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_DAX_VMEMMAP if X86_64 132 select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64 133 select ARCH_WANTS_THP_SWAP if X86_64 134 select ARCH_HAS_PARANOID_L1D_FLUSH 135 select BUILDTIME_TABLE_SORT 136 select CLKEVT_I8253 137 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 138 select CLOCKSOURCE_WATCHDOG 139 # Word-size accesses may read uninitialized data past the trailing \0 140 # in strings and cause false KMSAN reports. 141 select DCACHE_WORD_ACCESS if !KMSAN 142 select DYNAMIC_SIGFRAME 143 select EDAC_ATOMIC_SCRUB 144 select EDAC_SUPPORT 145 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 146 select GENERIC_CLOCKEVENTS_MIN_ADJUST 147 select GENERIC_CMOS_UPDATE 148 select GENERIC_CPU_AUTOPROBE 149 select GENERIC_CPU_VULNERABILITIES 150 select GENERIC_EARLY_IOREMAP 151 select GENERIC_ENTRY 152 select GENERIC_IOMAP 153 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 154 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 155 select GENERIC_IRQ_MIGRATION if SMP 156 select GENERIC_IRQ_PROBE 157 select GENERIC_IRQ_RESERVATION_MODE 158 select GENERIC_IRQ_SHOW 159 select GENERIC_PENDING_IRQ if SMP 160 select GENERIC_PTDUMP 161 select GENERIC_SMP_IDLE_THREAD 162 select GENERIC_TIME_VSYSCALL 163 select GENERIC_GETTIMEOFDAY 164 select GENERIC_VDSO_TIME_NS 165 select GUP_GET_PXX_LOW_HIGH if X86_PAE 166 select HARDIRQS_SW_RESEND 167 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 168 select HAS_IOPORT 169 select HAVE_ACPI_APEI if ACPI 170 select HAVE_ACPI_APEI_NMI if ACPI 171 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 172 select HAVE_ARCH_AUDITSYSCALL 173 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 174 select HAVE_ARCH_HUGE_VMALLOC if X86_64 175 select HAVE_ARCH_JUMP_LABEL 176 select HAVE_ARCH_JUMP_LABEL_RELATIVE 177 select HAVE_ARCH_KASAN if X86_64 178 select HAVE_ARCH_KASAN_VMALLOC if X86_64 179 select HAVE_ARCH_KFENCE 180 select HAVE_ARCH_KMSAN if X86_64 181 select HAVE_ARCH_KGDB 182 select HAVE_ARCH_MMAP_RND_BITS if MMU 183 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 184 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 185 select HAVE_ARCH_PREL32_RELOCATIONS 186 select HAVE_ARCH_SECCOMP_FILTER 187 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 188 select HAVE_ARCH_STACKLEAK 189 select HAVE_ARCH_TRACEHOOK 190 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 191 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 192 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD 193 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD 194 select HAVE_ARCH_VMAP_STACK if X86_64 195 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET 196 select HAVE_ARCH_WITHIN_STACK_FRAMES 197 select HAVE_ASM_MODVERSIONS 198 select HAVE_CMPXCHG_DOUBLE 199 select HAVE_CMPXCHG_LOCAL 200 select HAVE_CONTEXT_TRACKING_USER if X86_64 201 select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER 202 select HAVE_C_RECORDMCOUNT 203 select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL 204 select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT 205 select HAVE_BUILDTIME_MCOUNT_SORT 206 select HAVE_DEBUG_KMEMLEAK 207 select HAVE_DMA_CONTIGUOUS 208 select HAVE_DYNAMIC_FTRACE 209 select HAVE_DYNAMIC_FTRACE_WITH_REGS 210 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 211 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 212 select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 213 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64 214 select HAVE_EBPF_JIT 215 select HAVE_EFFICIENT_UNALIGNED_ACCESS 216 select HAVE_EISA 217 select HAVE_EXIT_THREAD 218 select HAVE_FAST_GUP 219 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 220 select HAVE_FTRACE_MCOUNT_RECORD 221 select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER 222 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) 223 select HAVE_FUNCTION_TRACER 224 select HAVE_GCC_PLUGINS 225 select HAVE_HW_BREAKPOINT 226 select HAVE_IOREMAP_PROT 227 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 228 select HAVE_IRQ_TIME_ACCOUNTING 229 select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL 230 select HAVE_KERNEL_BZIP2 231 select HAVE_KERNEL_GZIP 232 select HAVE_KERNEL_LZ4 233 select HAVE_KERNEL_LZMA 234 select HAVE_KERNEL_LZO 235 select HAVE_KERNEL_XZ 236 select HAVE_KERNEL_ZSTD 237 select HAVE_KPROBES 238 select HAVE_KPROBES_ON_FTRACE 239 select HAVE_FUNCTION_ERROR_INJECTION 240 select HAVE_KRETPROBES 241 select HAVE_RETHOOK 242 select HAVE_KVM 243 select HAVE_LIVEPATCH if X86_64 244 select HAVE_MIXED_BREAKPOINTS_REGS 245 select HAVE_MOD_ARCH_SPECIFIC 246 select HAVE_MOVE_PMD 247 select HAVE_MOVE_PUD 248 select HAVE_NOINSTR_HACK if HAVE_OBJTOOL 249 select HAVE_NMI 250 select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL 251 select HAVE_OBJTOOL if X86_64 252 select HAVE_OPTPROBES 253 select HAVE_PCSPKR_PLATFORM 254 select HAVE_PERF_EVENTS 255 select HAVE_PERF_EVENTS_NMI 256 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 257 select HAVE_PCI 258 select HAVE_PERF_REGS 259 select HAVE_PERF_USER_STACK_DUMP 260 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT 261 select MMU_GATHER_MERGE_VMAS 262 select HAVE_POSIX_CPU_TIMERS_TASK_WORK 263 select HAVE_REGS_AND_STACK_ACCESS_API 264 select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION 265 select HAVE_FUNCTION_ARG_ACCESS_API 266 select HAVE_SETUP_PER_CPU_AREA 267 select HAVE_SOFTIRQ_ON_OWN_STACK 268 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 269 select HAVE_STACK_VALIDATION if HAVE_OBJTOOL 270 select HAVE_STATIC_CALL 271 select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL 272 select HAVE_PREEMPT_DYNAMIC_CALL 273 select HAVE_RSEQ 274 select HAVE_RUST if X86_64 275 select HAVE_SYSCALL_TRACEPOINTS 276 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL 277 select HAVE_UNSTABLE_SCHED_CLOCK 278 select HAVE_USER_RETURN_NOTIFIER 279 select HAVE_GENERIC_VDSO 280 select HOTPLUG_PARALLEL if SMP && X86_64 281 select HOTPLUG_SMT if SMP 282 select HOTPLUG_SPLIT_STARTUP if SMP && X86_32 283 select IRQ_FORCED_THREADING 284 select LOCK_MM_AND_FIND_VMA 285 select NEED_PER_CPU_EMBED_FIRST_CHUNK 286 select NEED_PER_CPU_PAGE_FIRST_CHUNK 287 select NEED_SG_DMA_LENGTH 288 select PCI_DOMAINS if PCI 289 select PCI_LOCKLESS_CONFIG if PCI 290 select PERF_EVENTS 291 select RTC_LIB 292 select RTC_MC146818_LIB 293 select SPARSE_IRQ 294 select SYSCTL_EXCEPTION_TRACE 295 select THREAD_INFO_IN_TASK 296 select TRACE_IRQFLAGS_SUPPORT 297 select TRACE_IRQFLAGS_NMI_SUPPORT 298 select USER_STACKTRACE_SUPPORT 299 select HAVE_ARCH_KCSAN if X86_64 300 select PROC_PID_ARCH_STATUS if PROC_FS 301 select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX 302 select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16 303 select FUNCTION_ALIGNMENT_4B 304 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI 305 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 306 307config INSTRUCTION_DECODER 308 def_bool y 309 depends on KPROBES || PERF_EVENTS || UPROBES 310 311config OUTPUT_FORMAT 312 string 313 default "elf32-i386" if X86_32 314 default "elf64-x86-64" if X86_64 315 316config LOCKDEP_SUPPORT 317 def_bool y 318 319config STACKTRACE_SUPPORT 320 def_bool y 321 322config MMU 323 def_bool y 324 325config ARCH_MMAP_RND_BITS_MIN 326 default 28 if 64BIT 327 default 8 328 329config ARCH_MMAP_RND_BITS_MAX 330 default 32 if 64BIT 331 default 16 332 333config ARCH_MMAP_RND_COMPAT_BITS_MIN 334 default 8 335 336config ARCH_MMAP_RND_COMPAT_BITS_MAX 337 default 16 338 339config SBUS 340 bool 341 342config GENERIC_ISA_DMA 343 def_bool y 344 depends on ISA_DMA_API 345 346config GENERIC_CSUM 347 bool 348 default y if KMSAN || KASAN 349 350config GENERIC_BUG 351 def_bool y 352 depends on BUG 353 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 354 355config GENERIC_BUG_RELATIVE_POINTERS 356 bool 357 358config ARCH_MAY_HAVE_PC_FDC 359 def_bool y 360 depends on ISA_DMA_API 361 362config GENERIC_CALIBRATE_DELAY 363 def_bool y 364 365config ARCH_HAS_CPU_RELAX 366 def_bool y 367 368config ARCH_HIBERNATION_POSSIBLE 369 def_bool y 370 371config ARCH_SUSPEND_POSSIBLE 372 def_bool y 373 374config AUDIT_ARCH 375 def_bool y if X86_64 376 377config KASAN_SHADOW_OFFSET 378 hex 379 depends on KASAN 380 default 0xdffffc0000000000 381 382config HAVE_INTEL_TXT 383 def_bool y 384 depends on INTEL_IOMMU && ACPI 385 386config X86_32_SMP 387 def_bool y 388 depends on X86_32 && SMP 389 390config X86_64_SMP 391 def_bool y 392 depends on X86_64 && SMP 393 394config ARCH_SUPPORTS_UPROBES 395 def_bool y 396 397config FIX_EARLYCON_MEM 398 def_bool y 399 400config DYNAMIC_PHYSICAL_MASK 401 bool 402 403config PGTABLE_LEVELS 404 int 405 default 5 if X86_5LEVEL 406 default 4 if X86_64 407 default 3 if X86_PAE 408 default 2 409 410config CC_HAS_SANE_STACKPROTECTOR 411 bool 412 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT 413 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) 414 help 415 We have to make sure stack protector is unconditionally disabled if 416 the compiler produces broken code or if it does not let us control 417 the segment on 32-bit kernels. 418 419menu "Processor type and features" 420 421config SMP 422 bool "Symmetric multi-processing support" 423 help 424 This enables support for systems with more than one CPU. If you have 425 a system with only one CPU, say N. If you have a system with more 426 than one CPU, say Y. 427 428 If you say N here, the kernel will run on uni- and multiprocessor 429 machines, but will use only one CPU of a multiprocessor machine. If 430 you say Y here, the kernel will run on many, but not all, 431 uniprocessor machines. On a uniprocessor machine, the kernel 432 will run faster if you say N here. 433 434 Note that if you say Y here and choose architecture "586" or 435 "Pentium" under "Processor family", the kernel will not work on 486 436 architectures. Similarly, multiprocessor kernels for the "PPro" 437 architecture may not work on all Pentium based boards. 438 439 People using multiprocessor machines who say Y here should also say 440 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 441 Management" code will be disabled if you say Y here. 442 443 See also <file:Documentation/arch/x86/i386/IO-APIC.rst>, 444 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 445 <http://www.tldp.org/docs.html#howto>. 446 447 If you don't know what to do here, say N. 448 449config X86_X2APIC 450 bool "Support x2apic" 451 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 452 help 453 This enables x2apic support on CPUs that have this feature. 454 455 This allows 32-bit apic IDs (so it can support very large systems), 456 and accesses the local apic via MSRs not via mmio. 457 458 Some Intel systems circa 2022 and later are locked into x2APIC mode 459 and can not fall back to the legacy APIC modes if SGX or TDX are 460 enabled in the BIOS. They will boot with very reduced functionality 461 without enabling this option. 462 463 If you don't know what to do here, say N. 464 465config X86_MPPARSE 466 bool "Enable MPS table" if ACPI 467 default y 468 depends on X86_LOCAL_APIC 469 help 470 For old smp systems that do not have proper acpi support. Newer systems 471 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 472 473config GOLDFISH 474 def_bool y 475 depends on X86_GOLDFISH 476 477config X86_CPU_RESCTRL 478 bool "x86 CPU resource control support" 479 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 480 select KERNFS 481 select PROC_CPU_RESCTRL if PROC_FS 482 help 483 Enable x86 CPU resource control support. 484 485 Provide support for the allocation and monitoring of system resources 486 usage by the CPU. 487 488 Intel calls this Intel Resource Director Technology 489 (Intel(R) RDT). More information about RDT can be found in the 490 Intel x86 Architecture Software Developer Manual. 491 492 AMD calls this AMD Platform Quality of Service (AMD QoS). 493 More information about AMD QoS can be found in the AMD64 Technology 494 Platform Quality of Service Extensions manual. 495 496 Say N if unsure. 497 498if X86_32 499config X86_BIGSMP 500 bool "Support for big SMP systems with more than 8 CPUs" 501 depends on SMP 502 help 503 This option is needed for the systems that have more than 8 CPUs. 504 505config X86_EXTENDED_PLATFORM 506 bool "Support for extended (non-PC) x86 platforms" 507 default y 508 help 509 If you disable this option then the kernel will only support 510 standard PC platforms. (which covers the vast majority of 511 systems out there.) 512 513 If you enable this option then you'll be able to select support 514 for the following (non-PC) 32 bit x86 platforms: 515 Goldfish (Android emulator) 516 AMD Elan 517 RDC R-321x SoC 518 SGI 320/540 (Visual Workstation) 519 STA2X11-based (e.g. Northville) 520 Moorestown MID devices 521 522 If you have one of these systems, or if you want to build a 523 generic distribution kernel, say Y here - otherwise say N. 524endif # X86_32 525 526if X86_64 527config X86_EXTENDED_PLATFORM 528 bool "Support for extended (non-PC) x86 platforms" 529 default y 530 help 531 If you disable this option then the kernel will only support 532 standard PC platforms. (which covers the vast majority of 533 systems out there.) 