries in high memory.
1668
9f077871 1669config X86_CHECK_BIOS_CORRUPTION
8f9ca475 1670 bool "Check for low memory corruption"
a7f7f624 1671 help
8f9ca475
IM
1672 Periodically check for memory corruption in low memory, which
1673 is suspected to be caused by BIOS. Even when enabled in the
1674 configuration, it is disabled at runtime. Enable it by
1675 setting "memory_corruption_check=1" on the kernel command
1676 line. By default it scans the low 64k of memory every 60
1677 seconds; see the memory_corruption_check_size and
1678 memory_corruption_check_period parameters in
8c27ceff 1679 Documentation/admin-guide/kernel-parameters.rst to adjust this.
8f9ca475
IM
1680
1681 When enabled with the default parameters, this option has
1682 almost no overhead, as it reserves a relatively small amount
1683 of memory and scans it infrequently. It both detects corruption
1684 and prevents it from affecting the running system.
1685
1686 It is, however, intended as a diagnostic tool; if repeatable
1687 BIOS-originated corruption always affects the same memory,
1688 you can use memmap= to prevent the kernel from using that
1689 memory.
9f077871 1690
c885df50 1691config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
8f9ca475 1692 bool "Set the default setting of memory_corruption_check"
c885df50
JF
1693 depends on X86_CHECK_BIOS_CORRUPTION
1694 default y
a7f7f624 1695 help
8f9ca475
IM
1696 Set whether the default state of memory_corruption_check is
1697 on or off.
c885df50 1698
506f1d07
SR
1699config MATH_EMULATION
1700 bool
a5b9e5a2 1701 depends on MODIFY_LDT_SYSCALL
87d6021b 1702 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
a7f7f624 1703 help
506f1d07
SR
1704 Linux can emulate a math coprocessor (used for floating point
1705 operations) if you don't have one. 486DX and Pentium processors have
1706 a math coprocessor built in, 486SX and 386 do not, unless you added
1707 a 487DX or 387, respectively. (The messages during boot time can
1708 give you some hints here ["man dmesg"].) Everyone needs either a
1709 coprocessor or this emulation.
1710
1711 If you don't have a math coprocessor, you need to say Y here; if you
1712 say Y here even though you have a coprocessor, the coprocessor will
1713 be used nevertheless. (This behavior can be changed with the kernel
1714 command line option "no387", which comes handy if your coprocessor
1715 is broken. Try "man bootparam" or see the documentation of your boot
1716 loader (lilo or loadlin) about how to pass options to the kernel at
1717 boot time.) This means that it is a good idea to say Y here if you
1718 intend to use this kernel on different machines.
1719
1720 More information about the internals of the Linux math coprocessor
1721 emulation can be found in <file:arch/x86/math-emu/README>.
1722
1723 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1724 kernel, it won't hurt.
1725
1726config MTRR
6fc108a0 1727 def_bool y
6a108a14 1728 prompt "MTRR (Memory Type Range Register) support" if EXPERT
a7f7f624 1729 help
506f1d07
SR
1730 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1731 the Memory Type Range Registers (MTRRs) may be used to control
1732 processor access to memory ranges. This is most useful if you have
1733 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1734 allows bus write transfers to be combined into a larger transfer
1735 before bursting over the PCI/AGP bus. This can increase performance
1736 of image write operations 2.5 times or more. Saying Y here creates a
1737 /proc/mtrr file which may be used to manipulate your processor's
1738 MTRRs. Typically the X server should use this.
1739
1740 This code has a reasonably generic interface so that similar
1741 control registers on other processors can be easily supported
1742 as well:
1743
1744 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1745 Registers (ARRs) which provide a similar functionality to MTRRs. For
1746 these, the ARRs are used to emulate the MTRRs.
1747 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1748 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1749 write-combining. All of these processors are supported by this code
1750 and it makes sense to say Y here if you have one of them.
1751
1752 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1753 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1754 can lead to all sorts of problems, so it's good to say Y here.
1755
1756 You can safely say Y even if your machine doesn't have MTRRs, you'll
1757 just add about 9 KB to your kernel.
1758
cb1aaebe 1759 See <file:Documentation/x86/mtrr.rst> for more information.
506f1d07 1760
95ffa243 1761config MTRR_SANITIZER
2ffb3501 1762 def_bool y
95ffa243
YL
1763 prompt "MTRR cleanup support"
1764 depends on MTRR
a7f7f624 1765 help
aba3728c
TG
1766 Convert MTRR layout from continuous to discrete, so X drivers can
1767 add writeback entries.
95ffa243 1768
aba3728c 1769 Can be disabled with disable_mtrr_cleanup on the kernel command line.
692105b8 1770 The largest mtrr entry size for a continuous block can be set with
aba3728c 1771 mtrr_chunk_size.
95ffa243 1772
2ffb3501 1773 If unsure, say Y.
95ffa243
YL
1774
1775config MTRR_SANITIZER_ENABLE_DEFAULT
f5098d62
YL
1776 int "MTRR cleanup enable value (0-1)"
1777 range 0 1
1778 default "0"
95ffa243 1779 depends on MTRR_SANITIZER
a7f7f624 1780 help
f5098d62 1781 Enable mtrr cleanup default value
95ffa243 1782
12031a62
YL
1783config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1784 int "MTRR cleanup spare reg num (0-7)"
1785 range 0 7
1786 default "1"
1787 depends on MTRR_SANITIZER
a7f7f624 1788 help
12031a62 1789 mtrr cleanup spare entries default, it can be changed via
aba3728c 1790 mtrr_spare_reg_nr=N on the kernel command line.
12031a62 1791
2e5d9c85 1792config X86_PAT
6fc108a0 1793 def_bool y
6a108a14 1794 prompt "x86 PAT support" if EXPERT
2a8a2719 1795 depends on MTRR
a7f7f624 1796 help
2e5d9c85 1797 Use PAT attributes to setup page level cache control.
042b78e4 1798
2e5d9c85 1799 PATs are the modern equivalents of MTRRs and are much more
1800 flexible than MTRRs.
1801
1802 Say N here if you see bootup problems (boot crash, boot hang,
042b78e4 1803 spontaneous reboots) or a non-working video driver.
2e5d9c85 1804
1805 If unsure, say Y.
1806
46cf98cd
VP
1807config ARCH_USES_PG_UNCACHED
1808 def_bool y
1809 depends on X86_PAT
1810
628c6246
PA
1811config ARCH_RANDOM
1812 def_bool y
1813 prompt "x86 architectural random number generator" if EXPERT
a7f7f624 1814 help
628c6246
PA
1815 Enable the x86 architectural RDRAND instruction
1816 (Intel Bull Mountain technology) to generate random numbers.
