1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 help 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select GENERIC_VDSO_32 18 select HAVE_DEBUG_STACKOVERFLOW 19 select KMAP_LOCAL 20 select MODULES_USE_ELF_REL 21 select OLD_SIGACTION 22 select ARCH_SPLIT_ARG64 23 24config X86_64 25 def_bool y 26 depends on 64BIT 27 # Options that are inherently 64-bit kernel only: 28 select ARCH_HAS_GIGANTIC_PAGE 29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 30 select ARCH_SUPPORTS_PER_VMA_LOCK 31 select HAVE_ARCH_SOFT_DIRTY 32 select MODULES_USE_ELF_RELA 33 select NEED_DMA_MAP_STATE 34 select SWIOTLB 35 select ARCH_HAS_ELFCORE_COMPAT 36 select ZONE_DMA32 37 38config FORCE_DYNAMIC_FTRACE 39 def_bool y 40 depends on X86_32 41 depends on FUNCTION_TRACER 42 select DYNAMIC_FTRACE 43 help 44 We keep the static function tracing (!DYNAMIC_FTRACE) around 45 in order to test the non static function tracing in the 46 generic code, as other architectures still use it. But we 47 only need to keep it around for x86_64. No need to keep it 48 for x86_32. For x86_32, force DYNAMIC_FTRACE. 49# 50# Arch settings 51# 52# ( Note that options that are marked 'if X86_64' could in principle be 53# ported to 32-bit as well. ) 54# 55config X86 56 def_bool y 57 # 58 # Note: keep this list sorted alphabetically 59 # 60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 62 select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 72 select ARCH_HAS_CACHE_LINE_SIZE 73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 74 select ARCH_HAS_CPU_FINALIZE_INIT 75 select ARCH_HAS_CPU_PASID if IOMMU_SVA 76 select ARCH_HAS_CURRENT_STACK_POINTER 77 select ARCH_HAS_DEBUG_VIRTUAL 78 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 79 select ARCH_HAS_DEVMEM_IS_ALLOWED 80 select ARCH_HAS_EARLY_DEBUG if KGDB 81 select ARCH_HAS_ELF_RANDOMIZE 82 select ARCH_HAS_FAST_MULTIPLIER 83 select ARCH_HAS_FORTIFY_SOURCE 84 select ARCH_HAS_GCOV_PROFILE_ALL 85 select ARCH_HAS_KCOV if X86_64 86 select ARCH_HAS_MEM_ENCRYPT 87 select ARCH_HAS_MEMBARRIER_SYNC_CORE 88 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 89 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 90 select ARCH_HAS_PMEM_API if X86_64 91 select ARCH_HAS_PTE_DEVMAP if X86_64 92 select ARCH_HAS_PTE_SPECIAL 93 select ARCH_HAS_HW_PTE_YOUNG 94 select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2 95 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 96 select ARCH_HAS_COPY_MC if X86_64 97 select ARCH_HAS_SET_MEMORY 98 select ARCH_HAS_SET_DIRECT_MAP 99 select ARCH_HAS_STRICT_KERNEL_RWX 100 select ARCH_HAS_STRICT_MODULE_RWX 101 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 102 select ARCH_HAS_SYSCALL_WRAPPER 103 select ARCH_HAS_UBSAN_SANITIZE_ALL 104 select ARCH_HAS_DEBUG_WX 105 select ARCH_HAS_ZONE_DMA_SET if EXPERT 106 select ARCH_HAVE_NMI_SAFE_CMPXCHG 107 select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 108 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 109 select ARCH_MIGHT_HAVE_PC_PARPORT 110 select ARCH_MIGHT_HAVE_PC_SERIO 111 select ARCH_STACKWALK 112 select ARCH_SUPPORTS_ACPI 113 select ARCH_SUPPORTS_ATOMIC_RMW 114 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 115 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 116 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 117 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 118 select ARCH_SUPPORTS_CFI_CLANG if X86_64 119 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 120 select ARCH_SUPPORTS_LTO_CLANG 121 select ARCH_SUPPORTS_LTO_CLANG_THIN 122 select ARCH_USE_BUILTIN_BSWAP 123 select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64 124 select ARCH_USE_MEMTEST 125 select ARCH_USE_QUEUED_RWLOCKS 126 select ARCH_USE_QUEUED_SPINLOCKS 127 select ARCH_USE_SYM_ANNOTATIONS 128 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 129 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 130 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 131 select ARCH_WANTS_NO_INSTR 132 select ARCH_WANT_GENERAL_HUGETLB 133 select ARCH_WANT_HUGE_PMD_SHARE 134 select ARCH_WANT_LD_ORPHAN_WARN 135 select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64 136 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 137 select ARCH_WANTS_THP_SWAP if X86_64 138 select ARCH_HAS_PARANOID_L1D_FLUSH 139 select BUILDTIME_TABLE_SORT 140 select CLKEVT_I8253 141 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 142 select CLOCKSOURCE_WATCHDOG 143 # Word-size accesses may read uninitialized data past the trailing \0 144 # in strings and cause false KMSAN reports. 145 select DCACHE_WORD_ACCESS if !KMSAN 146 select DYNAMIC_SIGFRAME 147 select EDAC_ATOMIC_SCRUB 148 select EDAC_SUPPORT 149 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 150 select GENERIC_CLOCKEVENTS_MIN_ADJUST 151 select GENERIC_CMOS_UPDATE 152 select GENERIC_CPU_AUTOPROBE 153 select GENERIC_CPU_DEVICES 154 select GENERIC_CPU_VULNERABILITIES 155 select GENERIC_EARLY_IOREMAP 156 select GENERIC_ENTRY 157 select GENERIC_IOMAP 158 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 159 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 160 select GENERIC_IRQ_MIGRATION if SMP 161 select GENERIC_IRQ_PROBE 162 select GENERIC_IRQ_RESERVATION_MODE 163 select GENERIC_IRQ_SHOW 164 select GENERIC_PENDING_IRQ if SMP 165 select GENERIC_PTDUMP 166 select GENERIC_SMP_IDLE_THREAD 167 select GENERIC_TIME_VSYSCALL 168 select GENERIC_GETTIMEOFDAY 169 select GENERIC_VDSO_TIME_NS 170 select GUP_GET_PXX_LOW_HIGH if X86_PAE 171 select HARDIRQS_SW_RESEND 172 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 173 select HAS_IOPORT 174 select HAVE_ACPI_APEI if ACPI 175 select HAVE_ACPI_APEI_NMI if ACPI 176 select HAVE_ALIGNED_STRUCT_PAGE 177 select HAVE_ARCH_AUDITSYSCALL 178 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 179 select HAVE_ARCH_HUGE_VMALLOC if X86_64 180 select HAVE_ARCH_JUMP_LABEL 181 select HAVE_ARCH_JUMP_LABEL_RELATIVE 182 select HAVE_ARCH_KASAN if X86_64 183 select HAVE_ARCH_KASAN_VMALLOC if X86_64 184 select HAVE_ARCH_KFENCE 185 select HAVE_ARCH_KMSAN if X86_64 186 select HAVE_ARCH_KGDB 187 select HAVE_ARCH_MMAP_RND_BITS if MMU 188 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 189 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 190 select HAVE_ARCH_PREL32_RELOCATIONS 191 select HAVE_ARCH_SECCOMP_FILTER 192 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 193 select HAVE_ARCH_STACKLEAK 194 select HAVE_ARCH_TRACEHOOK 195 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 196 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 197 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 198 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 199 select HAVE_ARCH_VMAP_STACK if X86_64 200 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 201 select HAVE_ARCH_WITHIN_STACK_FRAMES 202 select HAVE_ASM_MODVERSIONS 203 select HAVE_CMPXCHG_DOUBLE 204 select HAVE_CMPXCHG_LOCAL 205 select HAVE_CONTEXT_TRACKING_USER if X86_64 206 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 207 select HAVE_C_RECORDMCOUNT 208 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 209 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 210 select HAVE_BUILDTIME_MCOUNT_SORT 211 select HAVE_DEBUG_KMEMLEAK 212 select HAVE_DMA_CONTIGUOUS 213 select HAVE_DYNAMIC_FTRACE 214 select HAVE_DYNAMIC_FTRACE_WITH_REGS 215 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 216 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 217 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 218 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 219 select HAVE_EBPF_JIT 220 select HAVE_EFFICIENT_UNALIGNED_ACCESS 221 select HAVE_EISA 222 select HAVE_EXIT_THREAD 223 select HAVE_FAST_GUP 224 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 225 select HAVE_FTRACE_MCOUNT_RECORD 226 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 227 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 228 select HAVE_FUNCTION_TRACER 229 select HAVE_GCC_PLUGINS 230 select HAVE_HW_BREAKPOINT 231 select HAVE_IOREMAP_PROT 232 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 233 select HAVE_IRQ_TIME_ACCOUNTING 234 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 235 select HAVE_KERNEL_BZIP2 236 select HAVE_KERNEL_GZIP 237 select HAVE_KERNEL_LZ4 238 select HAVE_KERNEL_LZMA 239 select HAVE_KERNEL_LZO 240 select HAVE_KERNEL_XZ 241 select HAVE_KERNEL_ZSTD 242 select HAVE_KPROBES 243 select HAVE_KPROBES_ON_FTRACE 244 select HAVE_FUNCTION_ERROR_INJECTION 245 select HAVE_KRETPROBES 246 select HAVE_RETHOOK 247 select HAVE_KVM 248 select HAVE_LIVEPATCH if X86_64 249 select HAVE_MIXED_BREAKPOINTS_REGS 250 select HAVE_MOD_ARCH_SPECIFIC 251 select HAVE_MOVE_PMD 252 select HAVE_MOVE_PUD 253 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 254 select HAVE_NMI 255 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 256 select HAVE_OBJTOOL if X86_64 257 select HAVE_OPTPROBES 258 select HAVE_PCSPKR_PLATFORM 259 select HAVE_PERF_EVENTS 260 select HAVE_PERF_EVENTS_NMI 261 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 262 select HAVE_PCI 263 select HAVE_PERF_REGS 264 select HAVE_PERF_USER_STACK_DUMP 265 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 266 select MMU_GATHER_MERGE_VMAS 267 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 268 select HAVE_REGS_AND_STACK_ACCESS_API 269 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 270 select HAVE_FUNCTION_ARG_ACCESS_API 271 select HAVE_SETUP_PER_CPU_AREA 272 select HAVE_SOFTIRQ_ON_OWN_STACK 273 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 274 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 275 select HAVE_STATIC_CALL 276 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 277 select HAVE_PREEMPT_DYNAMIC_CALL 278 select HAVE_RSEQ 279 select HAVE_RUST if X86_64 280 select HAVE_SYSCALL_TRACEPOINTS 281 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 282 select HAVE_UNSTABLE_SCHED_CLOCK 283 select HAVE_USER_RETURN_NOTIFIER 284 select HAVE_GENERIC_VDSO 285 select HOTPLUG_PARALLEL if SMP && X86_64 286 select HOTPLUG_SMT if SMP 287 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 288 select IRQ_FORCED_THREADING 289 select LOCK_MM_AND_FIND_VMA 290 select NEED_PER_CPU_EMBED_FIRST_CHUNK 291 select NEED_PER_CPU_PAGE_FIRST_CHUNK 292 select NEED_SG_DMA_LENGTH 293 select PCI_DOMAINS if PCI 294 select PCI_LOCKLESS_CONFIG if PCI 295 select PERF_EVENTS 296 select RTC_LIB 297 select RTC_MC146818_LIB 298 select SPARSE_IRQ 299 select SYSCTL_EXCEPTION_TRACE 300 select THREAD_INFO_IN_TASK 301 select TRACE_IRQFLAGS_SUPPORT 302 select TRACE_IRQFLAGS_NMI_SUPPORT 303 select USER_STACKTRACE_SUPPORT 304 select HAVE_ARCH_KCSAN if X86_64 305 select PROC_PID_ARCH_STATUS if PROC_FS 306 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 307 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 308 select FUNCTION_ALIGNMENT_4B 309 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 310 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 311 312config INSTRUCTION_DECODER 313 def_bool y 314 depends on KPROBES || PERF_EVENTS || UPROBES 315 316config OUTPUT_FORMAT 317 string 318 default "elf32-i386" if X86_32 319 default "elf64-x86-64" if X86_64 320 321config LOCKDEP_SUPPORT 322 def_bool y 323 324config STACKTRACE_SUPPORT 325 def_bool y 326 327config MMU 328 def_bool y 329 330config ARCH_MMAP_RND_BITS_MIN 331 default 28 if 64BIT 332 default 8 333 334config ARCH_MMAP_RND_BITS_MAX 335 default 32 if 64BIT 336 default 16 337 338config ARCH_MMAP_RND_COMPAT_BITS_MIN 339 default 8 340 341config ARCH_MMAP_RND_COMPAT_BITS_MAX 342 default 16 343 344config SBUS 345 bool 346 347config GENERIC_ISA_DMA 348 def_bool y 349 depends on ISA_DMA_API 350 351config GENERIC_CSUM 352 bool 353 default y if KMSAN || KASAN 354 355config GENERIC_BUG 356 def_bool y 357 depends on BUG 358 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 359 360config GENERIC_BUG_RELATIVE_POINTERS 361 bool 362 363config ARCH_MAY_HAVE_PC_FDC 364 def_bool y 365 depends on ISA_DMA_API 366 367config GENERIC_CALIBRATE_DELAY 368 def_bool y 369 370config ARCH_HAS_CPU_RELAX 371 def_bool y 372 373config ARCH_HIBERNATION_POSSIBLE 374 def_bool y 375 376config ARCH_SUSPEND_POSSIBLE 377 def_bool y 378 379config AUDIT_ARCH 380 def_bool y if X86_64 381 382config KASAN_SHADOW_OFFSET 383 hex 384 depends on KASAN 385 default 0xdffffc0000000000 386 387config HAVE_INTEL_TXT 388 def_bool y 389 depends on INTEL_IOMMU && ACPI 390 391config X86_64_SMP 392 def_bool y 393 depends on X86_64 && SMP 394 395config ARCH_SUPPORTS_UPROBES 396 def_bool y 397 398config FIX_EARLYCON_MEM 399 def_bool y 400 401config DYNAMIC_PHYSICAL_MASK 402 bool 403 404config PGTABLE_LEVELS 405 int 406 default 5 if X86_5LEVEL 407 default 4 if X86_64 408 default 3 if X86_PAE 409 default 2 410 411config CC_HAS_SANE_STACKPROTECTOR 412 bool 413 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 414 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 415 help 416 We have to make sure stack protector is unconditionally disabled if 417 the compiler produces broken code or if it does not let us control 418 the segment on 32-bit kernels. 419 420menu "Processor type and features" 421 422config SMP 423 bool "Symmetric multi-processing support" 424 help 425 This enables support for systems with more than one CPU. If you have 426 a system with only one CPU, say N. If you have a system with more 427 than one CPU, say Y. 428 429 If you say N here, the kernel will run on uni- and multiprocessor 430 machines, but will use only one CPU of a multiprocessor machine. If 431 you say Y here, the kernel will run on many, but not all, 432 uniprocessor machines. On a uniprocessor machine, the kernel 433 will run faster if you say N here. 434 435 Note that if you say Y here and choose architecture "586" or 436 "Pentium" under "Processor family", the kernel will not work on 486 437 architectures. Similarly, multiprocessor kernels for the "PPro" 438 architecture may not work on all Pentium based boards. 