534 535 If you enable this option then you'll be able to select support 536 for the following (non-PC) 64 bit x86 platforms: 537 Numascale NumaChip 538 ScaleMP vSMP 539 SGI Ultraviolet 540 541 If you have one of these systems, or if you want to build a 542 generic distribution kernel, say Y here - otherwise say N. 543endif # X86_64 544# This is an alphabetically sorted list of 64 bit extended platforms 545# Please maintain the alphabetic order if and when there are additions 546config X86_NUMACHIP 547 bool "Numascale NumaChip" 548 depends on X86_64 549 depends on X86_EXTENDED_PLATFORM 550 depends on NUMA 551 depends on SMP 552 depends on X86_X2APIC 553 depends on PCI_MMCONFIG 554 help 555 Adds support for Numascale NumaChip large-SMP systems. Needed to 556 enable more than ~168 cores. 557 If you don't have one of these, you should say N here. 558 559config X86_VSMP 560 bool "ScaleMP vSMP" 561 select HYPERVISOR_GUEST 562 select PARAVIRT 563 depends on X86_64 && PCI 564 depends on X86_EXTENDED_PLATFORM 565 depends on SMP 566 help 567 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 568 supposed to run on these EM64T-based machines. Only choose this option 569 if you have one of these machines. 570 571config X86_UV 572 bool "SGI Ultraviolet" 573 depends on X86_64 574 depends on X86_EXTENDED_PLATFORM 575 depends on NUMA 576 depends on EFI 577 depends on KEXEC_CORE 578 depends on X86_X2APIC 579 depends on PCI 580 help 581 This option is needed in order to support SGI Ultraviolet systems. 582 If you don't have one of these, you should say N here. 583 584# Following is an alphabetically sorted list of 32 bit extended platforms 585# Please maintain the alphabetic order if and when there are additions 586 587config X86_GOLDFISH 588 bool "Goldfish (Virtual Platform)" 589 depends on X86_EXTENDED_PLATFORM 590 help 591 Enable support for the Goldfish virtual platform used primarily 592 for Android development. Unless you are building for the Android 593 Goldfish emulator say N here. 594 595config X86_INTEL_CE 596 bool "CE4100 TV platform" 597 depends on PCI 598 depends on PCI_GODIRECT 599 depends on X86_IO_APIC 600 depends on X86_32 601 depends on X86_EXTENDED_PLATFORM 602 select X86_REBOOTFIXUPS 603 select OF 604 select OF_EARLY_FLATTREE 605 help 606 Select for the Intel CE media processor (CE4100) SOC. 607 This option compiles in support for the CE4100 SOC for settop 608 boxes and media devices. 609 610config X86_INTEL_MID 611 bool "Intel MID platform support" 612 depends on X86_EXTENDED_PLATFORM 613 depends on X86_PLATFORM_DEVICES 614 depends on PCI 615 depends on X86_64 || (PCI_GOANY && X86_32) 616 depends on X86_IO_APIC 617 select I2C 618 select DW_APB_TIMER 619 select INTEL_SCU_PCI 620 help 621 Select to build a kernel capable of supporting Intel MID (Mobile 622 Internet Device) platform systems which do not have the PCI legacy 623 interfaces. If you are building for a PC class system say N here. 624 625 Intel MID platforms are based on an Intel processor and chipset which 626 consume less power than most of the x86 derivatives. 627 628config X86_INTEL_QUARK 629 bool "Intel Quark platform support" 630 depends on X86_32 631 depends on X86_EXTENDED_PLATFORM 632 depends on X86_PLATFORM_DEVICES 633 depends on X86_TSC 634 depends on PCI 635 depends on PCI_GOANY 636 depends on X86_IO_APIC 637 select IOSF_MBI 638 select INTEL_IMR 639 select COMMON_CLK 640 help 641 Select to include support for Quark X1000 SoC. 642 Say Y here if you have a Quark based system such as the Arduino 643 compatible Intel Galileo. 644 645config X86_INTEL_LPSS 646 bool "Intel Low Power Subsystem Support" 647 depends on X86 && ACPI && PCI 648 select COMMON_CLK 649 select PINCTRL 650 select IOSF_MBI 651 help 652 Select to build support for Intel Low Power Subsystem such as 653 found on Intel Lynxpoint PCH. Selecting this option enables 654 things like clock tree (common clock framework) and pincontrol 655 which are needed by the LPSS peripheral drivers. 656 657config X86_AMD_PLATFORM_DEVICE 658 bool "AMD ACPI2Platform devices support" 659 depends on ACPI 660 select COMMON_CLK 661 select PINCTRL 662 help 663 Select to interpret AMD specific ACPI device to platform device 664 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 665 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 666 implemented under PINCTRL subsystem. 667 668config IOSF_MBI 669 tristate "Intel SoC IOSF Sideband support for SoC platforms" 670 depends on PCI 671 help 672 This option enables sideband register access support for Intel SoC 673 platforms. On these platforms the IOSF sideband is used in lieu of 674 MSR's for some register accesses, mostly but not limited to thermal 675 and power. Drivers may query the availability of this device to 676 determine if they need the sideband in order to work on these 677 platforms. The sideband is available on the following SoC products. 678 This list is not meant to be exclusive. 679 - BayTrail 680 - Braswell 681 - Quark 682 683 You should say Y if you are running a kernel on one of these SoC's. 684 685config IOSF_MBI_DEBUG 686 bool "Enable IOSF sideband access through debugfs" 687 depends on IOSF_MBI && DEBUG_FS 688 help 689 Select this option to expose the IOSF sideband access registers (MCR, 690 MDR, MCRX) through debugfs to write and read register information from 691 different units on the SoC. This is most useful for obtaining device 692 state information for debug and analysis. As this is a general access 693 mechanism, users of this option would have specific knowledge of the 694 device they want to access. 695 696 If you don't require the option or are in doubt, say N. 697 698config X86_RDC321X 699 bool "RDC R-321x SoC" 700 depends on X86_32 701 depends on X86_EXTENDED_PLATFORM 702 select M486 703 select X86_REBOOTFIXUPS 704 help 705 This option is needed for RDC R-321x system-on-chip, also known 706 as R-8610-(G). 707 If you don't have one of these chips, you should say N here. 708 709config X86_32_NON_STANDARD 710 bool "Support non-standard 32-bit SMP architectures" 711 depends on X86_32 && SMP 712 depends on X86_EXTENDED_PLATFORM 713 help 714 This option compiles in the bigsmp and STA2X11 default 715 subarchitectures. It is intended for a generic binary 716 kernel. If you select them all, kernel will probe it one by 717 one and will fallback to default. 718 719# Alphabetically sorted list of Non standard 32 bit platforms 720 721config X86_SUPPORTS_MEMORY_FAILURE 722 def_bool y 723 # MCE code calls memory_failure(): 724 depends on X86_MCE 725 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 726 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 727 depends on X86_64 || !SPARSEMEM 728 select ARCH_SUPPORTS_MEMORY_FAILURE 729 730config STA2X11 731 bool "STA2X11 Companion Chip Support" 732 depends on X86_32_NON_STANDARD && PCI 733 select SWIOTLB 734 select MFD_STA2X11 735 select GPIOLIB 736 help 737 This adds support for boards based on the STA2X11 IO-Hub, 738 a.k.a. "ConneXt". The chip is used in place of the standard 739 PC chipset, so all "standard" peripherals are missing. If this 740 option is selected the kernel will still be able to boot on 741 standard PC machines. 742 743config X86_32_IRIS 744 tristate "Eurobraille/Iris poweroff module" 745 depends on X86_32 746 help 747 The Iris machines from EuroBraille do not have APM or ACPI support 748 to shut themselves down properly. A special I/O sequence is 749 needed to do so, which is what this module does at 750 kernel shutdown. 751 752 This is only for Iris machines from EuroBraille. 753 754 If unused, say N. 755 756config SCHED_OMIT_FRAME_POINTER 757 def_bool y 758 prompt "Single-depth WCHAN output" 759 depends on X86 760 help 761 Calculate simpler /proc/<PID>/wchan values. If this option 762 is disabled then wchan values will recurse back to the 763 caller function. This provides more accurate wchan values, 764 at the expense of slightly more scheduling overhead. 765 766 If in doubt, say "Y". 767 768menuconfig HYPERVISOR_GUEST 769 bool "Linux guest support" 770 help 771 Say Y here to enable options for running Linux under various hyper- 772 visors. This option enables basic hypervisor detection and platform 773 setup. 774 775 If you say N, all options in this submenu will be skipped and 776 disabled, and Linux guest support won't be built in. 777 778if HYPERVISOR_GUEST 779 780config PARAVIRT 781 bool "Enable paravirtualization code" 782 depends on HAVE_STATIC_CALL 783 help 784 This changes the kernel so it can modify itself when it is run 785 under a hypervisor, potentially improving performance significantly 786 over full virtualization. However, when run without a hypervisor 787 the kernel is theoretically slower and slightly larger. 788 789config PARAVIRT_XXL 790 bool 791 792config PARAVIRT_DEBUG 793 bool "paravirt-ops debugging" 794 depends on PARAVIRT && DEBUG_KERNEL 795 help 796 Enable to debug paravirt_ops internals. Specifically, BUG if 797 a paravirt_op is missing when it is called. 798 799config PARAVIRT_SPINLOCKS 800 bool "Paravirtualization layer for spinlocks" 801 depends on PARAVIRT && SMP 802 help 803 Paravirtualized spinlocks allow a pvops backend to replace the 804 spinlock implementation with something virtualization-friendly 805 (for example, block the virtual CPU rather than spinning). 806 807 It has a minimal impact on native kernels and gives a nice performance 808 benefit on paravirtualized KVM / Xen kernels. 809 810 If you are unsure how to answer this question, answer Y. 811 812config X86_HV_CALLBACK_VECTOR 813 def_bool n 814 815source "arch/x86/xen/Kconfig" 816 817config KVM_GUEST 818 bool "KVM Guest support (including kvmclock)" 819 depends on PARAVIRT 820 select PARAVIRT_CLOCK 821 select ARCH_CPUIDLE_HALTPOLL 822 select X86_HV_CALLBACK_VECTOR 823 default y 824 help 825 This option enables various optimizations for running under the KVM 826 hypervisor. It includes a paravirtualized clock, so that instead 827 of relying on a PIT (or probably other) emulation by the 828 underlying device model, the host provides the guest with 829 timing infrastructure such as time of day, and system time 830 831config ARCH_CPUIDLE_HALTPOLL 832 def_bool n 833 prompt "Disable host haltpoll when loading haltpoll driver" 834 help 835 If virtualized under KVM, disable host haltpoll. 836 837config PVH 838 bool "Support for running PVH guests" 839 help 840 This option enables the PVH entry point for guest virtual machines 841 as specified in the x86/HVM direct boot ABI. 842 843config PARAVIRT_TIME_ACCOUNTING 844 bool "Paravirtual steal time accounting" 845 depends on PARAVIRT 846 help 847 Select this option to enable fine granularity task steal time 848 accounting. Time spent executing other tasks in parallel with 849 the current vCPU is discounted from the vCPU power. To account for 850 that, there can be a small performance impact. 851 852 If in doubt, say N here. 853 854config PARAVIRT_CLOCK 855 bool 856 857config JAILHOUSE_GUEST 858 bool "Jailhouse non-root cell support" 859 depends on X86_64 && PCI 860 select X86_PM_TIMER 861 help 862 This option allows to run Linux as guest in a Jailhouse non-root 863 cell. You can leave this option disabled if you only want to start 864 Jailhouse and run Linux afterwards in the root cell. 865 866config ACRN_GUEST 867 bool "ACRN Guest support" 868 depends on X86_64 869 select X86_HV_CALLBACK_VECTOR 870 help 871 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 872 a flexible, lightweight reference open-source hypervisor, built with 873 real-time and safety-criticality in mind. It is built for embedded 874 IOT with small footprint and real-time features. More details can be 875 found in https://projectacrn.org/. 876 877config INTEL_TDX_GUEST 878 bool "Intel TDX (Trust Domain Extensions) - Guest Support" 879 depends on X86_64 && CPU_SUP_INTEL 880 depends on X86_X2APIC 881 depends on EFI_STUB 882 select ARCH_HAS_CC_PLATFORM 883 select X86_MEM_ENCRYPT 884 select X86_MCE 885 select UNACCEPTED_MEMORY 886 help 887 Support running as a guest under Intel TDX. Without this support, 888 the guest kernel can not boot or run under TDX. 889 TDX includes memory encryption and integrity capabilities 890 which protect the confidentiality and integrity of guest 891 memory contents and CPU state. TDX guests are protected from 892 some attacks from the VMM. 893 894endif # HYPERVISOR_GUEST 895 896source "arch/x86/Kconfig.cpu" 897 898config HPET_TIMER 899 def_bool X86_64 900 prompt "HPET Timer Support" if X86_32 901 help 902 Use the IA-PC HPET (High Precision Event Timer) to manage 903 time in preference to the PIT and RTC, if a HPET is 904 present. 905 HPET is the next generation timer replacing legacy 8254s. 906 The HPET provides a stable time base on SMP 907 systems, unlike the TSC, but it is more expensive to access, 908 as it is off-chip. The interface used is documented 909 in the HPET spec, revision 1. 