1817 If supported, this is a high bandwidth, cryptographically
1818 secure hardware random number generator.
1819
51ae4a2d
PA
1820config X86_SMAP
1821 def_bool y
1822 prompt "Supervisor Mode Access Prevention" if EXPERT
a7f7f624 1823 help
51ae4a2d
PA
1824 Supervisor Mode Access Prevention (SMAP) is a security
1825 feature in newer Intel processors. There is a small
1826 performance cost if this enabled and turned on; there is
1827 also a small increase in the kernel size if this is enabled.
1828
1829 If unsure, say Y.
1830
b971880f 1831config X86_UMIP
796ebc81 1832 def_bool y
b971880f 1833 prompt "User Mode Instruction Prevention" if EXPERT
a7f7f624 1834 help
b971880f
BM
1835 User Mode Instruction Prevention (UMIP) is a security feature in
1836 some x86 processors. If enabled, a general protection fault is
1837 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1838 executed in user mode. These instructions unnecessarily expose
1839 information about the hardware state.
796ebc81
RN
1840
1841 The vast majority of applications do not use these instructions.
1842 For the very few that do, software emulation is provided in
1843 specific cases in protected and virtual-8086 modes. Emulated
1844 results are dummy.
aa35f896 1845
156ff4a5
PZ
1846config CC_HAS_IBT
1847 # GCC >= 9 and binutils >= 2.29
1848 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1849 # Clang/LLVM >= 14
262448f3
NC
1850 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
1851 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
156ff4a5 1852 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
262448f3 1853 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
156ff4a5
PZ
1854 $(as-instr,endbr64)
1855
1856config X86_KERNEL_IBT
1857 prompt "Indirect Branch Tracking"
1858 bool
ed53a0d9 1859 depends on X86_64 && CC_HAS_IBT && STACK_VALIDATION
f6a2c2b2
NC
1860 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
1861 depends on !LD_IS_LLD || LLD_VERSION >= 140000
156ff4a5
PZ
1862 help
1863 Build the kernel with support for Indirect Branch Tracking, a
1864 hardware support course-grain forward-edge Control Flow Integrity
1865 protection. It enforces that all indirect calls must land on
1866 an ENDBR instruction, as such, the compiler will instrument the
1867 code with them to make this happen.
1868
ed53a0d9
PZ
1869 In addition to building the kernel with IBT, seal all functions that
1870 are not indirect call targets, avoiding them ever becomming one.
1871
1872 This requires LTO like objtool runs and will slow down the build. It
1873 does significantly reduce the number of ENDBR instructions in the
1874 kernel image.
1875
35e97790 1876config X86_INTEL_MEMORY_PROTECTION_KEYS
38f3e775 1877 prompt "Memory Protection Keys"
35e97790 1878 def_bool y
284244a9 1879 # Note: only available in 64-bit mode
38f3e775 1880 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
52c8e601
IM
1881 select ARCH_USES_HIGH_VMA_FLAGS
1882 select ARCH_HAS_PKEYS
a7f7f624 1883 help
284244a9
DH
1884 Memory Protection Keys provides a mechanism for enforcing
1885 page-based protections, but without requiring modification of the
1886 page tables when an application changes protection domains.
1887
1eecbcdc 1888 For details, see Documentation/core-api/protection-keys.rst
284244a9
DH
1889
1890 If unsure, say y.
35e97790 1891
db616173
MH
1892choice
1893 prompt "TSX enable mode"
1894 depends on CPU_SUP_INTEL
1895 default X86_INTEL_TSX_MODE_OFF
1896 help
1897 Intel's TSX (Transactional Synchronization Extensions) feature
1898 allows to optimize locking protocols through lock elision which
1899 can lead to a noticeable performance boost.
1900
1901 On the other hand it has been shown that TSX can be exploited
1902 to form side channel attacks (e.g. TAA) and chances are there
1903 will be more of those attacks discovered in the future.
1904
1905 Therefore TSX is not enabled by default (aka tsx=off). An admin
1906 might override this decision by tsx=on the command line parameter.
1907 Even with TSX enabled, the kernel will attempt to enable the best
1908 possible TAA mitigation setting depending on the microcode available
1909 for the particular machine.
1910
1911 This option allows to set the default tsx mode between tsx=on, =off
1912 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1913 details.
1914
1915 Say off if not sure, auto if TSX is in use but it should be used on safe
1916 platforms or on if TSX is in use and the security aspect of tsx is not
1917 relevant.
1918
1919config X86_INTEL_TSX_MODE_OFF
1920 bool "off"
1921 help
1922 TSX is disabled if possible - equals to tsx=off command line parameter.
1923
1924config X86_INTEL_TSX_MODE_ON
1925 bool "on"
1926 help
1927 TSX is always enabled on TSX capable HW - equals the tsx=on command
1928 line parameter.
1929
1930config X86_INTEL_TSX_MODE_AUTO
1931 bool "auto"
1932 help
1933 TSX is enabled on TSX capable HW that is believed to be safe against
1934 side channel attacks- equals the tsx=auto command line parameter.
1935endchoice
1936
e7e05452
SC
1937config X86_SGX
1938 bool "Software Guard eXtensions (SGX)"
1939 depends on X86_64 && CPU_SUP_INTEL
1940 depends on CRYPTO=y
1941 depends on CRYPTO_SHA256=y
1942 select SRCU
1943 select MMU_NOTIFIER
901ddbb9 1944 select NUMA_KEEP_MEMINFO if NUMA
40e0e784 1945 select XARRAY_MULTI
e7e05452
SC
1946 help
1947 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1948 that can be used by applications to set aside private regions of code
1949 and data, referred to as enclaves. An enclave's private memory can
1950 only be accessed by code running within the enclave. Accesses from
1951 outside the enclave, including other enclaves, are disallowed by
1952 hardware.
1953
1954 If unsure, say N.
1955
506f1d07 1956config EFI
9ba16087 1957 bool "EFI runtime service support"
5b83683f 1958 depends on ACPI
f6ce5002 1959 select UCS2_STRING
022ee6c5 1960 select EFI_RUNTIME_WRAPPERS
1ff2fc02 1961 select ARCH_USE_MEMREMAP_PROT
a7f7f624 1962 help
8f9ca475
IM
1963 This enables the kernel to use EFI runtime services that are
1964 available (such as the EFI variable services).
506f1d07 1965
8f9ca475
IM
1966 This option is only useful on systems that have EFI firmware.
1967 In addition, you should use the latest ELILO loader available
1968 at <http://elilo.sourceforge.net> in order to take advantage
1969 of EFI runtime services. However, even with this option, the
1970 resultant kernel should continue to boot on existing non-EFI
1971 platforms.