439 440 People using multiprocessor machines who say Y here should also say 441 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 442 Management" code will be disabled if you say Y here. 443 444 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 445 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 446 <http://www.tldp.org/docs.html#howto>. 447 448 If you don't know what to do here, say N. 449 450config X86_X2APIC 451 bool "Support x2apic" 452 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 453 help 454 This enables x2apic support on CPUs that have this feature. 455 456 This allows 32-bit apic IDs (so it can support very large systems), 457 and accesses the local apic via MSRs not via mmio. 458 459 Some Intel systems circa 2022 and later are locked into x2APIC mode 460 and can not fall back to the legacy APIC modes if SGX or TDX are 461 enabled in the BIOS. They will boot with very reduced functionality 462 without enabling this option. 463 464 If you don't know what to do here, say N. 465 466config X86_MPPARSE 467 bool "Enable MPS table" if ACPI 468 default y 469 depends on X86_LOCAL_APIC 470 help 471 For old smp systems that do not have proper acpi support. Newer systems 472 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 473 474config GOLDFISH 475 def_bool y 476 depends on X86_GOLDFISH 477 478config X86_CPU_RESCTRL 479 bool "x86 CPU resource control support" 480 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 481 select KERNFS 482 select PROC_CPU_RESCTRL if PROC_FS 483 help 484 Enable x86 CPU resource control support. 485 486 Provide support for the allocation and monitoring of system resources 487 usage by the CPU. 488 489 Intel calls this Intel Resource Director Technology 490 (Intel(R) RDT). More information about RDT can be found in the 491 Intel x86 Architecture Software Developer Manual. 492 493 AMD calls this AMD Platform Quality of Service (AMD QoS). 494 More information about AMD QoS can be found in the AMD64 Technology 495 Platform Quality of Service Extensions manual. 496 497 Say N if unsure. 498 499config X86_FRED 500 bool "Flexible Return and Event Delivery" 501 depends on X86_64 502 help 503 When enabled, try to use Flexible Return and Event Delivery 504 instead of the legacy SYSCALL/SYSENTER/IDT architecture for 505 ring transitions and exception/interrupt handling if the 506 system supports. 507 508if X86_32 509config X86_BIGSMP 510 bool "Support for big SMP systems with more than 8 CPUs" 511 depends on SMP 512 help 513 This option is needed for the systems that have more than 8 CPUs. 514 515config X86_EXTENDED_PLATFORM 516 bool "Support for extended (non-PC) x86 platforms" 517 default y 518 help 519 If you disable this option then the kernel will only support 520 standard PC platforms. (which covers the vast majority of 521 systems out there.) 522 523 If you enable this option then you'll be able to select support 524 for the following (non-PC) 32 bit x86 platforms: 525 Goldfish (Android emulator) 526 AMD Elan 527 RDC R-321x SoC 528 SGI 320/540 (Visual Workstation) 529 STA2X11-based (e.g. Northville) 530 Moorestown MID devices 531 532 If you have one of these systems, or if you want to build a 533 generic distribution kernel, say Y here - otherwise say N. 534endif # X86_32 535 536if X86_64 537config X86_EXTENDED_PLATFORM 538 bool "Support for extended (non-PC) x86 platforms" 539 default y 540 help 541 If you disable this option then the kernel will only support 542 standard PC platforms. (which covers the vast majority of 543 systems out there.) 544 545 If you enable this option then you'll be able to select support 546 for the following (non-PC) 64 bit x86 platforms: 547 Numascale NumaChip 548 ScaleMP vSMP 549 SGI Ultraviolet 550 551 If you have one of these systems, or if you want to build a 552 generic distribution kernel, say Y here - otherwise say N. 553endif # X86_64 554# This is an alphabetically sorted list of 64 bit extended platforms 555# Please maintain the alphabetic order if and when there are additions 556config X86_NUMACHIP 557 bool "Numascale NumaChip" 558 depends on X86_64 559 depends on X86_EXTENDED_PLATFORM 560 depends on NUMA 561 depends on SMP 562 depends on X86_X2APIC 563 depends on PCI_MMCONFIG 564 help 565 Adds support for Numascale NumaChip large-SMP systems. Needed to 566 enable more than ~168 cores. 567 If you don't have one of these, you should say N here. 568 569config X86_VSMP 570 bool "ScaleMP vSMP" 571 select HYPERVISOR_GUEST 572 select PARAVIRT 573 depends on X86_64 && PCI 574 depends on X86_EXTENDED_PLATFORM 575 depends on SMP 576 help 577 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 578 supposed to run on these EM64T-based machines. Only choose this option 579 if you have one of these machines. 580 581config X86_UV 582 bool "SGI Ultraviolet" 583 depends on X86_64 584 depends on X86_EXTENDED_PLATFORM 585 depends on NUMA 586 depends on EFI 587 depends on KEXEC_CORE 588 depends on X86_X2APIC 589 depends on PCI 590 help 591 This option is needed in order to support SGI Ultraviolet systems. 592 If you don't have one of these, you should say N here. 593 594# Following is an alphabetically sorted list of 32 bit extended platforms 595# Please maintain the alphabetic order if and when there are additions 596 597config X86_GOLDFISH 598 bool "Goldfish (Virtual Platform)" 599 depends on X86_EXTENDED_PLATFORM 600 help 601 Enable support for the Goldfish virtual platform used primarily 602 for Android development. Unless you are building for the Android 603 Goldfish emulator say N here. 604 605config X86_INTEL_CE 606 bool "CE4100 TV platform" 607 depends on PCI 608 depends on PCI_GODIRECT 609 depends on X86_IO_APIC 610 depends on X86_32 611 depends on X86_EXTENDED_PLATFORM 612 select X86_REBOOTFIXUPS 613 select OF 614 select OF_EARLY_FLATTREE 615 help 616 Select for the Intel CE media processor (CE4100) SOC. 617 This option compiles in support for the CE4100 SOC for settop 618 boxes and media devices. 619 620config X86_INTEL_MID 621 bool "Intel MID platform support" 622 depends on X86_EXTENDED_PLATFORM 623 depends on X86_PLATFORM_DEVICES 624 depends on PCI 625 depends on X86_64 || (PCI_GOANY && X86_32) 626 depends on X86_IO_APIC 627 select I2C 628 select DW_APB_TIMER 629 select INTEL_SCU_PCI 630 help 631 Select to build a kernel capable of supporting Intel MID (Mobile 632 Internet Device) platform systems which do not have the PCI legacy 633 interfaces. If you are building for a PC class system say N here. 634 635 Intel MID platforms are based on an Intel processor and chipset which 636 consume less power than most of the x86 derivatives. 637 638config X86_INTEL_QUARK 639 bool "Intel Quark platform support" 640 depends on X86_32 641 depends on X86_EXTENDED_PLATFORM 642 depends on X86_PLATFORM_DEVICES 643 depends on X86_TSC 644 depends on PCI 645 depends on PCI_GOANY 646 depends on X86_IO_APIC 647 select IOSF_MBI 648 select INTEL_IMR 649 select COMMON_CLK 650 help 651 Select to include support for Quark X1000 SoC. 652 Say Y here if you have a Quark based system such as the Arduino 653 compatible Intel Galileo. 654 655config X86_INTEL_LPSS 656 bool "Intel Low Power Subsystem Support" 657 depends on X86 && ACPI && PCI 658 select COMMON_CLK 659 select PINCTRL 660 select IOSF_MBI 661 help 662 Select to build support for Intel Low Power Subsystem such as 663 found on Intel Lynxpoint PCH. Selecting this option enables 664 things like clock tree (common clock framework) and pincontrol 665 which are needed by the LPSS peripheral drivers. 666 667config X86_AMD_PLATFORM_DEVICE 668 bool "AMD ACPI2Platform devices support" 669 depends on ACPI 670 select COMMON_CLK 671 select PINCTRL 672 help 673 Select to interpret AMD specific ACPI device to platform device 674 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 675 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 676 implemented under PINCTRL subsystem. 677 678config IOSF_MBI 679 tristate "Intel SoC IOSF Sideband support for SoC platforms" 680 depends on PCI 681 help 682 This option enables sideband register access support for Intel SoC 683 platforms. On these platforms the IOSF sideband is used in lieu of 684 MSR's for some register accesses, mostly but not limited to thermal 685 and power. Drivers may query the availability of this device to 686 determine if they need the sideband in order to work on these 687 platforms. The sideband is available on the following SoC products. 688 This list is not meant to be exclusive. 689 - BayTrail 690 - Braswell 691 - Quark 692 693 You should say Y if you are running a kernel on one of these SoC's. 694 695config IOSF_MBI_DEBUG 696 bool "Enable IOSF sideband access through debugfs" 697 depends on IOSF_MBI && DEBUG_FS 698 help 699 Select this option to expose the IOSF sideband access registers (MCR, 700 MDR, MCRX) through debugfs to write and read register information from 701 different units on the SoC. This is most useful for obtaining device 702 state information for debug and analysis. As this is a general access 703 mechanism, users of this option would have specific knowledge of the 704 device they want to access. 705 706 If you don't require the option or are in doubt, say N. 707 708config X86_RDC321X 709 bool "RDC R-321x SoC" 710 depends on X86_32 711 depends on X86_EXTENDED_PLATFORM 712 select M486 713 select X86_REBOOTFIXUPS 714 help 715 This option is needed for RDC R-321x system-on-chip, also known 716 as R-8610-(G). 717 If you don't have one of these chips, you should say N here. 718 719config X86_32_NON_STANDARD 720 bool "Support non-standard 32-bit SMP architectures" 721 depends on X86_32 && SMP 722 depends on X86_EXTENDED_PLATFORM 723 help 724 This option compiles in the bigsmp and STA2X11 default 725 subarchitectures. It is intended for a generic binary 726 kernel. If you select them all, kernel will probe it one by 727 one and will fallback to default. 728 729# Alphabetically sorted list of Non standard 32 bit platforms 730 731config X86_SUPPORTS_MEMORY_FAILURE 732 def_bool y 733 # MCE code calls memory_failure(): 734 depends on X86_MCE 735 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 736 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 737 depends on X86_64 || !SPARSEMEM 738 select ARCH_SUPPORTS_MEMORY_FAILURE 739 740config STA2X11 741 bool "STA2X11 Companion Chip Support" 742 depends on X86_32_NON_STANDARD && PCI 743 select SWIOTLB 744 select MFD_STA2X11 745 select GPIOLIB 746 help 747 This adds support for boards based on the STA2X11 IO-Hub, 748 a.k.a. "ConneXt". The chip is used in place of the standard 749 PC chipset, so all "standard" peripherals are missing. If this 750 option is selected the kernel will still be able to boot on 751 standard PC machines. 752 753config X86_32_IRIS 754 tristate "Eurobraille/Iris poweroff module" 755 depends on X86_32 756 help 757 The Iris machines from EuroBraille do not have APM or ACPI support 758 to shut themselves down properly. A special I/O sequence is 759 needed to do so, which is what this module does at 760 kernel shutdown. 761 762 This is only for Iris machines from EuroBraille. 763 764 If unused, say N. 765 766config SCHED_OMIT_FRAME_POINTER 767 def_bool y 768 prompt "Single-depth WCHAN output" 769 depends on X86 770 help 771 Calculate simpler /proc/<PID>/wchan values. If this option 772 is disabled then wchan values will recurse back to the 773 caller function. This provides more accurate wchan values, 774 at the expense of slightly more scheduling overhead. 775 776 If in doubt, say "Y". 777 778menuconfig HYPERVISOR_GUEST 779 bool "Linux guest support" 780 help 781 Say Y here to enable options for running Linux under various hyper- 782 visors. This option enables basic hypervisor detection and platform 783 setup. 784 785 If you say N, all options in this submenu will be skipped and 786 disabled, and Linux guest support won't be built in. 787 788if HYPERVISOR_GUEST 789 790config PARAVIRT 791 bool "Enable paravirtualization code" 792 depends on HAVE_STATIC_CALL 793 help 794 This changes the kernel so it can modify itself when it is run 795 under a hypervisor, potentially improving performance significantly 796 over full virtualization. However, when run without a hypervisor 797 the kernel is theoretically slower and slightly larger. 798 799config PARAVIRT_XXL 800 bool 801 802config PARAVIRT_DEBUG 803 bool "paravirt-ops debugging" 804 depends on PARAVIRT && DEBUG_KERNEL 805 help 806 Enable to debug paravirt_ops internals. Specifically, BUG if 807 a paravirt_op is missing when it is called. 808 809config PARAVIRT_SPINLOCKS 810 bool "Paravirtualization layer for spinlocks" 811 depends on PARAVIRT && SMP 812 help 813 Paravirtualized spinlocks allow a pvops backend to replace the 814 spinlock implementation with something virtualization-friendly 815 (for example, block the virtual CPU rather than spinning). 816 817 It has a minimal impact on native kernels and gives a nice performance 818 benefit on paravirtualized KVM / Xen kernels. 