objtool: Find unused ENDBR instructions
[linux-2.6-block.git] / arch / x86 / Kconfig
CommitLineData
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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IM
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
942fa985 62 select ARCH_32BIT_OFF_T if X86_32
2a21ad57 63 select ARCH_CLOCKSOURCE_INIT
1f6d3a8f 64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
1e866974 65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
5c11f00b 66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
91024b3c 67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
cebc774f 68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
1e866974 69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
c763ea26 70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
c2280be8 71 select ARCH_HAS_CACHE_LINE_SIZE
fa5b6ec9 72 select ARCH_HAS_DEBUG_VIRTUAL
399145f9 73 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
21266be9 74 select ARCH_HAS_DEVMEM_IS_ALLOWED
b1a57bbf 75 select ARCH_HAS_EARLY_DEBUG if KGDB
6471b825 76 select ARCH_HAS_ELF_RANDOMIZE
72d93104 77 select ARCH_HAS_FAST_MULTIPLIER
316d097c 78 select ARCH_HAS_FILTER_PGPROT
6974f0c4 79 select ARCH_HAS_FORTIFY_SOURCE
957e3fac 80 select ARCH_HAS_GCOV_PROFILE_ALL
bece04b5 81 select ARCH_HAS_KCOV if X86_64
0c9c1d56 82 select ARCH_HAS_MEM_ENCRYPT
10bcc80e 83 select ARCH_HAS_MEMBARRIER_SYNC_CORE
0ebeea8c 84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
c763ea26 85 select ARCH_HAS_PMEM_API if X86_64
17596731 86 select ARCH_HAS_PTE_DEVMAP if X86_64
3010a5ea 87 select ARCH_HAS_PTE_SPECIAL
0aed55af 88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
ec6347bb 89 select ARCH_HAS_COPY_MC if X86_64
d2852a22 90 select ARCH_HAS_SET_MEMORY
d253ca0c 91 select ARCH_HAS_SET_DIRECT_MAP
ad21fc4f
LA
92 select ARCH_HAS_STRICT_KERNEL_RWX
93 select ARCH_HAS_STRICT_MODULE_RWX
ac1ab12a 94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
25c619e5 95 select ARCH_HAS_SYSCALL_WRAPPER
c6d30853 96 select ARCH_HAS_UBSAN_SANITIZE_ALL
7e01ccb4 97 select ARCH_HAS_DEBUG_WX
63703f37 98 select ARCH_HAS_ZONE_DMA_SET if EXPERT
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IM
99 select ARCH_HAVE_NMI_SAFE_CMPXCHG
100 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
77fbbc81 101 select ARCH_MIGHT_HAVE_PC_PARPORT
5e2c18c0 102 select ARCH_MIGHT_HAVE_PC_SERIO
3599fe12 103 select ARCH_STACKWALK
2c870e61 104 select ARCH_SUPPORTS_ACPI
6471b825 105 select ARCH_SUPPORTS_ATOMIC_RMW
5d6ad668 106 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
d283d422 107 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
6471b825 108 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
14df3267 109 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
583bfd48
NC
110 select ARCH_SUPPORTS_LTO_CLANG
111 select ARCH_SUPPORTS_LTO_CLANG_THIN
6471b825 112 select ARCH_USE_BUILTIN_BSWAP
dce44566 113 select ARCH_USE_MEMTEST
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IM
114 select ARCH_USE_QUEUED_RWLOCKS
115 select ARCH_USE_QUEUED_SPINLOCKS
2ce0d7f9 116 select ARCH_USE_SYM_ANNOTATIONS
ce4a4e56 117 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
81c22041 118 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
c763ea26 119 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
51c2ee6d 120 select ARCH_WANTS_NO_INSTR
3876d4a3 121 select ARCH_WANT_HUGE_PMD_SHARE
59612b24 122 select ARCH_WANT_LD_ORPHAN_WARN
38d8b4e6 123 select ARCH_WANTS_THP_SWAP if X86_64
b5f06f64 124 select ARCH_HAS_PARANOID_L1D_FLUSH
10916706 125 select BUILDTIME_TABLE_SORT
6471b825 126 select CLKEVT_I8253
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IM
127 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
128 select CLOCKSOURCE_WATCHDOG
6471b825 129 select DCACHE_WORD_ACCESS
3aac3ebe 130 select DYNAMIC_SIGFRAME
45471cd9
LT
131 select EDAC_ATOMIC_SCRUB
132 select EDAC_SUPPORT
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IM
133 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
134 select GENERIC_CLOCKEVENTS_MIN_ADJUST
135 select GENERIC_CMOS_UPDATE
136 select GENERIC_CPU_AUTOPROBE
61dc0f55 137 select GENERIC_CPU_VULNERABILITIES
5b7c73e0 138 select GENERIC_EARLY_IOREMAP
27d6b4d1 139 select GENERIC_ENTRY
6471b825 140 select GENERIC_IOMAP
c7d6c9dd 141 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
0fa115da 142 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
ad7a929f 143 select GENERIC_IRQ_MIGRATION if SMP
6471b825 144 select GENERIC_IRQ_PROBE
c201c917 145 select GENERIC_IRQ_RESERVATION_MODE
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IM
146 select GENERIC_IRQ_SHOW
147 select GENERIC_PENDING_IRQ if SMP
2ae27137 148 select GENERIC_PTDUMP
6471b825 149 select GENERIC_SMP_IDLE_THREAD
6471b825 150 select GENERIC_TIME_VSYSCALL
7ac87074 151 select GENERIC_GETTIMEOFDAY
550a77a7 152 select GENERIC_VDSO_TIME_NS
39656e83 153 select GUP_GET_PTE_LOW_HIGH if X86_PAE
17e5888e 154 select HARDIRQS_SW_RESEND
7edaeb68 155 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
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IM
156 select HAVE_ACPI_APEI if ACPI
157 select HAVE_ACPI_APEI_NMI if ACPI
158 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
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IM
159 select HAVE_ARCH_AUDITSYSCALL
160 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
161 select HAVE_ARCH_JUMP_LABEL
b34006c4 162 select HAVE_ARCH_JUMP_LABEL_RELATIVE
d17a1d97 163 select HAVE_ARCH_KASAN if X86_64
0609ae01 164 select HAVE_ARCH_KASAN_VMALLOC if X86_64
1dc0da6e 165 select HAVE_ARCH_KFENCE
6471b825 166 select HAVE_ARCH_KGDB
9e08f57d
DC
167 select HAVE_ARCH_MMAP_RND_BITS if MMU
168 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
1b028f78 169 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
271ca788 170 select HAVE_ARCH_PREL32_RELOCATIONS
6471b825 171 select HAVE_ARCH_SECCOMP_FILTER
f7d83c1c 172 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
afaef01c 173 select HAVE_ARCH_STACKLEAK
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IM
174 select HAVE_ARCH_TRACEHOOK
175 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
a00cc7d9 176 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
b64d8d1e 177 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
7677f7fd 178 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
e37e43a4 179 select HAVE_ARCH_VMAP_STACK if X86_64
fe950f60 180 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
c763ea26 181 select HAVE_ARCH_WITHIN_STACK_FRAMES
2ff2b7ec 182 select HAVE_ASM_MODVERSIONS
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IM
183 select HAVE_CMPXCHG_DOUBLE
184 select HAVE_CMPXCHG_LOCAL
185 select HAVE_CONTEXT_TRACKING if X86_64
d1f250e2 186 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
cf4db259 187 select HAVE_C_RECORDMCOUNT
6dafca97 188 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
4ed308c4 189 select HAVE_BUILDTIME_MCOUNT_SORT
6471b825 190 select HAVE_DEBUG_KMEMLEAK
6471b825 191 select HAVE_DMA_CONTIGUOUS
677aa9f7 192 select HAVE_DYNAMIC_FTRACE
06aeaaea 193 select HAVE_DYNAMIC_FTRACE_WITH_REGS
02a474ca 194 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
562955fe 195 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
c316eb44 196 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
503e4510 197 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
03f5781b 198 select HAVE_EBPF_JIT
58340a07 199 select HAVE_EFFICIENT_UNALIGNED_ACCESS
6630a8e5 200 select HAVE_EISA
5f56a5df 201 select HAVE_EXIT_THREAD
67a929e0 202 select HAVE_FAST_GUP
644e0e8d 203 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
6471b825 204 select HAVE_FTRACE_MCOUNT_RECORD
4a30e4c9 205 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
6471b825 206 select HAVE_FUNCTION_TRACER
6b90bd4b 207 select HAVE_GCC_PLUGINS
6471b825 208 select HAVE_HW_BREAKPOINT
6471b825 209 select HAVE_IOREMAP_PROT
624db9ea 210 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
6471b825 211 select HAVE_IRQ_TIME_ACCOUNTING
2e9f3bdd 212 select HAVE_KERNEL_BZIP2
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IM
213 select HAVE_KERNEL_GZIP
214 select HAVE_KERNEL_LZ4
2e9f3bdd 215 select HAVE_KERNEL_LZMA
13510997 216 select HAVE_KERNEL_LZO
6471b825 217 select HAVE_KERNEL_XZ
fb46d057 218 select HAVE_KERNEL_ZSTD
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IM
219 select HAVE_KPROBES
220 select HAVE_KPROBES_ON_FTRACE
540adea3 221 select HAVE_FUNCTION_ERROR_INJECTION
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IM
222 select HAVE_KRETPROBES
223 select HAVE_KVM
224 select HAVE_LIVEPATCH if X86_64
0102752e 225 select HAVE_MIXED_BREAKPOINTS_REGS
ee9f8fce 226 select HAVE_MOD_ARCH_SPECIFIC
9f132f7e 227 select HAVE_MOVE_PMD
be37c98d 228 select HAVE_MOVE_PUD
42a0bb3f 229 select HAVE_NMI
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IM
230 select HAVE_OPTPROBES
231 select HAVE_PCSPKR_PLATFORM
232 select HAVE_PERF_EVENTS
c01d4323 233 select HAVE_PERF_EVENTS_NMI
92e5aae4 234 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
eb01d42a 235 select HAVE_PCI
c5e63197 236 select HAVE_PERF_REGS
c5ebcedb 237 select HAVE_PERF_USER_STACK_DUMP
ff2e6d72 238 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
00998085 239 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
6471b825 240 select HAVE_REGS_AND_STACK_ACCESS_API
6415b38b 241 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
3c88ee19 242 select HAVE_FUNCTION_ARG_ACCESS_API
7ecd19cf 243 select HAVE_SETUP_PER_CPU_AREA
cd1a41ce 244 select HAVE_SOFTIRQ_ON_OWN_STACK
d148eac0 245 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
c763ea26 246 select HAVE_STACK_VALIDATION if X86_64
e6d6c071 247 select HAVE_STATIC_CALL
1e7e4788 248 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
6ef869e0 249 select HAVE_PREEMPT_DYNAMIC
d6761b8f 250 select HAVE_RSEQ
6471b825 251 select HAVE_SYSCALL_TRACEPOINTS
6471b825 252 select HAVE_UNSTABLE_SCHED_CLOCK
7c68af6e 253 select HAVE_USER_RETURN_NOTIFIER
7ac87074 254 select HAVE_GENERIC_VDSO
05736e4a 255 select HOTPLUG_SMT if SMP
c0185808 256 select IRQ_FORCED_THREADING
7ecd19cf
KW
257 select NEED_PER_CPU_EMBED_FIRST_CHUNK
258 select NEED_PER_CPU_PAGE_FIRST_CHUNK
86596f0a 259 select NEED_SG_DMA_LENGTH
2eac9c2d 260 select PCI_DOMAINS if PCI
625210cf 261 select PCI_LOCKLESS_CONFIG if PCI
6471b825 262 select PERF_EVENTS
3195ef59 263 select RTC_LIB
d6faca40 264 select RTC_MC146818_LIB
6471b825 265 select SPARSE_IRQ
83fe27ea 266 select SRCU
1e7e4788 267 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
6471b825 268 select SYSCTL_EXCEPTION_TRACE
15f4eae7 269 select THREAD_INFO_IN_TASK
4aae683f 270 select TRACE_IRQFLAGS_SUPPORT
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IM
271 select USER_STACKTRACE_SUPPORT
272 select VIRT_TO_BUS
3b02a051 273 select HAVE_ARCH_KCSAN if X86_64
6471b825 274 select X86_FEATURE_NAMES if PROC_FS
0c608dad 275 select PROC_PID_ARCH_STATUS if PROC_FS
50468e43 276 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
9e2b4be3 277 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
7d8330a5 278
ba7e4d13 279config INSTRUCTION_DECODER
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JB
280 def_bool y
281 depends on KPROBES || PERF_EVENTS || UPROBES
ba7e4d13 282
51b26ada
LT
283config OUTPUT_FORMAT
284 string
285 default "elf32-i386" if X86_32
286 default "elf64-x86-64" if X86_64
287
8d5fffb9 288config LOCKDEP_SUPPORT
3c2362e6 289 def_bool y
8d5fffb9
SR
290
291config STACKTRACE_SUPPORT
3c2362e6 292 def_bool y
8d5fffb9 293
8d5fffb9 294config MMU
3c2362e6 295 def_bool y
8d5fffb9 296
9e08f57d
DC
297config ARCH_MMAP_RND_BITS_MIN
298 default 28 if 64BIT
299 default 8
300
301config ARCH_MMAP_RND_BITS_MAX
302 default 32 if 64BIT
303 default 16
304
305config ARCH_MMAP_RND_COMPAT_BITS_MIN
306 default 8
307
308config ARCH_MMAP_RND_COMPAT_BITS_MAX
309 default 16
310
8d5fffb9
SR
311config SBUS
312 bool
313
314config GENERIC_ISA_DMA
3120e25e
JB
315 def_bool y
316 depends on ISA_DMA_API
8d5fffb9 317
8d5fffb9 318config GENERIC_BUG
3c2362e6 319 def_bool y
8d5fffb9 320 depends on BUG
b93a531e
JB
321 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
322
323config GENERIC_BUG_RELATIVE_POINTERS
324 bool
8d5fffb9 325
8d5fffb9 326config ARCH_MAY_HAVE_PC_FDC
3120e25e
JB
327 def_bool y
328 depends on ISA_DMA_API
8d5fffb9 329
1032c0ba
SR
330config GENERIC_CALIBRATE_DELAY
331 def_bool y
332
9a0b8415 333config ARCH_HAS_CPU_RELAX
334 def_bool y
335
316d097c
DH
336config ARCH_HAS_FILTER_PGPROT
337 def_bool y
338
801e4062
JB
339config ARCH_HIBERNATION_POSSIBLE
340 def_bool y
801e4062 341
d7109fe3
AS
342config ARCH_NR_GPIO
343 int
344 default 1024 if X86_64
345 default 512
346
f4cb5700
JB
347config ARCH_SUSPEND_POSSIBLE
348 def_bool y
f4cb5700 349
53313b2c
SC
350config ARCH_WANT_GENERAL_HUGETLB
351 def_bool y
352
8d5fffb9 353config AUDIT_ARCH
e0fd24a3 354 def_bool y if X86_64
8d5fffb9 355
d6f2d75a
AR
356config KASAN_SHADOW_OFFSET
357 hex
358 depends on KASAN
359 default 0xdffffc0000000000
360
69575d38
SW
361config HAVE_INTEL_TXT
362 def_bool y
6ea30386 363 depends on INTEL_IOMMU && ACPI
69575d38 364
6b0c3d44
SR
365config X86_32_SMP
366 def_bool y
367 depends on X86_32 && SMP
368
369config X86_64_SMP
370 def_bool y
371 depends on X86_64 && SMP
372
2b144498
SD
373config ARCH_SUPPORTS_UPROBES
374 def_bool y
375
d20642f0
RH
376config FIX_EARLYCON_MEM
377 def_bool y
378
94d49eb3
KS
379config DYNAMIC_PHYSICAL_MASK
380 bool
381
98233368
KS
382config PGTABLE_LEVELS
383 int
77ef56e4 384 default 5 if X86_5LEVEL
98233368
KS
385 default 4 if X86_64
386 default 3 if X86_PAE
387 default 2
388
2a61f474
MY
389config CC_HAS_SANE_STACKPROTECTOR
390 bool
391 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
392 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
393 help
394 We have to make sure stack protector is unconditionally disabled if
3fb0fdb3
AL
395 the compiler produces broken code or if it does not let us control
396 the segment on 32-bit kernels.