910 911 You can safely choose Y here. However, HPET will only be 912 activated if the platform and the BIOS support this feature. 913 Otherwise the 8254 will be used for timing services. 914 915 Choose N to continue using the legacy 8254 timer. 916 917config HPET_EMULATE_RTC 918 def_bool y 919 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 920 921# Mark as expert because too many people got it wrong. 922# The code disables itself when not needed. 923config DMI 924 default y 925 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 926 bool "Enable DMI scanning" if EXPERT 927 help 928 Enabled scanning of DMI to identify machine quirks. Say Y 929 here unless you have verified that your setup is not 930 affected by entries in the DMI blacklist. Required by PNP 931 BIOS code. 932 933config GART_IOMMU 934 bool "Old AMD GART IOMMU support" 935 select DMA_OPS 936 select IOMMU_HELPER 937 select SWIOTLB 938 depends on X86_64 && PCI && AMD_NB 939 help 940 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 941 GART based hardware IOMMUs. 942 943 The GART supports full DMA access for devices with 32-bit access 944 limitations, on systems with more than 3 GB. This is usually needed 945 for USB, sound, many IDE/SATA chipsets and some other devices. 946 947 Newer systems typically have a modern AMD IOMMU, supported via 948 the CONFIG_AMD_IOMMU=y config option. 949 950 In normal configurations this driver is only active when needed: 951 there's more than 3 GB of memory and the system contains a 952 32-bit limited device. 953 954 If unsure, say Y. 955 956config BOOT_VESA_SUPPORT 957 bool 958 help 959 If true, at least one selected framebuffer driver can take advantage 960 of VESA video modes set at an early boot stage via the vga= parameter. 961 962config MAXSMP 963 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 964 depends on X86_64 && SMP && DEBUG_KERNEL 965 select CPUMASK_OFFSTACK 966 help 967 Enable maximum number of CPUS and NUMA Nodes for this architecture. 968 If unsure, say N. 969 970# 971# The maximum number of CPUs supported: 972# 973# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 974# and which can be configured interactively in the 975# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 976# 977# The ranges are different on 32-bit and 64-bit kernels, depending on 978# hardware capabilities and scalability features of the kernel. 979# 980# ( If MAXSMP is enabled we just use the highest possible value and disable 981# interactive configuration. ) 982# 983 984config NR_CPUS_RANGE_BEGIN 985 int 986 default NR_CPUS_RANGE_END if MAXSMP 987 default 1 if !SMP 988 default 2 989 990config NR_CPUS_RANGE_END 991 int 992 depends on X86_32 993 default 64 if SMP && X86_BIGSMP 994 default 8 if SMP && !X86_BIGSMP 995 default 1 if !SMP 996 997config NR_CPUS_RANGE_END 998 int 999 depends on X86_64 1000 default 8192 if SMP && CPUMASK_OFFSTACK 1001 default 512 if SMP && !CPUMASK_OFFSTACK 1002 default 1 if !SMP 1003 1004config NR_CPUS_DEFAULT 1005 int 1006 depends on X86_32 1007 default 32 if X86_BIGSMP 1008 default 8 if SMP 1009 default 1 if !SMP 1010 1011config NR_CPUS_DEFAULT 1012 int 1013 depends on X86_64 1014 default 8192 if MAXSMP 1015 default 64 if SMP 1016 default 1 if !SMP 1017 1018config NR_CPUS 1019 int "Maximum number of CPUs" if SMP && !MAXSMP 1020 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1021 default NR_CPUS_DEFAULT 1022 help 1023 This allows you to specify the maximum number of CPUs which this 1024 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1025 supported value is 8192, otherwise the maximum value is 512. The 1026 minimum value which makes sense is 2. 1027 1028 This is purely to save memory: each supported CPU adds about 8KB 1029 to the kernel image. 1030 1031config SCHED_CLUSTER 1032 bool "Cluster scheduler support" 1033 depends on SMP 1034 default y 1035 help 1036 Cluster scheduler support improves the CPU scheduler's decision 1037 making when dealing with machines that have clusters of CPUs. 1038 Cluster usually means a couple of CPUs which are placed closely 1039 by sharing mid-level caches, last-level cache tags or internal 1040 busses. 1041 1042config SCHED_SMT 1043 def_bool y if SMP 1044 1045config SCHED_MC 1046 def_bool y 1047 prompt "Multi-core scheduler support" 1048 depends on SMP 1049 help 1050 Multi-core scheduler support improves the CPU scheduler's decision 1051 making when dealing with multi-core CPU chips at a cost of slightly 1052 increased overhead in some places. If unsure say N here. 1053 1054config SCHED_MC_PRIO 1055 bool "CPU core priorities scheduler support" 1056 depends on SCHED_MC && CPU_SUP_INTEL 1057 select X86_INTEL_PSTATE 1058 select CPU_FREQ 1059 default y 1060 help 1061 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1062 core ordering determined at manufacturing time, which allows 1063 certain cores to reach higher turbo frequencies (when running 1064 single threaded workloads) than others. 1065 1066 Enabling this kernel feature teaches the scheduler about 1067 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1068 scheduler's CPU selection logic accordingly, so that higher 1069 overall system performance can be achieved. 1070 1071 This feature will have no effect on CPUs without this feature. 1072 1073 If unsure say Y here. 1074 1075config UP_LATE_INIT 1076 def_bool y 1077 depends on !SMP && X86_LOCAL_APIC 1078 1079config X86_UP_APIC 1080 bool "Local APIC support on uniprocessors" if !PCI_MSI 1081 default PCI_MSI 1082 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1083 help 1084 A local APIC (Advanced Programmable Interrupt Controller) is an 1085 integrated interrupt controller in the CPU. If you have a single-CPU 1086 system which has a processor with a local APIC, you can say Y here to 1087 enable and use it. If you say Y here even though your machine doesn't 1088 have a local APIC, then the kernel will still run with no slowdown at 1089 all. The local APIC supports CPU-generated self-interrupts (timer, 1090 performance counters), and the NMI watchdog which detects hard 1091 lockups. 1092 1093config X86_UP_IOAPIC 1094 bool "IO-APIC support on uniprocessors" 1095 depends on X86_UP_APIC 1096 help 1097 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1098 SMP-capable replacement for PC-style interrupt controllers. Most 1099 SMP systems and many recent uniprocessor systems have one. 1100 1101 If you have a single-CPU system with an IO-APIC, you can say Y here 1102 to use it. If you say Y here even though your machine doesn't have 1103 an IO-APIC, then the kernel will still run with no slowdown at all. 1104 1105config X86_LOCAL_APIC 1106 def_bool y 1107 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1108 select IRQ_DOMAIN_HIERARCHY 1109 1110config X86_IO_APIC 1111 def_bool y 1112 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1113 1114config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1115 bool "Reroute for broken boot IRQs" 1116 depends on X86_IO_APIC 1117 help 1118 This option enables a workaround that fixes a source of 1119 spurious interrupts. This is recommended when threaded 1120 interrupt handling is used on systems where the generation of 1121 superfluous "boot interrupts" cannot be disabled. 1122 1123 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1124 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1125 kernel does during interrupt handling). On chipsets where this 1126 boot IRQ generation cannot be disabled, this workaround keeps 1127 the original IRQ line masked so that only the equivalent "boot 1128 IRQ" is delivered to the CPUs. The workaround also tells the 1129 kernel to set up the IRQ handler on the boot IRQ line. In this 1130 way only one interrupt is delivered to the kernel. Otherwise 1131 the spurious second interrupt may cause the kernel to bring 1132 down (vital) interrupt lines. 1133 1134 Only affects "broken" chipsets. Interrupt sharing may be 1135 increased on these systems. 1136 1137config X86_MCE 1138 bool "Machine Check / overheating reporting" 1139 select GENERIC_ALLOCATOR 1140 default y 1141 help 1142 Machine Check support allows the processor to notify the 1143 kernel if it detects a problem (e.g. overheating, data corruption). 1144 The action the kernel takes depends on the severity of the problem, 1145 ranging from warning messages to halting the machine. 1146 1147config X86_MCELOG_LEGACY 1148 bool "Support for deprecated /dev/mcelog character device" 1149 depends on X86_MCE 1150 help 1151 Enable support for /dev/mcelog which is needed by the old mcelog 1152 userspace logging daemon. Consider switching to the new generation 1153 rasdaemon solution. 1154 1155config X86_MCE_INTEL 1156 def_bool y 1157 prompt "Intel MCE features" 1158 depends on X86_MCE && X86_LOCAL_APIC 1159 help 1160 Additional support for intel specific MCE features such as 1161 the thermal monitor. 1162 1163config X86_MCE_AMD 1164 def_bool y 1165 prompt "AMD MCE features" 1166 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1167 help 1168 Additional support for AMD specific MCE features such as 1169 the DRAM Error Threshold. 1170 1171config X86_ANCIENT_MCE 1172 bool "Support for old Pentium 5 / WinChip machine checks" 1173 depends on X86_32 && X86_MCE 1174 help 1175 Include support for machine check handling on old Pentium 5 or WinChip 1176 systems. These typically need to be enabled explicitly on the command 1177 line. 1178 1179config X86_MCE_THRESHOLD 1180 depends on X86_MCE_AMD || X86_MCE_INTEL 1181 def_bool y 1182 1183config X86_MCE_INJECT 1184 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1185 tristate "Machine check injector support" 1186 help 1187 Provide support for injecting machine checks for testing purposes. 1188 If you don't know what a machine check is and you don't do kernel 1189 QA it is safe to say n. 1190 1191source "arch/x86/events/Kconfig" 1192 1193config X86_LEGACY_VM86 1194 bool "Legacy VM86 support" 1195 depends on X86_32 1196 help 1197 This option allows user programs to put the CPU into V8086 1198 mode, which is an 80286-era approximation of 16-bit real mode. 1199 1200 Some very old versions of X and/or vbetool require this option 1201 for user mode setting. Similarly, DOSEMU will use it if 1202 available to accelerate real mode DOS programs. However, any 1203 recent version of DOSEMU, X, or vbetool should be fully 1204 functional even without kernel VM86 support, as they will all 1205 fall back to software emulation. Nevertheless, if you are using 1206 a 16-bit DOS program where 16-bit performance matters, vm86 1207 mode might be faster than emulation and you might want to 1208 enable this option. 1209 1210 Note that any app that works on a 64-bit kernel is unlikely to 1211 need this option, as 64-bit kernels don't, and can't, support 1212 V8086 mode. This option is also unrelated to 16-bit protected 1213 mode and is not needed to run most 16-bit programs under Wine. 1214 1215 Enabling this option increases the complexity of the kernel 1216 and slows down exception handling a tiny bit. 1217 1218 If unsure, say N here. 1219 1220config VM86 1221 bool 1222 default X86_LEGACY_VM86 1223 1224config X86_16BIT 1225 bool "Enable support for 16-bit segments" if EXPERT 1226 default y 1227 depends on MODIFY_LDT_SYSCALL 1228 help 1229 This option is required by programs like Wine to run 16-bit 1230 protected mode legacy code on x86 processors. Disabling 1231 this option saves about 300 bytes on i386, or around 6K text 1232 plus 16K runtime memory on x86-64, 1233 1234config X86_ESPFIX32 1235 def_bool y 1236 depends on X86_16BIT && X86_32 1237 1238config X86_ESPFIX64 1239 def_bool y 1240 depends on X86_16BIT && X86_64 1241 1242config X86_VSYSCALL_EMULATION 1243 bool "Enable vsyscall emulation" if EXPERT 1244 default y 1245 depends on X86_64 1246 help 1247 This enables emulation of the legacy vsyscall page. Disabling 1248 it is roughly equivalent to booting with vsyscall=none, except 1249 that it will also disable the helpful warning if a program 1250 tries to use a vsyscall. With this option set to N, offending 1251 programs will just segfault, citing addresses of the form 1252 0xffffffffff600?00. 1253 1254 This option is required by many programs built before 2013, and 1255 care should be used even with newer programs if set to N. 1256 1257 Disabling this option saves about 7K of kernel size and 1258 possibly 4K of additional runtime pagetable memory. 1259 1260config X86_IOPL_IOPERM 1261 bool "IOPERM and IOPL Emulation" 1262 default y 1263 help 1264 This enables the ioperm() and iopl() syscalls which are necessary 1265 for legacy applications. 1266 1267 Legacy IOPL support is an overbroad mechanism which allows user 1268 space aside of accessing all 65536 I/O ports also to disable 1269 interrupts. To gain this access the caller needs CAP_SYS_RAWIO 1270 capabilities and permission from potentially active security 1271 modules. 