819 820 If you are unsure how to answer this question, answer Y. 821 822config X86_HV_CALLBACK_VECTOR 823 def_bool n 824 825source "arch/x86/xen/Kconfig" 826 827config KVM_GUEST 828 bool "KVM Guest support (including kvmclock)" 829 depends on PARAVIRT 830 select PARAVIRT_CLOCK 831 select ARCH_CPUIDLE_HALTPOLL 832 select X86_HV_CALLBACK_VECTOR 833 default y 834 help 835 This option enables various optimizations for running under the KVM 836 hypervisor. It includes a paravirtualized clock, so that instead 837 of relying on a PIT (or probably other) emulation by the 838 underlying device model, the host provides the guest with 839 timing infrastructure such as time of day, and system time 840 841config ARCH_CPUIDLE_HALTPOLL 842 def_bool n 843 prompt "Disable host haltpoll when loading haltpoll driver" 844 help 845 If virtualized under KVM, disable host haltpoll. 846 847config PVH 848 bool "Support for running PVH guests" 849 help 850 This option enables the PVH entry point for guest virtual machines 851 as specified in the x86/HVM direct boot ABI. 852 853config PARAVIRT_TIME_ACCOUNTING 854 bool "Paravirtual steal time accounting" 855 depends on PARAVIRT 856 help 857 Select this option to enable fine granularity task steal time 858 accounting. Time spent executing other tasks in parallel with 859 the current vCPU is discounted from the vCPU power. To account for 860 that, there can be a small performance impact. 861 862 If in doubt, say N here. 863 864config PARAVIRT_CLOCK 865 bool 866 867config JAILHOUSE_GUEST 868 bool "Jailhouse non-root cell support" 869 depends on X86_64 && PCI 870 select X86_PM_TIMER 871 help 872 This option allows to run Linux as guest in a Jailhouse non-root 873 cell. You can leave this option disabled if you only want to start 874 Jailhouse and run Linux afterwards in the root cell. 875 876config ACRN_GUEST 877 bool "ACRN Guest support" 878 depends on X86_64 879 select X86_HV_CALLBACK_VECTOR 880 help 881 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 882 a flexible, lightweight reference open-source hypervisor, built with 883 real-time and safety-criticality in mind. It is built for embedded 884 IOT with small footprint and real-time features. More details can be 885 found in https://projectacrn.org/. 886 887config INTEL_TDX_GUEST 888 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 889 depends on X86_64 && CPU_SUP_INTEL 890 depends on X86_X2APIC 891 depends on EFI_STUB 892 select ARCH_HAS_CC_PLATFORM 893 select X86_MEM_ENCRYPT 894 select X86_MCE 895 select UNACCEPTED_MEMORY 896 help 897 Support running as a guest under Intel TDX. Without this support, 898 the guest kernel can not boot or run under TDX. 899 TDX includes memory encryption and integrity capabilities 900 which protect the confidentiality and integrity of guest 901 memory contents and CPU state. TDX guests are protected from 902 some attacks from the VMM. 903 904endif # HYPERVISOR_GUEST 905 906source "arch/x86/Kconfig.cpu" 907 908config HPET_TIMER 909 def_bool X86_64 910 prompt "HPET Timer Support" if X86_32 911 help 912 Use the IA-PC HPET (High Precision Event Timer) to manage 913 time in preference to the PIT and RTC, if a HPET is 914 present. 915 HPET is the next generation timer replacing legacy 8254s. 916 The HPET provides a stable time base on SMP 917 systems, unlike the TSC, but it is more expensive to access, 918 as it is off-chip. The interface used is documented 919 in the HPET spec, revision 1. 920 921 You can safely choose Y here. However, HPET will only be 922 activated if the platform and the BIOS support this feature. 923 Otherwise the 8254 will be used for timing services. 924 925 Choose N to continue using the legacy 8254 timer. 926 927config HPET_EMULATE_RTC 928 def_bool y 929 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 930 931# Mark as expert because too many people got it wrong. 932# The code disables itself when not needed. 933config DMI 934 default y 935 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 936 bool "Enable DMI scanning" if EXPERT 937 help 938 Enabled scanning of DMI to identify machine quirks. Say Y 939 here unless you have verified that your setup is not 940 affected by entries in the DMI blacklist. Required by PNP 941 BIOS code. 942 943config GART_IOMMU 944 bool "Old AMD GART IOMMU support" 945 select DMA_OPS 946 select IOMMU_HELPER 947 select SWIOTLB 948 depends on X86_64 && PCI && AMD_NB 949 help 950 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 951 GART based hardware IOMMUs. 952 953 The GART supports full DMA access for devices with 32-bit access 954 limitations, on systems with more than 3 GB. This is usually needed 955 for USB, sound, many IDE/SATA chipsets and some other devices. 956 957 Newer systems typically have a modern AMD IOMMU, supported via 958 the CONFIG_AMD_IOMMU=y config option. 959 960 In normal configurations this driver is only active when needed: 961 there's more than 3 GB of memory and the system contains a 962 32-bit limited device. 963 964 If unsure, say Y. 965 966config BOOT_VESA_SUPPORT 967 bool 968 help 969 If true, at least one selected framebuffer driver can take advantage 970 of VESA video modes set at an early boot stage via the vga= parameter. 971 972config MAXSMP 973 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 974 depends on X86_64 && SMP && DEBUG_KERNEL 975 select CPUMASK_OFFSTACK 976 help 977 Enable maximum number of CPUS and NUMA Nodes for this architecture. 978 If unsure, say N. 979 980# 981# The maximum number of CPUs supported: 982# 983# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 984# and which can be configured interactively in the 985# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 986# 987# The ranges are different on 32-bit and 64-bit kernels, depending on 988# hardware capabilities and scalability features of the kernel. 989# 990# ( If MAXSMP is enabled we just use the highest possible value and disable 991# interactive configuration. ) 992# 993 994config NR_CPUS_RANGE_BEGIN 995 int 996 default NR_CPUS_RANGE_END if MAXSMP 997 default 1 if !SMP 998 default 2 999 1000config NR_CPUS_RANGE_END 1001 int 1002 depends on X86_32 1003 default 64 if SMP && X86_BIGSMP 1004 default 8 if SMP && !X86_BIGSMP 1005 default 1 if !SMP 1006 1007config NR_CPUS_RANGE_END 1008 int 1009 depends on X86_64 1010 default 8192 if SMP && CPUMASK_OFFSTACK 1011 default 512 if SMP && !CPUMASK_OFFSTACK 1012 default 1 if !SMP 1013 1014config NR_CPUS_DEFAULT 1015 int 1016 depends on X86_32 1017 default 32 if X86_BIGSMP 1018 default 8 if SMP 1019 default 1 if !SMP 1020 1021config NR_CPUS_DEFAULT 1022 int 1023 depends on X86_64 1024 default 8192 if MAXSMP 1025 default 64 if SMP 1026 default 1 if !SMP 1027 1028config NR_CPUS 1029 int "Maximum number of CPUs" if SMP && !MAXSMP 1030 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1031 default NR_CPUS_DEFAULT 1032 help 1033 This allows you to specify the maximum number of CPUs which this 1034 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1035 supported value is 8192, otherwise the maximum value is 512. The 1036 minimum value which makes sense is 2. 1037 1038 This is purely to save memory: each supported CPU adds about 8KB 1039 to the kernel image. 1040 1041config SCHED_CLUSTER 1042 bool "Cluster scheduler support" 1043 depends on SMP 1044 default y 1045 help 1046 Cluster scheduler support improves the CPU scheduler's decision 1047 making when dealing with machines that have clusters of CPUs. 1048 Cluster usually means a couple of CPUs which are placed closely 1049 by sharing mid-level caches, last-level cache tags or internal 1050 busses. 1051 1052config SCHED_SMT 1053 def_bool y if SMP 1054 1055config SCHED_MC 1056 def_bool y 1057 prompt "Multi-core scheduler support" 1058 depends on SMP 1059 help 1060 Multi-core scheduler support improves the CPU scheduler's decision 1061 making when dealing with multi-core CPU chips at a cost of slightly 1062 increased overhead in some places. If unsure say N here. 1063 1064config SCHED_MC_PRIO 1065 bool "CPU core priorities scheduler support" 1066 depends on SCHED_MC && CPU_SUP_INTEL 1067 select X86_INTEL_PSTATE 1068 select CPU_FREQ 1069 default y 1070 help 1071 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1072 core ordering determined at manufacturing time, which allows 1073 certain cores to reach higher turbo frequencies (when running 1074 single threaded workloads) than others. 1075 1076 Enabling this kernel feature teaches the scheduler about 1077 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1078 scheduler's CPU selection logic accordingly, so that higher 1079 overall system performance can be achieved. 1080 1081 This feature will have no effect on CPUs without this feature. 1082 1083 If unsure say Y here. 1084 1085config UP_LATE_INIT 1086 def_bool y 1087 depends on !SMP && X86_LOCAL_APIC 1088 1089config X86_UP_APIC 1090 bool "Local APIC support on uniprocessors" if !PCI_MSI 1091 default PCI_MSI 1092 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1093 help 1094 A local APIC (Advanced Programmable Interrupt Controller) is an 1095 integrated interrupt controller in the CPU. If you have a single-CPU 1096 system which has a processor with a local APIC, you can say Y here to 1097 enable and use it. If you say Y here even though your machine doesn't 1098 have a local APIC, then the kernel will still run with no slowdown at 1099 all. The local APIC supports CPU-generated self-interrupts (timer, 1100 performance counters), and the NMI watchdog which detects hard 1101 lockups. 1102 1103config X86_UP_IOAPIC 1104 bool "IO-APIC support on uniprocessors" 1105 depends on X86_UP_APIC 1106 help 1107 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1108 SMP-capable replacement for PC-style interrupt controllers. Most 1109 SMP systems and many recent uniprocessor systems have one. 1110 1111 If you have a single-CPU system with an IO-APIC, you can say Y here 1112 to use it. If you say Y here even though your machine doesn't have 1113 an IO-APIC, then the kernel will still run with no slowdown at all. 1114 1115config X86_LOCAL_APIC 1116 def_bool y 1117 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1118 select IRQ_DOMAIN_HIERARCHY 1119 1120config X86_IO_APIC 1121 def_bool y 1122 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1123 1124config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1125 bool "Reroute for broken boot IRQs" 1126 depends on X86_IO_APIC 1127 help 1128 This option enables a workaround that fixes a source of 1129 spurious interrupts. This is recommended when threaded 1130 interrupt handling is used on systems where the generation of 1131 superfluous "boot interrupts" cannot be disabled. 1132 1133 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1134 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1135 kernel does during interrupt handling). On chipsets where this 1136 boot IRQ generation cannot be disabled, this workaround keeps 1137 the original IRQ line masked so that only the equivalent "boot 1138 IRQ" is delivered to the CPUs. The workaround also tells the 1139 kernel to set up the IRQ handler on the boot IRQ line. In this 1140 way only one interrupt is delivered to the kernel. Otherwise 1141 the spurious second interrupt may cause the kernel to bring 1142 down (vital) interrupt lines. 1143 1144 Only affects "broken" chipsets. Interrupt sharing may be 1145 increased on these systems. 1146 1147config X86_MCE 1148 bool "Machine Check / overheating reporting" 1149 select GENERIC_ALLOCATOR 1150 default y 1151 help 1152 Machine Check support allows the processor to notify the 1153 kernel if it detects a problem (e.g. overheating, data corruption). 1154 The action the kernel takes depends on the severity of the problem, 1155 ranging from warning messages to halting the machine. 1156 1157config X86_MCELOG_LEGACY 1158 bool "Support for deprecated /dev/mcelog character device" 1159 depends on X86_MCE 1160 help 1161 Enable support for /dev/mcelog which is needed by the old mcelog 1162 userspace logging daemon. Consider switching to the new generation 1163 rasdaemon solution. 1164 1165config X86_MCE_INTEL 1166 def_bool y 1167 prompt "Intel MCE features" 1168 depends on X86_MCE && X86_LOCAL_APIC 1169 help 1170 Additional support for intel specific MCE features such as 1171 the thermal monitor. 1172 1173config X86_MCE_AMD 1174 def_bool y 1175 prompt "AMD MCE features" 1176 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1177 help 1178 Additional support for AMD specific MCE features such as 1179 the DRAM Error Threshold. 1180 1181config X86_ANCIENT_MCE 1182 bool "Support for old Pentium 5 / WinChip machine checks" 1183 depends on X86_32 && X86_MCE 1184 help 1185 Include support for machine check handling on old Pentium 5 or WinChip 1186 systems. These typically need to be enabled explicitly on the command 1187 line. 1188 1189config X86_MCE_THRESHOLD 1190 depends on X86_MCE_AMD || X86_MCE_INTEL 1191 def_bool y 1192 1193config X86_MCE_INJECT 1194 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1195 tristate "Machine check injector support" 1196 help 1197 Provide support for injecting machine checks for testing purposes. 1198 If you don't know what a machine check is and you don't do kernel 1199 QA it is safe to say n. 1200 1201source "arch/x86/events/Kconfig" 1202 1203config X86_LEGACY_VM86 1204 bool "Legacy VM86 support" 1205 depends on X86_32 1206 help 1207 This option allows user programs to put the CPU into V8086 1208 mode, which is an 80286-era approximation of 16-bit real mode. 1209 1210 Some very old versions of X and/or vbetool require this option 1211 for user mode setting. Similarly, DOSEMU will use it if 1212 available to accelerate real mode DOS programs. However, any 1213 recent version of DOSEMU, X, or vbetool should be fully 1214 functional even without kernel VM86 support, as they will all 1215 fall back to software emulation. Nevertheless, if you are using 1216 a 16-bit DOS program where 16-bit performance matters, vm86 1217 mode might be faster than emulation and you might want to 1218 enable this option. 