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 ARCH_USE_CMPXCHG_LOCKREF 32 select HAVE_ARCH_SOFT_DIRTY 33 select MODULES_USE_ELF_RELA 34 select NEED_DMA_MAP_STATE 35 select SWIOTLB 36 select ARCH_HAS_ELFCORE_COMPAT 37 select ZONE_DMA32 38 39config FORCE_DYNAMIC_FTRACE 40 def_bool y 41 depends on X86_32 42 depends on FUNCTION_TRACER 43 select DYNAMIC_FTRACE 44 help 45 We keep the static function tracing (!DYNAMIC_FTRACE) around 46 in order to test the non static function tracing in the 47 generic code, as other architectures still use it. But we 48 only need to keep it around for x86_64. No need to keep it 49 for x86_32. For x86_32, force DYNAMIC_FTRACE. 50# 51# Arch settings 52# 53# ( Note that options that are marked 'if X86_64' could in principle be 54# ported to 32-bit as well. ) 55# 56config X86 57 def_bool y 58 # 59 # Note: keep this list sorted alphabetically 60 # 61 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 62 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 63 select ARCH_32BIT_OFF_T if X86_32 64 select ARCH_CLOCKSOURCE_INIT 65 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE 66 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION 67 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 68 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG 69 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) 70 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE 71 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 72 select ARCH_HAS_CACHE_LINE_SIZE 73 select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION 74 select ARCH_HAS_CPU_FINALIZE_INIT 75 select ARCH_HAS_CURRENT_STACK_POINTER 76 select ARCH_HAS_DEBUG_VIRTUAL 77 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE 78 select ARCH_HAS_DEVMEM_IS_ALLOWED 79 select ARCH_HAS_EARLY_DEBUG if KGDB 80 select ARCH_HAS_ELF_RANDOMIZE 81 select ARCH_HAS_FAST_MULTIPLIER 82 select ARCH_HAS_FORTIFY_SOURCE 83 select ARCH_HAS_GCOV_PROFILE_ALL 84 select ARCH_HAS_KCOV if X86_64 85 select ARCH_HAS_MEM_ENCRYPT 86 select ARCH_HAS_MEMBARRIER_SYNC_CORE 87 select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS 88 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 89 select ARCH_HAS_PMEM_API if X86_64 90 select ARCH_HAS_PTE_DEVMAP if X86_64 91 select ARCH_HAS_PTE_SPECIAL 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_MIGHT_HAVE_ACPI_PDC if ACPI 106 select ARCH_MIGHT_HAVE_PC_PARPORT 107 select ARCH_MIGHT_HAVE_PC_SERIO 108 select ARCH_STACKWALK 109 select ARCH_SUPPORTS_ACPI 110 select ARCH_SUPPORTS_ATOMIC_RMW 111 select ARCH_SUPPORTS_DEBUG_PAGEALLOC 112 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 113 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 114 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 115 select ARCH_SUPPORTS_CFI_CLANG if X86_64 116 select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG 117 select ARCH_SUPPORTS_LTO_CLANG 118 select ARCH_SUPPORTS_LTO_CLANG_THIN 119 select ARCH_USE_BUILTIN_BSWAP 120 select ARCH_USE_MEMTEST 121 select ARCH_USE_QUEUED_RWLOCKS 122 select ARCH_USE_QUEUED_SPINLOCKS 123 select ARCH_USE_SYM_ANNOTATIONS 124 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 125 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 126 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 127 select ARCH_WANTS_NO_INSTR 128 select ARCH_WANT_GENERAL_HUGETLB 129 select ARCH_WANT_HUGE_PMD_SHARE 130 select ARCH_WANT_LD_ORPHAN_WARN 131 select ARCH_WANT_OPTIMIZE_VMEMMAP if X86_64 132 select ARCH_WANTS_THP_SWAP if X86_64 133 select ARCH_HAS_PARANOID_L1D_FLUSH 134 select BUILDTIME_TABLE_SORT 135 select CLKEVT_I8253 136 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 137 select CLOCKSOURCE_WATCHDOG 138 # Word-size accesses may read uninitialized data past the trailing \0 139 # in strings and cause false KMSAN reports. 140 select DCACHE_WORD_ACCESS if !KMSAN 141 select DYNAMIC_SIGFRAME 142 select EDAC_ATOMIC_SCRUB 143 select EDAC_SUPPORT 144 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 145 select GENERIC_CLOCKEVENTS_MIN_ADJUST 146 select GENERIC_CMOS_UPDATE 147 select GENERIC_CPU_AUTOPROBE 148 select GENERIC_CPU_VULNERABILITIES 149 select GENERIC_EARLY_IOREMAP 150 select GENERIC_ENTRY 151 select GENERIC_IOMAP 152 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 153 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 154 select GENERIC_IRQ_MIGRATION if SMP 155 select GENERIC_IRQ_PROBE 156 select GENERIC_IRQ_RESERVATION_MODE 157 select GENERIC_IRQ_SHOW 158 select GENERIC_PENDING_IRQ if SMP 159 select GENERIC_PTDUMP 160 select GENERIC_SMP_IDLE_THREAD 161 select GENERIC_TIME_VSYSCALL 162 select GENERIC_GETTIMEOFDAY 163 select GENERIC_VDSO_TIME_NS 164 select GUP_GET_PXX_LOW_HIGH if X86_PAE 165 select HARDIRQS_SW_RESEND 166 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 167 select HAS_IOPORT 168 select HAVE_ACPI_APEI if ACPI 169 select HAVE_ACPI_APEI_NMI if ACPI 170 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 171 select HAVE_ARCH_AUDITSYSCALL 172 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 173 select HAVE_ARCH_HUGE_VMALLOC if X86_64 174 select HAVE_ARCH_JUMP_LABEL 175 select HAVE_ARCH_JUMP_LABEL_RELATIVE 176 select HAVE_ARCH_KASAN if X86_64 177 select HAVE_ARCH_KASAN_VMALLOC if X86_64 178 select HAVE_ARCH_KFENCE 179 select HAVE_ARCH_KMSAN if X86_64 180 select HAVE_ARCH_KGDB 181 select HAVE_ARCH_MMAP_RND_BITS if MMU 182 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 183 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 184 select HAVE_ARCH_PREL32_RELOCATIONS 185 select HAVE_ARCH_SECCOMP_FILTER 186 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 187 select HAVE_ARCH_STACKLEAK 188 select HAVE_ARCH_TRACEHOOK 189 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 190 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 191 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 192 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 193 select HAVE_ARCH_VMAP_STACK if X86_64 194 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 195 select HAVE_ARCH_WITHIN_STACK_FRAMES 196 select HAVE_ASM_MODVERSIONS 197 select HAVE_CMPXCHG_DOUBLE 198 select HAVE_CMPXCHG_LOCAL 199 select HAVE_CONTEXT_TRACKING_USER if X86_64 200 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 201 select HAVE_C_RECORDMCOUNT 202 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 203 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 204 select HAVE_BUILDTIME_MCOUNT_SORT 205 select HAVE_DEBUG_KMEMLEAK 206 select HAVE_DMA_CONTIGUOUS 207 select HAVE_DYNAMIC_FTRACE 208 select HAVE_DYNAMIC_FTRACE_WITH_REGS 209 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 210 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 211 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 212 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 213 select HAVE_EBPF_JIT 214 select HAVE_EFFICIENT_UNALIGNED_ACCESS 215 select HAVE_EISA 216 select HAVE_EXIT_THREAD 217 select HAVE_FAST_GUP 218 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 219 select HAVE_FTRACE_MCOUNT_RECORD 220 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 221 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 222 select HAVE_FUNCTION_TRACER 223 select HAVE_GCC_PLUGINS 224 select HAVE_HW_BREAKPOINT 225 select HAVE_IOREMAP_PROT 226 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 227 select HAVE_IRQ_TIME_ACCOUNTING 228 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 229 select HAVE_KERNEL_BZIP2 230 select HAVE_KERNEL_GZIP 231 select HAVE_KERNEL_LZ4 232 select HAVE_KERNEL_LZMA 233 select HAVE_KERNEL_LZO 234 select HAVE_KERNEL_XZ 235 select HAVE_KERNEL_ZSTD 236 select HAVE_KPROBES 237 select HAVE_KPROBES_ON_FTRACE 238 select HAVE_FUNCTION_ERROR_INJECTION 239 select HAVE_KRETPROBES 240 select HAVE_RETHOOK 241 select HAVE_KVM 242 select HAVE_LIVEPATCH if X86_64 243 select HAVE_MIXED_BREAKPOINTS_REGS 244 select HAVE_MOD_ARCH_SPECIFIC 245 select HAVE_MOVE_PMD 246 select HAVE_MOVE_PUD 247 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 248 select HAVE_NMI 249 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 250 select HAVE_OBJTOOL if X86_64 251 select HAVE_OPTPROBES 252 select HAVE_PCSPKR_PLATFORM 253 select HAVE_PERF_EVENTS 254 select HAVE_PERF_EVENTS_NMI 255 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 256 select HAVE_PCI 257 select HAVE_PERF_REGS 258 select HAVE_PERF_USER_STACK_DUMP 259 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 260 select MMU_GATHER_MERGE_VMAS 261 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 262 select HAVE_REGS_AND_STACK_ACCESS_API 263 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 264 select HAVE_FUNCTION_ARG_ACCESS_API 265 select HAVE_SETUP_PER_CPU_AREA 266 select HAVE_SOFTIRQ_ON_OWN_STACK 267 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 268 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 269 select HAVE_STATIC_CALL 270 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 271 select HAVE_PREEMPT_DYNAMIC_CALL 272 select HAVE_RSEQ 273 select HAVE_RUST if X86_64 274 select HAVE_SYSCALL_TRACEPOINTS 275 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 276 select HAVE_UNSTABLE_SCHED_CLOCK 277 select HAVE_USER_RETURN_NOTIFIER 278 select HAVE_GENERIC_VDSO 279 select HOTPLUG_PARALLEL if SMP && X86_64 280 select HOTPLUG_SMT if SMP 281 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 282 select IRQ_FORCED_THREADING 283 select LOCK_MM_AND_FIND_VMA 284 select NEED_PER_CPU_EMBED_FIRST_CHUNK 285 select NEED_PER_CPU_PAGE_FIRST_CHUNK 286 select NEED_SG_DMA_LENGTH 287 select PCI_DOMAINS if PCI 288 select PCI_LOCKLESS_CONFIG if PCI 289 select PERF_EVENTS 290 select RTC_LIB 291 select RTC_MC146818_LIB 292 select SPARSE_IRQ 293 select SYSCTL_EXCEPTION_TRACE 294 select THREAD_INFO_IN_TASK 295 select TRACE_IRQFLAGS_SUPPORT 296 select TRACE_IRQFLAGS_NMI_SUPPORT 297 select USER_STACKTRACE_SUPPORT 298 select HAVE_ARCH_KCSAN if X86_64 299 select PROC_PID_ARCH_STATUS if PROC_FS 300 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 301 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 302 select FUNCTION_ALIGNMENT_4B 303 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 304 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 305 306config INSTRUCTION_DECODER 307 def_bool y 308 depends on KPROBES || PERF_EVENTS || UPROBES 309 310config OUTPUT_FORMAT 311 string 312 default "elf32-i386" if X86_32 313 default "elf64-x86-64" if X86_64 314 315config LOCKDEP_SUPPORT 316 def_bool y 317 318config STACKTRACE_SUPPORT 319 def_bool y 320 321config MMU 322 def_bool y 323 324config ARCH_MMAP_RND_BITS_MIN 325 default 28 if 64BIT 326 default 8 327 328config ARCH_MMAP_RND_BITS_MAX 329 default 32 if 64BIT 330 default 16 331 332config ARCH_MMAP_RND_COMPAT_BITS_MIN 333 default 8 334 335config ARCH_MMAP_RND_COMPAT_BITS_MAX 336 default 16 337 338config SBUS 339 bool 340 341config GENERIC_ISA_DMA 342 def_bool y 343 depends on ISA_DMA_API 344 345config GENERIC_CSUM 346 bool 347 default y if KMSAN || KASAN 348 349config GENERIC_BUG 350 def_bool y 351 depends on BUG 352 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 353 354config GENERIC_BUG_RELATIVE_POINTERS 355 bool 356 357config ARCH_MAY_HAVE_PC_FDC 358 def_bool y 359 depends on ISA_DMA_API 360 361config GENERIC_CALIBRATE_DELAY 362 def_bool y 363 364config ARCH_HAS_CPU_RELAX 365 def_bool y 366 367config ARCH_HIBERNATION_POSSIBLE 368 def_bool y 369 370config ARCH_SUSPEND_POSSIBLE 371 def_bool y 372 373config AUDIT_ARCH 374 def_bool y if X86_64 375 376config KASAN_SHADOW_OFFSET 377 hex 378 depends on KASAN 379 default 0xdffffc0000000000 380 381config HAVE_INTEL_TXT 382 def_bool y 383 depends on INTEL_IOMMU && ACPI 384 385config X86_32_SMP 386 def_bool y 387 depends on X86_32 && SMP 388 389config X86_64_SMP 390 def_bool y 391 depends on X86_64 && SMP 392 393config ARCH_SUPPORTS_UPROBES 394 def_bool y 395 396config FIX_EARLYCON_MEM 397 def_bool y 398 399config DYNAMIC_PHYSICAL_MASK 400 bool 401 402config PGTABLE_LEVELS 403 int 404 default 5 if X86_5LEVEL 405 default 4 if X86_64 406 default 3 if X86_PAE 407 default 2 408 409config CC_HAS_SANE_STACKPROTECTOR 410 bool 411 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 412 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 413 help 414 We have to make sure stack protector is unconditionally disabled if 415 the compiler produces broken code or if it does not let us control 416 the segment on 32-bit kernels. 