2a61f474 397
506f1d07
SR
398menu "Processor type and features"
399
506f1d07
SR
400config SMP
401 bool "Symmetric multi-processing support"
a7f7f624 402 help
506f1d07 403 This enables support for systems with more than one CPU. If you have
4a474157
RG
404 a system with only one CPU, say N. If you have a system with more
405 than one CPU, say Y.
506f1d07 406
4a474157 407 If you say N here, the kernel will run on uni- and multiprocessor
506f1d07
SR
408 machines, but will use only one CPU of a multiprocessor machine. If
409 you say Y here, the kernel will run on many, but not all,
4a474157 410 uniprocessor machines. On a uniprocessor machine, the kernel
506f1d07
SR
411 will run faster if you say N here.
412
413 Note that if you say Y here and choose architecture "586" or
414 "Pentium" under "Processor family", the kernel will not work on 486
415 architectures. Similarly, multiprocessor kernels for the "PPro"
416 architecture may not work on all Pentium based boards.
417
418 People using multiprocessor machines who say Y here should also say
419 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
420 Management" code will be disabled if you say Y here.
421
cb1aaebe 422 See also <file:Documentation/x86/i386/IO-APIC.rst>,
4f4cfa6c 423 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
506f1d07
SR
424 <http://www.tldp.org/docs.html#howto>.
425
426 If you don't know what to do here, say N.
427
9def39be
JT
428config X86_FEATURE_NAMES
429 bool "Processor feature human-readable names" if EMBEDDED
430 default y
a7f7f624 431 help
9def39be
JT
432 This option compiles in a table of x86 feature bits and corresponding
433 names. This is required to support /proc/cpuinfo and a few kernel
434 messages. You can disable this to save space, at the expense of
435 making those few kernel messages show numeric feature bits instead.
436
437 If in doubt, say Y.
438
06cd9a7d
YL
439config X86_X2APIC
440 bool "Support x2apic"
19e3d60d 441 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
a7f7f624 442 help
06cd9a7d
YL
443 This enables x2apic support on CPUs that have this feature.
444
445 This allows 32-bit apic IDs (so it can support very large systems),
446 and accesses the local apic via MSRs not via mmio.
447
06cd9a7d
YL
448 If you don't know what to do here, say N.
449
6695c85b 450config X86_MPPARSE
4590d98f 451 bool "Enable MPS table" if ACPI
7a527688 452 default y
5ab74722 453 depends on X86_LOCAL_APIC
a7f7f624 454 help
6695c85b
YL
455 For old smp systems that do not have proper acpi support. Newer systems
456 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
6695c85b 457
ddd70cf9 458config GOLDFISH
b03b016f
KK
459 def_bool y
460 depends on X86_GOLDFISH
ddd70cf9 461
76b04384
DW
462config RETPOLINE
463 bool "Avoid speculative indirect branches in kernel"
464 default y
465 help
466 Compile kernel with the retpoline compiler options to guard against
467 kernel-to-user data leaks by avoiding speculative indirect
468 branches. Requires a compiler with -mindirect-branch=thunk-extern
469 support for full protection. The kernel may run slower.
470
e463a09a
PZ
471config CC_HAS_SLS
472 def_bool $(cc-option,-mharden-sls=all)
473
474config SLS
475 bool "Mitigate Straight-Line-Speculation"
476 depends on CC_HAS_SLS && X86_64
477 default n
478 help
479 Compile the kernel with straight-line-speculation options to guard
480 against straight line speculation. The kernel image might be slightly
481 larger.
482
e6d42931
JW
483config X86_CPU_RESCTRL
484 bool "x86 CPU resource control support"
6fe07ce3 485 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
59fe5a77 486 select KERNFS
e79f15a4 487 select PROC_CPU_RESCTRL if PROC_FS
78e99b4a 488 help
e6d42931 489 Enable x86 CPU resource control support.
6fe07ce3
BM
490
491 Provide support for the allocation and monitoring of system resources
492 usage by the CPU.
493
494 Intel calls this Intel Resource Director Technology
495 (Intel(R) RDT). More information about RDT can be found in the
496 Intel x86 Architecture Software Developer Manual.
497
498 AMD calls this AMD Platform Quality of Service (AMD QoS).
499 More information about AMD QoS can be found in the AMD64 Technology
500 Platform Quality of Service Extensions manual.
78e99b4a
FY
501
502 Say N if unsure.
503
8425091f 504if X86_32
a0d0bb4d
RD
505config X86_BIGSMP
506 bool "Support for big SMP systems with more than 8 CPUs"
507 depends on SMP
a7f7f624 508 help
e133f6ea 509 This option is needed for the systems that have more than 8 CPUs.
a0d0bb4d 510
c5c606d9
RT
511config X86_EXTENDED_PLATFORM
512 bool "Support for extended (non-PC) x86 platforms"
513 default y
a7f7f624 514 help
06ac8346
IM
515 If you disable this option then the kernel will only support
516 standard PC platforms. (which covers the vast majority of
517 systems out there.)
518
8425091f
RT
519 If you enable this option then you'll be able to select support
520 for the following (non-PC) 32 bit x86 platforms:
cb7b8023 521 Goldfish (Android emulator)
8425091f 522 AMD Elan
8425091f
RT
523 RDC R-321x SoC
524 SGI 320/540 (Visual Workstation)
83125a3a 525 STA2X11-based (e.g. Northville)
3f4110a4 526 Moorestown MID devices
06ac8346
IM
527
528 If you have one of these systems, or if you want to build a
529 generic distribution kernel, say Y here - otherwise say N.
8425091f 530endif
06ac8346 531
8425091f
RT
532if X86_64
533config X86_EXTENDED_PLATFORM
534 bool "Support for extended (non-PC) x86 platforms"
535 default y
a7f7f624 536 help
8425091f
RT
537 If you disable this option then the kernel will only support
538 standard PC platforms. (which covers the vast majority of
539 systems out there.)
540
541 If you enable this option then you'll be able to select support
542 for the following (non-PC) 64 bit x86 platforms:
44b111b5 543 Numascale NumaChip
8425091f
RT
544 ScaleMP vSMP
545 SGI Ultraviolet
546
547 If you have one of these systems, or if you want to build a
548 generic distribution kernel, say Y here - otherwise say N.
549endif
c5c606d9
RT
550# This is an alphabetically sorted list of 64 bit extended platforms
551# Please maintain the alphabetic order if and when there are additions
44b111b5
SP
552config X86_NUMACHIP
553 bool "Numascale NumaChip"
554 depends on X86_64
555 depends on X86_EXTENDED_PLATFORM
556 depends on NUMA
557 depends on SMP
558 depends on X86_X2APIC
f9726bfd 559 depends on PCI_MMCONFIG
a7f7f624 560 help
44b111b5
SP
561 Adds support for Numascale NumaChip large-SMP systems. Needed to
562 enable more than ~168 cores.
563 If you don't have one of these, you should say N here.
506f1d07 564
c5c606d9
RT
565config X86_VSMP
566 bool "ScaleMP vSMP"
6276a074 567 select HYPERVISOR_GUEST
c5c606d9
RT
568 select PARAVIRT
569 depends on X86_64 && PCI
570 depends on X86_EXTENDED_PLATFORM
ead91d4b 571 depends on SMP
a7f7f624 572 help
c5c606d9
RT
573 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
574 supposed to run on these EM64T-based machines. Only choose this option
575 if you have one of these machines.
5e3a77e9 576
03b48632
NP
577config X86_UV
578 bool "SGI Ultraviolet"
579 depends on X86_64
c5c606d9 580 depends on X86_EXTENDED_PLATFORM
54c28d29 581 depends on NUMA
1ecb4ae5 582 depends on EFI
c2209ea5 583 depends on KEXEC_CORE
9d6c26e7 584 depends on X86_X2APIC
1222e564 585 depends on PCI
a7f7f624 586 help
03b48632
NP
587 This option is needed in order to support SGI Ultraviolet systems.
588 If you don't have one of these, you should say N here.
589
c5c606d9
RT
590# Following is an alphabetically sorted list of 32 bit extended platforms
591# Please maintain the alphabetic order if and when there are additions
506f1d07 592
ddd70cf9 593config X86_GOLDFISH
b03b016f
KK
594 bool "Goldfish (Virtual Platform)"
595 depends on X86_EXTENDED_PLATFORM
a7f7f624 596 help
ddd70cf9
JN
597 Enable support for the Goldfish virtual platform used primarily
598 for Android development. Unless you are building for the Android
599 Goldfish emulator say N here.
600
c751e17b
TG
601config X86_INTEL_CE
602 bool "CE4100 TV platform"
603 depends on PCI
604 depends on PCI_GODIRECT
6084a6e2 605 depends on X86_IO_APIC
c751e17b
TG
606 depends on X86_32
607 depends on X86_EXTENDED_PLATFORM
37bc9f50 608 select X86_REBOOTFIXUPS
da6b737b
SAS
609 select OF
610 select OF_EARLY_FLATTREE
a7f7f624 611 help
c751e17b
TG
612 Select for the Intel CE media processor (CE4100) SOC.
613 This option compiles in support for the CE4100 SOC for settop
614 boxes and media devices.
615
4cb9b00f 616config X86_INTEL_MID
43605ef1 617 bool "Intel MID platform support"
43605ef1 618 depends on X86_EXTENDED_PLATFORM
edc6bc78 619 depends on X86_PLATFORM_DEVICES
1ea7c673 620 depends on PCI
3fda5bb4 621 depends on X86_64 || (PCI_GOANY && X86_32)
1ea7c673 622 depends on X86_IO_APIC
4cb9b00f 623 select I2C
7c9c3a1e 624 select DW_APB_TIMER
54b34aa0 625 select INTEL_SCU_PCI
a7f7f624 626 help
4cb9b00f
DC
627 Select to build a kernel capable of supporting Intel MID (Mobile
628 Internet Device) platform systems which do not have the PCI legacy
629 interfaces. If you are building for a PC class system say N here.
1ea7c673 630
4cb9b00f
DC
631 Intel MID platforms are based on an Intel processor and chipset which
632 consume less power than most of the x86 derivatives.
43605ef1 633
8bbc2a13
BD
634config X86_INTEL_QUARK
635 bool "Intel Quark platform support"
636 depends on X86_32
637 depends on X86_EXTENDED_PLATFORM
638 depends on X86_PLATFORM_DEVICES
639 depends on X86_TSC
640 depends on PCI
641 depends on PCI_GOANY
642 depends on X86_IO_APIC
643 select IOSF_MBI
644 select INTEL_IMR
9ab6eb51 645 select COMMON_CLK
a7f7f624 646 help
8bbc2a13
BD
647 Select to include support for Quark X1000 SoC.
648 Say Y here if you have a Quark based system such as the Arduino
649 compatible Intel Galileo.
650
3d48aab1
MW
651config X86_INTEL_LPSS
652 bool "Intel Low Power Subsystem Support"
5962dd22 653 depends on X86 && ACPI && PCI
3d48aab1 654 select COMMON_CLK
0f531431 655 select PINCTRL
eebb3e8d 656 select IOSF_MBI
a7f7f624 657 help
3d48aab1
MW
658 Select to build support for Intel Low Power Subsystem such as
659 found on Intel Lynxpoint PCH. Selecting this option enables
0f531431
MN
660 things like clock tree (common clock framework) and pincontrol
661 which are needed by the LPSS peripheral drivers.
3d48aab1 662
92082a88
KX
663config X86_AMD_PLATFORM_DEVICE
664 bool "AMD ACPI2Platform devices support"
665 depends on ACPI
666 select COMMON_CLK
667 select PINCTRL
a7f7f624 668 help
92082a88
KX
669 Select to interpret AMD specific ACPI device to platform device
670 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
671 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
672 implemented under PINCTRL subsystem.
673
ced3ce76
DB
674config IOSF_MBI
675 tristate "Intel SoC IOSF Sideband support for SoC platforms"
676 depends on PCI
a7f7f624 677 help
ced3ce76
DB
678 This option enables sideband register access support for Intel SoC
679 platforms. On these platforms the IOSF sideband is used in lieu of
680 MSR's for some register accesses, mostly but not limited to thermal
681 and power. Drivers may query the availability of this device to
682 determine if they need the sideband in order to work on these
683 platforms. The sideband is available on the following SoC products.
684 This list is not meant to be exclusive.
685 - BayTrail
686 - Braswell
687 - Quark
688
689 You should say Y if you are running a kernel on one of these SoC's.
690
ed2226bd
DB
691config IOSF_MBI_DEBUG
692 bool "Enable IOSF sideband access through debugfs"
693 depends on IOSF_MBI && DEBUG_FS
a7f7f624 694 help
ed2226bd
DB
695 Select this option to expose the IOSF sideband access registers (MCR,
696 MDR, MCRX) through debugfs to write and read register information from
697 different units on the SoC. This is most useful for obtaining device
698 state information for debug and analysis. As this is a general access
699 mechanism, users of this option would have specific knowledge of the
700 device they want to access.
701
702 If you don't require the option or are in doubt, say N.
703
c5c606d9
RT
704config X86_RDC321X
705 bool "RDC R-321x SoC"
506f1d07 706 depends on X86_32
c5c606d9
RT
707 depends on X86_EXTENDED_PLATFORM
708 select M486
709 select X86_REBOOTFIXUPS
a7f7f624 710 help
c5c606d9
RT
711 This option is needed for RDC R-321x system-on-chip, also known
712 as R-8610-(G).
713 If you don't have one of these chips, you should say N here.
714
e0c7ae37 715config X86_32_NON_STANDARD
9c398017
IM
716 bool "Support non-standard 32-bit SMP architectures"
717 depends on X86_32 && SMP
c5c606d9 718 depends on X86_EXTENDED_PLATFORM
a7f7f624 719 help
b5660ba7
PA
720 This option compiles in the bigsmp and STA2X11 default
721 subarchitectures. It is intended for a generic binary
722 kernel. If you select them all, kernel will probe it one by
723 one and will fallback to default.
d49c4288 724
c5c606d9 725# Alphabetically sorted list of Non standard 32 bit platforms
d49c4288 726
d949f36f 727config X86_SUPPORTS_MEMORY_FAILURE
6fc108a0 728 def_bool y
d949f36f
LT
729 # MCE code calls memory_failure():
730 depends on X86_MCE
731 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
d949f36f
LT
732 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
733 depends on X86_64 || !SPARSEMEM
734 select ARCH_SUPPORTS_MEMORY_FAILURE
d949f36f 735
83125a3a
AR
736config STA2X11
737 bool "STA2X11 Companion Chip Support"
738 depends on X86_32_NON_STANDARD && PCI
83125a3a
AR
739 select SWIOTLB
740 select MFD_STA2X11
0145071b 741 select GPIOLIB
a7f7f624 742 help
83125a3a
AR
743 This adds support for boards based on the STA2X11 IO-Hub,
744 a.k.a. "ConneXt". The chip is used in place of the standard
745 PC chipset, so all "standard" peripherals are missing. If this
746 option is selected the kernel will still be able to boot on
747 standard PC machines.