1272 1273 The emulation restricts the functionality of the syscall to 1274 only allowing the full range I/O port access, but prevents the 1275 ability to disable interrupts from user space which would be 1276 granted if the hardware IOPL mechanism would be used. 1277 1278config TOSHIBA 1279 tristate "Toshiba Laptop support" 1280 depends on X86_32 1281 help 1282 This adds a driver to safely access the System Management Mode of 1283 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1284 not work on models with a Phoenix BIOS. The System Management Mode 1285 is used to set the BIOS and power saving options on Toshiba portables. 1286 1287 For information on utilities to make use of this driver see the 1288 Toshiba Linux utilities web site at: 1289 <http://www.buzzard.org.uk/toshiba/>. 1290 1291 Say Y if you intend to run this kernel on a Toshiba portable. 1292 Say N otherwise. 1293 1294config X86_REBOOTFIXUPS 1295 bool "Enable X86 board specific fixups for reboot" 1296 depends on X86_32 1297 help 1298 This enables chipset and/or board specific fixups to be done 1299 in order to get reboot to work correctly. This is only needed on 1300 some combinations of hardware and BIOS. The symptom, for which 1301 this config is intended, is when reboot ends with a stalled/hung 1302 system. 1303 1304 Currently, the only fixup is for the Geode machines using 1305 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1306 1307 Say Y if you want to enable the fixup. Currently, it's safe to 1308 enable this option even if you don't need it. 1309 Say N otherwise. 1310 1311config MICROCODE 1312 bool "CPU microcode loading support" 1313 default y 1314 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1315 help 1316 If you say Y here, you will be able to update the microcode on 1317 Intel and AMD processors. The Intel support is for the IA32 family, 1318 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1319 AMD support is for families 0x10 and later. You will obviously need 1320 the actual microcode binary data itself which is not shipped with 1321 the Linux kernel. 1322 1323 The preferred method to load microcode from a detached initrd is described 1324 in Documentation/arch/x86/microcode.rst. For that you need to enable 1325 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1326 initrd for microcode blobs. 1327 1328 In addition, you can build the microcode into the kernel. For that you 1329 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1330 config option. 1331 1332config MICROCODE_INTEL 1333 bool "Intel microcode loading support" 1334 depends on CPU_SUP_INTEL && MICROCODE 1335 default MICROCODE 1336 help 1337 This options enables microcode patch loading support for Intel 1338 processors. 1339 1340 For the current Intel microcode data package go to 1341 <https://downloadcenter.intel.com> and search for 1342 'Linux Processor Microcode Data File'. 1343 1344config MICROCODE_AMD 1345 bool "AMD microcode loading support" 1346 depends on CPU_SUP_AMD && MICROCODE 1347 help 1348 If you select this option, microcode patch loading support for AMD 1349 processors will be enabled. 1350 1351config MICROCODE_LATE_LOADING 1352 bool "Late microcode loading (DANGEROUS)" 1353 default n 1354 depends on MICROCODE 1355 help 1356 Loading microcode late, when the system is up and executing instructions 1357 is a tricky business and should be avoided if possible. Just the sequence 1358 of synchronizing all cores and SMT threads is one fragile dance which does 1359 not guarantee that cores might not softlock after the loading. Therefore, 1360 use this at your own risk. Late loading taints the kernel too. 1361 1362config X86_MSR 1363 tristate "/dev/cpu/*/msr - Model-specific register support" 1364 help 1365 This device gives privileged processes access to the x86 1366 Model-Specific Registers (MSRs). It is a character device with 1367 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1368 MSR accesses are directed to a specific CPU on multi-processor 1369 systems. 1370 1371config X86_CPUID 1372 tristate "/dev/cpu/*/cpuid - CPU information support" 1373 help 1374 This device gives processes access to the x86 CPUID instruction to 1375 be executed on a specific processor. It is a character device 1376 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1377 /dev/cpu/31/cpuid. 1378 1379choice 1380 prompt "High Memory Support" 1381 default HIGHMEM4G 1382 depends on X86_32 1383 1384config NOHIGHMEM 1385 bool "off" 1386 help 1387 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1388 However, the address space of 32-bit x86 processors is only 4 1389 Gigabytes large. That means that, if you have a large amount of 1390 physical memory, not all of it can be "permanently mapped" by the 1391 kernel. The physical memory that's not permanently mapped is called 1392 "high memory". 1393 1394 If you are compiling a kernel which will never run on a machine with 1395 more than 1 Gigabyte total physical RAM, answer "off" here (default 1396 choice and suitable for most users). This will result in a "3GB/1GB" 1397 split: 3GB are mapped so that each process sees a 3GB virtual memory 1398 space and the remaining part of the 4GB virtual memory space is used 1399 by the kernel to permanently map as much physical memory as 1400 possible. 1401 1402 If the machine has between 1 and 4 Gigabytes physical RAM, then 1403 answer "4GB" here. 1404 1405 If more than 4 Gigabytes is used then answer "64GB" here. This 1406 selection turns Intel PAE (Physical Address Extension) mode on. 1407 PAE implements 3-level paging on IA32 processors. PAE is fully 1408 supported by Linux, PAE mode is implemented on all recent Intel 1409 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1410 then the kernel will not boot on CPUs that don't support PAE! 1411 1412 The actual amount of total physical memory will either be 1413 auto detected or can be forced by using a kernel command line option 1414 such as "mem=256M". (Try "man bootparam" or see the documentation of 1415 your boot loader (lilo or loadlin) about how to pass options to the 1416 kernel at boot time.) 1417 1418 If unsure, say "off". 1419 1420config HIGHMEM4G 1421 bool "4GB" 1422 help 1423 Select this if you have a 32-bit processor and between 1 and 4 1424 gigabytes of physical RAM. 1425 1426config HIGHMEM64G 1427 bool "64GB" 1428 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1429 select X86_PAE 1430 help 1431 Select this if you have a 32-bit processor and more than 4 1432 gigabytes of physical RAM. 1433 1434endchoice 1435 1436choice 1437 prompt "Memory split" if EXPERT 1438 default VMSPLIT_3G 1439 depends on X86_32 1440 help 1441 Select the desired split between kernel and user memory. 1442 1443 If the address range available to the kernel is less than the 1444 physical memory installed, the remaining memory will be available 1445 as "high memory". Accessing high memory is a little more costly 1446 than low memory, as it needs to be mapped into the kernel first. 1447 Note that increasing the kernel address space limits the range 1448 available to user programs, making the address space there 1449 tighter. Selecting anything other than the default 3G/1G split 1450 will also likely make your kernel incompatible with binary-only 1451 kernel modules. 1452 1453 If you are not absolutely sure what you are doing, leave this 1454 option alone! 1455 1456 config VMSPLIT_3G 1457 bool "3G/1G user/kernel split" 1458 config VMSPLIT_3G_OPT 1459 depends on !X86_PAE 1460 bool "3G/1G user/kernel split (for full 1G low memory)" 1461 config VMSPLIT_2G 1462 bool "2G/2G user/kernel split" 1463 config VMSPLIT_2G_OPT 1464 depends on !X86_PAE 1465 bool "2G/2G user/kernel split (for full 2G low memory)" 1466 config VMSPLIT_1G 1467 bool "1G/3G user/kernel split" 1468endchoice 1469 1470config PAGE_OFFSET 1471 hex 1472 default 0xB0000000 if VMSPLIT_3G_OPT 1473 default 0x80000000 if VMSPLIT_2G 1474 default 0x78000000 if VMSPLIT_2G_OPT 1475 default 0x40000000 if VMSPLIT_1G 1476 default 0xC0000000 1477 depends on X86_32 1478 1479config HIGHMEM 1480 def_bool y 1481 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1482 1483config X86_PAE 1484 bool "PAE (Physical Address Extension) Support" 1485 depends on X86_32 && !HIGHMEM4G 1486 select PHYS_ADDR_T_64BIT 1487 select SWIOTLB 1488 help 1489 PAE is required for NX support, and furthermore enables 1490 larger swapspace support for non-overcommit purposes. It 1491 has the cost of more pagetable lookup overhead, and also 1492 consumes more pagetable space per process. 1493 1494config X86_5LEVEL 1495 bool "Enable 5-level page tables support" 1496 default y 1497 select DYNAMIC_MEMORY_LAYOUT 1498 select SPARSEMEM_VMEMMAP 1499 depends on X86_64 1500 help 1501 5-level paging enables access to larger address space: 1502 up to 128 PiB of virtual address space and 4 PiB of 1503 physical address space. 1504 1505 It will be supported by future Intel CPUs. 1506 1507 A kernel with the option enabled can be booted on machines that 1508 support 4- or 5-level paging. 1509 1510 See Documentation/arch/x86/x86_64/5level-paging.rst for more 1511 information. 1512 1513 Say N if unsure. 1514 1515config X86_DIRECT_GBPAGES 1516 def_bool y 1517 depends on X86_64 1518 help 1519 Certain kernel features effectively disable kernel 1520 linear 1 GB mappings (even if the CPU otherwise 1521 supports them), so don't confuse the user by printing 1522 that we have them enabled. 1523 1524config X86_CPA_STATISTICS 1525 bool "Enable statistic for Change Page Attribute" 1526 depends on DEBUG_FS 1527 help 1528 Expose statistics about the Change Page Attribute mechanism, which 1529 helps to determine the effectiveness of preserving large and huge 1530 page mappings when mapping protections are changed. 1531 1532config X86_MEM_ENCRYPT 1533 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1534 select DYNAMIC_PHYSICAL_MASK 1535 def_bool n 1536 1537config AMD_MEM_ENCRYPT 1538 bool "AMD Secure Memory Encryption (SME) support" 1539 depends on X86_64 && CPU_SUP_AMD 1540 depends on EFI_STUB 1541 select DMA_COHERENT_POOL 1542 select ARCH_USE_MEMREMAP_PROT 1543 select INSTRUCTION_DECODER 1544 select ARCH_HAS_CC_PLATFORM 1545 select X86_MEM_ENCRYPT 1546 select UNACCEPTED_MEMORY 1547 help 1548 Say yes to enable support for the encryption of system memory. 1549 This requires an AMD processor that supports Secure Memory 1550 Encryption (SME). 1551 1552config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1553 bool "Activate AMD Secure Memory Encryption (SME) by default" 1554 depends on AMD_MEM_ENCRYPT 1555 help 1556 Say yes to have system memory encrypted by default if running on 1557 an AMD processor that supports Secure Memory Encryption (SME). 1558 1559 If set to Y, then the encryption of system memory can be 1560 deactivated with the mem_encrypt=off command line option. 1561 1562 If set to N, then the encryption of system memory can be 1563 activated with the mem_encrypt=on command line option. 1564 1565# Common NUMA Features 1566config NUMA 1567 bool "NUMA Memory Allocation and Scheduler Support" 1568 depends on SMP 1569 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1570 default y if X86_BIGSMP 1571 select USE_PERCPU_NUMA_NODE_ID 1572 help 1573 Enable NUMA (Non-Uniform Memory Access) support. 1574 1575 The kernel will try to allocate memory used by a CPU on the 1576 local memory controller of the CPU and add some more 1577 NUMA awareness to the kernel. 1578 1579 For 64-bit this is recommended if the system is Intel Core i7 1580 (or later), AMD Opteron, or EM64T NUMA. 1581 1582 For 32-bit this is only needed if you boot a 32-bit 1583 kernel on a 64-bit NUMA platform. 1584 1585 Otherwise, you should say N. 1586 1587config AMD_NUMA 1588 def_bool y 1589 prompt "Old style AMD Opteron NUMA detection" 1590 depends on X86_64 && NUMA && PCI 1591 help 1592 Enable AMD NUMA node topology detection. You should say Y here if 1593 you have a multi processor AMD system. This uses an old method to 1594 read the NUMA configuration directly from the builtin Northbridge 1595 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1596 which also takes priority if both are compiled in. 1597 1598config X86_64_ACPI_NUMA 1599 def_bool y 1600 prompt "ACPI NUMA detection" 1601 depends on X86_64 && NUMA && ACPI && PCI 1602 select ACPI_NUMA 1603 help 1604 Enable ACPI SRAT based node topology detection. 1605 1606config NUMA_EMU 1607 bool "NUMA emulation" 1608 depends on NUMA 1609 help 1610 Enable NUMA emulation. A flat machine will be split 1611 into virtual nodes when booted with "numa=fake=N", where N is the 1612 number of nodes. This is only useful for debugging. 1613 1614config NODES_SHIFT 1615 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1616 range 1 10 1617 default "10" if MAXSMP 1618 default "6" if X86_64 1619 default "3" 1620 depends on NUMA 1621 help 1622 Specify the maximum number of NUMA Nodes available on the target 1623 system. Increases memory reserved to accommodate various tables. 1624 1625config ARCH_FLATMEM_ENABLE 1626 def_bool y 1627 depends on X86_32 && !NUMA 1628 1629config ARCH_SPARSEMEM_ENABLE 1630 def_bool y 1631 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1632 select SPARSEMEM_STATIC if X86_32 1633 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1634 1635config ARCH_SPARSEMEM_DEFAULT 1636 def_bool X86_64 || (NUMA && X86_32) 1637 1638config ARCH_SELECT_MEMORY_MODEL 1639 def_bool y 1640 depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE 1641 1642config ARCH_MEMORY_PROBE 1643 bool "Enable sysfs memory/probe interface" 1644 depends on MEMORY_HOTPLUG 1645 help 1646 This option enables a sysfs memory/probe interface for testing. 