1219 1220 Note that any app that works on a 64-bit kernel is unlikely to 1221 need this option, as 64-bit kernels don't, and can't, support 1222 V8086 mode. This option is also unrelated to 16-bit protected 1223 mode and is not needed to run most 16-bit programs under Wine. 1224 1225 Enabling this option increases the complexity of the kernel 1226 and slows down exception handling a tiny bit. 1227 1228 If unsure, say N here. 1229 1230config VM86 1231 bool 1232 default X86_LEGACY_VM86 1233 1234config X86_16BIT 1235 bool "Enable support for 16-bit segments" if EXPERT 1236 default y 1237 depends on MODIFY_LDT_SYSCALL 1238 help 1239 This option is required by programs like Wine to run 16-bit 1240 protected mode legacy code on x86 processors. Disabling 1241 this option saves about 300 bytes on i386, or around 6K text 1242 plus 16K runtime memory on x86-64, 1243 1244config X86_ESPFIX32 1245 def_bool y 1246 depends on X86_16BIT && X86_32 1247 1248config X86_ESPFIX64 1249 def_bool y 1250 depends on X86_16BIT && X86_64 1251 1252config X86_VSYSCALL_EMULATION 1253 bool "Enable vsyscall emulation" if EXPERT 1254 default y 1255 depends on X86_64 1256 help 1257 This enables emulation of the legacy vsyscall page. Disabling 1258 it is roughly equivalent to booting with vsyscall=none, except 1259 that it will also disable the helpful warning if a program 1260 tries to use a vsyscall. With this option set to N, offending 1261 programs will just segfault, citing addresses of the form 1262 0xffffffffff600?00. 1263 1264 This option is required by many programs built before 2013, and 1265 care should be used even with newer programs if set to N. 1266 1267 Disabling this option saves about 7K of kernel size and 1268 possibly 4K of additional runtime pagetable memory. 1269 1270config X86_IOPL_IOPERM 1271 bool "IOPERM and IOPL Emulation" 1272 default y 1273 help 1274 This enables the ioperm() and iopl() syscalls which are necessary 1275 for legacy applications. 1276 1277 Legacy IOPL support is an overbroad mechanism which allows user 1278 space aside of accessing all 65536 I/O ports also to disable 1279 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1280 capabilities and permission from potentially active security 1281 modules. 1282 1283 The emulation restricts the functionality of the syscall to 1284 only allowing the full range I/O port access, but prevents the 1285 ability to disable interrupts from user space which would be 1286 granted if the hardware IOPL mechanism would be used. 1287 1288config TOSHIBA 1289 tristate "Toshiba Laptop support" 1290 depends on X86_32 1291 help 1292 This adds a driver to safely access the System Management Mode of 1293 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1294 not work on models with a Phoenix BIOS. The System Management Mode 1295 is used to set the BIOS and power saving options on Toshiba portables. 1296 1297 For information on utilities to make use of this driver see the 1298 Toshiba Linux utilities web site at: 1299 <http://www.buzzard.org.uk/toshiba/>. 1300 1301 Say Y if you intend to run this kernel on a Toshiba portable. 1302 Say N otherwise. 1303 1304config X86_REBOOTFIXUPS 1305 bool "Enable X86 board specific fixups for reboot" 1306 depends on X86_32 1307 help 1308 This enables chipset and/or board specific fixups to be done 1309 in order to get reboot to work correctly. This is only needed on 1310 some combinations of hardware and BIOS. The symptom, for which 1311 this config is intended, is when reboot ends with a stalled/hung 1312 system. 1313 1314 Currently, the only fixup is for the Geode machines using 1315 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1316 1317 Say Y if you want to enable the fixup. Currently, it's safe to 1318 enable this option even if you don't need it. 1319 Say N otherwise. 1320 1321config MICROCODE 1322 def_bool y 1323 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1324 1325config MICROCODE_INITRD32 1326 def_bool y 1327 depends on MICROCODE && X86_32 && BLK_DEV_INITRD 1328 1329config MICROCODE_LATE_LOADING 1330 bool "Late microcode loading (DANGEROUS)" 1331 default n 1332 depends on MICROCODE && SMP 1333 help 1334 Loading microcode late, when the system is up and executing instructions 1335 is a tricky business and should be avoided if possible. Just the sequence 1336 of synchronizing all cores and SMT threads is one fragile dance which does 1337 not guarantee that cores might not softlock after the loading. Therefore, 1338 use this at your own risk. Late loading taints the kernel unless the 1339 microcode header indicates that it is safe for late loading via the 1340 minimal revision check. This minimal revision check can be enforced on 1341 the kernel command line with "microcode.minrev=Y". 1342 1343config MICROCODE_LATE_FORCE_MINREV 1344 bool "Enforce late microcode loading minimal revision check" 1345 default n 1346 depends on MICROCODE_LATE_LOADING 1347 help 1348 To prevent that users load microcode late which modifies already 1349 in use features, newer microcode patches have a minimum revision field 1350 in the microcode header, which tells the kernel which minimum 1351 revision must be active in the CPU to safely load that new microcode 1352 late into the running system. If disabled the check will not 1353 be enforced but the kernel will be tainted when the minimal 1354 revision check fails. 1355 1356 This minimal revision check can also be controlled via the 1357 "microcode.minrev" parameter on the kernel command line. 1358 1359 If unsure say Y. 1360 1361config X86_MSR 1362 tristate "/dev/cpu/*/msr - Model-specific register support" 1363 help 1364 This device gives privileged processes access to the x86 1365 Model-Specific Registers (MSRs). It is a character device with 1366 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1367 MSR accesses are directed to a specific CPU on multi-processor 1368 systems. 1369 1370config X86_CPUID 1371 tristate "/dev/cpu/*/cpuid - CPU information support" 1372 help 1373 This device gives processes access to the x86 CPUID instruction to 1374 be executed on a specific processor. It is a character device 1375 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1376 /dev/cpu/31/cpuid. 1377 1378choice 1379 prompt "High Memory Support" 1380 default HIGHMEM4G 1381 depends on X86_32 1382 1383config NOHIGHMEM 1384 bool "off" 1385 help 1386 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1387 However, the address space of 32-bit x86 processors is only 4 1388 Gigabytes large. That means that, if you have a large amount of 1389 physical memory, not all of it can be "permanently mapped" by the 1390 kernel. The physical memory that's not permanently mapped is called 1391 "high memory". 1392 1393 If you are compiling a kernel which will never run on a machine with 1394 more than 1 Gigabyte total physical RAM, answer "off" here (default 1395 choice and suitable for most users). This will result in a "3GB/1GB" 1396 split: 3GB are mapped so that each process sees a 3GB virtual memory 1397 space and the remaining part of the 4GB virtual memory space is used 1398 by the kernel to permanently map as much physical memory as 1399 possible. 1400 1401 If the machine has between 1 and 4 Gigabytes physical RAM, then 1402 answer "4GB" here. 1403 1404 If more than 4 Gigabytes is used then answer "64GB" here. This 1405 selection turns Intel PAE (Physical Address Extension) mode on. 1406 PAE implements 3-level paging on IA32 processors. PAE is fully 1407 supported by Linux, PAE mode is implemented on all recent Intel 1408 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1409 then the kernel will not boot on CPUs that don't support PAE! 1410 1411 The actual amount of total physical memory will either be 1412 auto detected or can be forced by using a kernel command line option 1413 such as "mem=256M". (Try "man bootparam" or see the documentation of 1414 your boot loader (lilo or loadlin) about how to pass options to the 1415 kernel at boot time.) 1416 1417 If unsure, say "off". 1418 1419config HIGHMEM4G 1420 bool "4GB" 1421 help 1422 Select this if you have a 32-bit processor and between 1 and 4 1423 gigabytes of physical RAM. 1424 1425config HIGHMEM64G 1426 bool "64GB" 1427 depends on X86_HAVE_PAE 1428 select X86_PAE 1429 help 1430 Select this if you have a 32-bit processor and more than 4 1431 gigabytes of physical RAM. 1432 1433endchoice 1434 1435choice 1436 prompt "Memory split" if EXPERT 1437 default VMSPLIT_3G 1438 depends on X86_32 1439 help 1440 Select the desired split between kernel and user memory. 1441 1442 If the address range available to the kernel is less than the 1443 physical memory installed, the remaining memory will be available 1444 as "high memory". Accessing high memory is a little more costly 1445 than low memory, as it needs to be mapped into the kernel first. 1446 Note that increasing the kernel address space limits the range 1447 available to user programs, making the address space there 1448 tighter. Selecting anything other than the default 3G/1G split 1449 will also likely make your kernel incompatible with binary-only 1450 kernel modules. 1451 1452 If you are not absolutely sure what you are doing, leave this 1453 option alone! 1454 1455 config VMSPLIT_3G 1456 bool "3G/1G user/kernel split" 1457 config VMSPLIT_3G_OPT 1458 depends on !X86_PAE 1459 bool "3G/1G user/kernel split (for full 1G low memory)" 1460 config VMSPLIT_2G 1461 bool "2G/2G user/kernel split" 1462 config VMSPLIT_2G_OPT 1463 depends on !X86_PAE 1464 bool "2G/2G user/kernel split (for full 2G low memory)" 1465 config VMSPLIT_1G 1466 bool "1G/3G user/kernel split" 1467endchoice 1468 1469config PAGE_OFFSET 1470 hex 1471 default 0xB0000000 if VMSPLIT_3G_OPT 1472 default 0x80000000 if VMSPLIT_2G 1473 default 0x78000000 if VMSPLIT_2G_OPT 1474 default 0x40000000 if VMSPLIT_1G 1475 default 0xC0000000 1476 depends on X86_32 1477 1478config HIGHMEM 1479 def_bool y 1480 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1481 1482config X86_PAE 1483 bool "PAE (Physical Address Extension) Support" 1484 depends on X86_32 && X86_HAVE_PAE 1485 select PHYS_ADDR_T_64BIT 1486 select SWIOTLB 1487 help 1488 PAE is required for NX support, and furthermore enables 1489 larger swapspace support for non-overcommit purposes. It 1490 has the cost of more pagetable lookup overhead, and also 1491 consumes more pagetable space per process. 1492 1493config X86_5LEVEL 1494 bool "Enable 5-level page tables support" 1495 default y 1496 select DYNAMIC_MEMORY_LAYOUT 1497 select SPARSEMEM_VMEMMAP 1498 depends on X86_64 1499 help 1500 5-level paging enables access to larger address space: 1501 up to 128 PiB of virtual address space and 4 PiB of 1502 physical address space. 1503 1504 It will be supported by future Intel CPUs. 1505 1506 A kernel with the option enabled can be booted on machines that 1507 support 4- or 5-level paging. 1508 1509 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1510 information. 1511 1512 Say N if unsure. 1513 1514config X86_DIRECT_GBPAGES 1515 def_bool y 1516 depends on X86_64 1517 help 1518 Certain kernel features effectively disable kernel 1519 linear 1 GB mappings (even if the CPU otherwise 1520 supports them), so don't confuse the user by printing 1521 that we have them enabled. 1522 1523config X86_CPA_STATISTICS 1524 bool "Enable statistic for Change Page Attribute" 1525 depends on DEBUG_FS 1526 help 1527 Expose statistics about the Change Page Attribute mechanism, which 1528 helps to determine the effectiveness of preserving large and huge 1529 page mappings when mapping protections are changed. 1530 1531config X86_MEM_ENCRYPT 1532 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1533 select DYNAMIC_PHYSICAL_MASK 1534 def_bool n 1535 1536config AMD_MEM_ENCRYPT 1537 bool "AMD Secure Memory Encryption (SME) support" 1538 depends on X86_64 && CPU_SUP_AMD 1539 depends on EFI_STUB 1540 select DMA_COHERENT_POOL 1541 select ARCH_USE_MEMREMAP_PROT 1542 select INSTRUCTION_DECODER 1543 select ARCH_HAS_CC_PLATFORM 1544 select X86_MEM_ENCRYPT 1545 select UNACCEPTED_MEMORY 1546 help 1547 Say yes to enable support for the encryption of system memory. 1548 This requires an AMD processor that supports Secure Memory 1549 Encryption (SME). 1550 1551config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1552 bool "Activate AMD Secure Memory Encryption (SME) by default" 1553 depends on AMD_MEM_ENCRYPT 1554 help 1555 Say yes to have system memory encrypted by default if running on 1556 an AMD processor that supports Secure Memory Encryption (SME). 1557 1558 If set to Y, then the encryption of system memory can be 1559 deactivated with the mem_encrypt=off command line option. 1560 1561 If set to N, then the encryption of system memory can be 1562 activated with the mem_encrypt=on command line option. 1563 1564# Common NUMA Features 1565config NUMA 1566 bool "NUMA Memory Allocation and Scheduler Support" 1567 depends on SMP 1568 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1569 default y if X86_BIGSMP 1570 select USE_PERCPU_NUMA_NODE_ID 1571 select OF_NUMA if OF 1572 help 1573 Enable NUMA (Non-Uniform Memory Access) support. 1574 1575 The kernel will try to allocate memory used by a CPU on the 1576 local memory controller of the CPU and add some more 1577 NUMA awareness to the kernel. 