506f1d07 1972
291f3632 1973config EFI_STUB
8f24f8c2 1974 bool "EFI stub support"
c6dbd3e5 1975 depends on EFI
8f24f8c2
AB
1976 depends on $(cc-option,-mabi=ms) || X86_32
1977 select RELOCATABLE
a7f7f624 1978 help
8f24f8c2 1979 This kernel feature allows a bzImage to be loaded directly
291f3632
MF
1980 by EFI firmware without the use of a bootloader.
1981
4f4cfa6c 1982 See Documentation/admin-guide/efi-stub.rst for more information.
0c759662 1983
7d453eee
MF
1984config EFI_MIXED
1985 bool "EFI mixed-mode support"
1986 depends on EFI_STUB && X86_64
a7f7f624 1987 help
7d453eee
MF
1988 Enabling this feature allows a 64-bit kernel to be booted
1989 on a 32-bit firmware, provided that your CPU supports 64-bit
1990 mode.
1991
1992 Note that it is not possible to boot a mixed-mode enabled
1993 kernel via the EFI boot stub - a bootloader that supports
1994 the EFI handover protocol must be used.
1995
1996 If unsure, say N.
1997
8636a1f9 1998source "kernel/Kconfig.hz"
506f1d07
SR
1999
2000config KEXEC
2001 bool "kexec system call"
2965faa5 2002 select KEXEC_CORE
a7f7f624 2003 help
506f1d07
SR
2004 kexec is a system call that implements the ability to shutdown your
2005 current kernel, and to start another kernel. It is like a reboot
2006 but it is independent of the system firmware. And like a reboot
2007 you can start any kernel with it, not just Linux.
2008
2009 The name comes from the similarity to the exec system call.
2010
2011 It is an ongoing process to be certain the hardware in a machine
2012 is properly shutdown, so do not be surprised if this code does not
bf220695
GU
2013 initially work for you. As of this writing the exact hardware
2014 interface is strongly in flux, so no good recommendation can be
2015 made.
506f1d07 2016
74ca317c
VG
2017config KEXEC_FILE
2018 bool "kexec file based system call"
2965faa5 2019 select KEXEC_CORE
74ca317c 2020 select BUILD_BIN2C
74ca317c
VG
2021 depends on X86_64
2022 depends on CRYPTO=y
2023 depends on CRYPTO_SHA256=y
a7f7f624 2024 help
74ca317c
VG
2025 This is new version of kexec system call. This system call is
2026 file based and takes file descriptors as system call argument
2027 for kernel and initramfs as opposed to list of segments as
2028 accepted by previous system call.
2029
b799a09f
AT
2030config ARCH_HAS_KEXEC_PURGATORY
2031 def_bool KEXEC_FILE
2032
99d5cadf 2033config KEXEC_SIG
8e7d8381 2034 bool "Verify kernel signature during kexec_file_load() syscall"
74ca317c 2035 depends on KEXEC_FILE
a7f7f624 2036 help
d8eb8940 2037
99d5cadf
JB
2038 This option makes the kexec_file_load() syscall check for a valid
2039 signature of the kernel image. The image can still be loaded without
2040 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2041 there's a signature that we can check, then it must be valid.
2042
2043 In addition to this option, you need to enable signature
d8eb8940
BP
2044 verification for the corresponding kernel image type being
2045 loaded in order for this to work.
8e7d8381 2046
99d5cadf
JB
2047config KEXEC_SIG_FORCE
2048 bool "Require a valid signature in kexec_file_load() syscall"
2049 depends on KEXEC_SIG
a7f7f624 2050 help
99d5cadf
JB
2051 This option makes kernel signature verification mandatory for
2052 the kexec_file_load() syscall.
2053
8e7d8381
VG
2054config KEXEC_BZIMAGE_VERIFY_SIG
2055 bool "Enable bzImage signature verification support"
99d5cadf 2056 depends on KEXEC_SIG
8e7d8381
VG
2057 depends on SIGNED_PE_FILE_VERIFICATION
2058 select SYSTEM_TRUSTED_KEYRING
a7f7f624 2059 help
8e7d8381
VG
2060 Enable bzImage signature verification support.
2061
506f1d07 2062config CRASH_DUMP
04b69447 2063 bool "kernel crash dumps"
506f1d07 2064 depends on X86_64 || (X86_32 && HIGHMEM)
a7f7f624 2065 help
506f1d07
SR
2066 Generate crash dump after being started by kexec.
2067 This should be normally only set in special crash dump kernels
2068 which are loaded in the main kernel with kexec-tools into
2069 a specially reserved region and then later executed after
2070 a crash by kdump/kexec. The crash dump kernel must be compiled
2071 to a memory address not used by the main kernel or BIOS using
2072 PHYSICAL_START, or it must be built as a relocatable image
2073 (CONFIG_RELOCATABLE=y).
330d4810 2074 For more details see Documentation/admin-guide/kdump/kdump.rst
506f1d07 2075
3ab83521 2076config KEXEC_JUMP
6ea30386 2077 bool "kexec jump"
fee7b0d8 2078 depends on KEXEC && HIBERNATION
a7f7f624 2079 help
89081d17
HY
2080 Jump between original kernel and kexeced kernel and invoke
2081 code in physical address mode via KEXEC
3ab83521 2082
506f1d07 2083config PHYSICAL_START
6a108a14 2084 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
ceefccc9 2085 default "0x1000000"
a7f7f624 2086 help
506f1d07
SR
2087 This gives the physical address where the kernel is loaded.
2088
2089 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2090 bzImage will decompress itself to above physical address and
2091 run from there. Otherwise, bzImage will run from the address where
2092 it has been loaded by the boot loader and will ignore above physical
2093 address.
2094
2095 In normal kdump cases one does not have to set/change this option
2096 as now bzImage can be compiled as a completely relocatable image
2097 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2098 address. This option is mainly useful for the folks who don't want
2099 to use a bzImage for capturing the crash dump and want to use a
2100 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2101 to be specifically compiled to run from a specific memory area
2102 (normally a reserved region) and this option comes handy.
2103
ceefccc9
PA
2104 So if you are using bzImage for capturing the crash dump,
2105 leave the value here unchanged to 0x1000000 and set
2106 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2107 for capturing the crash dump change this value to start of
2108 the reserved region. In other words, it can be set based on
2109 the "X" value as specified in the "crashkernel=YM@XM"
2110 command line boot parameter passed to the panic-ed
330d4810 2111 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
ceefccc9 2112 for more details about crash dumps.
506f1d07
SR
2113
2114 Usage of bzImage for capturing the crash dump is recommended as
2115 one does not have to build two kernels. Same kernel can be used
2116 as production kernel and capture kernel. Above option should have
2117 gone away after relocatable bzImage support is introduced. But it
2118 is present because there are users out there who continue to use
2119 vmlinux for dump capture. This option should go away down the
2120 line.