748
82148d1d
S
749config X86_32_IRIS
750 tristate "Eurobraille/Iris poweroff module"
751 depends on X86_32
a7f7f624 752 help
82148d1d
S
753 The Iris machines from EuroBraille do not have APM or ACPI support
754 to shut themselves down properly. A special I/O sequence is
755 needed to do so, which is what this module does at
756 kernel shutdown.
757
758 This is only for Iris machines from EuroBraille.
759
760 If unused, say N.
761
ae1e9130 762config SCHED_OMIT_FRAME_POINTER
3c2362e6
HH
763 def_bool y
764 prompt "Single-depth WCHAN output"
a87d0914 765 depends on X86
a7f7f624 766 help
506f1d07
SR
767 Calculate simpler /proc/<PID>/wchan values. If this option
768 is disabled then wchan values will recurse back to the
769 caller function. This provides more accurate wchan values,
770 at the expense of slightly more scheduling overhead.
771
772 If in doubt, say "Y".
773
6276a074
BP
774menuconfig HYPERVISOR_GUEST
775 bool "Linux guest support"
a7f7f624 776 help
6276a074
BP
777 Say Y here to enable options for running Linux under various hyper-
778 visors. This option enables basic hypervisor detection and platform
779 setup.
506f1d07 780
6276a074
BP
781 If you say N, all options in this submenu will be skipped and
782 disabled, and Linux guest support won't be built in.
506f1d07 783
6276a074 784if HYPERVISOR_GUEST
506f1d07 785
e61bd94a
EPH
786config PARAVIRT
787 bool "Enable paravirtualization code"
a0e2bf7c 788 depends on HAVE_STATIC_CALL
a7f7f624 789 help
e61bd94a
EPH
790 This changes the kernel so it can modify itself when it is run
791 under a hypervisor, potentially improving performance significantly
792 over full virtualization. However, when run without a hypervisor
793 the kernel is theoretically slower and slightly larger.
794
c00a280a
JG
795config PARAVIRT_XXL
796 bool
797
6276a074
BP
798config PARAVIRT_DEBUG
799 bool "paravirt-ops debugging"
800 depends on PARAVIRT && DEBUG_KERNEL
a7f7f624 801 help
6276a074
BP
802 Enable to debug paravirt_ops internals. Specifically, BUG if
803 a paravirt_op is missing when it is called.
804
b4ecc126
JF
805config PARAVIRT_SPINLOCKS
806 bool "Paravirtualization layer for spinlocks"
6ea30386 807 depends on PARAVIRT && SMP
a7f7f624 808 help
b4ecc126
JF
809 Paravirtualized spinlocks allow a pvops backend to replace the
810 spinlock implementation with something virtualization-friendly
811 (for example, block the virtual CPU rather than spinning).
812
4c4e4f61
R
813 It has a minimal impact on native kernels and gives a nice performance
814 benefit on paravirtualized KVM / Xen kernels.
b4ecc126 815
4c4e4f61 816 If you are unsure how to answer this question, answer Y.
b4ecc126 817
ecca2502
ZY
818config X86_HV_CALLBACK_VECTOR
819 def_bool n
820
6276a074 821source "arch/x86/xen/Kconfig"
7af192c9 822
6276a074
BP
823config KVM_GUEST
824 bool "KVM Guest support (including kvmclock)"
825 depends on PARAVIRT
826 select PARAVIRT_CLOCK
a1c4423b 827 select ARCH_CPUIDLE_HALTPOLL
b1d40575 828 select X86_HV_CALLBACK_VECTOR
6276a074 829 default y
a7f7f624 830 help
6276a074
BP
831 This option enables various optimizations for running under the KVM
832 hypervisor. It includes a paravirtualized clock, so that instead
833 of relying on a PIT (or probably other) emulation by the
834 underlying device model, the host provides the guest with
835 timing infrastructure such as time of day, and system time
506f1d07 836
a1c4423b 837config ARCH_CPUIDLE_HALTPOLL
b03b016f
KK
838 def_bool n
839 prompt "Disable host haltpoll when loading haltpoll driver"
840 help
a1c4423b
MT
841 If virtualized under KVM, disable host haltpoll.
842
7733607f
MW
843config PVH
844 bool "Support for running PVH guests"
a7f7f624 845 help
7733607f
MW
846 This option enables the PVH entry point for guest virtual machines
847 as specified in the x86/HVM direct boot ABI.
848
6276a074
BP
849config PARAVIRT_TIME_ACCOUNTING
850 bool "Paravirtual steal time accounting"
851 depends on PARAVIRT
a7f7f624 852 help
6276a074
BP
853 Select this option to enable fine granularity task steal time
854 accounting. Time spent executing other tasks in parallel with
855 the current vCPU is discounted from the vCPU power. To account for
856 that, there can be a small performance impact.
857
858 If in doubt, say N here.
859
860config PARAVIRT_CLOCK
861 bool
97349135 862
4a362601
JK
863config JAILHOUSE_GUEST
864 bool "Jailhouse non-root cell support"
abde587b 865 depends on X86_64 && PCI
87e65d05 866 select X86_PM_TIMER
a7f7f624 867 help
4a362601
JK
868 This option allows to run Linux as guest in a Jailhouse non-root
869 cell. You can leave this option disabled if you only want to start
870 Jailhouse and run Linux afterwards in the root cell.
871
ec7972c9
ZY
872config ACRN_GUEST
873 bool "ACRN Guest support"
874 depends on X86_64
498ad393 875 select X86_HV_CALLBACK_VECTOR
ec7972c9
ZY
876 help
877 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
878 a flexible, lightweight reference open-source hypervisor, built with
879 real-time and safety-criticality in mind. It is built for embedded
880 IOT with small footprint and real-time features. More details can be
881 found in https://projectacrn.org/.
882
6276a074 883endif #HYPERVISOR_GUEST
97349135 884
506f1d07
SR
885source "arch/x86/Kconfig.cpu"
886
887config HPET_TIMER
3c2362e6 888 def_bool X86_64
506f1d07 889 prompt "HPET Timer Support" if X86_32
a7f7f624 890 help
8f9ca475
IM
891 Use the IA-PC HPET (High Precision Event Timer) to manage
892 time in preference to the PIT and RTC, if a HPET is
893 present.
894 HPET is the next generation timer replacing legacy 8254s.
895 The HPET provides a stable time base on SMP
896 systems, unlike the TSC, but it is more expensive to access,
4e7f9df2
MT
897 as it is off-chip. The interface used is documented
898 in the HPET spec, revision 1.
506f1d07 899
8f9ca475
IM
900 You can safely choose Y here. However, HPET will only be
901 activated if the platform and the BIOS support this feature.
902 Otherwise the 8254 will be used for timing services.
506f1d07 903
8f9ca475 904 Choose N to continue using the legacy 8254 timer.
506f1d07
SR
905
906config HPET_EMULATE_RTC
3c2362e6 907 def_bool y
3228e1dc 908 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
506f1d07 909
6a108a14 910# Mark as expert because too many people got it wrong.
506f1d07 911# The code disables itself when not needed.
7ae9392c
TP
912config DMI
913 default y
cf074402 914 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
6a108a14 915 bool "Enable DMI scanning" if EXPERT
a7f7f624 916 help
7ae9392c
TP
917 Enabled scanning of DMI to identify machine quirks. Say Y
918 here unless you have verified that your setup is not
919 affected by entries in the DMI blacklist. Required by PNP
920 BIOS code.
921
506f1d07 922config GART_IOMMU
38901f1c 923 bool "Old AMD GART IOMMU support"
2f9237d4 924 select DMA_OPS
a4ce5a48 925 select IOMMU_HELPER
506f1d07 926 select SWIOTLB
23ac4ae8 927 depends on X86_64 && PCI && AMD_NB
a7f7f624 928 help
ced3c42c
IM
929 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
930 GART based hardware IOMMUs.
931
932 The GART supports full DMA access for devices with 32-bit access
933 limitations, on systems with more than 3 GB. This is usually needed
934 for USB, sound, many IDE/SATA chipsets and some other devices.
935
936 Newer systems typically have a modern AMD IOMMU, supported via
937 the CONFIG_AMD_IOMMU=y config option.
938
939 In normal configurations this driver is only active when needed:
940 there's more than 3 GB of memory and the system contains a
941 32-bit limited device.
942
943 If unsure, say Y.
506f1d07 944
1184dc2f 945config MAXSMP
ddb0c5a6 946 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
6ea30386 947 depends on X86_64 && SMP && DEBUG_KERNEL
36f5101a 948 select CPUMASK_OFFSTACK
a7f7f624 949 help
ddb0c5a6 950 Enable maximum number of CPUS and NUMA Nodes for this architecture.
1184dc2f 951 If unsure, say N.
506f1d07 952
aec6487e
IM
953#
954# The maximum number of CPUs supported:
955#
956# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
957# and which can be configured interactively in the
958# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
959#
960# The ranges are different on 32-bit and 64-bit kernels, depending on
961# hardware capabilities and scalability features of the kernel.
962#
963# ( If MAXSMP is enabled we just use the highest possible value and disable
964# interactive configuration. )
965#
966
967config NR_CPUS_RANGE_BEGIN
a0d0bb4d 968 int
aec6487e
IM
969 default NR_CPUS_RANGE_END if MAXSMP
970 default 1 if !SMP
971 default 2
a0d0bb4d 972
aec6487e 973config NR_CPUS_RANGE_END
a0d0bb4d 974 int
aec6487e
IM
975 depends on X86_32
976 default 64 if SMP && X86_BIGSMP
977 default 8 if SMP && !X86_BIGSMP
978 default 1 if !SMP
a0d0bb4d 979
aec6487e 980config NR_CPUS_RANGE_END
a0d0bb4d 981 int
aec6487e 982 depends on X86_64
1edae1ae
SW
983 default 8192 if SMP && CPUMASK_OFFSTACK
984 default 512 if SMP && !CPUMASK_OFFSTACK
aec6487e 985 default 1 if !SMP
a0d0bb4d 986
aec6487e 987config NR_CPUS_DEFAULT
a0d0bb4d
RD
988 int
989 depends on X86_32
aec6487e
IM
990 default 32 if X86_BIGSMP
991 default 8 if SMP
992 default 1 if !SMP
a0d0bb4d 993
aec6487e 994config NR_CPUS_DEFAULT
a0d0bb4d
RD
995 int
996 depends on X86_64
aec6487e
IM
997 default 8192 if MAXSMP
998 default 64 if SMP
999 default 1 if !SMP
a0d0bb4d 1000
506f1d07 1001config NR_CPUS
36f5101a 1002 int "Maximum number of CPUs" if SMP && !MAXSMP
aec6487e
IM
1003 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1004 default NR_CPUS_DEFAULT
a7f7f624 1005 help
506f1d07 1006 This allows you to specify the maximum number of CPUs which this
bb61ccc7 1007 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
cad14bb9 1008 supported value is 8192, otherwise the maximum value is 512. The
506f1d07
SR
1009 minimum value which makes sense is 2.
1010
aec6487e
IM
1011 This is purely to save memory: each supported CPU adds about 8KB
1012 to the kernel image.
506f1d07 1013
66558b73
TC
1014config SCHED_CLUSTER
1015 bool "Cluster scheduler support"
1016 depends on SMP
1017 default y
1018 help
1019 Cluster scheduler support improves the CPU scheduler's decision
1020 making when dealing with machines that have clusters of CPUs.
1021 Cluster usually means a couple of CPUs which are placed closely
1022 by sharing mid-level caches, last-level cache tags or internal
1023 busses.
1024
506f1d07 1025config SCHED_SMT
dbe73364 1026 def_bool y if SMP
506f1d07
SR
1027
1028config SCHED_MC
3c2362e6
HH
1029 def_bool y
1030 prompt "Multi-core scheduler support"
c8e56d20 1031 depends on SMP
a7f7f624 1032 help
506f1d07
SR
1033 Multi-core scheduler support improves the CPU scheduler's decision
1034 making when dealing with multi-core CPU chips at a cost of slightly
1035 increased overhead in some places. If unsure say N here.
1036
de966cf4
TC
1037config SCHED_MC_PRIO
1038 bool "CPU core priorities scheduler support"
0a21fc12
IM
1039 depends on SCHED_MC && CPU_SUP_INTEL
1040 select X86_INTEL_PSTATE
1041 select CPU_FREQ
de966cf4 1042 default y
a7f7f624 1043 help
0a21fc12
IM
1044 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1045 core ordering determined at manufacturing time, which allows
1046 certain cores to reach higher turbo frequencies (when running
1047 single threaded workloads) than others.
de966cf4 1048
0a21fc12
IM
1049 Enabling this kernel feature teaches the scheduler about
1050 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1051 scheduler's CPU selection logic accordingly, so that higher
1052 overall system performance can be achieved.
de966cf4 1053
0a21fc12 1054 This feature will have no effect on CPUs without this feature.
de966cf4 1055
0a21fc12 1056 If unsure say Y here.
5e76b2ab 1057
30b8b006 1058config UP_LATE_INIT
b03b016f
KK
1059 def_bool y
1060 depends on !SMP && X86_LOCAL_APIC
30b8b006 1061
506f1d07 1062config X86_UP_APIC
50849eef
JB
1063 bool "Local APIC support on uniprocessors" if !PCI_MSI
1064 default PCI_MSI
38a1dfda 1065 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
a7f7f624 1066 help
506f1d07
SR
1067 A local APIC (Advanced Programmable Interrupt Controller) is an
1068 integrated interrupt controller in the CPU. If you have a single-CPU
1069 system which has a processor with a local APIC, you can say Y here to
1070 enable and use it. If you say Y here even though your machine doesn't
1071 have a local APIC, then the kernel will still run with no slowdown at
1072 all. The local APIC supports CPU-generated self-interrupts (timer,
1073 performance counters), and the NMI watchdog which detects hard
1074 lockups.
1075
1076config X86_UP_IOAPIC
1077 bool "IO-APIC support on uniprocessors"
1078 depends on X86_UP_APIC
a7f7f624 1079 help
506f1d07
SR
1080 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1081 SMP-capable replacement for PC-style interrupt controllers. Most
1082 SMP systems and many recent uniprocessor systems have one.
1083
1084 If you have a single-CPU system with an IO-APIC, you can say Y here
1085 to use it. If you say Y here even though your machine doesn't have
1086 an IO-APIC, then the kernel will still run with no slowdown at all.
1087
1088config X86_LOCAL_APIC
3c2362e6 1089 def_bool y
0dbc6078 1090 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
b5dc8e6c 1091 select IRQ_DOMAIN_HIERARCHY
52f518a3 1092 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
506f1d07
SR
1093
1094config X86_IO_APIC
b1da1e71
JB
1095 def_bool y
1096 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
506f1d07 1097
41b9eb26
SA
1098config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1099 bool "Reroute for broken boot IRQs"
41b9eb26 1100 depends on X86_IO_APIC
a7f7f624 1101 help
41b9eb26
SA
1102 This option enables a workaround that fixes a source of
1103 spurious interrupts. This is recommended when threaded
1104 interrupt handling is used on systems where the generation of
1105 superfluous "boot interrupts" cannot be disabled.