1578 1579 For 64-bit this is recommended if the system is Intel Core i7 1580 (or later), AMD Opteron, or EM64T NUMA. 1581 1582 For 32-bit this is only needed if you boot a 32-bit 1583 kernel on a 64-bit NUMA platform. 1584 1585 Otherwise, you should say N. 1586 1587config AMD_NUMA 1588 def_bool y 1589 prompt "Old style AMD Opteron NUMA detection" 1590 depends on X86_64 && NUMA && PCI 1591 help 1592 Enable AMD NUMA node topology detection. You should say Y here if 1593 you have a multi processor AMD system. This uses an old method to 1594 read the NUMA configuration directly from the builtin Northbridge 1595 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1596 which also takes priority if both are compiled in. 1597 1598config X86_64_ACPI_NUMA 1599 def_bool y 1600 prompt "ACPI NUMA detection" 1601 depends on X86_64 && NUMA && ACPI && PCI 1602 select ACPI_NUMA 1603 help 1604 Enable ACPI SRAT based node topology detection. 1605 1606config NUMA_EMU 1607 bool "NUMA emulation" 1608 depends on NUMA 1609 help 1610 Enable NUMA emulation. A flat machine will be split 1611 into virtual nodes when booted with "numa=fake=N", where N is the 1612 number of nodes. This is only useful for debugging. 1613 1614config NODES_SHIFT 1615 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1616 range 1 10 1617 default "10" if MAXSMP 1618 default "6" if X86_64 1619 default "3" 1620 depends on NUMA 1621 help 1622 Specify the maximum number of NUMA Nodes available on the target 1623 system. Increases memory reserved to accommodate various tables. 1624 1625config ARCH_FLATMEM_ENABLE 1626 def_bool y 1627 depends on X86_32 && !NUMA 1628 1629config ARCH_SPARSEMEM_ENABLE 1630 def_bool y 1631 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1632 select SPARSEMEM_STATIC if X86_32 1633 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1634 1635config ARCH_SPARSEMEM_DEFAULT 1636 def_bool X86_64 || (NUMA && X86_32) 1637 1638config ARCH_SELECT_MEMORY_MODEL 1639 def_bool y 1640 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1641 1642config ARCH_MEMORY_PROBE 1643 bool "Enable sysfs memory/probe interface" 1644 depends on MEMORY_HOTPLUG 1645 help 1646 This option enables a sysfs memory/probe interface for testing. 1647 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1648 If you are unsure how to answer this question, answer N. 1649 1650config ARCH_PROC_KCORE_TEXT 1651 def_bool y 1652 depends on X86_64 && PROC_KCORE 1653 1654config ILLEGAL_POINTER_VALUE 1655 hex 1656 default 0 if X86_32 1657 default 0xdead000000000000 if X86_64 1658 1659config X86_PMEM_LEGACY_DEVICE 1660 bool 1661 1662config X86_PMEM_LEGACY 1663 tristate "Support non-standard NVDIMMs and ADR protected memory" 1664 depends on PHYS_ADDR_T_64BIT 1665 depends on BLK_DEV 1666 select X86_PMEM_LEGACY_DEVICE 1667 select NUMA_KEEP_MEMINFO if NUMA 1668 select LIBNVDIMM 1669 help 1670 Treat memory marked using the non-standard e820 type of 12 as used 1671 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1672 The kernel will offer these regions to the 'pmem' driver so 1673 they can be used for persistent storage. 1674 1675 Say Y if unsure. 1676 1677config HIGHPTE 1678 bool "Allocate 3rd-level pagetables from highmem" 1679 depends on HIGHMEM 1680 help 1681 The VM uses one page table entry for each page of physical memory. 1682 For systems with a lot of RAM, this can be wasteful of precious 1683 low memory. Setting this option will put user-space page table 1684 entries in high memory. 1685 1686config X86_CHECK_BIOS_CORRUPTION 1687 bool "Check for low memory corruption" 1688 help 1689 Periodically check for memory corruption in low memory, which 1690 is suspected to be caused by BIOS. Even when enabled in the 1691 configuration, it is disabled at runtime. Enable it by 1692 setting "memory_corruption_check=1" on the kernel command 1693 line. By default it scans the low 64k of memory every 60 1694 seconds; see the memory_corruption_check_size and 1695 memory_corruption_check_period parameters in 1696 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1697 1698 When enabled with the default parameters, this option has 1699 almost no overhead, as it reserves a relatively small amount 1700 of memory and scans it infrequently. It both detects corruption 1701 and prevents it from affecting the running system. 1702 1703 It is, however, intended as a diagnostic tool; if repeatable 1704 BIOS-originated corruption always affects the same memory, 1705 you can use memmap= to prevent the kernel from using that 1706 memory. 1707 1708config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1709 bool "Set the default setting of memory_corruption_check" 1710 depends on X86_CHECK_BIOS_CORRUPTION 1711 default y 1712 help 1713 Set whether the default state of memory_corruption_check is 1714 on or off. 1715 1716config MATH_EMULATION 1717 bool 1718 depends on MODIFY_LDT_SYSCALL 1719 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1720 help 1721 Linux can emulate a math coprocessor (used for floating point 1722 operations) if you don't have one. 486DX and Pentium processors have 1723 a math coprocessor built in, 486SX and 386 do not, unless you added 1724 a 487DX or 387, respectively. (The messages during boot time can 1725 give you some hints here ["man dmesg"].) Everyone needs either a 1726 coprocessor or this emulation. 1727 1728 If you don't have a math coprocessor, you need to say Y here; if you 1729 say Y here even though you have a coprocessor, the coprocessor will 1730 be used nevertheless. (This behavior can be changed with the kernel 1731 command line option "no387", which comes handy if your coprocessor 1732 is broken. Try "man bootparam" or see the documentation of your boot 1733 loader (lilo or loadlin) about how to pass options to the kernel at 1734 boot time.) This means that it is a good idea to say Y here if you 1735 intend to use this kernel on different machines. 1736 1737 More information about the internals of the Linux math coprocessor 1738 emulation can be found in <file:arch/x86/math-emu/README>. 1739 1740 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1741 kernel, it won't hurt. 1742 1743config MTRR 1744 def_bool y 1745 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1746 help 1747 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1748 the Memory Type Range Registers (MTRRs) may be used to control 1749 processor access to memory ranges. This is most useful if you have 1750 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1751 allows bus write transfers to be combined into a larger transfer 1752 before bursting over the PCI/AGP bus. This can increase performance 1753 of image write operations 2.5 times or more. Saying Y here creates a 1754 /proc/mtrr file which may be used to manipulate your processor's 1755 MTRRs. Typically the X server should use this. 1756 1757 This code has a reasonably generic interface so that similar 1758 control registers on other processors can be easily supported 1759 as well: 1760 1761 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1762 Registers (ARRs) which provide a similar functionality to MTRRs. For 1763 these, the ARRs are used to emulate the MTRRs. 1764 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1765 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1766 write-combining. All of these processors are supported by this code 1767 and it makes sense to say Y here if you have one of them. 1768 1769 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1770 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1771 can lead to all sorts of problems, so it's good to say Y here. 1772 1773 You can safely say Y even if your machine doesn't have MTRRs, you'll 1774 just add about 9 KB to your kernel. 1775 1776 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1777 1778config MTRR_SANITIZER 1779 def_bool y 1780 prompt "MTRR cleanup support" 1781 depends on MTRR 1782 help 1783 Convert MTRR layout from continuous to discrete, so X drivers can 1784 add writeback entries. 1785 1786 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1787 The largest mtrr entry size for a continuous block can be set with 1788 mtrr_chunk_size. 1789 1790 If unsure, say Y. 1791 1792config MTRR_SANITIZER_ENABLE_DEFAULT 1793 int "MTRR cleanup enable value (0-1)" 1794 range 0 1 1795 default "0" 1796 depends on MTRR_SANITIZER 1797 help 1798 Enable mtrr cleanup default value 1799 1800config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1801 int "MTRR cleanup spare reg num (0-7)" 1802 range 0 7 1803 default "1" 1804 depends on MTRR_SANITIZER 1805 help 1806 mtrr cleanup spare entries default, it can be changed via 1807 mtrr_spare_reg_nr=N on the kernel command line. 1808 1809config X86_PAT 1810 def_bool y 1811 prompt "x86 PAT support" if EXPERT 1812 depends on MTRR 1813 help 1814 Use PAT attributes to setup page level cache control. 1815 1816 PATs are the modern equivalents of MTRRs and are much more 1817 flexible than MTRRs. 1818 1819 Say N here if you see bootup problems (boot crash, boot hang, 1820 spontaneous reboots) or a non-working video driver. 1821 1822 If unsure, say Y. 1823 1824config ARCH_USES_PG_UNCACHED 1825 def_bool y 1826 depends on X86_PAT 1827 1828config X86_UMIP 1829 def_bool y 1830 prompt "User Mode Instruction Prevention" if EXPERT 1831 help 1832 User Mode Instruction Prevention (UMIP) is a security feature in 1833 some x86 processors. If enabled, a general protection fault is 1834 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1835 executed in user mode. These instructions unnecessarily expose 1836 information about the hardware state. 1837 1838 The vast majority of applications do not use these instructions. 1839 For the very few that do, software emulation is provided in 1840 specific cases in protected and virtual-8086 modes. Emulated 1841 results are dummy. 1842 1843config CC_HAS_IBT 1844 # GCC >= 9 and binutils >= 2.29 1845 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1846 # Clang/LLVM >= 14 1847 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1848 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1849 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1850 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1851 $(as-instr,endbr64) 1852 1853config X86_CET 1854 def_bool n 1855 help 1856 CET features configured (Shadow stack or IBT) 1857 1858config X86_KERNEL_IBT 1859 prompt "Indirect Branch Tracking" 1860 def_bool y 1861 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1862 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1863 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1864 select OBJTOOL 1865 select X86_CET 1866 help 1867 Build the kernel with support for Indirect Branch Tracking, a 1868 hardware support course-grain forward-edge Control Flow Integrity 1869 protection. It enforces that all indirect calls must land on 1870 an ENDBR instruction, as such, the compiler will instrument the 1871 code with them to make this happen. 1872 1873 In addition to building the kernel with IBT, seal all functions that 1874 are not indirect call targets, avoiding them ever becoming one. 1875 1876 This requires LTO like objtool runs and will slow down the build. It 1877 does significantly reduce the number of ENDBR instructions in the 1878 kernel image. 1879 1880config X86_INTEL_MEMORY_PROTECTION_KEYS 1881 prompt "Memory Protection Keys" 1882 def_bool y 1883 # Note: only available in 64-bit mode 1884 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1885 select ARCH_USES_HIGH_VMA_FLAGS 1886 select ARCH_HAS_PKEYS 1887 help 1888 Memory Protection Keys provides a mechanism for enforcing 1889 page-based protections, but without requiring modification of the 1890 page tables when an application changes protection domains. 1891 1892 For details, see Documentation/core-api/protection-keys.rst 1893 1894 If unsure, say y. 1895 1896choice 1897 prompt "TSX enable mode" 1898 depends on CPU_SUP_INTEL 1899 default X86_INTEL_TSX_MODE_OFF 1900 help 1901 Intel's TSX (Transactional Synchronization Extensions) feature 1902 allows to optimize locking protocols through lock elision which 1903 can lead to a noticeable performance boost. 1904 1905 On the other hand it has been shown that TSX can be exploited 1906 to form side channel attacks (e.g. TAA) and chances are there 1907 will be more of those attacks discovered in the future. 1908 1909 Therefore TSX is not enabled by default (aka tsx=off). An admin 1910 might override this decision by tsx=on the command line parameter. 1911 Even with TSX enabled, the kernel will attempt to enable the best 1912 possible TAA mitigation setting depending on the microcode available 1913 for the particular machine. 1914 1915 This option allows to set the default tsx mode between tsx=on, =off 1916 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1917 details. 1918 1919 Say off if not sure, auto if TSX is in use but it should be used on safe 1920 platforms or on if TSX is in use and the security aspect of tsx is not 1921 relevant. 1922 1923config X86_INTEL_TSX_MODE_OFF 1924 bool "off" 1925 help 1926 TSX is disabled if possible - equals to tsx=off command line parameter. 1927 1928config X86_INTEL_TSX_MODE_ON 1929 bool "on" 1930 help 1931 TSX is always enabled on TSX capable HW - equals the tsx=on command 1932 line parameter. 1933 1934config X86_INTEL_TSX_MODE_AUTO 1935 bool "auto" 1936 help 1937 TSX is enabled on TSX capable HW that is believed to be safe against 1938 side channel attacks- equals the tsx=auto command line parameter. 