417 418menu "Processor type and features" 419 420config SMP 421 bool "Symmetric multi-processing support" 422 help 423 This enables support for systems with more than one CPU. If you have 424 a system with only one CPU, say N. If you have a system with more 425 than one CPU, say Y. 426 427 If you say N here, the kernel will run on uni- and multiprocessor 428 machines, but will use only one CPU of a multiprocessor machine. If 429 you say Y here, the kernel will run on many, but not all, 430 uniprocessor machines. On a uniprocessor machine, the kernel 431 will run faster if you say N here. 432 433 Note that if you say Y here and choose architecture "586" or 434 "Pentium" under "Processor family", the kernel will not work on 486 435 architectures. Similarly, multiprocessor kernels for the "PPro" 436 architecture may not work on all Pentium based boards. 437 438 People using multiprocessor machines who say Y here should also say 439 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 440 Management" code will be disabled if you say Y here. 441 442 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 443 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 444 <http://www.tldp.org/docs.html#howto>. 445 446 If you don't know what to do here, say N. 447 448config X86_X2APIC 449 bool "Support x2apic" 450 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 451 help 452 This enables x2apic support on CPUs that have this feature. 453 454 This allows 32-bit apic IDs (so it can support very large systems), 455 and accesses the local apic via MSRs not via mmio. 456 457 Some Intel systems circa 2022 and later are locked into x2APIC mode 458 and can not fall back to the legacy APIC modes if SGX or TDX are 459 enabled in the BIOS. They will boot with very reduced functionality 460 without enabling this option. 461 462 If you don't know what to do here, say N. 463 464config X86_MPPARSE 465 bool "Enable MPS table" if ACPI 466 default y 467 depends on X86_LOCAL_APIC 468 help 469 For old smp systems that do not have proper acpi support. Newer systems 470 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 471 472config GOLDFISH 473 def_bool y 474 depends on X86_GOLDFISH 475 476config X86_CPU_RESCTRL 477 bool "x86 CPU resource control support" 478 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 479 select KERNFS 480 select PROC_CPU_RESCTRL if PROC_FS 481 help 482 Enable x86 CPU resource control support. 483 484 Provide support for the allocation and monitoring of system resources 485 usage by the CPU. 486 487 Intel calls this Intel Resource Director Technology 488 (Intel(R) RDT). More information about RDT can be found in the 489 Intel x86 Architecture Software Developer Manual. 490 491 AMD calls this AMD Platform Quality of Service (AMD QoS). 492 More information about AMD QoS can be found in the AMD64 Technology 493 Platform Quality of Service Extensions manual. 494 495 Say N if unsure. 496 497if X86_32 498config X86_BIGSMP 499 bool "Support for big SMP systems with more than 8 CPUs" 500 depends on SMP 501 help 502 This option is needed for the systems that have more than 8 CPUs. 503 504config X86_EXTENDED_PLATFORM 505 bool "Support for extended (non-PC) x86 platforms" 506 default y 507 help 508 If you disable this option then the kernel will only support 509 standard PC platforms. (which covers the vast majority of 510 systems out there.) 511 512 If you enable this option then you'll be able to select support 513 for the following (non-PC) 32 bit x86 platforms: 514 Goldfish (Android emulator) 515 AMD Elan 516 RDC R-321x SoC 517 SGI 320/540 (Visual Workstation) 518 STA2X11-based (e.g. Northville) 519 Moorestown MID devices 520 521 If you have one of these systems, or if you want to build a 522 generic distribution kernel, say Y here - otherwise say N. 523endif # X86_32 524 525if X86_64 526config X86_EXTENDED_PLATFORM 527 bool "Support for extended (non-PC) x86 platforms" 528 default y 529 help 530 If you disable this option then the kernel will only support 531 standard PC platforms. (which covers the vast majority of 532 systems out there.) 533 534 If you enable this option then you'll be able to select support 535 for the following (non-PC) 64 bit x86 platforms: 536 Numascale NumaChip 537 ScaleMP vSMP 538 SGI Ultraviolet 539 540 If you have one of these systems, or if you want to build a 541 generic distribution kernel, say Y here - otherwise say N. 542endif # X86_64 543# This is an alphabetically sorted list of 64 bit extended platforms 544# Please maintain the alphabetic order if and when there are additions 545config X86_NUMACHIP 546 bool "Numascale NumaChip" 547 depends on X86_64 548 depends on X86_EXTENDED_PLATFORM 549 depends on NUMA 550 depends on SMP 551 depends on X86_X2APIC 552 depends on PCI_MMCONFIG 553 help 554 Adds support for Numascale NumaChip large-SMP systems. Needed to 555 enable more than ~168 cores. 556 If you don't have one of these, you should say N here. 557 558config X86_VSMP 559 bool "ScaleMP vSMP" 560 select HYPERVISOR_GUEST 561 select PARAVIRT 562 depends on X86_64 && PCI 563 depends on X86_EXTENDED_PLATFORM 564 depends on SMP 565 help 566 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 567 supposed to run on these EM64T-based machines. Only choose this option 568 if you have one of these machines. 569 570config X86_UV 571 bool "SGI Ultraviolet" 572 depends on X86_64 573 depends on X86_EXTENDED_PLATFORM 574 depends on NUMA 575 depends on EFI 576 depends on KEXEC_CORE 577 depends on X86_X2APIC 578 depends on PCI 579 help 580 This option is needed in order to support SGI Ultraviolet systems. 581 If you don't have one of these, you should say N here. 582 583# Following is an alphabetically sorted list of 32 bit extended platforms 584# Please maintain the alphabetic order if and when there are additions 585 586config X86_GOLDFISH 587 bool "Goldfish (Virtual Platform)" 588 depends on X86_EXTENDED_PLATFORM 589 help 590 Enable support for the Goldfish virtual platform used primarily 591 for Android development. Unless you are building for the Android 592 Goldfish emulator say N here. 593 594config X86_INTEL_CE 595 bool "CE4100 TV platform" 596 depends on PCI 597 depends on PCI_GODIRECT 598 depends on X86_IO_APIC 599 depends on X86_32 600 depends on X86_EXTENDED_PLATFORM 601 select X86_REBOOTFIXUPS 602 select OF 603 select OF_EARLY_FLATTREE 604 help 605 Select for the Intel CE media processor (CE4100) SOC. 606 This option compiles in support for the CE4100 SOC for settop 607 boxes and media devices. 608 609config X86_INTEL_MID 610 bool "Intel MID platform support" 611 depends on X86_EXTENDED_PLATFORM 612 depends on X86_PLATFORM_DEVICES 613 depends on PCI 614 depends on X86_64 || (PCI_GOANY && X86_32) 615 depends on X86_IO_APIC 616 select I2C 617 select DW_APB_TIMER 618 select INTEL_SCU_PCI 619 help 620 Select to build a kernel capable of supporting Intel MID (Mobile 621 Internet Device) platform systems which do not have the PCI legacy 622 interfaces. If you are building for a PC class system say N here. 623 624 Intel MID platforms are based on an Intel processor and chipset which 625 consume less power than most of the x86 derivatives. 626 627config X86_INTEL_QUARK 628 bool "Intel Quark platform support" 629 depends on X86_32 630 depends on X86_EXTENDED_PLATFORM 631 depends on X86_PLATFORM_DEVICES 632 depends on X86_TSC 633 depends on PCI 634 depends on PCI_GOANY 635 depends on X86_IO_APIC 636 select IOSF_MBI 637 select INTEL_IMR 638 select COMMON_CLK 639 help 640 Select to include support for Quark X1000 SoC. 641 Say Y here if you have a Quark based system such as the Arduino 642 compatible Intel Galileo. 643 644config X86_INTEL_LPSS 645 bool "Intel Low Power Subsystem Support" 646 depends on X86 && ACPI && PCI 647 select COMMON_CLK 648 select PINCTRL 649 select IOSF_MBI 650 help 651 Select to build support for Intel Low Power Subsystem such as 652 found on Intel Lynxpoint PCH. Selecting this option enables 653 things like clock tree (common clock framework) and pincontrol 654 which are needed by the LPSS peripheral drivers. 655 656config X86_AMD_PLATFORM_DEVICE 657 bool "AMD ACPI2Platform devices support" 658 depends on ACPI 659 select COMMON_CLK 660 select PINCTRL 661 help 662 Select to interpret AMD specific ACPI device to platform device 663 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 664 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 665 implemented under PINCTRL subsystem. 666 667config IOSF_MBI 668 tristate "Intel SoC IOSF Sideband support for SoC platforms" 669 depends on PCI 670 help 671 This option enables sideband register access support for Intel SoC 672 platforms. On these platforms the IOSF sideband is used in lieu of 673 MSR's for some register accesses, mostly but not limited to thermal 674 and power. Drivers may query the availability of this device to 675 determine if they need the sideband in order to work on these 676 platforms. The sideband is available on the following SoC products. 677 This list is not meant to be exclusive. 678 - BayTrail 679 - Braswell 680 - Quark 681 682 You should say Y if you are running a kernel on one of these SoC's. 683 684config IOSF_MBI_DEBUG 685 bool "Enable IOSF sideband access through debugfs" 686 depends on IOSF_MBI && DEBUG_FS 687 help 688 Select this option to expose the IOSF sideband access registers (MCR, 689 MDR, MCRX) through debugfs to write and read register information from 690 different units on the SoC. This is most useful for obtaining device 691 state information for debug and analysis. As this is a general access 692 mechanism, users of this option would have specific knowledge of the 693 device they want to access. 694 695 If you don't require the option or are in doubt, say N. 696 697config X86_RDC321X 698 bool "RDC R-321x SoC" 699 depends on X86_32 700 depends on X86_EXTENDED_PLATFORM 701 select M486 702 select X86_REBOOTFIXUPS 703 help 704 This option is needed for RDC R-321x system-on-chip, also known 705 as R-8610-(G). 706 If you don't have one of these chips, you should say N here. 707 708config X86_32_NON_STANDARD 709 bool "Support non-standard 32-bit SMP architectures" 710 depends on X86_32 && SMP 711 depends on X86_EXTENDED_PLATFORM 712 help 713 This option compiles in the bigsmp and STA2X11 default 714 subarchitectures. It is intended for a generic binary 715 kernel. If you select them all, kernel will probe it one by 716 one and will fallback to default. 717 718# Alphabetically sorted list of Non standard 32 bit platforms 719 720config X86_SUPPORTS_MEMORY_FAILURE 721 def_bool y 722 # MCE code calls memory_failure(): 723 depends on X86_MCE 724 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 725 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 726 depends on X86_64 || !SPARSEMEM 727 select ARCH_SUPPORTS_MEMORY_FAILURE 728 729config STA2X11 730 bool "STA2X11 Companion Chip Support" 731 depends on X86_32_NON_STANDARD && PCI 732 select SWIOTLB 733 select MFD_STA2X11 734 select GPIOLIB 735 help 736 This adds support for boards based on the STA2X11 IO-Hub, 737 a.k.a. "ConneXt". The chip is used in place of the standard 738 PC chipset, so all "standard" peripherals are missing. If this 739 option is selected the kernel will still be able to boot on 740 standard PC machines. 