2121
2122 Don't change this unless you know what you are doing.
2123
2124config RELOCATABLE
26717808
PA
2125 bool "Build a relocatable kernel"
2126 default y
a7f7f624 2127 help
506f1d07
SR
2128 This builds a kernel image that retains relocation information
2129 so it can be loaded someplace besides the default 1MB.
2130 The relocations tend to make the kernel binary about 10% larger,
2131 but are discarded at runtime.
2132
2133 One use is for the kexec on panic case where the recovery kernel
2134 must live at a different physical address than the primary
2135 kernel.
2136
2137 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2138 it has been loaded at and the compile time physical address
8ab3820f 2139 (CONFIG_PHYSICAL_START) is used as the minimum location.
506f1d07 2140
8ab3820f 2141config RANDOMIZE_BASE
e8581e3d 2142 bool "Randomize the address of the kernel image (KASLR)"
8ab3820f 2143 depends on RELOCATABLE
6807c846 2144 default y
a7f7f624 2145 help
e8581e3d
BH
2146 In support of Kernel Address Space Layout Randomization (KASLR),
2147 this randomizes the physical address at which the kernel image
2148 is decompressed and the virtual address where the kernel
2149 image is mapped, as a security feature that deters exploit
2150 attempts relying on knowledge of the location of kernel
2151 code internals.
2152
ed9f007e
KC
2153 On 64-bit, the kernel physical and virtual addresses are
2154 randomized separately. The physical address will be anywhere
2155 between 16MB and the top of physical memory (up to 64TB). The
2156 virtual address will be randomized from 16MB up to 1GB (9 bits
2157 of entropy). Note that this also reduces the memory space
2158 available to kernel modules from 1.5GB to 1GB.
2159
2160 On 32-bit, the kernel physical and virtual addresses are
2161 randomized together. They will be randomized from 16MB up to
2162 512MB (8 bits of entropy).
e8581e3d
BH
2163
2164 Entropy is generated using the RDRAND instruction if it is
2165 supported. If RDTSC is supported, its value is mixed into
2166 the entropy pool as well. If neither RDRAND nor RDTSC are
ed9f007e
KC
2167 supported, then entropy is read from the i8254 timer. The
2168 usable entropy is limited by the kernel being built using
2169 2GB addressing, and that PHYSICAL_ALIGN must be at a
2170 minimum of 2MB. As a result, only 10 bits of entropy are
2171 theoretically possible, but the implementations are further
2172 limited due to memory layouts.
e8581e3d 2173
6807c846 2174 If unsure, say Y.
8ab3820f
KC
2175
2176# Relocation on x86 needs some additional build support
845adf72
PA
2177config X86_NEED_RELOCS
2178 def_bool y
8ab3820f 2179 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
845adf72 2180
506f1d07 2181config PHYSICAL_ALIGN
a0215061 2182 hex "Alignment value to which kernel should be aligned"
8ab3820f 2183 default "0x200000"
a0215061
KC
2184 range 0x2000 0x1000000 if X86_32
2185 range 0x200000 0x1000000 if X86_64
a7f7f624 2186 help
506f1d07
SR
2187 This value puts the alignment restrictions on physical address
2188 where kernel is loaded and run from. Kernel is compiled for an
2189 address which meets above alignment restriction.
2190
2191 If bootloader loads the kernel at a non-aligned address and
2192 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2193 address aligned to above value and run from there.
2194
2195 If bootloader loads the kernel at a non-aligned address and
2196 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2197 load address and decompress itself to the address it has been
2198 compiled for and run from there. The address for which kernel is
2199 compiled already meets above alignment restrictions. Hence the
2200 end result is that kernel runs from a physical address meeting
2201 above alignment restrictions.
2202
a0215061
KC
2203 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2204 this value must be a multiple of 0x200000.
2205
506f1d07
SR
2206 Don't change this unless you know what you are doing.
2207
eedb92ab
KS
2208config DYNAMIC_MEMORY_LAYOUT
2209 bool
a7f7f624 2210 help
eedb92ab
KS
2211 This option makes base addresses of vmalloc and vmemmap as well as
2212 __PAGE_OFFSET movable during boot.
2213
0483e1fa
TG
2214config RANDOMIZE_MEMORY
2215 bool "Randomize the kernel memory sections"
2216 depends on X86_64
2217 depends on RANDOMIZE_BASE
eedb92ab 2218 select DYNAMIC_MEMORY_LAYOUT
0483e1fa 2219 default RANDOMIZE_BASE
a7f7f624 2220 help
0483e1fa
TG
2221 Randomizes the base virtual address of kernel memory sections
2222 (physical memory mapping, vmalloc & vmemmap). This security feature
2223 makes exploits relying on predictable memory locations less reliable.
2224
2225 The order of allocations remains unchanged. Entropy is generated in
2226 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2227 configuration have in average 30,000 different possible virtual
2228 addresses for each memory section.
2229
6807c846 2230 If unsure, say Y.
0483e1fa 2231
90397a41
TG
2232config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2233 hex "Physical memory mapping padding" if EXPERT
2234 depends on RANDOMIZE_MEMORY
2235 default "0xa" if MEMORY_HOTPLUG
2236 default "0x0"
2237 range 0x1 0x40 if MEMORY_HOTPLUG
2238 range 0x0 0x40
a7f7f624 2239 help
90397a41
TG
2240 Define the padding in terabytes added to the existing physical
2241 memory size during kernel memory randomization. It is useful
2242 for memory hotplug support but reduces the entropy available for
2243 address randomization.
2244
2245 If unsure, leave at the default value.
2246
506f1d07 2247config HOTPLUG_CPU
bebd024e 2248 def_bool y
40b31360 2249 depends on SMP
506f1d07 2250
80aa1dff
FY
2251config BOOTPARAM_HOTPLUG_CPU0
2252 bool "Set default setting of cpu0_hotpluggable"
2c922cd0 2253 depends on HOTPLUG_CPU
a7f7f624 2254 help
80aa1dff
FY
2255 Set whether default state of cpu0_hotpluggable is on or off.
2256
2257 Say Y here to enable CPU0 hotplug by default. If this switch
2258 is turned on, there is no need to give cpu0_hotplug kernel
2259 parameter and the CPU0 hotplug feature is enabled by default.
2260
2261 Please note: there are two known CPU0 dependencies if you want
2262 to enable the CPU0 hotplug feature either by this switch or by
2263 cpu0_hotplug kernel parameter.