1939endchoice 1940 1941config X86_SGX 1942 bool "Software Guard eXtensions (SGX)" 1943 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1944 depends on CRYPTO=y 1945 depends on CRYPTO_SHA256=y 1946 select MMU_NOTIFIER 1947 select NUMA_KEEP_MEMINFO if NUMA 1948 select XARRAY_MULTI 1949 help 1950 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1951 that can be used by applications to set aside private regions of code 1952 and data, referred to as enclaves. An enclave's private memory can 1953 only be accessed by code running within the enclave. Accesses from 1954 outside the enclave, including other enclaves, are disallowed by 1955 hardware. 1956 1957 If unsure, say N. 1958 1959config X86_USER_SHADOW_STACK 1960 bool "X86 userspace shadow stack" 1961 depends on AS_WRUSS 1962 depends on X86_64 1963 select ARCH_USES_HIGH_VMA_FLAGS 1964 select X86_CET 1965 help 1966 Shadow stack protection is a hardware feature that detects function 1967 return address corruption. This helps mitigate ROP attacks. 1968 Applications must be enabled to use it, and old userspace does not 1969 get protection "for free". 1970 1971 CPUs supporting shadow stacks were first released in 2020. 1972 1973 See Documentation/arch/x86/shstk.rst for more information. 1974 1975 If unsure, say N. 1976 1977config INTEL_TDX_HOST 1978 bool "Intel Trust Domain Extensions (TDX) host support" 1979 depends on CPU_SUP_INTEL 1980 depends on X86_64 1981 depends on KVM_INTEL 1982 depends on X86_X2APIC 1983 select ARCH_KEEP_MEMBLOCK 1984 depends on CONTIG_ALLOC 1985 depends on !KEXEC_CORE 1986 depends on X86_MCE 1987 help 1988 Intel Trust Domain Extensions (TDX) protects guest VMs from malicious 1989 host and certain physical attacks. This option enables necessary TDX 1990 support in the host kernel to run confidential VMs. 1991 1992 If unsure, say N. 1993 1994config EFI 1995 bool "EFI runtime service support" 1996 depends on ACPI 1997 select UCS2_STRING 1998 select EFI_RUNTIME_WRAPPERS 1999 select ARCH_USE_MEMREMAP_PROT 2000 select EFI_RUNTIME_MAP if KEXEC_CORE 2001 help 2002 This enables the kernel to use EFI runtime services that are 2003 available (such as the EFI variable services). 2004 2005 This option is only useful on systems that have EFI firmware. 2006 In addition, you should use the latest ELILO loader available 2007 at <http://elilo.sourceforge.net> in order to take advantage 2008 of EFI runtime services. However, even with this option, the 2009 resultant kernel should continue to boot on existing non-EFI 2010 platforms. 2011 2012config EFI_STUB 2013 bool "EFI stub support" 2014 depends on EFI 2015 select RELOCATABLE 2016 help 2017 This kernel feature allows a bzImage to be loaded directly 2018 by EFI firmware without the use of a bootloader. 2019 2020 See Documentation/admin-guide/efi-stub.rst for more information. 2021 2022config EFI_HANDOVER_PROTOCOL 2023 bool "EFI handover protocol (DEPRECATED)" 2024 depends on EFI_STUB 2025 default y 2026 help 2027 Select this in order to include support for the deprecated EFI 2028 handover protocol, which defines alternative entry points into the 2029 EFI stub. This is a practice that has no basis in the UEFI 2030 specification, and requires a priori knowledge on the part of the 2031 bootloader about Linux/x86 specific ways of passing the command line 2032 and initrd, and where in memory those assets may be loaded. 2033 2034 If in doubt, say Y. Even though the corresponding support is not 2035 present in upstream GRUB or other bootloaders, most distros build 2036 GRUB with numerous downstream patches applied, and may rely on the 2037 handover protocol as as result. 2038 2039config EFI_MIXED 2040 bool "EFI mixed-mode support" 2041 depends on EFI_STUB && X86_64 2042 help 2043 Enabling this feature allows a 64-bit kernel to be booted 2044 on a 32-bit firmware, provided that your CPU supports 64-bit 2045 mode. 2046 2047 Note that it is not possible to boot a mixed-mode enabled 2048 kernel via the EFI boot stub - a bootloader that supports 2049 the EFI handover protocol must be used. 2050 2051 If unsure, say N. 2052 2053config EFI_FAKE_MEMMAP 2054 bool "Enable EFI fake memory map" 2055 depends on EFI 2056 help 2057 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2058 this parameter, you can add arbitrary attribute to specific memory 2059 range by updating original (firmware provided) EFI memmap. This is 2060 useful for debugging of EFI memmap related feature, e.g., Address 2061 Range Mirroring feature. 2062 2063config EFI_MAX_FAKE_MEM 2064 int "maximum allowable number of ranges in efi_fake_mem boot option" 2065 depends on EFI_FAKE_MEMMAP 2066 range 1 128 2067 default 8 2068 help 2069 Maximum allowable number of ranges in efi_fake_mem boot option. 2070 Ranges can be set up to this value using comma-separated list. 2071 The default value is 8. 2072 2073config EFI_RUNTIME_MAP 2074 bool "Export EFI runtime maps to sysfs" if EXPERT 2075 depends on EFI 2076 help 2077 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2078 That memory map is required by the 2nd kernel to set up EFI virtual 2079 mappings after kexec, but can also be used for debugging purposes. 2080 2081 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2082 2083source "kernel/Kconfig.hz" 2084 2085config ARCH_SUPPORTS_KEXEC 2086 def_bool y 2087 2088config ARCH_SUPPORTS_KEXEC_FILE 2089 def_bool X86_64 2090 2091config ARCH_SELECTS_KEXEC_FILE 2092 def_bool y 2093 depends on KEXEC_FILE 2094 select HAVE_IMA_KEXEC if IMA 2095 2096config ARCH_SUPPORTS_KEXEC_PURGATORY 2097 def_bool y 2098 2099config ARCH_SUPPORTS_KEXEC_SIG 2100 def_bool y 2101 2102config ARCH_SUPPORTS_KEXEC_SIG_FORCE 2103 def_bool y 2104 2105config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 2106 def_bool y 2107 2108config ARCH_SUPPORTS_KEXEC_JUMP 2109 def_bool y 2110 2111config ARCH_SUPPORTS_CRASH_DUMP 2112 def_bool X86_64 || (X86_32 && HIGHMEM) 2113 2114config ARCH_SUPPORTS_CRASH_HOTPLUG 2115 def_bool y 2116 2117config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION 2118 def_bool CRASH_CORE 2119 2120config PHYSICAL_START 2121 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2122 default "0x1000000" 2123 help 2124 This gives the physical address where the kernel is loaded. 2125 2126 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2127 bzImage will decompress itself to above physical address and 2128 run from there. Otherwise, bzImage will run from the address where 2129 it has been loaded by the boot loader and will ignore above physical 2130 address. 2131 2132 In normal kdump cases one does not have to set/change this option 2133 as now bzImage can be compiled as a completely relocatable image 2134 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2135 address. This option is mainly useful for the folks who don't want 2136 to use a bzImage for capturing the crash dump and want to use a 2137 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2138 to be specifically compiled to run from a specific memory area 2139 (normally a reserved region) and this option comes handy. 2140 2141 So if you are using bzImage for capturing the crash dump, 2142 leave the value here unchanged to 0x1000000 and set 2143 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2144 for capturing the crash dump change this value to start of 2145 the reserved region. In other words, it can be set based on 2146 the "X" value as specified in the "crashkernel=YM@XM" 2147 command line boot parameter passed to the panic-ed 2148 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2149 for more details about crash dumps. 2150 2151 Usage of bzImage for capturing the crash dump is recommended as 2152 one does not have to build two kernels. Same kernel can be used 2153 as production kernel and capture kernel. Above option should have 2154 gone away after relocatable bzImage support is introduced. But it 2155 is present because there are users out there who continue to use 2156 vmlinux for dump capture. This option should go away down the 2157 line. 2158 2159 Don't change this unless you know what you are doing. 2160 2161config RELOCATABLE 2162 bool "Build a relocatable kernel" 2163 default y 2164 help 2165 This builds a kernel image that retains relocation information 2166 so it can be loaded someplace besides the default 1MB. 2167 The relocations tend to make the kernel binary about 10% larger, 2168 but are discarded at runtime. 2169 2170 One use is for the kexec on panic case where the recovery kernel 2171 must live at a different physical address than the primary 2172 kernel. 2173 2174 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2175 it has been loaded at and the compile time physical address 2176 (CONFIG_PHYSICAL_START) is used as the minimum location. 2177 2178config RANDOMIZE_BASE 2179 bool "Randomize the address of the kernel image (KASLR)" 2180 depends on RELOCATABLE 2181 default y 2182 help 2183 In support of Kernel Address Space Layout Randomization (KASLR), 2184 this randomizes the physical address at which the kernel image 2185 is decompressed and the virtual address where the kernel 2186 image is mapped, as a security feature that deters exploit 2187 attempts relying on knowledge of the location of kernel 2188 code internals. 2189 2190 On 64-bit, the kernel physical and virtual addresses are 2191 randomized separately. The physical address will be anywhere 2192 between 16MB and the top of physical memory (up to 64TB). The 2193 virtual address will be randomized from 16MB up to 1GB (9 bits 2194 of entropy). Note that this also reduces the memory space 2195 available to kernel modules from 1.5GB to 1GB. 2196 2197 On 32-bit, the kernel physical and virtual addresses are 2198 randomized together. They will be randomized from 16MB up to 2199 512MB (8 bits of entropy). 2200 2201 Entropy is generated using the RDRAND instruction if it is 2202 supported. If RDTSC is supported, its value is mixed into 2203 the entropy pool as well. If neither RDRAND nor RDTSC are 2204 supported, then entropy is read from the i8254 timer. The 2205 usable entropy is limited by the kernel being built using 2206 2GB addressing, and that PHYSICAL_ALIGN must be at a 2207 minimum of 2MB. As a result, only 10 bits of entropy are 2208 theoretically possible, but the implementations are further 2209 limited due to memory layouts. 2210 2211 If unsure, say Y. 2212 2213# Relocation on x86 needs some additional build support 2214config X86_NEED_RELOCS 2215 def_bool y 2216 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2217 2218config PHYSICAL_ALIGN 2219 hex "Alignment value to which kernel should be aligned" 2220 default "0x200000" 2221 range 0x2000 0x1000000 if X86_32 2222 range 0x200000 0x1000000 if X86_64 2223 help 2224 This value puts the alignment restrictions on physical address 2225 where kernel is loaded and run from. Kernel is compiled for an 2226 address which meets above alignment restriction. 2227 2228 If bootloader loads the kernel at a non-aligned address and 2229 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2230 address aligned to above value and run from there. 2231 2232 If bootloader loads the kernel at a non-aligned address and 2233 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2234 load address and decompress itself to the address it has been 2235 compiled for and run from there. The address for which kernel is 2236 compiled already meets above alignment restrictions. Hence the 2237 end result is that kernel runs from a physical address meeting 2238 above alignment restrictions. 2239 2240 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2241 this value must be a multiple of 0x200000. 2242 2243 Don't change this unless you know what you are doing. 2244 2245config DYNAMIC_MEMORY_LAYOUT 2246 bool 2247 help 2248 This option makes base addresses of vmalloc and vmemmap as well as 2249 __PAGE_OFFSET movable during boot. 2250 2251config RANDOMIZE_MEMORY 2252 bool "Randomize the kernel memory sections" 2253 depends on X86_64 2254 depends on RANDOMIZE_BASE 2255 select DYNAMIC_MEMORY_LAYOUT 2256 default RANDOMIZE_BASE 2257 help 2258 Randomizes the base virtual address of kernel memory sections 2259 (physical memory mapping, vmalloc & vmemmap). This security feature 2260 makes exploits relying on predictable memory locations less reliable. 2261 2262 The order of allocations remains unchanged. Entropy is generated in 2263 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2264 configuration have in average 30,000 different possible virtual 2265 addresses for each memory section. 2266 2267 If unsure, say Y. 2268 2269config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2270 hex "Physical memory mapping padding" if EXPERT 2271 depends on RANDOMIZE_MEMORY 2272 default "0xa" if MEMORY_HOTPLUG 2273 default "0x0" 2274 range 0x1 0x40 if MEMORY_HOTPLUG 2275 range 0x0 0x40 2276 help 2277 Define the padding in terabytes added to the existing physical 2278 memory size during kernel memory randomization. It is useful 2279 for memory hotplug support but reduces the entropy available for 2280 address randomization. 2281 2282 If unsure, leave at the default value. 2283 2284config ADDRESS_MASKING 2285 bool "Linear Address Masking support" 2286 depends on X86_64 2287 help 2288 Linear Address Masking (LAM) modifies the checking that is applied 2289 to 64-bit linear addresses, allowing software to use of the 2290 untranslated address bits for metadata. 2291 2292 The capability can be used for efficient address sanitizers (ASAN) 2293 implementation and for optimizations in JITs. 2294 2295config HOTPLUG_CPU 2296 def_bool y 2297 depends on SMP 2298 2299config COMPAT_VDSO 2300 def_bool n 2301 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2302 depends on COMPAT_32 2303 help 2304 Certain buggy versions of glibc will crash if they are 2305 presented with a 32-bit vDSO that is not mapped at the address 2306 indicated in its segment table. 