741 742config X86_32_IRIS 743 tristate "Eurobraille/Iris poweroff module" 744 depends on X86_32 745 help 746 The Iris machines from EuroBraille do not have APM or ACPI support 747 to shut themselves down properly. A special I/O sequence is 748 needed to do so, which is what this module does at 749 kernel shutdown. 750 751 This is only for Iris machines from EuroBraille. 752 753 If unused, say N. 754 755config SCHED_OMIT_FRAME_POINTER 756 def_bool y 757 prompt "Single-depth WCHAN output" 758 depends on X86 759 help 760 Calculate simpler /proc/<PID>/wchan values. If this option 761 is disabled then wchan values will recurse back to the 762 caller function. This provides more accurate wchan values, 763 at the expense of slightly more scheduling overhead. 764 765 If in doubt, say "Y". 766 767menuconfig HYPERVISOR_GUEST 768 bool "Linux guest support" 769 help 770 Say Y here to enable options for running Linux under various hyper- 771 visors. This option enables basic hypervisor detection and platform 772 setup. 773 774 If you say N, all options in this submenu will be skipped and 775 disabled, and Linux guest support won't be built in. 776 777if HYPERVISOR_GUEST 778 779config PARAVIRT 780 bool "Enable paravirtualization code" 781 depends on HAVE_STATIC_CALL 782 help 783 This changes the kernel so it can modify itself when it is run 784 under a hypervisor, potentially improving performance significantly 785 over full virtualization. However, when run without a hypervisor 786 the kernel is theoretically slower and slightly larger. 787 788config PARAVIRT_XXL 789 bool 790 791config PARAVIRT_DEBUG 792 bool "paravirt-ops debugging" 793 depends on PARAVIRT && DEBUG_KERNEL 794 help 795 Enable to debug paravirt_ops internals. Specifically, BUG if 796 a paravirt_op is missing when it is called. 797 798config PARAVIRT_SPINLOCKS 799 bool "Paravirtualization layer for spinlocks" 800 depends on PARAVIRT && SMP 801 help 802 Paravirtualized spinlocks allow a pvops backend to replace the 803 spinlock implementation with something virtualization-friendly 804 (for example, block the virtual CPU rather than spinning). 805 806 It has a minimal impact on native kernels and gives a nice performance 807 benefit on paravirtualized KVM / Xen kernels. 808 809 If you are unsure how to answer this question, answer Y. 810 811config X86_HV_CALLBACK_VECTOR 812 def_bool n 813 814source "arch/x86/xen/Kconfig" 815 816config KVM_GUEST 817 bool "KVM Guest support (including kvmclock)" 818 depends on PARAVIRT 819 select PARAVIRT_CLOCK 820 select ARCH_CPUIDLE_HALTPOLL 821 select X86_HV_CALLBACK_VECTOR 822 default y 823 help 824 This option enables various optimizations for running under the KVM 825 hypervisor. It includes a paravirtualized clock, so that instead 826 of relying on a PIT (or probably other) emulation by the 827 underlying device model, the host provides the guest with 828 timing infrastructure such as time of day, and system time 829 830config ARCH_CPUIDLE_HALTPOLL 831 def_bool n 832 prompt "Disable host haltpoll when loading haltpoll driver" 833 help 834 If virtualized under KVM, disable host haltpoll. 835 836config PVH 837 bool "Support for running PVH guests" 838 help 839 This option enables the PVH entry point for guest virtual machines 840 as specified in the x86/HVM direct boot ABI. 841 842config PARAVIRT_TIME_ACCOUNTING 843 bool "Paravirtual steal time accounting" 844 depends on PARAVIRT 845 help 846 Select this option to enable fine granularity task steal time 847 accounting. Time spent executing other tasks in parallel with 848 the current vCPU is discounted from the vCPU power. To account for 849 that, there can be a small performance impact. 850 851 If in doubt, say N here. 852 853config PARAVIRT_CLOCK 854 bool 855 856config JAILHOUSE_GUEST 857 bool "Jailhouse non-root cell support" 858 depends on X86_64 && PCI 859 select X86_PM_TIMER 860 help 861 This option allows to run Linux as guest in a Jailhouse non-root 862 cell. You can leave this option disabled if you only want to start 863 Jailhouse and run Linux afterwards in the root cell. 864 865config ACRN_GUEST 866 bool "ACRN Guest support" 867 depends on X86_64 868 select X86_HV_CALLBACK_VECTOR 869 help 870 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 871 a flexible, lightweight reference open-source hypervisor, built with 872 real-time and safety-criticality in mind. It is built for embedded 873 IOT with small footprint and real-time features. More details can be 874 found in https://projectacrn.org/. 875 876config INTEL_TDX_GUEST 877 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 878 depends on X86_64 && CPU_SUP_INTEL 879 depends on X86_X2APIC 880 depends on EFI_STUB 881 select ARCH_HAS_CC_PLATFORM 882 select X86_MEM_ENCRYPT 883 select X86_MCE 884 select UNACCEPTED_MEMORY 885 help 886 Support running as a guest under Intel TDX. Without this support, 887 the guest kernel can not boot or run under TDX. 888 TDX includes memory encryption and integrity capabilities 889 which protect the confidentiality and integrity of guest 890 memory contents and CPU state. TDX guests are protected from 891 some attacks from the VMM. 892 893endif # HYPERVISOR_GUEST 894 895source "arch/x86/Kconfig.cpu" 896 897config HPET_TIMER 898 def_bool X86_64 899 prompt "HPET Timer Support" if X86_32 900 help 901 Use the IA-PC HPET (High Precision Event Timer) to manage 902 time in preference to the PIT and RTC, if a HPET is 903 present. 904 HPET is the next generation timer replacing legacy 8254s. 905 The HPET provides a stable time base on SMP 906 systems, unlike the TSC, but it is more expensive to access, 907 as it is off-chip. The interface used is documented 908 in the HPET spec, revision 1. 909 910 You can safely choose Y here. However, HPET will only be 911 activated if the platform and the BIOS support this feature. 912 Otherwise the 8254 will be used for timing services. 913 914 Choose N to continue using the legacy 8254 timer. 915 916config HPET_EMULATE_RTC 917 def_bool y 918 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 919 920# Mark as expert because too many people got it wrong. 921# The code disables itself when not needed. 922config DMI 923 default y 924 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 925 bool "Enable DMI scanning" if EXPERT 926 help 927 Enabled scanning of DMI to identify machine quirks. Say Y 928 here unless you have verified that your setup is not 929 affected by entries in the DMI blacklist. Required by PNP 930 BIOS code. 931 932config GART_IOMMU 933 bool "Old AMD GART IOMMU support" 934 select DMA_OPS 935 select IOMMU_HELPER 936 select SWIOTLB 937 depends on X86_64 && PCI && AMD_NB 938 help 939 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 940 GART based hardware IOMMUs. 941 942 The GART supports full DMA access for devices with 32-bit access 943 limitations, on systems with more than 3 GB. This is usually needed 944 for USB, sound, many IDE/SATA chipsets and some other devices. 945 946 Newer systems typically have a modern AMD IOMMU, supported via 947 the CONFIG_AMD_IOMMU=y config option. 948 949 In normal configurations this driver is only active when needed: 950 there's more than 3 GB of memory and the system contains a 951 32-bit limited device. 952 953 If unsure, say Y. 954 955config BOOT_VESA_SUPPORT 956 bool 957 help 958 If true, at least one selected framebuffer driver can take advantage 959 of VESA video modes set at an early boot stage via the vga= parameter. 960 961config MAXSMP 962 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 963 depends on X86_64 && SMP && DEBUG_KERNEL 964 select CPUMASK_OFFSTACK 965 help 966 Enable maximum number of CPUS and NUMA Nodes for this architecture. 967 If unsure, say N. 968 969# 970# The maximum number of CPUs supported: 971# 972# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 973# and which can be configured interactively in the 974# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 975# 976# The ranges are different on 32-bit and 64-bit kernels, depending on 977# hardware capabilities and scalability features of the kernel. 978# 979# ( If MAXSMP is enabled we just use the highest possible value and disable 980# interactive configuration. ) 981# 982 983config NR_CPUS_RANGE_BEGIN 984 int 985 default NR_CPUS_RANGE_END if MAXSMP 986 default 1 if !SMP 987 default 2 988 989config NR_CPUS_RANGE_END 990 int 991 depends on X86_32 992 default 64 if SMP && X86_BIGSMP 993 default 8 if SMP && !X86_BIGSMP 994 default 1 if !SMP 995 996config NR_CPUS_RANGE_END 997 int 998 depends on X86_64 999 default 8192 if SMP && CPUMASK_OFFSTACK 1000 default 512 if SMP && !CPUMASK_OFFSTACK 1001 default 1 if !SMP 1002 1003config NR_CPUS_DEFAULT 1004 int 1005 depends on X86_32 1006 default 32 if X86_BIGSMP 1007 default 8 if SMP 1008 default 1 if !SMP 1009 1010config NR_CPUS_DEFAULT 1011 int 1012 depends on X86_64 1013 default 8192 if MAXSMP 1014 default 64 if SMP 1015 default 1 if !SMP 1016 1017config NR_CPUS 1018 int "Maximum number of CPUs" if SMP && !MAXSMP 1019 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1020 default NR_CPUS_DEFAULT 1021 help 1022 This allows you to specify the maximum number of CPUs which this 1023 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1024 supported value is 8192, otherwise the maximum value is 512. The 1025 minimum value which makes sense is 2. 1026 1027 This is purely to save memory: each supported CPU adds about 8KB 1028 to the kernel image. 1029 1030config SCHED_CLUSTER 1031 bool "Cluster scheduler support" 1032 depends on SMP 1033 default y 1034 help 1035 Cluster scheduler support improves the CPU scheduler's decision 1036 making when dealing with machines that have clusters of CPUs. 1037 Cluster usually means a couple of CPUs which are placed closely 1038 by sharing mid-level caches, last-level cache tags or internal 1039 busses. 1040 1041config SCHED_SMT 1042 def_bool y if SMP 1043 1044config SCHED_MC 1045 def_bool y 1046 prompt "Multi-core scheduler support" 1047 depends on SMP 1048 help 1049 Multi-core scheduler support improves the CPU scheduler's decision 1050 making when dealing with multi-core CPU chips at a cost of slightly 1051 increased overhead in some places. If unsure say N here. 1052 1053config SCHED_MC_PRIO 1054 bool "CPU core priorities scheduler support" 1055 depends on SCHED_MC && CPU_SUP_INTEL 1056 select X86_INTEL_PSTATE 1057 select CPU_FREQ 1058 default y 1059 help 1060 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1061 core ordering determined at manufacturing time, which allows 1062 certain cores to reach higher turbo frequencies (when running 1063 single threaded workloads) than others. 1064 1065 Enabling this kernel feature teaches the scheduler about 1066 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1067 scheduler's CPU selection logic accordingly, so that higher 1068 overall system performance can be achieved. 1069 1070 This feature will have no effect on CPUs without this feature. 1071 1072 If unsure say Y here. 1073 1074config UP_LATE_INIT 1075 def_bool y 1076 depends on !SMP && X86_LOCAL_APIC 1077 1078config X86_UP_APIC 1079 bool "Local APIC support on uniprocessors" if !PCI_MSI 1080 default PCI_MSI 1081 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1082 help 1083 A local APIC (Advanced Programmable Interrupt Controller) is an 1084 integrated interrupt controller in the CPU. If you have a single-CPU 1085 system which has a processor with a local APIC, you can say Y here to 1086 enable and use it. If you say Y here even though your machine doesn't 1087 have a local APIC, then the kernel will still run with no slowdown at 1088 all. The local APIC supports CPU-generated self-interrupts (timer, 1089 performance counters), and the NMI watchdog which detects hard 1090 lockups. 