2264
2265 First, resume from hibernate or suspend always starts from CPU0.
2266 So hibernate and suspend are prevented if CPU0 is offline.
2267
2268 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2269 offline if any interrupt can not migrate out of CPU0. There may
2270 be other CPU0 dependencies.
2271
2272 Please make sure the dependencies are under your control before
2273 you enable this feature.
2274
2275 Say N if you don't want to enable CPU0 hotplug feature by default.
2276 You still can enable the CPU0 hotplug feature at boot by kernel
2277 parameter cpu0_hotplug.
2278
a71c8bc5
FY
2279config DEBUG_HOTPLUG_CPU0
2280 def_bool n
2281 prompt "Debug CPU0 hotplug"
2c922cd0 2282 depends on HOTPLUG_CPU
a7f7f624 2283 help
a71c8bc5
FY
2284 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2285 soon as possible and boots up userspace with CPU0 offlined. User
2286 can online CPU0 back after boot time.
2287
2288 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2289 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2290 compilation or giving cpu0_hotplug kernel parameter at boot.
2291
2292 If unsure, say N.
2293
506f1d07 2294config COMPAT_VDSO
b0b49f26
AL
2295 def_bool n
2296 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
953fee1d 2297 depends on COMPAT_32
a7f7f624 2298 help
b0b49f26
AL
2299 Certain buggy versions of glibc will crash if they are
2300 presented with a 32-bit vDSO that is not mapped at the address
2301 indicated in its segment table.
e84446de 2302
b0b49f26
AL
2303 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2304 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2305 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2306 the only released version with the bug, but OpenSUSE 9
2307 contains a buggy "glibc 2.3.2".
506f1d07 2308
b0b49f26
AL
2309 The symptom of the bug is that everything crashes on startup, saying:
2310 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2311
2312 Saying Y here changes the default value of the vdso32 boot
2313 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2314 This works around the glibc bug but hurts performance.
2315
2316 If unsure, say N: if you are compiling your own kernel, you
2317 are unlikely to be using a buggy version of glibc.
506f1d07 2318
3dc33bd3
KC
2319choice
2320 prompt "vsyscall table for legacy applications"
2321 depends on X86_64
625b7b7f 2322 default LEGACY_VSYSCALL_XONLY
3dc33bd3
KC
2323 help
2324 Legacy user code that does not know how to find the vDSO expects
2325 to be able to issue three syscalls by calling fixed addresses in
2326 kernel space. Since this location is not randomized with ASLR,
2327 it can be used to assist security vulnerability exploitation.
2328
2329 This setting can be changed at boot time via the kernel command
bd49e16e 2330 line parameter vsyscall=[emulate|xonly|none].
3dc33bd3
KC
2331
2332 On a system with recent enough glibc (2.14 or newer) and no
2333 static binaries, you can say None without a performance penalty
2334 to improve security.
2335
bd49e16e 2336 If unsure, select "Emulate execution only".
3dc33bd3 2337
3dc33bd3 2338 config LEGACY_VSYSCALL_EMULATE
bd49e16e 2339 bool "Full emulation"
3dc33bd3 2340 help
bd49e16e
AL
2341 The kernel traps and emulates calls into the fixed vsyscall
2342 address mapping. This makes the mapping non-executable, but
2343 it still contains readable known contents, which could be
2344 used in certain rare security vulnerability exploits. This
2345 configuration is recommended when using legacy userspace
2346 that still uses vsyscalls along with legacy binary
2347 instrumentation tools that require code to be readable.
2348
2349 An example of this type of legacy userspace is running
2350 Pin on an old binary that still uses vsyscalls.
2351
2352 config LEGACY_VSYSCALL_XONLY
2353 bool "Emulate execution only"
2354 help
2355 The kernel traps and emulates calls into the fixed vsyscall
2356 address mapping and does not allow reads. This
2357 configuration is recommended when userspace might use the
2358 legacy vsyscall area but support for legacy binary
2359 instrumentation of legacy code is not needed. It mitigates
2360 certain uses of the vsyscall area as an ASLR-bypassing
2361 buffer.
3dc33bd3
KC
2362
2363 config LEGACY_VSYSCALL_NONE
2364 bool "None"
2365 help
2366 There will be no vsyscall mapping at all. This will
2367 eliminate any risk of ASLR bypass due to the vsyscall
2368 fixed address mapping. Attempts to use the vsyscalls
2369 will be reported to dmesg, so that either old or
2370 malicious userspace programs can be identified.
2371
2372endchoice
2373
516cbf37
TB
2374config CMDLINE_BOOL
2375 bool "Built-in kernel command line"
a7f7f624 2376 help
516cbf37
TB
2377 Allow for specifying boot arguments to the kernel at
2378 build time. On some systems (e.g. embedded ones), it is
2379 necessary or convenient to provide some or all of the
2380 kernel boot arguments with the kernel itself (that is,
2381 to not rely on the boot loader to provide them.)
2382
2383 To compile command line arguments into the kernel,
2384 set this option to 'Y', then fill in the
69711ca1 2385 boot arguments in CONFIG_CMDLINE.
516cbf37
TB
2386
2387 Systems with fully functional boot loaders (i.e. non-embedded)
2388 should leave this option set to 'N'.
2389
2390config CMDLINE
2391 string "Built-in kernel command string"
2392 depends on CMDLINE_BOOL
2393 default ""
a7f7f624 2394 help
516cbf37
TB
2395 Enter arguments here that should be compiled into the kernel
2396 image and used at boot time. If the boot loader provides a
2397 command line at boot time, it is appended to this string to
2398 form the full kernel command line, when the system boots.
2399
2400 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2401 change this behavior.
2402
2403 In most cases, the command line (whether built-in or provided
2404 by the boot loader) should specify the device for the root
2405 file system.
2406
2407config CMDLINE_OVERRIDE
2408 bool "Built-in command line overrides boot loader arguments"
645e6466 2409 depends on CMDLINE_BOOL && CMDLINE != ""
a7f7f624 2410 help
516cbf37
TB
2411 Set this option to 'Y' to have the kernel ignore the boot loader
2412 command line, and use ONLY the built-in command line.
2413
2414 This is used to work around broken boot loaders. This should
2415 be set to 'N' under normal conditions.
2416
a5b9e5a2
AL
2417config MODIFY_LDT_SYSCALL
2418 bool "Enable the LDT (local descriptor table)" if EXPERT
2419 default y
a7f7f624 2420 help
a5b9e5a2
AL
2421 Linux can allow user programs to install a per-process x86
2422 Local Descriptor Table (LDT) using the modify_ldt(2) system
2423 call. This is required to run 16-bit or segmented code such as
2424 DOSEMU or some Wine programs. It is also used by some very old
2425 threading libraries.