1647 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1648 If you are unsure how to answer this question, answer N. 1649 1650config ARCH_PROC_KCORE_TEXT 1651 def_bool y 1652 depends on X86_64 && PROC_KCORE 1653 1654config ILLEGAL_POINTER_VALUE 1655 hex 1656 default 0 if X86_32 1657 default 0xdead000000000000 if X86_64 1658 1659config X86_PMEM_LEGACY_DEVICE 1660 bool 1661 1662config X86_PMEM_LEGACY 1663 tristate "Support non-standard NVDIMMs and ADR protected memory" 1664 depends on PHYS_ADDR_T_64BIT 1665 depends on BLK_DEV 1666 select X86_PMEM_LEGACY_DEVICE 1667 select NUMA_KEEP_MEMINFO if NUMA 1668 select LIBNVDIMM 1669 help 1670 Treat memory marked using the non-standard e820 type of 12 as used 1671 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1672 The kernel will offer these regions to the 'pmem' driver so 1673 they can be used for persistent storage. 1674 1675 Say Y if unsure. 1676 1677config HIGHPTE 1678 bool "Allocate 3rd-level pagetables from highmem" 1679 depends on HIGHMEM 1680 help 1681 The VM uses one page table entry for each page of physical memory. 1682 For systems with a lot of RAM, this can be wasteful of precious 1683 low memory. Setting this option will put user-space page table 1684 entries in high memory. 1685 1686config X86_CHECK_BIOS_CORRUPTION 1687 bool "Check for low memory corruption" 1688 help 1689 Periodically check for memory corruption in low memory, which 1690 is suspected to be caused by BIOS. Even when enabled in the 1691 configuration, it is disabled at runtime. Enable it by 1692 setting "memory_corruption_check=1" on the kernel command 1693 line. By default it scans the low 64k of memory every 60 1694 seconds; see the memory_corruption_check_size and 1695 memory_corruption_check_period parameters in 1696 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1697 1698 When enabled with the default parameters, this option has 1699 almost no overhead, as it reserves a relatively small amount 1700 of memory and scans it infrequently. It both detects corruption 1701 and prevents it from affecting the running system. 1702 1703 It is, however, intended as a diagnostic tool; if repeatable 1704 BIOS-originated corruption always affects the same memory, 1705 you can use memmap= to prevent the kernel from using that 1706 memory. 1707 1708config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1709 bool "Set the default setting of memory_corruption_check" 1710 depends on X86_CHECK_BIOS_CORRUPTION 1711 default y 1712 help 1713 Set whether the default state of memory_corruption_check is 1714 on or off. 1715 1716config MATH_EMULATION 1717 bool 1718 depends on MODIFY_LDT_SYSCALL 1719 prompt "Math emulation" if X86_32 && (M486SX || MELAN) 1720 help 1721 Linux can emulate a math coprocessor (used for floating point 1722 operations) if you don't have one. 486DX and Pentium processors have 1723 a math coprocessor built in, 486SX and 386 do not, unless you added 1724 a 487DX or 387, respectively. (The messages during boot time can 1725 give you some hints here ["man dmesg"].) Everyone needs either a 1726 coprocessor or this emulation. 1727 1728 If you don't have a math coprocessor, you need to say Y here; if you 1729 say Y here even though you have a coprocessor, the coprocessor will 1730 be used nevertheless. (This behavior can be changed with the kernel 1731 command line option "no387", which comes handy if your coprocessor 1732 is broken. Try "man bootparam" or see the documentation of your boot 1733 loader (lilo or loadlin) about how to pass options to the kernel at 1734 boot time.) This means that it is a good idea to say Y here if you 1735 intend to use this kernel on different machines. 1736 1737 More information about the internals of the Linux math coprocessor 1738 emulation can be found in <file:arch/x86/math-emu/README>. 1739 1740 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1741 kernel, it won't hurt. 1742 1743config MTRR 1744 def_bool y 1745 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1746 help 1747 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1748 the Memory Type Range Registers (MTRRs) may be used to control 1749 processor access to memory ranges. This is most useful if you have 1750 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1751 allows bus write transfers to be combined into a larger transfer 1752 before bursting over the PCI/AGP bus. This can increase performance 1753 of image write operations 2.5 times or more. Saying Y here creates a 1754 /proc/mtrr file which may be used to manipulate your processor's 1755 MTRRs. Typically the X server should use this. 1756 1757 This code has a reasonably generic interface so that similar 1758 control registers on other processors can be easily supported 1759 as well: 1760 1761 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1762 Registers (ARRs) which provide a similar functionality to MTRRs. For 1763 these, the ARRs are used to emulate the MTRRs. 1764 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1765 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1766 write-combining. All of these processors are supported by this code 1767 and it makes sense to say Y here if you have one of them. 1768 1769 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1770 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1771 can lead to all sorts of problems, so it's good to say Y here. 1772 1773 You can safely say Y even if your machine doesn't have MTRRs, you'll 1774 just add about 9 KB to your kernel. 1775 1776 See <file:Documentation/arch/x86/mtrr.rst> for more information. 1777 1778config MTRR_SANITIZER 1779 def_bool y 1780 prompt "MTRR cleanup support" 1781 depends on MTRR 1782 help 1783 Convert MTRR layout from continuous to discrete, so X drivers can 1784 add writeback entries. 1785 1786 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1787 The largest mtrr entry size for a continuous block can be set with 1788 mtrr_chunk_size. 1789 1790 If unsure, say Y. 1791 1792config MTRR_SANITIZER_ENABLE_DEFAULT 1793 int "MTRR cleanup enable value (0-1)" 1794 range 0 1 1795 default "0" 1796 depends on MTRR_SANITIZER 1797 help 1798 Enable mtrr cleanup default value 1799 1800config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1801 int "MTRR cleanup spare reg num (0-7)" 1802 range 0 7 1803 default "1" 1804 depends on MTRR_SANITIZER 1805 help 1806 mtrr cleanup spare entries default, it can be changed via 1807 mtrr_spare_reg_nr=N on the kernel command line. 1808 1809config X86_PAT 1810 def_bool y 1811 prompt "x86 PAT support" if EXPERT 1812 depends on MTRR 1813 help 1814 Use PAT attributes to setup page level cache control. 1815 1816 PATs are the modern equivalents of MTRRs and are much more 1817 flexible than MTRRs. 1818 1819 Say N here if you see bootup problems (boot crash, boot hang, 1820 spontaneous reboots) or a non-working video driver. 1821 1822 If unsure, say Y. 1823 1824config ARCH_USES_PG_UNCACHED 1825 def_bool y 1826 depends on X86_PAT 1827 1828config X86_UMIP 1829 def_bool y 1830 prompt "User Mode Instruction Prevention" if EXPERT 1831 help 1832 User Mode Instruction Prevention (UMIP) is a security feature in 1833 some x86 processors. If enabled, a general protection fault is 1834 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are 1835 executed in user mode. These instructions unnecessarily expose 1836 information about the hardware state. 1837 1838 The vast majority of applications do not use these instructions. 1839 For the very few that do, software emulation is provided in 1840 specific cases in protected and virtual-8086 modes. Emulated 1841 results are dummy. 1842 1843config CC_HAS_IBT 1844 # GCC >= 9 and binutils >= 2.29 1845 # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654 1846 # Clang/LLVM >= 14 1847 # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f 1848 # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332 1849 def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \ 1850 (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \ 1851 $(as-instr,endbr64) 1852 1853config X86_KERNEL_IBT 1854 prompt "Indirect Branch Tracking" 1855 def_bool y 1856 depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL 1857 # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f 1858 depends on !LD_IS_LLD || LLD_VERSION >= 140000 1859 select OBJTOOL 1860 help 1861 Build the kernel with support for Indirect Branch Tracking, a 1862 hardware support course-grain forward-edge Control Flow Integrity 1863 protection. It enforces that all indirect calls must land on 1864 an ENDBR instruction, as such, the compiler will instrument the 1865 code with them to make this happen. 1866 1867 In addition to building the kernel with IBT, seal all functions that 1868 are not indirect call targets, avoiding them ever becoming one. 1869 1870 This requires LTO like objtool runs and will slow down the build. It 1871 does significantly reduce the number of ENDBR instructions in the 1872 kernel image. 1873 1874config X86_INTEL_MEMORY_PROTECTION_KEYS 1875 prompt "Memory Protection Keys" 1876 def_bool y 1877 # Note: only available in 64-bit mode 1878 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD) 1879 select ARCH_USES_HIGH_VMA_FLAGS 1880 select ARCH_HAS_PKEYS 1881 help 1882 Memory Protection Keys provides a mechanism for enforcing 1883 page-based protections, but without requiring modification of the 1884 page tables when an application changes protection domains. 1885 1886 For details, see Documentation/core-api/protection-keys.rst 1887 1888 If unsure, say y. 1889 1890choice 1891 prompt "TSX enable mode" 1892 depends on CPU_SUP_INTEL 1893 default X86_INTEL_TSX_MODE_OFF 1894 help 1895 Intel's TSX (Transactional Synchronization Extensions) feature 1896 allows to optimize locking protocols through lock elision which 1897 can lead to a noticeable performance boost. 1898 1899 On the other hand it has been shown that TSX can be exploited 1900 to form side channel attacks (e.g. TAA) and chances are there 1901 will be more of those attacks discovered in the future. 1902 1903 Therefore TSX is not enabled by default (aka tsx=off). An admin 1904 might override this decision by tsx=on the command line parameter. 1905 Even with TSX enabled, the kernel will attempt to enable the best 1906 possible TAA mitigation setting depending on the microcode available 1907 for the particular machine. 1908 1909 This option allows to set the default tsx mode between tsx=on, =off 1910 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1911 details. 1912 1913 Say off if not sure, auto if TSX is in use but it should be used on safe 1914 platforms or on if TSX is in use and the security aspect of tsx is not 1915 relevant. 1916 1917config X86_INTEL_TSX_MODE_OFF 1918 bool "off" 1919 help 1920 TSX is disabled if possible - equals to tsx=off command line parameter. 1921 1922config X86_INTEL_TSX_MODE_ON 1923 bool "on" 1924 help 1925 TSX is always enabled on TSX capable HW - equals the tsx=on command 1926 line parameter. 1927 1928config X86_INTEL_TSX_MODE_AUTO 1929 bool "auto" 1930 help 1931 TSX is enabled on TSX capable HW that is believed to be safe against 1932 side channel attacks- equals the tsx=auto command line parameter. 1933endchoice 1934 1935config X86_SGX 1936 bool "Software Guard eXtensions (SGX)" 1937 depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC 1938 depends on CRYPTO=y 1939 depends on CRYPTO_SHA256=y 1940 select MMU_NOTIFIER 1941 select NUMA_KEEP_MEMINFO if NUMA 1942 select XARRAY_MULTI 1943 help 1944 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions 1945 that can be used by applications to set aside private regions of code 1946 and data, referred to as enclaves. An enclave's private memory can 1947 only be accessed by code running within the enclave. Accesses from 1948 outside the enclave, including other enclaves, are disallowed by 1949 hardware. 1950 1951 If unsure, say N. 1952 1953config EFI 1954 bool "EFI runtime service support" 1955 depends on ACPI 1956 select UCS2_STRING 1957 select EFI_RUNTIME_WRAPPERS 1958 select ARCH_USE_MEMREMAP_PROT 1959 help 1960 This enables the kernel to use EFI runtime services that are 1961 available (such as the EFI variable services). 1962 1963 This option is only useful on systems that have EFI firmware. 1964 In addition, you should use the latest ELILO loader available 1965 at <http://elilo.sourceforge.net> in order to take advantage 1966 of EFI runtime services. However, even with this option, the 1967 resultant kernel should continue to boot on existing non-EFI 1968 platforms. 1969 1970config EFI_STUB 1971 bool "EFI stub support" 1972 depends on EFI 1973 select RELOCATABLE 1974 help 1975 This kernel feature allows a bzImage to be loaded directly 1976 by EFI firmware without the use of a bootloader. 1977 1978 See Documentation/admin-guide/efi-stub.rst for more information. 