1106
1107 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1108 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1109 kernel does during interrupt handling). On chipsets where this
1110 boot IRQ generation cannot be disabled, this workaround keeps
1111 the original IRQ line masked so that only the equivalent "boot
1112 IRQ" is delivered to the CPUs. The workaround also tells the
1113 kernel to set up the IRQ handler on the boot IRQ line. In this
1114 way only one interrupt is delivered to the kernel. Otherwise
1115 the spurious second interrupt may cause the kernel to bring
1116 down (vital) interrupt lines.
1117
1118 Only affects "broken" chipsets. Interrupt sharing may be
1119 increased on these systems.
1120
506f1d07 1121config X86_MCE
bab9bc65 1122 bool "Machine Check / overheating reporting"
648ed940 1123 select GENERIC_ALLOCATOR
e57dbaf7 1124 default y
a7f7f624 1125 help
bab9bc65
AK
1126 Machine Check support allows the processor to notify the
1127 kernel if it detects a problem (e.g. overheating, data corruption).
506f1d07 1128 The action the kernel takes depends on the severity of the problem,
bab9bc65 1129 ranging from warning messages to halting the machine.
4efc0670 1130
5de97c9f
TL
1131config X86_MCELOG_LEGACY
1132 bool "Support for deprecated /dev/mcelog character device"
1133 depends on X86_MCE
a7f7f624 1134 help
5de97c9f
TL
1135 Enable support for /dev/mcelog which is needed by the old mcelog
1136 userspace logging daemon. Consider switching to the new generation
1137 rasdaemon solution.
1138
506f1d07 1139config X86_MCE_INTEL
3c2362e6
HH
1140 def_bool y
1141 prompt "Intel MCE features"
c1ebf835 1142 depends on X86_MCE && X86_LOCAL_APIC
a7f7f624 1143 help
506f1d07
SR
1144 Additional support for intel specific MCE features such as
1145 the thermal monitor.
1146
1147config X86_MCE_AMD
3c2362e6
HH
1148 def_bool y
1149 prompt "AMD MCE features"
f5382de9 1150 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
a7f7f624 1151 help
506f1d07
SR
1152 Additional support for AMD specific MCE features such as
1153 the DRAM Error Threshold.
1154
4efc0670 1155config X86_ANCIENT_MCE
6fc108a0 1156 bool "Support for old Pentium 5 / WinChip machine checks"
c31d9633 1157 depends on X86_32 && X86_MCE
a7f7f624 1158 help
cd13adcc 1159 Include support for machine check handling on old Pentium 5 or WinChip
5065a706 1160 systems. These typically need to be enabled explicitly on the command
cd13adcc 1161 line.
4efc0670 1162
b2762686
AK
1163config X86_MCE_THRESHOLD
1164 depends on X86_MCE_AMD || X86_MCE_INTEL
6fc108a0 1165 def_bool y
b2762686 1166
ea149b36 1167config X86_MCE_INJECT
bc8e80d5 1168 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
ea149b36 1169 tristate "Machine check injector support"
a7f7f624 1170 help
ea149b36
AK
1171 Provide support for injecting machine checks for testing purposes.
1172 If you don't know what a machine check is and you don't do kernel
1173 QA it is safe to say n.
1174
07dc900e 1175source "arch/x86/events/Kconfig"
e633c65a 1176
5aef51c3 1177config X86_LEGACY_VM86
1e642812 1178 bool "Legacy VM86 support"
506f1d07 1179 depends on X86_32
a7f7f624 1180 help
5aef51c3
AL
1181 This option allows user programs to put the CPU into V8086
1182 mode, which is an 80286-era approximation of 16-bit real mode.
1183
1184 Some very old versions of X and/or vbetool require this option
1185 for user mode setting. Similarly, DOSEMU will use it if
1186 available to accelerate real mode DOS programs. However, any
1187 recent version of DOSEMU, X, or vbetool should be fully
1188 functional even without kernel VM86 support, as they will all
1e642812
IM
1189 fall back to software emulation. Nevertheless, if you are using
1190 a 16-bit DOS program where 16-bit performance matters, vm86
1191 mode might be faster than emulation and you might want to
1192 enable this option.
5aef51c3 1193
1e642812
IM
1194 Note that any app that works on a 64-bit kernel is unlikely to
1195 need this option, as 64-bit kernels don't, and can't, support
1196 V8086 mode. This option is also unrelated to 16-bit protected
1197 mode and is not needed to run most 16-bit programs under Wine.
5aef51c3 1198
1e642812
IM
1199 Enabling this option increases the complexity of the kernel
1200 and slows down exception handling a tiny bit.
5aef51c3 1201
1e642812 1202 If unsure, say N here.
5aef51c3
AL
1203
1204config VM86
b03b016f
KK
1205 bool
1206 default X86_LEGACY_VM86
34273f41
PA
1207
1208config X86_16BIT
1209 bool "Enable support for 16-bit segments" if EXPERT
1210 default y
a5b9e5a2 1211 depends on MODIFY_LDT_SYSCALL
a7f7f624 1212 help
34273f41
PA
1213 This option is required by programs like Wine to run 16-bit
1214 protected mode legacy code on x86 processors. Disabling
1215 this option saves about 300 bytes on i386, or around 6K text
1216 plus 16K runtime memory on x86-64,
1217
1218config X86_ESPFIX32
1219 def_bool y
1220 depends on X86_16BIT && X86_32
506f1d07 1221
197725de
PA
1222config X86_ESPFIX64
1223 def_bool y
34273f41 1224 depends on X86_16BIT && X86_64
506f1d07 1225
1ad83c85 1226config X86_VSYSCALL_EMULATION
b03b016f
KK
1227 bool "Enable vsyscall emulation" if EXPERT
1228 default y
1229 depends on X86_64
a7f7f624 1230 help
1ad83c85
AL
1231 This enables emulation of the legacy vsyscall page. Disabling
1232 it is roughly equivalent to booting with vsyscall=none, except
1233 that it will also disable the helpful warning if a program
1234 tries to use a vsyscall. With this option set to N, offending
1235 programs will just segfault, citing addresses of the form
1236 0xffffffffff600?00.
1237
1238 This option is required by many programs built before 2013, and
1239 care should be used even with newer programs if set to N.
1240
1241 Disabling this option saves about 7K of kernel size and
1242 possibly 4K of additional runtime pagetable memory.
1243
111e7b15
TG
1244config X86_IOPL_IOPERM
1245 bool "IOPERM and IOPL Emulation"
a24ca997 1246 default y
a7f7f624 1247 help
111e7b15
TG
1248 This enables the ioperm() and iopl() syscalls which are necessary
1249 for legacy applications.
1250
c8137ace
TG
1251 Legacy IOPL support is an overbroad mechanism which allows user
1252 space aside of accessing all 65536 I/O ports also to disable
1253 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1254 capabilities and permission from potentially active security
1255 modules.
1256
1257 The emulation restricts the functionality of the syscall to
1258 only allowing the full range I/O port access, but prevents the
a24ca997
TG
1259 ability to disable interrupts from user space which would be
1260 granted if the hardware IOPL mechanism would be used.
c8137ace 1261
506f1d07
SR
1262config TOSHIBA
1263 tristate "Toshiba Laptop support"
1264 depends on X86_32
a7f7f624 1265 help
506f1d07
SR
1266 This adds a driver to safely access the System Management Mode of
1267 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1268 not work on models with a Phoenix BIOS. The System Management Mode
1269 is used to set the BIOS and power saving options on Toshiba portables.
1270
1271 For information on utilities to make use of this driver see the
1272 Toshiba Linux utilities web site at:
1273 <http://www.buzzard.org.uk/toshiba/>.
1274
1275 Say Y if you intend to run this kernel on a Toshiba portable.
1276 Say N otherwise.
1277
1278config I8K
039ae585 1279 tristate "Dell i8k legacy laptop support"
ef775a0e
RD
1280 depends on HWMON
1281 depends on PROC_FS
039ae585 1282 select SENSORS_DELL_SMM
a7f7f624 1283 help
039ae585
PR
1284 This option enables legacy /proc/i8k userspace interface in hwmon
1285 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1286 temperature and allows controlling fan speeds of Dell laptops via
1287 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1288 it reports also power and hotkey status. For fan speed control is
1289 needed userspace package i8kutils.
1290
1291 Say Y if you intend to run this kernel on old Dell laptops or want to
1292 use userspace package i8kutils.
506f1d07
SR
1293 Say N otherwise.
1294
1295config X86_REBOOTFIXUPS
9ba16087
JB
1296 bool "Enable X86 board specific fixups for reboot"
1297 depends on X86_32
a7f7f624 1298 help
506f1d07
SR
1299 This enables chipset and/or board specific fixups to be done
1300 in order to get reboot to work correctly. This is only needed on
1301 some combinations of hardware and BIOS. The symptom, for which
1302 this config is intended, is when reboot ends with a stalled/hung
1303 system.
1304
1305 Currently, the only fixup is for the Geode machines using
5e3a77e9 1306 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
506f1d07
SR
1307
1308 Say Y if you want to enable the fixup. Currently, it's safe to
1309 enable this option even if you don't need it.
1310 Say N otherwise.
1311
1312config MICROCODE
9a2bc335
BP
1313 bool "CPU microcode loading support"
1314 default y
80030e3d 1315 depends on CPU_SUP_AMD || CPU_SUP_INTEL
a7f7f624 1316 help
506f1d07 1317 If you say Y here, you will be able to update the microcode on
5f9c01aa
BP
1318 Intel and AMD processors. The Intel support is for the IA32 family,
1319 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1320 AMD support is for families 0x10 and later. You will obviously need
1321 the actual microcode binary data itself which is not shipped with
1322 the Linux kernel.
1323
1324 The preferred method to load microcode from a detached initrd is described
cb1aaebe 1325 in Documentation/x86/microcode.rst. For that you need to enable
5f9c01aa
BP
1326 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1327 initrd for microcode blobs.
1328
c508c46e
BG
1329 In addition, you can build the microcode into the kernel. For that you
1330 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1331 config option.
506f1d07 1332
8d86f390 1333config MICROCODE_INTEL
e43f6e67 1334 bool "Intel microcode loading support"
8f9ca475
IM
1335 depends on MICROCODE
1336 default MICROCODE
a7f7f624 1337 help
8f9ca475
IM
1338 This options enables microcode patch loading support for Intel
1339 processors.
1340
b8989db9
A
1341 For the current Intel microcode data package go to
1342 <https://downloadcenter.intel.com> and search for
1343 'Linux Processor Microcode Data File'.
8d86f390 1344
80cc9f10 1345config MICROCODE_AMD
e43f6e67 1346 bool "AMD microcode loading support"
8f9ca475 1347 depends on MICROCODE
a7f7f624 1348 help
8f9ca475
IM
1349 If you select this option, microcode patch loading support for AMD
1350 processors will be enabled.
80cc9f10 1351
8f9ca475 1352config MICROCODE_OLD_INTERFACE
c02f48e0
BP
1353 bool "Ancient loading interface (DEPRECATED)"
1354 default n
506f1d07 1355 depends on MICROCODE
a7f7f624 1356 help
c02f48e0
BP
1357 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1358 which was used by userspace tools like iucode_tool and microcode.ctl.
1359 It is inadequate because it runs too late to be able to properly
1360 load microcode on a machine and it needs special tools. Instead, you
1361 should've switched to the early loading method with the initrd or
cb1aaebe 1362 builtin microcode by now: Documentation/x86/microcode.rst
506f1d07
SR
1363
1364config X86_MSR
1365 tristate "/dev/cpu/*/msr - Model-specific register support"
a7f7f624 1366 help
506f1d07
SR
1367 This device gives privileged processes access to the x86
1368 Model-Specific Registers (MSRs). It is a character device with
1369 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1370 MSR accesses are directed to a specific CPU on multi-processor
1371 systems.
1372
1373config X86_CPUID
1374 tristate "/dev/cpu/*/cpuid - CPU information support"
a7f7f624 1375 help
506f1d07
SR
1376 This device gives processes access to the x86 CPUID instruction to
1377 be executed on a specific processor. It is a character device
1378 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1379 /dev/cpu/31/cpuid.
1380
1381choice
1382 prompt "High Memory Support"
6fc108a0 1383 default HIGHMEM4G
506f1d07
SR
1384 depends on X86_32
1385
1386config NOHIGHMEM
1387 bool "off"
a7f7f624 1388 help
506f1d07
SR
1389 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1390 However, the address space of 32-bit x86 processors is only 4
1391 Gigabytes large. That means that, if you have a large amount of
1392 physical memory, not all of it can be "permanently mapped" by the
1393 kernel. The physical memory that's not permanently mapped is called
1394 "high memory".
1395
1396 If you are compiling a kernel which will never run on a machine with
1397 more than 1 Gigabyte total physical RAM, answer "off" here (default
1398 choice and suitable for most users). This will result in a "3GB/1GB"
1399 split: 3GB are mapped so that each process sees a 3GB virtual memory
1400 space and the remaining part of the 4GB virtual memory space is used
1401 by the kernel to permanently map as much physical memory as
1402 possible.
1403
1404 If the machine has between 1 and 4 Gigabytes physical RAM, then
1405 answer "4GB" here.
1406
1407 If more than 4 Gigabytes is used then answer "64GB" here. This
1408 selection turns Intel PAE (Physical Address Extension) mode on.
1409 PAE implements 3-level paging on IA32 processors. PAE is fully
1410 supported by Linux, PAE mode is implemented on all recent Intel
1411 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1412 then the kernel will not boot on CPUs that don't support PAE!
1413
1414 The actual amount of total physical memory will either be
1415 auto detected or can be forced by using a kernel command line option
1416 such as "mem=256M". (Try "man bootparam" or see the documentation of
1417 your boot loader (lilo or loadlin) about how to pass options to the
1418 kernel at boot time.)
1419
1420 If unsure, say "off".
1421
1422config HIGHMEM4G
1423 bool "4GB"
a7f7f624 1424 help
506f1d07
SR
1425 Select this if you have a 32-bit processor and between 1 and 4
1426 gigabytes of physical RAM.
1427
1428config HIGHMEM64G
1429 bool "64GB"
225bac2d 1430 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
506f1d07 1431 select X86_PAE
a7f7f624 1432 help
506f1d07
SR
1433 Select this if you have a 32-bit processor and more than 4
1434 gigabytes of physical RAM.
1435
1436endchoice
1437
1438choice
6a108a14 1439 prompt "Memory split" if EXPERT
506f1d07
SR
1440 default VMSPLIT_3G
1441 depends on X86_32
a7f7f624 1442 help
506f1d07
SR
1443 Select the desired split between kernel and user memory.
1444
1445 If the address range available to the kernel is less than the
1446 physical memory installed, the remaining memory will be available
1447 as "high memory". Accessing high memory is a little more costly
1448 than low memory, as it needs to be mapped into the kernel first.
1449 Note that increasing the kernel address space limits the range
1450 available to user programs, making the address space there
1451 tighter. Selecting anything other than the default 3G/1G split
1452 will also likely make your kernel incompatible with binary-only
1453 kernel modules.
1454
1455 If you are not absolutely sure what you are doing, leave this
1456 option alone!