2426
2427 Enabling this feature adds a small amount of overhead to
2428 context switches and increases the low-level kernel attack
2429 surface. Disabling it removes the modify_ldt(2) system call.
2430
2431 Saying 'N' here may make sense for embedded or server kernels.
2432
3aac3ebe
TG
2433config STRICT_SIGALTSTACK_SIZE
2434 bool "Enforce strict size checking for sigaltstack"
2435 depends on DYNAMIC_SIGFRAME
2436 help
2437 For historical reasons MINSIGSTKSZ is a constant which became
2438 already too small with AVX512 support. Add a mechanism to
2439 enforce strict checking of the sigaltstack size against the
2440 real size of the FPU frame. This option enables the check
2441 by default. It can also be controlled via the kernel command
2442 line option 'strict_sas_size' independent of this config
2443 switch. Enabling it might break existing applications which
2444 allocate a too small sigaltstack but 'work' because they
2445 never get a signal delivered.
2446
2447 Say 'N' unless you want to really enforce this check.
2448
b700e7f0
SJ
2449source "kernel/livepatch/Kconfig"
2450
506f1d07
SR
2451endmenu
2452
3072e413
MH
2453config ARCH_HAS_ADD_PAGES
2454 def_bool y
5c11f00b 2455 depends on ARCH_ENABLE_MEMORY_HOTPLUG
3072e413 2456
f91ef222
OS
2457config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2458 def_bool y
2459
da85f865 2460menu "Power management and ACPI options"
e279b6c1
SR
2461
2462config ARCH_HIBERNATION_HEADER
3c2362e6 2463 def_bool y
44556530 2464 depends on HIBERNATION
e279b6c1
SR
2465
2466source "kernel/power/Kconfig"
2467
2468source "drivers/acpi/Kconfig"
2469
a6b68076 2470config X86_APM_BOOT
6fc108a0 2471 def_bool y
282e5aab 2472 depends on APM
a6b68076 2473
e279b6c1
SR
2474menuconfig APM
2475 tristate "APM (Advanced Power Management) BIOS support"
efefa6f6 2476 depends on X86_32 && PM_SLEEP
a7f7f624 2477 help
e279b6c1
SR
2478 APM is a BIOS specification for saving power using several different
2479 techniques. This is mostly useful for battery powered laptops with
2480 APM compliant BIOSes. If you say Y here, the system time will be
2481 reset after a RESUME operation, the /proc/apm device will provide
2482 battery status information, and user-space programs will receive
2483 notification of APM "events" (e.g. battery status change).
2484
2485 If you select "Y" here, you can disable actual use of the APM
2486 BIOS by passing the "apm=off" option to the kernel at boot time.
2487
2488 Note that the APM support is almost completely disabled for
2489 machines with more than one CPU.
2490
2491 In order to use APM, you will need supporting software. For location
151f4e2b 2492 and more information, read <file:Documentation/power/apm-acpi.rst>
2dc98fd3 2493 and the Battery Powered Linux mini-HOWTO, available from
e279b6c1
SR
2494 <http://www.tldp.org/docs.html#howto>.
2495
2496 This driver does not spin down disk drives (see the hdparm(8)
2497 manpage ("man 8 hdparm") for that), and it doesn't turn off
2498 VESA-compliant "green" monitors.
2499
2500 This driver does not support the TI 4000M TravelMate and the ACER
2501 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2502 desktop machines also don't have compliant BIOSes, and this driver
2503 may cause those machines to panic during the boot phase.
2504
2505 Generally, if you don't have a battery in your machine, there isn't
2506 much point in using this driver and you should say N. If you get
2507 random kernel OOPSes or reboots that don't seem to be related to
2508 anything, try disabling/enabling this option (or disabling/enabling
2509 APM in your BIOS).
2510
2511 Some other things you should try when experiencing seemingly random,
2512 "weird" problems:
2513
2514 1) make sure that you have enough swap space and that it is
2515 enabled.
2516 2) pass the "no-hlt" option to the kernel
2517 3) switch on floating point emulation in the kernel and pass
2518 the "no387" option to the kernel
2519 4) pass the "floppy=nodma" option to the kernel
2520 5) pass the "mem=4M" option to the kernel (thereby disabling
2521 all but the first 4 MB of RAM)
2522 6) make sure that the CPU is not over clocked.
2523 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2524 8) disable the cache from your BIOS settings
2525 9) install a fan for the video card or exchange video RAM
2526 10) install a better fan for the CPU
2527 11) exchange RAM chips
2528 12) exchange the motherboard.
2529
2530 To compile this driver as a module, choose M here: the
2531 module will be called apm.
2532
2533if APM
2534
2535config APM_IGNORE_USER_SUSPEND
2536 bool "Ignore USER SUSPEND"
a7f7f624 2537 help
e279b6c1
SR
2538 This option will ignore USER SUSPEND requests. On machines with a
2539 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2540 series notebooks, it is necessary to say Y because of a BIOS bug.
2541
2542config APM_DO_ENABLE
2543 bool "Enable PM at boot time"
a7f7f624 2544 help
e279b6c1
SR
2545 Enable APM features at boot time. From page 36 of the APM BIOS
2546 specification: "When disabled, the APM BIOS does not automatically
2547 power manage devices, enter the Standby State, enter the Suspend
2548 State, or take power saving steps in response to CPU Idle calls."
2549 This driver will make CPU Idle calls when Linux is idle (unless this
2550 feature is turned off -- see "Do CPU IDLE calls", below). This
2551 should always save battery power, but more complicated APM features
2552 will be dependent on your BIOS implementation. You may need to turn
2553 this option off if your computer hangs at boot time when using APM
2554 support, or if it beeps continuously instead of suspending. Turn
2555 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2556 T400CDT. This is off by default since most machines do fine without
2557 this feature.
2558
2559config APM_CPU_IDLE
dd8af076 2560 depends on CPU_IDLE
e279b6c1 2561 bool "Make CPU Idle calls when idle"
a7f7f624 2562 help
e279b6c1
SR
2563 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2564 On some machines, this can activate improved power savings, such as
2565 a slowed CPU clock rate, when the machine is idle. These idle calls
2566 are made after the idle loop has run for some length of time (e.g.,
2567 333 mS). On some machines, this will cause a hang at boot time or
2568 whenever the CPU becomes idle. (On machines with more than one CPU,
2569 this option does nothing.)
2570
2571config APM_DISPLAY_BLANK
2572 bool "Enable console blanking using APM"
a7f7f624 2573 help
e279b6c1
SR
2574 Enable console blanking using the APM. Some laptops can use this to
2575 turn off the LCD backlight when the screen blanker of the Linux
2576 virtual console blanks the screen. Note that this is only used by
2577 the virtual console screen blanker, and won't turn off the backlight
2578 when using the X Window system. This also doesn't have anything to
2579 do with your VESA-compliant power-saving monitor. Further, this
2580 option doesn't work for all laptops -- it might not turn off your
2581 backlight at all, or it might print a lot of errors to the console,
2582 especially if you are using gpm.