1091 1092config X86_UP_IOAPIC 1093 bool "IO-APIC support on uniprocessors" 1094 depends on X86_UP_APIC 1095 help 1096 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1097 SMP-capable replacement for PC-style interrupt controllers. Most 1098 SMP systems and many recent uniprocessor systems have one. 1099 1100 If you have a single-CPU system with an IO-APIC, you can say Y here 1101 to use it. If you say Y here even though your machine doesn't have 1102 an IO-APIC, then the kernel will still run with no slowdown at all. 1103 1104config X86_LOCAL_APIC 1105 def_bool y 1106 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1107 select IRQ_DOMAIN_HIERARCHY 1108 1109config X86_IO_APIC 1110 def_bool y 1111 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1112 1113config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1114 bool "Reroute for broken boot IRQs" 1115 depends on X86_IO_APIC 1116 help 1117 This option enables a workaround that fixes a source of 1118 spurious interrupts. This is recommended when threaded 1119 interrupt handling is used on systems where the generation of 1120 superfluous "boot interrupts" cannot be disabled. 1121 1122 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1123 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1124 kernel does during interrupt handling). On chipsets where this 1125 boot IRQ generation cannot be disabled, this workaround keeps 1126 the original IRQ line masked so that only the equivalent "boot 1127 IRQ" is delivered to the CPUs. The workaround also tells the 1128 kernel to set up the IRQ handler on the boot IRQ line. In this 1129 way only one interrupt is delivered to the kernel. Otherwise 1130 the spurious second interrupt may cause the kernel to bring 1131 down (vital) interrupt lines. 1132 1133 Only affects "broken" chipsets. Interrupt sharing may be 1134 increased on these systems. 1135 1136config X86_MCE 1137 bool "Machine Check / overheating reporting" 1138 select GENERIC_ALLOCATOR 1139 default y 1140 help 1141 Machine Check support allows the processor to notify the 1142 kernel if it detects a problem (e.g. overheating, data corruption). 1143 The action the kernel takes depends on the severity of the problem, 1144 ranging from warning messages to halting the machine. 1145 1146config X86_MCELOG_LEGACY 1147 bool "Support for deprecated /dev/mcelog character device" 1148 depends on X86_MCE 1149 help 1150 Enable support for /dev/mcelog which is needed by the old mcelog 1151 userspace logging daemon. Consider switching to the new generation 1152 rasdaemon solution. 1153 1154config X86_MCE_INTEL 1155 def_bool y 1156 prompt "Intel MCE features" 1157 depends on X86_MCE && X86_LOCAL_APIC 1158 help 1159 Additional support for intel specific MCE features such as 1160 the thermal monitor. 1161 1162config X86_MCE_AMD 1163 def_bool y 1164 prompt "AMD MCE features" 1165 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1166 help 1167 Additional support for AMD specific MCE features such as 1168 the DRAM Error Threshold. 1169 1170config X86_ANCIENT_MCE 1171 bool "Support for old Pentium 5 / WinChip machine checks" 1172 depends on X86_32 && X86_MCE 1173 help 1174 Include support for machine check handling on old Pentium 5 or WinChip 1175 systems. These typically need to be enabled explicitly on the command 1176 line. 1177 1178config X86_MCE_THRESHOLD 1179 depends on X86_MCE_AMD || X86_MCE_INTEL 1180 def_bool y 1181 1182config X86_MCE_INJECT 1183 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1184 tristate "Machine check injector support" 1185 help 1186 Provide support for injecting machine checks for testing purposes. 1187 If you don't know what a machine check is and you don't do kernel 1188 QA it is safe to say n. 1189 1190source "arch/x86/events/Kconfig" 1191 1192config X86_LEGACY_VM86 1193 bool "Legacy VM86 support" 1194 depends on X86_32 1195 help 1196 This option allows user programs to put the CPU into V8086 1197 mode, which is an 80286-era approximation of 16-bit real mode. 1198 1199 Some very old versions of X and/or vbetool require this option 1200 for user mode setting. Similarly, DOSEMU will use it if 1201 available to accelerate real mode DOS programs. However, any 1202 recent version of DOSEMU, X, or vbetool should be fully 1203 functional even without kernel VM86 support, as they will all 1204 fall back to software emulation. Nevertheless, if you are using 1205 a 16-bit DOS program where 16-bit performance matters, vm86 1206 mode might be faster than emulation and you might want to 1207 enable this option. 1208 1209 Note that any app that works on a 64-bit kernel is unlikely to 1210 need this option, as 64-bit kernels don't, and can't, support 1211 V8086 mode. This option is also unrelated to 16-bit protected 1212 mode and is not needed to run most 16-bit programs under Wine. 1213 1214 Enabling this option increases the complexity of the kernel 1215 and slows down exception handling a tiny bit. 1216 1217 If unsure, say N here. 1218 1219config VM86 1220 bool 1221 default X86_LEGACY_VM86 1222 1223config X86_16BIT 1224 bool "Enable support for 16-bit segments" if EXPERT 1225 default y 1226 depends on MODIFY_LDT_SYSCALL 1227 help 1228 This option is required by programs like Wine to run 16-bit 1229 protected mode legacy code on x86 processors. Disabling 1230 this option saves about 300 bytes on i386, or around 6K text 1231 plus 16K runtime memory on x86-64, 1232 1233config X86_ESPFIX32 1234 def_bool y 1235 depends on X86_16BIT && X86_32 1236 1237config X86_ESPFIX64 1238 def_bool y 1239 depends on X86_16BIT && X86_64 1240 1241config X86_VSYSCALL_EMULATION 1242 bool "Enable vsyscall emulation" if EXPERT 1243 default y 1244 depends on X86_64 1245 help 1246 This enables emulation of the legacy vsyscall page. Disabling 1247 it is roughly equivalent to booting with vsyscall=none, except 1248 that it will also disable the helpful warning if a program 1249 tries to use a vsyscall. With this option set to N, offending 1250 programs will just segfault, citing addresses of the form 1251 0xffffffffff600?00. 1252 1253 This option is required by many programs built before 2013, and 1254 care should be used even with newer programs if set to N. 1255 1256 Disabling this option saves about 7K of kernel size and 1257 possibly 4K of additional runtime pagetable memory. 1258 1259config X86_IOPL_IOPERM 1260 bool "IOPERM and IOPL Emulation" 1261 default y 1262 help 1263 This enables the ioperm() and iopl() syscalls which are necessary 1264 for legacy applications. 1265 1266 Legacy IOPL support is an overbroad mechanism which allows user 1267 space aside of accessing all 65536 I/O ports also to disable 1268 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1269 capabilities and permission from potentially active security 1270 modules. 1271 1272 The emulation restricts the functionality of the syscall to 1273 only allowing the full range I/O port access, but prevents the 1274 ability to disable interrupts from user space which would be 1275 granted if the hardware IOPL mechanism would be used. 1276 1277config TOSHIBA 1278 tristate "Toshiba Laptop support" 1279 depends on X86_32 1280 help 1281 This adds a driver to safely access the System Management Mode of 1282 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1283 not work on models with a Phoenix BIOS. The System Management Mode 1284 is used to set the BIOS and power saving options on Toshiba portables. 1285 1286 For information on utilities to make use of this driver see the 1287 Toshiba Linux utilities web site at: 1288 <http://www.buzzard.org.uk/toshiba/>. 1289 1290 Say Y if you intend to run this kernel on a Toshiba portable. 1291 Say N otherwise. 1292 1293config X86_REBOOTFIXUPS 1294 bool "Enable X86 board specific fixups for reboot" 1295 depends on X86_32 1296 help 1297 This enables chipset and/or board specific fixups to be done 1298 in order to get reboot to work correctly. This is only needed on 1299 some combinations of hardware and BIOS. The symptom, for which 1300 this config is intended, is when reboot ends with a stalled/hung 1301 system. 1302 1303 Currently, the only fixup is for the Geode machines using 1304 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1305 1306 Say Y if you want to enable the fixup. Currently, it's safe to 1307 enable this option even if you don't need it. 1308 Say N otherwise. 1309 1310config MICROCODE 1311 bool "CPU microcode loading support" 1312 default y 1313 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1314 help 1315 If you say Y here, you will be able to update the microcode on 1316 Intel and AMD processors. The Intel support is for the IA32 family, 1317 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1318 AMD support is for families 0x10 and later. You will obviously need 1319 the actual microcode binary data itself which is not shipped with 1320 the Linux kernel. 1321 1322 The preferred method to load microcode from a detached initrd is described 1323 in Documentation/arch/x86/microcode.rst. For that you need to enable 1324 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1325 initrd for microcode blobs. 1326 1327 In addition, you can build the microcode into the kernel. For that you 1328 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1329 config option. 1330 1331config MICROCODE_INTEL 1332 bool "Intel microcode loading support" 1333 depends on CPU_SUP_INTEL && MICROCODE 1334 default MICROCODE 1335 help 1336 This options enables microcode patch loading support for Intel 1337 processors. 1338 1339 For the current Intel microcode data package go to 1340 <https://downloadcenter.intel.com> and search for 1341 'Linux Processor Microcode Data File'. 1342 1343config MICROCODE_AMD 1344 bool "AMD microcode loading support" 1345 depends on CPU_SUP_AMD && MICROCODE 1346 help 1347 If you select this option, microcode patch loading support for AMD 1348 processors will be enabled. 1349 1350config MICROCODE_LATE_LOADING 1351 bool "Late microcode loading (DANGEROUS)" 1352 default n 1353 depends on MICROCODE 1354 help 1355 Loading microcode late, when the system is up and executing instructions 1356 is a tricky business and should be avoided if possible. Just the sequence 1357 of synchronizing all cores and SMT threads is one fragile dance which does 1358 not guarantee that cores might not softlock after the loading. Therefore, 1359 use this at your own risk. Late loading taints the kernel too. 1360 1361config X86_MSR 1362 tristate "/dev/cpu/*/msr - Model-specific register support" 1363 help 1364 This device gives privileged processes access to the x86 1365 Model-Specific Registers (MSRs). It is a character device with 1366 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1367 MSR accesses are directed to a specific CPU on multi-processor 1368 systems. 1369 1370config X86_CPUID 1371 tristate "/dev/cpu/*/cpuid - CPU information support" 1372 help 1373 This device gives processes access to the x86 CPUID instruction to 1374 be executed on a specific processor. It is a character device 1375 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1376 /dev/cpu/31/cpuid. 1377 1378choice 1379 prompt "High Memory Support" 1380 default HIGHMEM4G 1381 depends on X86_32 1382 1383config NOHIGHMEM 1384 bool "off" 1385 help 1386 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1387 However, the address space of 32-bit x86 processors is only 4 1388 Gigabytes large. That means that, if you have a large amount of 1389 physical memory, not all of it can be "permanently mapped" by the 1390 kernel. The physical memory that's not permanently mapped is called 1391 "high memory". 