1979 1980config EFI_HANDOVER_PROTOCOL 1981 bool "EFI handover protocol (DEPRECATED)" 1982 depends on EFI_STUB 1983 default y 1984 help 1985 Select this in order to include support for the deprecated EFI 1986 handover protocol, which defines alternative entry points into the 1987 EFI stub. This is a practice that has no basis in the UEFI 1988 specification, and requires a priori knowledge on the part of the 1989 bootloader about Linux/x86 specific ways of passing the command line 1990 and initrd, and where in memory those assets may be loaded. 1991 1992 If in doubt, say Y. Even though the corresponding support is not 1993 present in upstream GRUB or other bootloaders, most distros build 1994 GRUB with numerous downstream patches applied, and may rely on the 1995 handover protocol as as result. 1996 1997config EFI_MIXED 1998 bool "EFI mixed-mode support" 1999 depends on EFI_STUB && X86_64 2000 help 2001 Enabling this feature allows a 64-bit kernel to be booted 2002 on a 32-bit firmware, provided that your CPU supports 64-bit 2003 mode. 2004 2005 Note that it is not possible to boot a mixed-mode enabled 2006 kernel via the EFI boot stub - a bootloader that supports 2007 the EFI handover protocol must be used. 2008 2009 If unsure, say N. 2010 2011config EFI_FAKE_MEMMAP 2012 bool "Enable EFI fake memory map" 2013 depends on EFI 2014 help 2015 Saying Y here will enable "efi_fake_mem" boot option. By specifying 2016 this parameter, you can add arbitrary attribute to specific memory 2017 range by updating original (firmware provided) EFI memmap. This is 2018 useful for debugging of EFI memmap related feature, e.g., Address 2019 Range Mirroring feature. 2020 2021config EFI_MAX_FAKE_MEM 2022 int "maximum allowable number of ranges in efi_fake_mem boot option" 2023 depends on EFI_FAKE_MEMMAP 2024 range 1 128 2025 default 8 2026 help 2027 Maximum allowable number of ranges in efi_fake_mem boot option. 2028 Ranges can be set up to this value using comma-separated list. 2029 The default value is 8. 2030 2031config EFI_RUNTIME_MAP 2032 bool "Export EFI runtime maps to sysfs" if EXPERT 2033 depends on EFI 2034 default KEXEC_CORE 2035 help 2036 Export EFI runtime memory regions to /sys/firmware/efi/runtime-map. 2037 That memory map is required by the 2nd kernel to set up EFI virtual 2038 mappings after kexec, but can also be used for debugging purposes. 2039 2040 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 2041 2042source "kernel/Kconfig.hz" 2043 2044config KEXEC 2045 bool "kexec system call" 2046 select KEXEC_CORE 2047 help 2048 kexec is a system call that implements the ability to shutdown your 2049 current kernel, and to start another kernel. It is like a reboot 2050 but it is independent of the system firmware. And like a reboot 2051 you can start any kernel with it, not just Linux. 2052 2053 The name comes from the similarity to the exec system call. 2054 2055 It is an ongoing process to be certain the hardware in a machine 2056 is properly shutdown, so do not be surprised if this code does not 2057 initially work for you. As of this writing the exact hardware 2058 interface is strongly in flux, so no good recommendation can be 2059 made. 2060 2061config KEXEC_FILE 2062 bool "kexec file based system call" 2063 select KEXEC_CORE 2064 select HAVE_IMA_KEXEC if IMA 2065 depends on X86_64 2066 depends on CRYPTO=y 2067 depends on CRYPTO_SHA256=y 2068 help 2069 This is new version of kexec system call. This system call is 2070 file based and takes file descriptors as system call argument 2071 for kernel and initramfs as opposed to list of segments as 2072 accepted by previous system call. 2073 2074config ARCH_HAS_KEXEC_PURGATORY 2075 def_bool KEXEC_FILE 2076 2077config KEXEC_SIG 2078 bool "Verify kernel signature during kexec_file_load() syscall" 2079 depends on KEXEC_FILE 2080 help 2081 2082 This option makes the kexec_file_load() syscall check for a valid 2083 signature of the kernel image. The image can still be loaded without 2084 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2085 there's a signature that we can check, then it must be valid. 2086 2087 In addition to this option, you need to enable signature 2088 verification for the corresponding kernel image type being 2089 loaded in order for this to work. 2090 2091config KEXEC_SIG_FORCE 2092 bool "Require a valid signature in kexec_file_load() syscall" 2093 depends on KEXEC_SIG 2094 help 2095 This option makes kernel signature verification mandatory for 2096 the kexec_file_load() syscall. 2097 2098config KEXEC_BZIMAGE_VERIFY_SIG 2099 bool "Enable bzImage signature verification support" 2100 depends on KEXEC_SIG 2101 depends on SIGNED_PE_FILE_VERIFICATION 2102 select SYSTEM_TRUSTED_KEYRING 2103 help 2104 Enable bzImage signature verification support. 2105 2106config CRASH_DUMP 2107 bool "kernel crash dumps" 2108 depends on X86_64 || (X86_32 && HIGHMEM) 2109 help 2110 Generate crash dump after being started by kexec. 2111 This should be normally only set in special crash dump kernels 2112 which are loaded in the main kernel with kexec-tools into 2113 a specially reserved region and then later executed after 2114 a crash by kdump/kexec. The crash dump kernel must be compiled 2115 to a memory address not used by the main kernel or BIOS using 2116 PHYSICAL_START, or it must be built as a relocatable image 2117 (CONFIG_RELOCATABLE=y). 2118 For more details see Documentation/admin-guide/kdump/kdump.rst 2119 2120config KEXEC_JUMP 2121 bool "kexec jump" 2122 depends on KEXEC && HIBERNATION 2123 help 2124 Jump between original kernel and kexeced kernel and invoke 2125 code in physical address mode via KEXEC 2126 2127config PHYSICAL_START 2128 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2129 default "0x1000000" 2130 help 2131 This gives the physical address where the kernel is loaded. 2132 2133 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2134 bzImage will decompress itself to above physical address and 2135 run from there. Otherwise, bzImage will run from the address where 2136 it has been loaded by the boot loader and will ignore above physical 2137 address. 2138 2139 In normal kdump cases one does not have to set/change this option 2140 as now bzImage can be compiled as a completely relocatable image 2141 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2142 address. This option is mainly useful for the folks who don't want 2143 to use a bzImage for capturing the crash dump and want to use a 2144 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2145 to be specifically compiled to run from a specific memory area 2146 (normally a reserved region) and this option comes handy. 2147 2148 So if you are using bzImage for capturing the crash dump, 2149 leave the value here unchanged to 0x1000000 and set 2150 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2151 for capturing the crash dump change this value to start of 2152 the reserved region. In other words, it can be set based on 2153 the "X" value as specified in the "crashkernel=YM@XM" 2154 command line boot parameter passed to the panic-ed 2155 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2156 for more details about crash dumps. 2157 2158 Usage of bzImage for capturing the crash dump is recommended as 2159 one does not have to build two kernels. Same kernel can be used 2160 as production kernel and capture kernel. Above option should have 2161 gone away after relocatable bzImage support is introduced. But it 2162 is present because there are users out there who continue to use 2163 vmlinux for dump capture. This option should go away down the 2164 line. 2165 2166 Don't change this unless you know what you are doing. 2167 2168config RELOCATABLE 2169 bool "Build a relocatable kernel" 2170 default y 2171 help 2172 This builds a kernel image that retains relocation information 2173 so it can be loaded someplace besides the default 1MB. 2174 The relocations tend to make the kernel binary about 10% larger, 2175 but are discarded at runtime. 2176 2177 One use is for the kexec on panic case where the recovery kernel 2178 must live at a different physical address than the primary 2179 kernel. 2180 2181 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2182 it has been loaded at and the compile time physical address 2183 (CONFIG_PHYSICAL_START) is used as the minimum location. 2184 2185config RANDOMIZE_BASE 2186 bool "Randomize the address of the kernel image (KASLR)" 2187 depends on RELOCATABLE 2188 default y 2189 help 2190 In support of Kernel Address Space Layout Randomization (KASLR), 2191 this randomizes the physical address at which the kernel image 2192 is decompressed and the virtual address where the kernel 2193 image is mapped, as a security feature that deters exploit 2194 attempts relying on knowledge of the location of kernel 2195 code internals. 2196 2197 On 64-bit, the kernel physical and virtual addresses are 2198 randomized separately. The physical address will be anywhere 2199 between 16MB and the top of physical memory (up to 64TB). The 2200 virtual address will be randomized from 16MB up to 1GB (9 bits 2201 of entropy). Note that this also reduces the memory space 2202 available to kernel modules from 1.5GB to 1GB. 2203 2204 On 32-bit, the kernel physical and virtual addresses are 2205 randomized together. They will be randomized from 16MB up to 2206 512MB (8 bits of entropy). 2207 2208 Entropy is generated using the RDRAND instruction if it is 2209 supported. If RDTSC is supported, its value is mixed into 2210 the entropy pool as well. If neither RDRAND nor RDTSC are 2211 supported, then entropy is read from the i8254 timer. The 2212 usable entropy is limited by the kernel being built using 2213 2GB addressing, and that PHYSICAL_ALIGN must be at a 2214 minimum of 2MB. As a result, only 10 bits of entropy are 2215 theoretically possible, but the implementations are further 2216 limited due to memory layouts. 2217 2218 If unsure, say Y. 2219 2220# Relocation on x86 needs some additional build support 2221config X86_NEED_RELOCS 2222 def_bool y 2223 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2224 2225config PHYSICAL_ALIGN 2226 hex "Alignment value to which kernel should be aligned" 2227 default "0x200000" 2228 range 0x2000 0x1000000 if X86_32 2229 range 0x200000 0x1000000 if X86_64 2230 help 2231 This value puts the alignment restrictions on physical address 2232 where kernel is loaded and run from. Kernel is compiled for an 2233 address which meets above alignment restriction. 2234 2235 If bootloader loads the kernel at a non-aligned address and 2236 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2237 address aligned to above value and run from there. 2238 2239 If bootloader loads the kernel at a non-aligned address and 2240 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2241 load address and decompress itself to the address it has been 2242 compiled for and run from there. The address for which kernel is 2243 compiled already meets above alignment restrictions. Hence the 2244 end result is that kernel runs from a physical address meeting 2245 above alignment restrictions. 2246 2247 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2248 this value must be a multiple of 0x200000. 2249 2250 Don't change this unless you know what you are doing. 2251 2252config DYNAMIC_MEMORY_LAYOUT 2253 bool 2254 help 2255 This option makes base addresses of vmalloc and vmemmap as well as 2256 __PAGE_OFFSET movable during boot. 2257 2258config RANDOMIZE_MEMORY 2259 bool "Randomize the kernel memory sections" 2260 depends on X86_64 2261 depends on RANDOMIZE_BASE 2262 select DYNAMIC_MEMORY_LAYOUT 2263 default RANDOMIZE_BASE 2264 help 2265 Randomizes the base virtual address of kernel memory sections 2266 (physical memory mapping, vmalloc & vmemmap). This security feature 2267 makes exploits relying on predictable memory locations less reliable. 2268 2269 The order of allocations remains unchanged. Entropy is generated in 2270 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2271 configuration have in average 30,000 different possible virtual 2272 addresses for each memory section. 2273 2274 If unsure, say Y. 2275 2276config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2277 hex "Physical memory mapping padding" if EXPERT 2278 depends on RANDOMIZE_MEMORY 2279 default "0xa" if MEMORY_HOTPLUG 2280 default "0x0" 2281 range 0x1 0x40 if MEMORY_HOTPLUG 2282 range 0x0 0x40 2283 help 2284 Define the padding in terabytes added to the existing physical 2285 memory size during kernel memory randomization. It is useful 2286 for memory hotplug support but reduces the entropy available for 2287 address randomization. 2288 2289 If unsure, leave at the default value. 2290 2291config ADDRESS_MASKING 2292 bool "Linear Address Masking support" 2293 depends on X86_64 2294 help 2295 Linear Address Masking (LAM) modifies the checking that is applied 2296 to 64-bit linear addresses, allowing software to use of the 2297 untranslated address bits for metadata. 