2583
2584config APM_ALLOW_INTS
2585 bool "Allow interrupts during APM BIOS calls"
a7f7f624 2586 help
e279b6c1
SR
2587 Normally we disable external interrupts while we are making calls to
2588 the APM BIOS as a measure to lessen the effects of a badly behaving
2589 BIOS implementation. The BIOS should reenable interrupts if it
2590 needs to. Unfortunately, some BIOSes do not -- especially those in
2591 many of the newer IBM Thinkpads. If you experience hangs when you
2592 suspend, try setting this to Y. Otherwise, say N.
2593
e279b6c1
SR
2594endif # APM
2595
bb0a56ec 2596source "drivers/cpufreq/Kconfig"
e279b6c1
SR
2597
2598source "drivers/cpuidle/Kconfig"
2599
27471fdb
AH
2600source "drivers/idle/Kconfig"
2601
e279b6c1
SR
2602endmenu
2603
2604
2605menu "Bus options (PCI etc.)"
2606
e279b6c1
SR
2607choice
2608 prompt "PCI access mode"
efefa6f6 2609 depends on X86_32 && PCI
e279b6c1 2610 default PCI_GOANY
a7f7f624 2611 help
e279b6c1
SR
2612 On PCI systems, the BIOS can be used to detect the PCI devices and
2613 determine their configuration. However, some old PCI motherboards
2614 have BIOS bugs and may crash if this is done. Also, some embedded
2615 PCI-based systems don't have any BIOS at all. Linux can also try to
2616 detect the PCI hardware directly without using the BIOS.
2617
2618 With this option, you can specify how Linux should detect the
2619 PCI devices. If you choose "BIOS", the BIOS will be used,
2620 if you choose "Direct", the BIOS won't be used, and if you
2621 choose "MMConfig", then PCI Express MMCONFIG will be used.
2622 If you choose "Any", the kernel will try MMCONFIG, then the
2623 direct access method and falls back to the BIOS if that doesn't
2624 work. If unsure, go with the default, which is "Any".
2625
2626config PCI_GOBIOS
2627 bool "BIOS"
2628
2629config PCI_GOMMCONFIG
2630 bool "MMConfig"
2631
2632config PCI_GODIRECT
2633 bool "Direct"
2634
3ef0e1f8 2635config PCI_GOOLPC
76fb6570 2636 bool "OLPC XO-1"
3ef0e1f8
AS
2637 depends on OLPC
2638
2bdd1b03
AS
2639config PCI_GOANY
2640 bool "Any"
2641
e279b6c1
SR
2642endchoice
2643
2644config PCI_BIOS
3c2362e6 2645 def_bool y
efefa6f6 2646 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
e279b6c1
SR
2647
2648# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2649config PCI_DIRECT
3c2362e6 2650 def_bool y
0aba496f 2651 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
e279b6c1
SR
2652
2653config PCI_MMCONFIG
b45c9f36
JK
2654 bool "Support mmconfig PCI config space access" if X86_64
2655 default y
4590d98f 2656 depends on PCI && (ACPI || JAILHOUSE_GUEST)
b45c9f36 2657 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
e279b6c1 2658
3ef0e1f8 2659config PCI_OLPC
2bdd1b03
AS
2660 def_bool y
2661 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
3ef0e1f8 2662
b5401a96
AN
2663config PCI_XEN
2664 def_bool y
2665 depends on PCI && XEN
b5401a96 2666
8364e1f8
JK
2667config MMCONF_FAM10H
2668 def_bool y
2669 depends on X86_64 && PCI_MMCONFIG && ACPI
e279b6c1 2670
3f6ea84a 2671config PCI_CNB20LE_QUIRK
6a108a14 2672 bool "Read CNB20LE Host Bridge Windows" if EXPERT
6ea30386 2673 depends on PCI
3f6ea84a
IS
2674 help
2675 Read the PCI windows out of the CNB20LE host bridge. This allows
2676 PCI hotplug to work on systems with the CNB20LE chipset which do
2677 not have ACPI.
2678
64a5fed6
BH
2679 There's no public spec for this chipset, and this functionality
2680 is known to be incomplete.
2681
2682 You should say N unless you know you need this.
2683
3a495511 2684config ISA_BUS
17a2a129 2685 bool "ISA bus support on modern systems" if EXPERT
3a495511 2686 help
17a2a129
WBG
2687 Expose ISA bus device drivers and options available for selection and
2688 configuration. Enable this option if your target machine has an ISA
2689 bus. ISA is an older system, displaced by PCI and newer bus
2690 architectures -- if your target machine is modern, it probably does
2691 not have an ISA bus.
3a495511
WBG
2692
2693 If unsure, say N.
2694
1c00f016 2695# x86_64 have no ISA slots, but can have ISA-style DMA.
e279b6c1 2696config ISA_DMA_API
1c00f016
DR
2697 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2698 default y
2699 help
2700 Enables ISA-style DMA support for devices requiring such controllers.
2701 If unsure, say Y.
e279b6c1 2702
51e68d05
LT
2703if X86_32
2704
e279b6c1
SR
2705config ISA
2706 bool "ISA support"
a7f7f624 2707 help
e279b6c1
SR
2708 Find out whether you have ISA slots on your motherboard. ISA is the
2709 name of a bus system, i.e. the way the CPU talks to the other stuff
2710 inside your box. Other bus systems are PCI, EISA, MicroChannel
2711 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2712 newer boards don't support it. If you have ISA, say Y, otherwise N.
2713
e279b6c1
SR
2714config SCx200
2715 tristate "NatSemi SCx200 support"
a7f7f624 2716 help
e279b6c1
SR
2717 This provides basic support for National Semiconductor's
2718 (now AMD's) Geode processors. The driver probes for the
2719 PCI-IDs of several on-chip devices, so its a good dependency
2720 for other scx200_* drivers.
2721
2722 If compiled as a module, the driver is named scx200.
2723
2724config SCx200HR_TIMER
2725 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
592913ec 2726 depends on SCx200
e279b6c1 2727 default y
a7f7f624 2728 help
e279b6c1
SR
2729 This driver provides a clocksource built upon the on-chip
2730 27MHz high-resolution timer. Its also a workaround for
2731 NSC Geode SC-1100's buggy TSC, which loses time when the
2732 processor goes idle (as is done by the scheduler). The
2733 other workaround is idle=poll boot option.