1392 1393 If you are compiling a kernel which will never run on a machine with 1394 more than 1 Gigabyte total physical RAM, answer "off" here (default 1395 choice and suitable for most users). This will result in a "3GB/1GB" 1396 split: 3GB are mapped so that each process sees a 3GB virtual memory 1397 space and the remaining part of the 4GB virtual memory space is used 1398 by the kernel to permanently map as much physical memory as 1399 possible. 1400 1401 If the machine has between 1 and 4 Gigabytes physical RAM, then 1402 answer "4GB" here. 1403 1404 If more than 4 Gigabytes is used then answer "64GB" here. This 1405 selection turns Intel PAE (Physical Address Extension) mode on. 1406 PAE implements 3-level paging on IA32 processors. PAE is fully 1407 supported by Linux, PAE mode is implemented on all recent Intel 1408 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1409 then the kernel will not boot on CPUs that don't support PAE! 1410 1411 The actual amount of total physical memory will either be 1412 auto detected or can be forced by using a kernel command line option 1413 such as "mem=256M". (Try "man bootparam" or see the documentation of 1414 your boot loader (lilo or loadlin) about how to pass options to the 1415 kernel at boot time.) 1416 1417 If unsure, say "off". 1418 1419config HIGHMEM4G 1420 bool "4GB" 1421 help 1422 Select this if you have a 32-bit processor and between 1 and 4 1423 gigabytes of physical RAM. 1424 1425config HIGHMEM64G 1426 bool "64GB" 1427 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1428 select X86_PAE 1429 help 1430 Select this if you have a 32-bit processor and more than 4 1431 gigabytes of physical RAM. 1432 1433endchoice 1434 1435choice 1436 prompt "Memory split" if EXPERT 1437 default VMSPLIT_3G 1438 depends on X86_32 1439 help 1440 Select the desired split between kernel and user memory. 1441 1442 If the address range available to the kernel is less than the 1443 physical memory installed, the remaining memory will be available 1444 as "high memory". Accessing high memory is a little more costly 1445 than low memory, as it needs to be mapped into the kernel first. 1446 Note that increasing the kernel address space limits the range 1447 available to user programs, making the address space there 1448 tighter. Selecting anything other than the default 3G/1G split 1449 will also likely make your kernel incompatible with binary-only 1450 kernel modules. 1451 1452 If you are not absolutely sure what you are doing, leave this 1453 option alone! 1454 1455 config VMSPLIT_3G 1456 bool "3G/1G user/kernel split" 1457 config VMSPLIT_3G_OPT 1458 depends on !X86_PAE 1459 bool "3G/1G user/kernel split (for full 1G low memory)" 1460 config VMSPLIT_2G 1461 bool "2G/2G user/kernel split" 1462 config VMSPLIT_2G_OPT 1463 depends on !X86_PAE 1464 bool "2G/2G user/kernel split (for full 2G low memory)" 1465 config VMSPLIT_1G 1466 bool "1G/3G user/kernel split" 1467endchoice 1468 1469config PAGE_OFFSET 1470 hex 1471 default 0xB0000000 if VMSPLIT_3G_OPT 1472 default 0x80000000 if VMSPLIT_2G 1473 default 0x78000000 if VMSPLIT_2G_OPT 1474 default 0x40000000 if VMSPLIT_1G 1475 default 0xC0000000 1476 depends on X86_32 1477 1478config HIGHMEM 1479 def_bool y 1480 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1481 1482config X86_PAE 1483 bool "PAE (Physical Address Extension) Support" 1484 depends on X86_32 && !HIGHMEM4G 1485 select PHYS_ADDR_T_64BIT 1486 select SWIOTLB 1487 help 1488 PAE is required for NX support, and furthermore enables 1489 larger swapspace support for non-overcommit purposes. It 1490 has the cost of more pagetable lookup overhead, and also 1491 consumes more pagetable space per process. 1492 1493config X86_5LEVEL 1494 bool "Enable 5-level page tables support" 1495 default y 1496 select DYNAMIC_MEMORY_LAYOUT 1497 select SPARSEMEM_VMEMMAP 1498 depends on X86_64 1499 help 1500 5-level paging enables access to larger address space: 1501 up to 128 PiB of virtual address space and 4 PiB of 1502 physical address space. 1503 1504 It will be supported by future Intel CPUs. 1505 1506 A kernel with the option enabled can be booted on machines that 1507 support 4- or 5-level paging. 1508 1509 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1510 information. 1511 1512 Say N if unsure. 1513 1514config X86_DIRECT_GBPAGES 1515 def_bool y 1516 depends on X86_64 1517 help 1518 Certain kernel features effectively disable kernel 1519 linear 1 GB mappings (even if the CPU otherwise 1520 supports them), so don't confuse the user by printing 1521 that we have them enabled. 1522 1523config X86_CPA_STATISTICS 1524 bool "Enable statistic for Change Page Attribute" 1525 depends on DEBUG_FS 1526 help 1527 Expose statistics about the Change Page Attribute mechanism, which 1528 helps to determine the effectiveness of preserving large and huge 1529 page mappings when mapping protections are changed. 1530 1531config X86_MEM_ENCRYPT 1532 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1533 select DYNAMIC_PHYSICAL_MASK 1534 def_bool n 1535 1536config AMD_MEM_ENCRYPT 1537 bool "AMD Secure Memory Encryption (SME) support" 1538 depends on X86_64 && CPU_SUP_AMD 1539 depends on EFI_STUB 1540 select DMA_COHERENT_POOL 1541 select ARCH_USE_MEMREMAP_PROT 1542 select INSTRUCTION_DECODER 1543 select ARCH_HAS_CC_PLATFORM 1544 select X86_MEM_ENCRYPT 1545 select UNACCEPTED_MEMORY 1546 help 1547 Say yes to enable support for the encryption of system memory. 1548 This requires an AMD processor that supports Secure Memory 1549 Encryption (SME). 1550 1551config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1552 bool "Activate AMD Secure Memory Encryption (SME) by default" 1553 depends on AMD_MEM_ENCRYPT 1554 help 1555 Say yes to have system memory encrypted by default if running on 1556 an AMD processor that supports Secure Memory Encryption (SME). 1557 1558 If set to Y, then the encryption of system memory can be 1559 deactivated with the mem_encrypt=off command line option. 1560 1561 If set to N, then the encryption of system memory can be 1562 activated with the mem_encrypt=on command line option. 1563 1564# Common NUMA Features 1565config NUMA 1566 bool "NUMA Memory Allocation and Scheduler Support" 1567 depends on SMP 1568 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1569 default y if X86_BIGSMP 1570 select USE_PERCPU_NUMA_NODE_ID 1571 help 1572 Enable NUMA (Non-Uniform Memory Access) support. 1573 1574 The kernel will try to allocate memory used by a CPU on the 1575 local memory controller of the CPU and add some more 1576 NUMA awareness to the kernel. 1577 1578 For 64-bit this is recommended if the system is Intel Core i7 1579 (or later), AMD Opteron, or EM64T NUMA. 1580 1581 For 32-bit this is only needed if you boot a 32-bit 1582 kernel on a 64-bit NUMA platform. 1583 1584 Otherwise, you should say N. 1585 1586config AMD_NUMA 1587 def_bool y 1588 prompt "Old style AMD Opteron NUMA detection" 1589 depends on X86_64 && NUMA && PCI 1590 help 1591 Enable AMD NUMA node topology detection. You should say Y here if 1592 you have a multi processor AMD system. This uses an old method to 1593 read the NUMA configuration directly from the builtin Northbridge 1594 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1595 which also takes priority if both are compiled in. 1596 1597config X86_64_ACPI_NUMA 1598 def_bool y 1599 prompt "ACPI NUMA detection" 1600 depends on X86_64 && NUMA && ACPI && PCI 1601 select ACPI_NUMA 1602 help 1603 Enable ACPI SRAT based node topology detection. 1604 1605config NUMA_EMU 1606 bool "NUMA emulation" 1607 depends on NUMA 1608 help 1609 Enable NUMA emulation. A flat machine will be split 1610 into virtual nodes when booted with "numa=fake=N", where N is the 1611 number of nodes. This is only useful for debugging. 1612 1613config NODES_SHIFT 1614 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1615 range 1 10 1616 default "10" if MAXSMP 1617 default "6" if X86_64 1618 default "3" 1619 depends on NUMA 1620 help 1621 Specify the maximum number of NUMA Nodes available on the target 1622 system. Increases memory reserved to accommodate various tables. 1623 1624config ARCH_FLATMEM_ENABLE 1625 def_bool y 1626 depends on X86_32 && !NUMA 1627 1628config ARCH_SPARSEMEM_ENABLE 1629 def_bool y 1630 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1631 select SPARSEMEM_STATIC if X86_32 1632 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1633 1634config ARCH_SPARSEMEM_DEFAULT 1635 def_bool X86_64 || (NUMA && X86_32) 1636 1637config ARCH_SELECT_MEMORY_MODEL 1638 def_bool y 1639 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1640 1641config ARCH_MEMORY_PROBE 1642 bool "Enable sysfs memory/probe interface" 1643 depends on MEMORY_HOTPLUG 1644 help 1645 This option enables a sysfs memory/probe interface for testing. 1646 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1647 If you are unsure how to answer this question, answer N. 1648 1649config ARCH_PROC_KCORE_TEXT 1650 def_bool y 1651 depends on X86_64 && PROC_KCORE 1652 1653config ILLEGAL_POINTER_VALUE 1654 hex 1655 default 0 if X86_32 1656 default 0xdead000000000000 if X86_64 1657 1658config X86_PMEM_LEGACY_DEVICE 1659 bool 1660 1661config X86_PMEM_LEGACY 1662 tristate "Support non-standard NVDIMMs and ADR protected memory" 1663 depends on PHYS_ADDR_T_64BIT 1664 depends on BLK_DEV 1665 select X86_PMEM_LEGACY_DEVICE 1666 select NUMA_KEEP_MEMINFO if NUMA 1667 select LIBNVDIMM 1668 help 1669 Treat memory marked using the non-standard e820 type of 12 as used 1670 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1671 The kernel will offer these regions to the 'pmem' driver so 1672 they can be used for persistent storage. 1673 1674 Say Y if unsure. 1675 1676config HIGHPTE 1677 bool "Allocate 3rd-level pagetables from highmem" 1678 depends on HIGHMEM 1679 help 1680 The VM uses one page table entry for each page of physical memory. 1681 For systems with a lot of RAM, this can be wasteful of precious 1682 low memory. Setting this option will put user-space page table 1683 entries in high memory. 1684 1685config X86_CHECK_BIOS_CORRUPTION 1686 bool "Check for low memory corruption" 1687 help 1688 Periodically check for memory corruption in low memory, which 1689 is suspected to be caused by BIOS. Even when enabled in the 1690 configuration, it is disabled at runtime. Enable it by 1691 setting "memory_corruption_check=1" on the kernel command 1692 line. By default it scans the low 64k of memory every 60 1693 seconds; see the memory_corruption_check_size and 1694 memory_corruption_check_period parameters in 1695 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1696 1697 When enabled with the default parameters, this option has 1698 almost no overhead, as it reserves a relatively small amount 1699 of memory and scans it infrequently. It both detects corruption 1700 and prevents it from affecting the running system. 1701 1702 It is, however, intended as a diagnostic tool; if repeatable 1703 BIOS-originated corruption always affects the same memory, 1704 you can use memmap= to prevent the kernel from using that 1705 memory. 1706 1707config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1708 bool "Set the default setting of memory_corruption_check" 1709 depends on X86_CHECK_BIOS_CORRUPTION 1710 default y 1711 help 1712 Set whether the default state of memory_corruption_check is 1713 on or off. 1714 1715config MATH_EMULATION 1716 bool 1717 depends on MODIFY_LDT_SYSCALL 1718 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1719 help 1720 Linux can emulate a math coprocessor (used for floating point 1721 operations) if you don't have one. 486DX and Pentium processors have 1722 a math coprocessor built in, 486SX and 386 do not, unless you added 1723 a 487DX or 387, respectively. (The messages during boot time can 1724 give you some hints here ["man dmesg"].) Everyone needs either a 1725 coprocessor or this emulation. 