2298 2299 The capability can be used for efficient address sanitizers (ASAN) 2300 implementation and for optimizations in JITs. 2301 2302config HOTPLUG_CPU 2303 def_bool y 2304 depends on SMP 2305 2306config COMPAT_VDSO 2307 def_bool n 2308 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2309 depends on COMPAT_32 2310 help 2311 Certain buggy versions of glibc will crash if they are 2312 presented with a 32-bit vDSO that is not mapped at the address 2313 indicated in its segment table. 2314 2315 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2316 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2317 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2318 the only released version with the bug, but OpenSUSE 9 2319 contains a buggy "glibc 2.3.2". 2320 2321 The symptom of the bug is that everything crashes on startup, saying: 2322 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2323 2324 Saying Y here changes the default value of the vdso32 boot 2325 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2326 This works around the glibc bug but hurts performance. 2327 2328 If unsure, say N: if you are compiling your own kernel, you 2329 are unlikely to be using a buggy version of glibc. 2330 2331choice 2332 prompt "vsyscall table for legacy applications" 2333 depends on X86_64 2334 default LEGACY_VSYSCALL_XONLY 2335 help 2336 Legacy user code that does not know how to find the vDSO expects 2337 to be able to issue three syscalls by calling fixed addresses in 2338 kernel space. Since this location is not randomized with ASLR, 2339 it can be used to assist security vulnerability exploitation. 2340 2341 This setting can be changed at boot time via the kernel command 2342 line parameter vsyscall=[emulate|xonly|none]. Emulate mode 2343 is deprecated and can only be enabled using the kernel command 2344 line. 2345 2346 On a system with recent enough glibc (2.14 or newer) and no 2347 static binaries, you can say None without a performance penalty 2348 to improve security. 2349 2350 If unsure, select "Emulate execution only". 2351 2352 config LEGACY_VSYSCALL_XONLY 2353 bool "Emulate execution only" 2354 help 2355 The kernel traps and emulates calls into the fixed vsyscall 2356 address mapping and does not allow reads. This 2357 configuration is recommended when userspace might use the 2358 legacy vsyscall area but support for legacy binary 2359 instrumentation of legacy code is not needed. It mitigates 2360 certain uses of the vsyscall area as an ASLR-bypassing 2361 buffer. 2362 2363 config LEGACY_VSYSCALL_NONE 2364 bool "None" 2365 help 2366 There will be no vsyscall mapping at all. This will 2367 eliminate any risk of ASLR bypass due to the vsyscall 2368 fixed address mapping. Attempts to use the vsyscalls 2369 will be reported to dmesg, so that either old or 2370 malicious userspace programs can be identified. 2371 2372endchoice 2373 2374config CMDLINE_BOOL 2375 bool "Built-in kernel command line" 2376 help 2377 Allow for specifying boot arguments to the kernel at 2378 build time. On some systems (e.g. embedded ones), it is 2379 necessary or convenient to provide some or all of the 2380 kernel boot arguments with the kernel itself (that is, 2381 to not rely on the boot loader to provide them.) 2382 2383 To compile command line arguments into the kernel, 2384 set this option to 'Y', then fill in the 2385 boot arguments in CONFIG_CMDLINE. 2386 2387 Systems with fully functional boot loaders (i.e. non-embedded) 2388 should leave this option set to 'N'. 2389 2390config CMDLINE 2391 string "Built-in kernel command string" 2392 depends on CMDLINE_BOOL 2393 default "" 2394 help 2395 Enter arguments here that should be compiled into the kernel 2396 image and used at boot time. If the boot loader provides a 2397 command line at boot time, it is appended to this string to 2398 form the full kernel command line, when the system boots. 2399 2400 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2401 change this behavior. 2402 2403 In most cases, the command line (whether built-in or provided 2404 by the boot loader) should specify the device for the root 2405 file system. 2406 2407config CMDLINE_OVERRIDE 2408 bool "Built-in command line overrides boot loader arguments" 2409 depends on CMDLINE_BOOL && CMDLINE != "" 2410 help 2411 Set this option to 'Y' to have the kernel ignore the boot loader 2412 command line, and use ONLY the built-in command line. 2413 2414 This is used to work around broken boot loaders. This should 2415 be set to 'N' under normal conditions. 2416 2417config MODIFY_LDT_SYSCALL 2418 bool "Enable the LDT (local descriptor table)" if EXPERT 2419 default y 2420 help 2421 Linux can allow user programs to install a per-process x86 2422 Local Descriptor Table (LDT) using the modify_ldt(2) system 2423 call. This is required to run 16-bit or segmented code such as 2424 DOSEMU or some Wine programs. It is also used by some very old 2425 threading libraries. 2426 2427 Enabling this feature adds a small amount of overhead to 2428 context switches and increases the low-level kernel attack 2429 surface. Disabling it removes the modify_ldt(2) system call. 2430 2431 Saying 'N' here may make sense for embedded or server kernels. 2432 2433config STRICT_SIGALTSTACK_SIZE 2434 bool "Enforce strict size checking for sigaltstack" 2435 depends on DYNAMIC_SIGFRAME 2436 help 2437 For historical reasons MINSIGSTKSZ is a constant which became 2438 already too small with AVX512 support. Add a mechanism to 2439 enforce strict checking of the sigaltstack size against the 2440 real size of the FPU frame. This option enables the check 2441 by default. It can also be controlled via the kernel command 2442 line option 'strict_sas_size' independent of this config 2443 switch. Enabling it might break existing applications which 2444 allocate a too small sigaltstack but 'work' because they 2445 never get a signal delivered. 2446 2447 Say 'N' unless you want to really enforce this check. 2448 2449source "kernel/livepatch/Kconfig" 2450 2451endmenu 2452 2453config CC_HAS_SLS 2454 def_bool $(cc-option,-mharden-sls=all) 2455 2456config CC_HAS_RETURN_THUNK 2457 def_bool $(cc-option,-mfunction-return=thunk-extern) 2458 2459config CC_HAS_ENTRY_PADDING 2460 def_bool $(cc-option,-fpatchable-function-entry=16,16) 2461 2462config FUNCTION_PADDING_CFI 2463 int 2464 default 59 if FUNCTION_ALIGNMENT_64B 2465 default 27 if FUNCTION_ALIGNMENT_32B 2466 default 11 if FUNCTION_ALIGNMENT_16B 2467 default 3 if FUNCTION_ALIGNMENT_8B 2468 default 0 2469 2470# Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG 2471# except Kconfig can't do arithmetic :/ 2472config FUNCTION_PADDING_BYTES 2473 int 2474 default FUNCTION_PADDING_CFI if CFI_CLANG 2475 default FUNCTION_ALIGNMENT 2476 2477config CALL_PADDING 2478 def_bool n 2479 depends on CC_HAS_ENTRY_PADDING && OBJTOOL 2480 select FUNCTION_ALIGNMENT_16B 2481 2482config FINEIBT 2483 def_bool y 2484 depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE 2485 select CALL_PADDING 2486 2487config HAVE_CALL_THUNKS 2488 def_bool y 2489 depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL 2490 2491config CALL_THUNKS 2492 def_bool n 2493 select CALL_PADDING 2494 2495config PREFIX_SYMBOLS 2496 def_bool y 2497 depends on CALL_PADDING && !CFI_CLANG 2498 2499menuconfig SPECULATION_MITIGATIONS 2500 bool "Mitigations for speculative execution vulnerabilities" 2501 default y 2502 help 2503 Say Y here to enable options which enable mitigations for 2504 speculative execution hardware vulnerabilities. 2505 2506 If you say N, all mitigations will be disabled. You really 2507 should know what you are doing to say so. 2508 2509if SPECULATION_MITIGATIONS 2510 2511config PAGE_TABLE_ISOLATION 2512 bool "Remove the kernel mapping in user mode" 2513 default y 2514 depends on (X86_64 || X86_PAE) 2515 help 2516 This feature reduces the number of hardware side channels by 2517 ensuring that the majority of kernel addresses are not mapped 2518 into userspace. 2519 2520 See Documentation/arch/x86/pti.rst for more details. 2521 2522config RETPOLINE 2523 bool "Avoid speculative indirect branches in kernel" 2524 select OBJTOOL if HAVE_OBJTOOL 2525 default y 2526 help 2527 Compile kernel with the retpoline compiler options to guard against 2528 kernel-to-user data leaks by avoiding speculative indirect 2529 branches. Requires a compiler with -mindirect-branch=thunk-extern 2530 support for full protection. The kernel may run slower. 2531 2532config RETHUNK 2533 bool "Enable return-thunks" 2534 depends on RETPOLINE && CC_HAS_RETURN_THUNK 2535 select OBJTOOL if HAVE_OBJTOOL 2536 default y if X86_64 2537 help 2538 Compile the kernel with the return-thunks compiler option to guard 2539 against kernel-to-user data leaks by avoiding return speculation. 2540 Requires a compiler with -mfunction-return=thunk-extern 2541 support for full protection. The kernel may run slower. 2542 2543config CPU_UNRET_ENTRY 2544 bool "Enable UNRET on kernel entry" 2545 depends on CPU_SUP_AMD && RETHUNK && X86_64 2546 default y 2547 help 2548 Compile the kernel with support for the retbleed=unret mitigation. 2549 2550config CALL_DEPTH_TRACKING 2551 bool "Mitigate RSB underflow with call depth tracking" 2552 depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS 2553 select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE 2554 select CALL_THUNKS 2555 default y 2556 help 2557 Compile the kernel with call depth tracking to mitigate the Intel 2558 SKL Return-Speculation-Buffer (RSB) underflow issue. The 2559 mitigation is off by default and needs to be enabled on the 2560 kernel command line via the retbleed=stuff option. For 2561 non-affected systems the overhead of this option is marginal as 2562 the call depth tracking is using run-time generated call thunks 2563 in a compiler generated padding area and call patching. This 2564 increases text size by ~5%. For non affected systems this space 2565 is unused. On affected SKL systems this results in a significant 2566 performance gain over the IBRS mitigation. 2567 2568config CALL_THUNKS_DEBUG 2569 bool "Enable call thunks and call depth tracking debugging" 2570 depends on CALL_DEPTH_TRACKING 2571 select FUNCTION_ALIGNMENT_32B 2572 default n 2573 help 2574 Enable call/ret counters for imbalance detection and build in 2575 a noisy dmesg about callthunks generation and call patching for 2576 trouble shooting. The debug prints need to be enabled on the 2577 kernel command line with 'debug-callthunks'. 2578 Only enable this when you are debugging call thunks as this 2579 creates a noticeable runtime overhead. If unsure say N. 2580 2581config CPU_IBPB_ENTRY 2582 bool "Enable IBPB on kernel entry" 2583 depends on CPU_SUP_AMD && X86_64 2584 default y 2585 help 2586 Compile the kernel with support for the retbleed=ibpb mitigation. 2587 2588config CPU_IBRS_ENTRY 2589 bool "Enable IBRS on kernel entry" 2590 depends on CPU_SUP_INTEL && X86_64 2591 default y 2592 help 2593 Compile the kernel with support for the spectre_v2=ibrs mitigation. 2594 This mitigates both spectre_v2 and retbleed at great cost to 2595 performance. 2596 2597config SLS 2598 bool "Mitigate Straight-Line-Speculation" 2599 depends on CC_HAS_SLS && X86_64 2600 select OBJTOOL if HAVE_OBJTOOL 2601 default n 2602 help 2603 Compile the kernel with straight-line-speculation options to guard 2604 against straight line speculation. The kernel image might be slightly 2605 larger. 2606 2607endif 2608 2609config ARCH_HAS_ADD_PAGES 2610 def_bool y 2611 depends on ARCH_ENABLE_MEMORY_HOTPLUG 2612 2613config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 2614 def_bool y 2615 2616menu "Power management and ACPI options" 2617 2618config ARCH_HIBERNATION_HEADER 2619 def_bool y 2620 depends on HIBERNATION 2621 2622source "kernel/power/Kconfig" 2623 2624source "drivers/acpi/Kconfig" 2625 2626config X86_APM_BOOT 2627 def_bool y 2628 depends on APM 2629 2630menuconfig APM 2631 tristate "APM (Advanced Power Management) BIOS support" 2632 depends on X86_32 && PM_SLEEP 2633 help 2634 APM is a BIOS specification for saving power using several different 2635 techniques. This is mostly useful for battery powered laptops with 2636 APM compliant BIOSes. If you say Y here, the system time will be 2637 reset after a RESUME operation, the /proc/apm device will provide 2638 battery status information, and user-space programs will receive 2639 notification of APM "events" (e.g. battery status change). 2640 2641 If you select "Y" here, you can disable actual use of the APM 2642 BIOS by passing the "apm=off" option to the kernel at boot time. 2643 2644 Note that the APM support is almost completely disabled for 2645 machines with more than one CPU. 2646 2647 In order to use APM, you will need supporting software. For location 2648 and more information, read <file:Documentation/power/apm-acpi.rst> 2649 and the Battery Powered Linux mini-HOWTO, available from 2650 <http://www.tldp.org/docs.html#howto>. 2651 2652 This driver does not spin down disk drives (see the hdparm(8) 2653 manpage ("man 8 hdparm") for that), and it doesn't turn off 2654 VESA-compliant "green" monitors. 