2734
3ef0e1f8
AS
2735config OLPC
2736 bool "One Laptop Per Child support"
54008979 2737 depends on !X86_PAE
3c554946 2738 select GPIOLIB
dc3119e7 2739 select OF
45bb1674 2740 select OF_PROMTREE
b4e51854 2741 select IRQ_DOMAIN
0c3d931b 2742 select OLPC_EC
a7f7f624 2743 help
3ef0e1f8
AS
2744 Add support for detecting the unique features of the OLPC
2745 XO hardware.
2746
a3128588
DD
2747config OLPC_XO1_PM
2748 bool "OLPC XO-1 Power Management"
fa112cf1 2749 depends on OLPC && MFD_CS5535=y && PM_SLEEP
a7f7f624 2750 help
97c4cb71 2751 Add support for poweroff and suspend of the OLPC XO-1 laptop.
bf1ebf00 2752
cfee9597
DD
2753config OLPC_XO1_RTC
2754 bool "OLPC XO-1 Real Time Clock"
2755 depends on OLPC_XO1_PM && RTC_DRV_CMOS
a7f7f624 2756 help
cfee9597
DD
2757 Add support for the XO-1 real time clock, which can be used as a
2758 programmable wakeup source.
2759
7feda8e9
DD
2760config OLPC_XO1_SCI
2761 bool "OLPC XO-1 SCI extras"
92e830f2 2762 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
ed8e47fe 2763 depends on INPUT=y
d8d01a63 2764 select POWER_SUPPLY
a7f7f624 2765 help
7feda8e9 2766 Add support for SCI-based features of the OLPC XO-1 laptop:
7bc74b3d 2767 - EC-driven system wakeups
7feda8e9 2768 - Power button
7bc74b3d 2769 - Ebook switch
2cf2baea 2770 - Lid switch
e1040ac6
DD
2771 - AC adapter status updates
2772 - Battery status updates
7feda8e9 2773
a0f30f59
DD
2774config OLPC_XO15_SCI
2775 bool "OLPC XO-1.5 SCI extras"
d8d01a63
DD
2776 depends on OLPC && ACPI
2777 select POWER_SUPPLY
a7f7f624 2778 help
a0f30f59
DD
2779 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2780 - EC-driven system wakeups
2781 - AC adapter status updates
2782 - Battery status updates
bf1ebf00 2783
d4f3e350
EW
2784config ALIX
2785 bool "PCEngines ALIX System Support (LED setup)"
2786 select GPIOLIB
a7f7f624 2787 help
d4f3e350
EW
2788 This option enables system support for the PCEngines ALIX.
2789 At present this just sets up LEDs for GPIO control on
2790 ALIX2/3/6 boards. However, other system specific setup should
2791 get added here.
2792
2793 Note: You must still enable the drivers for GPIO and LED support
2794 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2795
2796 Note: You have to set alix.force=1 for boards with Award BIOS.
2797
da4e3302
PP
2798config NET5501
2799 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2800 select GPIOLIB
a7f7f624 2801 help
da4e3302
PP
2802 This option enables system support for the Soekris Engineering net5501.
2803
3197059a
PP
2804config GEOS
2805 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2806 select GPIOLIB
2807 depends on DMI
a7f7f624 2808 help
3197059a
PP
2809 This option enables system support for the Traverse Technologies GEOS.
2810
7d029125
VD
2811config TS5500
2812 bool "Technologic Systems TS-5500 platform support"
2813 depends on MELAN
2814 select CHECK_SIGNATURE
2815 select NEW_LEDS
2816 select LEDS_CLASS
a7f7f624 2817 help
7d029125
VD
2818 This option enables system support for the Technologic Systems TS-5500.
2819
bc0120fd
SR
2820endif # X86_32
2821
23ac4ae8 2822config AMD_NB
e279b6c1 2823 def_bool y
0e152cd7 2824 depends on CPU_SUP_AMD && PCI
e279b6c1 2825
e279b6c1
SR
2826endmenu
2827
2828
1572497c 2829menu "Binary Emulations"
e279b6c1
SR
2830
2831config IA32_EMULATION
2832 bool "IA32 Emulation"
2833 depends on X86_64
39f88911 2834 select ARCH_WANT_OLD_COMPAT_IPC
d1603990 2835 select BINFMT_ELF
39f88911 2836 select COMPAT_OLD_SIGACTION
a7f7f624 2837 help
5fd92e65
L
2838 Include code to run legacy 32-bit programs under a
2839 64-bit kernel. You should likely turn this on, unless you're
2840 100% sure that you don't have any 32-bit programs left.
e279b6c1
SR
2841
2842config IA32_AOUT
8f9ca475
IM
2843 tristate "IA32 a.out support"
2844 depends on IA32_EMULATION
eac61655 2845 depends on BROKEN
a7f7f624 2846 help
8f9ca475 2847 Support old a.out binaries in the 32bit emulation.
e279b6c1 2848
83a44a4f 2849config X86_X32_ABI
6ea30386 2850 bool "x32 ABI for 64-bit mode"
9b54050b 2851 depends on X86_64
aaeed6ec
NC
2852 # llvm-objcopy does not convert x86_64 .note.gnu.property or
2853 # compressed debug sections to x86_x32 properly:
2854 # https://github.com/ClangBuiltLinux/linux/issues/514
2855 # https://github.com/ClangBuiltLinux/linux/issues/1141
2856 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
a7f7f624 2857 help
5fd92e65
L
2858 Include code to run binaries for the x32 native 32-bit ABI
2859 for 64-bit processors. An x32 process gets access to the
2860 full 64-bit register file and wide data path while leaving
2861 pointers at 32 bits for smaller memory footprint.
2862
953fee1d
IM
2863config COMPAT_32
2864 def_bool y
2865 depends on IA32_EMULATION || X86_32
2866 select HAVE_UID16
2867 select OLD_SIGSUSPEND3
2868
e279b6c1 2869config COMPAT
3c2362e6 2870 def_bool y
83a44a4f 2871 depends on IA32_EMULATION || X86_X32_ABI
e279b6c1 2872
3120e25e 2873if COMPAT
e279b6c1 2874config COMPAT_FOR_U64_ALIGNMENT
3120e25e 2875 def_bool y
e279b6c1
SR
2876
2877config SYSVIPC_COMPAT
3c2362e6 2878 def_bool y
3120e25e 2879 depends on SYSVIPC
3120e25e 2880endif
ee009e4a 2881
e279b6c1
SR
2882endmenu
2883
2884
e5beae16
KP
2885config HAVE_ATOMIC_IOMAP
2886 def_bool y
2887 depends on X86_32
2888
edf88417 2889source "arch/x86/kvm/Kconfig"
5e8ebd84
JD
2890
2891source "arch/x86/Kconfig.assembler"