1457
1458 config VMSPLIT_3G
1459 bool "3G/1G user/kernel split"
1460 config VMSPLIT_3G_OPT
1461 depends on !X86_PAE
1462 bool "3G/1G user/kernel split (for full 1G low memory)"
1463 config VMSPLIT_2G
1464 bool "2G/2G user/kernel split"
1465 config VMSPLIT_2G_OPT
1466 depends on !X86_PAE
1467 bool "2G/2G user/kernel split (for full 2G low memory)"
1468 config VMSPLIT_1G
1469 bool "1G/3G user/kernel split"
1470endchoice
1471
1472config PAGE_OFFSET
1473 hex
1474 default 0xB0000000 if VMSPLIT_3G_OPT
1475 default 0x80000000 if VMSPLIT_2G
1476 default 0x78000000 if VMSPLIT_2G_OPT
1477 default 0x40000000 if VMSPLIT_1G
1478 default 0xC0000000
1479 depends on X86_32
1480
1481config HIGHMEM
3c2362e6 1482 def_bool y
506f1d07 1483 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
506f1d07
SR
1484
1485config X86_PAE
9ba16087 1486 bool "PAE (Physical Address Extension) Support"
506f1d07 1487 depends on X86_32 && !HIGHMEM4G
d4a451d5 1488 select PHYS_ADDR_T_64BIT
9d99c712 1489 select SWIOTLB
a7f7f624 1490 help
506f1d07
SR
1491 PAE is required for NX support, and furthermore enables
1492 larger swapspace support for non-overcommit purposes. It
1493 has the cost of more pagetable lookup overhead, and also
1494 consumes more pagetable space per process.
1495
77ef56e4
KS
1496config X86_5LEVEL
1497 bool "Enable 5-level page tables support"
18ec1eaf 1498 default y
eedb92ab 1499 select DYNAMIC_MEMORY_LAYOUT
162434e7 1500 select SPARSEMEM_VMEMMAP
77ef56e4 1501 depends on X86_64
a7f7f624 1502 help
77ef56e4
KS
1503 5-level paging enables access to larger address space:
1504 upto 128 PiB of virtual address space and 4 PiB of
1505 physical address space.
1506
1507 It will be supported by future Intel CPUs.
1508
6657fca0
KS
1509 A kernel with the option enabled can be booted on machines that
1510 support 4- or 5-level paging.
77ef56e4 1511
cb1aaebe 1512 See Documentation/x86/x86_64/5level-paging.rst for more
77ef56e4
KS
1513 information.
1514
1515 Say N if unsure.
1516
10971ab2 1517config X86_DIRECT_GBPAGES
e5008abe 1518 def_bool y
2e1da13f 1519 depends on X86_64
a7f7f624 1520 help
10971ab2
IM
1521 Certain kernel features effectively disable kernel
1522 linear 1 GB mappings (even if the CPU otherwise
1523 supports them), so don't confuse the user by printing
1524 that we have them enabled.
9e899816 1525
5c280cf6
TG
1526config X86_CPA_STATISTICS
1527 bool "Enable statistic for Change Page Attribute"
1528 depends on DEBUG_FS
a7f7f624 1529 help
b75baaf3 1530 Expose statistics about the Change Page Attribute mechanism, which
a943245a 1531 helps to determine the effectiveness of preserving large and huge
5c280cf6
TG
1532 page mappings when mapping protections are changed.
1533
20f07a04
KS
1534config X86_MEM_ENCRYPT
1535 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1536 select DYNAMIC_PHYSICAL_MASK
1537 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1538 def_bool n
1539
7744ccdb
TL
1540config AMD_MEM_ENCRYPT
1541 bool "AMD Secure Memory Encryption (SME) support"
1542 depends on X86_64 && CPU_SUP_AMD
82fef0ad 1543 select DMA_COHERENT_POOL
ce9084ba 1544 select ARCH_USE_MEMREMAP_PROT
597cfe48 1545 select INSTRUCTION_DECODER
aa5a4611 1546 select ARCH_HAS_CC_PLATFORM
20f07a04 1547 select X86_MEM_ENCRYPT
a7f7f624 1548 help
7744ccdb
TL
1549 Say yes to enable support for the encryption of system memory.
1550 This requires an AMD processor that supports Secure Memory
1551 Encryption (SME).
1552
1553config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1554 bool "Activate AMD Secure Memory Encryption (SME) by default"
7744ccdb 1555 depends on AMD_MEM_ENCRYPT
a7f7f624 1556 help
7744ccdb
TL
1557 Say yes to have system memory encrypted by default if running on
1558 an AMD processor that supports Secure Memory Encryption (SME).
1559
1560 If set to Y, then the encryption of system memory can be
1561 deactivated with the mem_encrypt=off command line option.
1562
1563 If set to N, then the encryption of system memory can be
1564 activated with the mem_encrypt=on command line option.
1565
506f1d07
SR
1566# Common NUMA Features
1567config NUMA
e133f6ea 1568 bool "NUMA Memory Allocation and Scheduler Support"
506f1d07 1569 depends on SMP
b5660ba7
PA
1570 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1571 default y if X86_BIGSMP
7ecd19cf 1572 select USE_PERCPU_NUMA_NODE_ID
a7f7f624 1573 help
e133f6ea 1574 Enable NUMA (Non-Uniform Memory Access) support.
fd51b2d7 1575
506f1d07
SR
1576 The kernel will try to allocate memory used by a CPU on the
1577 local memory controller of the CPU and add some more
1578 NUMA awareness to the kernel.
1579
c280ea5e 1580 For 64-bit this is recommended if the system is Intel Core i7
fd51b2d7
KM
1581 (or later), AMD Opteron, or EM64T NUMA.
1582
b5660ba7 1583 For 32-bit this is only needed if you boot a 32-bit
7cf6c945 1584 kernel on a 64-bit NUMA platform.
fd51b2d7
KM
1585
1586 Otherwise, you should say N.
506f1d07 1587
eec1d4fa 1588config AMD_NUMA
3c2362e6
HH
1589 def_bool y
1590 prompt "Old style AMD Opteron NUMA detection"
5da0ef9a 1591 depends on X86_64 && NUMA && PCI
a7f7f624 1592 help
eec1d4fa
HR
1593 Enable AMD NUMA node topology detection. You should say Y here if
1594 you have a multi processor AMD system. This uses an old method to
1595 read the NUMA configuration directly from the builtin Northbridge
1596 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1597 which also takes priority if both are compiled in.
506f1d07
SR
1598
1599config X86_64_ACPI_NUMA
3c2362e6
HH
1600 def_bool y
1601 prompt "ACPI NUMA detection"
506f1d07
SR
1602 depends on X86_64 && NUMA && ACPI && PCI
1603 select ACPI_NUMA
a7f7f624 1604 help
506f1d07
SR
1605 Enable ACPI SRAT based node topology detection.
1606
1607config NUMA_EMU
1608 bool "NUMA emulation"
1b7e03ef 1609 depends on NUMA
a7f7f624 1610 help
506f1d07
SR
1611 Enable NUMA emulation. A flat machine will be split
1612 into virtual nodes when booted with "numa=fake=N", where N is the
1613 number of nodes. This is only useful for debugging.
1614
1615config NODES_SHIFT
d25e26b6 1616 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
51591e31
DR
1617 range 1 10
1618 default "10" if MAXSMP
506f1d07 1619 default "6" if X86_64
506f1d07 1620 default "3"
a9ee6cf5 1621 depends on NUMA
a7f7f624 1622 help
1184dc2f 1623 Specify the maximum number of NUMA Nodes available on the target
692105b8 1624 system. Increases memory reserved to accommodate various tables.
506f1d07 1625
506f1d07
SR
1626config ARCH_FLATMEM_ENABLE
1627 def_bool y
3b16651f 1628 depends on X86_32 && !NUMA
506f1d07 1629
506f1d07
SR
1630config ARCH_SPARSEMEM_ENABLE
1631 def_bool y
6ea30386 1632 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
506f1d07
SR
1633 select SPARSEMEM_STATIC if X86_32
1634 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1635
3b16651f 1636config ARCH_SPARSEMEM_DEFAULT
6ad57f7f 1637 def_bool X86_64 || (NUMA && X86_32)
3b16651f 1638
506f1d07
SR
1639config ARCH_SELECT_MEMORY_MODEL
1640 def_bool y
b263295d 1641 depends on ARCH_SPARSEMEM_ENABLE
506f1d07
SR
1642
1643config ARCH_MEMORY_PROBE
a0842b70 1644 bool "Enable sysfs memory/probe interface"
5c11f00b 1645 depends on MEMORY_HOTPLUG
a0842b70
TK
1646 help
1647 This option enables a sysfs memory/probe interface for testing.
cb1aaebe 1648 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
a0842b70 1649 If you are unsure how to answer this question, answer N.
506f1d07 1650
3b16651f
TH
1651config ARCH_PROC_KCORE_TEXT
1652 def_bool y
1653 depends on X86_64 && PROC_KCORE
1654
a29815a3 1655config ILLEGAL_POINTER_VALUE
b03b016f
KK
1656 hex
1657 default 0 if X86_32
1658 default 0xdead000000000000 if X86_64
a29815a3 1659
7a67832c
DW
1660config X86_PMEM_LEGACY_DEVICE
1661 bool
1662
ec776ef6 1663config X86_PMEM_LEGACY
7a67832c 1664 tristate "Support non-standard NVDIMMs and ADR protected memory"
9f53f9fa
DW
1665 depends on PHYS_ADDR_T_64BIT
1666 depends on BLK_DEV
7a67832c 1667 select X86_PMEM_LEGACY_DEVICE
7b27a862 1668 select NUMA_KEEP_MEMINFO if NUMA
9f53f9fa 1669 select LIBNVDIMM
ec776ef6
CH
1670 help
1671 Treat memory marked using the non-standard e820 type of 12 as used
1672 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1673 The kernel will offer these regions to the 'pmem' driver so
1674 they can be used for persistent storage.
1675
1676 Say Y if unsure.
1677
506f1d07
SR
1678config HIGHPTE
1679 bool "Allocate 3rd-level pagetables from highmem"
6fc108a0 1680 depends on HIGHMEM
a7f7f624 1681 help
506f1d07
SR
1682 The VM uses one page table entry for each page of physical memory.
1683 For systems with a lot of RAM, this can be wasteful of precious
1684 low memory. Setting this option will put user-space page table
1685 entries in high memory.
1686
9f077871 1687config X86_CHECK_BIOS_CORRUPTION
8f9ca475 1688 bool "Check for low memory corruption"
a7f7f624 1689 help
8f9ca475
IM
1690 Periodically check for memory corruption in low memory, which
1691 is suspected to be caused by BIOS. Even when enabled in the
1692 configuration, it is disabled at runtime. Enable it by
1693 setting "memory_corruption_check=1" on the kernel command
1694 line. By default it scans the low 64k of memory every 60
1695 seconds; see the memory_corruption_check_size and
1696 memory_corruption_check_period parameters in
8c27ceff 1697 Documentation/admin-guide/kernel-parameters.rst to adjust this.
8f9ca475
IM
1698
1699 When enabled with the default parameters, this option has
1700 almost no overhead, as it reserves a relatively small amount
1701 of memory and scans it infrequently. It both detects corruption
1702 and prevents it from affecting the running system.
1703
1704 It is, however, intended as a diagnostic tool; if repeatable
1705 BIOS-originated corruption always affects the same memory,
1706 you can use memmap= to prevent the kernel from using that
1707 memory.
9f077871 1708
c885df50 1709config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
8f9ca475 1710 bool "Set the default setting of memory_corruption_check"
c885df50
JF
1711 depends on X86_CHECK_BIOS_CORRUPTION
1712 default y
a7f7f624 1713 help
8f9ca475
IM
1714 Set whether the default state of memory_corruption_check is
1715 on or off.
c885df50 1716
506f1d07
SR
1717config MATH_EMULATION
1718 bool
a5b9e5a2 1719 depends on MODIFY_LDT_SYSCALL
87d6021b 1720 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
a7f7f624 1721 help
506f1d07
SR
1722 Linux can emulate a math coprocessor (used for floating point
1723 operations) if you don't have one. 486DX and Pentium processors have
1724 a math coprocessor built in, 486SX and 386 do not, unless you added
1725 a 487DX or 387, respectively. (The messages during boot time can
1726 give you some hints here ["man dmesg"].) Everyone needs either a
1727 coprocessor or this emulation.
1728
1729 If you don't have a math coprocessor, you need to say Y here; if you
1730 say Y here even though you have a coprocessor, the coprocessor will
1731 be used nevertheless. (This behavior can be changed with the kernel
1732 command line option "no387", which comes handy if your coprocessor
1733 is broken. Try "man bootparam" or see the documentation of your boot
1734 loader (lilo or loadlin) about how to pass options to the kernel at
1735 boot time.) This means that it is a good idea to say Y here if you
1736 intend to use this kernel on different machines.
1737
1738 More information about the internals of the Linux math coprocessor
1739 emulation can be found in <file:arch/x86/math-emu/README>.
1740
1741 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1742 kernel, it won't hurt.
1743
1744config MTRR
6fc108a0 1745 def_bool y
6a108a14 1746 prompt "MTRR (Memory Type Range Register) support" if EXPERT
a7f7f624 1747 help
506f1d07
SR
1748 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1749 the Memory Type Range Registers (MTRRs) may be used to control
1750 processor access to memory ranges. This is most useful if you have
1751 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1752 allows bus write transfers to be combined into a larger transfer
1753 before bursting over the PCI/AGP bus. This can increase performance
1754 of image write operations 2.5 times or more. Saying Y here creates a
1755 /proc/mtrr file which may be used to manipulate your processor's
1756 MTRRs. Typically the X server should use this.
1757
1758 This code has a reasonably generic interface so that similar
1759 control registers on other processors can be easily supported
1760 as well:
1761
1762 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1763 Registers (ARRs) which provide a similar functionality to MTRRs. For
1764 these, the ARRs are used to emulate the MTRRs.
1765 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1766 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1767 write-combining. All of these processors are supported by this code
1768 and it makes sense to say Y here if you have one of them.
1769
1770 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1771 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1772 can lead to all sorts of problems, so it's good to say Y here.
1773
1774 You can safely say Y even if your machine doesn't have MTRRs, you'll
1775 just add about 9 KB to your kernel.
1776
cb1aaebe 1777 See <file:Documentation/x86/mtrr.rst> for more information.
506f1d07 1778
95ffa243 1779config MTRR_SANITIZER
2ffb3501 1780 def_bool y
95ffa243
YL
1781 prompt "MTRR cleanup support"
1782 depends on MTRR
a7f7f624 1783 help
aba3728c
TG
1784 Convert MTRR layout from continuous to discrete, so X drivers can
1785 add writeback entries.
95ffa243 1786
aba3728c 1787 Can be disabled with disable_mtrr_cleanup on the kernel command line.
692105b8 1788 The largest mtrr entry size for a continuous block can be set with
aba3728c 1789 mtrr_chunk_size.
95ffa243 1790
2ffb3501 1791 If unsure, say Y.
95ffa243
YL
1792
1793config MTRR_SANITIZER_ENABLE_DEFAULT
f5098d62
YL
1794 int "MTRR cleanup enable value (0-1)"
1795 range 0 1
1796 default "0"
95ffa243 1797 depends on MTRR_SANITIZER
a7f7f624 1798 help
f5098d62 1799 Enable mtrr cleanup default value
95ffa243 1800
12031a62
YL
1801config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1802 int "MTRR cleanup spare reg num (0-7)"
1803 range 0 7
1804 default "1"
1805 depends on MTRR_SANITIZER
a7f7f624 1806 help
12031a62 1807 mtrr cleanup spare entries default, it can be changed via
aba3728c 1808 mtrr_spare_reg_nr=N on the kernel command line.