1726 1727 If you don't have a math coprocessor, you need to say Y here; if you 1728 say Y here even though you have a coprocessor, the coprocessor will 1729 be used nevertheless. (This behavior can be changed with the kernel 1730 command line option "no387", which comes handy if your coprocessor 1731 is broken. Try "man bootparam" or see the documentation of your boot 1732 loader (lilo or loadlin) about how to pass options to the kernel at 1733 boot time.) This means that it is a good idea to say Y here if you 1734 intend to use this kernel on different machines. 1735 1736 More information about the internals of the Linux math coprocessor 1737 emulation can be found in <file:arch/x86/math-emu/README>. 1738 1739 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1740 kernel, it won't hurt. 1741 1742config MTRR 1743 def_bool y 1744 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1745 help 1746 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1747 the Memory Type Range Registers (MTRRs) may be used to control 1748 processor access to memory ranges. This is most useful if you have 1749 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1750 allows bus write transfers to be combined into a larger transfer 1751 before bursting over the PCI/AGP bus. This can increase performance 1752 of image write operations 2.5 times or more. Saying Y here creates a 1753 /proc/mtrr file which may be used to manipulate your processor's 1754 MTRRs. Typically the X server should use this. 1755 1756 This code has a reasonably generic interface so that similar 1757 control registers on other processors can be easily supported 1758 as well: 1759 1760 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1761 Registers (ARRs) which provide a similar functionality to MTRRs. For 1762 these, the ARRs are used to emulate the MTRRs. 1763 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1764 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1765 write-combining. All of these processors are supported by this code 1766 and it makes sense to say Y here if you have one of them. 1767 1768 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1769 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1770 can lead to all sorts of problems, so it's good to say Y here. 1771 1772 You can safely say Y even if your machine doesn't have MTRRs, you'll 1773 just add about 9 KB to your kernel. 1774 1775 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1776 1777config MTRR_SANITIZER 1778 def_bool y 1779 prompt "MTRR cleanup support" 1780 depends on MTRR 1781 help 1782 Convert MTRR layout from continuous to discrete, so X drivers can 1783 add writeback entries. 1784 1785 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1786 The largest mtrr entry size for a continuous block can be set with 1787 mtrr_chunk_size. 1788 1789 If unsure, say Y. 1790 1791config MTRR_SANITIZER_ENABLE_DEFAULT 1792 int "MTRR cleanup enable value (0-1)" 1793 range 0 1 1794 default "0" 1795 depends on MTRR_SANITIZER 1796 help 1797 Enable mtrr cleanup default value 1798 1799config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1800 int "MTRR cleanup spare reg num (0-7)" 1801 range 0 7 1802 default "1" 1803 depends on MTRR_SANITIZER 1804 help 1805 mtrr cleanup spare entries default, it can be changed via 1806 mtrr_spare_reg_nr=N on the kernel command line. 1807 1808config X86_PAT 1809 def_bool y 1810 prompt "x86 PAT support" if EXPERT 1811 depends on MTRR 1812 help 1813 Use PAT attributes to setup page level cache control. 1814 1815 PATs are the modern equivalents of MTRRs and are much more 1816 flexible than MTRRs. 1817 1818 Say N here if you see bootup problems (boot crash, boot hang, 1819 spontaneous reboots) or a non-working video driver. 1820 1821 If unsure, say Y. 1822 1823config ARCH_USES_PG_UNCACHED 1824 def_bool y 1825 depends on X86_PAT 1826 1827config X86_UMIP 1828 def_bool y 1829 prompt "User Mode Instruction Prevention" if EXPERT 1830 help 1831 User Mode Instruction Prevention (UMIP) is a security feature in 1832 some x86 processors. If enabled, a general protection fault is 1833 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1834 executed in user mode. These instructions unnecessarily expose 1835 information about the hardware state. 1836 1837 The vast majority of applications do not use these instructions. 1838 For the very few that do, software emulation is provided in 1839 specific cases in protected and virtual-8086 modes. Emulated 1840 results are dummy. 1841 1842config CC_HAS_IBT 1843 # GCC >= 9 and binutils >= 2.29 1844 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1845 # Clang/LLVM >= 14 1846 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1847 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1848 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1849 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1850 $(as-instr,endbr64) 1851 1852config X86_KERNEL_IBT 1853 prompt "Indirect Branch Tracking" 1854 def_bool y 1855 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1856 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1857 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1858 select OBJTOOL 1859 help 1860 Build the kernel with support for Indirect Branch Tracking, a 1861 hardware support course-grain forward-edge Control Flow Integrity 1862 protection. It enforces that all indirect calls must land on 1863 an ENDBR instruction, as such, the compiler will instrument the 1864 code with them to make this happen. 1865 1866 In addition to building the kernel with IBT, seal all functions that 1867 are not indirect call targets, avoiding them ever becoming one. 1868 1869 This requires LTO like objtool runs and will slow down the build. It 1870 does significantly reduce the number of ENDBR instructions in the 1871 kernel image. 1872 1873config X86_INTEL_MEMORY_PROTECTION_KEYS 1874 prompt "Memory Protection Keys" 1875 def_bool y 1876 # Note: only available in 64-bit mode 1877 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1878 select ARCH_USES_HIGH_VMA_FLAGS 1879 select ARCH_HAS_PKEYS 1880 help 1881 Memory Protection Keys provides a mechanism for enforcing 1882 page-based protections, but without requiring modification of the 1883 page tables when an application changes protection domains. 1884 1885 For details, see Documentation/core-api/protection-keys.rst 1886 1887 If unsure, say y. 1888 1889choice 1890 prompt "TSX enable mode" 1891 depends on CPU_SUP_INTEL 1892 default X86_INTEL_TSX_MODE_OFF 1893 help 1894 Intel's TSX (Transactional Synchronization Extensions) feature 1895 allows to optimize locking protocols through lock elision which 1896 can lead to a noticeable performance boost. 1897 1898 On the other hand it has been shown that TSX can be exploited 1899 to form side channel attacks (e.g. TAA) and chances are there 1900 will be more of those attacks discovered in the future. 1901 1902 Therefore TSX is not enabled by default (aka tsx=off). An admin 1903 might override this decision by tsx=on the command line parameter. 1904 Even with TSX enabled, the kernel will attempt to enable the best 1905 possible TAA mitigation setting depending on the microcode available 1906 for the particular machine. 1907 1908 This option allows to set the default tsx mode between tsx=on, =off 1909 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1910 details. 1911 1912 Say off if not sure, auto if TSX is in use but it should be used on safe 1913 platforms or on if TSX is in use and the security aspect of tsx is not 1914 relevant. 1915 1916config X86_INTEL_TSX_MODE_OFF 1917 bool "off" 1918 help 1919 TSX is disabled if possible - equals to tsx=off command line parameter. 1920 1921config X86_INTEL_TSX_MODE_ON 1922 bool "on" 1923 help 1924 TSX is always enabled on TSX capable HW - equals the tsx=on command 1925 line parameter. 1926 1927config X86_INTEL_TSX_MODE_AUTO 1928 bool "auto" 1929 help 1930 TSX is enabled on TSX capable HW that is believed to be safe against 1931 side channel attacks- equals the tsx=auto command line parameter. 1932endchoice 1933 1934config X86_SGX 1935 bool "Software Guard eXtensions (SGX)" 1936 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1937 depends on CRYPTO=y 1938 depends on CRYPTO_SHA256=y 1939 select MMU_NOTIFIER 1940 select NUMA_KEEP_MEMINFO if NUMA 1941 select XARRAY_MULTI 1942 help 1943 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1944 that can be used by applications to set aside private regions of code 1945 and data, referred to as enclaves. An enclave's private memory can 1946 only be accessed by code running within the enclave. Accesses from 1947 outside the enclave, including other enclaves, are disallowed by 1948 hardware. 1949 1950 If unsure, say N. 1951 1952config EFI 1953 bool "EFI runtime service support" 1954 depends on ACPI 1955 select UCS2_STRING 1956 select EFI_RUNTIME_WRAPPERS 1957 select ARCH_USE_MEMREMAP_PROT 1958 help 1959 This enables the kernel to use EFI runtime services that are 1960 available (such as the EFI variable services). 1961 1962 This option is only useful on systems that have EFI firmware. 1963 In addition, you should use the latest ELILO loader available 1964 at <http://elilo.sourceforge.net> in order to take advantage 1965 of EFI runtime services. However, even with this option, the 1966 resultant kernel should continue to boot on existing non-EFI 1967 platforms. 1968 1969config EFI_STUB 1970 bool "EFI stub support" 1971 depends on EFI 1972 select RELOCATABLE 1973 help 1974 This kernel feature allows a bzImage to be loaded directly 1975 by EFI firmware without the use of a bootloader. 1976 1977 See Documentation/admin-guide/efi-stub.rst for more information. 1978 1979config EFI_HANDOVER_PROTOCOL 1980 bool "EFI handover protocol (DEPRECATED)" 1981 depends on EFI_STUB 1982 default y 1983 help 1984 Select this in order to include support for the deprecated EFI 1985 handover protocol, which defines alternative entry points into the 1986 EFI stub. This is a practice that has no basis in the UEFI 1987 specification, and requires a priori knowledge on the part of the 1988 bootloader about Linux/x86 specific ways of passing the command line 1989 and initrd, and where in memory those assets may be loaded. 1990 1991 If in doubt, say Y. Even though the corresponding support is not 1992 present in upstream GRUB or other bootloaders, most distros build 1993 GRUB with numerous downstream patches applied, and may rely on the 1994 handover protocol as as result. 1995 1996config EFI_MIXED 1997 bool "EFI mixed-mode support" 1998 depends on EFI_STUB && X86_64 1999 help 2000 Enabling this feature allows a 64-bit kernel to be booted 2001 on a 32-bit firmware, provided that your CPU supports 64-bit 2002 mode. 2003 2004 Note that it is not possible to boot a mixed-mode enabled 2005 kernel via the EFI boot stub - a bootloader that supports 2006 the EFI handover protocol must be used. 2007 2008 If unsure, say N. 2009 2010config EFI_FAKE_MEMMAP 2011 bool "Enable EFI fake memory map" 2012 depends on EFI 2013 help 2014 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2015 this parameter, you can add arbitrary attribute to specific memory 2016 range by updating original (firmware provided) EFI memmap. This is 2017 useful for debugging of EFI memmap related feature, e.g., Address 2018 Range Mirroring feature. 2019 2020config EFI_MAX_FAKE_MEM 2021 int "maximum allowable number of ranges in efi_fake_mem boot option" 2022 depends on EFI_FAKE_MEMMAP 2023 range 1 128 2024 default 8 2025 help 2026 Maximum allowable number of ranges in efi_fake_mem boot option. 2027 Ranges can be set up to this value using comma-separated list. 2028 The default value is 8. 