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