12031a62 1809
2e5d9c85 1810config X86_PAT
6fc108a0 1811 def_bool y
6a108a14 1812 prompt "x86 PAT support" if EXPERT
2a8a2719 1813 depends on MTRR
a7f7f624 1814 help
2e5d9c85 1815 Use PAT attributes to setup page level cache control.
042b78e4 1816
2e5d9c85 1817 PATs are the modern equivalents of MTRRs and are much more
1818 flexible than MTRRs.
1819
1820 Say N here if you see bootup problems (boot crash, boot hang,
042b78e4 1821 spontaneous reboots) or a non-working video driver.
2e5d9c85 1822
1823 If unsure, say Y.
1824
46cf98cd
VP
1825config ARCH_USES_PG_UNCACHED
1826 def_bool y
1827 depends on X86_PAT
1828
628c6246
PA
1829config ARCH_RANDOM
1830 def_bool y
1831 prompt "x86 architectural random number generator" if EXPERT
a7f7f624 1832 help
628c6246
PA
1833 Enable the x86 architectural RDRAND instruction
1834 (Intel Bull Mountain technology) to generate random numbers.
1835 If supported, this is a high bandwidth, cryptographically
1836 secure hardware random number generator.
1837
51ae4a2d
PA
1838config X86_SMAP
1839 def_bool y
1840 prompt "Supervisor Mode Access Prevention" if EXPERT
a7f7f624 1841 help
51ae4a2d
PA
1842 Supervisor Mode Access Prevention (SMAP) is a security
1843 feature in newer Intel processors. There is a small
1844 performance cost if this enabled and turned on; there is
1845 also a small increase in the kernel size if this is enabled.
1846
1847 If unsure, say Y.
1848
b971880f 1849config X86_UMIP
796ebc81 1850 def_bool y
b971880f 1851 prompt "User Mode Instruction Prevention" if EXPERT
a7f7f624 1852 help
b971880f
BM
1853 User Mode Instruction Prevention (UMIP) is a security feature in
1854 some x86 processors. If enabled, a general protection fault is
1855 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1856 executed in user mode. These instructions unnecessarily expose
1857 information about the hardware state.
796ebc81
RN
1858
1859 The vast majority of applications do not use these instructions.
1860 For the very few that do, software emulation is provided in
1861 specific cases in protected and virtual-8086 modes. Emulated
1862 results are dummy.
aa35f896 1863
156ff4a5
PZ
1864config CC_HAS_IBT
1865 # GCC >= 9 and binutils >= 2.29
1866 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
1867 # Clang/LLVM >= 14
1868 # fentry check to work around https://reviews.llvm.org/D111108
1869 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
1870 (CC_IS_CLANG && $(success,echo "void a(void) {}" | $(CC) -Werror $(CLANG_FLAGS) -fcf-protection=branch -mfentry -pg -x c - -c -o /dev/null))) && \
1871 $(as-instr,endbr64)
1872
1873config X86_KERNEL_IBT
1874 prompt "Indirect Branch Tracking"
1875 bool
1876 depends on X86_64 && CC_HAS_IBT
1877 help
1878 Build the kernel with support for Indirect Branch Tracking, a
1879 hardware support course-grain forward-edge Control Flow Integrity
1880 protection. It enforces that all indirect calls must land on
1881 an ENDBR instruction, as such, the compiler will instrument the
1882 code with them to make this happen.
1883
35e97790 1884config X86_INTEL_MEMORY_PROTECTION_KEYS
38f3e775 1885 prompt "Memory Protection Keys"
35e97790 1886 def_bool y
284244a9 1887 # Note: only available in 64-bit mode
38f3e775 1888 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
52c8e601
IM
1889 select ARCH_USES_HIGH_VMA_FLAGS
1890 select ARCH_HAS_PKEYS
a7f7f624 1891 help
284244a9
DH
1892 Memory Protection Keys provides a mechanism for enforcing
1893 page-based protections, but without requiring modification of the
1894 page tables when an application changes protection domains.
1895
1eecbcdc 1896 For details, see Documentation/core-api/protection-keys.rst
284244a9
DH
1897
1898 If unsure, say y.
35e97790 1899
db616173
MH
1900choice
1901 prompt "TSX enable mode"
1902 depends on CPU_SUP_INTEL
1903 default X86_INTEL_TSX_MODE_OFF
1904 help
1905 Intel's TSX (Transactional Synchronization Extensions) feature
1906 allows to optimize locking protocols through lock elision which
1907 can lead to a noticeable performance boost.
1908
1909 On the other hand it has been shown that TSX can be exploited
1910 to form side channel attacks (e.g. TAA) and chances are there
1911 will be more of those attacks discovered in the future.
1912
1913 Therefore TSX is not enabled by default (aka tsx=off). An admin
1914 might override this decision by tsx=on the command line parameter.
1915 Even with TSX enabled, the kernel will attempt to enable the best
1916 possible TAA mitigation setting depending on the microcode available
1917 for the particular machine.
1918
1919 This option allows to set the default tsx mode between tsx=on, =off
1920 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1921 details.
1922
1923 Say off if not sure, auto if TSX is in use but it should be used on safe
1924 platforms or on if TSX is in use and the security aspect of tsx is not
1925 relevant.
1926
1927config X86_INTEL_TSX_MODE_OFF
1928 bool "off"
1929 help
1930 TSX is disabled if possible - equals to tsx=off command line parameter.
1931
1932config X86_INTEL_TSX_MODE_ON
1933 bool "on"
1934 help
1935 TSX is always enabled on TSX capable HW - equals the tsx=on command
1936 line parameter.
1937
1938config X86_INTEL_TSX_MODE_AUTO
1939 bool "auto"
1940 help
1941 TSX is enabled on TSX capable HW that is believed to be safe against
1942 side channel attacks- equals the tsx=auto command line parameter.
1943endchoice
1944
e7e05452
SC
1945config X86_SGX
1946 bool "Software Guard eXtensions (SGX)"
1947 depends on X86_64 && CPU_SUP_INTEL
1948 depends on CRYPTO=y
1949 depends on CRYPTO_SHA256=y
1950 select SRCU
1951 select MMU_NOTIFIER
901ddbb9 1952 select NUMA_KEEP_MEMINFO if NUMA
40e0e784 1953 select XARRAY_MULTI
e7e05452
SC
1954 help
1955 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1956 that can be used by applications to set aside private regions of code
1957 and data, referred to as enclaves. An enclave's private memory can
1958 only be accessed by code running within the enclave. Accesses from
1959 outside the enclave, including other enclaves, are disallowed by
1960 hardware.
1961
1962 If unsure, say N.
1963
506f1d07 1964config EFI
9ba16087 1965 bool "EFI runtime service support"
5b83683f 1966 depends on ACPI
f6ce5002 1967 select UCS2_STRING
022ee6c5 1968 select EFI_RUNTIME_WRAPPERS
1ff2fc02 1969 select ARCH_USE_MEMREMAP_PROT
a7f7f624 1970 help
8f9ca475
IM
1971 This enables the kernel to use EFI runtime services that are
1972 available (such as the EFI variable services).
506f1d07 1973
8f9ca475
IM
1974 This option is only useful on systems that have EFI firmware.
1975 In addition, you should use the latest ELILO loader available
1976 at <http://elilo.sourceforge.net> in order to take advantage
1977 of EFI runtime services. However, even with this option, the
1978 resultant kernel should continue to boot on existing non-EFI
1979 platforms.
506f1d07 1980
291f3632 1981config EFI_STUB
8f24f8c2 1982 bool "EFI stub support"
c6dbd3e5 1983 depends on EFI
8f24f8c2
AB
1984 depends on $(cc-option,-mabi=ms) || X86_32
1985 select RELOCATABLE
a7f7f624 1986 help
8f24f8c2 1987 This kernel feature allows a bzImage to be loaded directly
291f3632
MF
1988 by EFI firmware without the use of a bootloader.
1989
4f4cfa6c 1990 See Documentation/admin-guide/efi-stub.rst for more information.
0c759662 1991
7d453eee
MF
1992config EFI_MIXED
1993 bool "EFI mixed-mode support"
1994 depends on EFI_STUB && X86_64
a7f7f624 1995 help
7d453eee
MF
1996 Enabling this feature allows a 64-bit kernel to be booted
1997 on a 32-bit firmware, provided that your CPU supports 64-bit
1998 mode.
1999
2000 Note that it is not possible to boot a mixed-mode enabled
2001 kernel via the EFI boot stub - a bootloader that supports
2002 the EFI handover protocol must be used.
2003
2004 If unsure, say N.
2005
8636a1f9 2006source "kernel/Kconfig.hz"
506f1d07
SR
2007
2008config KEXEC
2009 bool "kexec system call"
2965faa5 2010 select KEXEC_CORE
a7f7f624 2011 help
506f1d07
SR
2012 kexec is a system call that implements the ability to shutdown your
2013 current kernel, and to start another kernel. It is like a reboot
2014 but it is independent of the system firmware. And like a reboot
2015 you can start any kernel with it, not just Linux.
2016
2017 The name comes from the similarity to the exec system call.
2018
2019 It is an ongoing process to be certain the hardware in a machine
2020 is properly shutdown, so do not be surprised if this code does not
bf220695
GU
2021 initially work for you. As of this writing the exact hardware
2022 interface is strongly in flux, so no good recommendation can be
2023 made.
506f1d07 2024
74ca317c
VG
2025config KEXEC_FILE
2026 bool "kexec file based system call"
2965faa5 2027 select KEXEC_CORE
74ca317c 2028 select BUILD_BIN2C
74ca317c
VG
2029 depends on X86_64
2030 depends on CRYPTO=y
2031 depends on CRYPTO_SHA256=y
a7f7f624 2032 help
74ca317c
VG
2033 This is new version of kexec system call. This system call is
2034 file based and takes file descriptors as system call argument
2035 for kernel and initramfs as opposed to list of segments as
2036 accepted by previous system call.
2037
b799a09f
AT
2038config ARCH_HAS_KEXEC_PURGATORY
2039 def_bool KEXEC_FILE
2040
99d5cadf 2041config KEXEC_SIG
8e7d8381 2042 bool "Verify kernel signature during kexec_file_load() syscall"
74ca317c 2043 depends on KEXEC_FILE
a7f7f624 2044 help
d8eb8940 2045
99d5cadf
JB
2046 This option makes the kexec_file_load() syscall check for a valid
2047 signature of the kernel image. The image can still be loaded without
2048 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2049 there's a signature that we can check, then it must be valid.
2050
2051 In addition to this option, you need to enable signature
d8eb8940
BP
2052 verification for the corresponding kernel image type being
2053 loaded in order for this to work.
8e7d8381 2054
99d5cadf
JB
2055config KEXEC_SIG_FORCE
2056 bool "Require a valid signature in kexec_file_load() syscall"
2057 depends on KEXEC_SIG
a7f7f624 2058 help
99d5cadf
JB
2059 This option makes kernel signature verification mandatory for
2060 the kexec_file_load() syscall.
2061
8e7d8381
VG
2062config KEXEC_BZIMAGE_VERIFY_SIG
2063 bool "Enable bzImage signature verification support"
99d5cadf 2064 depends on KEXEC_SIG
8e7d8381
VG
2065 depends on SIGNED_PE_FILE_VERIFICATION
2066 select SYSTEM_TRUSTED_KEYRING
a7f7f624 2067 help
8e7d8381
VG
2068 Enable bzImage signature verification support.
2069
506f1d07 2070config CRASH_DUMP
04b69447 2071 bool "kernel crash dumps"
506f1d07 2072 depends on X86_64 || (X86_32 && HIGHMEM)
a7f7f624 2073 help
506f1d07
SR
2074 Generate crash dump after being started by kexec.
2075 This should be normally only set in special crash dump kernels
2076 which are loaded in the main kernel with kexec-tools into
2077 a specially reserved region and then later executed after
2078 a crash by kdump/kexec. The crash dump kernel must be compiled
2079 to a memory address not used by the main kernel or BIOS using
2080 PHYSICAL_START, or it must be built as a relocatable image
2081 (CONFIG_RELOCATABLE=y).
330d4810 2082 For more details see Documentation/admin-guide/kdump/kdump.rst
506f1d07 2083
3ab83521 2084config KEXEC_JUMP
6ea30386 2085 bool "kexec jump"
fee7b0d8 2086 depends on KEXEC && HIBERNATION
a7f7f624 2087 help
89081d17
HY
2088 Jump between original kernel and kexeced kernel and invoke
2089 code in physical address mode via KEXEC
3ab83521 2090
506f1d07 2091config PHYSICAL_START
6a108a14 2092 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
ceefccc9 2093 default "0x1000000"
a7f7f624 2094 help
506f1d07
SR
2095 This gives the physical address where the kernel is loaded.
2096
2097 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2098 bzImage will decompress itself to above physical address and
2099 run from there. Otherwise, bzImage will run from the address where
2100 it has been loaded by the boot loader and will ignore above physical
2101 address.
2102
2103 In normal kdump cases one does not have to set/change this option
2104 as now bzImage can be compiled as a completely relocatable image
2105 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2106 address. This option is mainly useful for the folks who don't want
2107 to use a bzImage for capturing the crash dump and want to use a
2108 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2109 to be specifically compiled to run from a specific memory area
2110 (normally a reserved region) and this option comes handy.
2111
ceefccc9
PA
2112 So if you are using bzImage for capturing the crash dump,
2113 leave the value here unchanged to 0x1000000 and set
2114 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2115 for capturing the crash dump change this value to start of
2116 the reserved region. In other words, it can be set based on
2117 the "X" value as specified in the "crashkernel=YM@XM"
2118 command line boot parameter passed to the panic-ed
330d4810 2119 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
ceefccc9 2120 for more details about crash dumps.
506f1d07
SR
2121
2122 Usage of bzImage for capturing the crash dump is recommended as
2123 one does not have to build two kernels. Same kernel can be used
2124 as production kernel and capture kernel. Above option should have
2125 gone away after relocatable bzImage support is introduced. But it
2126 is present because there are users out there who continue to use
2127 vmlinux for dump capture. This option should go away down the
2128 line.
2129
2130 Don't change this unless you know what you are doing.
2131
2132config RELOCATABLE
26717808
PA
2133 bool "Build a relocatable kernel"
2134 default y
a7f7f624 2135 help
506f1d07
SR
2136 This builds a kernel image that retains relocation information
2137 so it can be loaded someplace besides the default 1MB.
2138 The relocations tend to make the kernel binary about 10% larger,
2139 but are discarded at runtime.
2140
2141 One use is for the kexec on panic case where the recovery kernel
2142 must live at a different physical address than the primary
2143 kernel.
2144
2145 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2146 it has been loaded at and the compile time physical address
8ab3820f 2147 (CONFIG_PHYSICAL_START) is used as the minimum location.
506f1d07 2148
8ab3820f 2149config RANDOMIZE_BASE
e8581e3d 2150 bool "Randomize the address of the kernel image (KASLR)"
8ab3820f 2151 depends on RELOCATABLE
6807c846 2152 default y
a7f7f624 2153 help
e8581e3d
BH
2154 In support of Kernel Address Space Layout Randomization (KASLR),
2155 this randomizes the physical address at which the kernel image
2156 is decompressed and the virtual address where the kernel
2157 image is mapped, as a security feature that deters exploit
2158 attempts relying on knowledge of the location of kernel
2159 code internals.
2160
ed9f007e
KC
2161 On 64-bit, the kernel physical and virtual addresses are
2162 randomized separately. The physical address will be anywhere
2163 between 16MB and the top of physical memory (up to 64TB). The
2164 virtual address will be randomized from 16MB up to 1GB (9 bits
2165 of entropy). Note that this also reduces the memory space
2166 available to kernel modules from 1.5GB to 1GB.