2307 2308 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2309 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2310 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2311 the only released version with the bug, but OpenSUSE 9 2312 contains a buggy "glibc 2.3.2". 2313 2314 The symptom of the bug is that everything crashes on startup, saying: 2315 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2316 2317 Saying Y here changes the default value of the vdso32 boot 2318 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2319 This works around the glibc bug but hurts performance. 2320 2321 If unsure, say N: if you are compiling your own kernel, you 2322 are unlikely to be using a buggy version of glibc. 2323 2324choice 2325 prompt "vsyscall table for legacy applications" 2326 depends on X86_64 2327 default LEGACY_VSYSCALL_XONLY 2328 help 2329 Legacy user code that does not know how to find the vDSO expects 2330 to be able to issue three syscalls by calling fixed addresses in 2331 kernel space. Since this location is not randomized with ASLR, 2332 it can be used to assist security vulnerability exploitation. 2333 2334 This setting can be changed at boot time via the kernel command 2335 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2336 is deprecated and can only be enabled using the kernel command 2337 line. 2338 2339 On a system with recent enough glibc (2.14 or newer) and no 2340 static binaries, you can say None without a performance penalty 2341 to improve security. 2342 2343 If unsure, select "Emulate execution only". 2344 2345 config LEGACY_VSYSCALL_XONLY 2346 bool "Emulate execution only" 2347 help 2348 The kernel traps and emulates calls into the fixed vsyscall 2349 address mapping and does not allow reads. This 2350 configuration is recommended when userspace might use the 2351 legacy vsyscall area but support for legacy binary 2352 instrumentation of legacy code is not needed. It mitigates 2353 certain uses of the vsyscall area as an ASLR-bypassing 2354 buffer. 2355 2356 config LEGACY_VSYSCALL_NONE 2357 bool "None" 2358 help 2359 There will be no vsyscall mapping at all. This will 2360 eliminate any risk of ASLR bypass due to the vsyscall 2361 fixed address mapping. Attempts to use the vsyscalls 2362 will be reported to dmesg, so that either old or 2363 malicious userspace programs can be identified. 2364 2365endchoice 2366 2367config CMDLINE_BOOL 2368 bool "Built-in kernel command line" 2369 help 2370 Allow for specifying boot arguments to the kernel at 2371 build time. On some systems (e.g. embedded ones), it is 2372 necessary or convenient to provide some or all of the 2373 kernel boot arguments with the kernel itself (that is, 2374 to not rely on the boot loader to provide them.) 2375 2376 To compile command line arguments into the kernel, 2377 set this option to 'Y', then fill in the 2378 boot arguments in CONFIG_CMDLINE. 2379 2380 Systems with fully functional boot loaders (i.e. non-embedded) 2381 should leave this option set to 'N'. 2382 2383config CMDLINE 2384 string "Built-in kernel command string" 2385 depends on CMDLINE_BOOL 2386 default "" 2387 help 2388 Enter arguments here that should be compiled into the kernel 2389 image and used at boot time. If the boot loader provides a 2390 command line at boot time, it is appended to this string to 2391 form the full kernel command line, when the system boots. 2392 2393 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2394 change this behavior. 2395 2396 In most cases, the command line (whether built-in or provided 2397 by the boot loader) should specify the device for the root 2398 file system. 2399 2400config CMDLINE_OVERRIDE 2401 bool "Built-in command line overrides boot loader arguments" 2402 depends on CMDLINE_BOOL && CMDLINE != "" 2403 help 2404 Set this option to 'Y' to have the kernel ignore the boot loader 2405 command line, and use ONLY the built-in command line. 2406 2407 This is used to work around broken boot loaders. This should 2408 be set to 'N' under normal conditions. 2409 2410config MODIFY_LDT_SYSCALL 2411 bool "Enable the LDT (local descriptor table)" if EXPERT 2412 default y 2413 help 2414 Linux can allow user programs to install a per-process x86 2415 Local Descriptor Table (LDT) using the modify_ldt(2) system 2416 call. This is required to run 16-bit or segmented code such as 2417 DOSEMU or some Wine programs. It is also used by some very old 2418 threading libraries. 2419 2420 Enabling this feature adds a small amount of overhead to 2421 context switches and increases the low-level kernel attack 2422 surface. Disabling it removes the modify_ldt(2) system call. 2423 2424 Saying 'N' here may make sense for embedded or server kernels. 2425 2426config STRICT_SIGALTSTACK_SIZE 2427 bool "Enforce strict size checking for sigaltstack" 2428 depends on DYNAMIC_SIGFRAME 2429 help 2430 For historical reasons MINSIGSTKSZ is a constant which became 2431 already too small with AVX512 support. Add a mechanism to 2432 enforce strict checking of the sigaltstack size against the 2433 real size of the FPU frame. This option enables the check 2434 by default. It can also be controlled via the kernel command 2435 line option 'strict_sas_size' independent of this config 2436 switch. Enabling it might break existing applications which 2437 allocate a too small sigaltstack but 'work' because they 2438 never get a signal delivered. 2439 2440 Say 'N' unless you want to really enforce this check. 2441 2442source "kernel/livepatch/Kconfig" 2443 2444endmenu 2445 2446config CC_HAS_SLS 2447 def_bool $(cc-option,-mharden-sls=all) 2448 2449config CC_HAS_RETURN_THUNK 2450 def_bool $(cc-option,-mfunction-return=thunk-extern) 2451 2452config CC_HAS_ENTRY_PADDING 2453 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2454 2455config FUNCTION_PADDING_CFI 2456 int 2457 default 59 if FUNCTION_ALIGNMENT_64B 2458 default 27 if FUNCTION_ALIGNMENT_32B 2459 default 11 if FUNCTION_ALIGNMENT_16B 2460 default 3 if FUNCTION_ALIGNMENT_8B 2461 default 0 2462 2463# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2464# except Kconfig can't do arithmetic :/ 2465config FUNCTION_PADDING_BYTES 2466 int 2467 default FUNCTION_PADDING_CFI if CFI_CLANG 2468 default FUNCTION_ALIGNMENT 2469 2470config CALL_PADDING 2471 def_bool n 2472 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2473 select FUNCTION_ALIGNMENT_16B 2474 2475config FINEIBT 2476 def_bool y 2477 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2478 select CALL_PADDING 2479 2480config HAVE_CALL_THUNKS 2481 def_bool y 2482 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2483 2484config CALL_THUNKS 2485 def_bool n 2486 select CALL_PADDING 2487 2488config PREFIX_SYMBOLS 2489 def_bool y 2490 depends on CALL_PADDING && !CFI_CLANG 2491 2492menuconfig SPECULATION_MITIGATIONS 2493 bool "Mitigations for speculative execution vulnerabilities" 2494 default y 2495 help 2496 Say Y here to enable options which enable mitigations for 2497 speculative execution hardware vulnerabilities. 2498 2499 If you say N, all mitigations will be disabled. You really 2500 should know what you are doing to say so. 2501 2502if SPECULATION_MITIGATIONS 2503 2504config PAGE_TABLE_ISOLATION 2505 bool "Remove the kernel mapping in user mode" 2506 default y 2507 depends on (X86_64 || X86_PAE) 2508 help 2509 This feature reduces the number of hardware side channels by 2510 ensuring that the majority of kernel addresses are not mapped 2511 into userspace. 2512 2513 See Documentation/arch/x86/pti.rst for more details. 2514 2515config RETPOLINE 2516 bool "Avoid speculative indirect branches in kernel" 2517 select OBJTOOL if HAVE_OBJTOOL 2518 default y 2519 help 2520 Compile kernel with the retpoline compiler options to guard against 2521 kernel-to-user data leaks by avoiding speculative indirect 2522 branches. Requires a compiler with -mindirect-branch=thunk-extern 2523 support for full protection. The kernel may run slower. 2524 2525config RETHUNK 2526 bool "Enable return-thunks" 2527 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2528 select OBJTOOL if HAVE_OBJTOOL 2529 default y if X86_64 2530 help 2531 Compile the kernel with the return-thunks compiler option to guard 2532 against kernel-to-user data leaks by avoiding return speculation. 2533 Requires a compiler with -mfunction-return=thunk-extern 2534 support for full protection. The kernel may run slower. 2535 2536config CPU_UNRET_ENTRY 2537 bool "Enable UNRET on kernel entry" 2538 depends on CPU_SUP_AMD && RETHUNK && X86_64 2539 default y 2540 help 2541 Compile the kernel with support for the retbleed=unret mitigation. 2542 2543config CALL_DEPTH_TRACKING 2544 bool "Mitigate RSB underflow with call depth tracking" 2545 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2546 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2547 select CALL_THUNKS 2548 default y 2549 help 2550 Compile the kernel with call depth tracking to mitigate the Intel 2551 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2552 mitigation is off by default and needs to be enabled on the 2553 kernel command line via the retbleed=stuff option. For 2554 non-affected systems the overhead of this option is marginal as 2555 the call depth tracking is using run-time generated call thunks 2556 in a compiler generated padding area and call patching. This 2557 increases text size by ~5%. For non affected systems this space 2558 is unused. On affected SKL systems this results in a significant 2559 performance gain over the IBRS mitigation. 2560 2561config CALL_THUNKS_DEBUG 2562 bool "Enable call thunks and call depth tracking debugging" 2563 depends on CALL_DEPTH_TRACKING 2564 select FUNCTION_ALIGNMENT_32B 2565 default n 2566 help 2567 Enable call/ret counters for imbalance detection and build in 2568 a noisy dmesg about callthunks generation and call patching for 2569 trouble shooting. The debug prints need to be enabled on the 2570 kernel command line with 'debug-callthunks'. 2571 Only enable this when you are debugging call thunks as this 2572 creates a noticeable runtime overhead. If unsure say N. 2573 2574config CPU_IBPB_ENTRY 2575 bool "Enable IBPB on kernel entry" 2576 depends on CPU_SUP_AMD && X86_64 2577 default y 2578 help 2579 Compile the kernel with support for the retbleed=ibpb mitigation. 2580 2581config CPU_IBRS_ENTRY 2582 bool "Enable IBRS on kernel entry" 2583 depends on CPU_SUP_INTEL && X86_64 2584 default y 2585 help 2586 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2587 This mitigates both spectre_v2 and retbleed at great cost to 2588 performance. 2589 2590config CPU_SRSO 2591 bool "Mitigate speculative RAS overflow on AMD" 2592 depends on CPU_SUP_AMD && X86_64 && RETHUNK 2593 default y 2594 help 2595 Enable the SRSO mitigation needed on AMD Zen1-4 machines. 2596 2597config SLS 2598 bool "Mitigate Straight-Line-Speculation" 2599 depends on CC_HAS_SLS && X86_64 2600 select OBJTOOL if HAVE_OBJTOOL 2601 default n 2602 help 2603 Compile the kernel with straight-line-speculation options to guard 2604 against straight line speculation. The kernel image might be slightly 2605 larger. 2606 2607config GDS_FORCE_MITIGATION 2608 bool "Force GDS Mitigation" 2609 depends on CPU_SUP_INTEL 2610 default n 2611 help 2612 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2613 unprivileged speculative access to data which was previously stored in 2614 vector registers. 2615 2616 This option is equivalent to setting gather_data_sampling=force on the 2617 command line. The microcode mitigation is used if present, otherwise 2618 AVX is disabled as a mitigation. On affected systems that are missing 2619 the microcode any userspace code that unconditionally uses AVX will 2620 break with this option set. 2621 2622 Setting this option on systems not vulnerable to GDS has no effect. 2623 2624 If in doubt, say N. 2625 2626endif 2627 2628config ARCH_HAS_ADD_PAGES 2629 def_bool y 2630 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2631 2632menu "Power management and ACPI options" 2633 2634config ARCH_HIBERNATION_HEADER 2635 def_bool y 2636 depends on HIBERNATION 2637 2638source "kernel/power/Kconfig" 2639 2640source "drivers/acpi/Kconfig" 2641 2642config X86_APM_BOOT 2643 def_bool y 2644 depends on APM 2645 2646menuconfig APM 2647 tristate "APM (Advanced Power Management) BIOS support" 2648 depends on X86_32 && PM_SLEEP 2649 help 2650 APM is a BIOS specification for saving power using several different 2651 techniques. This is mostly useful for battery powered laptops with 2652 APM compliant BIOSes. If you say Y here, the system time will be 2653 reset after a RESUME operation, the /proc/apm device will provide 2654 battery status information, and user-space programs will receive 2655 notification of APM "events" (e.g. battery status change). 2656 2657 If you select "Y" here, you can disable actual use of the APM 2658 BIOS by passing the "apm=off" option to the kernel at boot time. 2659 2660 Note that the APM support is almost completely disabled for 2661 machines with more than one CPU. 2662 2663 In order to use APM, you will need supporting software. For location 2664 and more information, read <file:Documentation/power/apm-acpi.rst> 2665 and the Battery Powered Linux mini-HOWTO, available from 2666 <http://www.tldp.org/docs.html#howto>. 