2029 2030config EFI_RUNTIME_MAP 2031 bool "Export EFI runtime maps to sysfs" if EXPERT 2032 depends on EFI 2033 default KEXEC_CORE 2034 help 2035 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2036 That memory map is required by the 2nd kernel to set up EFI virtual 2037 mappings after kexec, but can also be used for debugging purposes. 2038 2039 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2040 2041source "kernel/Kconfig.hz" 2042 2043config KEXEC 2044 bool "kexec system call" 2045 select KEXEC_CORE 2046 help 2047 kexec is a system call that implements the ability to shutdown your 2048 current kernel, and to start another kernel. It is like a reboot 2049 but it is independent of the system firmware. And like a reboot 2050 you can start any kernel with it, not just Linux. 2051 2052 The name comes from the similarity to the exec system call. 2053 2054 It is an ongoing process to be certain the hardware in a machine 2055 is properly shutdown, so do not be surprised if this code does not 2056 initially work for you. As of this writing the exact hardware 2057 interface is strongly in flux, so no good recommendation can be 2058 made. 2059 2060config KEXEC_FILE 2061 bool "kexec file based system call" 2062 select KEXEC_CORE 2063 select HAVE_IMA_KEXEC if IMA 2064 depends on X86_64 2065 depends on CRYPTO=y 2066 depends on CRYPTO_SHA256=y 2067 help 2068 This is new version of kexec system call. This system call is 2069 file based and takes file descriptors as system call argument 2070 for kernel and initramfs as opposed to list of segments as 2071 accepted by previous system call. 2072 2073config ARCH_HAS_KEXEC_PURGATORY 2074 def_bool KEXEC_FILE 2075 2076config KEXEC_SIG 2077 bool "Verify kernel signature during kexec_file_load() syscall" 2078 depends on KEXEC_FILE 2079 help 2080 2081 This option makes the kexec_file_load() syscall check for a valid 2082 signature of the kernel image. The image can still be loaded without 2083 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2084 there's a signature that we can check, then it must be valid. 2085 2086 In addition to this option, you need to enable signature 2087 verification for the corresponding kernel image type being 2088 loaded in order for this to work. 2089 2090config KEXEC_SIG_FORCE 2091 bool "Require a valid signature in kexec_file_load() syscall" 2092 depends on KEXEC_SIG 2093 help 2094 This option makes kernel signature verification mandatory for 2095 the kexec_file_load() syscall. 2096 2097config KEXEC_BZIMAGE_VERIFY_SIG 2098 bool "Enable bzImage signature verification support" 2099 depends on KEXEC_SIG 2100 depends on SIGNED_PE_FILE_VERIFICATION 2101 select SYSTEM_TRUSTED_KEYRING 2102 help 2103 Enable bzImage signature verification support. 2104 2105config CRASH_DUMP 2106 bool "kernel crash dumps" 2107 depends on X86_64 || (X86_32 && HIGHMEM) 2108 help 2109 Generate crash dump after being started by kexec. 2110 This should be normally only set in special crash dump kernels 2111 which are loaded in the main kernel with kexec-tools into 2112 a specially reserved region and then later executed after 2113 a crash by kdump/kexec. The crash dump kernel must be compiled 2114 to a memory address not used by the main kernel or BIOS using 2115 PHYSICAL_START, or it must be built as a relocatable image 2116 (CONFIG_RELOCATABLE=y). 2117 For more details see Documentation/admin-guide/kdump/kdump.rst 2118 2119config KEXEC_JUMP 2120 bool "kexec jump" 2121 depends on KEXEC && HIBERNATION 2122 help 2123 Jump between original kernel and kexeced kernel and invoke 2124 code in physical address mode via KEXEC 2125 2126config PHYSICAL_START 2127 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2128 default "0x1000000" 2129 help 2130 This gives the physical address where the kernel is loaded. 2131 2132 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2133 bzImage will decompress itself to above physical address and 2134 run from there. Otherwise, bzImage will run from the address where 2135 it has been loaded by the boot loader and will ignore above physical 2136 address. 2137 2138 In normal kdump cases one does not have to set/change this option 2139 as now bzImage can be compiled as a completely relocatable image 2140 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2141 address. This option is mainly useful for the folks who don't want 2142 to use a bzImage for capturing the crash dump and want to use a 2143 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2144 to be specifically compiled to run from a specific memory area 2145 (normally a reserved region) and this option comes handy. 2146 2147 So if you are using bzImage for capturing the crash dump, 2148 leave the value here unchanged to 0x1000000 and set 2149 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2150 for capturing the crash dump change this value to start of 2151 the reserved region. In other words, it can be set based on 2152 the "X" value as specified in the "crashkernel=YM@XM" 2153 command line boot parameter passed to the panic-ed 2154 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2155 for more details about crash dumps. 2156 2157 Usage of bzImage for capturing the crash dump is recommended as 2158 one does not have to build two kernels. Same kernel can be used 2159 as production kernel and capture kernel. Above option should have 2160 gone away after relocatable bzImage support is introduced. But it 2161 is present because there are users out there who continue to use 2162 vmlinux for dump capture. This option should go away down the 2163 line. 2164 2165 Don't change this unless you know what you are doing. 2166 2167config RELOCATABLE 2168 bool "Build a relocatable kernel" 2169 default y 2170 help 2171 This builds a kernel image that retains relocation information 2172 so it can be loaded someplace besides the default 1MB. 2173 The relocations tend to make the kernel binary about 10% larger, 2174 but are discarded at runtime. 2175 2176 One use is for the kexec on panic case where the recovery kernel 2177 must live at a different physical address than the primary 2178 kernel. 2179 2180 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2181 it has been loaded at and the compile time physical address 2182 (CONFIG_PHYSICAL_START) is used as the minimum location. 2183 2184config RANDOMIZE_BASE 2185 bool "Randomize the address of the kernel image (KASLR)" 2186 depends on RELOCATABLE 2187 default y 2188 help 2189 In support of Kernel Address Space Layout Randomization (KASLR), 2190 this randomizes the physical address at which the kernel image 2191 is decompressed and the virtual address where the kernel 2192 image is mapped, as a security feature that deters exploit 2193 attempts relying on knowledge of the location of kernel 2194 code internals. 2195 2196 On 64-bit, the kernel physical and virtual addresses are 2197 randomized separately. The physical address will be anywhere 2198 between 16MB and the top of physical memory (up to 64TB). The 2199 virtual address will be randomized from 16MB up to 1GB (9 bits 2200 of entropy). Note that this also reduces the memory space 2201 available to kernel modules from 1.5GB to 1GB. 2202 2203 On 32-bit, the kernel physical and virtual addresses are 2204 randomized together. They will be randomized from 16MB up to 2205 512MB (8 bits of entropy). 2206 2207 Entropy is generated using the RDRAND instruction if it is 2208 supported. If RDTSC is supported, its value is mixed into 2209 the entropy pool as well. If neither RDRAND nor RDTSC are 2210 supported, then entropy is read from the i8254 timer. The 2211 usable entropy is limited by the kernel being built using 2212 2GB addressing, and that PHYSICAL_ALIGN must be at a 2213 minimum of 2MB. As a result, only 10 bits of entropy are 2214 theoretically possible, but the implementations are further 2215 limited due to memory layouts. 2216 2217 If unsure, say Y. 2218 2219# Relocation on x86 needs some additional build support 2220config X86_NEED_RELOCS 2221 def_bool y 2222 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2223 2224config PHYSICAL_ALIGN 2225 hex "Alignment value to which kernel should be aligned" 2226 default "0x200000" 2227 range 0x2000 0x1000000 if X86_32 2228 range 0x200000 0x1000000 if X86_64 2229 help 2230 This value puts the alignment restrictions on physical address 2231 where kernel is loaded and run from. Kernel is compiled for an 2232 address which meets above alignment restriction. 2233 2234 If bootloader loads the kernel at a non-aligned address and 2235 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2236 address aligned to above value and run from there. 2237 2238 If bootloader loads the kernel at a non-aligned address and 2239 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2240 load address and decompress itself to the address it has been 2241 compiled for and run from there. The address for which kernel is 2242 compiled already meets above alignment restrictions. Hence the 2243 end result is that kernel runs from a physical address meeting 2244 above alignment restrictions. 2245 2246 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2247 this value must be a multiple of 0x200000. 2248 2249 Don't change this unless you know what you are doing. 2250 2251config DYNAMIC_MEMORY_LAYOUT 2252 bool 2253 help 2254 This option makes base addresses of vmalloc and vmemmap as well as 2255 __PAGE_OFFSET movable during boot. 2256 2257config RANDOMIZE_MEMORY 2258 bool "Randomize the kernel memory sections" 2259 depends on X86_64 2260 depends on RANDOMIZE_BASE 2261 select DYNAMIC_MEMORY_LAYOUT 2262 default RANDOMIZE_BASE 2263 help 2264 Randomizes the base virtual address of kernel memory sections 2265 (physical memory mapping, vmalloc & vmemmap). This security feature 2266 makes exploits relying on predictable memory locations less reliable. 2267 2268 The order of allocations remains unchanged. Entropy is generated in 2269 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2270 configuration have in average 30,000 different possible virtual 2271 addresses for each memory section. 2272 2273 If unsure, say Y. 2274 2275config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2276 hex "Physical memory mapping padding" if EXPERT 2277 depends on RANDOMIZE_MEMORY 2278 default "0xa" if MEMORY_HOTPLUG 2279 default "0x0" 2280 range 0x1 0x40 if MEMORY_HOTPLUG 2281 range 0x0 0x40 2282 help 2283 Define the padding in terabytes added to the existing physical 2284 memory size during kernel memory randomization. It is useful 2285 for memory hotplug support but reduces the entropy available for 2286 address randomization. 2287 2288 If unsure, leave at the default value. 2289 2290config ADDRESS_MASKING 2291 bool "Linear Address Masking support" 2292 depends on X86_64 2293 help 2294 Linear Address Masking (LAM) modifies the checking that is applied 2295 to 64-bit linear addresses, allowing software to use of the 2296 untranslated address bits for metadata. 2297 2298 The capability can be used for efficient address sanitizers (ASAN) 2299 implementation and for optimizations in JITs. 2300 2301config HOTPLUG_CPU 2302 def_bool y 2303 depends on SMP 2304 2305config COMPAT_VDSO 2306 def_bool n 2307 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2308 depends on COMPAT_32 2309 help 2310 Certain buggy versions of glibc will crash if they are 2311 presented with a 32-bit vDSO that is not mapped at the address 2312 indicated in its segment table. 2313 2314 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2315 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2316 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2317 the only released version with the bug, but OpenSUSE 9 2318 contains a buggy "glibc 2.3.2". 2319 2320 The symptom of the bug is that everything crashes on startup, saying: 2321 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2322 2323 Saying Y here changes the default value of the vdso32 boot 2324 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2325 This works around the glibc bug but hurts performance. 