2167
2168 On 32-bit, the kernel physical and virtual addresses are
2169 randomized together. They will be randomized from 16MB up to
2170 512MB (8 bits of entropy).
e8581e3d
BH
2171
2172 Entropy is generated using the RDRAND instruction if it is
2173 supported. If RDTSC is supported, its value is mixed into
2174 the entropy pool as well. If neither RDRAND nor RDTSC are
ed9f007e
KC
2175 supported, then entropy is read from the i8254 timer. The
2176 usable entropy is limited by the kernel being built using
2177 2GB addressing, and that PHYSICAL_ALIGN must be at a
2178 minimum of 2MB. As a result, only 10 bits of entropy are
2179 theoretically possible, but the implementations are further
2180 limited due to memory layouts.
e8581e3d 2181
6807c846 2182 If unsure, say Y.
8ab3820f
KC
2183
2184# Relocation on x86 needs some additional build support
845adf72
PA
2185config X86_NEED_RELOCS
2186 def_bool y
8ab3820f 2187 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
845adf72 2188
506f1d07 2189config PHYSICAL_ALIGN
a0215061 2190 hex "Alignment value to which kernel should be aligned"
8ab3820f 2191 default "0x200000"
a0215061
KC
2192 range 0x2000 0x1000000 if X86_32
2193 range 0x200000 0x1000000 if X86_64
a7f7f624 2194 help
506f1d07
SR
2195 This value puts the alignment restrictions on physical address
2196 where kernel is loaded and run from. Kernel is compiled for an
2197 address which meets above alignment restriction.
2198
2199 If bootloader loads the kernel at a non-aligned address and
2200 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2201 address aligned to above value and run from there.
2202
2203 If bootloader loads the kernel at a non-aligned address and
2204 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2205 load address and decompress itself to the address it has been
2206 compiled for and run from there. The address for which kernel is
2207 compiled already meets above alignment restrictions. Hence the
2208 end result is that kernel runs from a physical address meeting
2209 above alignment restrictions.
2210
a0215061
KC
2211 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2212 this value must be a multiple of 0x200000.
2213
506f1d07
SR
2214 Don't change this unless you know what you are doing.
2215
eedb92ab
KS
2216config DYNAMIC_MEMORY_LAYOUT
2217 bool
a7f7f624 2218 help
eedb92ab
KS
2219 This option makes base addresses of vmalloc and vmemmap as well as
2220 __PAGE_OFFSET movable during boot.
2221
0483e1fa
TG
2222config RANDOMIZE_MEMORY
2223 bool "Randomize the kernel memory sections"
2224 depends on X86_64
2225 depends on RANDOMIZE_BASE
eedb92ab 2226 select DYNAMIC_MEMORY_LAYOUT
0483e1fa 2227 default RANDOMIZE_BASE
a7f7f624 2228 help
0483e1fa
TG
2229 Randomizes the base virtual address of kernel memory sections
2230 (physical memory mapping, vmalloc & vmemmap). This security feature
2231 makes exploits relying on predictable memory locations less reliable.
2232
2233 The order of allocations remains unchanged. Entropy is generated in
2234 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2235 configuration have in average 30,000 different possible virtual
2236 addresses for each memory section.
2237
6807c846 2238 If unsure, say Y.
0483e1fa 2239
90397a41
TG
2240config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2241 hex "Physical memory mapping padding" if EXPERT
2242 depends on RANDOMIZE_MEMORY
2243 default "0xa" if MEMORY_HOTPLUG
2244 default "0x0"
2245 range 0x1 0x40 if MEMORY_HOTPLUG
2246 range 0x0 0x40
a7f7f624 2247 help
90397a41
TG
2248 Define the padding in terabytes added to the existing physical
2249 memory size during kernel memory randomization. It is useful
2250 for memory hotplug support but reduces the entropy available for
2251 address randomization.
2252
2253 If unsure, leave at the default value.
2254
506f1d07 2255config HOTPLUG_CPU
bebd024e 2256 def_bool y
40b31360 2257 depends on SMP
506f1d07 2258
80aa1dff
FY
2259config BOOTPARAM_HOTPLUG_CPU0
2260 bool "Set default setting of cpu0_hotpluggable"
2c922cd0 2261 depends on HOTPLUG_CPU
a7f7f624 2262 help
80aa1dff
FY
2263 Set whether default state of cpu0_hotpluggable is on or off.
2264
2265 Say Y here to enable CPU0 hotplug by default. If this switch
2266 is turned on, there is no need to give cpu0_hotplug kernel
2267 parameter and the CPU0 hotplug feature is enabled by default.
2268
2269 Please note: there are two known CPU0 dependencies if you want
2270 to enable the CPU0 hotplug feature either by this switch or by
2271 cpu0_hotplug kernel parameter.
2272
2273 First, resume from hibernate or suspend always starts from CPU0.
2274 So hibernate and suspend are prevented if CPU0 is offline.
2275
2276 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2277 offline if any interrupt can not migrate out of CPU0. There may
2278 be other CPU0 dependencies.
2279
2280 Please make sure the dependencies are under your control before
2281 you enable this feature.
2282
2283 Say N if you don't want to enable CPU0 hotplug feature by default.
2284 You still can enable the CPU0 hotplug feature at boot by kernel
2285 parameter cpu0_hotplug.
2286
a71c8bc5
FY
2287config DEBUG_HOTPLUG_CPU0
2288 def_bool n
2289 prompt "Debug CPU0 hotplug"
2c922cd0 2290 depends on HOTPLUG_CPU
a7f7f624 2291 help
a71c8bc5
FY
2292 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2293 soon as possible and boots up userspace with CPU0 offlined. User
2294 can online CPU0 back after boot time.
2295
2296 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2297 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2298 compilation or giving cpu0_hotplug kernel parameter at boot.
2299
2300 If unsure, say N.
2301
506f1d07 2302config COMPAT_VDSO
b0b49f26
AL
2303 def_bool n
2304 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
953fee1d 2305 depends on COMPAT_32
a7f7f624 2306 help
b0b49f26
AL
2307 Certain buggy versions of glibc will crash if they are
2308 presented with a 32-bit vDSO that is not mapped at the address
2309 indicated in its segment table.
e84446de 2310
b0b49f26
AL
2311 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2312 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2313 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2314 the only released version with the bug, but OpenSUSE 9
2315 contains a buggy "glibc 2.3.2".
506f1d07 2316
b0b49f26
AL
2317 The symptom of the bug is that everything crashes on startup, saying:
2318 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2319
2320 Saying Y here changes the default value of the vdso32 boot
2321 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2322 This works around the glibc bug but hurts performance.
2323
2324 If unsure, say N: if you are compiling your own kernel, you
2325 are unlikely to be using a buggy version of glibc.
506f1d07 2326
3dc33bd3
KC
2327choice
2328 prompt "vsyscall table for legacy applications"
2329 depends on X86_64
625b7b7f 2330 default LEGACY_VSYSCALL_XONLY
3dc33bd3
KC
2331 help
2332 Legacy user code that does not know how to find the vDSO expects
2333 to be able to issue three syscalls by calling fixed addresses in
2334 kernel space. Since this location is not randomized with ASLR,
2335 it can be used to assist security vulnerability exploitation.
2336
2337 This setting can be changed at boot time via the kernel command
bd49e16e 2338 line parameter vsyscall=[emulate|xonly|none].
3dc33bd3
KC
2339
2340 On a system with recent enough glibc (2.14 or newer) and no
2341 static binaries, you can say None without a performance penalty
2342 to improve security.
2343
bd49e16e 2344 If unsure, select "Emulate execution only".
3dc33bd3 2345
3dc33bd3 2346 config LEGACY_VSYSCALL_EMULATE
bd49e16e 2347 bool "Full emulation"
3dc33bd3 2348 help
bd49e16e
AL
2349 The kernel traps and emulates calls into the fixed vsyscall
2350 address mapping. This makes the mapping non-executable, but
2351 it still contains readable known contents, which could be
2352 used in certain rare security vulnerability exploits. This
2353 configuration is recommended when using legacy userspace
2354 that still uses vsyscalls along with legacy binary
2355 instrumentation tools that require code to be readable.
2356
2357 An example of this type of legacy userspace is running
2358 Pin on an old binary that still uses vsyscalls.
2359
2360 config LEGACY_VSYSCALL_XONLY
2361 bool "Emulate execution only"
2362 help
2363 The kernel traps and emulates calls into the fixed vsyscall
2364 address mapping and does not allow reads. This
2365 configuration is recommended when userspace might use the
2366 legacy vsyscall area but support for legacy binary
2367 instrumentation of legacy code is not needed. It mitigates
2368 certain uses of the vsyscall area as an ASLR-bypassing
2369 buffer.
3dc33bd3
KC
2370
2371 config LEGACY_VSYSCALL_NONE
2372 bool "None"
2373 help
2374 There will be no vsyscall mapping at all. This will
2375 eliminate any risk of ASLR bypass due to the vsyscall
2376 fixed address mapping. Attempts to use the vsyscalls
2377 will be reported to dmesg, so that either old or
2378 malicious userspace programs can be identified.
2379
2380endchoice
2381
516cbf37
TB
2382config CMDLINE_BOOL
2383 bool "Built-in kernel command line"
a7f7f624 2384 help
516cbf37
TB
2385 Allow for specifying boot arguments to the kernel at
2386 build time. On some systems (e.g. embedded ones), it is
2387 necessary or convenient to provide some or all of the
2388 kernel boot arguments with the kernel itself (that is,
2389 to not rely on the boot loader to provide them.)
2390
2391 To compile command line arguments into the kernel,
2392 set this option to 'Y', then fill in the
69711ca1 2393 boot arguments in CONFIG_CMDLINE.
516cbf37
TB
2394
2395 Systems with fully functional boot loaders (i.e. non-embedded)
2396 should leave this option set to 'N'.
2397
2398config CMDLINE
2399 string "Built-in kernel command string"
2400 depends on CMDLINE_BOOL
2401 default ""
a7f7f624 2402 help
516cbf37
TB
2403 Enter arguments here that should be compiled into the kernel
2404 image and used at boot time. If the boot loader provides a
2405 command line at boot time, it is appended to this string to
2406 form the full kernel command line, when the system boots.
2407
2408 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2409 change this behavior.
2410
2411 In most cases, the command line (whether built-in or provided
2412 by the boot loader) should specify the device for the root
2413 file system.
2414
2415config CMDLINE_OVERRIDE
2416 bool "Built-in command line overrides boot loader arguments"
645e6466 2417 depends on CMDLINE_BOOL && CMDLINE != ""
a7f7f624 2418 help
516cbf37
TB
2419 Set this option to 'Y' to have the kernel ignore the boot loader
2420 command line, and use ONLY the built-in command line.
2421
2422 This is used to work around broken boot loaders. This should
2423 be set to 'N' under normal conditions.
2424
a5b9e5a2
AL
2425config MODIFY_LDT_SYSCALL
2426 bool "Enable the LDT (local descriptor table)" if EXPERT
2427 default y
a7f7f624 2428 help
a5b9e5a2
AL
2429 Linux can allow user programs to install a per-process x86
2430 Local Descriptor Table (LDT) using the modify_ldt(2) system
2431 call. This is required to run 16-bit or segmented code such as
2432 DOSEMU or some Wine programs. It is also used by some very old
2433 threading libraries.
2434
2435 Enabling this feature adds a small amount of overhead to
2436 context switches and increases the low-level kernel attack
2437 surface. Disabling it removes the modify_ldt(2) system call.
2438
2439 Saying 'N' here may make sense for embedded or server kernels.
2440
3aac3ebe
TG
2441config STRICT_SIGALTSTACK_SIZE
2442 bool "Enforce strict size checking for sigaltstack"
2443 depends on DYNAMIC_SIGFRAME
2444 help
2445 For historical reasons MINSIGSTKSZ is a constant which became
2446 already too small with AVX512 support. Add a mechanism to
2447 enforce strict checking of the sigaltstack size against the
2448 real size of the FPU frame. This option enables the check
2449 by default. It can also be controlled via the kernel command
2450 line option 'strict_sas_size' independent of this config
2451 switch. Enabling it might break existing applications which
2452 allocate a too small sigaltstack but 'work' because they
2453 never get a signal delivered.
2454
2455 Say 'N' unless you want to really enforce this check.
2456
b700e7f0
SJ
2457source "kernel/livepatch/Kconfig"
2458
506f1d07
SR
2459endmenu
2460
3072e413
MH
2461config ARCH_HAS_ADD_PAGES
2462 def_bool y
5c11f00b 2463 depends on ARCH_ENABLE_MEMORY_HOTPLUG
3072e413 2464
f91ef222
OS
2465config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2466 def_bool y
2467
da85f865 2468menu "Power management and ACPI options"
e279b6c1
SR
2469
2470config ARCH_HIBERNATION_HEADER
3c2362e6 2471 def_bool y
44556530 2472 depends on HIBERNATION
e279b6c1
SR
2473
2474source "kernel/power/Kconfig"
2475
2476source "drivers/acpi/Kconfig"
2477
a6b68076 2478config X86_APM_BOOT
6fc108a0 2479 def_bool y
282e5aab 2480 depends on APM
a6b68076 2481
e279b6c1
SR
2482menuconfig APM
2483 tristate "APM (Advanced Power Management) BIOS support"
efefa6f6 2484 depends on X86_32 && PM_SLEEP
a7f7f624 2485 help
e279b6c1
SR
2486 APM is a BIOS specification for saving power using several different
2487 techniques. This is mostly useful for battery powered laptops with
2488 APM compliant BIOSes. If you say Y here, the system time will be
2489 reset after a RESUME operation, the /proc/apm device will provide
2490 battery status information, and user-space programs will receive
2491 notification of APM "events" (e.g. battery status change).
2492
2493 If you select "Y" here, you can disable actual use of the APM
2494 BIOS by passing the "apm=off" option to the kernel at boot time.
2495
2496 Note that the APM support is almost completely disabled for
2497 machines with more than one CPU.
2498
2499 In order to use APM, you will need supporting software. For location
151f4e2b 2500 and more information, read <file:Documentation/power/apm-acpi.rst>
2dc98fd3 2501 and the Battery Powered Linux mini-HOWTO, available from
e279b6c1
SR
2502 <http://www.tldp.org/docs.html#howto>.
2503
2504 This driver does not spin down disk drives (see the hdparm(8)
2505 manpage ("man 8 hdparm") for that), and it doesn't turn off
2506 VESA-compliant "green" monitors.
2507
2508 This driver does not support the TI 4000M TravelMate and the ACER
2509 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2510 desktop machines also don't have compliant BIOSes, and this driver
2511 may cause those machines to panic during the boot phase.
2512
2513 Generally, if you don't have a battery in your machine, there isn't
2514 much point in using this driver and you should say N. If you get
2515 random kernel OOPSes or reboots that don't seem to be related to
2516 anything, try disabling/enabling this option (or disabling/enabling
2517 APM in your BIOS).
2518
2519 Some other things you should try when experiencing seemingly random,
2520 "weird" problems:
2521
2522 1) make sure that you have enough swap space and that it is
2523 enabled.
2524 2) pass the "no-hlt" option to the kernel
2525 3) switch on floating point emulation in the kernel and pass
2526 the "no387" option to the kernel
2527 4) pass the "floppy=nodma" option to the kernel
2528 5) pass the "mem=4M" option to the kernel (thereby disabling
2529 all but the first 4 MB of RAM)
2530 6) make sure that the CPU is not over clocked.