2667 2668 This driver does not spin down disk drives (see the hdparm(8) 2669 manpage ("man 8 hdparm") for that), and it doesn't turn off 2670 VESA-compliant "green" monitors. 2671 2672 This driver does not support the TI 4000M TravelMate and the ACER 2673 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2674 desktop machines also don't have compliant BIOSes, and this driver 2675 may cause those machines to panic during the boot phase. 2676 2677 Generally, if you don't have a battery in your machine, there isn't 2678 much point in using this driver and you should say N. If you get 2679 random kernel OOPSes or reboots that don't seem to be related to 2680 anything, try disabling/enabling this option (or disabling/enabling 2681 APM in your BIOS). 2682 2683 Some other things you should try when experiencing seemingly random, 2684 "weird" problems: 2685 2686 1) make sure that you have enough swap space and that it is 2687 enabled. 2688 2) pass the "idle=poll" option to the kernel 2689 3) switch on floating point emulation in the kernel and pass 2690 the "no387" option to the kernel 2691 4) pass the "floppy=nodma" option to the kernel 2692 5) pass the "mem=4M" option to the kernel (thereby disabling 2693 all but the first 4 MB of RAM) 2694 6) make sure that the CPU is not over clocked. 2695 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2696 8) disable the cache from your BIOS settings 2697 9) install a fan for the video card or exchange video RAM 2698 10) install a better fan for the CPU 2699 11) exchange RAM chips 2700 12) exchange the motherboard. 2701 2702 To compile this driver as a module, choose M here: the 2703 module will be called apm. 2704 2705if APM 2706 2707config APM_IGNORE_USER_SUSPEND 2708 bool "Ignore USER SUSPEND" 2709 help 2710 This option will ignore USER SUSPEND requests. On machines with a 2711 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2712 series notebooks, it is necessary to say Y because of a BIOS bug. 2713 2714config APM_DO_ENABLE 2715 bool "Enable PM at boot time" 2716 help 2717 Enable APM features at boot time. From page 36 of the APM BIOS 2718 specification: "When disabled, the APM BIOS does not automatically 2719 power manage devices, enter the Standby State, enter the Suspend 2720 State, or take power saving steps in response to CPU Idle calls." 2721 This driver will make CPU Idle calls when Linux is idle (unless this 2722 feature is turned off -- see "Do CPU IDLE calls", below). This 2723 should always save battery power, but more complicated APM features 2724 will be dependent on your BIOS implementation. You may need to turn 2725 this option off if your computer hangs at boot time when using APM 2726 support, or if it beeps continuously instead of suspending. Turn 2727 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2728 T400CDT. This is off by default since most machines do fine without 2729 this feature. 2730 2731config APM_CPU_IDLE 2732 depends on CPU_IDLE 2733 bool "Make CPU Idle calls when idle" 2734 help 2735 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2736 On some machines, this can activate improved power savings, such as 2737 a slowed CPU clock rate, when the machine is idle. These idle calls 2738 are made after the idle loop has run for some length of time (e.g., 2739 333 mS). On some machines, this will cause a hang at boot time or 2740 whenever the CPU becomes idle. (On machines with more than one CPU, 2741 this option does nothing.) 2742 2743config APM_DISPLAY_BLANK 2744 bool "Enable console blanking using APM" 2745 help 2746 Enable console blanking using the APM. Some laptops can use this to 2747 turn off the LCD backlight when the screen blanker of the Linux 2748 virtual console blanks the screen. Note that this is only used by 2749 the virtual console screen blanker, and won't turn off the backlight 2750 when using the X Window system. This also doesn't have anything to 2751 do with your VESA-compliant power-saving monitor. Further, this 2752 option doesn't work for all laptops -- it might not turn off your 2753 backlight at all, or it might print a lot of errors to the console, 2754 especially if you are using gpm. 2755 2756config APM_ALLOW_INTS 2757 bool "Allow interrupts during APM BIOS calls" 2758 help 2759 Normally we disable external interrupts while we are making calls to 2760 the APM BIOS as a measure to lessen the effects of a badly behaving 2761 BIOS implementation. The BIOS should reenable interrupts if it 2762 needs to. Unfortunately, some BIOSes do not -- especially those in 2763 many of the newer IBM Thinkpads. If you experience hangs when you 2764 suspend, try setting this to Y. Otherwise, say N. 2765 2766endif # APM 2767 2768source "drivers/cpufreq/Kconfig" 2769 2770source "drivers/cpuidle/Kconfig" 2771 2772source "drivers/idle/Kconfig" 2773 2774endmenu 2775 2776menu "Bus options (PCI etc.)" 2777 2778choice 2779 prompt "PCI access mode" 2780 depends on X86_32 && PCI 2781 default PCI_GOANY 2782 help 2783 On PCI systems, the BIOS can be used to detect the PCI devices and 2784 determine their configuration. However, some old PCI motherboards 2785 have BIOS bugs and may crash if this is done. Also, some embedded 2786 PCI-based systems don't have any BIOS at all. Linux can also try to 2787 detect the PCI hardware directly without using the BIOS. 2788 2789 With this option, you can specify how Linux should detect the 2790 PCI devices. If you choose "BIOS", the BIOS will be used, 2791 if you choose "Direct", the BIOS won't be used, and if you 2792 choose "MMConfig", then PCI Express MMCONFIG will be used. 2793 If you choose "Any", the kernel will try MMCONFIG, then the 2794 direct access method and falls back to the BIOS if that doesn't 2795 work. If unsure, go with the default, which is "Any". 2796 2797config PCI_GOBIOS 2798 bool "BIOS" 2799 2800config PCI_GOMMCONFIG 2801 bool "MMConfig" 2802 2803config PCI_GODIRECT 2804 bool "Direct" 2805 2806config PCI_GOOLPC 2807 bool "OLPC XO-1" 2808 depends on OLPC 2809 2810config PCI_GOANY 2811 bool "Any" 2812 2813endchoice 2814 2815config PCI_BIOS 2816 def_bool y 2817 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2818 2819# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2820config PCI_DIRECT 2821 def_bool y 2822 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2823 2824config PCI_MMCONFIG 2825 bool "Support mmconfig PCI config space access" if X86_64 2826 default y 2827 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2828 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2829 2830config PCI_OLPC 2831 def_bool y 2832 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2833 2834config PCI_XEN 2835 def_bool y 2836 depends on PCI && XEN 2837 2838config MMCONF_FAM10H 2839 def_bool y 2840 depends on X86_64 && PCI_MMCONFIG && ACPI 2841 2842config PCI_CNB20LE_QUIRK 2843 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2844 depends on PCI 2845 help 2846 Read the PCI windows out of the CNB20LE host bridge. This allows 2847 PCI hotplug to work on systems with the CNB20LE chipset which do 2848 not have ACPI. 2849 2850 There's no public spec for this chipset, and this functionality 2851 is known to be incomplete. 2852 2853 You should say N unless you know you need this. 2854 2855config ISA_BUS 2856 bool "ISA bus support on modern systems" if EXPERT 2857 help 2858 Expose ISA bus device drivers and options available for selection and 2859 configuration. Enable this option if your target machine has an ISA 2860 bus. ISA is an older system, displaced by PCI and newer bus 2861 architectures -- if your target machine is modern, it probably does 2862 not have an ISA bus. 2863 2864 If unsure, say N. 2865 2866# x86_64 have no ISA slots, but can have ISA-style DMA. 2867config ISA_DMA_API 2868 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2869 default y 2870 help 2871 Enables ISA-style DMA support for devices requiring such controllers. 2872 If unsure, say Y. 2873 2874if X86_32 2875 2876config ISA 2877 bool "ISA support" 2878 help 2879 Find out whether you have ISA slots on your motherboard. ISA is the 2880 name of a bus system, i.e. the way the CPU talks to the other stuff 2881 inside your box. Other bus systems are PCI, EISA, MicroChannel 2882 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2883 newer boards don't support it. If you have ISA, say Y, otherwise N. 2884 2885config SCx200 2886 tristate "NatSemi SCx200 support" 2887 help 2888 This provides basic support for National Semiconductor's 2889 (now AMD's) Geode processors. The driver probes for the 2890 PCI-IDs of several on-chip devices, so its a good dependency 2891 for other scx200_* drivers. 2892 2893 If compiled as a module, the driver is named scx200. 2894 2895config SCx200HR_TIMER 2896 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2897 depends on SCx200 2898 default y 2899 help 2900 This driver provides a clocksource built upon the on-chip 2901 27MHz high-resolution timer. Its also a workaround for 2902 NSC Geode SC-1100's buggy TSC, which loses time when the 2903 processor goes idle (as is done by the scheduler). The 2904 other workaround is idle=poll boot option. 2905 2906config OLPC 2907 bool "One Laptop Per Child support" 2908 depends on !X86_PAE 2909 select GPIOLIB 2910 select OF 2911 select OF_PROMTREE 2912 select IRQ_DOMAIN 2913 select OLPC_EC 2914 help 2915 Add support for detecting the unique features of the OLPC 2916 XO hardware. 2917 2918config OLPC_XO1_PM 2919 bool "OLPC XO-1 Power Management" 2920 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2921 help 2922 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2923 2924config OLPC_XO1_RTC 2925 bool "OLPC XO-1 Real Time Clock" 2926 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2927 help 2928 Add support for the XO-1 real time clock, which can be used as a 2929 programmable wakeup source. 2930 2931config OLPC_XO1_SCI 2932 bool "OLPC XO-1 SCI extras" 2933 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2934 depends on INPUT=y 2935 select POWER_SUPPLY 2936 help 2937 Add support for SCI-based features of the OLPC XO-1 laptop: 2938 - EC-driven system wakeups 2939 - Power button 2940 - Ebook switch 2941 - Lid switch 2942 - AC adapter status updates 2943 - Battery status updates 2944 2945config OLPC_XO15_SCI 2946 bool "OLPC XO-1.5 SCI extras" 2947 depends on OLPC && ACPI 2948 select POWER_SUPPLY 2949 help 2950 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2951 - EC-driven system wakeups 2952 - AC adapter status updates 2953 - Battery status updates 2954 2955config ALIX 2956 bool "PCEngines ALIX System Support (LED setup)" 2957 select GPIOLIB 2958 help 2959 This option enables system support for the PCEngines ALIX. 2960 At present this just sets up LEDs for GPIO control on 2961 ALIX2/3/6 boards. However, other system specific setup should 2962 get added here. 2963 2964 Note: You must still enable the drivers for GPIO and LED support 2965 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2966 2967 Note: You have to set alix.force=1 for boards with Award BIOS. 2968 2969config NET5501 2970 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2971 select GPIOLIB 2972 help 2973 This option enables system support for the Soekris Engineering net5501. 2974 2975config GEOS 2976 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2977 select GPIOLIB 2978 depends on DMI 2979 help 2980 This option enables system support for the Traverse Technologies GEOS. 2981 2982config TS5500 2983 bool "Technologic Systems TS-5500 platform support" 2984 depends on MELAN 2985 select CHECK_SIGNATURE 2986 select NEW_LEDS 2987 select LEDS_CLASS 2988 help 2989 This option enables system support for the Technologic Systems TS-5500. 2990 2991endif # X86_32 2992 2993config AMD_NB 2994 def_bool y 2995 depends on CPU_SUP_AMD && PCI 2996 2997endmenu 2998 2999menu "Binary Emulations" 3000 3001config IA32_EMULATION 3002 bool "IA32 Emulation" 3003 depends on X86_64 3004 select ARCH_WANT_OLD_COMPAT_IPC 3005 select BINFMT_ELF 3006 select COMPAT_OLD_SIGACTION 3007 help 3008 Include code to run legacy 32-bit programs under a 3009 64-bit kernel. You should likely turn this on, unless you're 3010 100% sure that you don't have any 32-bit programs left. 3011 3012config IA32_EMULATION_DEFAULT_DISABLED 3013 bool "IA32 emulation disabled by default" 3014 default n 3015 depends on IA32_EMULATION 3016 help 3017 Make IA32 emulation disabled by default. This prevents loading 32-bit 3018 processes and access to 32-bit syscalls. If unsure, leave it to its 3019 default value. 3020 3021config X86_X32_ABI 3022 bool "x32 ABI for 64-bit mode" 3023 depends on X86_64 3024 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3025 # compressed debug sections to x86_x32 properly: 3026 # https://github.com/ClangBuiltLinux/linux/issues/514 3027 # https://github.com/ClangBuiltLinux/linux/issues/1141 3028 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3029 help 3030 Include code to run binaries for the x32 native 32-bit ABI 3031 for 64-bit processors. An x32 process gets access to the 3032 full 64-bit register file and wide data path while leaving 3033 pointers at 32 bits for smaller memory footprint. 3034 3035config COMPAT_32 3036 def_bool y 3037 depends on IA32_EMULATION || X86_32 3038 select HAVE_UID16 3039 select OLD_SIGSUSPEND3 3040 3041config COMPAT 3042 def_bool y 3043 depends on IA32_EMULATION || X86_X32_ABI 3044 3045config COMPAT_FOR_U64_ALIGNMENT 3046 def_bool y 3047 depends on COMPAT 3048 3049endmenu 3050 3051config HAVE_ATOMIC_IOMAP 3052 def_bool y 3053 depends on X86_32 3054 3055source "arch/x86/kvm/Kconfig" 3056 3057source "arch/x86/Kconfig.assembler" 3058