2326 2327 If unsure, say N: if you are compiling your own kernel, you 2328 are unlikely to be using a buggy version of glibc. 2329 2330choice 2331 prompt "vsyscall table for legacy applications" 2332 depends on X86_64 2333 default LEGACY_VSYSCALL_XONLY 2334 help 2335 Legacy user code that does not know how to find the vDSO expects 2336 to be able to issue three syscalls by calling fixed addresses in 2337 kernel space. Since this location is not randomized with ASLR, 2338 it can be used to assist security vulnerability exploitation. 2339 2340 This setting can be changed at boot time via the kernel command 2341 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2342 is deprecated and can only be enabled using the kernel command 2343 line. 2344 2345 On a system with recent enough glibc (2.14 or newer) and no 2346 static binaries, you can say None without a performance penalty 2347 to improve security. 2348 2349 If unsure, select "Emulate execution only". 2350 2351 config LEGACY_VSYSCALL_XONLY 2352 bool "Emulate execution only" 2353 help 2354 The kernel traps and emulates calls into the fixed vsyscall 2355 address mapping and does not allow reads. This 2356 configuration is recommended when userspace might use the 2357 legacy vsyscall area but support for legacy binary 2358 instrumentation of legacy code is not needed. It mitigates 2359 certain uses of the vsyscall area as an ASLR-bypassing 2360 buffer. 2361 2362 config LEGACY_VSYSCALL_NONE 2363 bool "None" 2364 help 2365 There will be no vsyscall mapping at all. This will 2366 eliminate any risk of ASLR bypass due to the vsyscall 2367 fixed address mapping. Attempts to use the vsyscalls 2368 will be reported to dmesg, so that either old or 2369 malicious userspace programs can be identified. 2370 2371endchoice 2372 2373config CMDLINE_BOOL 2374 bool "Built-in kernel command line" 2375 help 2376 Allow for specifying boot arguments to the kernel at 2377 build time. On some systems (e.g. embedded ones), it is 2378 necessary or convenient to provide some or all of the 2379 kernel boot arguments with the kernel itself (that is, 2380 to not rely on the boot loader to provide them.) 2381 2382 To compile command line arguments into the kernel, 2383 set this option to 'Y', then fill in the 2384 boot arguments in CONFIG_CMDLINE. 2385 2386 Systems with fully functional boot loaders (i.e. non-embedded) 2387 should leave this option set to 'N'. 2388 2389config CMDLINE 2390 string "Built-in kernel command string" 2391 depends on CMDLINE_BOOL 2392 default "" 2393 help 2394 Enter arguments here that should be compiled into the kernel 2395 image and used at boot time. If the boot loader provides a 2396 command line at boot time, it is appended to this string to 2397 form the full kernel command line, when the system boots. 2398 2399 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2400 change this behavior. 2401 2402 In most cases, the command line (whether built-in or provided 2403 by the boot loader) should specify the device for the root 2404 file system. 2405 2406config CMDLINE_OVERRIDE 2407 bool "Built-in command line overrides boot loader arguments" 2408 depends on CMDLINE_BOOL && CMDLINE != "" 2409 help 2410 Set this option to 'Y' to have the kernel ignore the boot loader 2411 command line, and use ONLY the built-in command line. 2412 2413 This is used to work around broken boot loaders. This should 2414 be set to 'N' under normal conditions. 2415 2416config MODIFY_LDT_SYSCALL 2417 bool "Enable the LDT (local descriptor table)" if EXPERT 2418 default y 2419 help 2420 Linux can allow user programs to install a per-process x86 2421 Local Descriptor Table (LDT) using the modify_ldt(2) system 2422 call. This is required to run 16-bit or segmented code such as 2423 DOSEMU or some Wine programs. It is also used by some very old 2424 threading libraries. 2425 2426 Enabling this feature adds a small amount of overhead to 2427 context switches and increases the low-level kernel attack 2428 surface. Disabling it removes the modify_ldt(2) system call. 2429 2430 Saying 'N' here may make sense for embedded or server kernels. 2431 2432config STRICT_SIGALTSTACK_SIZE 2433 bool "Enforce strict size checking for sigaltstack" 2434 depends on DYNAMIC_SIGFRAME 2435 help 2436 For historical reasons MINSIGSTKSZ is a constant which became 2437 already too small with AVX512 support. Add a mechanism to 2438 enforce strict checking of the sigaltstack size against the 2439 real size of the FPU frame. This option enables the check 2440 by default. It can also be controlled via the kernel command 2441 line option 'strict_sas_size' independent of this config 2442 switch. Enabling it might break existing applications which 2443 allocate a too small sigaltstack but 'work' because they 2444 never get a signal delivered. 2445 2446 Say 'N' unless you want to really enforce this check. 2447 2448source "kernel/livepatch/Kconfig" 2449 2450endmenu 2451 2452config CC_HAS_SLS 2453 def_bool $(cc-option,-mharden-sls=all) 2454 2455config CC_HAS_RETURN_THUNK 2456 def_bool $(cc-option,-mfunction-return=thunk-extern) 2457 2458config CC_HAS_ENTRY_PADDING 2459 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2460 2461config FUNCTION_PADDING_CFI 2462 int 2463 default 59 if FUNCTION_ALIGNMENT_64B 2464 default 27 if FUNCTION_ALIGNMENT_32B 2465 default 11 if FUNCTION_ALIGNMENT_16B 2466 default 3 if FUNCTION_ALIGNMENT_8B 2467 default 0 2468 2469# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2470# except Kconfig can't do arithmetic :/ 2471config FUNCTION_PADDING_BYTES 2472 int 2473 default FUNCTION_PADDING_CFI if CFI_CLANG 2474 default FUNCTION_ALIGNMENT 2475 2476config CALL_PADDING 2477 def_bool n 2478 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2479 select FUNCTION_ALIGNMENT_16B 2480 2481config FINEIBT 2482 def_bool y 2483 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2484 select CALL_PADDING 2485 2486config HAVE_CALL_THUNKS 2487 def_bool y 2488 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2489 2490config CALL_THUNKS 2491 def_bool n 2492 select CALL_PADDING 2493 2494config PREFIX_SYMBOLS 2495 def_bool y 2496 depends on CALL_PADDING && !CFI_CLANG 2497 2498menuconfig SPECULATION_MITIGATIONS 2499 bool "Mitigations for speculative execution vulnerabilities" 2500 default y 2501 help 2502 Say Y here to enable options which enable mitigations for 2503 speculative execution hardware vulnerabilities. 2504 2505 If you say N, all mitigations will be disabled. You really 2506 should know what you are doing to say so. 2507 2508if SPECULATION_MITIGATIONS 2509 2510config PAGE_TABLE_ISOLATION 2511 bool "Remove the kernel mapping in user mode" 2512 default y 2513 depends on (X86_64 || X86_PAE) 2514 help 2515 This feature reduces the number of hardware side channels by 2516 ensuring that the majority of kernel addresses are not mapped 2517 into userspace. 2518 2519 See Documentation/arch/x86/pti.rst for more details. 2520 2521config RETPOLINE 2522 bool "Avoid speculative indirect branches in kernel" 2523 select OBJTOOL if HAVE_OBJTOOL 2524 default y 2525 help 2526 Compile kernel with the retpoline compiler options to guard against 2527 kernel-to-user data leaks by avoiding speculative indirect 2528 branches. Requires a compiler with -mindirect-branch=thunk-extern 2529 support for full protection. The kernel may run slower. 2530 2531config RETHUNK 2532 bool "Enable return-thunks" 2533 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2534 select OBJTOOL if HAVE_OBJTOOL 2535 default y if X86_64 2536 help 2537 Compile the kernel with the return-thunks compiler option to guard 2538 against kernel-to-user data leaks by avoiding return speculation. 2539 Requires a compiler with -mfunction-return=thunk-extern 2540 support for full protection. The kernel may run slower. 2541 2542config CPU_UNRET_ENTRY 2543 bool "Enable UNRET on kernel entry" 2544 depends on CPU_SUP_AMD && RETHUNK && X86_64 2545 default y 2546 help 2547 Compile the kernel with support for the retbleed=unret mitigation. 2548 2549config CALL_DEPTH_TRACKING 2550 bool "Mitigate RSB underflow with call depth tracking" 2551 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2552 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2553 select CALL_THUNKS 2554 default y 2555 help 2556 Compile the kernel with call depth tracking to mitigate the Intel 2557 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2558 mitigation is off by default and needs to be enabled on the 2559 kernel command line via the retbleed=stuff option. For 2560 non-affected systems the overhead of this option is marginal as 2561 the call depth tracking is using run-time generated call thunks 2562 in a compiler generated padding area and call patching. This 2563 increases text size by ~5%. For non affected systems this space 2564 is unused. On affected SKL systems this results in a significant 2565 performance gain over the IBRS mitigation. 2566 2567config CALL_THUNKS_DEBUG 2568 bool "Enable call thunks and call depth tracking debugging" 2569 depends on CALL_DEPTH_TRACKING 2570 select FUNCTION_ALIGNMENT_32B 2571 default n 2572 help 2573 Enable call/ret counters for imbalance detection and build in 2574 a noisy dmesg about callthunks generation and call patching for 2575 trouble shooting. The debug prints need to be enabled on the 2576 kernel command line with 'debug-callthunks'. 2577 Only enable this when you are debugging call thunks as this 2578 creates a noticeable runtime overhead. If unsure say N. 2579 2580config CPU_IBPB_ENTRY 2581 bool "Enable IBPB on kernel entry" 2582 depends on CPU_SUP_AMD && X86_64 2583 default y 2584 help 2585 Compile the kernel with support for the retbleed=ibpb mitigation. 2586 2587config CPU_IBRS_ENTRY 2588 bool "Enable IBRS on kernel entry" 2589 depends on CPU_SUP_INTEL && X86_64 2590 default y 2591 help 2592 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2593 This mitigates both spectre_v2 and retbleed at great cost to 2594 performance. 2595 2596config SLS 2597 bool "Mitigate Straight-Line-Speculation" 2598 depends on CC_HAS_SLS && X86_64 2599 select OBJTOOL if HAVE_OBJTOOL 2600 default n 2601 help 2602 Compile the kernel with straight-line-speculation options to guard 2603 against straight line speculation. The kernel image might be slightly 2604 larger. 2605 2606endif 2607 2608config ARCH_HAS_ADD_PAGES 2609 def_bool y 2610 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2611 2612config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2613 def_bool y 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 X86_X32_ABI 2996 bool "x32 ABI for 64-bit mode" 2997 depends on X86_64 2998 # llvm-objcopy does not convert x86_64 .note.gnu.property or 2999 # compressed debug sections to x86_x32 properly: 3000 # https://github.com/ClangBuiltLinux/linux/issues/514 3001 # https://github.com/ClangBuiltLinux/linux/issues/1141 3002 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3003 help 3004 Include code to run binaries for the x32 native 32-bit ABI 3005 for 64-bit processors. An x32 process gets access to the 3006 full 64-bit register file and wide data path while leaving 3007 pointers at 32 bits for smaller memory footprint. 3008 3009config COMPAT_32 3010 def_bool y 3011 depends on IA32_EMULATION || X86_32 3012 select HAVE_UID16 3013 select OLD_SIGSUSPEND3 3014 3015config COMPAT 3016 def_bool y 3017 depends on IA32_EMULATION || X86_X32_ABI 3018 3019config COMPAT_FOR_U64_ALIGNMENT 3020 def_bool y 3021 depends on COMPAT 3022 3023endmenu 3024 3025config HAVE_ATOMIC_IOMAP 3026 def_bool y 3027 depends on X86_32 3028 3029source "arch/x86/kvm/Kconfig" 3030 3031source "arch/x86/Kconfig.assembler" 3032