2531 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2532 8) disable the cache from your BIOS settings
2533 9) install a fan for the video card or exchange video RAM
2534 10) install a better fan for the CPU
2535 11) exchange RAM chips
2536 12) exchange the motherboard.
2537
2538 To compile this driver as a module, choose M here: the
2539 module will be called apm.
2540
2541if APM
2542
2543config APM_IGNORE_USER_SUSPEND
2544 bool "Ignore USER SUSPEND"
a7f7f624 2545 help
e279b6c1
SR
2546 This option will ignore USER SUSPEND requests. On machines with a
2547 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2548 series notebooks, it is necessary to say Y because of a BIOS bug.
2549
2550config APM_DO_ENABLE
2551 bool "Enable PM at boot time"
a7f7f624 2552 help
e279b6c1
SR
2553 Enable APM features at boot time. From page 36 of the APM BIOS
2554 specification: "When disabled, the APM BIOS does not automatically
2555 power manage devices, enter the Standby State, enter the Suspend
2556 State, or take power saving steps in response to CPU Idle calls."
2557 This driver will make CPU Idle calls when Linux is idle (unless this
2558 feature is turned off -- see "Do CPU IDLE calls", below). This
2559 should always save battery power, but more complicated APM features
2560 will be dependent on your BIOS implementation. You may need to turn
2561 this option off if your computer hangs at boot time when using APM
2562 support, or if it beeps continuously instead of suspending. Turn
2563 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2564 T400CDT. This is off by default since most machines do fine without
2565 this feature.
2566
2567config APM_CPU_IDLE
dd8af076 2568 depends on CPU_IDLE
e279b6c1 2569 bool "Make CPU Idle calls when idle"
a7f7f624 2570 help
e279b6c1
SR
2571 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2572 On some machines, this can activate improved power savings, such as
2573 a slowed CPU clock rate, when the machine is idle. These idle calls
2574 are made after the idle loop has run for some length of time (e.g.,
2575 333 mS). On some machines, this will cause a hang at boot time or
2576 whenever the CPU becomes idle. (On machines with more than one CPU,
2577 this option does nothing.)
2578
2579config APM_DISPLAY_BLANK
2580 bool "Enable console blanking using APM"
a7f7f624 2581 help
e279b6c1
SR
2582 Enable console blanking using the APM. Some laptops can use this to
2583 turn off the LCD backlight when the screen blanker of the Linux
2584 virtual console blanks the screen. Note that this is only used by
2585 the virtual console screen blanker, and won't turn off the backlight
2586 when using the X Window system. This also doesn't have anything to
2587 do with your VESA-compliant power-saving monitor. Further, this
2588 option doesn't work for all laptops -- it might not turn off your
2589 backlight at all, or it might print a lot of errors to the console,
2590 especially if you are using gpm.
2591
2592config APM_ALLOW_INTS
2593 bool "Allow interrupts during APM BIOS calls"
a7f7f624 2594 help
e279b6c1
SR
2595 Normally we disable external interrupts while we are making calls to
2596 the APM BIOS as a measure to lessen the effects of a badly behaving
2597 BIOS implementation. The BIOS should reenable interrupts if it
2598 needs to. Unfortunately, some BIOSes do not -- especially those in
2599 many of the newer IBM Thinkpads. If you experience hangs when you
2600 suspend, try setting this to Y. Otherwise, say N.
2601
e279b6c1
SR
2602endif # APM
2603
bb0a56ec 2604source "drivers/cpufreq/Kconfig"
e279b6c1
SR
2605
2606source "drivers/cpuidle/Kconfig"
2607
27471fdb
AH
2608source "drivers/idle/Kconfig"
2609
e279b6c1
SR
2610endmenu
2611
2612
2613menu "Bus options (PCI etc.)"
2614
e279b6c1
SR
2615choice
2616 prompt "PCI access mode"
efefa6f6 2617 depends on X86_32 && PCI
e279b6c1 2618 default PCI_GOANY
a7f7f624 2619 help
e279b6c1
SR
2620 On PCI systems, the BIOS can be used to detect the PCI devices and
2621 determine their configuration. However, some old PCI motherboards
2622 have BIOS bugs and may crash if this is done. Also, some embedded
2623 PCI-based systems don't have any BIOS at all. Linux can also try to
2624 detect the PCI hardware directly without using the BIOS.
2625
2626 With this option, you can specify how Linux should detect the
2627 PCI devices. If you choose "BIOS", the BIOS will be used,
2628 if you choose "Direct", the BIOS won't be used, and if you
2629 choose "MMConfig", then PCI Express MMCONFIG will be used.
2630 If you choose "Any", the kernel will try MMCONFIG, then the
2631 direct access method and falls back to the BIOS if that doesn't
2632 work. If unsure, go with the default, which is "Any".
2633
2634config PCI_GOBIOS
2635 bool "BIOS"
2636
2637config PCI_GOMMCONFIG
2638 bool "MMConfig"
2639
2640config PCI_GODIRECT
2641 bool "Direct"
2642
3ef0e1f8 2643config PCI_GOOLPC
76fb6570 2644 bool "OLPC XO-1"
3ef0e1f8
AS
2645 depends on OLPC
2646
2bdd1b03
AS
2647config PCI_GOANY
2648 bool "Any"
2649
e279b6c1
SR
2650endchoice
2651
2652config PCI_BIOS
3c2362e6 2653 def_bool y
efefa6f6 2654 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
e279b6c1
SR
2655
2656# x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2657config PCI_DIRECT
3c2362e6 2658 def_bool y
0aba496f 2659 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
e279b6c1
SR
2660
2661config PCI_MMCONFIG
b45c9f36
JK
2662 bool "Support mmconfig PCI config space access" if X86_64
2663 default y
4590d98f 2664 depends on PCI && (ACPI || JAILHOUSE_GUEST)
b45c9f36 2665 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
e279b6c1 2666
3ef0e1f8 2667config PCI_OLPC
2bdd1b03
AS
2668 def_bool y
2669 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
3ef0e1f8 2670
b5401a96
AN
2671config PCI_XEN
2672 def_bool y
2673 depends on PCI && XEN
b5401a96 2674
8364e1f8
JK
2675config MMCONF_FAM10H
2676 def_bool y
2677 depends on X86_64 && PCI_MMCONFIG && ACPI
e279b6c1 2678
3f6ea84a 2679config PCI_CNB20LE_QUIRK
6a108a14 2680 bool "Read CNB20LE Host Bridge Windows" if EXPERT
6ea30386 2681 depends on PCI
3f6ea84a
IS
2682 help
2683 Read the PCI windows out of the CNB20LE host bridge. This allows
2684 PCI hotplug to work on systems with the CNB20LE chipset which do
2685 not have ACPI.
2686
64a5fed6
BH
2687 There's no public spec for this chipset, and this functionality
2688 is known to be incomplete.
2689
2690 You should say N unless you know you need this.
2691
3a495511 2692config ISA_BUS
17a2a129 2693 bool "ISA bus support on modern systems" if EXPERT
3a495511 2694 help
17a2a129
WBG
2695 Expose ISA bus device drivers and options available for selection and
2696 configuration. Enable this option if your target machine has an ISA
2697 bus. ISA is an older system, displaced by PCI and newer bus
2698 architectures -- if your target machine is modern, it probably does
2699 not have an ISA bus.
3a495511
WBG
2700
2701 If unsure, say N.
2702
1c00f016 2703# x86_64 have no ISA slots, but can have ISA-style DMA.
e279b6c1 2704config ISA_DMA_API
1c00f016
DR
2705 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2706 default y
2707 help
2708 Enables ISA-style DMA support for devices requiring such controllers.
2709 If unsure, say Y.
e279b6c1 2710
51e68d05
LT
2711if X86_32
2712
e279b6c1
SR
2713config ISA
2714 bool "ISA support"
a7f7f624 2715 help
e279b6c1
SR
2716 Find out whether you have ISA slots on your motherboard. ISA is the
2717 name of a bus system, i.e. the way the CPU talks to the other stuff
2718 inside your box. Other bus systems are PCI, EISA, MicroChannel
2719 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2720 newer boards don't support it. If you have ISA, say Y, otherwise N.
2721
e279b6c1
SR
2722config SCx200
2723 tristate "NatSemi SCx200 support"
a7f7f624 2724 help
e279b6c1
SR
2725 This provides basic support for National Semiconductor's
2726 (now AMD's) Geode processors. The driver probes for the
2727 PCI-IDs of several on-chip devices, so its a good dependency
2728 for other scx200_* drivers.
2729
2730 If compiled as a module, the driver is named scx200.
2731
2732config SCx200HR_TIMER
2733 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
592913ec 2734 depends on SCx200
e279b6c1 2735 default y
a7f7f624 2736 help
e279b6c1
SR
2737 This driver provides a clocksource built upon the on-chip
2738 27MHz high-resolution timer. Its also a workaround for
2739 NSC Geode SC-1100's buggy TSC, which loses time when the
2740 processor goes idle (as is done by the scheduler). The
2741 other workaround is idle=poll boot option.
2742
3ef0e1f8
AS
2743config OLPC
2744 bool "One Laptop Per Child support"
54008979 2745 depends on !X86_PAE
3c554946 2746 select GPIOLIB
dc3119e7 2747 select OF
45bb1674 2748 select OF_PROMTREE
b4e51854 2749 select IRQ_DOMAIN
0c3d931b 2750 select OLPC_EC
a7f7f624 2751 help
3ef0e1f8
AS
2752 Add support for detecting the unique features of the OLPC
2753 XO hardware.
2754
a3128588
DD
2755config OLPC_XO1_PM
2756 bool "OLPC XO-1 Power Management"
fa112cf1 2757 depends on OLPC && MFD_CS5535=y && PM_SLEEP
a7f7f624 2758 help
97c4cb71 2759 Add support for poweroff and suspend of the OLPC XO-1 laptop.
bf1ebf00 2760
cfee9597
DD
2761config OLPC_XO1_RTC
2762 bool "OLPC XO-1 Real Time Clock"
2763 depends on OLPC_XO1_PM && RTC_DRV_CMOS
a7f7f624 2764 help
cfee9597
DD
2765 Add support for the XO-1 real time clock, which can be used as a
2766 programmable wakeup source.
2767
7feda8e9
DD
2768config OLPC_XO1_SCI
2769 bool "OLPC XO-1 SCI extras"
92e830f2 2770 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
ed8e47fe 2771 depends on INPUT=y
d8d01a63 2772 select POWER_SUPPLY
a7f7f624 2773 help
7feda8e9 2774 Add support for SCI-based features of the OLPC XO-1 laptop:
7bc74b3d 2775 - EC-driven system wakeups
7feda8e9 2776 - Power button
7bc74b3d 2777 - Ebook switch
2cf2baea 2778 - Lid switch
e1040ac6
DD
2779 - AC adapter status updates
2780 - Battery status updates
7feda8e9 2781
a0f30f59
DD
2782config OLPC_XO15_SCI
2783 bool "OLPC XO-1.5 SCI extras"
d8d01a63
DD
2784 depends on OLPC && ACPI
2785 select POWER_SUPPLY
a7f7f624 2786 help
a0f30f59
DD
2787 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2788 - EC-driven system wakeups
2789 - AC adapter status updates
2790 - Battery status updates
bf1ebf00 2791
d4f3e350
EW
2792config ALIX
2793 bool "PCEngines ALIX System Support (LED setup)"
2794 select GPIOLIB
a7f7f624 2795 help
d4f3e350
EW
2796 This option enables system support for the PCEngines ALIX.
2797 At present this just sets up LEDs for GPIO control on
2798 ALIX2/3/6 boards. However, other system specific setup should
2799 get added here.
2800
2801 Note: You must still enable the drivers for GPIO and LED support
2802 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2803
2804 Note: You have to set alix.force=1 for boards with Award BIOS.
2805
da4e3302
PP
2806config NET5501
2807 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2808 select GPIOLIB
a7f7f624 2809 help
da4e3302
PP
2810 This option enables system support for the Soekris Engineering net5501.
2811
3197059a
PP
2812config GEOS
2813 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2814 select GPIOLIB
2815 depends on DMI
a7f7f624 2816 help
3197059a
PP
2817 This option enables system support for the Traverse Technologies GEOS.
2818
7d029125
VD
2819config TS5500
2820 bool "Technologic Systems TS-5500 platform support"
2821 depends on MELAN
2822 select CHECK_SIGNATURE
2823 select NEW_LEDS
2824 select LEDS_CLASS
a7f7f624 2825 help
7d029125
VD
2826 This option enables system support for the Technologic Systems TS-5500.
2827
bc0120fd
SR
2828endif # X86_32
2829
23ac4ae8 2830config AMD_NB
e279b6c1 2831 def_bool y
0e152cd7 2832 depends on CPU_SUP_AMD && PCI
e279b6c1 2833
e279b6c1
SR
2834endmenu
2835
2836
1572497c 2837menu "Binary Emulations"
e279b6c1
SR
2838
2839config IA32_EMULATION
2840 bool "IA32 Emulation"
2841 depends on X86_64
39f88911 2842 select ARCH_WANT_OLD_COMPAT_IPC
d1603990 2843 select BINFMT_ELF
39f88911 2844 select COMPAT_OLD_SIGACTION
a7f7f624 2845 help
5fd92e65
L
2846 Include code to run legacy 32-bit programs under a
2847 64-bit kernel. You should likely turn this on, unless you're
2848 100% sure that you don't have any 32-bit programs left.
e279b6c1
SR
2849
2850config IA32_AOUT
8f9ca475
IM
2851 tristate "IA32 a.out support"
2852 depends on IA32_EMULATION
eac61655 2853 depends on BROKEN
a7f7f624 2854 help
8f9ca475 2855 Support old a.out binaries in the 32bit emulation.
e279b6c1 2856
0bf62763 2857config X86_X32
6ea30386 2858 bool "x32 ABI for 64-bit mode"
9b54050b 2859 depends on X86_64
a7f7f624 2860 help
5fd92e65
L
2861 Include code to run binaries for the x32 native 32-bit ABI
2862 for 64-bit processors. An x32 process gets access to the
2863 full 64-bit register file and wide data path while leaving
2864 pointers at 32 bits for smaller memory footprint.
2865
2866 You will need a recent binutils (2.22 or later) with
2867 elf32_x86_64 support enabled to compile a kernel with this
2868 option set.
2869
953fee1d
IM
2870config COMPAT_32
2871 def_bool y
2872 depends on IA32_EMULATION || X86_32
2873 select HAVE_UID16
2874 select OLD_SIGSUSPEND3
2875
e279b6c1 2876config COMPAT
3c2362e6 2877 def_bool y
0bf62763 2878 depends on IA32_EMULATION || X86_X32
e279b6c1 2879
3120e25e 2880if COMPAT
e279b6c1 2881config COMPAT_FOR_U64_ALIGNMENT
3120e25e 2882 def_bool y
e279b6c1
SR
2883
2884config SYSVIPC_COMPAT
3c2362e6 2885 def_bool y
3120e25e 2886 depends on SYSVIPC
3120e25e 2887endif
ee009e4a 2888
e279b6c1
SR
2889endmenu
2890
2891
e5beae16
KP
2892config HAVE_ATOMIC_IOMAP
2893 def_bool y
2894 depends on X86_32
2895
edf88417 2896source "arch/x86/kvm/Kconfig"
5e8ebd84
JD
2897
2898source "arch/x86/Kconfig.assembler"