2655 2656 This driver does not support the TI 4000M TravelMate and the ACER 2657 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2658 desktop machines also don't have compliant BIOSes, and this driver 2659 may cause those machines to panic during the boot phase. 2660 2661 Generally, if you don't have a battery in your machine, there isn't 2662 much point in using this driver and you should say N. If you get 2663 random kernel OOPSes or reboots that don't seem to be related to 2664 anything, try disabling/enabling this option (or disabling/enabling 2665 APM in your BIOS). 2666 2667 Some other things you should try when experiencing seemingly random, 2668 "weird" problems: 2669 2670 1) make sure that you have enough swap space and that it is 2671 enabled. 2672 2) pass the "idle=poll" option to the kernel 2673 3) switch on floating point emulation in the kernel and pass 2674 the "no387" option to the kernel 2675 4) pass the "floppy=nodma" option to the kernel 2676 5) pass the "mem=4M" option to the kernel (thereby disabling 2677 all but the first 4 MB of RAM) 2678 6) make sure that the CPU is not over clocked. 2679 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2680 8) disable the cache from your BIOS settings 2681 9) install a fan for the video card or exchange video RAM 2682 10) install a better fan for the CPU 2683 11) exchange RAM chips 2684 12) exchange the motherboard. 2685 2686 To compile this driver as a module, choose M here: the 2687 module will be called apm. 2688 2689if APM 2690 2691config APM_IGNORE_USER_SUSPEND 2692 bool "Ignore USER SUSPEND" 2693 help 2694 This option will ignore USER SUSPEND requests. On machines with a 2695 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2696 series notebooks, it is necessary to say Y because of a BIOS bug. 2697 2698config APM_DO_ENABLE 2699 bool "Enable PM at boot time" 2700 help 2701 Enable APM features at boot time. From page 36 of the APM BIOS 2702 specification: "When disabled, the APM BIOS does not automatically 2703 power manage devices, enter the Standby State, enter the Suspend 2704 State, or take power saving steps in response to CPU Idle calls." 2705 This driver will make CPU Idle calls when Linux is idle (unless this 2706 feature is turned off -- see "Do CPU IDLE calls", below). This 2707 should always save battery power, but more complicated APM features 2708 will be dependent on your BIOS implementation. You may need to turn 2709 this option off if your computer hangs at boot time when using APM 2710 support, or if it beeps continuously instead of suspending. Turn 2711 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2712 T400CDT. This is off by default since most machines do fine without 2713 this feature. 2714 2715config APM_CPU_IDLE 2716 depends on CPU_IDLE 2717 bool "Make CPU Idle calls when idle" 2718 help 2719 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2720 On some machines, this can activate improved power savings, such as 2721 a slowed CPU clock rate, when the machine is idle. These idle calls 2722 are made after the idle loop has run for some length of time (e.g., 2723 333 mS). On some machines, this will cause a hang at boot time or 2724 whenever the CPU becomes idle. (On machines with more than one CPU, 2725 this option does nothing.) 2726 2727config APM_DISPLAY_BLANK 2728 bool "Enable console blanking using APM" 2729 help 2730 Enable console blanking using the APM. Some laptops can use this to 2731 turn off the LCD backlight when the screen blanker of the Linux 2732 virtual console blanks the screen. Note that this is only used by 2733 the virtual console screen blanker, and won't turn off the backlight 2734 when using the X Window system. This also doesn't have anything to 2735 do with your VESA-compliant power-saving monitor. Further, this 2736 option doesn't work for all laptops -- it might not turn off your 2737 backlight at all, or it might print a lot of errors to the console, 2738 especially if you are using gpm. 2739 2740config APM_ALLOW_INTS 2741 bool "Allow interrupts during APM BIOS calls" 2742 help 2743 Normally we disable external interrupts while we are making calls to 2744 the APM BIOS as a measure to lessen the effects of a badly behaving 2745 BIOS implementation. The BIOS should reenable interrupts if it 2746 needs to. Unfortunately, some BIOSes do not -- especially those in 2747 many of the newer IBM Thinkpads. If you experience hangs when you 2748 suspend, try setting this to Y. Otherwise, say N. 2749 2750endif # APM 2751 2752source "drivers/cpufreq/Kconfig" 2753 2754source "drivers/cpuidle/Kconfig" 2755 2756source "drivers/idle/Kconfig" 2757 2758endmenu 2759 2760menu "Bus options (PCI etc.)" 2761 2762choice 2763 prompt "PCI access mode" 2764 depends on X86_32 && PCI 2765 default PCI_GOANY 2766 help 2767 On PCI systems, the BIOS can be used to detect the PCI devices and 2768 determine their configuration. However, some old PCI motherboards 2769 have BIOS bugs and may crash if this is done. Also, some embedded 2770 PCI-based systems don't have any BIOS at all. Linux can also try to 2771 detect the PCI hardware directly without using the BIOS. 2772 2773 With this option, you can specify how Linux should detect the 2774 PCI devices. If you choose "BIOS", the BIOS will be used, 2775 if you choose "Direct", the BIOS won't be used, and if you 2776 choose "MMConfig", then PCI Express MMCONFIG will be used. 2777 If you choose "Any", the kernel will try MMCONFIG, then the 2778 direct access method and falls back to the BIOS if that doesn't 2779 work. If unsure, go with the default, which is "Any". 2780 2781config PCI_GOBIOS 2782 bool "BIOS" 2783 2784config PCI_GOMMCONFIG 2785 bool "MMConfig" 2786 2787config PCI_GODIRECT 2788 bool "Direct" 2789 2790config PCI_GOOLPC 2791 bool "OLPC XO-1" 2792 depends on OLPC 2793 2794config PCI_GOANY 2795 bool "Any" 2796 2797endchoice 2798 2799config PCI_BIOS 2800 def_bool y 2801 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2802 2803# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2804config PCI_DIRECT 2805 def_bool y 2806 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2807 2808config PCI_MMCONFIG 2809 bool "Support mmconfig PCI config space access" if X86_64 2810 default y 2811 depends on PCI && (ACPI || JAILHOUSE_GUEST) 2812 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2813 2814config PCI_OLPC 2815 def_bool y 2816 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2817 2818config PCI_XEN 2819 def_bool y 2820 depends on PCI && XEN 2821 2822config MMCONF_FAM10H 2823 def_bool y 2824 depends on X86_64 && PCI_MMCONFIG && ACPI 2825 2826config PCI_CNB20LE_QUIRK 2827 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2828 depends on PCI 2829 help 2830 Read the PCI windows out of the CNB20LE host bridge. This allows 2831 PCI hotplug to work on systems with the CNB20LE chipset which do 2832 not have ACPI. 2833 2834 There's no public spec for this chipset, and this functionality 2835 is known to be incomplete. 2836 2837 You should say N unless you know you need this. 2838 2839config ISA_BUS 2840 bool "ISA bus support on modern systems" if EXPERT 2841 help 2842 Expose ISA bus device drivers and options available for selection and 2843 configuration. Enable this option if your target machine has an ISA 2844 bus. ISA is an older system, displaced by PCI and newer bus 2845 architectures -- if your target machine is modern, it probably does 2846 not have an ISA bus. 2847 2848 If unsure, say N. 2849 2850# x86_64 have no ISA slots, but can have ISA-style DMA. 2851config ISA_DMA_API 2852 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2853 default y 2854 help 2855 Enables ISA-style DMA support for devices requiring such controllers. 2856 If unsure, say Y. 2857 2858if X86_32 2859 2860config ISA 2861 bool "ISA support" 2862 help 2863 Find out whether you have ISA slots on your motherboard. ISA is the 2864 name of a bus system, i.e. the way the CPU talks to the other stuff 2865 inside your box. Other bus systems are PCI, EISA, MicroChannel 2866 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2867 newer boards don't support it. If you have ISA, say Y, otherwise N. 2868 2869config SCx200 2870 tristate "NatSemi SCx200 support" 2871 help 2872 This provides basic support for National Semiconductor's 2873 (now AMD's) Geode processors. The driver probes for the 2874 PCI-IDs of several on-chip devices, so its a good dependency 2875 for other scx200_* drivers. 2876 2877 If compiled as a module, the driver is named scx200. 2878 2879config SCx200HR_TIMER 2880 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2881 depends on SCx200 2882 default y 2883 help 2884 This driver provides a clocksource built upon the on-chip 2885 27MHz high-resolution timer. Its also a workaround for 2886 NSC Geode SC-1100's buggy TSC, which loses time when the 2887 processor goes idle (as is done by the scheduler). The 2888 other workaround is idle=poll boot option. 2889 2890config OLPC 2891 bool "One Laptop Per Child support" 2892 depends on !X86_PAE 2893 select GPIOLIB 2894 select OF 2895 select OF_PROMTREE 2896 select IRQ_DOMAIN 2897 select OLPC_EC 2898 help 2899 Add support for detecting the unique features of the OLPC 2900 XO hardware. 2901 2902config OLPC_XO1_PM 2903 bool "OLPC XO-1 Power Management" 2904 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2905 help 2906 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2907 2908config OLPC_XO1_RTC 2909 bool "OLPC XO-1 Real Time Clock" 2910 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2911 help 2912 Add support for the XO-1 real time clock, which can be used as a 2913 programmable wakeup source. 2914 2915config OLPC_XO1_SCI 2916 bool "OLPC XO-1 SCI extras" 2917 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2918 depends on INPUT=y 2919 select POWER_SUPPLY 2920 help 2921 Add support for SCI-based features of the OLPC XO-1 laptop: 2922 - EC-driven system wakeups 2923 - Power button 2924 - Ebook switch 2925 - Lid switch 2926 - AC adapter status updates 2927 - Battery status updates 2928 2929config OLPC_XO15_SCI 2930 bool "OLPC XO-1.5 SCI extras" 2931 depends on OLPC && ACPI 2932 select POWER_SUPPLY 2933 help 2934 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2935 - EC-driven system wakeups 2936 - AC adapter status updates 2937 - Battery status updates 2938 2939config ALIX 2940 bool "PCEngines ALIX System Support (LED setup)" 2941 select GPIOLIB 2942 help 2943 This option enables system support for the PCEngines ALIX. 2944 At present this just sets up LEDs for GPIO control on 2945 ALIX2/3/6 boards. However, other system specific setup should 2946 get added here. 2947 2948 Note: You must still enable the drivers for GPIO and LED support 2949 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2950 2951 Note: You have to set alix.force=1 for boards with Award BIOS. 2952 2953config NET5501 2954 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2955 select GPIOLIB 2956 help 2957 This option enables system support for the Soekris Engineering net5501. 2958 2959config GEOS 2960 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2961 select GPIOLIB 2962 depends on DMI 2963 help 2964 This option enables system support for the Traverse Technologies GEOS. 2965 2966config TS5500 2967 bool "Technologic Systems TS-5500 platform support" 2968 depends on MELAN 2969 select CHECK_SIGNATURE 2970 select NEW_LEDS 2971 select LEDS_CLASS 2972 help 2973 This option enables system support for the Technologic Systems TS-5500. 2974 2975endif # X86_32 2976 2977config AMD_NB 2978 def_bool y 2979 depends on CPU_SUP_AMD && PCI 2980 2981endmenu 2982 2983menu "Binary Emulations" 2984 2985config IA32_EMULATION 2986 bool "IA32 Emulation" 2987 depends on X86_64 2988 select ARCH_WANT_OLD_COMPAT_IPC 2989 select BINFMT_ELF 2990 select COMPAT_OLD_SIGACTION 2991 help 2992 Include code to run legacy 32-bit programs under a 2993 64-bit kernel. You should likely turn this on, unless you're 2994 100% sure that you don't have any 32-bit programs left. 2995 2996config X86_X32_ABI 2997 bool "x32 ABI for 64-bit mode" 2998 depends on X86_64 2999 # llvm-objcopy does not convert x86_64 .note.gnu.property or 3000 # compressed debug sections to x86_x32 properly: 3001 # https://github.com/ClangBuiltLinux/linux/issues/514 3002 # https://github.com/ClangBuiltLinux/linux/issues/1141 3003 depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm) 3004 help 3005 Include code to run binaries for the x32 native 32-bit ABI 3006 for 64-bit processors. An x32 process gets access to the 3007 full 64-bit register file and wide data path while leaving 3008 pointers at 32 bits for smaller memory footprint. 3009 3010config COMPAT_32 3011 def_bool y 3012 depends on IA32_EMULATION || X86_32 3013 select HAVE_UID16 3014 select OLD_SIGSUSPEND3 3015 3016config COMPAT 3017 def_bool y 3018 depends on IA32_EMULATION || X86_X32_ABI 3019 3020config COMPAT_FOR_U64_ALIGNMENT 3021 def_bool y 3022 depends on COMPAT 3023 3024endmenu 3025 3026config HAVE_ATOMIC_IOMAP 3027 def_bool y 3028 depends on X86_32 3029 3030source "arch/x86/kvm/Kconfig" 3031 3032source "arch/x86/Kconfig.assembler" 3033